Title of Invention	" A METHOD FOR PRODUCING SLEEVE-SHAPED INJECTION MOULDS AND AN INJECTION MOULDING MACHINE".
Abstract	The aim of the invention is to improve the cooling or subsequent cooling range during the production of pre—shaped bodies for PET bottles, so—called preforms. Water cooling is primarily used for initial cooling and also during subsequent coaling. The air action, however, is improved by assigning mechanically displaceable elements to the air side action. As a result, the security with regard to malfunctions during handling as well as the cooling action can be improved. When combined, two especially advantageous embodiments yield an optimal solution. A valve-like element is provided for ejecting and an air nozzle 40 is provided for the interiorof the reforms, said nozzle assisting in the handling and cooling.

Title of Invention

" A METHOD FOR PRODUCING SLEEVE-SHAPED INJECTION MOULDS AND AN INJECTION MOULDING MACHINE".

Abstract

The aim of the invention is to improve the cooling or subsequent cooling range during the production of pre—shaped bodies for PET bottles, so—called preforms. Water cooling is primarily used for initial cooling and also during subsequent coaling. The air action, however, is improved by assigning mechanically displaceable elements to the air side action. As a result, the security with regard to malfunctions during handling as well as the cooling action can be improved. When combined, two especially advantageous embodiments yield an optimal solution. A valve-like element is provided for ejecting and an air nozzle 40 is provided for the interiorof the reforms, said nozzle assisting in the handling and cooling.

Full Text	Technical scope A method producing a large number of a sleeve-shaped injection moulds closed on side with a floor, which are removed from the moulds after the injection sequence and after-cooled and thereby pushed into water cooling pipes, and again ejected and brought from their semi-solid condition on opening the mould halves into a shape-stable condition by means of water cooling and then handed over for further transportation; besides, also an injection moulding machine for production of sleeve-shaped injection moulds closed on one side with a floor, consisting of a lock-in and opening mechanism, removal and after-cooling units, in which at least corresponding to the number of injection moulds produced per cycle, water cooling pipes are provided for the injection moulds, whereby a pressure or underpressure chamber is arranged lying opposite to the push-in side for the injection moulds and connected to the cooling pipe takeover chamber for the injection moulds. State-of-the-art technology During production of the typical thick-walled injection moulds of the above mentioned type, for the attainable cycle time, the cooling time, especially the after-cooling time is an important and a decisive factor. The main cooling still takes place in the casting mould halves. Both the casting mould halves are intensively water-cooled during the casting process, so that the temperature in the mould can be reduced from approx. 280° upto approx. 70° to 80° C, at least in the edge layers. 2/3 of the cooling performance thereby takes place over the core, 1/3 by external cooling of the corresponding injection moulds. In the outer layers the so called glass temperature of approx. 140° C is very rapidly conducted. The actual casting sequence till removal of the injection moulds can be reduced to approx. 13 to 15 sec, with optimum quality with reference to the still semi-solid injection moulds. The injection moulds must be strengthened to such an extent that these can be gripped only with relatively large forces of ejection aids and can be passed on to a removal fixture without deformation or damages. The removal fixture has a mould adapted to the injection moulds, so that during subsequent treatment the shape of the injection moulds can be retained exactly. The more intensive water cooling in the casting mould halves takes place physically-conditioned and with respect to the enormous wall thickness, with a time lag, from outside to inside. This means that the temperature of 70° to 80° C is not achieved uniformly in the entire cross-section. The result is, that a rapid re-heating takes place from inside to outside, as. seen in the material cross-section, as soon as the intensive cooling effect is interrupted. The so-called after-cooling is very important due to two reasons. Firstly, any alteration in shape till the shape-stable condition, as well as surface damages, like pressure points etc. will have to be avoided. Secondly, it must be prevented that the cooling at higher temperature ranges takes place too slowly and that harmful crystal formation sets in locally due to re-heating. The objective is to have a uniformly amorphous condition, in the material of the cast mould. The surface of the injection moulds should no longer be sticky, as otherwise adhesive damages could occur in the relatively large boxes or packings where thousands of loose parts are poured in. Even in case of slight re-heating, the injection moulds should not exceed a surface temperature of 40° C. Practice shows that the after-cooling after removal of the castings from the injection cast mould is precisely as important as the main cooling in the casting moulds. The expert caster knows that even minor errors could have huge effects. While testing new materials, especially during production interruption due to process errors, there could be situations that the hot injection moulds remains somewhat too long on the mandrel-like positive moulds. The result could be, that due to the continuing shrinkage process in the injection moulds caused by the cooling, it may not be possible to get this out any more with the normal ejectior forces of the machine and can be released from the moulds only with special auxiliary devices. According to a first technique as per the state-of-the-art technology EP-PS 0 266 804, water is also used as cooling agent for after-cooling. The injection mould removed in semi-solid condition from the injection casting mould is cooled in water-cooled transportation and after-cooling units to such an extent, till a stable final condition is reached. The still semi-solid injection moulds are pushed into cooling cones surrounded by cooling water immediately after removal from the mould halves. In the last phase of the push-in sequence, the injection mould is totally pulled into the cooling cones with the help of underpressure and cooled there from outside. Application of the underpressure takes place through an air chamber or pressure chamber with which the inner space of the cooling sleeve opened on both sides is 4 directly connected. The inner contour of the cooling pipes is also relatively strongly conically shaped just like the outer contour of the sleeve-shaped injection mould. In this way the injection mould is at least theoretically constantly drawn during the cooling phase and the connected fading due to application of underpressure. In this way, an attempt is made to ensure that the injection mould remains in optimum cooling contact in the conical inner wall of the cooling cones. In practice, the projected ideal cooling contact is not always attainable. In a known solution, the injection moulds are after-cooled in lying position. In this case even small sticky points hinder the desired continuous drawing. After completing the concerned cooling phase or after achieving a shape-stable condition of the sleeve-shaped injection mould, the underpressure is switched off in the air chamber and overpressure is generated. All injection moulds are thereafter pushed out of the conical cooling sleeve like a piston by switching over to air overpressure. A second technique, the so-called air cooling, is described in the document US-PS 4 592 719. There it is suggested that the production rate of the preforms be increased, in that instead of the separated after-cooling station, atmospheric air be used for cooling. The air is used as cooling air during transportation or "handling" by means of directed flow inside as well as outside on the preforms with maximum cooling effect. A removal unit, which has as many suction pipes as moulded parts produced in an injection cycle, drives in between both the open mould halves. The suction pipes are then pushed via the preforms. At the same time air begins to flow through a suction line in the region of entire circumferential area of the injection moulds surrounded by the suction pipes, so that from the moment of being taken over into the suction sleeve these are cooled by air from outside. The removal unit goes out of the movement space of the mould halves after complete takeover of all injection moulds of a casting cycle. The mould halves are then immediately free again for the subsequent casting cycle. The removal unit swivels the preforms after the driving out movement from a horizontal to a vertical position. Simultaneously a transfer unit runs in exactly to a handover position above the removal unit. The transfer unit has the same number of inner grippers as suction pipes of the removal units. Timely, after handover of all injection moulds, and before opening of the mould halves again, the removal unit is swung back into the drive-in position, so that the next charge of injection moulds can be removed from the moulds. The transfer unit hands over in the mean time the new, shape-stable injection moulds to a transporter and goes back without the preforms again into the takeover position for the next charge. -5- The main disadvantage of the solution as per the document US-PS 4 592 719 is that the after-cooling time is so to speak unchangeably equal to the casting cycle time. Even if by means of suitable introduction of air one thus manages to reach even small increases of local air velocities and thus a certain reduction in time, the unchangeable physicality of the air cooling process is absolutely decisive for the production rate. An increase would only be possible by increasing the injection moulds produced per casting cycle in a multiple casting mould. This number is however restricted as a rule by the maximum press pressure of the injection moulding machine. The suggested technical method of cooling the preforms by air from inside as well as outside during removal and transportation, gives a system-caused restriction of the maximunTpossirJle quantities. The after-cooling time here restricts the performance capacity of the plant. The document EP-PS 0 718,084 has three different devices: a removal device and a transfer device as well as an after-cooling device. The transfer gripper has a double function, as the pet-forms are brought into the after-cooling unit as well as again removed from it. It is suggested to do away with a cooling in the transfer device, in order to be able to carry out quicker movement on account of corresponding weight saving. Advantageous however is the simultaneous doing away with a direct cooling on the inner side of the pet-forms. The subsequently published document EP 0 947 304 suggests a central cooling, an inner cooling with air by a combined device. The combination in a device includes the function of a transfer device, as well as an actual after-cooling from inside, till crystallisation is completely prevented in the inner side. A main cooling with the help of air is however less efficient than a cooling with a fluid medium. The above mentioned water cooling method is however also subjected to certain restrictions. In practice it is however seen, that with water cooling for the same cavity number by reducing the cycle time, much larger number of injection moulds can be produced, assuming of course that ideal conditions can be maintained. The cavities of the injection casting moulds could have irregularities, which leads to differences in the outer contour of the sleeve-shaped injection moulds. In the same way, not all inner contours of the cooling sleeves are exactly same. This leads to the fact that some of the sleeve-shaped injection moulds after completion of the cooling phase, already slide out of the cooling sleeve due to self-weight, but other sleeve-shaped injection moulds remain in the cooling pipes or even get stuck there. In such a -6- situation the blow pressure in the pressure chamber reduces due to the already emptied cooling pipes to the surrounding pressure level and is then no longer sufficient to push out the injection moulds remaining in some of the cooling pipes. This leads to an interruption upto the subsequent production cycle. Because the sleeve-shaped injection moulds remaining in some of the cooling pipes block the takeover of new injection moulds, these will have to be removed manually. Summaryof the invention It is the task of the invention to improve upon an injection moulding machine or corresponding method for production of sleeve-shaped injection moulds in such a way, that while guaranteeing an optimum cooling effect, the productivity can be increased, and especially an interruption of the production cycle, e.g. due to stuck injection moulds can be almost ruled out. The method as per the invention has the feature. that,the injection moulds are removed by a removing device from the open moulds and handed over to an after-cool ing unit by a transfer gripper, and in the shape-stable condition handed over by the after-cooling unit for further transportation, whereby the handover of the injection moulds takes place through air nozzles for an inner cooling of the injection moulds, which are arranged on the transfer gripper. The device as per the invention has the feature, that it has a transfer gripper with air nozzles for an inner cooling of the injection moulds corresponding in number to the injection moulds to be cooled, through which the injection moulds can be handed over by the removal device into the after-cooling unit. It has been recognised by the inventors that in the described state-of-the-art technology, the restriction of maximum possible production is somewhat self-imposed due to the "purity of the applied method". A totally mixed system is naturally not possible, as on one side simultaneously only one cooling-medium, air or water can be used. If however both mediums are specifically used with their own advantages, then only one can reach the optimum condition. The new solution is based on the very efficient water cooling, however also centrally uses the air forces by using mechanically adjustable elements improving the air-side — 7 — enect. Thus at the same time two new part-solution possibilities emerge, namely the effect at the level of air pressure as well as the level of air flow as cooling support. The investigations on,the basis of new invention have brought new findings to light. On the basis of the casting process it must follow, that the inner cooling with water is twice as sufficient as compared with outer cooling water. This statement however holds good only for the casting phase. For the after-cooling phase, due to a large number of reasons, preference is given to outer cooling with water. A very important reason is the parallel process of cooling and shrinking. If the more intensive cooling takes place from outside, then the preforms get released from the cooling sleeves lying outside. The opposite case would be very disadvantageous in this connection, as then one has the danger that the individual sleeve-shaped injection moulds could get stuck to the cooling mandrels. The shrinking process has the disadvantages in the first case, that the casting mould gets released more and more from the walling and direct cooling contact gets diminished and hence the cooling effect could become worse. This disadvantage comes to the fore, if the casting moulds get stuck in one and the same cooling pipe during the entire phase of after-cooling. As will be shown later, the new invention allows here also an improvement by "re-inserting'1 the casting moulds twice or several times in a correspondingly conceived after-cooling unit. Another problem area was identified regarding the thick walls, mainly however in the region of the base of the injection mould sleeves. In the solutions of the state-of-the-art technology of water cooling, this zone is significantly difficult to attain. Here, ways and means were looked for, in order to improve this particularly critical point. In respect to the task, namely increase in productivity with maximum possible product quality, at the same time a decoupling of the hitherto strong bond of casting cycle and after-cooling was endeavoured. The new invention now allows a large number of particularly advantageous design forms with respect to the task in question or the problems encountered. Lying opposite to the push-in end of the water cooling pipes, as in the state-of-the-art technology, a controllable pressure or underpressure chamber is foreseen. According to the new solution however, the pressure chamber is lockable with respect to the inner chamber of the cooling pipes, and is designed with adjustable elements, e.g. designed as valve elements or piston elements. Due to the valve effect, the injection moulds are suctioned in case of underpressure and held safe. In case of overpressure in the pressure chamber, the ejection of injection moulds is supported. 8 In the state-of-the-art technology, the injection mould forms along with the entire cross-section surface at the same time the locking piston of a valve. In the suction phase, simultaneously, e.g. 96 injection moulds are suctioned. Because each injection mould in itself forms a plug with the locked base and the larger diameter of the open threaded side with respect to the water cooling pipes, further suction air is stopped. The underpressure generated on the opposite side is retained till reversing. If now instead of underpressure an overpressure is generated, then simultaneously all 96 injection moulds are ejected due to air pressure effect. If the simultaneity of ejection is not possible, because one part flies out of the cooling sleeve faster, then in the state-of-the-art technology the air pressure collapses. Each time there is the danger, that for the particular preforms which can only be driven out with difficulty, the remaining air pressure will no longer be sufficient. According to the new solution, an additional auxiliary valve with significantly smaller, free flow cross-section is allocated to each injection mould. If for example, only half of the pieces are immediately ejected, then in this way the air pressure can be retained for the remaining ones or even increased. The auxiliary valve locks the passage in the water cooling pipe in an air-tight manner after the concerned injection mould has been ejected. According to a further, particularly advantageous design form, to the water cooling pipe on the side of the pressure or underpressure chamber a crowning base part is allocated in such a way, that for the purpose of intensifying the water cooling effect the injection mould with its hemispherical floor is immersed in the crowning floor part of the water cooling pipe or is sucked into the bulge due to the underpressure. Ideally, a bulging floor part is connected to each of the water cooling pipes without any clearance, or it could even be part of the water cooling pipes. In a small average passage opening, an adjustable valve pin is arranged. Experiments have shown that in case of the cone solution, two very important aspects have been overlooked so far. Firstly, a particularly critical part is the entire region of the injection mould floor. The desired continuous drawing presupposes that the injection mould is not on the floor right from the beginning. The consequence is that the floor of the injection mould is either not cooled at all or only insufficiently. The second aspect is, that at a temperature of 70 to 80° C the radiation part is still relatively high. Even if a slight clearance sets in on the outside after a few seconds due to shrinkage, this is not very serious at the beginning of the after-cooling. The cooling gain due to the contact surface in the floor region weighs more -9- than the slight loss on the circumferential surface. In addition to that, now the conicalness of the injection mould can remain restricted to the purely casting-technical requirement. According to a second very advantageous design form, for the region of the open push-in end of the water cooling pipes, the adjustable elements are designed as air nozzles, which are cyclicly pushed in into the injection moulds, and bring handling air into the inner side of the injection mould and/or can suction them off. In this way it has been possible to bring the cooling effect, particularly in combination with the above described outer flow cooling to a maximum effect, even in the zone, which according to the state-of-the-art technology was the bottleneck for cooling. This is above all applicable, if the inner cooling air is blown into the proximity of the floor. The entire range of after-cooling should preferably be designed in three stages, and has a removal device, a transfer gripper as well as an after-cooling unit. The air nozzle should preferably be part of the transfer gripper and as are designed as centring mandrel to hand over theinjectio'fi moulds from the removal unit to the after-cooling unit. A control is foreseen, which coordinates pulse-wise the transport steps and cyclically the cooling phases. The movement cycles or process intervention of the removal unit, the transfer gripper as well as the after-cooling unit can be adjusted independently for optimisation of the process or for production of a new product or for new product quality. The transfer unit takes over with the help of the air nozzles or centring mandrels the injection moulds from the removing gripper in a horizontal position With-a swinging-movement, the injection moulds are brought to a vertical position and pushed into the water-cooled sleeves of the after-cooling unit. During handover of the injection moulds from the removing gripper, ..the air nozzles preferably remain in a pushed-in position for several seconds. In this way, one gets the intensive blow cooling of particularly the semi-circular floor of the inner side of the injection mould. In this phase, the injection mould gets cooled from inside and from outside, i.e. double-side. With the new solution, the air effect is utilized in the best possible way in different ways, whether it is as cooling agent or by means of forces of pressure or underpressure. In this way, the so-called handling as well as the solidification phase gets significantly improved. The pressure conditions and the flow conditions are independently controlled on both sides with reference to the injection mould floors. In a coordinated manner, a blow-air flow and/or an underpressure condition is generated, so that accordingly the injection moulds can be retained -10- by underpressure on one or the other side, or through a pressure impact can be moved in one or the other direction. The air nozzles are preferably designed as suck-and-blow mandrels, with suction openings for the region of the open end of the injection moulds. Various operation conditions can be adjusted, e.g. a dominant air blow radiation in the region of the closed floor end in the inner part of the injection moulds, or a strong vacuum effect within the injection mould or a mixed form between both. This is particularly advantageous because the totally different phases can go into one another without time loss and partly also optimally overlap one another. This means that in the after-cooling phase the subsequent step can already begin, before the previous one has been totally completed. The transfer gripper and the removal unit are conceived for taking up of equal number of injection moulds, like the injection tool. On the other hand, the after-cooling unit has water cooling pipes preferably arranged parallel in two or multiple rows, or if required even arranged staggered. By corresponding cross-shifting and longitudinal shifting, the after-cooling unit can take up two or several charges of injection moulds for each injection moulding cycle for reducing the moulding cycle time and increasing the after-cooling time. By means of the measures described, the new solution allows a significant increase in efficiency. The phase of removal of the injection moulds from the mould halves and the complete hand over to the after-cooling unit approximately conforms to the time duration of a moulding cycle reduced to a minimum. The total after-cooling time can however be taken to twice or thrice the moulding cycle time. The new solution thereby allows specifically in certain phases a double cooling from inside and outside on the injection moulds, that too during a significant portion of the moulding cycle time immediately after removal the injection moulds from the mould halves. For large number of very advantageous rurtner design forms of the device, will be discloused in the following pages. The invention further pertains to the application of the method for the area of injection mould removal and/or for the area of after-cooling, whereby at least the ejection of the injection moulds by air pressure.through an adjustable valve element can take place supported from the air side, and the water cooling effect at the end of the injection mould removal as well as at the beginning of the after-cooling is supplemented by the air blow nozzles which can be mechanically adjusted in the interior of the injection mould. The invention further pertains to application of adjustable valve pins for supporting the ejection effect of compressed air and/or blow-mandrels, which can be adjusted in the inner -11- side of the injection moulds, for supporting the cooling effect primarily on the floor regions of the injection moulds for use in the removal device as well as the after-cooling unit, in case of injection moulding machines. Short description of the invention The invention is explained below with a few design example, as well as accompanying schematic drawings. The following are shown: Fig. 1 Schematically, a complete injection moulding machine with removal-, transfer- and after-cooling units for the injection moulds; Fig.2a and 2b Two different handling or handover situations for preforms; Fig.3 A known solution as per the state-of-the-art technology for water cooling of preforms; Fig.4 An example of a solution according to the new invention; Fig. 5a, 5b and 5c A particularly interesting design form of the solution with respect to outer cooling and drawing in or ejection of the injection moulds; Fig.6a to 6f Different parts and dispositions for the inner cooling by means of air nozzles or centering mandrels; Fig. 7a to 7d Different handling situations between removal gripper and transfer gripper; Fig. 8a to 8d Different handling situations between transfer gripper and after-cooling unit; Fig.9a and 9b A section or cutout of the after-cooling unit; Fig. 10 Schematically, the different cycles during production of preforms. -12- Ways and execution of the invention Figures 1 as well as 2a and 2b show an entire injection moulding machine for preforms with a machine bed 1, on which a fixed mould clamping plate 2 and an injection unit 3 are supported. A support plate 4 and a movable mould clamping plate 5 are axially shifable on the machine bed 1. The fixed mould clamping plate 5 and the support plate 4 are connected to one another by means of four booms 6, which go through the movable mould clamping plate 5 and guide it. Between the support plate 4 and the movable mould clamping plate 5 there is a drive unit 7 for generating the locking pressure. The fixed mould clamping plate 2 and the movable mould clamping plate 5 each carry a mould half 8 and 9, in which respectively a large number of part-moulds 8' and 9' and arranged, which together form cavities for generating a corresponding number of sleeve-shaped injection moulds. The part-moulds 8' are designed as mandrels, on which after opening of the mould halves 8 and 9 the sleeve-shaped injection moulds 10 adhere to. The injection moulds are at this point still in a semi-solid condition and are indicated by interrupted lines. The same injection moulds 10 in completely cooled condition are shown in fig. 1 in left top, where they are being ejected out of an after-cooling unit 19. The upper booms 6, for the purpose of better depiction of the details between the open mould halves, are shown interrupted. In the figures 2a and 2b, the four most important handling phases for injection moulds after completion of the moulding process are shown: "A" is the removal of the injection mould of preforms 10 from both the mould halves. The still semi-solid sleeve-shaped parts are thereby taken up by a removal unit 11 in the space between the open mould halves and sunk into the position "A", and with the help of this lifted to the position "B" (takeover device 11' in fig. 1). "B" is the handover position of the removal unit 11 with the preforms 10 on to a transfer gripper 12 ("B" in fig. 1). "C" is the handover of the preforms 10 from the transfer gripper 12 on to a after-cooling unit 19. "D" is the ejection of the cooled preforms brought to a shape-stable condition, from the after-cooling unit 19. Fig. 1 shows so-called snap shots of the four main steps for handling. In position "B" the sleeve-shaped injection moulds 10 arranged lying vertically above one another, are taken over -13- by the transfer gripper 12 or 12' and by swivelling the transfer unit in the direction of the arrow P brought to a position standing horizontally beside one another, according to the phase "C" .The transfer gripper 12 consists of a holding arm 14 swivellable around an axis 13, which carries a holder plate 15, to which a carrier plate 16 for the centering mandrel 8" is arranged in parallel distance. The carrier plate 16 can be adjusted parallel to the holder plate 15 by means of two hydraulic units 17 and 18, so that in the position "B" the sleeve-shaped injection moulds 10 can be brought out of the removing unit 11 and pushed into the after-cooling unit 19~lying above in the swivelled position "C". The respective handover takes place by increasing the distance between the holder plate 15 and the carrier plate 16. The still semi-solid sleeve-shaped injection moulds 10 are completely cooled in the after-cooling unit 19 and subsequently after shifting the after-cooling unit 19 in the position "D" can be ejected and thrown on to a conveyor belt 20. In figures 2a and 2b two situations with the respective cooling intervention mediums are similarly schematically depicted. In fig. 2a both the mould halves 8 and 9 are in closed condition, i.e. shown in the actual moulding phase, with connecting hoses for the cooling agents. Thereby "water'7 denotes water cooling and "air" the air impact. The maximum temperature reduction from 280° C to 80° C for the injection moulds 10 takes place within the closed moulds 8 and 9, for which an enormous amount of cooling water passage has to be ensured. The removal device 11 is in fig. 2a already in waiting position, which indicates the end of the injection phase. The reference sign 30 is the water cooling with corresponding inlet and outlet pipes, which for the case of simplicity have been indicated with arrows and are presumed to be known. The reference signs 31/32 denote the air sides, 31 stands for bfowing-in or compressed air feeding and 32 stands for vacuum or air suction. With that, one can already recognize at the principle level the application possibilities of air and water. In the injection casting moulds 8 and 9, during the injection moulding process, a pure water cooling takes place. In the removal device 11, air as well as water is used. In the transfer gripper or removal gripper 12 there is only an air effect. On the other hand, in the after-cooling device 19, again air and water are used. Fig. 2b shows the beginning of the removal of the preforms 10 from the open mould halves. Not shown are the auxiliary agents for pushing off the semi-solid preforms from the part-moulds 8'. A further important point is the handling in the region of after-cooling device. The after-cooling device can be horizontally driven in the direction of the arrow L independently during the removal phase "A", from a taking up position (shown in fig. 2b with drawn out lines) into an ejection position (shown -14- dashed). This working step is indicated in fig. 2 "C/D". As explained with the figures 9a and 9b, the after-cooling device 19 could have several times the holding capacity as compared to the number of cavities in the injection.casting mould halves. Ejection of the completely cooled preforms 10 can take place only after two, three or more injection moulding cycles, so that the after-cooling time would have to be correspondingly extended. For handing over the preforms from the transfer gripper 12 to the after-cooling device 19, the latter can additionally be set in the suitable position as indicated by arrow a, i.e. transversely shifted. Fig. 3 shows a cutout of a cooling device as per the state-of-the-art technology with a cooling block 21, in which several cooling sleeves 22 (filled black) are arranged. The cooling block 21 and the cooling sleeves 22 enclose a holow space 23, through which cooling water (marked dashed) flows. The inner space 24 of the cooling sleeves 22 serves the purpose of taking up sleeve-shaped injection moulds 10 and is conically tapered upward. At the lower end of the cooling sleeve there is an inlet and outlet opening 25, through which the still semi-solid injection moulds are introduced and from which the completely cooled injection moulds 10 are pushed out. At the upper end of the cooling sleeve 22 there is an opening 26 to an air chamber 27, which is surrounded by a cover 28. The sleeve-shaped injection moulds 10 represent so-called preforms for production of PET-jars, whereby in the left cooling sleeve a preform of size ??PF 30 x 165 and in the central cooling sleeve a shorter preform of size PF (j) 30 x 120 is arranged. The still semi-solid injection moulds are completely drawn in after pushing into the cooling sleeves on account of an underpressure existing with air chamber 27, so that injection mould comes in close cooling contact with the inner surface of the cooling sleeve 22. After completion of the cooling sequence, the now solid and shape-stable injection moulds are pushed out by means of applying overpressure from the air chamber 27. In this cooling device as per the state-of-the-art technology, as shown in fig. 3, there is the problem, that on account of irregularities in the production of mould cavities for the injection mould and the inner contour of the cooling sleeves, one or several injection moulds get blocked or could fall out of the cooling sleeve already towards the end of the cooling phase due to their self-weight. This is particularly applicable for the solution in which a cooling device as shown in fig. 3, is brought into a horizontal position for ejection. If in the air chamber one switches from underpressure to overpressure, in order to push out the completely cooled injection mould, on account of the large flow cross-sections due to prematurely released cooling sleeves 22' there could be insufficient pressure for pushing out the remaining -15- injection moulds. The production cycle is interrupted by not-emptied cooling sleeves, till all sleeves are manually released if required. Figures 4, 5a and 5b show design forms, in which as per the invention a simultaneous ejection of all injection moulds 10 at the end of the cooling phase is ensured. The design form as shown in fig. 4 shows a cooling sleeve 100, which has a tube-shaped connecting piece 101 at its upper end, which goes into the air chamber 27. The inner diameter 101' of the connecting piece 101 is greater than the inner space 102 of the cooling sleeve 100. In the connecting piece 101 there is a mechanically shiftable element in the form of a piston 103, whose outer diameter is lesser by a sufficient margin than the inner diameter 101' of the connecting piece 101, so that a defined air clearance is given. This air clearance forms a throttled passage channel 104 between the inner space of the cooling sleeve 100 and the air chamber 27. The transition from the larger inner space of the connecting piece 101 to the smaller space of the cooling sleeve 100 is designed in the shape of a valve seat ring 105, for which the piston 103 has a fitting valve seat ring 106. In the cooling phase, the injection mould 10 with its hemispherical floor 10' drawn into the cooling sleeve 100 lands above the valve seat ring 105 into the connecting piece 101. On application of underpressure of the air chamber 27 the underpressure branches over the passage channel 104 into the inner space of the cooling sleeve 100 and effects a drawing-in of the injection mould 10 into the cooling sleeve 100. After completion of the cooling phase, in the air chamber 27 one switches from underpressure to overpressure. The injection mould is ejected by the air pressure out of the cooling sleeve, whereby the piston element 103 moves downward. On impact of the piston 103 against the valve seat ring 105, on the one hand, the movement of the piston 103 is restricted, on the other hand, any kind of air exit from the air chamber 27 through the corresponding cooling sleeve is stopped. Before the subsequent filling of the cooling sleeve 100 with new, still semi-solid injection moulds 10, the piston 103 is again lifted up by the underpressure of the air chamber 27, whereby simultaneously the ring-shaped passage channel between piston 103 and inner walling of the connecting piece 101 is again opened, so that the underpressure in the inner space of the cooling sleeve 100 continues to branch out and the complete drawing-in of the injection moulds 10 can be effected. The design forms as shown in 5a and 5b show a preferred design with a cooling sleeve 200, which has a connecting piece 201 at its upper end, which is provided with a locking body 203 having a guide opening 202. This is provided in the lower region in a crowning 207, into which the injection mould 10 with its hemispherical flow gets immersed. In the guide opening 202 a thin piston element in the form of a valve pin -16- 204 is guided in a mechanically shiftable manner in an axial direction, whereby in the cylindrical passage opening 202 a passage channel 202' is designed in the form of grooves. The grooves (on the right side of fig. 5b) represent through-passages for an air exchange between the air chamber 27 and inner space of the cooling sleeve 200 within the crowning 207, and ensure a pressure exchange (as overpressure or underpressure) between the chamber 27 and the inner side of the cooling sleeve 200 (within the crowning 207). On the side towards the air chamber 27 of the through-opening 202, there is a truncated cone-shaped extension 205 into which the valve pin 204 with a correspondingly designed cone-shaped valve seat 206 can come to rest in a sealing manner (left side in fig. 5b with drawn-out lines). For filling the cooling sleeves 200 with the still semi-solid injection mould 10, by means of the underpressure of the air chamber 27 the valve pin 204 is drawn upward (fig. 5b right side). The underpressure branches off from the air chamber 27 through the grooves 202' in the passage opening 202 to the inner space of the cooling sleeve 200 and effects the complete drawing-in of the injection mould 10 (fig. 5a left side). After completion of the cooling phase, one switches from underpressure to overpressure in the air chamber 27. The valve pin 204 follows mechanically the completely cooled injection mould for short paths. The displacement path of the valve pin 204 is limited by the impact of its cone-shaped valve seat 206 on the truncated cone-shaped extension 205 of the passage opening 202 and a further passage of compressed air from the air chamber 27 to the inner space of the cooling sleeve is blocked. A residual pressure air cushion between the inner crowning 207, the cooling sleeve 200 as well as the outer hemispherical floor 10' effects as a result a complete ejection of the injection moulds 10 with corresponding air pressure. With the design forms according to the new solution it is ensured that in case of overpressure of the air chamber 27, the overpressure in the air chamber 27 remains constantly retained at the required magnitude, or can even be increased and all injection moulds 10 can be subjected to a maximum ejection force after completion of the cooling sequence. In fig. 6c an air nozzle 40 is shown. The air nozzle 40 is denoted below, depending on its respective function, as blowing mandrel or centering mandrel. The air nozzle 40 has a worm 41 on the left side, with which the air nozzles 40 are screwed on to the carrier plate 16. As shown in fig. 1, the carrier plate 16 has a large number of air nozzles 40, which are respectively arranged in several rows. In the carrier plate 16, as shown in fig. 6a, there are two air channel systems 42 and 43, whereby the air system 42 is designed for underpressure or vacuum (fig. 6d), and the air system 43 is designed for compressed air (fig. 6e), with -17- corresponding, not-shown connections for a compressed air generator or a suction blower or a vacuum pump. So that both air systems can be clearly separated, there are special bolts 43, 44 and 45 with necessary recesses on the adapters for mounting as well as penetration of the respective connecting pieces. The special bolts 43, 44 and 45 must compulsorily be screwed in or out in the correct sequence. In the completely mounted condition, both the air systems must be sealed against one another and should be able to fulfil their own functions. For the compressed air side a blower tube 47 corresponding to the length "1" must be pushed-in in the right mounting sequence, and guides the blown air through a hole 48 in the air nozzle 40 upto the blowing opening 47, from where a blowing air beam 50 blows out. For fixed screwing of the worm 41, a hexagonal wrench 51 is connected to the air nozzle 40, and a sealing ring 52 on the opposite side. The suction air connection 53 goes through a ring channel 54 as well as several cross-holes 55, which close to the sealing ring 52 connect the ring channel 54 on the outer side. From this we obtain, that air can be blown out through the blowing opening 49 and can again be suctioned through the cross-holes 55. Flexible air hoses 31 and 32 represent the connection to the corresponding compressed air generators or suction air generators (figures 1, 2a and 2b). Fig. 6a shows the end piece of the carrier plate 16 with its screwed in air nozzle 40, as well as a preform 10. The outer diameter DB on the air nozzle 40, in the region of the sealing ring 52, is smaller by a sufficient margin than a corresponding inner diameter Dip of the preform 10. From this we get, supported by the air flow forces, a centering effect for the preform 10 on the air nozzles or blowing mandrels 40. Figures 6d, 6e and 6f now show three different phases for the air guiding. In fig. 6d the blown air inlet is stopped. On the other hand, air from the inner side of the preform 10 is suctioned, so that an underpressure is generated in the inner space of the injection mould, whereby the preform forcefully gets centered on to the sealing ring 52 and is suctioned. In other words, in this way all preforms are held secure against the transfer device and can be brought to the subsequent air nozzles through corresponding swivel movement. Fig. 6e shows the other extreme situation. Here, a blown air beam 50 is blown with maximum possible strength on to the inner floor part of the preform 60, for effecting a correspondingly maximum possible cooling effect on this point. The blown air must compulsorily be suctioned off, so that a strong positive air current remains retained. From this we get a very important aspect, in which not only the preform floor 61 but also the preform threaded part 62 gets intensively cooled. So that the described maximum possible air cooling effect is possible, the preform must be held with mechanical forces mkl -18- and mk2. Fig. 6f shows a farther situation, in which air is blown in as well as suctioned off. Blown air and suctioned air can be adjusted in such a way, that in the inner portion in the preform 10 a light underpressure can be retained and the preform 10 can be suctioned by the air pressure forces LDk and hence also remain centred. Figures 7a to 7d and 8a to 8d show.the special adapters during handling from the removal device 11 to the transfer gripper 12 on the one hand, as well as from the transfer gripper 12 to the after-cooling unit 19 on the other side. In fig. 7a the preform 10 has been completely taken over by the removal device 11. So that all preforms 10 lie completely in the cooling sleeve 200 or the crowning 207, underpressure is set in the air chamber 27, which is indicated by the minus signs. The valve pin 204 is lifted, so that the underpressure works on the hemispherical, outer floor 10\ and sucks it.in completely into the crowning 207. ,The preforms are thus retained fixed in the cooling sleeves 200, uniformly till coming to a stop. In fig. 7 the air nozzles or centering mandrels now drive into the preforms 10 by advancing the holder plate 16. Suction air and blown air are activated as shown in fig. 6f In the air chamber 27 there is initially underpressure, After the blowing mandrels are completely driven in, the most intensive cooling phase (fig. 7c) begins, whereby from outside influence is excercised with water and from inside with the help of air as shown in fig. 6e, for a few seconds. After about five seconds, the air condition becomes reversed. In the air chamber 27 one suddenly switches to the overpressure (+), so that the preform 10 gets ejected and after the first ejection movement the valve pin 204 immediately shuts off the air flow-out cross-section. On the sides of the blowing mandrels 40 one coordinates by switching the pressure condition in the air chamber 27 to a vacuum as shown in fig. 60, so that the preform 10 is retained in maximum suction force on the blower mandrels 40. The impact force of the compressed air in the air chamber 27 supplements the suction force on the opposite side. In fig. 8a the subsequent phase is shown. The transfer gripper 12 stays with the carrier plate 16 before completion of the swivel movement, as indicated by arrow 70. At the same time, the carrier plate 16 begins to move in the direction on to the after-cooling 19 by activation of a pneumatic or hydraulic unit, and pushes the preform 10 into the cooling sleeves 200 of the after-cooling unit 19. The pushing-in of the preforms is not particularly bad to the extent that this takes place supported by the mechanical movement forces by the carrier plate 16 compulsorily. In the air chamber 27 one has switched the underpressure, so that simply by the suction forces of the underpressure in the air chamber 27 the preforms are also held tight -19- here in a rest position. Depending on the choice of cycle duration, the air cooling effect in the phase as shown in figures 8a to 8c can be optimised. The carrier plate 16 must again go back to the take over position (B in fig. 1). The blowing mandrels 40 go as shown in fig. 8c corresponding to arrow 72 from the preforms 10 and move towards arrow 73 in opposite direction to the fig. 8a again back into position B. In fig. 8c the preforms 10 in the cooling sleeves 200 are held tight still by the underpressure (-). Fig. 8d shows the ejection of the preforms 10 as the last act of after-cooling. As already mentioned before, between the situation as shown in figures 8c and 8d, there could be one, two or several moulding cycles, or after-cooling could correspondingly last long. For the ejection, one immediately switches to pressure in the air chamber 27, so that preforms 10 are ejected by the air pressure and are thrown off on to a belt 20. The after-cooling device 19 is processed as indicated by arrow 74 in the sense of what is shown in figures 2a and 2b. A partial objective of the new solution lies in making the after-cooling time independent as far as necessary from the actual moulding cycle. From this cycle, the after-cooling as shown in figures 9a and 9b has several parallely arranged rows 1,2,3,4. In the example shown, in one row there are respectively 12 cooling sleeves 200 for taking up one preform each. The cooling sleeve 200, depending on the conditions in the casting mould partitions, be arranged much more closer. Therefore not only several parallel rows, but also additionally a staggering of the rows is suggested, as one can see from the section shown in figures 9a and 9b, with the dimension data x respectively y. This means that for a first moulding cycle, the cooling pipes with number CD are used, and for a second moulding cycle the cooling pipes with number 2 are used. If in the example with four parallel rows, also all rows are filled with the number 4, then too the rows with number 1 , as described, are ejected first and thrown on to the conveyor belt 20. The rest follows in sequence through the entire production time. In the shown example, the total after-cooling time is approx. 4 times the moulding time. It is thereby important, that the cooling chambers 23 for the water cooling are arranged optimally, so that the water cooling in all cooling pipes takes place as uniformly and as effectively as possible. On the other hand, the air pressure conditions or underpressure conditions must be controllable row-wise in the after-cooling unit, so that at a particular point of time all rows 1 or 2 etc. can be simultaneously activated. The corresponding row arrangement is indicated in fig. 6a. 20 Fig. 10 shows as example the cyclic steps with respect to time. The horizontal bars 80 indicate the air cooling and the horizontal bars 81 indicate water cooling. The lowest time-data Trans.op denotes a first transfer operation R, a second S, a third T etc. Three transfer operations are shown and over correspondingly moulding times — 15 sees., each a moulding cycle 84 with a duration of respectively 15 sees. The reference sign 83 denotes ejection of the completely cooled preforms 10, which takes approx. 1 sec. The reference sign 82 indicates the removal of the semi-solid preforms 10 from the mould halves. One single, complete transfer operation is subdivided into the most important part-steps in the left upper figure portion. 85 indicates removal, 86 driving out, 87 transfer gripper/swiveiling, 88 cooling block, 89 loading of cooling block, 90 vacuuming of cooling block, 91 driving away of cooling block, 92 swivelling of transfer gripper. Under the reference signs, with the figures 0.5; 5.2 etc. an approx. time data in sees, is given for the individual steps. St. stands for the controlling agents for the plant or the corresponding functional unit. -21- WE CLAIM 1. A method for prodacing a large number of sleeve-shaped injection moulds (10) locked from one side with afloor (10'), which are removed from the moulds (8,9) after the injection sequence and after-cooled and thereby pushed into water cooling pipes (22,30,200) and then again ejected, and brought from a aemi-solid condition on opening of the mould halves (8,9) by means of water cooling into a shape-stable condition and men handed over for further transportation (20), characterized in that the injection moulds (10) are removed from the open moulds (8,9) by a removal device (11) and through a transfer gripper (12) handed over to an after-cooling device (19) and in a shape-stable condition handed over by the after-cooling device (19) to a former transportation (20), whereby the handing over of injection moulds (10) takes place wi& the help of air nozzles (40) for an inner cooling of the injection moulds (10), which is arranged on the transfer gripper (12). 2. Method as claimed in claim 1, wherein the injection moulds (10), for after-cooling with the help of air as compressed air or vacuum, is pushed into fee water cooling pipes (22,30,200) and again ejected, whereby lying opposite to the push-in end of the water cooling pipes (22,30,200) a controllable and monitarahle pressure chamber (27) and the inner space of the cooling pipes (22,30,200) adjustable elements are arranged which are designed as valve elements (204), preferably as piston elements, so mat by means of me valve effect the injection moulds can be auctioned and held securely with underpressure and in case of overpressure ejection of the injection moulds (10) can be supported. -22- 3. Method as claimed in claim 1 or 2, wherein to the water cooling pipes (22,30,200) on the side of the pressure chamber or underpressure chamber (27), a crowned floor part (207) is allocated, in such a way, that for the purpose of intensifying the water cooling effect the injection mould (10) with its hemispherical floor (10') is immersed in the crowned floor part (207) of the water cooling pipe (22,30,200) or is auctioned by the underpressure right till it comes to rest 4. Method as claimed in claim 3, wherein die crowned floor part (207) is connected to the water cooling pipe (22,30,200) without clearance, or is a part of the water cooling pipe (22,30,200) itself and has a passage opening with a valve pin (204) arranged therein in a shiftable manner, in such a way, that with underpressure in the pressure chamber a passage opening gets released to the inner portion of the water cooling pipe (22,30,200), and in case of overpressure in the pressure chamber (27) the ejection sequence for the injection mould (10) is supported, 5. Method as claimed in one of the claims 1 to 4, wherein for the region of the open push-in end (25) of fee water cooling pipes (22,30,200), the shiSable elements are designed as air nozzles (40), which are cyclically pushed into the injection moulds (10) and handling air is introduced into the inner portion of the injection mould (10) and/or suctions it off 6. Method as claimed in one of the claims 1 to 5, wherein a control system is provided which controls the transportation steps pulse-wise and coordinates the cooling phases cyclically, whereby particularly the movement cycles of the removal device (11) of the transfer gripper (12) and the after-cooling unit (19) are preferably adjustable independent of one another. 7. Method as claimed in claim 6, wherein the transfer unit takes over the injection moulds from the removal device (11) in a horizontal position with the help of the air nozzles (40) or centering mandrels, swivels these into a vertical position and push them into the water cooled(200)of the after-cooling unit (19). -23- 8. Method as claimed in claim 6 or 7, wherein during handing over of the injection mould (10) from the removal device (11), me air nozzles (40) atop in apuahed-in position for several seconds for the sake- of an intensive blow-cooling, particularly by the hemispherical base (10) of the inner side of the injection moulds (10). 9. Method as claimed in one of the claims 5 to 8, wherein the pressure conditions on both sides of the injection mould bases (10') can be independently controlled, so mat in a coordinated manner a blown air current and/or an underpressure condition is generated, and accordingly the injection moulds are retained by underpressure on the one or the other side, or can be ejected by the one or the other direction by means of pressure impact 10. Method as claimed in one of the claims 5 to 9, wherein the air nozzles (40) are designed as suck-and-blow mandrels, with suction openings for the region of the open end of the injection moulds, in such a way, that various operation conditions can be set in a controlled manner, e.g. a dominant air blowing beam in the region of the closed floor end (10) in the inner part of the injection moulds (10), or a strong vacuum efiect within the injection mould (10) or a mixed form between both 11. Method as claimed in claim 1, wherein the transfer gripper (12) and the removal device (11) are conceived for taking up an equal number of injection moulds (10), like the injection mould tool (8,9), whereby the after-cooling unit (19) has water-cooled sleeves (200) arranged in two or multiple rows or even staggered if necessary, ao that by corresponding transverse displacement and longitudinal displacement, the after-cooling unit (19) can take up two or several charges of injection moulds (10), for each injection mould cycle for reduction of the mould cycle time and increasing the after-cooling time. -24- 12. Method as claimed in one of the claims 1 to 11 wherein the phase of removal of the injection moulds (10) from the mould halves (8,9) and the complete handover to the after-cooling unit (19) is approximate to the time duration of moulding cycle and the total after-cooling time conforms to at least two or three times the moulding cycle time, and a double cooling can be undertaken from inside and outside on the injection moulds (10) during a significant part of fee moulding cycle time directly after removal of the injection moulds (10). 13. Method as claimed in one of the claims 1 to 12. wherein at least the ejection of the injection moulds (10) takes place supported by air pressure on the air side, and water cooling is supplemented at the end of the injection mould removal as well as at the beginning of after-cooling by means of air blowing nozzles (40) which can be mechanically shifted into the inner side of the injection moulds (10). 14. Injection moulding machine for production of sleeve-shaped injection moulds (10) closed on one side with a base (1'), consisting of a lock-up mechanism and opening mechanism, removal and after-cooling units (11,19), in which at least, corresponding to the number of injection moulds (10) produced per cycle, there are water cooling pipes (22,30,200) foreseen for the injection moulds (10)> whereby the push-in side for the injection moulds (10) are arranged lying opposite and a pressure and underpressure- chamber (27) is arranged connected with the cooling pipe take-up chamber for the injection moulds (10), wherein they have a transfer gripper (12), corresponding to the number of injection moulds (10) to be cooled, air nozzles (40) for an inner cooling of the injection moulds (10), through which the injection moulds (10) can be handed over from the removal device (11) into the after-cooling unit (19). -25- 15. Injection moulding machine as claimed in claim 14, ' wherein the air nozzles (40) are designed pushable into the inner portion of the respective injection moulds (10), whereby an opening of the air nozzles at the blowing mandrel tip can be positioned to almost on the base (10') of me injection moulds (10). 16. Injection moulding machine as claimed in claims 14 to 15, wherein the air nozzles (40) or blowing mandrels are arranged on aholder plate (15) and form as transfer gripper (12) an independently controllable component, whereby on the transfer gripper (12) fee blowing mandrels (14) are designed as centering mandrels, for taking over fee injection moulds (10) from the removal device (11) in a horizontal position and swiveiing it to a vertical position and subsequently pushing it into the water cooling pipes (200) of the after-cooling unit (19). 17. Injection moulding machine as claimed in claims 14 to 16, wherein it has a water-cooled removal device (11) and a transfer gripper (12) with an air cooling agent, as well as a water-cooled after-cooling unit (19) and a control unit (St.), through which the movement steps can be controlled pulse-wiEe and me cooling phases can be coordinated cyclically, in such a manner, that from the removal of the injection moulds (10) upto the ejection at me end of the after-cooling phase at least on? cooling can be activated without interruption. 18. Injection moulding machine as claimed in claims 14 to 17, wherein the after-cooling unit (19) can be shifted like a slide in a horizontal level from a exact take-over position above the transfer unit into an ejection position by means of a transportation belt (20) for taking up or ejection of the injection moulds (10) longitudinally and/or transversely. -26- 19. Injection moulding machine as claimed in claim 17, wherein foe transfer gripper (12) mid the removal device (11) can be equipped for taking up can equal number of injection moulds (10), like the injection moulding tool (8,9), and the after-cooling unit (19) has two or several rows of water-cooled sleeves (200) arranged parallely or staggered if required, so that by means of corresponding longitudinal andfor transverse shifting, the after-cooling device (19) can take up two or more charges of injection moulds (10) for each injection moulding cycle for reduction of the moulding cycle time and increasing the cooling time. 20. Injection moulding machine as claimed in claim 14, wherein at least one mechanically shiftable element for optimizing the air effect on each injection mould (10) is foreseen, whereby the shiftable elements are designed as valve pins (204), especially piston elements (103)* for economic ensuring of clear overpressure or underpressure conditions, in such a way, that the injection moulds (10) drawn by them into the cooling pipes (22,30,200) can be safely ejected on application of overpressure in the pressure chamber (27), and on switching to underpressure in the pressure chamber (27), an underpressure can be generated in a passage channel between pressure chamber and inner space of me cooling pipes (22,30,200), for suctioning the injection moulds (10). 21. Injection moulding machine as claimed in claim 14 or 15, wherein the water cooling pipes (22,30,200) on the side of the pressure chamber (27) have crowned base portions (207), suitable for corresponding hemispherical bases (10s) of the injection moulds (10), whereby the shiftable element is integrated in the form of a valve pin (204) in the crowned base portion (207). The aim of the invention is to improve the cooling or subsequent cooling range during the production of pre—shaped bodies for PET bottles, so—called preforms. Water cooling is primarily used for initial cooling and also during subsequent coaling. The air action, however, is improved by assigning mechanically displaceable elements to the air side action. As a result, the security with regard to malfunctions during handling as well as the cooling action can be improved. When combined, two especially advantageous embodiments yield an optimal solution. A valve-like element is provided for ejecting and an air nozzle 40 is provided for the interiorof the reforms, said nozzle assisting in the handling and cooling.

Full Text

Technical scope

A method producing a large number of a sleeve-shaped injection moulds
closed on side with a floor, which are removed from the moulds after the injection sequence and after-cooled and thereby pushed into water cooling pipes, and again ejected and brought from their semi-solid condition on opening the mould halves into a shape-stable condition by means of water cooling and then handed over for further transportation; besides, also an injection moulding machine for production of sleeve-shaped injection moulds closed on one side with a floor, consisting of a lock-in and opening mechanism, removal and after-cooling units, in which at least corresponding to the number of injection moulds produced per cycle, water cooling pipes are provided for the injection moulds, whereby a pressure or underpressure chamber is arranged lying opposite to the push-in side for the injection moulds and connected to the cooling pipe takeover chamber for the injection moulds.
State-of-the-art technology
During production of the typical thick-walled injection moulds of the above mentioned type, for the attainable cycle time, the cooling time, especially the after-cooling time is an important and a decisive factor. The main cooling still takes place in the casting mould halves. Both the casting mould halves are intensively water-cooled during the casting process, so that the temperature in the mould can be reduced from approx. 280° upto approx. 70° to 80° C, at least in the edge layers. 2/3 of the cooling performance thereby takes place over the core, 1/3 by external cooling of the corresponding injection moulds. In the outer layers the so called glass temperature of approx. 140° C is very rapidly conducted. The actual casting sequence till removal of the injection moulds can be reduced to approx. 13 to 15 sec, with optimum quality with reference to the still semi-solid injection moulds. The injection moulds must be strengthened to such an extent that these can be gripped only with relatively large forces of ejection aids and can be passed on to a removal fixture without deformation or damages. The removal fixture has a mould adapted to the injection moulds, so that during subsequent treatment the shape of the injection moulds can be retained exactly. The more

intensive water cooling in the casting mould halves takes place physically-conditioned and with respect to the enormous wall thickness, with a time lag, from outside to inside. This means that the temperature of 70° to 80° C is not achieved uniformly in the entire cross-section. The result is, that a rapid re-heating takes place from inside to outside, as. seen in the material cross-section, as soon as the intensive cooling effect is interrupted. The so-called after-cooling is very important due to two reasons. Firstly, any alteration in shape till the shape-stable condition, as well as surface damages, like pressure points etc. will have to be avoided. Secondly, it must be prevented that the cooling at higher temperature ranges takes place too slowly and that harmful crystal formation sets in locally due to re-heating. The objective is to have a uniformly amorphous condition, in the material of the cast mould. The surface of the injection moulds should no longer be sticky, as otherwise adhesive damages could occur in the relatively large boxes or packings where thousands of loose parts are poured in. Even in case of slight re-heating, the injection moulds should not exceed a surface temperature of 40° C.
Practice shows that the after-cooling after removal of the castings from the injection cast mould is precisely as important as the main cooling in the casting moulds. The expert caster knows that even minor errors could have huge effects. While testing new materials, especially during production interruption due to process errors, there could be situations that the hot injection moulds remains somewhat too long on the mandrel-like positive moulds. The result could be, that due to the continuing shrinkage process in the injection moulds caused by the cooling, it may not be possible to get this out any more with the normal ejectior forces of the machine and can be released from the moulds only with special auxiliary devices.
According to a first technique as per the state-of-the-art technology EP-PS 0 266 804, water is also used as cooling agent for after-cooling. The injection mould removed in semi-solid condition from the injection casting mould is cooled in water-cooled transportation and after-cooling units to such an extent, till a stable final condition is reached. The still semi-solid injection moulds are pushed into cooling cones surrounded by cooling water immediately after removal from the mould halves. In the last phase of the push-in sequence, the injection mould is totally pulled into the cooling cones with the help of underpressure and cooled there from outside. Application of the underpressure takes place through an air chamber or pressure chamber with which the inner space of the cooling sleeve opened on both sides is

4
directly connected. The inner contour of the cooling pipes is also relatively strongly conically shaped just like the outer contour of the sleeve-shaped injection mould. In this way the injection mould is at least theoretically constantly drawn during the cooling phase and the connected fading due to application of underpressure. In this way, an attempt is made to ensure that the injection mould remains in optimum cooling contact in the conical inner wall of the cooling cones. In practice, the projected ideal cooling contact is not always attainable. In a known solution, the injection moulds are after-cooled in lying position. In this case even small sticky points hinder the desired continuous drawing. After completing the concerned cooling phase or after achieving a shape-stable condition of the sleeve-shaped injection mould, the underpressure is switched off in the air chamber and overpressure is generated. All injection moulds are thereafter pushed out of the conical cooling sleeve like a piston by switching over to air overpressure.
A second technique, the so-called air cooling, is described in the document US-PS 4 592 719. There it is suggested that the production rate of the preforms be increased, in that instead of the separated after-cooling station, atmospheric air be used for cooling. The air is used as cooling air during transportation or "handling" by means of directed flow inside as well as outside on the preforms with maximum cooling effect. A removal unit, which has as many suction pipes as moulded parts produced in an injection cycle, drives in between both the open mould halves. The suction pipes are then pushed via the preforms. At the same time air begins to flow through a suction line in the region of entire circumferential area of the injection moulds surrounded by the suction pipes, so that from the moment of being taken over into the suction sleeve these are cooled by air from outside. The removal unit goes out of the movement space of the mould halves after complete takeover of all injection moulds of a casting cycle. The mould halves are then immediately free again for the subsequent casting cycle. The removal unit swivels the preforms after the driving out movement from a horizontal to a vertical position. Simultaneously a transfer unit runs in exactly to a handover position above the removal unit. The transfer unit has the same number of inner grippers as suction pipes of the removal units. Timely, after handover of all injection moulds, and before opening of the mould halves again, the removal unit is swung back into the drive-in position, so that the next charge of injection moulds can be removed from the moulds. The transfer unit hands over in the mean time the new, shape-stable injection moulds to a transporter and goes back without the preforms again into the takeover position for the next charge.

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The main disadvantage of the solution as per the document US-PS 4 592 719 is that the after-cooling time is so to speak unchangeably equal to the casting cycle time. Even if by means of suitable introduction of air one thus manages to reach even small increases of local air velocities and thus a certain reduction in time, the unchangeable physicality of the air cooling process is absolutely decisive for the production rate. An increase would only be possible by increasing the injection moulds produced per casting cycle in a multiple casting mould. This number is however restricted as a rule by the maximum press pressure of the injection moulding machine. The suggested technical method of cooling the preforms by air from inside as well as outside during removal and transportation, gives a system-caused restriction of the maximunTpossirJle quantities. The after-cooling time here restricts the performance capacity of the plant.
The document EP-PS 0 718,084 has three different devices: a removal device and a transfer device as well as an after-cooling device. The transfer gripper has a double function, as the pet-forms are brought into the after-cooling unit as well as again removed from it. It is suggested to do away with a cooling in the transfer device, in order to be able to carry out quicker movement on account of corresponding weight saving. Advantageous however is the simultaneous doing away with a direct cooling on the inner side of the pet-forms.

The subsequently published document EP 0 947 304 suggests a central cooling, an inner cooling with air by a combined device. The combination in a device includes the function of a transfer device, as well as an actual after-cooling from inside, till crystallisation is completely prevented in the inner side. A main cooling with the help of air is however less efficient than a cooling with a fluid medium.
The above mentioned water cooling method is however also subjected to certain restrictions. In practice it is however seen, that with water cooling for the same cavity number by reducing the cycle time, much larger number of injection moulds can be produced, assuming of course that ideal conditions can be maintained. The cavities of the injection casting moulds could have irregularities, which leads to differences in the outer contour of the sleeve-shaped injection moulds. In the same way, not all inner contours of the cooling sleeves are exactly same. This leads to the fact that some of the sleeve-shaped injection moulds after completion of the cooling phase, already slide out of the cooling sleeve due to self-weight, but other sleeve-shaped injection moulds remain in the cooling pipes or even get stuck there. In such a

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situation the blow pressure in the pressure chamber reduces due to the already emptied cooling pipes to the surrounding pressure level and is then no longer sufficient to push out the injection moulds remaining in some of the cooling pipes. This leads to an interruption upto the subsequent production cycle. Because the sleeve-shaped injection moulds remaining in some of the cooling pipes block the takeover of new injection moulds, these will have to be removed manually.
Summaryof the invention
It is the task of the invention to improve upon an injection moulding machine or corresponding method for production of sleeve-shaped injection moulds in such a way, that while guaranteeing an optimum cooling effect, the productivity can be increased, and especially an interruption of the production cycle, e.g. due to stuck injection moulds can be almost ruled out.
The method as per the invention has the feature. that,the injection moulds are removed by a removing device from the open moulds and handed over to an after-cool ing unit by a transfer gripper, and in the shape-stable condition handed over by the after-cooling unit for further transportation, whereby the handover of the injection moulds takes place through air nozzles for an inner cooling of the injection moulds, which are arranged on the transfer gripper.
The device as per the invention has the feature, that it has a transfer gripper with air nozzles for an inner cooling of the injection moulds corresponding in number to the injection moulds to be cooled, through which the injection moulds can be handed over by the removal device into the after-cooling unit.
It has been recognised by the inventors that in the described state-of-the-art technology, the restriction of maximum possible production is somewhat self-imposed due to the "purity of the applied method". A totally mixed system is naturally not possible, as on one side simultaneously only one cooling-medium, air or water can be used. If however both mediums are specifically used with their own advantages, then only one can reach the optimum condition. The new solution is based on the very efficient water cooling, however also centrally uses the air forces by using mechanically adjustable elements improving the air-side

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enect. Thus at the same time two new part-solution possibilities emerge, namely the effect at the level of air pressure as well as the level of air flow as cooling support. The investigations on,the basis of new invention have brought new findings to light. On the basis of the casting process it must follow, that the inner cooling with water is twice as sufficient as compared with outer cooling water. This statement however holds good only for the casting phase. For the after-cooling phase, due to a large number of reasons, preference is given to outer cooling with water. A very important reason is the parallel process of cooling and shrinking. If the more intensive cooling takes place from outside, then the preforms get released from the cooling sleeves lying outside. The opposite case would be very disadvantageous in this connection, as then one has the danger that the individual sleeve-shaped injection moulds could get stuck to the cooling mandrels. The shrinking process has the disadvantages in the first case, that the casting mould gets released more and more from the walling and direct cooling contact gets diminished and hence the cooling effect could become worse. This disadvantage comes to the fore, if the casting moulds get stuck in one and the same cooling pipe during the entire phase of after-cooling. As will be shown later, the new invention allows here also an improvement by "re-inserting'1 the casting moulds twice or several times in a correspondingly conceived after-cooling unit.
Another problem area was identified regarding the thick walls, mainly however in the region of the base of the injection mould sleeves. In the solutions of the state-of-the-art technology of water cooling, this zone is significantly difficult to attain. Here, ways and means were looked for, in order to improve this particularly critical point. In respect to the task, namely increase in productivity with maximum possible product quality, at the same time a decoupling of the hitherto strong bond of casting cycle and after-cooling was endeavoured. The new invention now allows a large number of particularly advantageous design forms with respect to the task in question or the problems encountered.
Lying opposite to the push-in end of the water cooling pipes, as in the state-of-the-art technology, a controllable pressure or underpressure chamber is foreseen. According to the new solution however, the pressure chamber is lockable with respect to the inner chamber of the cooling pipes, and is designed with adjustable elements, e.g. designed as valve elements or piston elements. Due to the valve effect, the injection moulds are suctioned in case of underpressure and held safe. In case of overpressure in the pressure chamber, the ejection of injection moulds is supported.

8
In the state-of-the-art technology, the injection mould forms along with the entire cross-section surface at the same time the locking piston of a valve. In the suction phase, simultaneously, e.g. 96 injection moulds are suctioned. Because each injection mould in itself forms a plug with the locked base and the larger diameter of the open threaded side with respect to the water cooling pipes, further suction air is stopped. The underpressure generated on the opposite side is retained till reversing. If now instead of underpressure an overpressure is generated, then simultaneously all 96 injection moulds are ejected due to air pressure effect. If the simultaneity of ejection is not possible, because one part flies out of the cooling sleeve faster, then in the state-of-the-art technology the air pressure collapses. Each time there is the danger, that for the particular preforms which can only be driven out with difficulty, the remaining air pressure will no longer be sufficient. According to the new solution, an additional auxiliary valve with significantly smaller, free flow cross-section is allocated to each injection mould. If for example, only half of the pieces are immediately ejected, then in this way the air pressure can be retained for the remaining ones or even increased. The auxiliary valve locks the passage in the water cooling pipe in an air-tight manner after the concerned injection mould has been ejected.
According to a further, particularly advantageous design form, to the water cooling pipe on the side of the pressure or underpressure chamber a crowning base part is allocated in such a way, that for the purpose of intensifying the water cooling effect the injection mould with its hemispherical floor is immersed in the crowning floor part of the water cooling pipe or is sucked into the bulge due to the underpressure. Ideally, a bulging floor part is connected to each of the water cooling pipes without any clearance, or it could even be part of the water cooling pipes. In a small average passage opening, an adjustable valve pin is arranged. Experiments have shown that in case of the cone solution, two very important aspects have been overlooked so far. Firstly, a particularly critical part is the entire region of the injection mould floor. The desired continuous drawing presupposes that the injection mould is not on the floor right from the beginning. The consequence is that the floor of the injection mould is either not cooled at all or only insufficiently. The second aspect is, that at a temperature of 70 to 80° C the radiation part is still relatively high. Even if a slight clearance sets in on the outside after a few seconds due to shrinkage, this is not very serious at the beginning of the after-cooling. The cooling gain due to the contact surface in the floor region weighs more

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than the slight loss on the circumferential surface. In addition to that, now the conicalness of the injection mould can remain restricted to the purely casting-technical requirement.
According to a second very advantageous design form, for the region of the open push-in end of the water cooling pipes, the adjustable elements are designed as air nozzles, which are cyclicly pushed in into the injection moulds, and bring handling air into the inner side of the injection mould and/or can suction them off. In this way it has been possible to bring the cooling effect, particularly in combination with the above described outer flow cooling to a maximum effect, even in the zone, which according to the state-of-the-art technology was the bottleneck for cooling. This is above all applicable, if the inner cooling air is blown into the proximity of the floor.
The entire range of after-cooling should preferably be designed in three stages, and has a removal device, a transfer gripper as well as an after-cooling unit. The air nozzle should preferably be part of the transfer gripper and as are designed as centring mandrel to hand over theinjectio'fi moulds from the removal unit to the after-cooling unit. A control is foreseen, which coordinates pulse-wise the transport steps and cyclically the cooling phases. The movement cycles or process intervention of the removal unit, the transfer gripper as well as the after-cooling unit can be adjusted independently for optimisation of the process or for production of a new product or for new product quality. The transfer unit takes over with the help of the air nozzles or centring mandrels the injection moulds from the removing gripper in a horizontal position With-a swinging-movement, the injection moulds are brought to a vertical position and pushed into the water-cooled sleeves of the after-cooling unit. During handover of the injection moulds from the removing gripper, ..the air nozzles preferably remain in a pushed-in position for several seconds. In this way, one gets the intensive blow cooling of particularly the semi-circular floor of the inner side of the injection mould. In this phase, the injection mould gets cooled from inside and from outside, i.e. double-side.
With the new solution, the air effect is utilized in the best possible way in different ways, whether it is as cooling agent or by means of forces of pressure or underpressure. In this way, the so-called handling as well as the solidification phase gets significantly improved. The pressure conditions and the flow conditions are independently controlled on both sides with reference to the injection mould floors. In a coordinated manner, a blow-air flow and/or an underpressure condition is generated, so that accordingly the injection moulds can be retained

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by underpressure on one or the other side, or through a pressure impact can be moved in one or the other direction. The air nozzles are preferably designed as suck-and-blow mandrels, with suction openings for the region of the open end of the injection moulds. Various operation conditions can be adjusted, e.g. a dominant air blow radiation in the region of the closed floor end in the inner part of the injection moulds, or a strong vacuum effect within the injection mould or a mixed form between both. This is particularly advantageous because the totally different phases can go into one another without time loss and partly also optimally overlap one another. This means that in the after-cooling phase the subsequent step can already begin, before the previous one has been totally completed. The transfer gripper and the removal unit are conceived for taking up of equal number of injection moulds, like the injection tool. On the other hand, the after-cooling unit has water cooling pipes preferably arranged parallel in two or multiple rows, or if required even arranged staggered. By corresponding cross-shifting and longitudinal shifting, the after-cooling unit can take up two or several charges of injection moulds for each injection moulding cycle for reducing the moulding cycle time and increasing the after-cooling time. By means of the measures described, the new solution allows a significant increase in efficiency. The phase of removal of the injection moulds from the mould halves and the complete hand over to the after-cooling unit approximately conforms to the time duration of a moulding cycle reduced to a minimum. The total after-cooling time can however be taken to twice or thrice the moulding cycle time. The new solution thereby allows specifically in certain phases a double cooling from inside and outside on the injection moulds, that too during a significant portion of the moulding
cycle time immediately after removal the injection moulds from the mould halves. For large

number of very advantageous rurtner design forms of the device, will be discloused in the following pages.
The invention further pertains to the application of the method for the area of injection mould removal and/or for the area of after-cooling, whereby at least the ejection of the injection moulds by air pressure.through an adjustable valve element can take place supported from the air side, and the water cooling effect at the end of the injection mould removal as well as at the beginning of the after-cooling is supplemented by the air blow nozzles which can be mechanically adjusted in the interior of the injection mould.
The invention further pertains to application of adjustable valve pins for supporting the ejection effect of compressed air and/or blow-mandrels, which can be adjusted in the inner

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side of the injection moulds, for supporting the cooling effect primarily on the floor regions of the injection moulds for use in the removal device as well as the after-cooling unit, in case of injection moulding machines.
Short description of the invention
The invention is explained below with a few design example, as well as accompanying schematic drawings.
The following are shown:
Fig. 1 Schematically, a complete injection moulding machine with removal-,
transfer- and after-cooling units for the injection moulds;
Fig.2a and 2b Two different handling or handover situations for preforms;
Fig.3 A known solution as per the state-of-the-art technology for water
cooling of preforms;
Fig.4 An example of a solution according to the new invention;
Fig. 5a, 5b and 5c A particularly interesting design form of the solution with respect to outer cooling and drawing in or ejection of the injection moulds;
Fig.6a to 6f Different parts and dispositions for the inner cooling by means of air
nozzles or centering mandrels;
Fig. 7a to 7d Different handling situations between removal gripper and transfer
gripper;
Fig. 8a to 8d Different handling situations between transfer gripper and after-cooling
unit;
Fig.9a and 9b A section or cutout of the after-cooling unit;
Fig. 10 Schematically, the different cycles during production of preforms.

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Ways and execution of the invention
Figures 1 as well as 2a and 2b show an entire injection moulding machine for preforms with a machine bed 1, on which a fixed mould clamping plate 2 and an injection unit 3 are supported. A support plate 4 and a movable mould clamping plate 5 are axially shifable on the machine bed 1. The fixed mould clamping plate 5 and the support plate 4 are connected to one another by means of four booms 6, which go through the movable mould clamping plate 5 and guide it. Between the support plate 4 and the movable mould clamping plate 5 there is a drive unit 7 for generating the locking pressure. The fixed mould clamping plate 2 and the movable mould clamping plate 5 each carry a mould half 8 and 9, in which respectively a large number of part-moulds 8' and 9' and arranged, which together form cavities for generating a corresponding number of sleeve-shaped injection moulds. The part-moulds 8' are designed as mandrels, on which after opening of the mould halves 8 and 9 the sleeve-shaped injection moulds 10 adhere to. The injection moulds are at this point still in a semi-solid condition and are indicated by interrupted lines. The same injection moulds 10 in completely cooled condition are shown in fig. 1 in left top, where they are being ejected out of an after-cooling unit 19. The upper booms 6, for the purpose of better depiction of the details between the open mould halves, are shown interrupted.
In the figures 2a and 2b, the four most important handling phases for injection moulds after completion of the moulding process are shown:
"A" is the removal of the injection mould of preforms 10 from both the mould halves. The still semi-solid sleeve-shaped parts are thereby taken up by a removal unit 11 in the space between the open mould halves and sunk into the position "A", and with the help of this lifted to the position "B" (takeover device 11' in fig. 1).
"B" is the handover position of the removal unit 11 with the preforms 10 on to a transfer gripper 12 ("B" in fig. 1).
"C" is the handover of the preforms 10 from the transfer gripper 12 on to a after-cooling unit 19.
"D" is the ejection of the cooled preforms brought to a shape-stable condition, from the after-cooling unit 19.
Fig. 1 shows so-called snap shots of the four main steps for handling. In position "B" the sleeve-shaped injection moulds 10 arranged lying vertically above one another, are taken over

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by the transfer gripper 12 or 12' and by swivelling the transfer unit in the direction of the arrow P brought to a position standing horizontally beside one another, according to the phase "C" .The transfer gripper 12 consists of a holding arm 14 swivellable around an axis 13, which carries a holder plate 15, to which a carrier plate 16 for the centering mandrel 8" is arranged in parallel distance. The carrier plate 16 can be adjusted parallel to the holder plate 15 by means of two hydraulic units 17 and 18, so that in the position "B" the sleeve-shaped injection moulds 10 can be brought out of the removing unit 11 and pushed into the after-cooling unit 19~lying above in the swivelled position "C". The respective handover takes place by increasing the distance between the holder plate 15 and the carrier plate 16. The still semi-solid sleeve-shaped injection moulds 10 are completely cooled in the after-cooling unit 19 and subsequently after shifting the after-cooling unit 19 in the position "D" can be ejected and thrown on to a conveyor belt 20.
In figures 2a and 2b two situations with the respective cooling intervention mediums are similarly schematically depicted. In fig. 2a both the mould halves 8 and 9 are in closed condition, i.e. shown in the actual moulding phase, with connecting hoses for the cooling agents. Thereby "water'7 denotes water cooling and "air" the air impact. The maximum temperature reduction from 280° C to 80° C for the injection moulds 10 takes place within the closed moulds 8 and 9, for which an enormous amount of cooling water passage has to be ensured. The removal device 11 is in fig. 2a already in waiting position, which indicates the end of the injection phase. The reference sign 30 is the water cooling with corresponding inlet and outlet pipes, which for the case of simplicity have been indicated with arrows and are presumed to be known. The reference signs 31/32 denote the air sides, 31 stands for bfowing-in or compressed air feeding and 32 stands for vacuum or air suction. With that, one can already recognize at the principle level the application possibilities of air and water. In the injection casting moulds 8 and 9, during the injection moulding process, a pure water cooling takes place. In the removal device 11, air as well as water is used. In the transfer gripper or removal gripper 12 there is only an air effect. On the other hand, in the after-cooling device 19, again air and water are used. Fig. 2b shows the beginning of the removal of the preforms 10 from the open mould halves. Not shown are the auxiliary agents for pushing off the semi-solid preforms from the part-moulds 8'. A further important point is the handling in the region of after-cooling device. The after-cooling device can be horizontally driven in the direction of the arrow L independently during the removal phase "A", from a taking up position (shown in fig. 2b with drawn out lines) into an ejection position (shown

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dashed). This working step is indicated in fig. 2 "C/D". As explained with the figures 9a and 9b, the after-cooling device 19 could have several times the holding capacity as compared to the number of cavities in the injection.casting mould halves. Ejection of the completely cooled preforms 10 can take place only after two, three or more injection moulding cycles, so that the after-cooling time would have to be correspondingly extended. For handing over the preforms from the transfer gripper 12 to the after-cooling device 19, the latter can additionally be set in the suitable position as indicated by arrow a, i.e. transversely shifted.
Fig. 3 shows a cutout of a cooling device as per the state-of-the-art technology with a cooling block 21, in which several cooling sleeves 22 (filled black) are arranged. The cooling block 21 and the cooling sleeves 22 enclose a holow space 23, through which cooling water (marked dashed) flows. The inner space 24 of the cooling sleeves 22 serves the purpose of taking up sleeve-shaped injection moulds 10 and is conically tapered upward. At the lower end of the cooling sleeve there is an inlet and outlet opening 25, through which the still semi-solid injection moulds are introduced and from which the completely cooled injection moulds 10 are pushed out. At the upper end of the cooling sleeve 22 there is an opening 26 to an air chamber 27, which is surrounded by a cover 28. The sleeve-shaped injection moulds 10 represent so-called preforms for production of PET-jars, whereby in the left cooling sleeve a preform of size ??PF 30 x 165 and in the central cooling sleeve a shorter preform of size PF (j) 30 x 120 is arranged. The still semi-solid injection moulds are completely drawn in after pushing into the cooling sleeves on account of an underpressure existing with air chamber 27, so that injection mould comes in close cooling contact with the inner surface of the cooling sleeve 22. After completion of the cooling sequence, the now solid and shape-stable injection moulds are pushed out by means of applying overpressure from the air chamber 27. In this cooling device as per the state-of-the-art technology, as shown in fig. 3, there is the problem, that on account of irregularities in the production of mould cavities for the injection mould and the inner contour of the cooling sleeves, one or several injection moulds get blocked or could fall out of the cooling sleeve already towards the end of the cooling phase due to their self-weight. This is particularly applicable for the solution in which a cooling device as shown in fig. 3, is brought into a horizontal position for ejection. If in the air chamber one switches from underpressure to overpressure, in order to push out the completely cooled injection mould, on account of the large flow cross-sections due to prematurely released cooling sleeves 22' there could be insufficient pressure for pushing out the remaining

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injection moulds. The production cycle is interrupted by not-emptied cooling sleeves, till all sleeves are manually released if required.
Figures 4, 5a and 5b show design forms, in which as per the invention a simultaneous ejection of all injection moulds 10 at the end of the cooling phase is ensured. The design form as shown in fig. 4 shows a cooling sleeve 100, which has a tube-shaped connecting piece 101 at its upper end, which goes into the air chamber 27. The inner diameter 101' of the connecting piece 101 is greater than the inner space 102 of the cooling sleeve 100. In the connecting piece 101 there is a mechanically shiftable element in the form of a piston 103, whose outer diameter is lesser by a sufficient margin than the inner diameter 101' of the connecting piece 101, so that a defined air clearance is given. This air clearance forms a throttled passage channel 104 between the inner space of the cooling sleeve 100 and the air chamber 27. The transition from the larger inner space of the connecting piece 101 to the smaller space of the cooling sleeve 100 is designed in the shape of a valve seat ring 105, for which the piston 103 has a fitting valve seat ring 106. In the cooling phase, the injection mould 10 with its hemispherical floor 10' drawn into the cooling sleeve 100 lands above the valve seat ring 105 into the connecting piece 101. On application of underpressure of the air chamber 27 the underpressure branches over the passage channel 104 into the inner space of the cooling sleeve 100 and effects a drawing-in of the injection mould 10 into the cooling sleeve 100. After completion of the cooling phase, in the air chamber 27 one switches from underpressure to overpressure. The injection mould is ejected by the air pressure out of the cooling sleeve, whereby the piston element 103 moves downward. On impact of the piston 103 against the valve seat ring 105, on the one hand, the movement of the piston 103 is restricted, on the other hand, any kind of air exit from the air chamber 27 through the corresponding cooling sleeve is stopped. Before the subsequent filling of the cooling sleeve 100 with new, still semi-solid injection moulds 10, the piston 103 is again lifted up by the underpressure of the air chamber 27, whereby simultaneously the ring-shaped passage channel between piston 103 and inner walling of the connecting piece 101 is again opened, so that the underpressure in the inner space of the cooling sleeve 100 continues to branch out and the complete drawing-in of the injection moulds 10 can be effected. The design forms as shown in 5a and 5b show a preferred design with a cooling sleeve 200, which has a connecting piece 201 at its upper end, which is provided with a locking body 203 having a guide opening 202. This is provided in the lower region in a crowning 207, into which the injection mould 10 with its hemispherical flow gets immersed. In the guide opening 202 a thin piston element in the form of a valve pin

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204 is guided in a mechanically shiftable manner in an axial direction, whereby in the cylindrical passage opening 202 a passage channel 202' is designed in the form of grooves. The grooves (on the right side of fig. 5b) represent through-passages for an air exchange between the air chamber 27 and inner space of the cooling sleeve 200 within the crowning 207, and ensure a pressure exchange (as overpressure or underpressure) between the chamber 27 and the inner side of the cooling sleeve 200 (within the crowning 207). On the side towards the air chamber 27 of the through-opening 202, there is a truncated cone-shaped extension 205 into which the valve pin 204 with a correspondingly designed cone-shaped valve seat 206 can come to rest in a sealing manner (left side in fig. 5b with drawn-out lines). For filling the cooling sleeves 200 with the still semi-solid injection mould 10, by means of the underpressure of the air chamber 27 the valve pin 204 is drawn upward (fig. 5b right side). The underpressure branches off from the air chamber 27 through the grooves 202' in the passage opening 202 to the inner space of the cooling sleeve 200 and effects the complete drawing-in of the injection mould 10 (fig. 5a left side). After completion of the cooling phase, one switches from underpressure to overpressure in the air chamber 27. The valve pin 204 follows mechanically the completely cooled injection mould for short paths. The displacement path of the valve pin 204 is limited by the impact of its cone-shaped valve seat 206 on the truncated cone-shaped extension 205 of the passage opening 202 and a further passage of compressed air from the air chamber 27 to the inner space of the cooling sleeve is blocked. A residual pressure air cushion between the inner crowning 207, the cooling sleeve 200 as well as the outer hemispherical floor 10' effects as a result a complete ejection of the injection moulds 10 with corresponding air pressure. With the design forms according to the new solution it is ensured that in case of overpressure of the air chamber 27, the overpressure in the air chamber 27 remains constantly retained at the required magnitude, or can even be increased and all injection moulds 10 can be subjected to a maximum ejection force after completion of the cooling sequence.
In fig. 6c an air nozzle 40 is shown. The air nozzle 40 is denoted below, depending on its respective function, as blowing mandrel or centering mandrel. The air nozzle 40 has a worm 41 on the left side, with which the air nozzles 40 are screwed on to the carrier plate 16. As shown in fig. 1, the carrier plate 16 has a large number of air nozzles 40, which are respectively arranged in several rows. In the carrier plate 16, as shown in fig. 6a, there are two air channel systems 42 and 43, whereby the air system 42 is designed for underpressure or vacuum (fig. 6d), and the air system 43 is designed for compressed air (fig. 6e), with

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corresponding, not-shown connections for a compressed air generator or a suction blower or a vacuum pump. So that both air systems can be clearly separated, there are special bolts 43, 44 and 45 with necessary recesses on the adapters for mounting as well as penetration of the respective connecting pieces. The special bolts 43, 44 and 45 must compulsorily be screwed in or out in the correct sequence. In the completely mounted condition, both the air systems must be sealed against one another and should be able to fulfil their own functions. For the compressed air side a blower tube 47 corresponding to the length "1" must be pushed-in in the right mounting sequence, and guides the blown air through a hole 48 in the air nozzle 40 upto the blowing opening 47, from where a blowing air beam 50 blows out. For fixed screwing of the worm 41, a hexagonal wrench 51 is connected to the air nozzle 40, and a sealing ring 52 on the opposite side. The suction air connection 53 goes through a ring channel 54 as well as several cross-holes 55, which close to the sealing ring 52 connect the ring channel 54 on the outer side. From this we obtain, that air can be blown out through the blowing opening 49 and can again be suctioned through the cross-holes 55. Flexible air hoses 31 and 32 represent the connection to the corresponding compressed air generators or suction air generators (figures 1, 2a and 2b).
Fig. 6a shows the end piece of the carrier plate 16 with its screwed in air nozzle 40, as well as a preform 10. The outer diameter DB on the air nozzle 40, in the region of the sealing ring 52, is smaller by a sufficient margin than a corresponding inner diameter Dip of the preform 10. From this we get, supported by the air flow forces, a centering effect for the preform 10 on the air nozzles or blowing mandrels 40. Figures 6d, 6e and 6f now show three different phases for the air guiding. In fig. 6d the blown air inlet is stopped. On the other hand, air from the inner side of the preform 10 is suctioned, so that an underpressure is generated in the inner space of the injection mould, whereby the preform forcefully gets centered on to the sealing ring 52 and is suctioned. In other words, in this way all preforms are held secure against the transfer device and can be brought to the subsequent air nozzles through corresponding swivel movement. Fig. 6e shows the other extreme situation. Here, a blown air beam 50 is blown with maximum possible strength on to the inner floor part of the preform 60, for effecting a correspondingly maximum possible cooling effect on this point. The blown air must compulsorily be suctioned off, so that a strong positive air current remains retained. From this we get a very important aspect, in which not only the preform floor 61 but also the preform threaded part 62 gets intensively cooled. So that the described maximum possible air cooling effect is possible, the preform must be held with mechanical forces mkl

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and mk2. Fig. 6f shows a farther situation, in which air is blown in as well as suctioned off. Blown air and suctioned air can be adjusted in such a way, that in the inner portion in the preform 10 a light underpressure can be retained and the preform 10 can be suctioned by the air pressure forces LDk and hence also remain centred.
Figures 7a to 7d and 8a to 8d show.the special adapters during handling from the removal device 11 to the transfer gripper 12 on the one hand, as well as from the transfer gripper 12 to the after-cooling unit 19 on the other side. In fig. 7a the preform 10 has been completely taken over by the removal device 11. So that all preforms 10 lie completely in the cooling sleeve 200 or the crowning 207, underpressure is set in the air chamber 27, which is indicated by the minus signs. The valve pin 204 is lifted, so that the underpressure works on the hemispherical, outer floor 10\ and sucks it.in completely into the crowning 207. ,The preforms are thus retained fixed in the cooling sleeves 200, uniformly till coming to a stop. In fig. 7 the air nozzles or centering mandrels now drive into the preforms 10 by advancing the holder plate 16. Suction air and blown air are activated as shown in fig. 6f In the air chamber 27 there is initially underpressure, After the blowing mandrels are completely driven in, the most intensive cooling phase (fig. 7c) begins, whereby from outside influence is excercised with water and from inside with the help of air as shown in fig. 6e, for a few seconds. After about five seconds, the air condition becomes reversed. In the air chamber 27 one suddenly switches to the overpressure (+), so that the preform 10 gets ejected and after the first ejection movement the valve pin 204 immediately shuts off the air flow-out cross-section. On the sides of the blowing mandrels 40 one coordinates by switching the pressure condition in the air chamber 27 to a vacuum as shown in fig. 60, so that the preform 10 is retained in maximum suction force on the blower mandrels 40. The impact force of the compressed air in the air chamber 27 supplements the suction force on the opposite side.
In fig. 8a the subsequent phase is shown. The transfer gripper 12 stays with the carrier plate 16 before completion of the swivel movement, as indicated by arrow 70. At the same time, the carrier plate 16 begins to move in the direction on to the after-cooling 19 by activation of a pneumatic or hydraulic unit, and pushes the preform 10 into the cooling sleeves 200 of the after-cooling unit 19. The pushing-in of the preforms is not particularly bad to the extent that this takes place supported by the mechanical movement forces by the carrier plate 16 compulsorily. In the air chamber 27 one has switched the underpressure, so that simply by the suction forces of the underpressure in the air chamber 27 the preforms are also held tight

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here in a rest position. Depending on the choice of cycle duration, the air cooling effect in the phase as shown in figures 8a to 8c can be optimised. The carrier plate 16 must again go back to the take over position (B in fig. 1). The blowing mandrels 40 go as shown in fig. 8c corresponding to arrow 72 from the preforms 10 and move towards arrow 73 in opposite direction to the fig. 8a again back into position B. In fig. 8c the preforms 10 in the cooling sleeves 200 are held tight still by the underpressure (-). Fig. 8d shows the ejection of the preforms 10 as the last act of after-cooling. As already mentioned before, between the situation as shown in figures 8c and 8d, there could be one, two or several moulding cycles, or after-cooling could correspondingly last long. For the ejection, one immediately switches to pressure in the air chamber 27, so that preforms 10 are ejected by the air pressure and are thrown off on to a belt 20. The after-cooling device 19 is processed as indicated by arrow 74 in the sense of what is shown in figures 2a and 2b.
A partial objective of the new solution lies in making the after-cooling time independent as far as necessary from the actual moulding cycle. From this cycle, the after-cooling as shown in figures 9a and 9b has several parallely arranged rows 1,2,3,4. In the example shown, in one row there are respectively 12 cooling sleeves 200 for taking up one preform each. The cooling sleeve 200, depending on the conditions in the casting mould partitions, be arranged much more closer. Therefore not only several parallel rows, but also additionally a staggering of the rows is suggested, as one can see from the section shown in figures 9a and 9b, with the dimension data x respectively y. This means that for a first moulding cycle, the cooling pipes with number CD are used, and for a second moulding cycle the cooling pipes with number 2 are used. If in the example with four parallel rows, also all rows are filled with the number 4, then too the rows with number 1 , as described, are ejected first and thrown on to the conveyor belt 20. The rest follows in sequence through the entire production time. In the shown example, the total after-cooling time is approx. 4 times the moulding time.
It is thereby important, that the cooling chambers 23 for the water cooling are arranged optimally, so that the water cooling in all cooling pipes takes place as uniformly and as effectively as possible. On the other hand, the air pressure conditions or underpressure conditions must be controllable row-wise in the after-cooling unit, so that at a particular point of time all rows 1 or 2 etc. can be simultaneously activated. The corresponding row arrangement is indicated in fig. 6a.

20
Fig. 10 shows as example the cyclic steps with respect to time. The horizontal bars 80 indicate the air cooling and the horizontal bars 81 indicate water cooling. The lowest time-data Trans.op denotes a first transfer operation R, a second S, a third T etc. Three transfer operations are shown and over correspondingly moulding times — 15 sees., each a moulding cycle 84 with a duration of respectively 15 sees. The reference sign 83 denotes ejection of the completely cooled preforms 10, which takes approx. 1 sec. The reference sign 82 indicates the removal of the semi-solid preforms 10 from the mould halves. One single, complete transfer operation is subdivided into the most important part-steps in the left upper figure portion. 85 indicates removal, 86 driving out, 87 transfer gripper/swiveiling, 88 cooling block, 89 loading of cooling block, 90 vacuuming of cooling block, 91 driving away of cooling block, 92 swivelling of transfer gripper. Under the reference signs, with the figures 0.5; 5.2 etc. an approx. time data in sees, is given for the individual steps. St. stands for the controlling agents for the plant or the corresponding functional unit.

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WE CLAIM
1. A method for prodacing a large number of sleeve-shaped injection moulds (10)
locked from one side with afloor (10'), which are removed from the moulds (8,9) after
the injection sequence and after-cooled and thereby pushed into water cooling pipes
(22,30,200) and then again ejected, and brought from a aemi-solid condition on opening
of the mould halves (8,9) by means of water cooling into a shape-stable condition and
men handed over for further transportation (20),
characterized in that
the injection moulds (10) are removed from the open moulds (8,9) by a removal device (11) and through a transfer gripper (12) handed over to an after-cooling device (19) and in a shape-stable condition handed over by the after-cooling device (19) to a former transportation (20), whereby the handing over of injection moulds (10) takes place wi& the help of air nozzles (40) for an inner cooling of the injection moulds (10), which is arranged on the transfer gripper (12).
2. Method as claimed in claim 1,
wherein the injection moulds (10), for after-cooling with the help of air as compressed air or vacuum, is pushed into fee water cooling pipes (22,30,200) and again ejected, whereby lying opposite to the push-in end of the water cooling pipes (22,30,200) a controllable and monitarahle pressure chamber (27) and the inner space of the cooling pipes (22,30,200) adjustable elements are arranged which are designed as valve elements (204), preferably as piston elements, so mat by means of me valve effect the injection moulds can be auctioned and held securely with underpressure and in case of overpressure ejection of the injection moulds (10) can be supported.

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3. Method as claimed in claim 1 or 2,
wherein to the water cooling pipes (22,30,200) on the side of the pressure chamber or underpressure chamber (27), a crowned floor part (207) is allocated, in such a way, that for the purpose of intensifying the water cooling effect the injection mould (10) with its hemispherical floor (10') is immersed in the crowned floor part (207) of the water cooling pipe (22,30,200) or is auctioned by the underpressure right till it comes to rest
4. Method as claimed in claim 3,
wherein die crowned floor part (207) is connected to the water cooling pipe (22,30,200) without clearance, or is a part of the water cooling pipe (22,30,200) itself and has a passage opening with a valve pin (204) arranged therein in a shiftable manner, in such a way, that with underpressure in the pressure chamber a passage opening gets released to the inner portion of the water cooling pipe (22,30,200), and in case of overpressure in the pressure chamber (27) the ejection sequence for the injection mould (10) is supported,
5. Method as claimed in one of the claims 1 to 4,
wherein for the region of the open push-in end (25) of fee water cooling pipes (22,30,200), the shiSable elements are designed as air nozzles (40), which are cyclically pushed into the injection moulds (10) and handling air is introduced into the inner portion of the injection mould (10) and/or suctions it off
6. Method as claimed in one of the claims 1 to 5,
wherein a control system is provided which controls the transportation steps pulse-wise and coordinates the cooling phases cyclically, whereby particularly the movement cycles of the removal device (11) of the transfer gripper (12) and the after-cooling unit (19) are preferably adjustable independent of one another.
7. Method as claimed in claim 6,
wherein the transfer unit takes over the injection moulds from the removal device (11) in
a horizontal position with the help of the air nozzles (40) or centering mandrels, swivels
these into a vertical position and push them into the water cooled(200)of the
after-cooling unit (19).

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8. Method as claimed in claim 6 or 7,
wherein during handing over of the injection mould (10) from the removal device (11), me air nozzles (40) atop in apuahed-in position for several seconds for the sake- of an intensive blow-cooling, particularly by the hemispherical base (10*) of the inner side of the injection moulds (10).
9. Method as claimed in one of the claims 5 to 8,
wherein the pressure conditions on both sides of the injection mould bases (10') can be independently controlled, so mat in a coordinated manner a blown air current and/or an underpressure condition is generated, and accordingly the injection moulds are retained by underpressure on the one or the other side, or can be ejected by the one or the other direction by means of pressure impact
10. Method as claimed in one of the claims 5 to 9,
wherein the air nozzles (40) are designed as suck-and-blow mandrels, with suction openings for the region of the open end of the injection moulds, in such a way, that various operation conditions can be set in a controlled manner, e.g. a dominant air blowing beam in the region of the closed floor end (10*) in the inner part of the injection moulds (10), or a strong vacuum efiect within the injection mould (10) or a mixed form between both
11. Method as claimed in claim 1,
wherein the transfer gripper (12) and the removal device (11) are conceived for taking up an equal number of injection moulds (10), like the injection mould tool (8,9), whereby the after-cooling unit (19) has water-cooled sleeves (200) arranged in two or multiple rows or even staggered if necessary, ao that by corresponding transverse displacement and longitudinal displacement, the after-cooling unit (19) can take up two or several charges of injection moulds (10), for each injection mould cycle for reduction of the mould cycle time and increasing the after-cooling time.

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12. Method as claimed in one of the claims 1 to 11
wherein the phase of removal of the injection moulds (10) from the mould halves (8,9) and the complete handover to the after-cooling unit (19) is approximate to the time duration of moulding cycle and the total after-cooling time conforms to at least two or three times the moulding cycle time, and a double cooling can be undertaken from inside and outside on the injection moulds (10) during a significant part of fee moulding cycle time directly after removal of the injection moulds (10).
13. Method as claimed in one of the claims 1 to 12.
wherein at least the ejection of the injection moulds (10) takes place supported by air pressure on the air side, and water cooling is supplemented at the end of the injection mould removal as well as at the beginning of after-cooling by means of air blowing nozzles (40) which can be mechanically shifted into the inner side of the injection moulds (10).
14. Injection moulding machine for production of sleeve-shaped injection moulds
(10) closed on one side with a base (1'), consisting of a lock-up mechanism and opening
mechanism, removal and after-cooling units (11,19), in which at least, corresponding to
the number of injection moulds (10) produced per cycle, there are water cooling pipes
(22,30,200) foreseen for the injection moulds (10)> whereby the push-in side for the
injection moulds (10) are arranged lying opposite and a pressure and underpressure-
chamber (27) is arranged connected with the cooling pipe take-up chamber for the
injection moulds (10),
wherein they have a transfer gripper (12), corresponding to the number of injection moulds (10) to be cooled, air nozzles (40) for an inner cooling of the injection moulds (10), through which the injection moulds (10) can be handed over from the removal device (11) into the after-cooling unit (19).

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15. Injection moulding machine as claimed in claim 14,
' wherein the air nozzles (40) are designed pushable into the inner portion of the respective injection moulds (10), whereby an opening of the air nozzles at the blowing mandrel tip can be positioned to almost on the base (10') of me injection moulds (10).
16. Injection moulding machine as claimed in claims 14 to 15,
wherein the air nozzles (40) or blowing mandrels are arranged on aholder plate (15) and form as transfer gripper (12) an independently controllable component, whereby on the transfer gripper (12) fee blowing mandrels (14) are designed as centering mandrels, for taking over fee injection moulds (10) from the removal device (11) in a horizontal position and swiveiing it to a vertical position and subsequently pushing it into the water cooling pipes (200) of the after-cooling unit (19).
17. Injection moulding machine as claimed in claims 14 to 16,
wherein it has a water-cooled removal device (11) and a transfer gripper (12) with an air cooling agent, as well as a water-cooled after-cooling unit (19) and a control unit (St.), through which the movement steps can be controlled pulse-wiEe and me cooling phases can be coordinated cyclically, in such a manner, that from the removal of the injection moulds (10) upto the ejection at me end of the after-cooling phase at least on? cooling can be activated without interruption.
18. Injection moulding machine as claimed in claims 14 to 17,
wherein the after-cooling unit (19) can be shifted like a slide in a horizontal level from a exact take-over position above the transfer unit into an ejection position by means of a transportation belt (20) for taking up or ejection of the injection moulds (10) longitudinally and/or transversely.

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19. Injection moulding machine as claimed in claim 17,
wherein foe transfer gripper (12) mid the removal device (11) can be equipped for taking up can equal number of injection moulds (10), like the injection moulding tool (8,9), and the after-cooling unit (19) has two or several rows of water-cooled sleeves (200) arranged parallely or staggered if required, so that by means of corresponding longitudinal andfor transverse shifting, the after-cooling device (19) can take up two or more charges of injection moulds (10) for each injection moulding cycle for reduction of the moulding cycle time and increasing the cooling time.
20. Injection moulding machine as claimed in claim 14,
wherein at least one mechanically shiftable element for optimizing the air effect on each injection mould (10) is foreseen, whereby the shiftable elements are designed as valve pins (204), especially piston elements (103)* for economic ensuring of clear overpressure or underpressure conditions, in such a way, that the injection moulds (10) drawn by them into the cooling pipes (22,30,200) can be safely ejected on application of overpressure in the pressure chamber (27), and on switching to underpressure in the pressure chamber (27), an underpressure can be generated in a passage channel between pressure chamber and inner space of me cooling pipes (22,30,200), for suctioning the injection moulds (10).
21. Injection moulding machine as claimed in claim 14 or 15,
wherein the water cooling pipes (22,30,200) on the side of the pressure chamber (27) have crowned base portions (207), suitable for corresponding hemispherical bases (10s) of the injection moulds (10), whereby the shiftable element is integrated in the form of a valve pin (204) in the crowned base portion (207).
The aim of the invention is to improve the cooling or subsequent cooling range during the production of pre—shaped bodies for PET bottles, so—called preforms. Water cooling is primarily used for initial cooling and also during subsequent coaling. The air action, however, is improved by assigning mechanically displaceable elements to the air side action. As a result, the security with regard to malfunctions during handling as well as the cooling action can be improved. When combined, two especially advantageous embodiments yield an optimal solution. A valve-like element is provided for ejecting and an air nozzle 40 is provided for the interiorof the reforms, said nozzle assisting in the handling and cooling.

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Patent Number

208213

Indian Patent Application Number

IN/PCT/2001/00442/KOL

PG Journal Number

29/2007

Publication Date

20-Jul-2007

Grant Date

19-Jul-2007

Date of Filing

19-Apr-2001

Name of Patentee

NETSTAL-MASHINEN AG,

Applicant Address

CH-8752, NAFELS, SWITZERLAND.

Inventors:

#	Inventor's Name	Inventor's Address
1	VIRON ALAN	1 CHEMIN DE BARDILLY, DESMONTS, F-45390 PUISEAUX
2	MEIER ERNST	GLARNISCHSTRASSE 6, CH-8868 OBERURNEN,
3	WEINMANN ROBERT, AUTISWEG	AUTISWEG 6, CH - 8872 WEESEN
4	EGGER CASPAR	SCHILTSTRASSE 38 CH-8750 GLARUS

PCT International Classification Number

B29C45/72,35/16

PCT International Application Number

PCT/CH99/00501

PCT International Filing date

1999-10-22

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	198 48837.8	1998-10-22	Germany