Title of Invention | "METHOD FOR THE AUTOMATIC REMOVAL OF INJECTION MOULDED PARTS AND REMOVAL DEVICE FOR INJECTION MOULDED PARTS" |
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Abstract | The invention relates to a method and a removal device for the automatic removal of injection moulded parts from the half moulds (10, 11) of injection moulding machines By installing additional vacuum storage element (61) in consumer proximity, the necessary vacuum is available for each removal in an additional area, independent from pressure variations in the vacuum system Before the beginning of each removal, the available system is monitored by sensor means (70, 71, 72) and by maintaining a vacuum-limit value a movement authorisation is transmitted to the removal robot (30) A pressure switch threshold value is also determined for the vacuum which is adjusted in close proximity to the suction cup during the removal of the injection moulded parts (1) by the suction cups (44) of the removal robot (30). If the pressure switch threshold value is reached as a result of sufficient closeness of the injection moulding parts (1) to the suction caps (44), the removal robot (30) is authorised, by means of a machine control, to carry out additional movements The pressure switch threshold value can be set as a percentage of the start vacuum at the beginning of each removal and as result, the time and removal safety for each part or production charge are optimised |
Full Text | The invention pertains to a method for automatic removal of injection molding parts, especially from disc-shaped injection molding parts from the open mold parts with the help of a removal robot (detachment robot) and at a suction cup vacuum system, further a removal equipment for injection molding parts, especially for the detachment of disc-shaped injection molding parts as optical disc from the mold parts with the help of control medium and a detaching robot with suction cup, which are suitable for connection to a vacuum system. State of the art technic The class (sort) of the injection-molding machine for the production of flat data carriers, has optical disc, displays two mold parts. The one moveable (mobile), first mold parts moved with the help of a drive system as opposed to a drive carrier plate for the form closing (locking) as well as the mold opening. A whole spray cycle comprises the actual injection molding and stamp as well as the removal of the disc-shaped parts with the help of robots. Towards making evident (clear) the basic problem of the removal 2 of the product reference is taken to the figures 9a to 9d, which represent an old loosening (detachment) action of the state of the art technic. in the foreground there stands the removal of the disc-shaped injection molding part between both the opened mold parts, of the mobile mold parts 3 and of the mobile mold parts 4 as well as the delivery of the injection molding part According to figure 9d there follows the discharge of the discshaped injection molding part downwards The figure 9c shows the separate removal of the feed head 2 through a delivery channel. The figure 9a represents the situation according to the closed-off injection and stamping (embossing) process. A moveable stamp 6 has the injection molding part penetrated and thereby the central lock, example given, of a CD (compact disc), is fabricated. The punched middle part with the feed head (sprue) 2 is pounded on the figure 9a leftwards in a matrix shaped sleeve and is held by a piston 8. The figure 9b shows as the next step the withdrawal of the movement of piston 8 with the feed head 2 held with them therein. The stamp 6 is afready retracted again in the counter direction, fully beyond the injection molding part 1 Within the piston 8 is a discharge pin 9, which after complete withdrawal of the piston 8 ejects and throws the feed head with mechanical force, as it is represented in the figure 9c This solution is, so far as the feed head is concerned, very advantageous In the traditional state of the art technic the CDs are removed with the help of robot and suction cups from the opened molds and are handed over with highest possible speed of 3 the further processing, in the practice there various problems can occur In case of the taking over (acceptance) of a fabricated CD by the suctorial discs is not possible that prevalent disturbances occur, for example, through defective application of the CD at the suctorial discs, what can cause (engender) an interruption of the production system. For the acceleration of the robot arms and the duration of time of the total removal process limits are set, when, for example, by too short vacuum inadequate adhesive strength are effective The mentioned problem points hold good also for the feed head (sprue), so far as this is detached in the same manner with a suctorial disc. When in the state of the art technic the safety of the detachment with a fixed threshold value was evaluated as too high, this would lead often to safety disconnection, which in many cases would not be necessary at all. The invention was placed to the task to develop a method and a detaching equipment, which permits a short removal time, utmost possible without disturbances, with a very high operational safety but also without unnecessary safety disconnections with the help of removal robot and suctorial discs. 4 Representation of the Invention The method in accordance with the invention, is distinguished thereby, that for the injection molding parts - removal on the ground of momentary available system vacuum a pressure switch - threshold value or a pressure switch profile for the vacuum adjusting itself in suctorial disc proximity during the taking over (acceptance) of the injection molding parts with the help of the removing robots is determined. The removing equipment in accordance with the invention, is distinguished thereby, that the vacuum system in the proximity of consumer especially in the production system integrates at least a vacuum accumulator and vacuum tank and displays vacuum sensor medium and the medium of control, whereby the movements of the removing robot are noticeable by the vacuum sensor medium and the control medium controllable and/or are monitorable. Larger clarifications in respect of suctonaf disc removal of the state of the art technic have resulted, that a central source of disturbance is the vacuum system Repeated tests in the laboratory could not bring any treatment, since in one laboratory mostly optimum and first of all a constant conditions are given The laboratory vacuum producer is attached in the proximity of the machine. The supply main is therefore short and normally large enough dimensioned. In the customer practice the vacuum 5 producer as against that is often wide away and has many outlets The vacuum supply line is sometimes too small in the cross section When other consumer connected at the vacuum system, for example, somehow reduces the under-pressure,, it is possible in case of in-conducive conditions the relations between suction cups and the injection molding part are impaired in such a manner, that the acceptance (taking over) by the robot takes place deficiently or not at all It has become known from the inventors, that the extremely high performance capacity of the injection molding machines in case of the quick movement of run off with tact frequencies for a total spraying cycle each in the secondary range four problems are in the central position. Each part function must be implemented with the smallest possible time requirement Here the problem is that of the speed, as far as possible without idle times. The problem of the monitoring of each movement, of the movement of the removal robot as of the movement of the injection molding parts. It must be ensured, that each injection molding part is removed in an orderly manner. The problem of the protection of the machine It must be ensured, that in case of any defective function within the framework of the injection molding part removal each subsequent movement, which could lead to damage, is avoided. 6 Each safety disposition, which, in fact, effectively excludes each possible sequence damages, can in so far as lead to large disadvantages, as much too often, that means, more than necessary, the production is interrupted This signifies, that an optimum machine protection and safety disconnections must be found out The new invention proposes to determine at least one parameter downstream, namely one effective pressure switch threshold value in the vacuum system for the further switching on of the movement of the removing robots In short, the new approach (solution) proposes measure, the instantaneous effective vacuum to determine an optimal switching threshold value and the actual switching function for the next movement only during achievement of the switching threshold value to release An analysis of all the functions has resulted that supported on the effective vacuum relations, each according to the practical situation, two parameters can be in the foreground: Stop each further movement of the machine, so far as an effective risk of damage exists, when in the vacuum system a minimum vacuum is not prevalent. Release of motion for the removing robots and vacuumization of the suction cup, define one of each optimum pressure-switch threshold value Important is there that corresponding to the each momentary effective system vacuum of the pre-determined 7 pressure switch threshold value for the vacuum in the suction cup range at the end of the taking over (acceptance) of the injection molding parts through the suctorial disc through corresponding vacuum sensor medium tested and only the case of observance of the threshold value the further moment of the robot is released. It is important there, that according to the instantaneous effective system vacuum of the pre-determined pressure switch threshold value for the vacuum in the suction range at the end of the taking over of the injection molding parts through the suction cups through corresponding vacuum sensor medium tested and only during observance (retention) of the threshold value the further movement of the robot is released. The new approach (solution) offers fully surprising advantages in respect to all for the time being known disturbance possibilities. By the two staged control of the vacuum behaviour afl the disturbances can be excluded (ruled out) so far from the vacuum system that no machine standstills and/or damages of machine occur. Very important is the aspect of the clean mechanical taking over rather delivery of the injection molding parts from the mold at the detaching robot It is immediately determined through the vacuum relations, when the injection molding part does not detach itself from the mold, that the part lies closely but defectively at the suctorial discs, when, for example, the suction apparatus have become deficient as a result of the wear and tear at the lips. With the pressure switch threshold value the time 8 interval from the approximation of the suctorial discs to the injection molding parts upto the complete adhesion at the suctorial discs through the vacuum control is determined in suctorial disc. If the time interval lasts too long, then a defective function must be closed. An object of the new solution is a possible-most steep vacuum ramp, since thereby the acceptance of the injection molding parts takes place in the shortest possible time. The removal of the injection molding part can be optimized with the new approach (solution) both in respect of the speed as well as in respect of the functional certainty optimized. The new invention proposes, before beginning of the removal movements the instantaneously possessable vacuum to determine and in case of adequate system vacuum as it were in the sense of an object handicap, to release the motion of the robot upto the taking over (acceptance) of the injection molding parts and only during achievement of the pressure switch threshold value during complete taking over of the injection molding parts by the suctorial disc the actual removal of the parts are to be implemented. During the removing procedure the holding of the parts are to be continuously checked in accordance with the arrangement. The first practice tests have shown, that upto 200'000 casting cycles no disturbance for the partial removal occur. This as against an extreme case of the state of the art technic, at which par 1 '000 shots 1 to 2 disturbances, occurs. 9 The new solution permits a full number of especially advantageous developments. It is, therefore, reference to be taken to the patent claims 2 to 10 as well as 12 to 19 The new method proposes a small additional - vacuum store (accumulator) in the proximity of the consumer. The additional vacuum - accumulator has the big advantage, that for the short phase of the injection molding part acceptance (take over) by the suction cups and the immediately connecting discharge movement of the robot a corresponding large vacuum store (accumulator) is in possession at the site (place of work). The acceptance (taking over) takes place under definite conditions, independent of present swinging system vacuum relations. The new solution permits, a working storage with connection of all lines and valves machine-sided in the sense of optimized structural groups to the customers as part of the machine to be delivered along with Thereby there causes vacuum-oscillations in a relatively large range no disturbances more in respect of the product detachment (removal) from the mold part. From the collaboration of the described parameters, namely of a vacuum limit value, of the respective determination and control of a pressure switch threshold value in suction cup proximity as well as of the putting in readiness of a suburb-vacuum storage the parts with the largest possible safety and despite in the shortest possible time can be removed. Preferably the removing rotor displays suction cups for the discshaped parts (disc-suction cups), especially for optical discs, as 10 well as at least one feed head suctorial disc, whereby all suctorial discs are connected with the vacuum tank for the purpose of the taking over. Advantageous is there, when the disc suction cups as well as the feed head - suction cup are connected through each separated lines with the vacuum tank through controllable valves. Already the first attempts with the new solution have shown, that a part of the success secret in the arrangement of a steep vacuum-ramp during the critical phase of the taking over (acceptance) of the discs by the suction cups for the ratio under pressure over the time in the effective range of the suction cups lies. The separated lines permit, both for the disc- shaped part as well as for the feed head to arrange the best conditions. It would be also conceivable, to switch on the vacuum tank for the phase through controllable valves only for the phase of the removal of the product in the sense of additional vacuum storage, in each case, so that only for this critical time two sources of vacuum come in (to) action. At the least according to the momentary state it is sufficient when one or two vacuum tanks remain connected as far as possible near to the consumption positions at the vacuum system continuously and thereby with the momentary in the system prevailing under pressure are admitted (impacted). The arrangement of separated lines with each one controllable valves permit an intended time-wise start for both the suction and removal functions, for the optical disc as well as for the feed head (sprue). The both can be shifted in the range of mili seconds, so that a preference can be given to a part. 11 The requirements for the optical discs and for the feed head are basically different in two points. The feed head is waste, so that damage is irrelevant. The feed gate is smaller and in case of necessity difficult to remove The optical disc is in respect of mechanical damage very delicate, can however be removed without difficulty from the molds. In case of necessity it is advantageous to remove the feed head purely mechanically. A very important point in respect of the new solution lies therein, that the pressure distribution is detected at least in the phase of the removal towards monitoring of the actually taken place of the acceptance of the casting part through the suction cups. Before beginning of the take over phase of the injection molding parts the suction cups are connected with the vacuum system, so that the suction cups can such air from the open space. The best point of time for that is shortly before the removal rotor there comes in between the open mold parts Before the proximation of the injection mold part and suction cup the effective vacuum before the suction cup is extremely small, since air is sucked from the open. During the suction of the injection molding parts there closes the gap between the suction cup and the injection molding part, and the effective vacuum builds itself almost in sudden bursts. At the end of this process there lays injection-molding part completely at the suction cup. The result is, that the vacuum effective on the injection molding part in the suction cup which approximates from the system pressure possibly to maximum extent, without reaching this completely According to the new solution also the profile of the vacuum ramp be determined 12 measuring technically and can be compared with a predetermined pressure switch profile. In case of deviations it is possible through corresponding should -/actual monitoring function, for example, a safety switch off for the mold closure are liberated. For the phase of the injection molding parts acceptance and departure three states of affair are possible: 1. The system vacuum is through the duration of time of the removal constant and adequate. 2. The system vacuum swings during the removal strongly. Here the suburb ensures "accumulator" (recorded) vacuum of the automatic removal. The removal can take place suddenly and safely. 3. The system vacuum breaks down on some ground or other during the removal procedure. With the continuous monitored vacuum limit value can be removal function be stopped in the mili second range and machine damages be avoided. The vacuum tank has a double function. On the one hand it offers a vacuum intermediate storage and supports the vacuum effect. Secondly, the vacuum tank offers for the extremely short time span of the injection molding part removal (detachment) such a large Reserve, that a simultaneous vacuum reduction in the vacuum system lets the removal function through a large range almost uninfluenced. 13 In case of applications, in which an optimal vacuum system is already available, one can ignore an additional vacuum tank In this case, however, according to the new solution a pressure monitoring is compulsonly required The new solution permits either, the required operation-safety by an additional vacuum tank, an additional pressure monitoring of both to be provided. The disc suction cups are attached at an acceptance (taking over) head of the removing robot somehow circular-shaped and are together through an own vacuum-connection-line as well as a governable valve connectable direct with the additional vacuum tank. Within the circle shaped attached disc-suction cup is at least one feed head (sprue) suction cup attached, which similarly is joinable through a controllable valve with the additional vacuum tank. Advantageously for the new solution of the vacuum tank and the valve groups as independent, machine sided attached structural components developed, with a connection line to the vacuum system. It is obvious, that all function-essential parts, from vacuum tank upto the suctorial disc, can be optimally dimensioned and thereby a structural standardization for the injection molding part removal follows The connection line can for the total duration of the removal both for the additional vacuum tank as well as from the connection lines to the suction cups remain constantly open. According to the removal taken place of the injection molding parts and swing-out of the robot arms upto a further distribution point the vacuum must be ensured at the suction cup. For the distribution of the injection molding parts these must be detached from the suction cups. For 14 the disc-shaped injection molding parts in the vacuum connecting line between the governable valve and the disc suction cups a further controllable intet or intake valve for the ambient air are attached for the release of the discs with the help of the force of gravity. Because of the small dimensions of the feed head and of the worse suction cup effect in the vacuum connecting line between the controllable valve and the feed head suction cup a controllable valve for the blowing off of the feed head is attached. Here there takes place the release with the compressed air impact. For a stabilization of the pressure ratios it is further possible, in each connecting line for the suction cup a throttle valve has to be provided. The new solution displays a controlling equipment, through which for each cycle the individual blast and suction cycles coordinated and optimized with the mold opening and the mold closure are controllable. Further the pressure sensor medium displays towards monitoring of the pressure ratios in suction cup proximity, especially during the removal and/or of the stress distribution in the additional vacuum tank. The controlling equipment displays programme parts, through which each detachment process either pressure switch - threshold value or pressure switch profile is monitored, in such a manner, that in case of disturbances, according to the nature of the disturbance, an alarm is released and through indicating medium 15 shown and, for example, in case of fhe remaining hanging of a injection molding part in the mold parts the mold closure is immediately stopped. According to the uptil now made attempts the additional vacuum tank should display at least 5 dm3, preferably around 10 dm3 to 50 dm3 equipped capacity. It is especially preferably attached in elements of the machine bed of the injection-mofding machine. All vacuum consumers in the range of the forms and of the detachment are connected to the additional vacuum tank. It is moreover possible, to provide two or more additional tanks, which can be switched on individually or parallelly Short description of the Invention The new solution is now elucidated with the help of some of the examples of execution with further details. It show: the Figure 1 the whole range of form with opened mold halves, the Figure 2 the coming-in movement of the robot arms in the opened form; the Figure 3 the discharge movement of the robot arms with the injection molding parts, the Figure 4 the basic circuit diagram for the core components of the new solution, the Figure 5 a robot construction group; the Figure 6a a section B-B of the figure 6b; the Figure 6b . a view to the suction cup of the robot detaching head; 16 the Figure 6c a view according to the arrowhead D of the figure 6a; the Figure 6d a view according to the arrowhead E of the figure 6a; the Figure 7 a sketch for the new solution with the vacuum tank; the Figure 8a the pressure distribution curve in case of the injection molding parts detachment with a vacuum supply without storage (vacuum tank); the Figure 8b the pressure distribution curve with storage and vacuum tank; the Figure 8c a segment enlargement of the figure 8a; the Figure 8d a segment enlargement of the figure 8b; the Figure 9a to 9d various phases of the injection molding parts detachment with the help of a solution of the state of the art technic. Methods and execution of the Invention The figure 1 shows a section through the two opened form sides of an injection-molding machine (form) for the fabrication of compact disc. On the right photo side the fixed mold part 10, on the left photo side mobile mold parts 11. An injection head is indicated symbolically with double arrowheads 12. The flat injection molding part 1 is still in the mold. Impact helps, as air or mechanical helps, are not represented. The feed head 2 is 17 already separated from the fiat injection molding part 1 and prevails still in the feed head channel Each of both the mold sides displays a baste plate 13 and 14, a first supporting plate 15 and 16 as well as a mold plate 17 respectively 18. Within the form (mold) plates 17 respectively a8 is a tamper 18 each 19 is inserted in With the arrowheads 20 is the stamping movement and the construction of the stamping force of the moveable mold parts 11 indicated. The injection and stamping procedure is pre-supposed as known. The figure 2 shows the beginning of the insertion movement of the robot arms 31 of the removal robot 30 with a taking over head (acceptance) 32 in the highest position. Both the mold parts 10 and 11 are in opened condition corresponding with the figure no.l. The figure 3 shows the departure movement of the robot arm 31, whereby the taking-over-head (acceptance) 32 holds a compact disc. The figure 4 shows schematically an overview on a specially advantageous development of the new solution (approach) with a vacuum system 60 as well as with an additional vacuum tank 61. On the vacuum system no further discussion is made. The air is simplified through a large cross sectional vacuum pipeline 62 in a vacuum pump 63 sucked on and through an extractor socket 64 blown off at the free air Schematically the vacuum pipeline 62 is 18 connected through a fragment 62' on the one hand directly with the vacuum tank 61 and on the other hand through connecting pipelines 21, 22 with the place of consumption. At each of the connecting pipelines 21 and 22 a controlled valve 66 and 67 is attached, where the control of all the valves through the machine calculator (comptometer) 49 takes place through corresponding control lines. The last fragrant of the vacuum connection at the disc suction cup 44 as well as the feed head suctorial disc 50 is produced through vacuum pipeline pieces 45 and 46, Both in both the vacuum pipeline pieces 45 and 46 as well as at the vacuum tank 61 a vacuum sensors 70, 71, 72 in each case, is attached, which are connected to the control lines 73, 74, 75 similarly with the machine calculator 49 (comptometer). The object of the superior control is beside the guarantee of all launching and safety function also an economic operation. The vacuum is switched-on only for the time period, during which the requirement exists, which takes place with the control of the valves 66, 67, 68 (fig 7). In the figure 5 a total robot structure group 40 is represented, where on the right side in the photo of the removing robot 30 with robot arm 31 as well as taking-over-head 32 is represented. The taking-over-head 32 is supported at a rotary axis 41, so that this beside the swinging movement around a drive axis 42 also around the axis 43 of the rotary axis 41 is moveable. At the taking-overhead 32 some recognizable suctorial disc 44 and a vacuum pipeline piece 45, 46 each for the connection of the suctorial disc 19 with the vacuum systems are attached. The robot structural group 40 displays a drive motor and servomotor 47 as well as a gear unit 48. The control of all movements of the taking-over-head 32 takes place through a machine calculator 49. The figure 6b is a view D of the figure 6a and the figure 6a a segment B-B of the figure 6b. Six disc-suctorial discs 44 are attached circular-shaped at the taking-over-head 32. In the center of the 6 disc-suctorial discs 44 there is a feed head suctorial disc 50. The feed head suctorial discs 44 are together at the vacuum pipeline piece 45 and the individual feed head suctorial disc 50 is connected ai the vacuum-piping piece 46. The figures 6c and 6deach show the front and reverse side of the acceptance (taking-over-head) 32. The figure 7 shows schematically the most important components of the new solution corresponding with the figure 4. With a dash-dotted square the components are bordered (framed-in), which comprise a machine sided structural components 76. The frame 77 comprises a valve structural component, which is attached similarly at the machine side. As against that there belongs to the vacuum pump 63 as a rule not directly to an injection-molding machine, but represent the vacuum system with the pipelines 62. The figure 7 shows one each specific development The feed head is spat off through controlled switching-on of the blowing air through the compressed air valve 95, as it were, through an air blast impact around the suctorial disc The disc is, as again0st that, led through a changing over of the valve 66 and abandoned to 20 the flowing-in of surrounding air in the vacuum terminal clamp 45. The valve gives for this purpose the feed head opening 79 free (release). In both vacuum terminal clamps 45, 46 throttle 78 each is attached. Thereby it is possible to achieve, that from the beginning of the feed head function directly after opening of the vacuum connection through valve 66, 67 the vacuum connecting terminal clamp 45, 46 have a relatively small vacuum. Thereby the starting conditions for the control technical governance optimum. The vacuum ram is thereby much higher, and almost double high as without throttle. A central function of the new solution (approach) is clarified with the figures 8a to 8d with the help of each of a solution with and without vacuum store. There enter in the field, as is represented in the following, more than desired removal problems, which mostly adhere with an inadequate vacuum supply. The possible cause is, for example, the minimum prescribed vacuum of 750 mbar, which on ground of the inadequate performance capacity of the vacuum pump or because of the larger leaks is not achieved. The connection pipelines are too long and possess an inadequate cross section. Since the vacuum installation is basically a thing of the customer and not of the machine manufacturer, in this regard only limited influence (action) can be taken. The vacuum requirement is in the cycle course subject to relatively large oscillations. Especially at the point of time of the feed head of disc and the feed head there follows "a consumption peak". It was investigated, how far a vacuum storage this equip "vacuum peak" and thereby the removal problems in the field can render 21 safe. Attempt-wise for this purpose a storage (store) with 10 liters content was attached at the machine and connected through a closeable, short hose-connection with the vacuum valves. Various consumption positions are connected at a compressed air system. It deals there with about three mechanical functions: discharging pin in front and back, perforator in front and back as well rejecter in front and behind. For the air blast the three most important consumers (customer) are: - blowing air movement side - blowing air for the nozzle side - feed-head blow off Each of the mentioned functions is controlled by the machine calculator (comptometer) through a control valve in the required tact (cycle). The compressed air system is supplied with by a central compressed air supply. The compressed air supply is as a rule the less critical part. Important is the complete coordination of the vacuum as well as the air blast functions, which must be optimized in the range of the milliseconds. The figure 8a shows the ratio without additional vacuum tank and storage (store). During switching on of "vacuum disc" and "vacuum feed-head" there break the vacuum in the system around almost 250 mbar. After disc and feed head are sucked off, there builds this breaking-in again and achieves within around 300 ms again a stationary condition. The figure 8b shows the same outline, however, with an additional suburb vacuum storage. 22 The figure 8b shows the same outline however, with an additional suburb-vacuum-store. The pressure break-in during switch-on of the valve is hardly more determinable. The tracing after the suction of disc and feed-head has distinctly become steeper and effect there with a reduction of the removing time of average 40 ms. On the other hand the disc and feed head during returning of the Z-strokes and during start of the discharge movement with around 15% higher force retained. For the combination of optimum dynamic with good accessibility and simple operation a solution with pressure sensor is proposed. Such sensors offer a relatively highly dissolving (dissipating) analogous signal, which in the control can be determined and evaluated. The feed (control) shaft determined, in each case, can be directly indicated at the projection screen. Not at last, there results with a sensor-solution advantages in comparison to the decentralize intelligence. Through the assembly of a consumer proximity arranged vacuum-suburb-store it is possible especially in case of deficient vacuum supply the removal of more sure and the removal time are distinctly reduced with the higher dynamic in the vacuum formation there raises the holding strength of disc and feed head during return journey of the Z-stroke and in case of the removal movement. With vacuum sensor arranged in the consumer proximity for disc and dead head (sprue) the corresponding sensor signals can be passed on almost with some time to a controller and the order required in each case can be immediately granted. 23 In both the figures 8a and 8b the withdrawal was started with a vacuum of 800 mbar. The effective vacuum for the disc as well as for the feed head lies shortly before beginning of the removal without the store (figure 8a) at about above 400 mbar, with additional store (figure 8b) at above 500 mbar. The vacuum ramp VR1 without storage as essentially flater and with less effective vacuum in comparison with vacuum ramps VR2 with store (figure 8b). As result thereof the discharge movement (Z-stroke) with store is around double so quick as without store (figure 8a) can take place. In the figures 8c and 8d the critical range of both solutions (with and without store) is represented in enlarged measure once more, whereby 8c of the figure 8a and 8d of the figure 8b corresponds with. There follows from the comparison, that without store the pressure in the system at start-vacuum 1 of 800 mbar on around 550 mbar at start delivery at the beginning of the suction process of the injection molding part fall. The corresponding values with store lies at start-vacuum 2 = 800 mbar, start-delivery (surrender) = 770 mbar. Similarly striking is the comparison of both the vacuum ramps with and without vacuum rather store. In order to guarantee the functional safety, in both the cases somehow a same ramp height was selected, without store VRA1 (vacuum ramp feed head), (VRD1 vacuum ramp disc), with store VRA2 (vacuum ramp feed head), VRD2 (Vacuum ramp disc). The basic difference lies in the effective vacuum height at the end of the suction of the injection mold part: without store at around above 600 mbar and with store above 700 mbar. For the second in the 24 time requirement without store at around 100 msec, with store at around 30 to 50 msec. It signifies DS1-V of the bottom threshold value (without store) and Dsi-0 of the pressure switch threshold value (without store), further DS2-U of the bottom threshold valve with store and DS2- of the pressure switch threshold value with store. The advantages of the new solutions with additional vacuum tank are thereby evident. Besides the aspects of the operation safety there follows simultaneously also a shortening of the withdrawal time, as it were in the sense of safer, quicker and better. In the figure 8d as example each one pressure switch threshold value each for the disc is drawn-in for the feed head. The ratios for the disc and for the feed head are in several respects very different, not lastly also through the geometrical measurements. The new solution permits this aspect to be taken into account and the both especially to control and monitor. In case of the registered example there lies the system vacuum in the point of time start withdrawal at 800 mbar and therewith through a required vacuum limit value of 750 mbar. The calculator 49 calculates during the beginning of the removal of the pressure switch threshold value for the disc with around 725 mbar as well as for the feed-gate with around 750 mbar. The robot arm 31 travels towards release through the vacuum limit value testing (checking-in) in between opened forms and the taking-over-head proximate itself to the injection molding parts. With Disc-U as well as the Disc2-U is the beginning of the proximating injection molding parts and suctorial discs is marked. The quick reduction of 25 the column between injection molding part and suction cup has the result, that the vacuum builds itself quickly in sudden bursts, in which the suction cup inner space and the vacuum pipeline pieces 45, 46 are "empty sucked" through the vacuum effect. The empty-suction can be shortened by the optimal dimensioning of the vacuum pipeline pieces. After less than 50 msec both for the feed head as well as for the disc the pressure switch threshold value is attained. With the corresponding switching signal the release for the swing out of the removing rotor is given. The pressure switch threshold value is determined by each removal cycle. In many cases it can be enough, when a fixed value is assumed. The fixed value adjusts itself primarily according to the momentary vacuum in the system and in the vacuum storage 61. The big advantage of the new solution lies therein, that the pressure switch threshold value of each specific situation can be fitted. In case of unproblematic injection molding parts the vacuum pump can be reduced. In case of very particular (exacting) injection molding parts the safety can be raised thereby, that the pressure switch threshold value as far as possible near to the start-vacuum before the removal cycle assumed and thereby a somehow longer removal time to put up with. The solution according to the invention is fully specially suitable, to optimize the running experience in the sense of a learning (capable) programme the momentary calculation of the pressure switch threshold value for each specific operating contract. It is possible to determine any value from, for example, 1 % - 30% of the agreement start vacuum. Therewith the new invention the task 26 placed very good, in which a safety disconnection and a safety stop only in case of actual, menacing danger of damages exist. The pressure switch threshold value be pre-determined in various ways. It can, for example, as fixed value prescription-like in the electronic memory of the calculator, taken off, and in respect of bandwidth of the start vacuum be determined. It is also possible, that the customer from time to time a percentual value of 3 to 30% at the machine terminal be brought-in. Further it is also possible that corresponding vacuum pumps e.g. through turn control signal auto (pilot) be advanced. Further it is also possible that corresponding vacuum pumps e.g. through turn control signal (auto pilot) of bandwidths be advanced and accordingly the switching function for the further movement of the removing rotor are liberated. The big advantage of the new solution lies therein, that at an enough Start-Vacuum of each individual removal cycle in respect of time, safety and economy is optimizable, through a corresponding controlled guide of the removing robots. The new solution proposes a clear, lower limit of the lower vacuum limit. The vacuum must display at least the corresponding value e.g., 750 mbar for the release order of the removal cycle. Both for the disc as well as for the feed head a pressure switch threshold value and therewith the bottom limit for the range of the release of the further movement of the removing robots are determined. There the vacuum actual-value before begin can be multiplied with a factor K1 respectively K2 (for disc respectively feed head) be determined. The movement release takes place only when for both of the pressure switch threshold value is achieved. The 27 pressure switch threshold value is only the bottom limit of the permitted range removal. The object is there: for the taking-over (acceptance) a high but not unnecessarily high effective vacuum to be ensured, the switching point should still lie in tank in steep ramp part and however maximum most proximity at the vacuum. By making available of a suburb-vacuum-store are the vacuum oscillations of the system dampened. As simplest method the pressure switch threshold value as percentage value, for example, 70% to 97% of the current vacuum, in each case, selected in the suburb-vacuum-store. Patent Claims 1. Process to withdraw automatically injection molded parts, specially to withdraw disc-type of injection molded parts from open form-halves by means of withdrawal robots and suction bowls connected to a vacuum system, characterized by that for the withdrawal of injection molded parts based on available system vacuum pressure switch threshold value or a pressure switch profile for the adjusting vacuum of the injection molded parts determined by the withdrawal robot. 2. Process as per claim 1, characterized by that for decision of the continuation of movement shortly before and/or during the drive of the withdrawal robot the pressure switch threshold value is checked. 3. Process as per claim 1 or 2, characterized by that the pressure switch threshold value above vacuum sensor in the region of the suction bowls for every withdrawal cycle checked and the decontrol of the further movement of the withdrawal robot only by reaching the pressure switch threshold value or the pressure switch profile. 4. Process as per one of the claims 1 to 3, characterized by that to generate a steep vacuum ramp for the phase of taking over the injection molded parts through the suction bowls or during the approach of the injection molded parts to the suction bowls a vacuum storage in proximity of users is connected. 5. Process as per one of the claims 1 to 4, characterized by that the pressure switch threshold value or the pressure switch profile because of the momentary under pressure in the vacuum tank during each injection molded parts removal is adapted continuously. 6. Process as per one of the claims 1 to 5, characterized by that before each withdrawal cycle because of pressure sensor values the system pressure is determined and the withdrawal motion of the withdrawal robot begins only on reaching a vacuum limiting value in the vacuum system and is completed by reaching the pressure switch threshold value or pressure switch profile. 7. Process as per claim 6, characterized by that the pressure switch threshold value or a pressure switch profile is calculated or determined on the basis of pressure prevailing momentarily in the vacuum tank. The pressure switch threshold value is set ca. 3% - 30% above the pressure limiting value, preferably 5% - 20% under the prevailing pressure in the vacuum tank by beginning of the withdrawal cycle. 30 8 Process as per one of the claims 1 to 7, characterized that the withdrawal of the injection molded parts, specially the discshaped parts and of the casting, from machine calculator through start or calculation as well as check of the pressure switch threshold value is individually done and controlled. 9. Process as per one of the claims 1 to 8, characterized by that the suction bowls of the withdrawal robot for the disc shaped parts (disc suction bowls) display at least one casting suction bowl where by all the suction bowls are connected with the vacuum storage for withdrawal. 10. Process as per one of the claims 1 to 9, characterized by that the vacuum connection for the disc suction bowls as well as cast suction bowl through each of the separated cables are made or controlled with vacuum storage over separate valves. 11. Process as per one of the claims 1 to 10, characterized by that the release of the discs by the weight of surrounding air fed into the vacuum line. 12. Withdrawal equipment for injection molding parts, specially for the withdrawal of disc shaped injection molding parts, e g. optical discs from the form halves by means of control equipment 31 and a withdrawal robot with suction bowls, which can be connected to a vacuum system characterized by that the vacuum system lies in users' proximity, specially integrated in the production system or vacuum tank and displays vacuum sensor, where by the movements of the withdrawal robot over the vacuum sensor medium and the control medium can be regulated and controlled. 13. Withdrawal equipment as per claim 12, characterized by that the take-over head of the withdrawal robot is arranged to disc suction bowls over a vacuum conduit and a regulating valve as well as a connecting conduit with which the vacuum tank can be connected. 14. Withdrawal equipment as per claim 12 or 13, characterized by that the circularly arranged disc suction bowls over a vacuum conduit piece and a valve that can be regulated as well as a connecting conduit with which the vacuum tank can be connected. 15. Withdrawal equipment as per claims 12 to 14, characterized by that the vacuum tank with the connecting conduits as well as the users with switching valves and vacuum sensorik formed as integrated construction groups of the machine with a connecting conduit to a vacuum source. 32 16. Withdrawal equipment as per one of the claims 12 to 15, characterized by that in the vacuum conductor piece between the regulating vacuum valve and the casting suction bowl an additional regulating valve is arranged for the blowing off of the casting with compressed air, 17. Withdrawal equipment as per one of the claims 12 to 16, characterized by that the vacuum conductor pieces from the valves to the suction bowls in the cross-section optimized such that by open suction bowls the flow is limited and in case of closed suction bowls the maximum possible vacuum can be generated quickly. 18. Withdrawal equipment as one of the claims 12 to 17, characterized by that it displays a control equipment over which the individual blow and suction cycles coordinated with the form open and the form closed as well as the motions of the withdrawal robot are regulated. 19. Withdrawal equipment as per one of the claims 12 to 18, characterized by that the vacuum sensor medium displays for the control of the vacuum relations for the withdrawal phase in the suction bowl area, specially in the vacuum conductor piece as well as in the vacuum tank. 33 20. Withdrawal equipment as per one of the claims 12 to 19, characterized by that a vacuum tank displays a volume of at least 5 dm3, specially approximately 10 dm3 upto 50 dm3, whereby preferably arranged one or two vacuum tanks in the carrying structure of the injection molding machine. 34 9. After complete return of the piston 8, the casting is hit and expelled with mechanical force as represented in figure 9c. This solution is very advantageous as far as the casting is concerned. In the traditional technical stand the CD's are removed by means of robots and suction bowls from the open forms and are handed over for further processing with the greatest possible speed. In practice, different problems may arise thereby: - By take over of a finished CD through the suction bowl unforeseen troubles may arise, e.g. by defective laying of the CD on the suction bowls may cause a break in production. - For the acceleration of the robot arm or the duration of the full withdrawal is limited when e.g. due to low vacuum insufficient friction-forces are working. - The mentioned problem-points are valid for the casting as far as they are taken from a suction bowl. When in the technical stand the security of the withdrawal with a fixed threshold value is valued too high, it led often to safety switching offs, which in many cases were not at all necessary. The invention has set the task to develop a process and a removal equipment, which not only allows a high degree of operational safety but also without unnecessary safety switching off by means of take-off robots and suction bowls. Representation of the invention The process as per invention is characterized by that the removal of the injection molding on the basis of the available system vacuum a pressure switch threshold value or a pressure-switch 35 profile for that in the vicinity of the suction bowl assigned vacuum by the take-over of the casting parts determined by the pressure-switch threshold value or the pressure-switch profile on the basis of the continuously adapted momentary under-pressure during each casting part removal. The removal equipment as per invention is characterized by that the vacuum system in users' proximity, specially integrated in the production system, displays at least one vacuum storage or vacuum tank and vacuum sensor medium, whereby the suction bowls are connectable to the vacuum tank over a regulating value and the motions of the removing robot are watchable over a vacuum sensor medium whereby, by means of a regulating medium a pressure switch threshold value or a pressure switch profile is adaptable during each injection casting removal on the basis of prevailing under-pressure. [AMENDED PAGE] |
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00348-kolnp-2005-correspondence-1.1.pdf
00348-kolnp-2005-correspondence-1.2.pdf
00348-kolnp-2005-correspondence-1.3.pdf
00348-kolnp-2005-correspondence.pdf
00348-kolnp-2005-description(complete).pdf
00348-kolnp-2005-international publication.pdf
00348-kolnp-2005-international search authority report.pdf
00348-kolnp-2005-others document.pdf
00348-kolnp-2005-pct others.pdf
00348-kolnp-2005-pct request.pdf
00348-kolnp-2005-priority document other.pdf
00348-kolnp-2005-priority document.pdf
348-kolnp-2005-granted-abstract.pdf
348-kolnp-2005-granted-claims.pdf
348-kolnp-2005-granted-correspondence.pdf
348-kolnp-2005-granted-description (complete).pdf
348-kolnp-2005-granted-drawings.pdf
348-kolnp-2005-granted-examination report.pdf
348-kolnp-2005-granted-form 1.pdf
348-kolnp-2005-granted-form 18.pdf
348-kolnp-2005-granted-form 2.pdf
348-kolnp-2005-granted-form 26.pdf
348-kolnp-2005-granted-form 3.pdf
348-kolnp-2005-granted-form 5.pdf
348-kolnp-2005-granted-letter patent.pdf
348-kolnp-2005-granted-priority document.pdf
348-kolnp-2005-granted-reply to examination report.pdf
348-kolnp-2005-granted-specification.pdf
348-kolnp-2005-granted-translated copy of priority document.pdf
Patent Number | 219350 | ||||||||
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Indian Patent Application Number | 348/KOLNP/2005 | ||||||||
PG Journal Number | 18/2008 | ||||||||
Publication Date | 02-May-2008 | ||||||||
Grant Date | 30-Apr-2008 | ||||||||
Date of Filing | 07-Mar-2005 | ||||||||
Name of Patentee | NETSTAL-MASCHINEN AG. | ||||||||
Applicant Address | INDUSTRIESTRASSE,CH-8752 NAFELS | ||||||||
Inventors:
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PCT International Classification Number | B25J 15/06 | ||||||||
PCT International Application Number | PCT/CH2003/000602 | ||||||||
PCT International Filing date | 2003-09-05 | ||||||||
PCT Conventions:
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