Title of Invention	METHOD AND APPARATUS FOR THE MEANUFACTURE OF BRUSHES AND BRUSHES MANUFACTURED BY THE SAME.
Abstract	A method for the manufacture of brushes with a plastic bristle carrier and a bristle configuration of individual or bundlewise-combined plastic bristles is proposed, in that the fastening-side ends of the bristles or bundles are melted to a thickening, thickenings of adjacent bristles or bundles are interconnected by aftershaping and displacement of the plastics material and the connections are subsequently embedded in the plastics material of the bristle carrier. The thickenings are shaped by means of a mould to a clearly defined support structure of webs connecting adjacent thickenings and subsequently the support structure and the bristles projecting over the same are embedded by a short length in the plastics material of the bristle carrier. An apparatus for performing such a method and a brush manufactured by such a method are also proposed.

Title of Invention

METHOD AND APPARATUS FOR THE MEANUFACTURE OF BRUSHES AND BRUSHES MANUFACTURED BY THE SAME.

Abstract

A method for the manufacture of brushes with a plastic bristle carrier and a bristle configuration of individual or bundlewise-combined plastic bristles is proposed, in that the fastening-side ends of the bristles or bundles are melted to a thickening, thickenings of adjacent bristles or bundles are interconnected by aftershaping and displacement of the plastics material and the connections are subsequently embedded in the plastics material of the bristle carrier. The thickenings are shaped by means of a mould to a clearly defined support structure of webs connecting adjacent thickenings and subsequently the support structure and the bristles projecting over the same are embedded by a short length in the plastics material of the bristle carrier. An apparatus for performing such a method and a brush manufactured by such a method are also proposed.

Full Text	METHOD AND APPARATUS FOR THE MANUFACTURE OF BRUSHES AND BRUSHES MANUFACTURED BY THE SAME The invention relates to a method for the manufacture of brushes with a plastic bristle carrier and a bristle configuration, fastened thereto and comprising individual or bundlewise-combined plastic bristles, in that the fastening-side ends of the bristles or bundles are melted to a thickening, thickenings of adjacent bundles are interconnected by aftershaping and displacement of the plastic mass and the connections are subsequently embedded in the plastics material of the bristle carrier. The invention is also directed at an apparatus for performing the method and to brushes manufactured according to the method. The special features and problems described hereinafter using the example of toothbrushes apply equally to numerous hygiene brushes, as well as various other brushes for different uses. However, the prior art in connection with' toothbrushes is the furthest advanced and consequently special reference is made thereto. Modern dental medicine requires toothbrushes with a sensitive bristle action, the bristle configuration being adaptable to the greatest possible extent to the cleaning faces (teeth and interdental gaps) and massaging faces (gingiva), so as on the one hand to not only follow the spherical tooth surfaces on cleaning, but also to cover the desired interdental gaps and simultaneously avoiding injury during the desired massaging of the gingiva. The requirement of reaching with the bristles the areas of the oral cavity to be cleaned and massaged on the one hand requires a certain length of the bristles, whilst on the other the complete overall height (bristle length plus 2 overall height of the brush head) is to be kept low, so as to ensure an optimum bristle action even in the confined circumstances of the oral cavity. As exclusively the bristles decisive for the cleaning and massaging action and the bristle carrier makes no contribution thereto, the aim is to keep the overall height of the bristle carrier as small as possible. A limit is placed on this in that the bristles must have an adequate embedding length in order to offer the necessary resistance to pulling out oral extraction. Bristles or even bristle bundles which are released from the bristle configuration not only have an unpleasant effect in the oral cavity, but can even lead to health hazards in the gastrointestinal tract if swallowed. The in part opposing requirements for high extraction resistance and low overall height can only be fulfilled with difficulty. At present brushware and in particular toothbrushes is still preponderantly made using conventional punching technology, i.e. the bundles are looped and fastened by anchoring in prepared bristle carrier holes. This procedure requires a bristle carrier overall height of at least 4 to 6 mm. Toothbrushes produced by punching technology are only able to inadequately fulfil modern hygiene demands due to the existing gaps in the vicinity of the bristle fastening and the resulting inclusion of dirt and bacteria. Substantially hygienically satisfactory toothbrushes can be produced by moulding processes or thermoplastic joining processes, to which the method according to the preamble of claim 1 relates. The fastening-side ends of the bristles are then provided with thickenings with which they are either pressed or shaped into the soft plastic mass of the bristle carrier or are placed in an injection mould, in which the bristle carrier molten mass is injection moulded 3 around the thickenings. This makes it possible to attain overall bristle carrier heights of 3.0 to 4.5 mm. The limit is determined here again by the bristle embedding length offering the necessary extraction resistance. The requirement for a limited overall bristle carrier height is more particularly in conflict with the requirements of an adequate extraction resistance if account has to be taken of the further requirement in modern dentistry for a flexible behaviour of the bristle configuration. This presupposes a corresponding flexibility of the bristle carrier and consequently a specific plastic choice and/or design measures. Through the flexibilizing of the bristle carrier the extraction resistance of the bristles is reduced, because the bristles are no longer held in a rigid environment. This more particularly applies if wholly or partly rubber-like materials, such as elastomers are used for the bristle carrier. Purely constructional measures an the bristle carrier e.g. consist of a dividing up of the bristle carrier into areas in joint-like form (EP 577 656, WO 92/17092). However, this generally leads to an increase in the overall height. The same applies in the case of toothbrushes in which the flexibilizing of the bristle configuration is achieved by means of elastomeric areas of the bristle carrier (WO 97/07707, WO 97/24048, WO 97/25899, WO 97/25900). Attempts have already been made to resiliently mount the bristles in the bristle carrier (DE 195 38 569 Al) or to provide the bristle carrier with an elastomeric material and to weld the bristles to said material (DE 36 28 722 Al, DE 195 30 057 Al). It is also known (WO 97/20484) to form the bristle carrier from a supporting skeleton of a relatively rigid plastic and fill the skeleton with an elastomer, the bristles being embedded in the skeleton material 4 or in the elastomer. Here again no overall height reduction is obtained and the flexibility of the bristle configuration is restricted to the elastomeric marginal areas. It is also known (DE 197 43 556 Al) to subsequently separate the injection moulded skeleton and then fill the same with elastomer. In the case of rigid bristle carriers it is known (EP 405 204 Bl, DE 197 38 256 Al) to introduce the bristle bundles into bores in a holding plate and melt same onto the back of the holding plate, whilst shaping the melt into corresponding depressions of the bores, so that all the bundles are connected at the back by means of a type of plate. This plate is then covered by the correspondingly recessed bristle carrier or it forms the bristle carrier together with the rigid holding plate. This construction in no way satisfies modern requirements regarding the flexibility of toothbrushes. With toothbrushes having thermoplastically inserted or injection moulded in bristle bundles with thickenings at the fastening-side end it is known (EP 150 785 Bl, EP 759 711 Bl) to aftershape the thickenings an each bundle in order to widen same in plate-like manner and consequently increase the shear strength in the bristle carrier under the action of extraction forces, or also to shape the thickenings of adjacent bundles to form a cohesive thickening (EP 197 384 Bl, EP 326 634 Al), exclusively strength aspects being in the foreground. The problem of the invention is to propose a method for the manufacture of brushes which, in the case of an adequate bristle extraction resistance, allows a reduction of the overall height of the brush head. According to a further development a substantially controllable resilience of the 5 bristle configuration is to be made possible. According to the invention this problem is solved in that the thickenings are shaped by a mould to a clearly defined support structure of webs connecting adjacent thickenings and then the support structure and the bristles projecting over the same are embedded over a short length in the plastics material of the bristle carrier. In the method according to the invention use is made of the plastics mass melted at the fastening-side end of the bristles or bundles in order to obtain a clearly defined support structure between the thickenings of the bundles or bristles introducing the tensile forces acting on the bristle bundles into the complete bristle carrier. It is no longer solely the shear strength of the bristle carrier material in the area of the thickenings which is decisive for the extraction resistance of the individual or bundlewise combined bristles, but larger areas of the bristle carrier significantly contribute thereto. If required, this makes it possible to reduce to a significant extent the bristle embedding length and in any case the overall height of the bristle carrier. Also in the case of highly flexible or rubber-like plastics for the bristle carrier limited embedding lengths can be implemented. Whereas with brushes with embedded bristles manufactured according to known methods it was possible to achieve an extraction resistance in the case of individual, vertical bristles of up to 150 g and in the case of bundles up to 800 g, as a result of the inventive method the extraction resistance of the individual bristles can be increased to above 500 g and for bundles to above 2000 g. The hitherto minimum possible embedding length of 0.5 mm can be reduced to 0.25 mm, i.e. by half. 6 The support structure necessary for the desired extraction resistance can be produced independently of the spacing of the bundles or individual bristles within the bristle configuration and also independently of the bundle diameter, which was not possible up to now with the known methods. According to a preferred development, between the thickenings and the webs connecting them are formed plastic-free recesses, which during the moulding or injection moulding of the bristle carrier or during the thermoplastic joining process allow a complete flow round of the support structure and consequently ensure a firm anchoring of the bristle configuration. According to a preferred variant of the method the thickenings are supported on their bristle side and the plastics mass displaced from the thickenings during shaping for forming the support structure is controlled against the support by the closing pressure of the mould. Due to the shaping contour of the mould and the control of the flow pressure the plastics mass displaced from the thickenings can be distributed in planned manner with respect to the desired support structure and the desired cross-sections can be implemented in the webs of the support structure. Another preferred variant of the method according to the invention is characterized in that the plastics mass displaced during shaping from the thickenings for the formation of the support structure is controlled by the bristle length melted in the thickenings. This method is particularly advantageous if the bristle configuration comprises bundles having a differing cross- 7 section, individual, vertical bristles and bristles with different spacings. These inequalities are compensated by the melting of a varying bristle length, in that the mass available for displacement is controlled. In the method according to the invention it is possible to proceed in such a way that following the initial melting of the fastening-side ends of the bristles or bundles, the thickenings are shaped with a time lag in a still plastic state to the connections. The shaping forces are relatively low in this method. Instead it is possible to proceed in such a way that following the initial melting of the fastening-side ends of the bristles or bundles, the thickenings are shaped with a time lag in the still ductile state to the connections. In this method variant only a narrow or confined union is produced in the area of the thickenings and optionally a positive engagement. However, the necessary increase in the extraction resistance can still be obtained in this way. The method according to the invention is particularly suitable for the manufacture of toothbrushes or hygiene brushes, where a highly flexible bristle configuration is desired. In such a case the procedure is such that for obtaining a predetermined flexibility of the bristle configuration, the moment of inertia of the bristle carrier in the bending axis of the bristle configuration and the plastics material of the bristle carrier are so selected with respect to the modulus of elasticity thereof that the flexibility of the bristle carrier alone is greater than the predetermined flexibility of the bristle configuration, and that the number of connections of individual bristles and/or bundles and their moment of inertia acting in the bending axis in conjunction with the moment of inertia of 8 the thickenings can at least locally be selected in such a way that the flexibility of the bristle carrier is damped to the predetermined amount for the bristle configuration. As has been intimated hereinbefore, the inventive method is based an a prior art such as is e.g. described in EP 197 384 Bl and EP 336 634 Al. Unlike in this prior art, which does not involve itself further with the elasticity of the bristle configuration, in the inventive method a flexibility (elasticity) is given to the bristle carrier which is greater than that required for the particular need. This flexibility is obtained by the choice of the material, which can e.g. be a highly elastic thermoplastic material, an elastomer or the like and is predetermined in that the bristle carrier is given a correspondingly low moment of inertia with respect to the bending axis, which generally coincides with the longitudinal axis of the toothbrush. In such a bristle carrier having a correspondingly low moment of inertia with respect to the bending axis and/or undergoes a pronounced shape change during use, it is not possible to guarantee the necessary extraction resistance. The method according to the invention deals with this problem in that the connections of individual bristles and/or bundles obtained through the shaping of the thickenings have their number and their moment of inertia acting in the bending axis, whilst taking account of the moment of inertia of the thickenings, designed in such a way that the greater flexibility of the bristle carrier is damped, so as in this way to give the bristle configuration the predetermined flexibility. These method measures need only be locally provided on the bristle head in order to produce clearly defined bending areas in and transversely to the longitudinal axis of the bristle head. As the connections are essentially only intended to contribute to an increase in the shear strength and it is consequently mainly a question of the plane of shear and the volume available for shearing, the thickenings can be shaped in the vicinity of the webs to a cross-section, whose effective moment of inertia is lower than that of the thickenings wherein the plastic material is displaced from the thickenings. This measure is aided in that the bristles generally are made from a higher grade plastic than the bristle carrier and consequently the thickenings and webs or grids have better strength characteristics. It is also possible for part of the webs, with respect to the moment of interia, to be shaped to such an extent that they act as joints. In such areas preponderantly, if not exclusively, the higher flexibility of the bristle carrier has its effect, so that zonally there is a greater flexibility on the bristle configuration. In a variant of the method according to the invention a support structure covering all the thickenings is preshaped from webs connecting adjacent thickenings, is applied to and connected with the thickenings and subsequently the support structure and the bristles are embedded over a short length in the plastics material of the bristle carrier. This variant is particularly advantageous for large brushes, where vital significance is not attached to the overall height of the bristle carrier. It is also advantageous if for strength reasons, a different plastic is used for the support structure than the bristle material or also if a different material, e.g. a textile or wire mesh to be penetrated by the plastic of the thickenings is to be used. It is also possible to combine both methods, in that part of the support structure is produced by the displacement of.... 10 plastics material from the thickenings and the missing part is either subsequently e.g. moulded or injection moulded on using a thermal process or connected as a preshaped part to the existing support structure. The invention also relates to an apparatus for performing the method. Such an apparatus has a mounting support receiving the bristles and/or the bundles of the entire bristle configuration of the brush in channels, a device for supplying the bristles and/or bundles in the channels to a position in which their fastening-side ends project over the mouth of the channels. Such an apparatus also has a device for melting the fastening-side ends and a shaping device for aftershaping the melted ends. Such apparatuses form part of the prior art in conjunction with the known methods described. According to the invention, such an apparatus is characterized in that the shaping device has a male die associated with each thickening for the lateral displacement of the plastics material of the thickenings and at least one shaping unit placed between the male dies and the closing unit for shaping the displaced plastic material to the connections between the thickenings. Preferably said shaping device has at least one closing unit for forming plastic-free spaces between the male dies, projecting with respect to said male dies and which can be placed an the mounting support. The male dies have a shaping surface, whose outline at least corresponds to the outline of the thickening at the fastening-side ends of the bristles. With the same the thickenings are shaped and in particular pressed flat, so that the plastics material is displaced in the area between the bristles or bundles, accompanied by the formation of the support structure. between the male dies is located the 11 closing unit, which is placed directly on the mounting support in order to limit the lateral spread of the displaced material, whilst the shaping unit covering the areas between the male dies and the closing unit brings about the shaping of the webs. Preferably, at least the closing unit is in advance compared with the male dies and the shaping unit, so that initially those areas of the support structure into which the displaced material is not to penetrate are blocked off. In this embodiment the male dies and shaping unit can be constructed in one piece. It can alternatively be advantageous to resiliently support the shaping unit, so that in the case of a possibly fluctuating displaced material a compensation occurs. A separate control of the shaping unit and the male dies can also be advantageous. According to an embodiment the shaping face of the shaping unit, at least in predetermined areas, can spring back with respect to the shaping faces of the male dies, so that in the area of the connections, the plastics material is located in a plane set back in the bristle carrier and consequently in the pressure zone during the deflection of the bristle carrier. Instead of this the shaping face of the shaping unit can project with respect to the shaping face of the male dies, so that the connections are more strongly displaced into the tension zone of the bristle carrier. The male dies, closing unit and shaping unit can be constructed as a one-stage mould, so that the entire bristle configuration can be constructed in a single working stroke with this mould. The mounting support with the channels receiving the bristles and/or bundles advantageously simultaneously serves as an abutment for the mould. 12 The shaping device can additionally at least zonally be provided with a heating device in order to assist the flow of the displaced plastics material or in order to temper the plastic of the support structure. According to a preferred development, the mounting support with the channels receiving the bristles and/or bundles simultaneously serves as part of a mould, particularly an injection mould for the bristle carrier, so that it shapes the bristle carrier on filling the mould on the side of the bristle configuration. Thus, the mounting support simultaneously serves for the positioning of the bristles or bundles in accordance with the configuration thereof in the bristle configuration and for the formation of the thickenings and support structure for the bristles or bundles and finally as a moulding during the manufacture of the bristle carrier. For this purpose the bristles and/or bundles are displace-able in the direction of the thickenings in the mounting support and the thickenings can be adjusted in the mould to the desired embedding depth in the bristle carrier, said embedding depth being of a minimum nature as a result of the inventive measures, so as to bring about a minimum overall height at the bristle carrier, but still ensuring an adequate extraction resistance of the bristles. The invention also relates to a brush manufactured according to the abovedescribed method and which, as is known per se, comprises a plastic bristle carrier and a bristle configuration of individual or bundlewise-combined plastic bristles, which are provided at their fastening-side ends with melted on thickenings by means of which they are embedded in the bristle carrier. According to the invention. 13 such a brush is characterized in that the bristles and/or bundles of the entire bristle configuration by means of webs connecting the thickenings from the plastic of the bristles forming a support structure increasing the extraction resistance. The support structure can at least zonally have a smaller thickness than that of the thickenings and can optionally be so thin that zonally joints are formed, which in particular aid a zonal flexibility of the bristle carrier. The extraction resistance and also the flexibility of the bristle carrier can also be influenced in that the webs are at least zonally located in a different plane to the thickenings. If the webs are e.g. located in the neutral bending axis, they are least stressed by centrifugal forces, whereas they act as a damping member when located in the pressure or tension zone. The invention is described in greater detail hereinafter relative to embodiments and the attached drawings, wherein show: Fig. 1 A detail of a brush. Fig. 2 A plan view of the bristle configuration according to fig. 1, without bristle carrier. Fig. 3 A detail of a brush with individual, vertical bristles. Fig. 4 A plan view of the bristle configuration of the brush according to fig. 3, without the bristle carrier. 14 Fig. 5 A detail of another embodiment of a brush with individual bristles. Fig. 6 A plan view of the bristle configuration without bristle carrier of the embodiment of fig. 5. Fig. 7 A larger scale section through the head of a toothbrush. Fig. 8 A larger scale detail of the section of fig. 6. Fig. 9 A section corresponding to fig. 7 in a plane between adjacent bundles. Fig. 10 A larger scale detail of the section of fig. 9. Fig. 11 A plan view of the bristle configuration of the toothbrush of figs. 7 and 9. Fig. 12 A section through a mounting support for the bundles in a first manufacturing stage. Fig. 13 A section through a mould in a second manufacturing stage. Fig. 14 A section XIV-XIV according to fig. 13. Fig. 15 A section XV-XV according to fig. 14. Fig. 16 A section XVI-XVI according to fig. 14. Fig. 17 A view of the back of the support structure of the bristle configuration manufactured in accor- 15 dance with figs. 12 to 16. Fig. 18 A representation of the mounting support corresponding to fig. 12 in a method variant. Fig. 19 The mounting support with part of the mould in a further method stage. Fig. 20 A section with the mould closed in the bundle plane. Fig. 21 A section of the closed mould in a plane between the bundles. The embodiments of brushes shown in figs. 1 to 11 are manufactured in accordance with the method of the invention. The brush according to fig. 1 comprises a plastic bristle carrier 1 and bristles 2 combined to bundles 3 and which are melted to thickenings 4 at their fastening-side ends. By means of said thickenings 4 the bundles 3 are embedded, e.g. injection moulded into the bristle carrier 1, or are inserted in a thermoplastic process. The thickenings 4 of the bundles 3 are connected by means of a clearly defined support structure 5, which in the represented embodiment comprises webs 6 connecting neighbouring thickenings 4 and plastic-free recesses 7 located between the same. In the embodiments according to figs. 3 to 6 individual, vertical bristles 2 are provided at their fastening-side ends with thickenings 4 by melting the bristle ends and shaped by the displacement of plastics material from the thickenings 4 to a plate-like support structure 8, the individual bristles 2 being combined into groups. In the embodiment according to fig. 5 the individual bristles 2 are mutually displaced, e.g. in the form of circular groups and 16 once again thickenings 4 are shaped to a support structure 9 with recesses 10. Figs. 7 to 10 show the head 11 of a toothbrush with bundles 12, 13 having different shapes at the use-side end and which are also of different lengths. The fastening-side ends of said bundles are once again melted to form thickenings 4 and are interconnected by means of webs 6 through the displacement of the plastics material and which consequently form a support structure for the entire bristle configuration of bundles 12 and 13. The support structure and a short length of the bundles 12, 13 are once again embedded in the bristle carrier 1 of the brush head 11. The webs 6 between the thickenings can, as shown in figs. 8 and 10, be kept very thin and then form a type of joint between the individual bundles 12, 13, but still contribute to increasing the extraction resistance of the bundles 12, 13. Figs. 12 to 16 show an apparatus for performing the method or for the manufacture of the brushes according to figs. 1 to 11. Fig. 12 shows a mounting support 15, where the bundles 16 forming a bristle configuration and which optionally have different diameters, are placed in channels 17. The bundles 16 are introduced by means of a not shown supply device into the channels 17 of the mounting support 15 and are appropriately fixed there in correspondingly narrow cross-sections of the channels 17 or the like by clips, plugs, etc. The supply takes place in such a way that the fastening-side ends 18 of the bundles 16 project over the mounting support 15. These fastening-side ends 18 are then melted in known manner, so that thickenings 19 are formed from the molten mass. A shaping device 14 (figs. 13 and 14) then comes into action and comprises individual male dies 21 associated with the thickenings and a closing unit formed from individual dies 22, which project over the male 17 dies 21 and are placed directly on the surface of the mounting support 15 between the thickenings 19. The male dies 21 also act against the thickenings 19 and displace the still soft plastic, but at least ductile plastics material to the side and said material is prevented from flowing further by the dies 22. In the area between the male dies 21 and the closing dies 22 can be provided further male dies 24 or a complete shaping unit 25, which displaces the plastics material to a clearly defined support structure, as shown in fig. 17 in a view of the rear of the support structure. It comprises thickenings 19, the thinner webs 26 connecting the same and the intermediate recesses 27. The control during the displacement of the plastics material from the thickenings 19 takes place through the shaping contour of the shaping device 14 in conjunction with the closing pressure of the mould 20 against the mounting support 15. A further control possibility is illustrated in figs. 19 to 21. Here the bristle configuration comprises bundles 28 and 29 having a different cross-section. With the fastening-side end 30 or 31 thereof they are introduced to a differing extent into the channel 17 of the mounting support 15. The bristles are in each case melted to the length projecting over the mounting support 15, so that taking account of the spacings between the bundles 28, 29 sufficient plastics material is made available to bridge the spacings through a uniform thickness support structure 34. The mould 20 once again comprises male dies 21 and closing dies 22. The male dies 21 once again displace the material from the thickenings 32, 33 in all the mould cavities with the exception of the areas blocked off by the closing dies 22. This makes it possible to produce the support structure 34 shown in figs. 20 and 21 with an approximately constant cross-section despite the different cross 18 sections of the bundles 28, 29 and different spacings be tween the same. 19 CLAIMS 1. Method for the manufacture of brushes with a plastic bristle carrier and a bristle configuration of individual or bundlewise-combined plastic bristles fastened thereto, in that the fastening-side ends of the bristles or bundles are melted to a thickening, thickenings of adjacent bristles or bundles are interconnected by subsequent shaping and displacement of plastics material and the connections are subsequently embedded in the plastics material of the bristle carrier, characterized in that the thickenings {4, 19, 32, 33) are shaped by means of a mould. (20) to a clearly defined support structure (5, 9, 34) of webs (6, 26) connecting adjacent thickenings (4, 19, 32, 33) and then the support structure (5, 9, 34) and the bristles (2) projecting over the same are embedded in the plastics materials of the bristle carrier (1). 2. Method as claimed in claim 1, wherein that plastic-free recesses (7, 10, 27) are formed between the thickenings (4, 19, 32, 33) and the webs (6, 26) connecting them. 3. Method as claimed in claim 1 or 2, wherein that the thickenings (4, 19, 32, 33) are supported on their bristle side and the plastics material displaced from the thickenings (4, 19, 32, 33) during shaping for forming the support structure {5, 9, 34) is controlled by the closing pressure of the mould (20) against the support. 4. Method as claimed in one of the claims 1 to 3, wherein in that the plastics material displaced from 20 the thickenings (4, 19, 32, 33) during shaping for forming the support structure (5, 9, 34) is controlled by the length of the bristles (2) melted to the thickenings (4, 19, 32, 33). 5. Method as claimed in one of the claims 1 to 4, wherein that the thickenings (4, 19, 32, 33) of more than two bristles (2) or bundles (3, 12, 13, 16, 28, 29) are shaped to a grid connecting them. 6. Method as claimed in one of the claims 1 to 5, wherein that following the initial melting of the fastening-side ends (18, 30, 31) of the bristles (2) or bundles (3, 12, 13, 16, 28, 29), the thickenings (4, 19, 32, 33) are shaped with a time lag and in a still plastic state to the connections. 7. Method as claimed in one of the claims 1 to 5, wherein that after the initial melting of the fas tening-side ends (18, 30, 31) of the bristles (2) or bundles (3, 12, 13, 16, 28, 29), the thickenings (4, 19, 32, 33) are shaped to the connections with a time lag and in a still ductile state. 8. Method as claimed in one of the claims 1 to 7 for the manufacture of toothbrushes or hygiene brushes, wherein that for obtaining a predetermined flexibil ity of the bristle configuration the moment of inertia of the bristle carrier (1) in the bending axis of the bristle configuration and the plastic of the bristle carrier (1) are so selected with respect to the modulus of elasticity thereof that the flexibility of the bris tle carrier (1) alone is greater than the predetermined flexibility of the bristle configuration, and that the number of connections of individual bristles (2) and/or 21 bundles (3, 12, 13, 16, 28, 29} and their moment of inertia acting in the bending axis, in conjunction with the moment of inertia of the thickenings (4, 19, 32, 33}, is at least locally selected in such a way that the flexibility of the bristle carrier (1} is damped to the amount predetermined for the bristle configuration. 9. Method as claimed in one of the claims 1 to 8, wherein that the plastics material displaced from the thickenings (4, 19, 32, 33) is shaped in the vicin ity of the webs (6, 26) to a cross-section, whose ef fective moment of inertia is lower than that of the thickenings (4, 19, 32, 33). 10. Method as claimed in one of the claims 1 to 9, wherein that, with respect to their moment of iner tia, part of the webs (6, 26) is shaped to such an ex tent that they act as joints. 11. Method for the manufacture of brushes with a plastic bristle carrier and a bristle configuration of individ ual or bundlewise-combined plastic bristles fastened thereto, in that the fastening-side ends of the bris tles or bundles are melted to a thickening and the thickenings of adjacent bristles or bundles are inter connected and the connections are subsequently embedded in the plastics material of the bristle carrier, char acterized in that a support structure (5, 9, 34), co vering all the thickenings (4, 19, 32, 33), of webs (6, 26) connecting adjacent thickenings (4, 19, 32, 33) is applied to and connected with the latter and that sub sequently the support structure (5, 9-, 34) and the bristles (2) are embedded in the plastics material of the bristle carrier (1). 22 12. Method as claimed in one of the claims 1 to 11, wherein that part of the support structure (5, 9, 34) is manufactured according to the method of one of the claims 1 to 10 and the missing part according to the method of claim 11 is applied to the preshaped sup port structure (5, 9, 34). 13. Method as claimed in claim 11 or 12, wherein in that a subsequently applied support structure (5, 9, 34) is connected by injection moulding to the thicken ings (4, 19, 32, 33) or the preshaped support structure (5, 9, 34) . 14. Apparatus for performing the method as claimed in one of the claims 1 to 10 or 12, with a mounting support re ceiving the bristles and/or bundles of the complete bristle configuration of a toothbrush in channels, a device for supplying the bristles and/or bundles in the channels to a position in which their fastening-side ends project over the mouth of the channels, a device for melting the fastening-side ends and a shaping de vice for the after-shaping of the melted ends, charac terized in that the shaping device (14) has a male die (21) associated with each thickening (4, 19, 32, 33) for the lateral displacement of the plastics material of the thickenings (4, 19, 32, 33) and at least one shaping unit (25) located between the male dies (21) for shaping the displaced plastics material to the con nections between the thickenings (4, 19, 32, 33). 15. Apparatus as claimed in claim 14, wherein that the shaping device (14) has at least one closing unit for forming plastic-free spaces positioned between and projecting with respect to the male dies (21) and which can be placed an the mounting support (15). 23 16. Apparatus as claimed in claim 14 or 15, wherein that at least the closing unit is in advance compared with the male dies (21) and shaping unit (25). 17. Apparatus as claimed in claim 16, wherein that the male dies (21) and shaping unit (25) are con structed in one piece. 18. Apparatus as claimed in one of the claims 14 to 17, wherein that the male dies (21) and shaping unit (25) are separately controllable. 19. Apparatus as claimed in one of the claims 14 to 18, wherein in that at least in predetermined areas, the shaping face of the shaping unit (25) springs back with respect to the shaping faces of the male dies (21) . 20. Apparatus as claimed in claims 14 or 15, wherein in that the closing unit, male dies (21) and shaping unit (25) are constructed as a one-piece mould (20). 21. Apparatus as claimed in one of the claims 14 to 20, wherein that the mounting support (15) with the channel (17) receiving the bristles (2) and/or bundles (3, 12, 13, 16, 28, 29) simultaneously serves as an abutment for the shaping device (14). 22. Apparatus as claimed in one of the claims 14 to 21, wherein that the shaping device (14) is at least zonally provided with a heating device. 23. Apparatus as claimed in one of the claims 14 to 22, wherein that the mounting support (15) with 24 the channels (17) receiving the bristles (2) and/or bundles (3, 12, 13, 16, 28, 29) simultaneously forms part of a mould for the bristle carrier (1) and during the filling of the mould shapes the bristle carrier (1) at the bristle configuration side. 24. Apparatus as claimed in one of the claims 14 to 23, wherein that the bristles (2) and/or bundles (3, 12, 13, 16, 28, 29) in the mounting support (15) are displaceable in the direction of the thickenings (4, 19, 32, 33), which in the mould can be adjusted to the desired embedding depth in the bristle carrier (1). 25. Brush, manufactured as claimed in the method of one of the claims 1 to 13, comprising a plastic bristle car rier and a bristle configuration of individual or bun- dlewise-combined plastic bristles, provided at their fastening-side ends with melted thickenings, by means of which they are embedded in the bristle carrier, characterized in that the bristles (2) and/or bundles (3, 12, 13, 16, 28, 29) of the entire bristle configuration are connected by means of webs of the plastic of the bristles (2) connecting the thickenings (4, 9, 32, 33) and which form a support structure (5, 9, 34) increasing the resistance to extraction of the bristles. 26. Brush as claimed in claim 25,wherein that at least zonally, the support structure (5, 9, 34) has a smaller thickness than the thickenings (4, 19, 32, 33). 27. Brush as claimed in claim 25 or 26, wherein that the webs (6, 26) of the support structure (5, 9, 34) are constructed as joints. 25 28. Brush as claimed in one of the claims 25 to 27, wherein that the webs (6, 26), at least partly, are located in a different plane to the thickenings (4, 19, 32, 33) . A method for the manufacture of brushes with a plastic bristle carrier and a bristle configuration of individual or bundlewise-combined plastic bristles is proposed, in that the fastening-side ends of the bristles or bundles are melted to a thickening, thickenings of adjacent bristles or bundles are interconnected by aftershaping and displacement of the plastics material and the connections are subsequently embedded in the plastics material of the bristle carrier. The thickenings are shaped by means of a mould to a clearly defined support structure of webs connecting adjacent thickenings and subsequently the support structure and the bristles projecting over the same are embedded by a short length in the plastics material of the bristle carrier. An apparatus for performing such a method and a brush manufactured by such a method are also proposed.

Full Text

METHOD AND APPARATUS FOR THE MANUFACTURE OF BRUSHES AND BRUSHES MANUFACTURED BY THE SAME
The invention relates to a method for the manufacture of brushes with a plastic bristle carrier and a bristle configuration, fastened thereto and comprising individual or bundlewise-combined plastic bristles, in that the fastening-side ends of the bristles or bundles are melted to a thickening, thickenings of adjacent bundles are interconnected by aftershaping and displacement of the plastic mass and the connections are subsequently embedded in the plastics material of the bristle carrier. The invention is also directed at an apparatus for performing the method and to brushes manufactured according to the method.
The special features and problems described hereinafter using the example of toothbrushes apply equally to numerous hygiene brushes, as well as various other brushes for different uses. However, the prior art in connection with' toothbrushes is the furthest advanced and consequently special reference is made thereto.
Modern dental medicine requires toothbrushes with a sensitive bristle action, the bristle configuration being adaptable to the greatest possible extent to the cleaning faces (teeth and interdental gaps) and massaging faces (gingiva), so as on the one hand to not only follow the spherical tooth surfaces on cleaning, but also to cover the desired interdental gaps and simultaneously avoiding injury during the desired massaging of the gingiva.
The requirement of reaching with the bristles the areas of the oral cavity to be cleaned and massaged on the one hand requires a certain length of the bristles, whilst on the other the complete overall height (bristle length plus

2
overall height of the brush head) is to be kept low, so as to ensure an optimum bristle action even in the confined circumstances of the oral cavity. As exclusively the bristles decisive for the cleaning and massaging action and the bristle carrier makes no contribution thereto, the aim is to keep the overall height of the bristle carrier as small as possible. A limit is placed on this in that the bristles must have an adequate embedding length in order to offer the necessary resistance to pulling out oral extraction. Bristles or even bristle bundles which are released from the bristle configuration not only have an unpleasant effect in the oral cavity, but can even lead to health hazards in the gastrointestinal tract if swallowed. The in part opposing requirements for high extraction resistance and low overall height can only be fulfilled with difficulty.
At present brushware and in particular toothbrushes is still preponderantly made using conventional punching technology, i.e. the bundles are looped and fastened by anchoring in prepared bristle carrier holes. This procedure requires a bristle carrier overall height of at least 4 to 6 mm. Toothbrushes produced by punching technology are only able to inadequately fulfil modern hygiene demands due to the existing gaps in the vicinity of the bristle fastening and the resulting inclusion of dirt and bacteria.
Substantially hygienically satisfactory toothbrushes can be produced by moulding processes or thermoplastic joining processes, to which the method according to the preamble of claim 1 relates. The fastening-side ends of the bristles are then provided with thickenings with which they are either pressed or shaped into the soft plastic mass of the bristle carrier or are placed in an injection mould, in which the bristle carrier molten mass is injection moulded

3
around the thickenings. This makes it possible to attain overall bristle carrier heights of 3.0 to 4.5 mm. The limit is determined here again by the bristle embedding length offering the necessary extraction resistance. The requirement for a limited overall bristle carrier height is more particularly in conflict with the requirements of an adequate extraction resistance if account has to be taken of the further requirement in modern dentistry for a flexible behaviour of the bristle configuration. This presupposes a corresponding flexibility of the bristle carrier and consequently a specific plastic choice and/or design measures. Through the flexibilizing of the bristle carrier the extraction resistance of the bristles is reduced, because the bristles are no longer held in a rigid environment. This more particularly applies if wholly or partly rubber-like materials, such as elastomers are used for the bristle carrier.
Purely constructional measures an the bristle carrier e.g. consist of a dividing up of the bristle carrier into areas in joint-like form (EP 577 656, WO 92/17092). However, this generally leads to an increase in the overall height. The same applies in the case of toothbrushes in which the flexibilizing of the bristle configuration is achieved by means of elastomeric areas of the bristle carrier (WO 97/07707, WO 97/24048, WO 97/25899, WO 97/25900).
Attempts have already been made to resiliently mount the bristles in the bristle carrier (DE 195 38 569 Al) or to provide the bristle carrier with an elastomeric material and to weld the bristles to said material (DE 36 28 722 Al, DE 195 30 057 Al). It is also known (WO 97/20484) to form the bristle carrier from a supporting skeleton of a relatively rigid plastic and fill the skeleton with an elastomer, the bristles being embedded in the skeleton material

4
or in the elastomer. Here again no overall height reduction is obtained and the flexibility of the bristle configuration is restricted to the elastomeric marginal areas. It is also known (DE 197 43 556 Al) to subsequently separate the injection moulded skeleton and then fill the same with elastomer.
In the case of rigid bristle carriers it is known (EP 405 204 Bl, DE 197 38 256 Al) to introduce the bristle bundles into bores in a holding plate and melt same onto the back of the holding plate, whilst shaping the melt into corresponding depressions of the bores, so that all the bundles are connected at the back by means of a type of plate. This plate is then covered by the correspondingly recessed bristle carrier or it forms the bristle carrier together with the rigid holding plate. This construction in no way satisfies modern requirements regarding the flexibility of toothbrushes.
With toothbrushes having thermoplastically inserted or injection moulded in bristle bundles with thickenings at the fastening-side end it is known (EP 150 785 Bl, EP 759 711 Bl) to aftershape the thickenings an each bundle in order to widen same in plate-like manner and consequently increase the shear strength in the bristle carrier under the action of extraction forces, or also to shape the thickenings of adjacent bundles to form a cohesive thickening (EP 197 384 Bl, EP 326 634 Al), exclusively strength aspects being in the foreground.
The problem of the invention is to propose a method for the manufacture of brushes which, in the case of an adequate bristle extraction resistance, allows a reduction of the overall height of the brush head. According to a further development a substantially controllable resilience of the

5
bristle configuration is to be made possible.
According to the invention this problem is solved in that the thickenings are shaped by a mould to a clearly defined support structure of webs connecting adjacent thickenings and then the support structure and the bristles projecting over the same are embedded over a short length in the plastics material of the bristle carrier.
In the method according to the invention use is made of the plastics mass melted at the fastening-side end of the bristles or bundles in order to obtain a clearly defined support structure between the thickenings of the bundles or bristles introducing the tensile forces acting on the bristle bundles into the complete bristle carrier. It is no longer solely the shear strength of the bristle carrier material in the area of the thickenings which is decisive for the extraction resistance of the individual or bundlewise combined bristles, but larger areas of the bristle carrier significantly contribute thereto. If required, this makes it possible to reduce to a significant extent the bristle embedding length and in any case the overall height of the bristle carrier. Also in the case of highly flexible or rubber-like plastics for the bristle carrier limited embedding lengths can be implemented. Whereas with brushes with embedded bristles manufactured according to known methods it was possible to achieve an extraction resistance in the case of individual, vertical bristles of up to 150 g and in the case of bundles up to 800 g, as a result of the inventive method the extraction resistance of the individual bristles can be increased to above 500 g and for bundles to above 2000 g. The hitherto minimum possible embedding length of 0.5 mm can be reduced to 0.25 mm, i.e. by half.

6
The support structure necessary for the desired extraction resistance can be produced independently of the spacing of the bundles or individual bristles within the bristle configuration and also independently of the bundle diameter, which was not possible up to now with the known methods.
According to a preferred development, between the thickenings and the webs connecting them are formed plastic-free recesses, which during the moulding or injection moulding of the bristle carrier or during the thermoplastic joining process allow a complete flow round of the support structure and consequently ensure a firm anchoring of the bristle configuration.
According to a preferred variant of the method the thickenings are supported on their bristle side and the plastics mass displaced from the thickenings during shaping for forming the support structure is controlled against the support by the closing pressure of the mould.
Due to the shaping contour of the mould and the control of the flow pressure the plastics mass displaced from the thickenings can be distributed in planned manner with respect to the desired support structure and the desired cross-sections can be implemented in the webs of the support structure.
Another preferred variant of the method according to the invention is characterized in that the plastics mass displaced during shaping from the thickenings for the formation of the support structure is controlled by the bristle length melted in the thickenings.
This method is particularly advantageous if the bristle configuration comprises bundles having a differing cross-

7
section, individual, vertical bristles and bristles with different spacings. These inequalities are compensated by the melting of a varying bristle length, in that the mass available for displacement is controlled.
In the method according to the invention it is possible to proceed in such a way that following the initial melting of the fastening-side ends of the bristles or bundles, the thickenings are shaped with a time lag in a still plastic state to the connections. The shaping forces are relatively low in this method.
Instead it is possible to proceed in such a way that following the initial melting of the fastening-side ends of the bristles or bundles, the thickenings are shaped with a time lag in the still ductile state to the connections. In this method variant only a narrow or confined union is produced in the area of the thickenings and optionally a positive engagement. However, the necessary increase in the extraction resistance can still be obtained in this way.
The method according to the invention is particularly suitable for the manufacture of toothbrushes or hygiene brushes, where a highly flexible bristle configuration is desired. In such a case the procedure is such that for obtaining a predetermined flexibility of the bristle configuration, the moment of inertia of the bristle carrier in the bending axis of the bristle configuration and the plastics material of the bristle carrier are so selected with respect to the modulus of elasticity thereof that the flexibility of the bristle carrier alone is greater than the predetermined flexibility of the bristle configuration, and that the number of connections of individual bristles and/or bundles and their moment of inertia acting in the bending axis in conjunction with the moment of inertia of

8
the thickenings can at least locally be selected in such a
way that the flexibility of the bristle carrier is damped
to the predetermined amount for the bristle configuration.
As has been intimated hereinbefore, the inventive method is based an a prior art such as is e.g. described in EP 197 384 Bl and EP 336 634 Al. Unlike in this prior art, which does not involve itself further with the elasticity of the bristle configuration, in the inventive method a flexibility (elasticity) is given to the bristle carrier which is greater than that required for the particular need. This flexibility is obtained by the choice of the material, which can e.g. be a highly elastic thermoplastic material, an elastomer or the like and is predetermined in that the bristle carrier is given a correspondingly low moment of inertia with respect to the bending axis, which generally coincides with the longitudinal axis of the toothbrush. In such a bristle carrier having a correspondingly low moment of inertia with respect to the bending axis and/or undergoes a pronounced shape change during use, it is not possible to guarantee the necessary extraction resistance. The method according to the invention deals with this problem in that the connections of individual bristles and/or bundles obtained through the shaping of the thickenings have their number and their moment of inertia acting in the bending axis, whilst taking account of the moment of inertia of the thickenings, designed in such a way that the greater flexibility of the bristle carrier is damped, so as in this way to give the bristle configuration the predetermined flexibility. These method measures need only be locally provided on the bristle head in order to produce clearly defined bending areas in and transversely to the longitudinal axis of the bristle head.

As the connections are essentially only intended to contribute to an increase in the shear strength and it is consequently mainly a question of the plane of shear and the volume available for shearing, the thickenings can be shaped in the vicinity of the webs to a cross-section, whose effective moment of inertia is lower than that of the thickenings wherein the plastic material is displaced from the thickenings. This measure is aided in that the bristles generally are made from a higher grade plastic than the bristle carrier and consequently the thickenings and webs or grids have better strength characteristics.
It is also possible for part of the webs, with respect to the moment of interia, to be shaped to such an extent that they act as joints. In such areas preponderantly, if not exclusively, the higher flexibility of the bristle carrier has its effect, so that zonally there is a greater flexibility on the bristle configuration.
In a variant of the method according to the invention a support structure covering all the thickenings is preshaped from webs connecting adjacent thickenings, is applied to and connected with the thickenings and subsequently the support structure and the bristles are embedded over a short length in the plastics material of the bristle carrier.
This variant is particularly advantageous for large brushes, where vital significance is not attached to the overall height of the bristle carrier. It is also advantageous if for strength reasons, a different plastic is used for the support structure than the bristle material or also if a different material, e.g. a textile or wire mesh to be penetrated by the plastic of the thickenings is to be used. It is also possible to combine both methods, in that part of the support structure is produced by the displacement of....

10
plastics material from the thickenings and the missing part is either subsequently e.g. moulded or injection moulded on using a thermal process or connected as a preshaped part to the existing support structure.
The invention also relates to an apparatus for performing the method. Such an apparatus has a mounting support receiving the bristles and/or the bundles of the entire bristle configuration of the brush in channels, a device for supplying the bristles and/or bundles in the channels to a position in which their fastening-side ends project over the mouth of the channels. Such an apparatus also has a device for melting the fastening-side ends and a shaping device for aftershaping the melted ends. Such apparatuses form part of the prior art in conjunction with the known methods described. According to the invention, such an apparatus is characterized in that the shaping device has a male die associated with each thickening for the lateral displacement of the plastics material of the thickenings and at least one shaping unit placed between the male dies and the closing unit for shaping the displaced plastic material to the connections between the thickenings.
Preferably said shaping device has at least one closing unit for forming plastic-free spaces between the male dies, projecting with respect to said male dies and which can be placed an the mounting support.
The male dies have a shaping surface, whose outline at least corresponds to the outline of the thickening at the fastening-side ends of the bristles. With the same the thickenings are shaped and in particular pressed flat, so that the plastics material is displaced in the area between the bristles or bundles, accompanied by the formation of the support structure. between the male dies is located the

11
closing unit, which is placed directly on the mounting support in order to limit the lateral spread of the displaced material, whilst the shaping unit covering the areas between the male dies and the closing unit brings about the shaping of the webs.
Preferably, at least the closing unit is in advance compared with the male dies and the shaping unit, so that initially those areas of the support structure into which the displaced material is not to penetrate are blocked off. In this embodiment the male dies and shaping unit can be constructed in one piece. It can alternatively be advantageous to resiliently support the shaping unit, so that in the case of a possibly fluctuating displaced material a compensation occurs. A separate control of the shaping unit and the male dies can also be advantageous.
According to an embodiment the shaping face of the shaping unit, at least in predetermined areas, can spring back with respect to the shaping faces of the male dies, so that in the area of the connections, the plastics material is located in a plane set back in the bristle carrier and consequently in the pressure zone during the deflection of the bristle carrier. Instead of this the shaping face of the shaping unit can project with respect to the shaping face of the male dies, so that the connections are more strongly displaced into the tension zone of the bristle carrier.
The male dies, closing unit and shaping unit can be constructed as a one-stage mould, so that the entire bristle configuration can be constructed in a single working stroke with this mould. The mounting support with the channels receiving the bristles and/or bundles advantageously simultaneously serves as an abutment for the mould.

12
The shaping device can additionally at least zonally be provided with a heating device in order to assist the flow of the displaced plastics material or in order to temper the plastic of the support structure.
According to a preferred development, the mounting support with the channels receiving the bristles and/or bundles simultaneously serves as part of a mould, particularly an injection mould for the bristle carrier, so that it shapes the bristle carrier on filling the mould on the side of the bristle configuration. Thus, the mounting support simultaneously serves for the positioning of the bristles or bundles in accordance with the configuration thereof in the bristle configuration and for the formation of the thickenings and support structure for the bristles or bundles and finally as a moulding during the manufacture of the bristle carrier.
For this purpose the bristles and/or bundles are displace-able in the direction of the thickenings in the mounting support and the thickenings can be adjusted in the mould to the desired embedding depth in the bristle carrier, said embedding depth being of a minimum nature as a result of the inventive measures, so as to bring about a minimum overall height at the bristle carrier, but still ensuring an adequate extraction resistance of the bristles.
The invention also relates to a brush manufactured according to the abovedescribed method and which, as is known per se, comprises a plastic bristle carrier and a bristle configuration of individual or bundlewise-combined plastic bristles, which are provided at their fastening-side ends with melted on thickenings by means of which they are embedded in the bristle carrier. According to the invention.

13
such a brush is characterized in that the bristles and/or bundles of the entire bristle configuration by means of webs connecting the thickenings from the plastic of the bristles forming a support structure increasing the extraction resistance.
The support structure can at least zonally have a smaller thickness than that of the thickenings and can optionally be so thin that zonally joints are formed, which in particular aid a zonal flexibility of the bristle carrier.
The extraction resistance and also the flexibility of the bristle carrier can also be influenced in that the webs are at least zonally located in a different plane to the thickenings. If the webs are e.g. located in the neutral bending axis, they are least stressed by centrifugal forces, whereas they act as a damping member when located in the pressure or tension zone.
The invention is described in greater detail hereinafter relative to embodiments and the attached drawings, wherein show:
Fig. 1 A detail of a brush.
Fig. 2 A plan view of the bristle configuration according to fig. 1, without bristle carrier.
Fig. 3 A detail of a brush with individual, vertical bristles.
Fig. 4 A plan view of the bristle configuration of the brush according to fig. 3, without the bristle carrier.

14
Fig. 5 A detail of another embodiment of a brush with individual bristles.
Fig. 6 A plan view of the bristle configuration without bristle carrier of the embodiment of fig. 5.
Fig. 7 A larger scale section through the head of a toothbrush.
Fig. 8 A larger scale detail of the section of fig. 6.
Fig. 9 A section corresponding to fig. 7 in a plane between adjacent bundles.
Fig. 10 A larger scale detail of the section of fig. 9.
Fig. 11 A plan view of the bristle configuration of the toothbrush of figs. 7 and 9.
Fig. 12 A section through a mounting support for the bundles in a first manufacturing stage.
Fig. 13 A section through a mould in a second manufacturing stage.
Fig. 14 A section XIV-XIV according to fig. 13. Fig. 15 A section XV-XV according to fig. 14. Fig. 16 A section XVI-XVI according to fig. 14.
Fig. 17 A view of the back of the support structure of
the bristle configuration manufactured in accor-

15
dance with figs. 12 to 16.
Fig. 18 A representation of the mounting support corresponding to fig. 12 in a method variant.
Fig. 19 The mounting support with part of the mould in a further method stage.
Fig. 20 A section with the mould closed in the bundle plane.
Fig. 21 A section of the closed mould in a plane between the bundles.
The embodiments of brushes shown in figs. 1 to 11 are manufactured in accordance with the method of the invention. The brush according to fig. 1 comprises a plastic bristle carrier 1 and bristles 2 combined to bundles 3 and which are melted to thickenings 4 at their fastening-side ends. By means of said thickenings 4 the bundles 3 are embedded, e.g. injection moulded into the bristle carrier 1, or are inserted in a thermoplastic process. The thickenings 4 of the bundles 3 are connected by means of a clearly defined support structure 5, which in the represented embodiment comprises webs 6 connecting neighbouring thickenings 4 and plastic-free recesses 7 located between the same.
In the embodiments according to figs. 3 to 6 individual, vertical bristles 2 are provided at their fastening-side ends with thickenings 4 by melting the bristle ends and shaped by the displacement of plastics material from the thickenings 4 to a plate-like support structure 8, the individual bristles 2 being combined into groups. In the embodiment according to fig. 5 the individual bristles 2 are mutually displaced, e.g. in the form of circular groups and

16
once again thickenings 4 are shaped to a support structure 9 with recesses 10.
Figs. 7 to 10 show the head 11 of a toothbrush with bundles 12, 13 having different shapes at the use-side end and which are also of different lengths. The fastening-side ends of said bundles are once again melted to form thickenings 4 and are interconnected by means of webs 6 through the displacement of the plastics material and which consequently form a support structure for the entire bristle configuration of bundles 12 and 13. The support structure and a short length of the bundles 12, 13 are once again embedded in the bristle carrier 1 of the brush head 11. The webs 6 between the thickenings can, as shown in figs. 8 and 10, be kept very thin and then form a type of joint between the individual bundles 12, 13, but still contribute to increasing the extraction resistance of the bundles 12, 13.
Figs. 12 to 16 show an apparatus for performing the method or for the manufacture of the brushes according to figs. 1 to 11. Fig. 12 shows a mounting support 15, where the bundles 16 forming a bristle configuration and which optionally have different diameters, are placed in channels 17. The bundles 16 are introduced by means of a not shown supply device into the channels 17 of the mounting support 15 and are appropriately fixed there in correspondingly narrow cross-sections of the channels 17 or the like by clips, plugs, etc. The supply takes place in such a way that the fastening-side ends 18 of the bundles 16 project over the mounting support 15. These fastening-side ends 18 are then melted in known manner, so that thickenings 19 are formed from the molten mass. A shaping device 14 (figs. 13 and 14) then comes into action and comprises individual male dies 21 associated with the thickenings and a closing unit formed from individual dies 22, which project over the male

17
dies 21 and are placed directly on the surface of the mounting support 15 between the thickenings 19. The male dies 21 also act against the thickenings 19 and displace the still soft plastic, but at least ductile plastics material to the side and said material is prevented from flowing further by the dies 22. In the area between the male dies 21 and the closing dies 22 can be provided further male dies 24 or a complete shaping unit 25, which displaces the plastics material to a clearly defined support structure, as shown in fig. 17 in a view of the rear of the support structure. It comprises thickenings 19, the thinner webs 26 connecting the same and the intermediate recesses 27.
The control during the displacement of the plastics material from the thickenings 19 takes place through the shaping contour of the shaping device 14 in conjunction with the closing pressure of the mould 20 against the mounting support 15. A further control possibility is illustrated in figs. 19 to 21. Here the bristle configuration comprises bundles 28 and 29 having a different cross-section. With the fastening-side end 30 or 31 thereof they are introduced to a differing extent into the channel 17 of the mounting support 15. The bristles are in each case melted to the length projecting over the mounting support 15, so that taking account of the spacings between the bundles 28, 29 sufficient plastics material is made available to bridge the spacings through a uniform thickness support structure 34. The mould 20 once again comprises male dies 21 and closing dies 22. The male dies 21 once again displace the material from the thickenings 32, 33 in all the mould cavities with the exception of the areas blocked off by the closing dies 22. This makes it possible to produce the support structure 34 shown in figs. 20 and 21 with an approximately constant cross-section despite the different cross

18
sections of the bundles 28, 29 and different spacings be tween the same.

19
CLAIMS
1. Method for the manufacture of brushes with a plastic bristle carrier and a bristle configuration of individual or bundlewise-combined plastic bristles fastened thereto, in that the fastening-side ends of the bristles or bundles are melted to a thickening, thickenings of adjacent bristles or bundles are interconnected by subsequent shaping and displacement of plastics material and the connections are subsequently embedded in the plastics material of the bristle carrier, characterized in that the thickenings {4, 19, 32, 33) are shaped by means of a mould. (20) to a clearly defined support structure (5, 9, 34) of webs (6, 26) connecting adjacent thickenings (4, 19, 32, 33) and then the support structure (5, 9, 34) and the bristles (2) projecting over the same are embedded in the plastics materials of the bristle carrier (1).
2. Method as claimed in claim 1, wherein that
plastic-free recesses (7, 10, 27) are formed between
the thickenings (4, 19, 32, 33) and the webs (6, 26)
connecting them.
3. Method as claimed in claim 1 or 2, wherein that
the thickenings (4, 19, 32, 33) are supported on their
bristle side and the plastics material displaced from
the thickenings (4, 19, 32, 33) during shaping for
forming the support structure {5, 9, 34) is controlled
by the closing pressure of the mould (20) against the
support.
4. Method as claimed in one of the claims 1 to 3, wherein
in that the plastics material displaced from

20
the thickenings (4, 19, 32, 33) during shaping for forming the support structure (5, 9, 34) is controlled by the length of the bristles (2) melted to the thickenings (4, 19, 32, 33).
5. Method as claimed in one of the claims 1 to 4, wherein
that the thickenings (4, 19, 32, 33) of more than two bristles (2) or bundles (3, 12, 13, 16, 28, 29) are shaped to a grid connecting them.
6. Method as claimed in one of the claims 1 to 5, wherein
that following the initial melting of the
fastening-side ends (18, 30, 31) of the bristles (2) or
bundles (3, 12, 13, 16, 28, 29), the thickenings (4,
19, 32, 33) are shaped with a time lag and in a still
plastic state to the connections.
7. Method as claimed in one of the claims 1 to 5, wherein
that after the initial melting of the fas
tening-side ends (18, 30, 31) of the bristles (2) or
bundles (3, 12, 13, 16, 28, 29), the thickenings (4,
19, 32, 33) are shaped to the connections with a time
lag and in a still ductile state.
8. Method as claimed in one of the claims 1 to 7 for the
manufacture of toothbrushes or hygiene brushes,
wherein that for obtaining a predetermined flexibil
ity of the bristle configuration the moment of inertia
of the bristle carrier (1) in the bending axis of the
bristle configuration and the plastic of the bristle
carrier (1) are so selected with respect to the modulus
of elasticity thereof that the flexibility of the bris
tle carrier (1) alone is greater than the predetermined
flexibility of the bristle configuration, and that the
number of connections of individual bristles (2) and/or

21
bundles (3, 12, 13, 16, 28, 29} and their moment of inertia acting in the bending axis, in conjunction with the moment of inertia of the thickenings (4, 19, 32, 33}, is at least locally selected in such a way that the flexibility of the bristle carrier (1} is damped to the amount predetermined for the bristle configuration.
9. Method as claimed in one of the claims 1 to 8, wherein
that the plastics material displaced from
the thickenings (4, 19, 32, 33) is shaped in the vicin
ity of the webs (6, 26) to a cross-section, whose ef
fective moment of inertia is lower than that of the
thickenings (4, 19, 32, 33).
10. Method as claimed in one of the claims 1 to 9, wherein
that, with respect to their moment of iner
tia, part of the webs (6, 26) is shaped to such an ex
tent that they act as joints.
11. Method for the manufacture of brushes with a plastic
bristle carrier and a bristle configuration of individ
ual or bundlewise-combined plastic bristles fastened
thereto, in that the fastening-side ends of the bris
tles or bundles are melted to a thickening and the
thickenings of adjacent bristles or bundles are inter
connected and the connections are subsequently embedded
in the plastics material of the bristle carrier, char
acterized in that a support structure (5, 9, 34), co
vering all the thickenings (4, 19, 32, 33), of webs (6,
26) connecting adjacent thickenings (4, 19, 32, 33) is
applied to and connected with the latter and that sub
sequently the support structure (5, 9-, 34) and the
bristles (2) are embedded in the
plastics material of the bristle carrier (1).

22
12. Method as claimed in one of the claims 1 to 11, wherein
that part of the support structure (5, 9,
34) is manufactured according to the method of one of
the claims 1 to 10 and the missing part according to
the method of claim 11 is applied to the preshaped sup
port structure (5, 9, 34).
13. Method as claimed in claim 11 or 12, wherein in
that a subsequently applied support structure (5, 9,
34) is connected by injection moulding to the thicken
ings (4, 19, 32, 33) or the preshaped support structure
(5, 9, 34) .
14. Apparatus for performing the method as claimed in one of
the claims 1 to 10 or 12, with a mounting support re
ceiving the bristles and/or bundles of the complete
bristle configuration of a toothbrush in channels, a
device for supplying the bristles and/or bundles in the
channels to a position in which their fastening-side
ends project over the mouth of the channels, a device
for melting the fastening-side ends and a shaping de
vice for the after-shaping of the melted ends, charac
terized in that the shaping device (14) has a male die
(21) associated with each thickening (4, 19, 32, 33)
for the lateral displacement of the plastics material
of the thickenings (4, 19, 32, 33) and at least one
shaping unit (25) located between the male dies (21)
for shaping the displaced plastics material to the con
nections between the thickenings (4, 19, 32, 33).
15. Apparatus as claimed in claim 14, wherein that
the shaping device (14) has at least one closing unit
for forming plastic-free spaces positioned between and
projecting with respect to the male dies (21) and which
can be placed an the mounting support (15).

23
16. Apparatus as claimed in claim 14 or 15, wherein
that at least the closing unit is in advance compared
with the male dies (21) and shaping unit (25).
17. Apparatus as claimed in claim 16, wherein that
the male dies (21) and shaping unit (25) are con
structed in one piece.
18. Apparatus as claimed in one of the claims 14 to 17,
wherein that the male dies (21) and shaping
unit (25) are separately controllable.
19. Apparatus as claimed in one of the claims 14 to 18,
wherein in that at least in predetermined areas,
the shaping face of the shaping unit (25) springs back
with respect to the shaping faces of the male dies
(21) .
20. Apparatus as claimed in claims 14 or 15, wherein
in that the closing unit, male dies (21) and shaping
unit (25) are constructed as a one-piece mould (20).
21. Apparatus as claimed in one of the claims 14 to 20,
wherein that the mounting support (15) with
the channel (17) receiving the bristles (2) and/or
bundles (3, 12, 13, 16, 28, 29) simultaneously serves
as an abutment for the shaping device (14).
22. Apparatus as claimed in one of the claims 14 to 21,
wherein that the shaping device (14) is at
least zonally provided with a heating device.
23. Apparatus as claimed in one of the claims 14 to 22,
wherein that the mounting support (15) with

24
the channels (17) receiving the bristles (2) and/or bundles (3, 12, 13, 16, 28, 29) simultaneously forms part of a mould for the bristle carrier (1) and during the filling of the mould shapes the bristle carrier (1)
at the bristle configuration side.

24. Apparatus as claimed in one of the claims 14 to 23,
wherein that the bristles (2) and/or bundles
(3, 12, 13, 16, 28, 29) in the mounting support (15)
are displaceable in the direction of the thickenings
(4, 19, 32, 33), which in the mould can be adjusted to
the desired embedding depth in the bristle carrier (1).
25. Brush, manufactured as claimed in the method of one of
the claims 1 to 13, comprising a plastic bristle car
rier and a bristle configuration of individual or bun-
dlewise-combined plastic bristles, provided at their
fastening-side ends with melted thickenings, by means
of which they are embedded in the bristle carrier,
characterized in that the bristles (2) and/or bundles
(3, 12, 13, 16, 28, 29) of the entire bristle configuration are connected by means of webs of the plastic of the bristles (2) connecting the thickenings (4, 9, 32, 33) and which form a support structure (5, 9, 34) increasing the resistance to extraction of the bristles.
26. Brush as claimed in claim 25,wherein that at
least zonally, the support structure (5, 9, 34) has a
smaller thickness than the thickenings (4, 19, 32, 33).

27. Brush as claimed in claim 25 or 26, wherein that the webs (6, 26) of the support structure (5, 9, 34) are constructed as joints.

25
28. Brush as claimed in one of the claims 25 to 27, wherein that the webs (6, 26), at least partly, are located in a different plane to the thickenings (4, 19, 32, 33) .
A method for the manufacture of brushes with a plastic bristle carrier and a bristle configuration of individual or bundlewise-combined plastic bristles is proposed, in that the fastening-side ends of the bristles or bundles are melted to a thickening, thickenings of adjacent bristles or bundles are interconnected by aftershaping and displacement of the plastics material and the connections are subsequently embedded in the plastics material of the bristle carrier. The thickenings are shaped by means of a mould to a clearly defined support structure of webs connecting adjacent thickenings and subsequently the support structure and the bristles projecting over the same are embedded by a short length in the plastics material of the bristle carrier. An apparatus for performing such a method and a brush manufactured by such a method are also proposed.

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Patent Number

207372

Indian Patent Application Number

IN/PCT/2002/00024/KOL

PG Journal Number

23/2007

Publication Date

08-Jun-2007

Grant Date

07-Jun-2007

Date of Filing

04-Jan-2002

Name of Patentee

CORONET-WERKE GMBH

Applicant Address

NEUSTADT 2, D-69483 WALD-MICHELBACH,

Inventors:

#	Inventor's Name	Inventor's Address
1	WEIHRAUCH GEORG	AM ROSSERT 1, D-69483, WALD-MICHELBACH,

PCT International Classification Number

A46B 3/06,

PCT International Application Number

PCT/EP00/06416

PCT International Filing date

2000-07-06

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	19932377.1	1999-06-13	Denmark