Method for Manufacturing a Brush

Abstract

A method for manufacturing a toothbrush having a bristle carrier made of a thermoplastic material with a front side and a rear side is provided. At least one recess formed as a blind hole in the bristle carrier extends from the front side in the bristle carrier, and holds at least one bristle. The at least one bristle is received in a receiving opening of a tool melted to form a thickening at its attachment-side end and inserted with its attachment-side end into the recess. The thermoplastic material is heated and, by pressing the tool against the front side of the bristle carrier, is deformed such that the thermoplastic material is displaced radially inwards into the recess, at least in the region of an edge surrounding the recess, for the form-fitting sealing of the thickening, in that a projection provided radially adjacent to the recess is pressed into the thermoplastic material.

Claims

1. A method for manufacturing a toothbrush, which has a bristle carrier made of a thermoplastic material with a front side and a rear side, wherein at least one recess formed as a blind hole in the bristle carrier extends from the front side in the bristle carrier, in which recess at least one bristle is held, in which the at least one bristle is received in a receiving opening of a tool, the at least one bristle is melted to form a thickening at its attachment-side end; the at least one bristle is inserted with its attachment-side end into the recess; the distance between the tool and the bristle carrier is reduced so that the tool contacts the bristle carrier, the thermoplastic material is heated and, by pressing the tool against the front side of the bristle carrier, is deformed such that the thermoplastic material is displaced radially inwards into the recess, at least in the region of an edge surrounding the recess, for the form-fitting sealing of the thickening, in that a projection provided radially adjacent to the recess is pressed into the thermoplastic material, the method comprising: applying a tool surface provided opposite the front side of the bristle carrier and corresponding to the contour of the front side of the bristle carrier to the projection in the direction of the bristle carrier in a planar manner against the front side at the end of the relative movement between the bristle carrier and the tool.

2. The method according to claim 1, wherein the projection acts on the front of the brush body in the form of ring segments lying on a ring surface.

3. The method according to claim 1, wherein the projection has a cross-sectional geometry tapering at one end.

4. The method according to claim 1, wherein the projection has a V-shaped cross-sectional geometry.

5. The method according to claim 1, wherein the projection has a dome-shaped cross-sectional geometry.

6. The method according to claim 1, further comprising heating the projection.

7. The method according to claim 1, further comprising heating the projection to a higher temperature than the tool surface, wherein the projection protrudes from the tool surface and the projection is assigned a heater provided on the tool by means of which the projection is heated.

8. The method according to claim 1, wherein the bristle carrier has a plurality of recesses and the tool has a plurality of receiving openings, in each of which a bristle bundle having a plurality of bristles is provided, further comprising: melting the bristle bundles to form a thickening; inserting the attachment-side end into the assigned recess, and displacing the edge surrounding the respective recess radially inwards into the recess for form-fitting sealing of the respective thickening, in that a projection provided radially adjacent to the respective recess is pressed into the thermoplastic material.

9. The method according to claim 1, wherein the bristle carrier still has an increased temperature due to the injection molding when the thickening is sealed in a form-fitting manner.

10. The method according to claim 1, further comprising holding the bristle carrier in a mold cavity segment at least partially molding the bristle carrier during form-fitting sealing of the thickening.

11. The method according to claim 9, further comprising removing the mold cavity segment together with the bristle carrier from an injection mold forming the bristle carrier before the form-fitting sealing of the thickening and is moved on a sealing section on which the thickening is sealed in and the bristle carrier is then removed from the mold cavity segment and the mold cavity segment is removed from the sealing section and inserted into the injection mold.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further details and advantages of the present invention will be apparent from the following description of an embodiment in conjunction with the drawing. Therein:

[0030] FIG. 1 shows schematic views of various stations of the method of processing, wherein in each station A-F perspective views of the respective components are shown from above and from below;

[0031] FIG. 2 shows a cross-sectional view of the bristle carrier and the tool prior to insertion of the thickening into a recess; and

[0032] FIG. 3 shows a cross-sectional view according to FIG. 2 after the thickening has been inserted into the recess;

[0033] FIG. 4 shows a cross-sectional view according to FIGS. 2 and 3 during sealing of the thickening in the recess, and

[0034] FIG. 5 shows a cross-sectional view according to FIG. 4 for an alternative form of projection.

DESCRIPTION OF THE INVENTION

[0035] In FIG. 1, A characterizes a placement station in which a tool 2 with a plurality of bristles 4 formed as a bristle bundle is filled with a plurality of filaments. For this purpose, the tool 2 has a plurality of receiving openings 6 in the form of holding channels. The respective bristles 4 project with their attachment-side end 8 over a tool surface 10.

[0036] In the heating station shown in FIG. 1B, the attachment-side end 8 of the bristles 4 is melted to form a thickening 12, for which purpose a heat source 14 is arranged opposite the tool 2. The heat from the heat source 14 melts all the filaments of a bristle 4 at the same time and forms them into a unit via the thickening 12. As usual, the thickening 12 projects radially beyond the bristle 4 after melting. Thus, the attachment-side end 8 of the bristle 4 is thicker than the diameter of the bristle 4 itself.

[0037] In station 10, the thickening 12 cools down.

[0038] In station 1D, a carrier plate 16 is arranged opposite the tool 2 and holds a bristle carrier 18. In the embodiment shown, the bristle carrier 18 comprises the head of a toothbrush with a plurality of recesses 20.

[0039] In FIG. 1E, the bristle carrier 18 and thus the carrier plate 16 and the tool 2 have been moved towards each other. In the course of this relative movement, the attachment-side end 8 with the thickening 12 is inserted into one of the recesses 20, which is shown in detail in FIGS. 2 to 4.

[0040] The sectional views according to FIGS. 2 to 4 show the oblong hole forming the receiving opening 6 in cross-sectional view. The bristle 4 is received therein. The thickening 12 projects beyond the tool surface 10. Furthermore, a projection 22 projects from the tool surface 10, which in the present case is configured to taper toward its free end. The projection 22 is configured as a self-contained ring and accordingly completely surrounds the bristle 4. The projection 22 projects from the otherwise planar tool surface 10. This tool surface 10 is otherwise just like a front surface of the bristle carrier 18 characterized by reference sign 24. This front surface 24 and the tool surface 10 have the same course. They are identically shaped.

[0041] The recess 22 forms a right-angled rim with the front surface 24, the boundary surface of which, lying in a front side 25, is characterized as an edge with reference sign 27.

[0042] The sectional view shown in FIGS. 2 to 4 also illustrates a heating assembly 28 underlying the projection 22 so that the projection 22 is heated to an elevated temperature.

[0043] Starting from the initial position shown in FIG. 2, the bristles 4 are brought closer to the tool 2. In this process, the thickening 12 is inserted into the recess 20 (FIG. 3). In the embodiment shown, this insertion movement is performed by moving a feed device 32, which comprises a plurality of feed pins 34 configured with the pattern of receiving openings 6 in the tool 2 and abutting against use-side ends 36 of all bristles 4, relative to the tool 2. As a result, the bristles 4 are moved toward and out of the tool 2 relative to each other. Initially, the distance of the tool 2 relative to the carrier plate 16 is not changed.

[0044] The thickening 12 finally abuts against a bottom of the recess 20, which is characterized by reference sign 30. Thereafter, the tool 2 is approached in the direction of the bristle carrier 18. The bristles and the feed device 32 remain stationary relative to the bristle carrier 18. As a result of this approach, the projection 22 contacts the front surface 24 of the bristle carrier 18 with its tapering end. As the distance between the tool 2 and the bristle carrier 18 is progressively reduced, the projection 22 is forced into the edge 27. In this process, the thermoplastic material softened by heating is displaced radially inwards into the recess 20. As a result, the thermoplastic material flows and deforms plastically. It approaches the outer circumference of the bristle 4, and if necessary the thermoplastic material also abuts against the outer circumference of the bristle 4. At the end of the deformation of the edge 27, the thermoplastic material covers the thickening 12 at reference sign 38. As a result, the thickening 12 is positively sealed in the bristle carrier 18 (cf. FIG. 4).

[0045] Subsequently, the distance between the tool 2 and the bristle carrier 18 is increased. The bristle 4 remains stationary due to the form-fit retention of the thickening 12 in the bristle carrier 18. The tool 2 is removed, leaving the bristle 4 in the bristle carrier 18.

[0046] In FIG. 1, the feed device 32 is omitted in favor of a clear graphical representation. After removal of the tool 18, a brush is obtained, characterized by reference sign 40, which consists of the injection-molded bristle carrier 18 and the bristles 4.

[0047] It is understood that the bristle carrier 18 can be manufactured during preparation by injection molding as a multi-component injection molded part with different material components including at least one elastomeric component. In FIG. 1, reference sign 42 characterizes an injection mold formed by two mold halves 44, 46. The upper mold half, characterized by reference sign 44, has a carrier plate receptacle 48 in which the carrier plate 16, reproduced in position A1 for itself with the bristle carrier 18, is received. As shown schematically in FIG. 1, the carrier plate 16 is returned from position E to the injection mold 42. Thus, the carrier plate 16 is removed from a sealing section characterized by reference sign 50 and reused for molding the bristle carrier 18. In the area of the injection mold 42, reference signs 52 characterize pins provided on the lower mold half 46 in the cavity forming the bristle carrier 18.

[0048] FIG. 1 also shows that the tool 2 remains on the sealing section and, after removal of the bristles 4 (see position F), is returned to position A and provided with bristles 4.

[0049] By removing the bristle carrier 18 from the injection mold 42, the bristle carrier 18 can still be handled at a relatively high temperature. Thus, the approach of the mold 2 to seal in the bristles 4 occurs at a temperature at which the material of the bristle carrier 18 is still heated by the injection molding cycle. Thus, the energy expended for the injection molding process is used to keep the thermoplastic material of the bristle carrier 18 as soft and flowable as possible with respect to the sealing-in of the bristles 4. Accordingly, the method according to the invention can be carried out in a particularly resource-saving manner.

[0050] FIG. 6 shows an alternative cross-sectional configuration of the projection 22, which results in a different deformation behavior of the thermoplastic material when the tool 2 and the bristle carrier 18 approach each other. Here, the projection 22 has a cylindrical base which is provided with a dome, i.e. covered by a semicircular cap.

LIST OF REFERENCE SIGNS

[0051] 2 tool [0052] 4 bristle [0053] 6 receiving opening [0054] 8 attachment-side end [0055] 10 tool surface [0056] 12 thickening [0057] 14 heat source [0058] 16 carrier plate [0059] 18 bristle carrier [0060] 20 recess [0061] 22 projection [0062] 24 front surface [0063] 25 front side [0064] 26 rim [0065] 27 edge [0066] 28 heating assembly [0067] 30 bottom [0068] 32 feed device [0069] 34 feed pin [0070] 36 use-side end [0071] 38 cover [0072] 40 brush [0073] 42 injection mold [0074] 44 upper mold half [0075] 46 lower mold half [0076] 48 carrier plate receptacle [0077] 50 sealing section [0078] 52 pin