DE102019105305A1 - Method for manufacturing a brush and bristle carrier and magazine for carrying out the method - Google Patents

Abstract

A method for producing a brush provides that a one-piece, injection-molded bristle carrier (10) has sleeve-like bundle receptacles (22) which are coupled to a central support structure (18) via a thin connecting web (20). This bristle carrier is overmolded with a soft plastic (26). After inserting the bundles of bristles (24), the bundle receptacles (22) are narrowed at the front by heat and pressure. Furthermore, an overmolded bristle carrier and a magazine for carrying out the method are presented.

Description

The invention relates to a method for producing a brush and a bristle carrier and a magazine.

In the manufacture of brushes, in particular toothbrushes, the fastening of the bristle bundles by means of anchors and the anchorless fastening of the bristle bundles have become established in practice. The present invention relates solely to anchorless fastening. During the injection molding process, a previously injected bristle carrier is provided with openings into which bundles of bristles are inserted. The rear ends of the bristles of a bristle bundle are fused together by thermal heating before the bundle is inserted into the openings. This creates a thickening of the material that can be similar to a mushroom. The individual bristles are fused using hot air or a stamp.

From the DE 10 2016 107 759 A1 a method is known which deals with a novel fastening of the bristle bundles on the bristle carrier. For this purpose, after the bristles have been inserted into the so-called anchoring opening, the front side of the bristle carrier is heated and pressurized so that the wall surrounding the receiving opening is deformed and narrowed in the area of its mouth towards the front, so that the bristle bundle is fixed with its thickened end in the anchoring opening . The front side of the bristle carrier is brought to a temperature which is below the melting temperature of the bristle material and / or the bristle carrier material, in particular a maximum of 85% in ° C. of the respective melting temperature. The heat that is applied to the bristle carrier is introduced via a tool part called a magazine or perforated plate. In the magazine or the perforated plate there are openings which have received the bristle bundles and from which the bristle bundles are pressed out into the anchoring openings. This method has the advantage that the bristle bundles are held in the bristle carrier so that they are extremely resistant to pulling out without additional anchor means. In addition, the anchoring opening is made narrower around each bundle of bristles, so that no impurities can settle here at the transition into the anchoring opening.

The invention uses this in the DE 10 2016 107 759 A1 The method shown, also with the temperatures and pressures described there, in order to create a brush which has a high flexibility of the individual bristle bundles relative to other bristle bundles.

The individual mobility of the bristle bundle to the brush handle is increasingly desired for many applications. The WO 2006/131397 A1 shows a bristle carrier plate, which is mounted movably in all directions via articulated feet on the bristle carrier. The individual bundles of bristles are inserted into sleeve-like, highly elastic mountings that are significantly softer than the bristle carrier. They should allow the bristle bundles to evade.

A similar procedure shows the WO 97/20484 A1 , in which the bristle bundles are also received in a soft, elastic mass, which has sleeve-like extensions and which is received in a hard brush holder.

The object of the invention is to provide a method for producing a brush which can be carried out easily and safely, leads to a high quality of the brush and ensures the elasticity and mobility of the bristle bundles in relation to the bristle handle.

• Vorsehen eines einstückigen, spritzgegossenen Borstenträgers mit hülsenartigen, vorderseitig offenen Bündelaufnahmen, die jeweils über zumindest einen Verbindungssteg in eine zentrale Tragstruktur übergehen,
• Umspritzen des Borstenträgers mit einem weicheren Kunststoff, d. h. einem Kunststoff, der weicher als der Kunststoff des Borstenträgers ist, unter Einbetten der Bündelaufnahmen und Ausfüllen von Zwischenräumen zwischen Bündelaufnahmen untereinander und zwischen Bündelaufnahmen und Tragstruktur,
• Einschieben von Borstenbündeln in die Bündelaufnahmen, und
• Umformen der Bündelaufnahmen an deren vorderem Rand unter Aufbringen von Wärme und Druck und dadurch Arretieren der Bündel in der Bündelaufnahme.

This is achieved in the method according to the invention with the following steps:

• Provision of a one-piece, injection-molded bristle carrier with sleeve-like, frontally open bundle receptacles, each of which merges into a central support structure via at least one connecting web,
• Overmolding of the bristle carrier with a softer plastic, ie a plastic that is softer than the plastic of the bristle carrier, with embedding of the bundle receptacles and filling of gaps between bundle receptacles and between bundle receptacles and support structure,
• Insertion of bundles of bristles into the bundle receptacles, and
• Reshaping of the bundle receptacles at their front edge by applying heat and pressure and thereby locking the bundle in the bundle receptacle.

In contrast to the prior art, the method according to the invention provides that the bundles sit in bundle receptacles which are made from a hard plastic, ie from a harder plastic than the overmolding material. This plastic is shaped by the temperature and heat in order to compress and narrow the bundle receptacles at the mouth. The flexibility of the individual bundles in relation to one another and in relation to the bristle handle is achieved in that the sleeve-shaped bundle receptacles are only connected to the central support structure via at least one thin web. However, the bridge would not be able to improve the stability of the To maintain the bristle carrier during use. By overmolding the bristle carrier with a softer plastic, the entire then completed bristle carrier becomes more stable overall, it receives a smooth, closed outer surface, but the hard bundle receptacles in the soft plastic are still movable.

The forming of the bundle receptacles with the application of pressure and heat takes place as in the aforementioned DE 10 2016 107 759 A1 , which are explicitly referred to in this regard.

The bundle receptacles are preferably brought to a temperature which is at most 85% in ° C. of the melting temperature of the bristle carrier material, specifically after the bristle carrier has been encapsulated with the softer plastic.

The heating takes place z. B. via a heated magazine in which the bundles are received and from which the bundles are pushed into the bundle receptacles in the bristle carrier. The magazine presses against the bundle receptacles and heats them with simultaneous deformation at the front edge, with “front” being the front of the brush from which the bundles protrude, and the back being the opposite side of the brush, which is usually provided without brushes.

The rear side of the overmolded bristle carrier is actively cooled during the reshaping and heating, by a cooling device, preferably a fluid-cooled or even water-cooled cooling device.

After the extrusion coating, the bristle carrier can have at least one section that is exposed to the adjacent soft plastic and is in particular the support structure.

This exposed section can then be used on the one hand to provide support when the molded brush holder is reshaped and on the other hand to provide cooling. There is preferably a complementary receptacle on the tool side, into which the overmolded bristle carrier is inserted and in which it is supported and cooled.

After the tool has been closed and the sleeve-like bundle receptacles have been reshaped, the tool will preferably remain in this position for a few seconds, which represents a predetermined holding time. This holding time should be at least 1 second, in particular at least 1.5 seconds and / or a maximum of 3 seconds before the tool is opened.

In addition to the holding time, there is also a period of time in which the tool is first moved into the closed position and in which heat is already introduced into the bristle carrier and pressure is exerted on the bristle carrier. The entire period of time, from the first contact of the magazine with the bristle carrier up to the removal of the magazine from the bristle carrier, is referred to as the exposure time, in which the holding time forms a part. The exposure time is preferably at least 4, in particular at least 5 seconds.

In order to keep the flexibility of the bundle receptacles as high as possible, but at the same time to keep the resulting brush head smooth, it is provided that the webs on the back and sides are completely surrounded by the softer plastic and thus covered by it. The webs are also completely covered on the front side by the soft plastic, but the bundle receptacles protrude from the soft plastic on the front side, so that the plastic does not bear against the bundle receptacles over the entire depth and stabilize the bundle receptacles along the entire depth.

On the rear side, the bundle receptacles can be exposed to the soft plastic, e.g. punctiform in order to achieve support during forming. For this purpose, it is conceivable that a thin pin protrudes from the rear of the bundle receptacles, which is then exposed on the front side opposite the soft plastic.

The invention also relates to an overmolded brush holder for producing a bristle by means of the method according to the invention. The brush holder is formed by an injection-molded brush holder with several sleeve-like, frontally open bundle receptacles, each of which merges into a central support structure via preferably only a single connecting web, the brush holder being overmolded with a softer plastic and the bundle receptacles embedded in the plastic and open on the front . The plastic completely fills the spaces between the bundle holders and between the bundle holders and the support structure.

The back of the supporting structure is preferably exposed in relation to the adjacent, soft plastic, so that support on the harder supporting structure is then possible during manufacture.

The webs preferably have a smaller height and / or width in plan view of the open side of the bundle receptacle than the bundle receptacles themselves, ie their cross section. This ensures that the bundle recordings are stable per se, but they are movable relative to the support structure and thus to the brush handle.

The support structure can merge in one piece into the brush neck and / or into the brush handle, i. H. Be part of it.

In general, an elongated structure can be provided as the supporting structure, which extends centrally and elongated through the brush head.

As mentioned, the bundle receptacles can protrude on the front side with respect to the soft plastic and / or be exposed on the rear side with respect to the plastic without protruding.

The invention also relates to a magazine, also called perforated plates, into which bundles of bristles are inserted, the ends of which are then fused at the back, with the deformation of the bundle receptacles taking place via the magazine. The magazine according to the invention has holes for receiving the bundle of bristles, the holes having an enlarged cross-section at their end near the bundle receptacles in order to form individual depressions into which the bundle receptacles penetrate and are laterally supported during forming, the depressions being converted into a step Pass the reduced hole cross-section and the depressions end at a tapered step.

The sleeve-shaped bundle receptacles can be supported laterally through the depressions when they are deformed. The deformation takes place in particular by means of a conically tapering step on the end face of the bundle receptacles. Bundle receptacles themselves can have a corresponding conical shape at their free end in the non-deformed state. This prevents the sleeve-shaped bundle receptacles from bulging outwards as a result of the pressure on the face side and receiving a geometry that cannot be precisely predefined when pressure is applied.

Furthermore, the magazine can have an integrated heating device.

• - 1 eine Querschnittsansicht durch eine erfindungsgemäß hergestellte Bürste in Form einer Zahnbürste mit einem erfindungsgemäßen Borstenträger gemäß der Linie I-I in 2,
• - 2 eine Draufsicht auf den erfindungsgemäßen, umspritzten Borstenträger, der in 1 vorhanden ist,
• - 3 eine Rückseite der Bürste nach 1,
• - 4 eine Schnittansicht durch ein Werkzeug samt erfindungsgemäßem Magazin und einen in das Werkzeug eingelegten, erfindungsgemäßen Borstenträger, geschnitten längs der Linie IV-IV in 2 vor dem Umformen,
• - 5 eine Schnittansicht durch ein Werkzeug samt erfindungsgemäßem Magazin und einen in das Werkzeug eingelegten, erfindungsgemäßen Borstenträger, geschnitten längs der Linie IV-IV in 2 beim Umformen, und
• - 6 eine vergrößerte Ansicht des Werkzeugs und des umgeformten Borstenträgers in einem Detail.

Further features and advantages of the invention emerge from the following description and from the following drawings, to which reference is made. In the drawings show:

• - 1 a cross-sectional view through a brush produced according to the invention in the form of a toothbrush with a bristle carrier according to the invention along the line II in FIG 2 ,
• - 2 a plan view of the molded bristle carrier according to the invention, which is shown in FIG 1 is available,
• - 3 one back of the brush after 1 ,
• - 4th a sectional view through a tool including a magazine according to the invention and a bristle carrier according to the invention inserted into the tool, sectioned along the line IV-IV in FIG 2 before forming,
• - 5 a sectional view through a tool including a magazine according to the invention and a bristle carrier according to the invention inserted into the tool, sectioned along the line IV-IV in FIG 2 when forming, and
• - 6th an enlarged view of the tool and the deformed bristle carrier in a detail.

In 1 a toothbrush is shown with a bristle carrier 10 , made of thermoplastic material, which in this case has a section that goes into the brush head 12 protrudes and the brush neck 16 as well as the stem 14th includes.

The bristle carrier 10 is in 2 shown in more detail. The neck 16 goes in one piece into a central, a continuation of the neck 16 representing elongated supporting structure 18th over that part of the brush head 12 is. The supporting structure 18th is a one-piece section which is arranged in the middle, ie in the longitudinal axis of the toothbrush.

From the supporting structure 18th and side bars are integrally connected to it 20th from, which run to sleeve-shaped bundle receptacles and integrally in these bundle receptacles 22nd pass over.

The bundle recordings 22nd are open to the front and to the rear (see 1 ) closed, so they have a pot shape.

By having the webs 20th both in their width, which in 2 can be seen, as well as in their height, which is partly in 4th can be seen, less than the corresponding bundle uptake 22nd is, form the webs 20th a kind of flexible bridge between the bundle receptacle 22nd and the supporting structure 18th so that these bundle shots 22nd flexible in all directions on the supporting structure 18th are attached.

The bristle carrier 10 is done before having bundles of bristles 24 is filled with a soft plastic 26th encapsulated in the area of the brush head 12 . In 2 is the outline of the soft plastic in broken lines 26th shown. "Soft" means softer than the plastic of the bristle carrier 10 .

The soft plastic 26th fills the spaces between adjacent bundle receptacles 22nd and their bars 20th as well as between the bundle recordings 22nd and the supporting structure 18th completely off.

The soft plastic 26th also covers the back (see 3 ) and laterally as well as the bars 20th so that they cannot be felt from the back.

The bundle pickups 22nd exposed on the back at points. At the sides, however, they are completely covered by soft plastic.

The central supporting structure 18th however, the back is not made of soft plastic 26th covered and is thus exposed on the back.

The soft plastic covers the front 26th all bridges 20th . The bundle recordings 22nd however, as in the 1 and 4th can be seen, compared to the soft plastic 26th forward and protrude from this.

The method for making a brush is described in more detail below.

First, as already said, the bristle carrier 10 injected, and then he is in the area of the head 12 with the soft plastic 26th encapsulated.

Then this overmoulded bristle carrier is 10 in a tool which is in the 4th and 5 is shown, inserted. The tool has a lower tool half 30th with a receptacle that corresponds to the shape of the molded bristle carrier 10 in the area of the brush head 12 and possibly also the area of the neck 16 corresponds to and is complementary to this. The overmolded bristle carrier is thus located 10 on the back with the supporting structure 18th and the adjacent soft plastic 26th over the entire surface of the lower mold half 30th on.

Provided the bundle recordings 22nd If the back is exposed to the plastic (without protruding), they are also supported directly on the back of the mold half 30th from.

In a so-called magazine 32 , also called perforated plate, are bundles of bristles 24 used. These bundles of bristles 24 are at one end with a thickening 34 provided, which is formed in that the bristles of a bristle bundle 24 are fused together. This fusing can optionally take place after the bristle bundle 24 in the magazine 32 were plugged.

With the thickening 34 ahead are the bristle bundles 24 into the sleeve-shaped bundle receptacles, which are open at the front 22nd inserted, if necessary with the help of a plunger or compressed air. This is possible via the corresponding arrows in 4th symbolizes. The magazine 32 is preferably made of metal or ceramic and has a heating device 36 on, e.g. B. an electric heater or a hot water heater. Alternatively, a heater is attached to the magazine 32 coupled before the forming process.

The magazine 32 has holes 33 to accommodate the bristle bundle 24 , with the holes 33 on her the bundle recordings 22nd near end have an enlarged cross-section to accommodate individual depressions 35 to form into which the bundle recordings 22nd penetrate and support themselves laterally during forming, the depressions 35 via a tapered step 37 merge into a reduced hole cross-section and the depressions 35 at the tapered step 37 end up.

The step can be conical or dome-shaped, as shown in the figures.

The bundle recordings 22nd can have a conical front edge on the outside 39 have, which is optional, not mandatory, opposite of the deepening 35 and the stage 37 can be formed. In 6th can even be seen that the bundle shots 22nd undeformed conical at the edge, but that the step 37 is dome-shaped and the bundle receptacles 22nd thus brought into a dome shape.

Through the depressions 35 can use the sleeve-shaped bundle receptacles 22nd be supported laterally if they are deformed (see 5 ).

The deformation takes place in particular by means of the tapered step 37 at the front of the bundle receptacles 22nd . This prevents the sleeve-shaped bundle receptacles from being reshaped 22nd bulge outwards due to the frontal pressure and obtain a geometry that cannot be precisely predefined.

With the bottom of the magazine 32 ahead is the magazine 32 against the bristle carrier 10 driven and hits against the top of the bundle receptacles 22nd (please refer 5 ). By having the magazine 32 If the front is heated, the plastic becomes the bundle receptacles 22nd soft at the front end, but remains below its melting temperature. Preferably, the front of the bundle receptacles 22nd brought to a temperature which is at most 85% in ° C of the melting temperature of the material of the bristle carrier 10 corresponds. The temperature of the magazine is also preferred 32 on contact with the bristle carrier 10 brought to 60 ° C to 200 ° C, in particular above 80 ° C, preferably below 150 ° C.

The magazine 32 is on the lower half of the tool 30th to driven so that the bundle recordings 22nd reshaped inward on the front side, as shown in 6th based on the left Bundle pickup 22nd is shown. The cross section of the opening of the bundle receptacles 22nd is significantly reduced in the end area so that, as in 6th is represented symbolically, the resulting narrowed opening is significantly smaller than the thickening 34 .

In 6th is the right bundle recording 22nd undeformed and the middle one is also shown undeformed, with the middle bundle recording 22nd the bundle of bristles 24 is plugged in. Optionally, the bundle pick-up 22nd can even be pressed so that they are around the thickening 34 and put the bristles around it. Alternatively, it is in the area inside the opening 38 , ie within the bundle receptacle 22nd another gap between the bristles and the bundle holder 22nd forming wall. However, the narrowest point is the bundle intake 22nd preferably, this is not to be understood as restrictive, so closely that the outer bristles are contacted.

How 6th shows the bundle pickup 22nd axially shortened by the deformation, from the original height H to the height H ', which is shorter by 1-1.3 mm, in particular 1.2 mm.

Preferably be magazine 32 and tool half 30th moved to block (see 5 where contact has not yet been fully achieved), ie they are against each other. After a certain holding time and exposure time, the magazine then becomes 32 moved upwards, causing the bundle 24 from the openings in the magazine 32 wander out.

During the forming process, the lower half of the tool 30th cooled because they have an active cooling device 40 is provided, for example by cooling water passed through channels. Any active air cooling is also possible. The temperature of the bristle carrier 10 on the back of the supporting structure 18th is preferably not more than 30 ° C because of the cooling means 40 .

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102016107759 A1 [0003, 0004, 0010]
• WO 2006/131397 A1 [0005]
• WO 9720484 A1 [0006]

Claims (16)

Method of making a brush, with the steps Providing a one-piece, injection-molded bristle carrier (10) with sleeve-like, frontally open bundle receptacles (22), each of which merges into a central support structure (18) via at least one connecting web (20), Overmoulding the bristle carrier (10) with a softer plastic (26), embedding the bundle receptacles (22) and filling the gaps between bundle receptacles (22) with one another and between bundle receptacles (22) and support structure (18) with the soft plastic (26), Inserting bundles of bristles (24) into the bundle receptacles (22), and Reshaping of the bundle receptacles (22) at their front edge while applying heat and pressure and thereby locking the bristle bundles (24) in the bundle receptacles (22). Procedure according to Claim 1 , characterized in that for reshaping the bundle receptacles (22) are heated to a temperature which is at most 85% in ° C of the melting temperature of the material of the bundle receptacles (22). Procedure according to Claim 1 or 2 , characterized in that a heated magazine (32), in which the bristle bundles (24) are received and from which the bristle bundles (24) are pushed into the bundle receptacles (22), is pressed against the bundle receptacles (22) and the bundle receptacles ( 22) is heated and reshaped by applying pressure. Method according to one of the preceding claims, characterized in that the rear side of the overmolded bristle carrier (10) is actively cooled during the forming and heating. Method according to one of the preceding claims, characterized in that the bristle carrier (10) is exposed on the rear side opposite the adjacent, softer plastic (26) after being encapsulated with the soft plastic (26), in particular exclusively on the support structure (18). Method according to one of the preceding claims, characterized in that, during the reshaping, the overmolded bristle carrier (10) is supported over the entire surface in a complementary receptacle. Method according to one of the preceding claims, characterized in that the undeformed bundle receptacles (22) have a conically tapering front edge (39) on the outside. Method according to one of the preceding claims, as far as Claim 3 referred back, characterized in that the magazine (32) has holes (33) for receiving the bundle of bristles (24), the holes (33) having an enlarged cross-section adapted to the bundle receptacles (22) at their end near the bundle receptacles (22) to form individual depressions (35) into which the bundle receptacles (22) penetrate and are laterally supported during forming, the depressions (35) merging via a step (37) into a hole cross-section which is adapted to the bristle bundle (24) . Procedure according to Claim 8 , characterized in that the depressions (35) end at a tapered step (37). Overmoulded bristle carrier for producing a brush by means of the method according to one of the preceding claims, characterized in that an injection-molded bristle carrier (10) is provided with several, sleeve-like, frontally open bundle receptacles (22), the bundle receptacles (22) each preferably having only one respectively associated connecting web (20) merge into a central support structure (18), the bristle carrier (10) being overmolded with a plastic (26) that is softer than the material of the bristle carrier (10) and the bundle receptacles (22) in the softer plastic (26) ) are embedded and open at the front, the softer plastic (26) filling the spaces between the bundle receptacles (22) and between the bundle receptacles (22) and the support structure (18). Bristle carrier after Claim 10 , characterized in that the support structure (18) and / or the bundle receptacles (22) are each exposed on the rear opposite the adjacent, softer plastic (26), preferably completely surrounded by it on the sides, and / or that the connecting webs (22) on the rear and are completely surrounded on the sides by the softer plastic (26) and are only exposed on the front side with respect to the softer plastic (26). Bristle carrier after Claim 10 or 11 , characterized in that the connecting webs (20) have a smaller height and / or width seen in plan view of the open side of the bundle receptacles (22) than the bundle receptacles (22). Bristle carrier according to one of the Claims 10 to 12 , characterized in that the support structure (18) merges in one piece into the brush neck (16) and / or the brush handle (14). Bristle carrier according to one of the Claims 10 to 13 , characterized in that the The bundle receptacles (22) protrude on the front opposite the softer plastic (26). Magazine for carrying out the method according to one of the Claims 1 to 9 , characterized in that the magazine (32) has holes (33) for receiving the bundles of bristles (24), the holes (33) having an enlarged cross-section at their end near the bundle receptacles (22) in order to close individual recesses (35) form into which the bundle receptacles (22) penetrate and are laterally supported during forming, the recesses (35) merging into a reduced hole cross-section via a step (37) and the recesses (35) end at a tapered step (37). Magazine after Claim 15 , characterized in that the magazine (32) has an integrated heating device (36).

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