Method for Manufacturing Bristle Products, Bristle Product Manufacturing Machine, Bristle Product, and Use of a Fastening Anchor Made of Plastics Material

This application claims priority from German Patent supplication No. 10 2024 112 486.5, filed May 3, 2024, which is incorporated herein by reference as if fully set forth.

The invention relates to a method for manufacturing bristle products, for example toothbrushes, wherein a bristle carrier provided with at least one bundle receptacle bore is provided, and a bristle bundle is incorporated conjointly with a fastening anchor into the bundle receptacle bore and anchored in the latter by means of a fastening anchor.

The invention furthermore also relates to a bristle product manufacturing machine which is specified to manufacture bristle products, and to a bristle product and to the use of a fastening anchor.

EP 0 888 072 B1 discloses a method for manufacturing a brush, in particular a toothbrush, having a bristle body that supports bristle bundles made of plastics material. In the method, sleeve-type supporting elements made of plastics material, which enclose the individual bristle bundles, are manufactured integrally with the bristle body for at least part of the bristle bundles by an injection-molding procedure.

DE 197 38 256 C2 discloses a method for manufacturing bristle fields for brushes, wherein bundles of plastic bristles are introduced into perforations of a holding plate, and the ends of said plastic bristles that face away from their later free working ends are fused to one another and are fixedly established on the holding plate as a result. Protrusions having heads, widenings or projections are formed on the holding plate, the holding plate as a result being provided with undercuts. Prior thereto, or thereafter, the bristles are introduced into the perforations so as to have a projection that protrudes into the region of the protrusions or the undercuts, whereby the bristles in the region of the protrusions or the undercuts are heated in such a manner that a melt and/or a plastic mass consisting of the plastics material of the bristles is created that completely or partially fills the undercuts. As a result of the subsequently solidifying mass of the plastics material of the bristles, a form-fit is formed between the bristles or bristle bundles and the undercuts of the holding plate.

When manufacturing bristle products, in particular toothbrushes, bristle bundles are fixed in the bundle receptacle bores of the bristle carriers of bristle products of this type by way of fastening anchors.

For this purpose, the bristle bundles are incorporated conjointly with the fastening anchors into the bundle receptacle bores of the bristle carriers. In practice, fastening anchors made of metal, for example stainless steel, are often used in the process in order to reliably anchor the bristle bundles in the bundle receptacle bores. The bristle bundles can indeed be reliably fixed in the bundle receptacle bores with the aid of fastening anchors of this type made of metal. However, the use of fastening anchors made of metal in a bristle product in which the other constituent parts are composed of a different material, in particular of plastics material, may impede the recycling of the bristle product.

It is therefore an object of the invention to provide a method for manufacturing bristle products, a bristle product manufacturing machine, a bristle product and the use of a fastening anchor, which enable reliable anchoring of bristle bundles in bristle carriers of bristle products, and at the same time simplify the recycling of bristle products of this type.

Proposed for achieving the object is firstly a method for manufacturing bristle products, having one or more of the features disclosed herein directed toward a method of this type. Proposed in particular for achieving the object is thus a method for manufacturing bristle products, wherein a bristle carrier provided with at least one bundle receptacle bore is provided, and a bristle bundle is incorporated conjointly with a fastening anchor into the bundle receptacle bore and anchored in the latter by means of the fastening anchor, wherein the fastening anchor during incorporation into the bundle receptacle bore is deformed while forming at least one end-proximal anchoring structure. A fastening anchor which is composed of plastics material is preferably used in the process. The fastening anchor can preferably be plastically deformed while forming the at least one anchoring structure during incorporation into the bundle receptacle bore. The method enables the manufacturing of a single-material bristle product, the recycling of the latter being significantly simplified.

In comparison to the use of fastening anchors which are not deformed during the incorporation of the bristle bundles into the bundle receptacle bores, but are instead pushed into the material of the bristle carriers in order to anchor the bristle bundles in the bundle receptacle bores, the method according to the invention utilizes the deformation of a fastening anchor in the bundle receptacle bore so as to cause reliable fixing of the bristle bundle in the bristle carrier.

When the fastening anchor is incorporated conjointly with the bristle bundle into the bundle receptacle bore, in particular pushed into the latter, the fastening anchor is deformed while forming at least one end-proximal anchoring structure which enables reliable anchoring of the bristle bundle in the bundle receptacle bore.

The at least one anchoring structure during incorporation of the fastening anchor into the bundle receptacle bore can be generated due to contact between the fastening anchor and a bore wall of the bundle receptacle bore. In the process, the bristle carrier by way of its bundle receptacle bore functions as a shape-imparting tool, so to speak, which deforms the fastening anchor in such a way that the at least one end-proximal anchoring structure is formed on the fastening anchor.

An end-proximal thickening, for example a cudgel-shaped thickening, can be generated as at least one end-proximal anchoring structure.

In particular when the fastening anchor during incorporation into the bundle receptacle bore is symmetrically deformed, one end-proximal thickening on both ends of the fastening anchor can be formed as end-proximal anchoring structures. The fastening anchor can assume a bone shape.

It is also possible that the fastening anchor during incorporation into the bundle receptacle bore is asymmetrically deformed, thus an anchoring structure being formed only at one of the two ends of the fastening anchor, for example. It is also possible that anchoring structures are asymmetrically formed at two ends of the fastening anchor.

It can be advantageous also to compress the fastening anchor upon incorporation into the bundle receptacle bore. This can take place, for example, by a thruster tongue of a stuffing tool of a bristle product manufacturing machine. By compressing the fastening anchor upon incorporation into the bundle receptacle bore, the fastening anchor can be deformed in a particularly targeted manner so as to form the at least one end-proximal anchoring structure and to effect the reliable anchoring of the bristle bundle in the bundle receptacle bore in the bristle carrier.

In one variant of the method, the fastening anchor is compressed upon incorporation into the bundle receptacle bore and, as a result, a filling level of the bristle bundle is increased. In the process, a filling level of at least 65% or else of at least 72% can be achieved. The targeted compression of the fastening anchor can then lead to a deformation of the fastening anchor which leads to a displacement of the bristle filaments of a bristle bundle fixed in the bundle receptacle bore by the fastening anchor, said bristle filaments resting on the fastening anchor. As a result, the filament density in the volume of the bundle receptacle bore occupied by the bristle filaments can be increased, and the filling level of the bristle bundle can be increased in this way. Bristle products having particularly dense bristle bundles can be manufactured in this way by the method.

In one variant of the method it is provided that the fastening anchor upon incorporation into the bundle receptacle bore is compressed and, as a result, an extraction force which is withstood by the fixing of the bristle bundle in the bristle carrier is increased. The extraction force herein can be the force which has to be applied in order to overcome the retaining force provided by the fastening anchor and to release the bristle bundle from the bundle receptacle bore.

During incorporation of the fastening anchor into the bundle receptacle bore, material of the bristle carrier can be displaced from a peripheral region of the bundle receptacle bore into the bundle receptacle bore and over the fastening anchor placed in the bundle receptacle bore. The displacement of the material of the bristle carrier can take place, for example, by a thruster tongue of a stuffing tool of a bristle product manufacturing machine. This will be explained in more detail hereunder in the context of the bristle product manufacturing machine according to the invention.

The material of the bristle carrier which is displaced from the peripheral region of the bundle receptacle bore into the bundle receptacle bore can be displaced by way of the anchoring structure which has been generated on the fastening anchor as a result of the deformation of the fastening anchor. In this way, a form-fitting fixing of the fastening anchor in the bundle receptacle bore of the bristle carrier is established.

The fastening anchor and the bristle carrier during incorporation of the fastening anchor into the bundle receptacle bore can be connected to one another in a materially integral manner. The bristle carrier and the fastening anchor can be adhesively bonded and/or welded to one another in the process.

The fastening anchor and the bristle carrier can be adhesively bonded and/or welded to one another, thus the materially integral connection between the fastening anchor and the bristle carrier can be established, by frictional heat generated during the incorporation of the fastening anchor into the bundle receptacle bore.

In order to facilitate the materially integral connection between the bristle carrier and the fastening anchor, the bristle carrier can be heated prior to and/or upon incorporation of the fastening anchor. This takes place in particular in the region of the at least one bundle receptacle bore.

For forming the at least one anchoring structure on the fastening anchor during incorporation of the fastening anchor in the bundle receptacle bore it is advantageous when a length of the fastening anchor is larger than a diameter of the bundle receptacle bore into which the fastening anchor for anchoring a bristle bundle is incorporated.

In this way, the portions of the fastening anchor that project beyond the periphery of the bundle receptacle bore are correspondingly deformed during incorporation of the fastening anchor into the bundle receptacle bore, as a result of which the at least one end-proximal anchoring structure can then be formed on the fastening anchor. In this context, it can be expedient when the fastening anchor is incorporated into the bundle receptacle bore in an alignment in which said fastening anchor meets the bundle receptacle bore by way of an identical projection beyond a periphery of the bundle receptacle bore on both sides. This can facilitate a symmetrical deformation of the fastening anchor during incorporation into the bundle receptacle bore.

The fastening anchor can be incorporated into the bundle receptacle bore by a thruster tongue of a stuffing tool of a bristle product manufacturing machine, wherein the thruster tongue has on its front end a width larger than a diameter of the bundle receptacle bore.

The use of a thruster tongue designed in such a manner enables the abovementioned displacement of material of the bristle carrier from the peripheral region of the bundle receptacle bore into the bundle receptacle bore and over the fastening anchor.

During incorporation of the fastening anchor the thruster tongue can peel material of the bristle carrier from the peripheral region of the bundle receptacle bore and displace said material into the bundle receptacle bore in order to also fix the fastening anchor in the bundle receptacle bore in a form-fitting manner.

The fastening anchor and/or the bristle carrier are/is preferably composed of plastics material, particularly preferably having a content of recycled plastics material. This facilitates an environmentally friendly manufacturing of bristle products, and a positive utilization of plastics material as a resource. Moreover, such a bristle product can be recycled to an ideally great extent and in a simple manner.

The fastening anchor can be composed of a plastics material which is softer than a plastics material of which the bristle carrier is composed. This facilitates a clean forming of the fastening anchor while forming at least one anchoring structure, and an intact bundle receptacle bore in the bristle carrier.

The fastening anchor can also be composed of a plastics material which is harder than a plastics material of which the bristle carrier is composed. This facilitates an additional penetration of the fastening anchor into the bristle carrier and, as a result, a form-fitting connection between the fastening anchor and the bristle carrier.

The form-fitting connection between the fastening anchor and the bristle carrier can be facilitated when the fastening anchor and the bristle carrier are composed of plastics materials of the same plastics material family, or of the same plastics material.

A fastening anchor and/or a bristle carrier which are/is composed of a plastics material having a hardness of at least 60 Shore D, 70 Shore D, or particularly preferably of at least 80 Shore D, can be used for carrying out the method. As an upper limit, the plastics material can have a hardness of 100 Shore D, for example.

A materially integral connection between the fastening anchor and the bristle carrier can likewise be facilitated when the bristle carrier and the fastening anchor are composed of a plastics material having a comparable, preferably an identical, hardness.

Providing the bristle carrier can be simplified when the at least one bundle receptacle bore of the bristle carrier is designed to be free of an anchor track. In comparison to concepts previously known from practice, in which the bundle receptacle bores have a predefined anchor track for the fastening anchor so as to simplify positioning of the fastening anchor in the material of the bristle carrier, an anchor track of this type can be dispensed with in the proposed method. Instead, a bundle receptacle bore which is free of an anchor track can facilitate a defined deformation of a bristle bundle while forming at least one anchoring structure, and be advantageous in this context.

The bundle receptacle bore used when carrying out the method can have a bore wall which is at least in portions cylindrical, and/or a conical bore wall tapering toward the bore base, and/or a stepped bore wall and/or a bore wall having a retaining structure, for example latching lines. In one embodiment of the bristle carrier, a cone angle of a conical portion of a bore wall, which tapers toward the bore base, can be, for example, at most 7°, so as not to compromise a reliable fixing of the bristle bundle and of the fastening anchor in the bundle receptacle bore.

In order to be able to implement the desired extraction forces which the bristle bundles and the fastening anchors are to withstand during use of the bristle product, in particular when the latter is designed as a toothbrush, it can be advantageous when the plastics material of the bristle carrier and/or of the fastening anchor has an E modulus of at least 1000 MPa (megapascal) or 2000 MPa, in particular an E modulus which is between 1000 MPa or 2000 MPa and 10,000 MPa.

The fastening anchor can be anchored in the bundle receptacle bore in a particularly reliable manner when the plastics material of which the bristle carrier and the fastening anchor is composed, has a tensile strength of at least 30 MPa or of at least 45 MPa. The plastics material preferably has a tensile strength between 30 MPa or 45 MPa and 110 MPa.

The use of the following plastics material has proven to be particularly suitable: polyamide 12 (PA12), polyamide 6 (PA6), polyamide 6.12 (PA6.12), polystyrene (PS), polybutylene terephthalate (PBT), polycarbonate (PC), polyoxymethylene (POM), styrene acrylonitrile resin (SAN), acrylonitrile, polyethylene terephthalate (PE), or polypropylene (PP), in particular fiber-reinforced polypropylene.

In a preferred embodiment of the bristle product, the bristle carrier and the at least one fastening anchor are composed of polybutylene terephthalate (PBT). PBT can have a tensile strength of 60 MPa and an E modulus of 2500 MPa. Due to the relatively high tensile strength and the likewise relatively high E modulus of PBT, extraction forces which the anchoring of the bristle bundles in the bristle carrier withstands can be achieved in the range between 10 N and 30 N using fastening anchors of PBT to anchor bristle bundles of PBT in bristle carriers of PBT.

As has already been indicated above, the fastening anchor and the bristle bundle can be incorporated into the bundle receptacle bore of the offered-up bristle carrier, in particularly stuffed into the latter, by a stuffing tool of a bristle product manufacturing machine. This enables the fully automated manufacturing of bristle products.

The fastening anchor used when carrying out the method can be profiled, i.e. have a cross section deviating from a rectangular cross section. The profiling of the fastening anchor can facilitate the forming of the anchoring structure according to the invention on at least one end of the fastening anchor.

The fastening anchor can be cut to length from a, for example profiled, anchor strip by means of an anchor cutting device, and be supplied to the stuffing tool of the bristle product manufacturing machine. The anchor strip can be unwound from an anchor spool and supplied to the anchor cutting device. For example, the supply of the anchor strip from the strip spool can take place in a force-and/or impulse-decoupled manner. The anchor strip can be supplied to the anchor cutting device from a strip buffer in which a portion of the anchor strip is kept ready without tension. The strip buffer herein can be disposed between the strip spool and the anchor cutting device.

For fixing the bristle bundles and the fastening anchors in bundle receptacle bores of bristle carriers of bristle products to be manufactured, the bristle bundles and the fastening anchors can be stuffed into the bundle receptacle bores at a stuffing rate of at least 400 stuffing procedures per minute, or of at least 600, 800, 1000 or 1200 stuffing procedures per minute. This enables particularly efficient manufacture of bristle products. An upper limit of the stuffing rate can be, for example, 1500 or 2000 stuffing procedures per minute.

A thruster tongue by which the bristle bundle and the fastening anchor are incorporated into the bundle receptacle bore can strike the bundle receptacle bore at a speed between 1.2 m/s and 4.0 m/s, preferably between 1.8 m/s and 3.5 m/s, particularly preferably between 2.2 m/s and 2.8 m/s. It is ensured in these speed ranges that a sufficient amount of kinetic energy acts on the fastening anchor for the targeted deformation of the fastening anchor and for forming at least one end-proximal anchoring structure, when said fastening anchor is incorporated into the bundle receptacle bore.

Proposed for achieving the object is also a bristle product manufacturing machine which is specified for carrying out the method for manufacturing a bristle product having one or more of the features disclosed herein.

For this purpose, the bristle product manufacturing machine can have a stuffing tool which comprises a thruster tongue for incorporating bristle bundles and fastening anchors into bundle receptacle bores of offered-up bristle carriers.

The thruster tongue can have at least one peeling edge which is formed on a narrow side of a front end of the thruster tongue. The front end of the thruster tongue is the side by way of which the thruster tongue incorporates fastening anchors conjointly with bristle bundles into bundle receptacle bores, and in the process plunges into the bundle receptacle bores. With the aid of the at least one peeling edge it is possible to peel material of a bristle carrier from the peripheral region of the bundle receptacle bores, and during incorporation of the fastening anchor to displace said material into the bundle receptacle bores so as to also fix the fastening anchors in a form-fitting manner in the bundle receptacle bores. Preferably, the thruster tongue has in each case at least one peeling edge on each of two sides of its front end that face away from one another. In this way, material can be displaced from two sides into the bundle receptacle bores. This facilitates a particularly reliable, form-fitting fixing of the deformed fastening anchors in the bundle receptacle bores.

In this context, it can be advantageous when a spacing between the two narrow sides of the front end of the thruster tongue is larger than a bore diameter of the bundle receptacle bores which are to be stuffed with bristle bundles and fastening anchors with the aid of the thruster tongue.

In one embodiment of the bristle product manufacturing machine, the thruster tongue has on its front end, preferably adjacent to a narrow side of the front end, at least one clearance having at least one material-guiding face. It is then possible to displace peeled material of the bristle carrier in the direction of the bundle receptacle bore by way of the material-guiding face and, as a result, to fix the fastening anchors in a form-fitting manner within the bundle receptacle bores.