EP2552276B1 - Method for connecting bristle supports having bristles to cover parts during brush production - Google Patents

Description

The invention relates generally to a method of making brushes, and more particularly to a method of bonding bristled bristle carriers to cover members in the manufacture of brushes, particularly toothbrushes.

Various methods of making brushes are known. Conventionally, a brush body is provided with an array of holes ("hole pattern") corresponding to the desired arrangement of bristles. Bundles or tufts of bristles are then inserted into the holes of the brush body and anchored therein by means of impressed small metallic anchors or by means of loops.

In an alternative method of making brushes that has become established in just a few years and is referred to as Anchor Free Tufting (AFT), the bristle tufts are attached to a small brush head plate without the use of loops or anchors. and the carrier plate is then inserted into or attached to a brush body or handle. In a variant of the AFT method brush handles are made with a hole pattern that corresponds to the desired tuft pattern. Bristle tufts are then inserted into these holes and attached to the brush handles. The attachment ends of the tufts are then covered with a small plate, which in turn is attached to the brush handle.

In the AFT method brush elements of any type and shape can be mounted in the holes of the top plate or the brush body: bristles or bristle bundles of thermoplastic material, cleaning elements made of elastomeric material, which are formed for example by injection molding, or natural fibers. The brush elements of the bristled head plates or brush body can be contoured and - in the case of Bristle bundles - already rounded at the free ends. But it is also possible to produce any contouring or rounding in a subsequent processing step.

To attach the top plate to a brush body, it is known to insert the top plate in a recess in the handle and to weld the two parts by means of ultrasound. This is a fast and reliable way to join the parts. The disadvantage of this method is that a gap or a cavity between the back of the top plate and the end face of the recess remains in the brush body. It can not be ruled out that contaminations that are detrimental to hygiene can be found in these gaps.

From the WO 2011/072865 A1 , which is a post-published prior art, a method for producing a brush is known, in which a bristle carrier made of thermoplastic material with through holes and a peripheral edge surrounding these holes is made. In the holes of the bristle carrier brush elements are attached. A cover part in the form of a brush body made of thermoplastic material with a mounting area for the bristle carrier and with sacrificial structures formed in the mounting area as well as a connecting edge surrounding the mounting area is likewise provided. The peripheral edge, sacrificial structures and connecting edge are plasticized by heating and welded together. Plasticized mass of the sacrificial structures can flow into the volume bordered by the connecting edge of the covering part and lying between the bristle carrier and the covering part.

Furthermore, from the EP 1 839 538 A2 a method for making a brush is known in which the bristle carrier and the cover part are welded together at their opposite surfaces. For this purpose, integrally formed, to be melted projections are provided.

The invention makes it possible to bring together bristle carrier and cover without intervening gaps or voids quickly and safely with each other.

According to the invention, first, a bristle carrier made of thermoplastic material with through holes and a surrounding these holes Peripheral edge made. The bristle carrier may be a top plate or a brush handle. In the holes of the bristle carrier brush elements such as bristles, bristle bundles, cleaning elements made of elastomer material and natural fibers are then attached. Furthermore, a cover part is formed and provided as part of a brush body of thermoplastic material with a mounting area for the bristle carrier and with sacrificial structures formed in the mounting area and a connection edge surrounding the mounting area. The surrounding the holes peripheral edge of the bristle carrier and the sacrificial structures of the cover and its connection edge are then plasticized by heating. Preferably, the outer surfaces of the cover and the bristle carrier are excluded from the plasticization, since they are a part of the brush body and should not be deformed by heating. This exclusion can be done by means of heat shields with which radiation heat is held. Then bristle carrier and cover are pressed against each other, the following happens: The plasticized peripheral edge of the bristle carrier is welded to the plasticized connection edge of the cover. But excluded from the plasticization outer surfaces of the cover and the bristle carrier remain in shape. The plasticized mass of the sacrificial structures then flows into the volume bordered by the connecting edge of the covering part, remaining between the bristle carrier and the covering part, and at least largely fills this volume. Thus, the retention of gaps or voids between bristle carrier and cover is avoided.

The sacrificial structures can be formed in many forms. Advantageously, they are designed as fine ribs, tines or blocks, which rise from the bottom of the mounting portion of the cover. In this form, the sacrificial structures can be well controlled eg plasticized without contact by radiation heat for the welding process. The ribs may be formed as fine longitudinal ribs and / or transverse ribs, or as surrounding and spaced apart rings. Other advantageous embodiments are blocks that have cross-shaped, star-shaped or annular cross-sections. Another alternative is sacrificial structures in the form of a plateau rising from the bottom of the mounting area of the cover part or several such plateau areas. In any case, the Sacrificial structures dimensioned so that their plasticized mass fills the remaining between bristle carrier and cover volume.

Depending on the type and shape of the brush to be produced, either the bristle carrier is a top plate and the cover part is formed on a brush handle or brush handle, or conversely, the brush head is directly brushed, wherein the cover member is formed as a cover plate completing the brush body. In the latter embodiment, the brush head may then be shaped as a small round disc and the cover plate provided with a pin for coupling to a drive mechanism, as required for the so-called electric toothbrushes.

• Figur 1 eine auseinandergezogene Perspektivansicht eines beborsteten Borstenträgerplättchens und eines Bürstenstiels vor dem Zusammenbau;
• Figur 2 eine schematische Schnittansicht zur Veranschaulichung eines Verfahrensschritts, bei dem thermoplastische Kunststoffteile zur Verschweißung miteinander plastifiziert werden;
• Figur 3 eine Perspektiv-Teilansicht einer fertiggestellten Zahnbürste;
• Figur 4 einen Querschnitt durch den Kopfbereich der Zahnbürste nach Figur 3;
• Figur 5 bis Figur 10 Varianten verschiedener Ausführungsformen von Befestigungsbereichen am Bürstenkopf mit plastifizierbaren Opferstrukturen;
• Figur 11 eine auseinandergezogene Perspektivansicht eines kreisrunden Borstenträgerplättchens und seiner Abdeckung vor dem Zusammenbau;
• Figur 12 eine Perspektivansicht der aus den in Figur 11 gezeigten Teilen zusammengesetzten Bürste;
• Figur 13 eine weitere Variante eines Bürstenstiels mit einem tiefgesetzten Kopfbefestigungsbereich und darin angebrachten plastifizierbaren Opferstrukturen;
• Figur 14 eine auseinandergezogene Perspektivansicht eines beborsteten Borstenträgerplättchens und eines Bürstenstiels vor dem Zusammenbau in einer weiteren Ausführungsform;
• Fig. 14a einen Teilschnitt des Bürstenstiels mit aufgesetztem Hitzeschild;
• Fig. 14b einen Teilschnitt des Borstenträgerplättchens mit aufgesetztem Hitzeschild;
• Fig. 14c einen Teilschnitt des Verbindungsbereiches zwischen Bürstenstiel und Borstenträgerplättchen;
• Figur 15 eine auseinandergezogene Perspektivansicht eines beborsteten Borstenträgerplättchens und eines Bürstenstiels vor dem Zusammenbau in einer weiteren Ausführungsform;
• Fig. 15a einen Teilschnitt des Borstenträgerplättchens mit aufgesetztem Hitzeschild;
• Fig. 15b einen Teilschnitt des Bürstenstiels mit aufgesetztem Hitzeschild;
• Fig. 15c einen Teilschnitt des Borstenträgerplättchens mit aufgesetztem Hitzeschild gemäß einer Variante;
• Fig. 15d einen Teilschnitt des Verbindungsbereiches zwischen Bürstenstiel und Borstenträgerplättchen bei der Variante gemäß Fig. 15a oder 15c;
• Fig. 15e einen Teilschnitt des Borstenträgerplättchens mit aufgesetztem Hitzeschild gemäß einer weiteren Variante;
• Fig. 15f einen Teilschnitt des Verbindungsbereiches zwischen Bürstenstiel und Borstenträgerplättchen bei der Variante gemäß Fig. 15e;
• Figur 16 eine auseinandergezogene Perspektivansicht eines beborsteten Borstenträgerplättchens und eines Bürstenstiels vor dem Zusammenbau in einer weiteren Ausführungsform;
• Fig. 16a einen Teilschnitt des Bürstenstiels mit aufgesetztem Hitzeschild;
• Fig. 16b einen Teilschnitt des Borstenträgerplättchens mit aufgesetztem Hitzeschild;
• Fig. 16c einen Teilschnitt des Verbindungsbereiches zwischen Bürstenstiel und Borstenträgerplättchen;
• Fig. 16d einen Teilschnitt des Borstenträgerplättchens mit aufgesetztem Hitzeschild gemäß einer weiteren Variante;
• Fig. 16e einen Teilschnitt des Verbindungsbereiches zwischen Bürstenstiel und Borstenträgerplättchen bei der Variante gemäß Fig. 16d;
• Figur 17 a einen Teilschnitt mit am Umfangsrand des Borstenträgerplättchens angebrachten Schweißhilfen in Form von feinen Vorsprüngen;
• Fig. 17 b eine Variante der Schweißhilfe; und
• Fig. 17 c eine weitere Variante der Schweißhilfe.

Further features and advantages of the invention will become apparent from the following description of several embodiments with reference to the accompanying drawings. In the drawings show:

• FIG. 1 an exploded perspective view of a bristled bristle carrier plate and a brush handle before assembly;
• FIG. 2 a schematic sectional view illustrating a process step in which thermoplastic plastic parts are plasticized for welding together;
• FIG. 3 a partial perspective view of a finished toothbrush;
• FIG. 4 a cross section through the head portion of the toothbrush after FIG. 3 ;
• FIG. 5 to FIG. 10 Variants of various embodiments of attachment areas on the brush head with plastifiable sacrificial structures;
• FIG. 11 an exploded perspective view of a circular bristle carrier plate and its cover before assembly;
• FIG. 12 a perspective view of the in FIG. 11 parts shown assembled brush;
• FIG. 13 a further variant of a brush handle with a lowered Kopfbefestigungsbereich and mounted therein plastifiable sacrificial structures;
• FIG. 14 an exploded perspective view of a bristled bristle carrier plate and a brush handle before assembly in another embodiment;
• Fig. 14a a partial section of the brush handle with attached heat shield;
• Fig. 14b a partial section of the bristle carrier plate with attached heat shield;
• Fig. 14c a partial section of the connecting portion between the brush handle and bristle carrier platelets;
• FIG. 15 an exploded perspective view of a bristled bristle carrier plate and a brush handle before assembly in another embodiment;
• Fig. 15a a partial section of the bristle carrier plate with attached heat shield;
• Fig. 15b a partial section of the brush handle with attached heat shield;
• Fig. 15c a partial section of the bristle carrier plate with attached heat shield according to a variant;
• Fig. 15d a partial section of the connecting portion between the brush handle and bristle carrier plate in the variant according to Fig. 15a or 15c ;
• Fig. 15e a partial section of the bristle carrier plate with attached heat shield according to another variant;
• Fig. 15f a partial section of the connecting portion between the brush handle and bristle carrier plate in the variant according to Fig. 15e ;
• FIG. 16 an exploded perspective view of a bristled bristle carrier plate and a brush handle before assembly in another embodiment;
• Fig. 16a a partial section of the brush handle with attached heat shield;
• Fig. 16b a partial section of the bristle carrier plate with attached heat shield;
• Fig. 16c a partial section of the connecting portion between the brush handle and bristle carrier platelets;
• Fig. 16d a partial section of the bristle carrier plate with attached heat shield according to another variant;
• Fig. 16e a partial section of the connecting portion between the brush handle and bristle carrier plate in the variant according to Fig. 16d ;
• FIG. 17 a partial section with attached at the peripheral edge of the bristle carrier plate welding aids in the form of fine protrusions;
• Fig. 17b a variant of the welding aid; and
• Fig. 17 c another variant of the welding aid.

The embodiments of the method described below relate to the production of toothbrushes. However, the same principles are applicable to the production of different types of brushes.

In FIG. 1 are shown by a toothbrush handle of the brush neck 10 and the head part 12, the latter with a mounting portion 14 for a ready-bristled bristle carrier in the form of a bristle carrier plate 16. The bristle carrier plate 16 is equipped with differently shaped and profiled bristle bundles, preferably with the aforementioned AFT Procedures are attached. However, depending on the type of bristles or brush elements, other fastening methods are possible, for example the injection molding of elastomeric parts or the gluing of natural fibers.

The mounting portion 14 of the head portion 12, also called cover member is provided with sacrificial structures in the form of annular fine ribs surrounding each other, which rise from the bottom of the mounting portion. They are surrounded by the outer peripheral edge 12a of the head part. The shape of the sacrificial structures is highly variable and determined by the process parameters of the chosen attachment method. The sacrificial structures 18 provide, on the one hand, the material for the welding to the bristle carrier plate 16 and, on the other hand, the necessary mass in order to completely fill the space present between the head part 12 and the bristle carrier plate 16.

In FIG. 2 For the sake of simplification, it is assumed that the sacrificial structures 18 rising from the bottom of the attachment area are small blocks. The bristled bristle carrier plate 16 consists of the head plate 20 and the bristle tufts 22 anchored thereto, which are fused on the back of the head plate 20 and optionally form a continuous fused layer. Between the back of the head plate 20 and the mounting portion of the head portion 12, a heater is introduced, which is symbolically represented here as an electric heating coil 24. This heater 24 preferably heats the peripheral edge 20a of the head plate 20 as shown in FIG FIG. 2 illustrated by small arrows, and on the opposite side of the sacrificial structures 18 and the peripheral edge 12 a of the head part 12 formed connecting edge 12 b. By contrast, the outer region 12c of the head part surrounding this connection edge 12b remains uncovered by the heating. By means of the heating device 24, the thermoplastic material constituting the head plate 20 and the brush handle with the sacrificial structures 18 is plasticized in a well-controlled manner, whereupon the heater 24 is removed and the parts are pressed together to weld them together. FIG. 3 shows the finished brush head. Out FIG. 4 It can be seen that between the back of the bristle carrier plate 16 and the head part 12 no dead volume remains because the sacrificial structures have penetrated in the plasticized state and under pressure in all cavities and have filled them. In FIG. 4 it can also be seen that the connecting edge of the head part 12 is welded to the peripheral edge of the bristle carrier plate 16, but while the outer surface of the head part 12 is intact and preserved in shape.

The in the FIGS. 5 to 10 shown variants of sacrificial structures are particular embodiments, each of which has particular advantages for the applied connection method, in terms of Plastifizierbarkeit, the flow behavior in welding and compression and in the ability to fill all cavities as completely as possible.

at FIG. 5 the sacrificial structures are again executed as fine ribs surrounding each other in a ring, but in lesser numbers than at FIG. 1 , and at the bottom of the attachment area, steps 18a are formed which surround the annular ribs 18.

at FIG. 6 The fine ribs extend parallel to each other in the longitudinal direction. at FIG. 7 they also extend parallel to each other, but in the transverse direction.

at FIG. 8 the sacrificial structures are formed as fine blocks, which are cross-shaped in cross section. Also at FIG. 9 the sacrificial structures are small blocks, but here they are circular in cross section.

As FIG. 10 shows, it is also possible to arrange at the bottom of the attachment area an upstanding plateau, which can pass in one piece or is also divided several times. The height of the plateau above the bottom of the attachment area depends on the geometry of the parts to be joined. Plate-shaped sacrificial structures tend to be plasticized to a lesser depth when exposed to heat, which may be advantageous for very flat header plates.

The FIG. 11 shows an embodiment in which the bristled bristle carrier 30 is part of a round brush body, as used in so-called electric toothbrushes. As a cover acts here a cover plate 32, which is also designed round and has on its bristle carrier 30 side facing a mounting area with molded sacrificial structures 18 in the form of concentric annular fine ribs. The cover plate 32 is provided on its side facing away from the bristle carrier back with a pin 34 which is intended for coupling to a drive mechanism. Also at the in FIG. 11 In the embodiment shown, the parts are analogous to those in FIG FIG. 2 illustrated method welded; The result is in FIG. 12 shown.

A variant of the in the FIGS. 1 to 4 shown embodiment is that as shown in FIG FIG. 13 the head part 12 is offset from the brush neck 10 by a step 13. The sacrificial structures 18 are similar to those in FIG FIG. 5 educated. In this embodiment, the bristle carrier plate has a correspondingly greater thickness.

In Fig. 14 illustrates how the selective plasticization of the areas to be welded and the sacrificial structures can be carried out in the practice of the method. In the embodiment shown The flat peripheral edge 20a of the bristle carrier plate and the also flat connection edge 12b of the brush handle are welded. According to Fig. 14a When heated by heat radiation surrounding the outer edge of the brush handle 12 surrounding the surface to be plasticized with a correspondingly shaped heat shield 30. Likewise, according to Fig. 14b the non-plasticizing outer surface of the bristle carrier plate, namely the side surface and the outer edge of the front surface, covered with a suitably shaped heat shield 32. The result after compressing the parts is in Fig. 14c shown. The welded joint is indicated by an arrow "S". The sacrificial structures form a melt 18a, which fills the gap of the connected parts.

Depending on the material properties of the brush elements 22, welding with the melt of these brush elements can also take place.

The FIGS. 15 and 16 show further variants of the welded joint between brush handle 12 and bristle carrier plate 20th

at Fig. 15 the brush handle 12 has a step 23 in the region of the holder for the bristle carrier plate Fig. 15a or 15c the bristle carrier plate should be welded both on the flat peripheral edge and on the side surface. Accordingly, with the heat shield 32 only the edge of the front ( Fig. 15a ) or this edge and a small part of the side surface ( Fig. 15c ) of the bristle carrier plate 20. Further, with the heat shield 30 which is adjacent to the step 23 outer surface of the brush handle 12 is covered. The result after compressing the parts shows Fig. 15d , Small arrows in the figure point to the welded surfaces. However, if the side surface of the bristle carrier plate 20 is to be excluded from the welding, the heat shield 32 also covers the side surface, as in FIG Fig. 15e shown; the result is in Fig. 15f shown.

In Fig. 16 The bristle carrier plate 20 has an angled peripheral edge whose end face forms a connecting edge 20c. The corresponding connection edge 12b of the brush handle is at the peripheral edge of the sacrificial structures 18. As in FIG Fig. 16a is shown with the heat shield 30 surrounding the connection edge 12b outer surface of the Brush handle 12 covered. If also the side surface of the bristle carrier plate 20 to be welded, is covered with the heat shield 32, only the edge of the front, as in Fig. 16b shown. Fig. 16c shows the result after compressing the parts. Small arrows in Fig. 16c show on the welded surfaces. But if the side surface of the bristle carrier plate 20 is not to be welded, this is covered with the heat shield 32, as in Fig. 16d shown with the in Fig. 16e shown result.

Further developments to facilitate the welding process are in Fig. 17 shown. In Fig. 17a are formed on the surfaces to be welded at the peripheral edge of the bristle carrier plate 20 fine tine-shaped projections or elevations, which are plasticized particularly quickly when heated by radiation. According to Fig. 17b For example, these projections 40 may be limited to the flat peripheral edge of the bristle carrier plate 20. According to Fig. 17c Both the protrusions 40 are provided on the flat peripheral edge of the bristle carrier plate 20 and corresponding projections 42 on the connecting edge of the bristle stem 12.

Preferably, the non-plasticized peripheral edge 12a has a greater thickness than the sacrificial structures measured in plan view.

The thickness of the non-plasticized peripheral edge 12 a is also viewed in plan view also a maximum of 1.5 mm, preferably 0.5 to 1 mm.

As the maximum thickness for the sacrificial structure, a maximum thickness of 1.5 mm has been found, the thickness is preferably only 0.5 to 1 mm.

Claims (13)

1. A method of manufacturing a brush, comprising the following steps:

   (a) manufacturing a bristle carrier from a thermoplastic material with through-holes and a circumferential edge (20a) surrounding these holes;

   (b) fastening brush elements such as bristles, bundles of bristles, cleaning elements made from an elastomeric material, and natural fibers in the holes of the bristle carrier;

   (c) forming a cover part as a component of a brush body from a thermoplastic material with a mounting area for the bristle carrier and with sacrificial structures (18) integrally molded in the mounting area and a connecting edge (12b) surrounding the mounting area;

   (d) plasticizing the circumferential edge (20a) of the bristle carrier, the sacrificial structures (18) of the cover part, and the connecting edge (12b) of the cover part by heating;

   (e) pressing the bristle carrier and the cover part against each other, wherein

   - the plasticized circumferential edge (20a) of the bristle carrier is welded to the plasticized connecting edge (12b) of the cover part;

   - the outer surface, excluded from the plasticizing, of the cover part retains its shape; and

   - the plasticized mass of the sacrificial structures flows into the volume bordered by the connecting edge (12b) of the cover part and remaining between the bristle carrier and the cover part, and at least largely fills this volume.
2. The method according to claim 1, in which the sacrificial structures (18) are formed as fine ribs, tines or small blocks which protrude upwards from the bottom of the mounting area of the cover part.
3. The method according to claim 2, in which the ribs are formed as fine longitudinal ribs and/or transverse ribs.
4. The method according to claim 2, in which the ribs are formed as rings that surround one another and are spaced away from one another.
5. The method according to claim 2, in which the small blocks have cross-shaped, star-shaped or ring-shaped cross-sections.
6. The method according to claim 1, in which the sacrificial structures (18) are formed as a plateau protruding upwards from the bottom of the mounting area of the cover part or as a plurality of such plateau areas.
7. The method according to any of the preceding claims, in which the sacrificial structures (18) are dimensioned such that their plasticized mass fills the volume remaining between the bristle carrier and the cover part.
8. The method according to any of the preceding claims, in which the cover part is formed on the brush body itself and the bristle carrier defines a head plate or a bristle carrier platelet (16).
9. The method according to any of claims 1 to 7, in which the bristle carrier is formed as a brush handle, and the cover part is formed as a cover platelet which completes the brush body.
10. The method according to any of claims 1 to 7, in which the bristle carrier is formed as a part of a round brush body, and the cover part is formed as a cover platelet which completes the brush body and is provided with a pin for coupling to a drive mechanism.
11. The method according to any of claims 1 to 10, in which outer surfaces of the cover part and/or of the bristle carrier are excluded from the plasticizing.
12. The method according to any of claims 1 to 10, in which outer surfaces of the cover part and/or of the bristle carrier are excluded from the plasticizing by shielding by means of a heat shield.
13. The method according to any of claims 1 to 12, in which connecting surfaces, to be welded to each other, of the cover part and of the bristle carrier are provided with fine projections which are preferentially plasticized when heated.

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