Toothbrushes have long been manufactured using a process known as "staple tufting". Staple tufting involves providing a bundle of filaments having a length that is approximately twice as long as the desired bristle length, folding the bundle in half to form a bristle tuft, and securing the tuft in place in a pre-cored hole in the head of the toothbrush by inserting the tuft into the pre-cored hole with a metal staple.

As alternatives to this process, other tufting processes have been proposed that involve forming a bristle tuft and then injection molding a toothbrush head around the formed tuft. Typically, after the toothbrush is molded it is then necessary to trim and/or end-round the tips of the bristles to form a finished toothbrush.

The invention features a method of and a device for bristle tufting in which the bristles are molded into a brush head. Advantageously, the method and device of the invention eliminate the need to trim and/or end-round the bristle tips after molding. The method and device of the invention also allow the contour defined by the bristle tips to be easily selected and a desired contour obtained.

In one aspect, the invention features a method of bristle tufting that includes providing a plurality of bristles, each bristle having a first, end-rounded end and a second end; grouping the end-rounded bristles into tufts; fusing the second ends of the bristles in each tuft together ; and forming a brush head around the fused second ends. Preferably, the forming step includes inserting the second ends of the bristle tufts into a molding cavity of a molding device and filling the molding device with a molding material.

In preferred embodiments, the grouping step includes inserting the second ends of the tufts into apertures in a molding insert, and the forming step includes placing the molding insert in a molding device, and filling the molding device with a molding material to form a brush head surrounding the fused ends of the tufts. Preferably, the method further includes, after the grouping step and before

the fusing step, pushing the second ends through the apertures in the insert and positioning the second ends of each tuft a predetermined distance beyond the surface of the insert opposite the surface facing the first ends of the bristles, and selecting the predetermined distance so that the portion of each tuft that remains on the side of the insert facing the first ends of the bristles has a length that is substantially equal to the desired bristle length of that tuft. The method further includes varying the predetermined distance for each tuft, depending on the position that the tuft will have on the brush head, to cause the first ends of the bristles to define a contoured brushing surface. The molding cavity is constructed to receive sufficient molding material during the filling step to form a finished oral brush.

In another aspect, the invention features a bristle tufting device for applying a bristle tuft to a brush, e. g., an oral brush. The bristle tufting device includes a bristle transferring device, a tuft fusing device, and a brush head forming device. The bristle transferring device includes (a) a magazine constructed to hold a plurality of bristles positioned with their longitudinal axes substantially parallel, (b) a hollow bristle transfer member constructed to receive a group of bristles, (c) an elongate plunger constructed to push said group of bristles a predetermined distance out of said bristle transfer member, and (d) an insert having an aperture constructed to receive the group of bristles. The tuft fusing device includes a heating device constructed to heat the ends of the bristles that are pushed out of the insert by the plunger. The heating device is constructed to fuse the bristles of each tuft together without fusing the tufts together, or the heating device is constructed to fuse the second ends of the bristles together and also to fuse the tufts together. The brush head forming device includes a molding device having a molding cavity constructed to receive the insert in sealing engagement and to receive a sufficient quantity of molding material to surround the fused tuft ends and to form a brush head.

Preferred bristle tufting devices include one or more of the following features. The device includes a plurality of hollow transfer members and elongate plungers, each hollow transfer member being associated with a corresponding elongate plunger, and the insert includes a plurality of apertures, each aperture being constructed to receive a group of bristles transferred by a corresponding hollow transfer member. The device includes a transfer carriage constructed to transfer the

insert from a position in which bristle ends extending from the insert are heated by the heating device to a position in which the insert defines a portion of the molding cavity. The molding cavity is constructed to receive molding material that will form a complete oral brush.

In yet another aspect, the invention features a system for manufacturing an oral brush. The system includes, in sequence, an end-rounding and trimming device, and a bristle tufting device that includes a bristle transferring device, a tuft fusing device, and a brush head forming device.

Preferred manufacturing systems include one or more of the following features. The bristle tufting device includes the preferred features discussed above. The end-rounding and trimming device is preferably a device as described in co-pending U. S. Serial No., filed on even date and titled "Method and Device for Trimming and End-Rounding Bristles", the disclosure of which is incorporated herein by reference. The end-rounded bristles are formed by providing continuous filaments of bristle stock, gathering the filaments together to form a group of filaments arranged so that the longitudinal axis of each filament is substantially parallel to the longitudinal axes of the other filaments and the ends of the filaments define a plane, end-rounding the ends of the filaments as they are held in the group, and cutting off a length of the grouped filaments to define a cut bundle. The system further includes a brush cooling device to cool the brushes as they exit the molding cavity.

The invention further features a method of forming a brush having a contoured brushing surface. The method includes: (a) providing a plurality of bristles; (b) grouping the bristles into tufts, each tuft having a first end and a second end; (c) positioning the first ends of the tufts to define the desired contoured brushing surface; (d) fusing the second ends of the tufts to hold the bristles of each tuft together; and (e) forming a brush head surrounding the fused second ends of the tufts.

The invention also features methods of using the devices of the invention to apply bristle tufts to a brush.

The term"oral brush", as used herein, refers to any type of brush, suitable for use in the mouth, which can be produced by the methods or using the

devices of the invention, i. e., a brush that includes fusable bristle ends and a molded head.

Other features and advantages of the invention will be apparent from the description of preferred embodiments thereof, taken together with the drawings, and from the claims.

Fig. 1 is a schematic top view of a system for manufacturing oral brushes.

Fig. 2 is a schematic side view of a bristle tufting machine suitable for use in the system of Fig. 1.

Figs. 3-3f are schematic side views of the upper portion of the bristle tufting machine of Fig. 2 in different positions, showing the sequence of operation of this portion of the machine.

Figs. 4-4c are schematic side views of the lower portion of the bristle tufting machine in different positions, showing the sequence of operation of this portion of the machine.

Figs. 5 and 5a are schematic side views of the lowermost portion of the bristle tufting machine in different positions, corresponding to the right and left positions shown in Figs. 3-3f and 4-4c.

Fig. 6 is a schematic top view, and Fig. 6a a schematic side cross-sectional view, of an insert according to one embodiment of the invention.

Fig. 7 is a highly enlarged schematic side view of fused tuft of bristles in an insert, according to one embodiment of the invention. Fig. 7a shows the positioning of the insert of Fig. 7 in a mold tool of a molding machine. Fig. 7b is a highly enlarged cross-sectional view of a portion of a brush head, showing the positioning of a bristle tuft in the molded brush head.

Fig. 8 is a highly enlarged schematic side view of a plurality of groups of bristles being pushed through an insert, the individual groups being pushed through to different extents to form a contoured brushing surface.

Referring to Fig. 1, a preferred oral brush manufacturing system 10 includes a plurality of end-rounding/trimming machines 12, arranged in parallel, a buffer/transfer zone 14 for each end-rounding/trimming machine in which end-rounded, trimmed bristles are transferred to a fiber box type buffer on the

tufting machine, and a plurality of bristle tufting machines (brush machines) 16 positioned to receive end-rounded bristles from buffer/transfer zone 14 and form the bristles into tufts as will be described below. When the bristles have been formed into tufts, they are transferred to an insert molding machine 18, in which molding material is injection molded around the base of the tufts to form an oral brush.

Each oral brush is then cooled on a cooling conveyor 22. The finished oral brushes can then be packaged in any desired manner, e. g., in blister pack packaging.

A preferred bristle tufting machine 24 for use in the above method is shown in Fig. 2, and portions of the machine are shown in the different positions of the machine in Figs. 3-5a.

Bristle tufting machine 24 includes a stationary floor plate 26, on which a bristle magazine 28 is mounted. Bristle magazine 28 contains a plurality of bristles. The bristles are preferably end-rounded, and, if this is the case, their end-rounded tips are positioned facing downward. The bristles begin the tufting process in the bristle magazine 28, and are subsequently transferred from the bristle magazine 28 to an insert 32 (shown in detail in Fig. 6) for tufting, as will be explained further below. Floor plate 26 also includes, on each side of the bristle magazine 28, an array of apertures 30. Insert 32 is placed over one of the arrays of apertures, and apertures 34 in insert 32 (discussed below) are aligned with apertures 30 so that bristle tufts can be inserted and guided through the floor plate into and through apertures 34 in the insert, as will be explained below. To align the insert with the array of apertures in this manner, an alignment device is provided, e. g., alignment dowels 31 on the floor plate which are inserted through alignment holes 33 on the insert, as shown in Fig. 6. Other alignment devices may be used, as is well known in the art; for example, the dowels could be provided on the insert and the holes on the floor plate.

As shown in Figs. 6-6a, insert 32 includes apertures 34 that are constructed to receive groups of bristles to be formed into tufts. The bristles are transferred to the insert by the bristle transfer portion 100 of bristle tufting machine 24, shown in Figs. 4-4c.

As shown in Figs. 3,3a and 3f, prior to each transfer of bristles by the bristle transfer portion, the bristles in the bristle magazine are"tamped down",

to align them properly and eliminate any stray bristles, by a tamper 36. Tamper 36 is mounted on a tamper slide 38 constructed to move the tamper vertically between a position in which it is spaced from the bristle magazine 28 and a position in which it contacts the bristle magazine 28.

Once the bristles have been tamped down, a plurality of hollow tubes 102, mounted on a vertically slidable tube plate 103, are inserted upwardly into the bristle magazine 28 so that bristles are received into the tubes (see Fig. 4a). During this procedure, tamper 36 tamps down the bristles, preventing them from being forced out of the magazine by the tubes and causing them to enter the tubes.

The tubes containing the bristles are then retracted to their initial position (Fig. 4), and moved horizontally to a position beneath the insert 32, in which tubes 102 are aligned with apertures 34 in insert 32. Tubes 102 are then inserted through apertures 30 in the floor plate into apertures 34 of the insert 32.

In this position, a plurality of pins 104, mounted on a vertically slidable pin plate 105 so that each pin 104 is partially inserted into a corresponding tube 102, are moved upwardly so that they extend further into tubes 102. Insertion of pins 104 into tubes 102 forces the bristles upwardly out of the tubes and into the apertures 34 of insert 32 (see, e. g., Fig. 8). The pins may be pushed up to the same extent, if a flat brushing surface is desired, or to different extents, as shown in Fig. 8, if a contoured brushing surface is desired. Thus, a contoured surface can be easily achieved without the need for a separate trimming step after the brush is finished. Preferably, as shown in Fig. 8, insert grippers 126 (an element of the pick-and-place device used to move the insert, described below) are lowered during insertion of the pins further into the tubes, and include a contour plate 127 having the same topography as that of the end-rounded ends of the bristle tufts, i. e., the reverse topography of the second ends of the bristles that extend upwardly from the insert. This causes the bristles to be forced into the desired contour against the profile defined by the raised position of the pins in the tubes.

Preferably, as shown, the bristle transfer portion 100 of the tufting machine includes two sets of tubes 102 and pins 104, spaced from each other a distance equal to the distance between each of the insert positions (left and right) and the central bristle magazine 28. The two sets of tubes and pins are carried by a

bottom plate 106 that is mounted on a side movement cylinder 108 for horizontal reciprocation between two positions: a first position (Figs. 4 and 4a) in which the two sets of tubes and pins are aligned under the left-hand insert position and the bristle magazine 28, and a second position (Figs. 4b and 4c) in which the two sets of tubes and pins are aligned under the bristle magazine 28 and the right-hand insert position. By reciprocating the bottom plate 106 from one position to the other after each vertical movement of the tubes, a single vertical movement can both fill one set of tubes with bristles and simultaneously fill the insert under which the other set of tubes (full of bristles) is positioned.

As soon as the ends of the bristle groups have been pushed through insert 32 by pins 104, insert grippers 126 are moved out of the way and the bristle ends extending above the insert surface are fused to form fused portions 109, e. g., as shown in Fig. 7. The shape of the fused portions can be varied to obtain a desired shape by varying the conditions under which the ends are fused, as would be understood by one skilled in the art. Spherical fused portions may tend to rotate ball-in-socket fashion in the molded brush head, and thus other shapes, e. g., flattened spheres or"peanut shaped", are generally preferred.

Fusing is performed using the upper, fusing portion 110 of the bristle tufting machine, shown in Figs. 3-3f, as will be described below. In order to obtain fused portions having adequate diameter to prevent the fused portions from being forced through apertures 34 during molding, it is important that a sufficient length of the second ends of the bristles extend above the surface of the insert during fusing. Preferably, at least 0.10" of bristle extends above the insert, more preferably 0.15" to 0.25".

It is also preferred that the fused portions extend a distance into the molding cavity during molding, rather than sitting flush with the surface of the insert. Thus, molding material can flow around the bristle tufts below the fused portion, preventing the tufts from pivoting ball-in-socket fashion in the finished brush. (See Fig. 7b). To enable the fused portions to extend into the cavity in this manner, the insert is preferably provided with a tuft support 111, as shown in Fig. 7, to support the fused portions 109 above the insert surface. Preferably, the fused portions 109 extend from about 0.001" to 0.060" above the surface of the

insert, more preferably from about 0.005" to 0.015". If the fused portions are too close to the insert, the individual tufts will tend to pivot in their"sockets"after molding; if the fused portions extend too far above the insert surface it will become difficult to remove the molded brush from the molding cavity.

Fusing portion 110 includes a pair of identical fusing devices 112, positioned over the left and right-hand insert positions of the floor plate. Each of the fusing devices 112 includes a heating device 114, positioned above and in alignment with one of the insert positions, and a heater slide 116 (preferably a guided air cylinder) constructed to move the heater element vertically from a retracted position above the insert (Fig. 3), to a heating position in which it engages the bristle ends extending through an insert disposed in the corresponding insert position (e. g., Fig. 3a). Each fusing device 112 preferably also includes an insulating material 118 surrounding the heating device, and a door 120 enclosing the heating device, when the heating device is in its retracted position.

When an insert is filled, and the ends of the bristle groups are pushed through the insert by the pins, the heating device that is positioned above the filled insert is lowered into the heating position (Fig. 3a). The ends of the bristles extending through the insert are then fused by the heating device, forming the fused portions 109 shown in Fig. 7. Once the ends are fused, pins 104 and tubes 102 are retracted from the insert. The insert is then ready to be positioned in a mold tool 107 (Fig. 7a) which is then mounted in molding machine 18 and which defines a portion of the molding cavity of the molding machine, after which molding material, e. g., any suitable thermoplastic material, is injected into the molding cavity to form a completed toothbrush.

The sequence of positions shown in Figs. 3-3f illustrates the sequence of movement of inserts into and out of the bristle tufting machine. This sequence corresponds to the sequence of horizontal and vertical reciprocation of the tubes and pins that was described above. Thus, in Figs. 3 and 3a, a first insert is in the left-hand insert position in its empty and filled states, respectively. Fig. 3b shows the pick-and-place device 124 that is used to transfer this first insert to the next station in the bristle forming process (the pick-and-place device was omitted from Figs. 3,3a, 3e and 3f for clarity), while simultaneously bringing a second, empty

insert in to the right-hand position of the bristle tufting machine. In Fig. 3c, the insert grippers 126 of pick and place device 124 are lowered and engaged upon first insert 32a, and are translated, by the drive linkage 128, from the position shown in Fig. 3c to the position shown in Fig. 3d, in which the first insert 32a has been moved to the next station in the brush forming process (not shown), and a second insert 32b is over the right-hand insert position. The pick-and-place device then deposits the insert in the right-hand insert position. At the same time, the tubes 102 and pins 104 have shifted right to their right-hand positions (Fig. 4b); in this new position the empty left-hand set of tubes (emptied into insert 32a while it was in the left-hand station) will be filled from the central magazine and the filled right-hand set of tubes (filled from the central magazine while the pins/tubes were in the left-hand position) will be inserted into insert 32b.

Figs. 5 and 5a show the lowermost, tube/pin driving portion 130 of the bristle tufting machine (floor plate 26 is included, for reference, but the bristle transfer portion of the machine is omitted, for clarity). The tube/pin driving portion 130 includes four ballscrew drive servomotors 132, two of which drive the two sets of pins up and down, and the other two of which drive the two sets of tubes up and down, allowing the individual sets of tubes and pins to move independently.

Ballscrew drive servomotors 132 are connected to ball screws 134, and ballscrew connection shaft 136, to transmit the driving force to the pins and tubes.

Other embodiments are within the claims. For example, while the invention has been discussed above in relation to oral brushes, the invention may be used to form any type of brush having fusable bristles, e. g., hairbrushes, cleaning brushes and brooms. Moreover, although the tufting machine illustrated above is constructed to form a plurality of tufts, the insert could include a single aperture, and the bristle transfer assembly a single pin and tube, to form a single tuft, e. g., if a toothbrush with one large tuft were desired. The single tuft may be in the form of, e. g., a slot, ellipse, multiconic shape, or any other desired geometry. Further, multiple tubes and pins could be used to form such a single-tuft brush. The tufts need not be molded into the brush head at a 90 degree angle as shown, any desired angle could be used.