Abstract:
Methods and devices are provided for forming filament bundles of long, continuous strands of filaments. The methods include bonding the long, continuous stands of filaments together so that they cannot move axially with respect to any other filament in the bundle. Methods of bonding include ultrasonic welding, freezing or applying adhesive.

Description:
TECHNICAL FIELD 
   This invention relates to brush manufacturing, and more particularly to filament preparation. 
   BACKGROUND 
   Conventional toothbrushes generally include tufts of bristles mounted on the head of an oral brush handle. One method of manufacturing toothbrushes involves placing tufts of finished (end-rounded) bristles so that their unfinished ends extend into a mold cavity, and forming the toothbrush body around the unfinished ends of the tufts by injection molding, thereby anchoring the tufts in the toothbrush body. The tufts are held in the mold cavity by a mold bar having blind holes that correspond to the desired positioning of the tufts on the finished brush. The finished bristles may be formed by a process that includes unwinding a rope of filaments from a spool, end-rounding the free end of the filaments, cutting off a portion of the rope that is adjacent the free end of the filaments to form bristles having the desired length, and placing the bristles into a rectangular box, called a magazine. Tufts are then formed by picking groups of bristles from the magazine. 
   However, problems often occur when bristles are picked from the magazine and transferred to the machine that fills the moldbar. A picker device attempts to repeatedly choose the proper number of bristles to form a tuft. However, the inherent difficulty in this task may result in tufts of bristles that are either too small or too large for the blind holes in the moldbar. If a tuft is too small, the blind hole is not sufficiently filled and plastic will flow into the hole when the handle is formed. If a tuft is too large, one or several bristles may not enter the moldbar, but rather curl to the side and prevent the complete insertion of the tuft into the moldbar, which may then interfere with molding. 
   These problems can be addressed by filling the moldbar with continuous filament bunches supplied directly from spools. Methods and machines used to fill moldbars from a continuous filament stream is described in U.S. patent application Ser. No. 09/863,193, entitled TUFTING ORAL BRUSHES, the disclosure of which is incorporated herein by reference. Toothbrushes using these methods can be manufactured relatively easily and economically by an injection molding process that includes advancing free ends of strands of continuous filaments into a moldbar. The filaments are not cut to bristle-length until after the free ends of the filaments have been advanced into the holes in the moldbar, thus reducing or eliminating the problems that tend to occur when handling cut tufts, as discussed above. 
   Problems may arise, however, when supplying the spool fed tufting machine due to catenary problems inherent in the spools of continuous filaments. Problems include non-uniform tension and length between individual filaments, which are generally the result of the filament manufacturing process. These tension and length differentials may cause individual filaments to eventually loop as the filament bundle is pulled from the spool, as shown in  FIGS. 1A–1D , or wrap around the bundle, as shown in  FIG. 2 . 
   When these problems occur, the dimensions of the filament bundle entering the feeding device of the spool fed tufting machine may vary. For example, when filaments twist around each other, the diameter of the entire bundle increases. Since the tolerances on the feeding device are generally tight, the area of the bundle with the increased diameter may not fit into the feeding device. The area of increased diameter also may not fit into the blind holes of the moldbar. 
   Further, when individual filaments have little tension, those filaments tend to slide axially relative to the other filaments, back in the direction of the spool during feeding. As the individual filament continues to be moved back towards the spool, and the slack increases, a loop may eventually form. This loop may eventually snag or break the filament. 
   SUMMARY 
   The inventors have found that these catenary problems can be reduced or even eliminated by inhibiting or preventing movement of the filaments relative to each other. 
   One method of preventing the filaments from moving relative to each other is to weld the filaments to each other at spaced intervals. This welding process can be done, for example, just prior to the bundle entering the feeding device, or in a pre-manufacturing step in which the bundle is welded and re-wound onto spools that are then supplied to the tufting machine. Welding the filaments in the bundle to one another prevents the filaments from moving relative to each other, either axially or radially around each other. By preventing axial movement, the individual filaments cannot move back towards the spool, thereby preventing loops from forming. By preventing movement radially around each other, the individual filaments cannot wrap around the bundle, thereby preventing diameter changes. Further, since the filament bundle can be cut so as to have the weld placed in the mold cavity when the toothbrush handle is formed, the weld can be shaped, or a hole can be formed in the weld, to form an anchor. By using the weld to form an anchor, one can eliminate the separate step of forming anchors by heating the filament bundles in the moldbar and “mushrooming” the ends, as is well known in the art. 
   Another method of preventing the filaments from moving relative to each other is to temporarily bond the filaments to each other using a soluble adhesive. The adhesive could be applied either in a pre-manufacturing step or just prior to the filament bundle entering the feeding device. Once the brush handle has been formed, the soluble adhesive is removed from the exposed bristles. 
   A further method of preventing the filaments from moving relative to each other is to temporarily bond the filaments to each other using ice. A liquid is applied to the filament bundle and the bundle is passed through a stream of chilling liquid or gas, such as liquid nitrogen. The liquid nitrogen will instantly freeze the bundle into a solid rod, which will then easily slide through the feeding device. The ice can then be melted, such as by heating in the tufting machine or the by the frictional heating of the filaments during the end rounding process. 
   In one aspect, the invention features a method for manufacturing filament bundles including: (a) feeding a bundle comprising a plurality of long, continuous strands of filaments through a bonding device; and (b) forming at least one bond between the plurality of continuous strands of filaments, wherein forming the at least one bond between the plurality of continuous strands of filaments prevents the filaments from moving axially with respect to any other one of the plurality of continuous strands of filaments. 
   Some implementations include one or more of the following features. The method further includes forming a plurality of bonds axially spaced along the filament bundle. The plurality of bonds are equally spaced axially along the filament bundle. The bonds are formed by welding. The welding may be accomplished by ultrasonic welding. The ultrasonic welding is done by using a horn and anvil. The anvil includes a metal base, a channel running through the metal base through which the filament bundle passes, and non-metallic walls lining the sides of the channel to prevent the horn from welding to the anvil. The horn and anvil together will form the shape of a final brush tuft. The width of the channel is adjustable. The horn is a bar horn. The ultrasonic welding is accomplished by an ultrasonic sewing device. 
   In another aspect, the invention includes shaping the bond to a finished tuft shape. The bond may be shaped to include an undercut. The bond may be shaped to include a hole through the bond. The method further includes tensioning the filament bundle before forming the bond. 
   In a further aspect, the invention includes forming an axially continuous bond. In one aspect, the axially continuous bond is formed by freezing the filament bundle. The filament bundle is frozen by (a) applying a liquid to the filament bundle to wet the filaments; and (b) applying a material that causes rapid freezing to the wet filaments to freeze the liquid. The material that causes rapid freezing is liquid nitrogen. In another aspect, the axially continuous bond is formed by apply adhesive to the filament bundle. The adhesive is water soluble. The method of applying adhesive to the filament bundle further includes removing the adhesive after the filament bundle has been fed through a tufting machine. 
   In another aspect, the invention includes forming a toothbrush by (a) feeding a bundle comprising a plurality of long, continuous strands of filaments through a bonding device; (b) forming bonds between the plurality of continuous strands of filaments, wherein the bonds are equally spaced axially along the bundle; (c) feeding the bundle into a tufting machine; wherein the tufting machine advances the plurality of continuous strands of filaments into a moldbar; (d) cutting the bundle adjacent the bonds so that the bonds extends above a surface of the moldbar; (e) placing the moldbar in a molding machine so that the bonds extend into a mold cavity defined in part by the moldbar, the mold cavity being shaped to form the body of the toothbrush; and (f) delivering resin into the mold cavity to form a toothbrush body around the bonds. The method further includes forming an opening in each bond so that the resin delivered into the mold cavity flows through the opening. The method also includes forming an undercut in each bond so that the resin delivered in to the mold cavity flows into the undercut. The bundle is cut adjacent the bonds so that the bonds extend into a blind hole in the moldbar, below the surface of the moldbar. The bonds are equally spaced axially along the bundle at a distance less than the distance equal to a tuft length on a finished brush. 
   In a further aspect, the invention includes winding the bundle onto a spool after forming the bonds and supplying the bonded bundle to the tufting machine from the spool. The step of forming the bonds is done by ultrasonic welding. 
   In a further aspect, the invention features a continuous filament bundle for use in a spool-fed tufting machine comprising: (a) a plurality of long, continuous strands of filaments; and (b) at least one bond between the plurality of continuous strands of filaments, wherein the at least one bond between the plurality of continuous strands of filaments prevents the filaments from moving axially with respect to any other one of the plurality of continuous strands of filaments. The filament bundle includes a plurality of bonds spaced axially along the filament bundle. The bonds are equally spaced axially along the filament bundle. The bond is a weld. The weld is an ultrasonic weld. The bond is shaped like the finished tuft. The bond includes an undercut. The bond includes a hole through the bond. The bond is an axially continuous bond. The axially continuous bond is formed by freezing the filament bundle. 
   Another aspect of the invention includes an ultrasonic welding device including (a) an anvil comprising a metal base with a top surface and a channel in the metal base along the top surface that defines at least a portion of a shape of a tuft through which a filament bundle passes, the channel having two side walls and a bottom; and (b) a horn that moves relative to the anvil, wherein the horn can be moved into and out of contact with the filament bundle in the channel. The ultrasonic device includes one or more of the following feature. The horn forms at least a portion of the shape of the final tuft. The channel further includes non-metallic walls lining the side walls of the channel. The non-metallic walls have a higher melting point than the filament bundles. The non-metallic walls can be either polyether-imide, polyether-ether-ketones, polysulfones, fluoropolymer, polytetrafluorethylene (Teflon®), phenolic resin, rubber, epoxy, ceramic materials and hardwood. The anvil further includes spring loaded slides adjacent the channel that constrain the filament bundle and move with the horn as the horn makes contact with the spring loaded slides and moves into contact with the filament bundle in the channel. The spring-loaded slides are non-metallic. The side walls of the channel are adjustable relative to each other to adjust the width of the channel. 
   Other aspects include the device having a bar horn. The horn forms an opening through the bond. The horn forms an undercut in the bond. The anvil forms an opening in through the bond. The anvil forms an undercut in the bond. 
   The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features and advantages of the invention will be apparent from the description and drawings, and from the claims. 

   
     DESCRIPTION OF DRAWINGS 
       FIGS. 1A–1D  are sequential side views of a filament bundle with one filament looping upon itself. 
       FIG. 2  is a side view of a filament bundle with one filament twisting around the bundle. 
       FIG. 3  is a schematic view of a welding process according to one embodiment of the invention. 
       FIG. 4  is a side schematic view of a filament bundle welded in accordance with an embodiment of the invention. 
       FIG. 4A  is a cross-sectional view of the filament bundles in a mold bar in accordance with an embodiment of the invention. 
       FIG. 5  is a top view of an ultrasonic welding anvil according to one embodiment of the invention. 
       FIG. 6  is a cross-sectional view of the ultrasonic welding anvil of  FIG. 5  taken along line  6 — 6  and its associated ultrasonic welding horn. 
       FIG. 7  is a front view of an ultrasonic welding anvil and horn according to another embodiment of the invention. 
       FIG. 8  is a side view of the ultrasonic welding horn of  FIG. 7 . 
       FIG. 9  is a side view of a finished tuft according to an embodiment of the invention. 
       FIG. 10  is a side view of a finished tuft according to another embodiment of the invention. 
       FIG. 11  is cross-sectional view of a toothbrush handle according to one embodiment of the invention. 
       FIG. 12  is a side view of an ultrasonic welding bar horn according to one embodiment of the invention. 
       FIG. 13  is a side view of an ultrasonic sewing device according to one embodiment of the invention. 
       FIG. 14  is a schematic view of a filament bundle bonded according to another embodiment of the invention. 
       FIG. 15  is a schematic view of a filament bundle bonded according to another embodiment of the invention. 
   

   Like reference symbols in the various drawings indicate like elements. 
   DETAILED DESCRIPTION 
   A process for ultrasonic welding of a filament bundle generally includes the following steps, which will be discussed briefly now, and explained in further detail below. Generally referring to  FIG. 3 , a welding setup  10  is supplied by a pay-off spool  12  containing a filament bundle  14 , the bundle corresponding in number of filaments to a tuft on a finished toothbrush. The filament bundle  14  is fed through a tensioning device  16 , which is generally known in the art and in the textile art. Next, the filament bundle  14  goes through a decoupling device  18 , which consists of nip rollers  20  and  22 . The decoupling device  18 , in conjunction with a second decoupling device  24 , holds the filament bundle  14  in place while in the welding area  26 . The filament bundle  14  is pulled through a shaping block  28 , which forms the filament bundle into the shape of a tuft on a finished toothbrush. A second shaping block  30  helps hold the filament bundle in the desired shape as the filament bundle passes through the anvil  32  of the welding device  36 . 
   The welding device  36  is preferably an ultrasonic welding set up with a custom anvil  32  and horn  34 . The shape of the anvil and horn, which will be described more fully below, corresponds to the shape of the tuft on a finished toothbrush. While the decoupling devices  18  and  24  hold the filament bundle  14  and prevent it from moving, the horn  34  of the welding device  36  engages the filament bundle in the anvil  32  and ultrasonically welds the individual filaments  52  in the filament bundle  14  together. The resultant weld  50  (shown in  FIG. 4 ) will have the cross-sectional shape of the final tuft on the finished toothbrush. 
   The filament bundle  14  exits the weld area  26  through the second decoupling device  24 , The filament bundle is then fed through an advancing mechanism  38 , which indexes the filament bundle forward and locks during the actual welding step. The advancing mechanism only rotates in one direction, so as to allow the filament bundle to advance forward, and prevent the filament bundle from slipping backwards towards the welding area  26 . The filament bundle is generally advanced in an indexing fashion a distance T (see  FIG. 4 ), which will vary depending on the final tuft length for the brush being manufactured from the filament bundle, and other welds (e.g., welds  54  and  56 ) are formed after each indexing movement. Finally, the finished filament bundle  14  is wound onto spool  40 , which is then supplied to a tufting machine. 
   Referring to  FIGS. 4 and 4A , the welds  50 ,  54 ,  56  are generally spaced such that a length F is left unbound between welds. Length F is equal to the length of the working, free-end of the tuft that will be pushed into the blind holes  57  of the moldbar  58 , as described in application Ser. No. 09/863,193. The weld length W is generally equal to the amount of tuft that will extend into the mold cavity and will therefore be embedded into the finished toothbrush handle. The total length T of the tuft is equal to the weld length plus the free-end of the tuft. These lengths can be adjusted for each filament bundle depending on the finished tuft that the filament bundle will be used to manufacture. 
   The Tensioning Device 
   The tensioning device  16  is used in conjunction with the pay-off spool  12  to pull on the filament bundle. The pay-off spool can move in either direction to help the tensioning device keep a constant tension on the filament bundle  14 . Tension will tend to stretch the shorter filaments to a length closer to the longer filaments, helping to lessen the amount of slack that builds as the filament bundle is released from the pay-off spool and, thereby, lessening the possibility of the longer filaments looping. The tension will also help keep the shape of the filament bundle in the welding area  26  by not allowing any filaments to bow out of the filament bundle as shown in  FIG. 1A  or  1 B. The necessary tension will vary depending on the number and diameter of filaments in the filament bundle. For example, a nail tuft with 37 filaments, each filament having a 0.008 inch diameter, requires approximately 4 lbs. of tension. A tuft of 139 filaments with the same type of filaments requires approximately 10 lbs. of tension. 
   The Horn and Anvil 
   Referring to  FIGS. 5 and 6 , the anvil  32  includes a channel  63  through which the filament bundle  14  passes. Ultrasonic welding causes heating and plastic flow in the thermoplastic filaments by passing high frequency waves from a metallic horn  34 , through the thermoplastic filaments and into the metallic anvil  32 . While flow is desirable within the filament bundle and between individual filaments to bond them together, tight tolerances between the horn and anvil are necessary to prevent undesirable flow into the clearance between the horn and anvil, which would cause flash on the fused area. Flash would include overflow outside of the desired shape of the weld that would not allow the weld to pass through the feeding device of the tufting machine. To avoid such flash, the clearance between the horn and anvil must be extremely small, preferably less than 0.0005 inches. However, if the metal horn touches the metal anvil, the ultrasonic waves will cause the horn to weld to the anvil. Because of the difficulty in aligning the horn and anvil when only 0.0005 inches of clearance are desirable, the anvil can be fitted with non-metallic walls  64  and  66  ( 96  and  98  in  FIG. 7 ). The non-metallic walls are preferably a plastic material, such as Teflon, with a higher melting point than the filaments, which are usually nylon or polybutylene terephthalate (PBT). Other possible materials for the non-metallic walls include engineering polymers such as polyether-imide and polyether-ether-ketones (PEEK), thermoset materials such as rubber and epoxy, ceramics and hardwoods. Any desired material may be used for the walls  64  and  66  as long as the melting point of the non-metallic wall is higher than that of the filaments being ultrasonically welded. These non-metallic walls allow for small or no clearance while helping to prevent the accidental welding of the horn to the anvil. 
   Again referring to  FIGS. 5 and 6 , the anvil also includes spring loaded slides  70  and  72 , which help to constrain the filaments in the filament bundle  14  until the horn  34  sufficiently compresses the filament bundle  14 . These spring loaded slides  70  and  72  are made of a non-metallic material to prevent welding the horn to the anvil. As the horn  34  moves down towards the anvil  32 , it contacts the spring loaded slides  70  and  72 , causing them to also move down, into cavities  74  and  76 , thereby compressing springs  78  and  80 . The horn stops when the filament bundle is sufficiently compressed between the horn  34  and the anvil base  82 . Ultrasonic waves are then emitted. The ultrasonic waves pass from the horn  34 , through the filament bundle  14  and into the metallic base  82  of the anvil  32 . 
   The horn  34  includes a shaped area  86  that, when combined with the shape of the anvil  82 , forms the weld into the cross-sectional shape of the tuft in the finished toothbrush, in this case round. All edges that run parallel to the filament bundle, such as  84  (and edges  92  and  93  in  FIG. 7 ), are sharp rather than rounded to avoid forming flash caused by the thermoplastic filaments flowing into the space a rounded edge would create. However, edges that run perpendicular to the direction of the filament bundle, such as  85  (and  110  and  112  in  FIG. 8 ), are rounded. Rounding the edges  85 ,  110  and  112  allows for gradual compression of the filament bundle prior to welding and will also help avoid local energy concentrations across the filament bundle which can cut individual filaments. 
     FIG. 7  shows another embodiment of a horn  90  and anvil  92 . This particular embodiment is shaped to make flat nail tufts. The anvil  92  includes a channel  94  through which the filament bundle  14  passes. The channel is lined by Teflon walls  96  and  98 . In this embodiment, the width of the channel  94  is adjustable so it can be used with various horns. Teflon walls  96  and  98  are held in place by wall clamps  100  and  102 , which are fixed to anvil base  104  by bolts  106  and  108 . The bolts  106  and  108  are engaged with nuts that ride in T-slots (not shown) machined into the anvil base  104 . To adjust the width of the channel, the bolts  106  and  108  are loosened and wall clamps  100  and  102  can move in either direction indicted by arrow B. Once the correct adjustment has been made, the bolts  106  and  108  are tightened. This adjustment can also be accomplished by advancing the horn  90  into the channel  94 , sliding the Teflon walls into contact with the horn, then tightening the bolts while maintaining contact between the walls and the horn. 
     FIG. 8  shows the horn  90  from a side view. As can be seen, edges  110  and  112  have been rounded to allow for the gradual compression of the filament bundle prior to welding and to also help avoid local energy concentrations which can cut individual filaments, as described above. 
   Shaping the Weld 
   Referring to  FIGS. 9 and 10 , the weld can be shaped to help anchor the tuft in the finished toothbrush. Conventionally, prior to molding a toothbrush handle around the tufts extending from the moldbar, the tufts may be melted to fuse the ends together and to give the ends a bulb or mushroom shape. This shape anchors the tuft in the handle by preventing the tuft from sliding out of the handle. A weld made using the present invention can be used to anchor the tufts, eliminating the need for this additional fusing step.  FIG. 9  shows a tuft  120  with a weld  122  made by the present invention. The weld  122  includes a hole  124  through the tuft  120 . When tuft  120  is in the moldbar, the weld  122  will be in the mold cavity, and as the toothbrush handle is formed, the handle material will flow through the hole  124 , thereby anchoring the tuft in place. The hole may be made by adding a point on the horn that will concentrate the ultrasonic waves, thereby creating a hole in the weld. Alternatively, the hole could be formed in a finished weld by another ultrasonic horn or a mechanical punch. Further, the hole can be round, square or any other shape so long as the handle material can flow through to anchor the tuft. 
     FIG. 10  shows another embodiment of a tuft  130  with a weld  132  made by the present invention. The weld  132  includes an undercut  134  around the entire tuft  130 . When tuft  130  is in the moldbar, the weld  132  will be in the mold cavity, and as the toothbrush handle is formed, the handle material will flow around undercut  134 , thereby anchoring the tuft in place. This undercut maybe formed by shaping the horn and anvil to compress the filament bundle more in the middle of the weld, thereby giving the final weld a smaller diameter in the middle of the weld. 
   A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, the shaping blocks  28  and  30  ( FIG. 3 ) are not necessary. The anvil can be designed such that the anvil itself fully shapes the filament bundle. Further, the positions of tensioning device  16  and advancing mechanism  38  can be switched, or both can be on the same side of the welding area  26 , either before or after the welding area  26 . 
   Moreover, although, as described above, the spacing of the weld is generally every tuft length T (see  FIG. 4 ), the spacing of the welds may be at an interval equal to X number of tuft lengths. For example, it is possible to weld only every 5 tuft lengths, or 5T. In this example, the welding setup  10  would index the filament bundle a distance equal to 5T for each weld. 
   It is also possible to vary the weld length W (see  FIG. 4 ). Referring to  FIG. 11 , tuft  140  has a weld  142  that is entirely encapsulated within a toothbrush handle  144 . Weld  142  is generally the desirable length for most applications. However, in some cases a longer or shorter weld is desirable. For example, filaments of a diameter smaller than the 0.008 inches described above are sometimes desirable because these thinner filaments can more easily reach in between teeth. However, filaments with diameters less than 0.008 inches tend to more easily bend and quickly wear at the lengths necessary to reach from the toothbrush handle to in between the teeth. This problem can be solved by increasing the weld length to reach beyond the toothbrush handle  144 , such as shown by tuft  150  in  FIG. 11 . Tuft  150  includes a weld  152  that extends from within the toothbrush handle  144  to almost half the length of the free end of the tuft  150 . While it is necessary to keep the tuft long to reach in between the teeth, only a portion of the total tuft length actually penetrates into the interdental spaces. Therefore, the rest of the tuft  150  can be welded together to give the smaller filaments structural strength. Alternatively, the distance between welds F ( FIG. 4 ) can be decreased so as to have more than one weld in a tuft length. A fuse in the middle of the tuft  154  would stiffen the tuft  156  while giving a different bending characteristic than the longer weld described above. Further, the fuse in the middle of the tuft  154  can be a different length than the fuse within the handle  155 . 
   Referring to  FIG. 12 , the welds can also be formed using a bar horn  160 . The bar horn  160  has multiple horn tips  162 ,  163 ,  164 , and  165 , which are spaced apart a distance F (see also  FIG. 4 ). The filament bundle would therefore be welded at multiple points at one time. In the example shown, four welds will be made each cycle. This allows the system to index the filament bundle four times farther after each weld cycle, and will therefore cut the time to process a complete spool to 25% of the time it would take using a single horn if all other process parameters remain the same. 
   Referring to  FIG. 13 , ultrasonic sewing may also be used to produce multiple welds on a continuous basis. The filament bundle  14  is pulled at a constant rate through a space between a stationary horn  170  and a rotating anvil  172 . The rotating anvil has several high spots  174 ,  175 ,  176 , and  177 , that contact the filament bundle at spaced intervals. The distance between any two high spots would be equal to the free tuft length F. Ultrasonic sewing will allow the process to be continuous and faster than the intermittent indexing, which requires overcoming inertia to move the filament bundle. 
   Further, the filament bundle  14  can be made up of filaments from multiple spools. The multiple spools may contain filament bundles with fewer filaments, or can even be spools of individual filaments. The filaments combined in the bundle can either be all the same type of filament or different filaments. For example, indicator filaments from one spool can be mixed with non-indicator filaments from another spool. Also, filaments of various colors, materials and diameters can be combined from multiple spools. 
   Other methods of bonding the filament bundle together may also be employed. For example, referring to  FIG. 14 , the filament bundle is impregnated with a soluble adhesive  184  that bonds the individual filaments together. The filament bundle  178  is supplied from a pay-off spool  180  and fed through tensioning device  182 . The filament bundle  178  is then passed through a pool or spray of adhesive  184 , which is allowed to dry before the bundle is re-wound onto a spool  40 . In addition, shaping blocks similar to those in  FIG. 3  ( 28  and  30 ) may be used one either side of the pool or spray of adhesive  184  to shape the filament cross-section. The filament bundle is then used to make a toothbrush in the tufting machine. After the handle has been formed, the adhesive is dissolved using the appropriate solvent. Preferably, the adhesive is a water soluble adhesive. Alternatively, the adhesive may be applied to the filament bundle just prior to the bundle entering the feeding device. The adhesive may also be dissolved after the filaments are placed in the moldbar, but prior to forming the toothbrush handle. 
   Another method of bonding the filaments is to freeze the filament bundle. Referring to  FIG. 15 , the filament bundle  190  is supplied from a pay-off spool  192  and fed through tensioning device  194 . Water is applied to the filament bundle, either by spraying the water  196  on the bundle, as shown, or by passing the bundle through a pool of water (not shown). In addition, shaping blocks similar to those in  FIG. 3  ( 28  and  30 ) may be used one either side of the pool or spray of adhesive  184  to shape the filament cross-section. The bundle is then rapidly frozen, which can be accomplished by blasting the bundle with a shot of liquid nitrogen  198 , or any other gas or liquid that would cause rapid freezing. Alternatively, the bundle can be pulled through a cooling chamber (not shown) which freezes the water. The frozen rod is then threaded into the feeding device  200 . Once the frozen rod is past the feeding device, the ice can be melted. Melting can be accomplished in any desired manner, such as by heating the manifold of the tufting machine, that will not damage the filaments. Melting may also be accomplished through the frictional forces encountered during end rounding. 
   While the invention has been described by using a toothbrush as an example, it should be understood that any type of brush or article with bristle tufts can be made using the described methods and devices. 
   Accordingly, other embodiments are within the scope of the following claims.