Patent Publication Number: US-6666524-B2

Title: End-rounding devices and methods for end-rounding

Description:
TECHNICAL FIELD 
     This invention relates to methods and devices for end-rounding bristles and filaments that are used to make bristles. 
     BACKGROUND 
     Conventional toothbrushes generally include tufts of bristles mounted on the head of an oral brush handle. The working ends (i.e.—the end that contacts the teeth and gums) of the bristles generally must be smoothed to remove sharp edges that might cut or irritate the gums. This process is known as end-rounding. 
     In most end-rounding methods, the working ends of the bristles are contacted with a sanding disc. Generally, these sanding discs are rotated using an electric motor. The size and weight of an electric motor generally makes it impractical to move the end-rounder. 
     SUMMARY 
     The present invention features methods and devices for end-rounding bristles or continuous filaments that are used to make bristles. 
     In some implementations, the end-rounding device is movable into and out of contact with the filament ends, so that the filaments can be continuously fed in a single axial direction, without the bending and stress associated with moving the filaments into and out of contact with the end-rounder. Specifically, the end-rounder is moved into and out of position below the axial path of the ropes that eventually are cut into bristles. 
     The end-rounding device is air driven, light and has a low profile. The end-rounding device also has an ever-changing elliptical path, which attacks the bristles from all sides, producing a well-rounded bristle. 
     In one aspect, the invention features a device for end-rounding bristles including a sanding wheel mounted to a pneumatically driven support. 
     Some implementations include one or more of the following features. The pneumatically driven support includes a turbine. The pneumatically driven support includes a planetary drive mechanism that is driven by rotation of the turbine. The planetary drive mechanism includes a planet gear rotatably mounted on the pneumatically driven support and a fixed ring gear in engagement with the planet gear. 
     In another aspect, the invention features an end-rounding device that is less than about 2 inches in height. Preferably, the device weighs less than 5 pounds. 
     In another aspect, the invention features an end-rounding device having a planetary drive mechanism that is constructed to move the sanding wheel in an elliptical path. 
     Some implementations include one or more of the following features. The elliptical path is varied. The tooth ratio of the ring gear to the planet gear is about 2:1. The tooth ratio of the ring gear to the planet gear is slightly greater than 2:1. The pneumatically driven support is constructed to rotate at up to 5,000 revolutions per minute. The pneumatically driven support is constructed to rotate at up to 10,000 revolutions per minute. The sanding wheel is mounted on the pneumatically driven support so the center of the sanding wheel is within the pitch circle defined by the planet gear. 
     In another aspect, the invention features a sanding wheel and a planetary drive mechanism constructed to move the sanding wheel in an elliptical path. The planetary drive mechanism includes a planet carrier, a planet gear mounted on the planet carrier and a stationary ring gear wherein the planet gear engages the stationary ring gear and the planet carrier drives the planet gear. The tooth ratio of the stationary ring gear to the planet gear is slightly less than 2:1. The sanding wheel is mounted to the planet gear. The sanding wheel is mounted within a pitch circle defined by the planet gear. The planet carrier is pneumatically driven. The planet carrier is a turbine. The device is constructed to vary the direction of the elliptical path during rotation of the sanding wheel. 
     In a further aspect, the invention includes a feeding device constructed to advance a plurality of filaments through the machine in an axial direction and an end-rounding device constructed to be moved transversely relative to the axial direction, back and forth between a first position in which the end-rounding device is in contact with free ends of the filaments, and a second position in which the end-rounding device is not in contact with the free ends of the filaments. 
     In still another aspect, the invention features a method for end-rounding bristles including contacting the ends of bristles with an end-rounding device having a sanding wheel, the end-rounding device being constructed to move the sanding wheel in an elliptical path. Preferably, the end-rounding device includes a planetary drive mechanism and the planetary drive mechanism is pneumatically driven. 
     In another aspect, the invention features a method for end-rounding bristles including contacting ends of bristles with an end-rounding device including a sanding wheel and a pneumatically driven support for the sanding wheel. 
     Other features and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     DESCRIPTION OF DRAWINGS 
     FIG. 1 is a perspective view of a toothbrush having bristle tufts that extend in different directions and at different angles. 
     FIG. 2 is a flow diagram of general steps followed by a tufting machine according to one embodiment of the invention. 
     FIGS. 3A and 3B are flow diagrams of specific steps followed by the tufting machine. 
     FIG. 4 is a partial cut-away front view of a tufting machine according to one embodiment of the invention. 
     FIG. 5 is a side view of the tufting machine shown in FIG.  4 . 
     FIG. 6A is a top view of a feeding device of the tufting machine shown in FIG. 4 taken along line  6 A— 6 A, with the feeding device shown in its unbiased state. 
     FIG. 6B is a cross-sectional view of the feeding device shown in FIG. 6A, taken along line  6 B— 6 B. 
     FIG. 6C is an enlarged view of a portion of the feeding device shown in FIG.  6 B. 
     FIGS. 7A-7C are views corresponding to FIGS. 6A-6C, with the feeding device biased to one side. 
     FIGS. 8A-8C are views corresponding to FIGS. 6A-6C, with the feeding device biased to a side opposite that shown in FIGS. 7A-7C. 
     FIG. 9 is a top view of an end-rounding device according to one embodiment of the present invention. 
     FIG. 9A is a perspective view of the end-rounding device of FIG.  9 . 
     FIG. 10 is a side cut-away view of the end-rounding device of FIG.  9 . 
     FIG. 11 is a top view of a stationary clamping device according to one embodiment of the present invention. 
     FIG. 12 is a top view of a moldbar according to one embodiment of the invention. 
     FIG. 13 is a perspective view of one toothbrush cavity of the moldbar of FIG.  12 . 
     FIG. 14 is a front view of the tufting machine shown in FIG. 4, showing movement of various elements of the tufting machine. 
     FIG. 15 is a front view of the tufting machine shown in FIG. 4, showing movement of various elements of the tufting machine. 
     FIG. 16 is a front view of the tufting machine shown in FIG. 4, showing movement of various elements of the tufting machine. 
     FIG. 17A is a side cut-away view of a portion of the moldbar of FIG. 12 showing the bristles being inserted. 
     FIG. 17B is a side cut-away view of a portion of the moldbar of FIG. 12 showing the bristles being inserted. 
     FIG. 18 is a perspective view of the moldbar of FIG. 12 with bristles inserted. 
     FIG. 19 is a perspective view of the moldbar of FIG. 18 with a blade engaged and the bristles cut. 
     FIG. 20 is a perspective view of the moldbar of FIG. 19 with the blade disengaged and the bristles cut. 
     FIG. 21 is a side cut-away view of the moldbar of FIG. 12 showing the bristles within the moldbar and a toe-tuft being inserted. 
     FIG. 22 is a side cut-away view of the moldbar of FIG. 12 engaged with the rest of a toothbrush mold to form a toothbrush handle around the bristles. 
     FIG. 23 is a side cut-away view of the toothbrush of FIG.  1 . 
     FIGS. 24A and 24B are side views of a rope of bristles looping on itself. 
     FIG. 25 is a perspective view of a tensioning device suitable for use in the tufting machine shown in FIG.  4 . 
    
    
     DETAILED DESCRIPTION 
     Preferred processes for feeding and end-rounding filaments to tuft an oral brush generally include the following steps, which will be discussed briefly now, and explained in further detail below. The processes described below are suitable for the manufacture of a toothbrush  10  having tufts  12 ,  14 ,  16  that are of different lengths and extend at different angles, e.g., as shown in FIG.  1 . The arrangement of the tufts will be referred to herein as the tuft geometry. The tufts are held in a moldbar  28  (FIGS.  12  and  13 ), which has the desired tuft geometry and is used as a part of an injection-molding cavity to form a handle  18  around the tufts. 
     Generally referring to FIGS. 2 and 4, groups of filaments of bristle material are provided in a plurality of ropes  22 , each rope  22  corresponding in diameter and number of filaments to a tuft on a finished toothbrush. The free ends  24  of the ropes  22  enter a tufting machine  20  (step  110 , FIG.  2 ). After the initial threading step, the ropes  22  are continuously fed from the spool  26  through the tufting machine  20  (step  111 , FIG.  2 ). The free ends  24  of the ropes  22  are end-rounded (FIG.  15  and step  112 , FIG. 2) before being advanced into the moldbar  28  (FIG.  16  and step  114 , FIG.  2 ). Once the free ends  24  of the ropes  22  are within the moldbar  28 , the bristles are cut to length (FIGS. 18-19 and step  116 , FIG.  2 ). Each moldbar  28  is configured to produce multiple toothbrushes (FIG.  12 ), so this process is continued (step  117 , FIG. 2) until the entire moldbar  28  is full of bristles. Once the moldbar  28  has been filled with bristles, the moldbar  28  is advanced into an injection molding station where the handle  18  is formed around the bristles (FIG.  22  and step  118 , FIG.  2 ). 
     Prior to introduction into the moldbar  28 , the free ends  24  of the filaments in ropes  22  are end-rounded within the tufting machine  20  by an end-rounding device  200  (FIG.  9 ). The end-rounding device  200  of the present invention is low-profile and air driven, which allows the free ends  24  of the ropes  22  to be end-rounded within the tufting machine  20 . Conventional electric motor driven end-rounding devices would not easily fit within the tufting machine, and tend to be too heavy to move into and out of engagement with the free ends  24  of the ropes  22  quickly. The air-driven end-rounder  200  allows for a smaller machine, thereby saving valuable floor space. 
     Referring to FIG. 4, the ropes  22  are advanced through the tufting machine  20 , towards the moldbar  28 , by a feeding device  30 . Feeding device  30  is constructed to selectively advance the individual ropes  22  to different depths within the moldbar  28  corresponding to the tuft lengths of tufts  12 ,  14 ,  16  in FIG. 1, as will be discussed below. This selective advancement capability results in efficient and economical manufacture of toothbrushes  10  having tufts of different lengths. The tufting machine  20  can include any desired number of feeding devices  30 ; two are shown in FIG.  4 . Multiple feeding devices  30  can be oriented at different angles relative to the vertical, as shown in FIG. 4, to allow the ropes  22  to be advanced into the moldbar  28  at opposing angles, resulting in a finished toothbrush  10  with tufts that extend at different angles, as shown in FIG.  1 . The selective advancement capability also results in a smaller tufting machine, which allows the process to occur closer to the moldbar thereby minimizing tuft damage or feeding problems. 
     The tufting machine  20  also includes a manifold  60  into which the ropes  22  pass after they have passed through the feeding devices  30 . The manifold  60  has guideways  51  that keep the ropes  22  on a path directly to the moldbar  28 . Within the manifold  60  is a stationary clamping device  59 , which works with the feeding devices  30  and the blade  70 , as will be described fully below. Also movably mounted on the manifold  60  is the end-rounding device  200 , which can be moved into and out of engagement with the free ends  24  of the ropes  22 . 
     Referring to FIGS. 12,  13 ,  17 A and  17 B, the tufting machine  20  advances the free ends  24  of each of the ropes  22  into blind holes  82 ,  84 ,  86  in moldbar  28 . Each of the blind holes is shaped and sized to accept a single rope  22  in a close-fitting engagement. Each of the holes  82 ,  84 ,  86  is machined to a depth and at an angle that will provide the desired tuft geometry. Each hole  82 ,  84 ,  86  is filled by the tufting machine  20 , with the finished free end  24  of each rope  22  being inserted to the proper depth and at the proper angle. 
     After the ropes have been advanced fully into the moldbar  28 , i.e., after the free end  24  of each of the ropes  22  contacts the bottom  78 ,  79  of each blind hole  82 ,  84 ,  86  of the moldbar  28 , the filaments are clamped by a stationary clamping device  59  and cut so that a portion of each filament extends above the top surface  76  of the moldbar  28 . This portion will extend into the mold cavity  80  (see FIG.  22 ), and thus will be embedded in the injection molded toothbrush body  18 . The end rounded free ends  24  of the filaments will be the free or working ends of the bristles  12 ,  14 ,  16  in the finished toothbrush  10  (FIG.  1 ). Each moldbar  28  is configured to produce multiple toothbrushes, as shown in FIG.  12 . Therefore, after cutting, the moldbar  28  is either indexed to the next set of unfilled blind holes  82 ,  84 ,  86 , or, if the moldbar  28  is full, removed and transferred directly to an injection-molding machine (not shown), where it is used to define part of the molding cavity  80  or to an intermediate step, such as fusing the filaments together to form an anchor. 
     The ropes  22  of filaments are not cut to tuft length until the end-rounded free ends  24  have been fully advanced into the moldbar  28 . Feeding continuous filaments, rather than cut tufts, into the moldbar  28  holes eliminates the sometimes problematic picking, tuft-transfer and moldbar-filling steps involved in filling a moldbar  28  with bristles, and as a result generally also reduces manufacturing problems. 
     The steps of this process, and the machine components used to perform each step, will now be discussed in further detail. 
     The Feeding Device 
     As discussed above, the feeding device  30  selectively clamps the ropes  22  that pass through the feeding device  30 , and advances the clamped ropes  22  towards the moldbar  28 . 
     Referring to FIGS. 6A-6C, the feeding device  30  includes a pneumatic cylinder  32  with a piston  34 . As shown by arrow A in FIG. 4, the feeding device  30  moves in a generally vertical direction relative to the frame  48  along a slide  38 , and is moved by a cam  36 . A motor  44  connected to the cam  36  by a leadscrew  40  and a leadscrew nut  42  drives the cam  36 . 
     Referring to FIGS. 6A-6C, the feeding device  30  has guideway holes  50  through which the ropes  22  pass. These guideway holes  50  pass through the feeding device  30 , including both the cylinder  32  and the piston  34 , and communicates with guideway holes  51  that extend through the manifold  60 . Thus, guideway holes  50  and  51  define a continuous pathway from the top of the tufting machine  20  to the moldbar  28 . The guideway holes  50  are shaped like the final shape of the tufts of bristles  12 ,  14  that will be molded into the toothbrush handle  18 . Guideway holes  50  guide the ropes  22  through the tufting machine  20 , and provide selective clamping as will be described below. 
     The piston  34  of the feeding device  30  is capable of being biased to the center, as shown in FIGS. 6A-6C, to the left, as shown in FIGS. 7A-7C, or to the right, as shown in FIGS. 8A-8C. When the piston  34  is biased to the center, as shown in FIGS. 6A-6C, the guideway holes  50  are perfectly aligned and do not grip the ropes  22 . Certain guideway holes  52  within the piston  34  are elongated holes to allow selectivity when gripping the ropes  22 . When the piston  34  is biased to the left approximately 0.020 inches, as shown in FIGS. 7A-7C, the guideway holes  50  and elongated guideway holes  52  misalign at all locations and grip all the ropes  22  passing through. When the piston  34  is biased to the right approximately 0.020 inches, as shown in FIGS. 8A-8C, only the non-elongated guideway holes  50  misalign, allowing the feeding device  30  to grip only the ropes  22  that pass through the misaligned holes. 
     As will be discussed in detail below, the selectivity provided by elongated holes  52  allows the feeding device  30  to move certain ropes  22  further through the tufting machine  20  than others, thereby allowing tufts of varying lengths to be fed into the moldbar  28  using a single feeding device  30 . One advantage of a single feeding device  30  that selectively moves certain ropes  22  is compact size. Without the selectivity of the present feeding device  30 , two gripping devices would be needed to accomplish the same task, thereby increasing the size of the tufting machine  20  and the complexity of threading the ropes  22  through the tufting machine  20 . Further, the small size of feeding device  30  allows two feeding devices  30  to be mounted at different angles to each other (as shown in FIG.  4 ), thereby facilitating easy manufacture of toothbrushes with tufts of bristles at opposing angles, such as the toothbrush  10  shown in FIG.  1 . 
     The Manifold 
     As described above, the manifold  60  is the part of the machine between the feeding devices  30  and the moldbar  28  that keeps the ropes  22  on a path towards the moldbar  28  and supports the end rounding device  200  and a stationary clamping device  59 . 
     Referring to FIGS. 4 and 5, the manifold  60  is below the feeding device  30 . Fitted into the manifold  60  is a stationary clamping device  59 , which is similar to the feeding device  30  in that it allows for selective gripping by using elongated holes. The stationary clamping device  59  consists of a plate  64  (FIG. 11) movably mounted to the manifold and a piston  62  connected to the plate  64  to move the plate  64  between three positions. The guideways  51  that run through the manifold  60  also run through the plate  64 , and are aligned precisely when the piston  62  is in a centered position. When pressure is applied to one end of the piston  62 , all guideways in the plate  64  misalign thereby clamping all the ropes  22 . When pressure is applied to the other end of the piston  62 , only non-elongated guideways in the plate  64  misalign, thereby clamping only selected ropes  22 . 
     The manifold  60  also supports an end-rounding device  200 . The end-rounding device  200  is described more fully below. The end-rounding device  200  can be moved into a position below the guideways  51  in the manifold  60  so the free ends  24  of the ropes  22  can be put into contact with the end-rounding device  200  (FIGS.  14  and  15 ). The manifold  60  supports the end-rounding device  200  in T-slots (not shown) in the bottom of the manifold  66 , which allow the end-rounding device  200  to move along the bottom of the manifold  66 . 
     The End-Rounding Device 
     The end-rounding device  200 , shown in detail in FIGS. 9,  9 A and  10 , has a relatively low profile and is relatively light and compact, allowing the end-rounding device to be easily moved transversely into and out of engagement with the free ends of the filaments. Because the end-rounding device can be easily moved in this manner, during the entire tufting process the filaments need only be advanced axially, and do not need to be transported out of their plane of axial movement to engage the end-rounding device. Typically, the end-rounding device is less than 2 inches in height (dimension H in FIG.  10 ), more preferably less than 1.5 inches, and weighs less than 5 pounds. 
     The end-rounding device also has a continually varying elliptical grinding path, described below, that allows the sanding surface of the end-rounding device to attack the free ends  24  of the individual filaments from all sides, resulting in uniform, high quality end-rounding with no damage to the individual filaments. 
     The end-rounding device  200  includes a sanding wheel  202  that is fixed to a planet gear  204 A that extends through a planet carrier  210 . A second planet gear  204 B also extends through the planet carrier  210  to balance the system. The planet gears  204 A,  204 B engage a stationary ring gear  208  mounted below the planet carrier, as described below, which causes the planet gears to rotate as the planet carrier rotates. 
     The rotation of the planet carrier  210  is driven by air, and the rotation of the planet carrier drives the rotation of the planet gear  204 A, due to the engagement of the planet gears with the stationary ring gear  208 . Thus, the sanding wheel  202  is entirely air driven, contributing to the low profile and compact size of the end-rounding device. 
     The planet carrier  210  is a turbine that drives the end-rounding device. The planet carrier  210  is rotated about its axis (arrow A, FIG. 9) by airflow against vanes  300  (FIG. 9A) which are arranged at spaced intervals around the periphery of the planet carrier. The vanes  300  are configured to allow compressed air to rotate the planet carrier  210  efficiently and at high rates of revolution, e.g., at least 5,000 rpm, more preferably at least 10,000 rpm. The planet carrier  210  sits within a radial/thrust bearing  214 , which includes an air manifold  216  to deliver the compressed air to the planet carrier  210  through openings  304  (FIG.  9 A). 
     As discussed above, when the planet carrier  210  rotates, the planet gears  204 A,  204 B engage stationary ring gear  208 . Stationary ring gear  208  is press-fit into the radial/thrust bearing  214  so that it does not move when engaged by the planet gears. As a result, this engagement causes the planet gears  204 A,  204 B to rotate about their axes in a direction (arrows B, FIG. 9) opposite to the direction of rotation of the planet carrier  210 . Stationary ring gear  208  and planet gears  204 A,  204 B together define a planetary drive mechanism  206 , which drives the sanding wheel  202  in a deviating elliptical orbit discussed below. 
     Because the planet carrier  210  acts as a drive mechanism and as an air bearing (replacing a ball bearing that would be required in a motor-driven end-rounding device), the end rounding device  200  requires relatively few parts, further contributing to its low profile and compact design. Moreover, the use of an air as a lubricant allows very high rates of revolution, as discussed above, without requiring liquid lubrication that could contaminate the filaments. Further, the planet carrier  210  provides a barrier between the sanding wheel  202  and the planetary drive mechanism  206 , thereby preventing any grinding dust from contaminating the planetary drive mechanism that could cause premature wear in the gears. 
     The preferred method of end-rounding the free ends of the filaments is to attack the filaments from all sides. However, if the number of teeth on the planet gear  204  were exactly half the number of teeth on the stationary ring gear  208 , any point on the pitch circle C of the planet gear would inscribe a straight line when the planet carrier is rotated, the line being a diameter of the stationary ring gear  208 . Each revolution of the planet carrier  210  would move the same point on the pitch circle continually along the same straight line. This is known as Cardanic Motion. This straight line would attack the filaments from only two sides. However, the path of the straight line may be deviated slightly by setting the tooth ratio of the stationary ring gear  208  to the planet gear  204  at slightly higher than 2:1, generally by a few teeth. With this tooth ratio, when planet carrier  210  is rotated, any point on the pitch circle C (FIG. 9) of the planet gear  204  will inscribe a straight line that slightly changes direction with every rotation of the planet gear  204 . This deviating straight line of a point on the sanding wheel allows the sanding wheel to attack the free ends of the filaments from all sides, resulting in uniform end-rounding. 
     If the sanding wheel  202  is mounted on the planet gear  204  so that the center of the sanding wheel lies on the pitch circle C, the sanding wheel comes to a momentary halt at the end of its stroke and tends to reverse direction along nearly the same path; i.e. the deviating straight line described above. This generally causes the filaments that are being sanded to be bent over in a cantilever fashion by the sanding wheel  202  during the “in” stroke, and may cause the filaments to be twisted out of plane when the sanding wheel  202  reverses direction. This action may damage the filaments and/or may not produce well-rounded ends  24 . Thus, it is preferred that the sanding wheel  202  be mounted with its center affixed to a point internal to the pitch circle C, so that the sanding wheel  202  will inscribe an ellipse rather than a straight line. When the sanding wheel  202  approaches its apogee it begins to rotate the filaments, achieving the opposite bend more or less gradually instead of suddenly. The slight change in direction of the inscribed line, as described above, will change the direction of the major diameter of the ellipse, resulting in a continual change in the direction of the overall elliptical path of the sanding wheel. Combining both the deviating straight line, which allows the filaments to be attacked from all sides, and the elliptical path, which prevents the filaments from bending in a cantilever fashion, provides well-rounded filaments. 
     It can be appreciated that the sanding wheel  202  may also be mounted such that its center point is outside the pitch circle, which will also allow an elliptical path to be achieved. Further, it should be understood that only certain points on the sanding wheel inscribe the deviating elliptical path. All other points on the sanding wheel with inscribe varying elliptical patterns, a small set that will degenerate into a straight line and a small set that will inscribe a circle. However, the majority inscribes some fashion of an elliptical pattern, and filaments end-rounded utilizing the described device are well rounded. 
     The Feeding Process 
     Referring to FIGS. 4-5, the ropes  22  are fed from spools  26  into the tufting machine  20 . The ropes  22  are threaded through the feeding device  30  and manifold  60  via guideway holes  50  (see FIG. 6A) and  51 , which generally keeps the ropes  22  on trajectory toward the moldbar  28 . 
     During the initial threading, the ropes  22  are fed into the tufting machine  20  to a point just above the bottom of the manifold  66 . Referring to FIGS. 3A-3B, the ropes  22  are advanced through the tufting machine  20  by the feeding device  30 , in cooperation with the stationary clamping device  59 . Describing the sequence starting with the ropes  22  just above the bottom of the manifold  66 , the feeding device  30  is biased to the left to clamp all the ropes  22  (step  120 , FIG.  3 A). The end-rounding device  200  is moved into position below the guideways  51  of the manifold  60  (FIG.  14 )(step  122 , FIG.  3 A). The feeding device  30  is advanced to bring the free ends  24  of the ropes  22  into contact with the sanding wheel  202  of the end-rounding device  200  (FIG.  15 )(step  124 , FIG.  3 A), and the stationary clamping device  59  is biased to clamp all the ropes  22 . Once the free ends  24  of the ropes  22  have been sufficiently rounded, the stationary clamping device  59  is biased to unclamp all the ropes  22 , the feeding device  30  withdraws the ropes  22  from the sanding wheel  202  to a point just above the bottom of the manifold  66  and the end-rounder  200  is moved back to its original position (step  126 , FIG.  3 A). The moldbar  28  is moved upward into engagement with the bottom of the manifold  66  (step  127 , FIG.  3 A). 
     The piston  34  of the feeding device  30  continues to be biased to clamp all the ropes  22  passing through (biased to the left as shown in FIGS.  7 A- 7 C), and the stationary clamping device  59  is biased to allow the ropes  22  to move freely. The feeding device  30  is moved downward, advancing the ropes  22  forward toward the moldbar  28  (FIG.  16 )(step  128 , FIG.  3 A). The distance D 1  moved corresponds to a point just above the bottom of the manifold  66  to the bottom  78  of the more shallow blind holes  82 ,  84  of the moldbar  22 , which correspond to shorter tufts  12  (FIG.  1 ), thereby advancing the free end  24  of the ropes  22  to the bottom  78  of those more shallow blind holes  82 ,  84  in the moldbar  28  (FIG.  17 A). 
     The piston  64  of the stationary clamping device  59  is then biased in the opposite direction to clamp all the ropes  22 , and the piston  34  of the feeding device  30  is biased to the center (FIGS. 6A-C) to unclamp all the ropes  22  (step  130 , FIG.  3 A). The feeding device  30  then moves backwards along the ropes  22  a distance equal to the difference in length between the shorter bristles  12  and longer tufts  14  (FIG. 1) of the final product, i.e. distance D 2  in FIG. 17A (step  132 , FIG.  3 A). The stationary clamping device  59  prevents the ropes  22  from pulling out of the moldbar  28  by friction between the feeding device  30  and the ropes  22  as the feeding device  30  moves upward. 
     The piston  34  of the feeding device  30  is next biased to the right to selectively clamp the ropes  22  that will be longer bristles  14  (FIG. 1) in the final product (as shown in FIGS.  8 A-C), and the stationary clamping device  59  is biased to clamp the ropes  22  that have been advanced to the bottom of the shallow holes (step  134 , FIG.  3 A). The feeding device  30  then moves downward a distance D 2 , thereby advancing the rest of the ropes  22  to the bottom  79  of the deeper blind holes  86  in the moldbar  28  (FIG.  17 B)(step  136 , FIG.  3 A). 
     The stationary clamping device  59  then clamps all the ropes  22  and feeding devices  30  unclamp all the ropes  22  (step  138 , FIG.  3 A). The feeding devices  30  are then moved upward approximately 0.10 inches (step  140 , FIG.  3 B). The feeding devices  30  then clamp all the ropes  22  and the stationary clamping device  59  unclamps all the ropes  22  (step  142  FIG.  3 B). The feeding devices  30  and the moldbar  28  simultaneously move downward approximately 0.10 inches (step  144 , FIG.  3 B). 
     The stationary clamping device  59  is biased then to clamp all of the ropes  22  and the bristles are cut from the ropes  22  by a blade  70 , discussed in detail below (step  146 , FIG.  3 B). The blade  70  cuts the ropes  22  flush with the bottom of the manifold  66 . Next, the piston  34  of the feeding device  30  is biased to unclamp all the ropes  22  (FIGS. 7A-C) and the stationary clamping device  59  is biased to clamp all the ropes  22 . The feeding device  30  moves upwards along the ropes  22  to give the feeding devices  30  about ½ inch slack to feed the ropes  22  during the next cycle (FIG.  14 )(step  148 , FIG.  3 B). If the moldbar  28  is not completely full (step  150 , FIG.  3 B), the moldbar  28  is then advanced to allow a new, empty section to be aligned with the guideways  50  of the manifold  60  (step  152 , FIG.  3 B), and the process described above is repeated. If the moldbar  28  is completely full of bristles, the moldbar  28  is removed and a new moldbar is inserted into the tufting machine  20  (step  150 , FIG.  3 B). 
     It should be understood that the steps described above are the same for both feeding devices  30 , when two are used as shown in FIG.  4  and that the two feeding devices generally perform the steps simultaneously. Also, only a single stationary clamping device  59  is needed to cooperate with two feeding devices  30 . 
     Cutting the Filaments to Bristle Length 
     Referring to FIGS. 18-20, the ropes  22  pass out of the guideways  51  in the manifold  60  and into the moldbar  28 . A blade  70  is movably mounted on the bottom of the manifold  66 , and can move from a position out of engagement to a position into engagement with the ropes  22  that pass out of the guideways  51  in the manifold  60 . 
     The tufts  12 ,  14  are cut from the ropes  22  by blade  70 . The moldbar  28  and the feeding devices  30  simultaneously move downward approximately 0.10 inches to allow the blade  70  to pass freely between the moldbar  28  and the bottom of the manifold  66 , as well as allowing the finished tufts in the moldbar  28  to protrude above the top surface  76  of the moldbar  28 . The stationary clamping device  59  is biased to clamp all the ropes  22 . The blade  70  engages, cutting the ropes  22  flush with the bottom of the manifold  66 , and then disengages, allowing the moldbar  28  to be indexed and new ropes  22  to be inserted. The ends protruding from the moldbar  28  are anchored into the toothbrush  10  when the toothbrush handle  18  is injection molded around them. The free ends  24  within the moldbar  28  become the working ends of the bristles in the finished toothbrush  10  (FIG.  1 ). 
     Repeating the Tufting Process 
     After the tufts  12 ,  14 ,  16  have been cut to length, as discussed above, the moldbar  28  is indexed to align an empty section of the moldbar  28  with the guideways  51  in the manifold  60 . The above process is continued until all the moldbar  28  sections have been loaded with bristles. The moldbar  28  is then removed from the tufting machine  20 , and replaced with a new moldbar  28 . 
     The filled moldbar  28  may then be transferred to another filling station to receive more bristles (step  154 , FIG.  3 B), such as a toe-tuft  16 , as shown in FIG.  21 . Once the moldbar is completely filled, the moldbar  28  is transferred to an injection-molding machine (step  156 , FIG.  3 B), where it defines part of a mold cavity  80 , as shown in FIG.  22 . Before going to the injection-molding machine, the tufts could be fused together by a heating step, which also produces an anchor to be formed on the ends of the bristles, as is well known in the art. Resin is injected into the mold cavity  80  and a handle  18  is formed around the portions of tufts  12 ,  14 ,  16  that extend into the mold cavity  80 , anchoring the bristles firmly within the handle  18  (FIG.  23 )(step  158 , FIG.  3 B). The finished toothbrush  10  is then sent to a packaging station (step  160 , FIG.  3 B). 
     The Tensioning Device 
     Referring to FIGS. 24A and 24B, one problem may occur between the spools  26  and the tufting machine  20 . Since the ropes  22  are advanced at different lengths, the slack between the spools  26  and tufting machine  20  will vary from one rope  22  to the next and the variation will increase with each cycle of the tufting machine  20 . Eventually, the slack will cause a loop  88  in the ropes  22  (FIG. 24A) that will move out of plane and turn on itself (FIG.  24 B), eventually causing a snag or break. Putting each rope  22  through a separate tension device would typically be expensive and difficult to thread. Further, individual tension devices could have a problem compensating for the increasingly varied lengths. 
     To provide uniform tensioning, the present invention utilizes a tensioning device  90 , shown in FIG.  25 . The ropes  22  are threaded between two parallel plates  92  and  94  through guides  96  and  96 A. Guides  96  and  96 A are generally substantially colinear. The two parallel plates  92 ,  94  are preferably made of a transparent material, such as glass or polycarbonate, to allow the operator to observe the ropes  22  within the tensioning device  90 . The parallel plates  92 ,  94  are spaced so as to allow the ropes  22  to move towards the tufting machine  20 , while reducing the tendency of the ropes to move out of plane and flip on themselves. Generally, the spacing of the plates is from about 2 to 5 mm. 
     Side walls  98  and  98 A connect the two parallel plates  92 ,  94 , and can either run the entire height of the parallel plates, as shown in FIG. 25, or for a portion of the height of the parallel plates  92 ,  94 . Side walls  98  and  98 A are typically rubber gaskets, which both space and connect the parallel plates  92 ,  94 . The guides  96 ,  96 A are holes within the side walls  98 ,  98 A, located generally toward the top of the parallel plates  92 ,  94 . 
     A top wall  99  and a bottom wall  99 A also connect the parallel plates. The top wall  99  and bottom wall  99 A may be as long as the parallel plates  92 ,  94 , as shown in FIG. 25, or a portion of the length. Top wall  99  and bottom wall  99 A are typically rubber gaskets, which both space and connect the parallel plates  92 ,  94 . The top wall  99  will have one or a series of openings through which a fluid  95 , e.g., compressed air or water, is passed. The fluid  95  will pass over the ropes  22 , keeping tension on each individual rope  22  independent of the rope&#39;s length. The fluid  95  will then pass through openings (not shown) in the bottom wall  99 A, or around the bottom wall  99 A if the bottom wall is of a length less than the entire length of the parallel plates  92 ,  94 . Generally, the fluid should flow in a direction substantially perpendicular to a line drawn between guides  96  and  96 A, preferably within ±5 degrees of perpendicular. 
     The tensioning device  90  is an easy and effective way to keep tension on each rope  22  and thereby prevent snagging. If water is used as the fluid  95 , the tensioning device can also serve the function of annealing the filaments if they have not yet been annealed during manufacturing, e.g., if the filaments are being fed directly from a spinneret or extruder rather than from a spool. 
     Other embodiments are within the scope of the following claims. For example, the methods and devices of the invention are also suitable to form other types of brushes, not just toothbrushes. Moreover, while the end-rounding device is described as being air driven, any type of compressed gas may be used. Also, the device described may be adapted to be used independent of a manufacturing machine. Accordingly, other embodiments are within the scope of the following claims.