Abstract:
The invention is directed to a device for the manufacture of bristle products, in particular toothbrushes, with a feed unit for precut lengths of upstanding bristles arranged loosely in a supply duct, the bristles being routed directly to a picker segment picking up the bristles. The device includes a driven conveyor at the end of the supply duct close to the picker segment, or a further processing station.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    This application claims the benefit of German application serial number 101 43 674.2 filed Sep. 6, 2001.  
         TECHNICAL FIELD  
         [0002]    This invention relates to methods and devices for the manufacture of bristle products, such as toothbrushes.  
         BACKGROUND  
         [0003]    Devices for the manufacture of bristle products, such as toothbrushes, are well known.  
           [0004]    Thus, for example, U.S. Pat. No. 4,360,236 describes a double fiber magazine for a brush manufacturing machine, comprising two magazines immovably connected to each other. The magazines are located opposite a picker or bundle plucker. According to this disclosure, each magazine is provided with a separating device and pressing components for pressing the fibers towards the bundle plucker. Moreover, provision is made for a device which alternately loads the fibers beyond the reach of the bundle plucker into one of the two fiber magazines. The double fiber magazine described in U.S. Pat. No. 4,360,236 finds application, for example, in the manufacture of toothbrushes comprising bristles of different color or different material.  
           [0005]    U.S. Pat. No. 5,518,301 describes a method and a device for supplying fibers to a filling tool in a brush manufacturing machine. For each operating cycle, the method comprises the following steps: transporting a bundle of fibers from a selected fiber supply duct to a filling tool by means of a bundle take-up device which cooperates with at least two fiber supply ducts; using, for the selective supply of fibers, movable closing devices which cooperate with supply ends of the fiber supply ducts and ensure, by their movement, that fibers can only be taken from one fiber supply duct at a time by the bundle take-up device. The closing devices are mounted on a common support for simultaneous operation during each operating cycle.  
           [0006]    DE 26 43 222 A1 also describes a method and a device for manufacturing brushes. In this specification, a brush manufacturing machine includes a bristle magazine which cooperates with one or several tufting devices. The brush manufacturing machine also includes a feed device for feeding bundled bristles to the magazine, and an opening device for opening the wraps holding the bristle bundles together. The feeding device is located in the transfer area on the magazine input side and includes a conveyor with holding devices for bristle bundles, which is constructed as a belt conveyor or as a chain in loop form.  
           [0007]    DE 38 06 160 A1 discloses a pre-processing or work feeding machine for bristles in which the fibers are fed in the form of bundled or wrapped bristle clusters. In this method the wrap of the bristle clusters is opened automatically, and the fibers undergo a cleaning and orientation operation before being fed to the fiber supply ducts of a brush manufacturing machine. For transportation, the filaments are held clamped between flat belts, being thus moved forward in simple manner, in batches in conformity with the operating cycle.  
           [0008]    It is a disadvantage of the known methods and constructions of the known filament supply ducts that zones occur in which a continuous filament flow is not allowed to develop. These zones, also referred to as dead zones, have an adverse effect on process safety and product quality.  
           [0009]    Finally, U.S. Pat. No. 3,367,719 discloses a device for the manufacture of bristle products of the above-described type wherein a chain sprocket conveying device is provided at one side of the filament package.  
         SUMMARY  
         [0010]    The invention features methods and devices for manufacturing bristle products economically with a high level of process safety and product quality.  
           [0011]    In one aspect, the invention features a device for the manufacture of bristle products, in particular toothbrushes, including a feed unit including a supply duct configured to receive a plurality of precut lengths of upstanding bristles; and  
           [0012]    a picker segment for picking up the bristles and combining them into tufts;  
           [0013]    the feed unit further including a driven conveying device configured to deliver the bristles from the supply duct to the picker segment, the driven conveying device that including opposite pressure surfaces, with the bristles being arranged therebetween.  
           [0014]    Because clusters of bristles are conveyed actively by opposite pressure surfaces provided at both sides of the cluster of bristles, dead zones in which no continuous flow of bristles takes place are avoided. Effects known under the term “arching” or “bridging” generally will not occur because the bristles are fed actively from both sides. “Arching” or “bridging” is understood to mean an apparent interlocking of the bristle clusters, which impedes solid body flow. The pressure surfaces form a laterally bordering bristle track, between which the two sides of the bristle cluster abut by means of the bearing pressure formed by the pressure surfaces. In this way, a safe and steady conveyance of the bristles is achieved and, here, both pressure surfaces run synchronously at the same velocity.  
           [0015]    Furthermore, active filament feed expedites the removal of interferences occurring in the filament bed, generally resulting in an increased product quality. This means that sections in the filament supply duct in which filaments have lost their upright orientation due to external influences are pushed out of the filament supply duct more quickly. This results in a reduced susceptibility to trouble and enhances process safety. In addition, it enables the filaments to be picked up symmetrically from the middle of the duct. To achieve this, it is preferred that the opposing conveying devices be arranged symmetrically at the duct. A higher constancy in the number of filaments flowing into the recesses of the picker segment on each operating cycle is also generally achieved.  
           [0016]    Another advantageous effect is a reduced dependence upon the filament finish level. This means that the supply of bristle clusters is independent of the filament manufacturing process and the filament type while process safety is maintained at a consistently high level. This also enables processing of filaments proceeding at a very slow rate. This becomes apparent, for example, from the smooth processing of particularly fine filaments with a diameter less than, for instance, 0.12 mm, which corresponds to about 0.005 inch.  
           [0017]    With the device of the present invention it is also possible to provide the requisite number of filaments per picker stroke. The use of a driven conveying device designated as active feed may be directly incorporated in the tuft forming process.  
           [0018]    The terms “picker segment” or “picker tooling” refer to a tool for picking up the tufts and subsequently transferring them to their destination on the bristle carrier.  
           [0019]    The pressure surfaces described above may include flat or toothed belts. The flat or toothed belts may be fabricated, for example, from a fabric-reinforced elastomer plastic. They may have a roughened or structured surface.  
           [0020]    The longitudinal direction of the bristles may extend at a right angle to the direction of motion of the pressure surfaces. In this case, a cluster-like string of bristles may extend through the duct formed by the two opposed pressure surfaces. By this, individual tufts can be made in one draw in the picker segment.  
           [0021]    Alternatively, individual bristles may run in the direction of motion of the conveying device. In this case, the duct or gap formed between the pressure surfaces is generally of the same size as the thickness of the bristles, so as to transport them separately in series or side-by-side.  
           [0022]    The driven conveying device may include pressure elements for the application of transfer forces to the circumferential surface of outer lying bristles. For example, two opposed movable pressure elements may be provided, between which the stream of filament clusters is pushed through by appropriate forward or tangential forces.  
           [0023]    The conveying device may include opposite gears or structural wheels having grooves adapted to receive the bristles therebetween. The conveying device may be equipped with two or several wheels made of metal or plastics.  
           [0024]    The device may be configured to be synchronized with a subsequent sequence of operations. In this case, the filaments on both sides of the conveying device are generally transported steadily and synchronously, thus avoiding relative displacements of the individual bristles with respect to each other.  
           [0025]    The device may be configured for the manufacture of filament strands. In this arrangement the exit opening of the conveying device may be of the adjustable type.  
           [0026]    The device of the present invention is particularly suitable for processing of special filaments, since these are generally transported steadily in spite of different surfaces, cross-sections and work materials.  
           [0027]    Further advantageous embodiments and aspects of the present invention will be described in the following with reference to the accompanying drawings.  
       
    
    
     DESCRIPTION OF DRAWINGS  
       [0028]    [0028]FIG. 1 is a schematic sectional view of an active feed unit illustrating a first embodiment of the present invention; and  
         [0029]    [0029]FIG. 2 is a perspective view of an active feed unit illustrating a second embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0030]    [0030]FIG. 1 shows in a schematic sectional view a first embodiment of an active feed unit  1 , i.e., a driven bristle conveying device, including an upper conveyor belt  2  and a lower conveyor belt  8 , each constructed as a driven flat belt of elastomer plastic.  
         [0031]    The upper conveyor belt  2  and the lower conveyor belt  8  are arranged in mirror symmetry about an axis of symmetry  9 . The architecture of the conveyor belts  2 ,  8  is therefore described only once.  
         [0032]    The symmetrical conveyor belts  2 ,  8  each include one drive wheel  3  and four deflection pulleys  5 . The conveyor belt  2 ,  8  is wrapped around the deflection pulleys  5  in such fashion that a straight-line tensioned pressure surface  6  parallel to the axis of symmetry  9  is produced between the two deflection pulleys  5 . Arranged in spaced relation to the pressure surface  6  and the line of symmetry  9  is the drive wheel  3  around which the conveyor belt  2 ,  8  is wrapped for nearly half the wheel circumference. Adjacent to the drive wheel  3  is another deflection pulley  5  which bears against the conveyor belt  2 ,  8  from outside, hence acting as a pressure roller. Next to this pressure roller is another deflection pulley  5 , which deflects the conveyor belt  2 ,  8  in the direction of the pressure surface  6 .  
         [0033]    The upper conveyor belt  2  and the lower conveyor belt  8  serve the function of transferring precut lengths of upstanding bristles  10 , also referred to as filaments or strands, which are arranged loosely in a supply duct  21 , without any damage occurring. The tangential forces applied by the pressure surfaces  6 ,  6  act to move the plural bristles  10  along the line of symmetry  9  in the direction of arrow A, producing a track  20  of bristles with the pressure surfaces  6  as its lateral boundaries. In FIG. 1, the bristles  10  extend at a right angle to the direction of arrow A, so that in FIG. 1 only the surfaces of the cut ends of the bristles  10  are visible which are depicted as points but which, in reality, lie closely to each other.  
         [0034]    According to FIG. 1, at the end of the pressure surface  6  the bristles  10  approach an exit opening  7  of a predetermined diameter. Located at this opening is a picker segment  22 , which is equipped with cavities  24  and combines the bristles  10  into tufts  25 . For further processing, the bristles  10  are taken, for example, to mold bars (not shown) where their ends are sprayed with plastic so as to form a complete toothbrush head.  
         [0035]    In another embodiment (not shown), only individual bristles  10  pass the bristle track  20 , and thus the bristle track  20  is not wider than the diameter of the individual bristles  10  and the individual bristles  10  are transported in series through the very small bristle track  20 . At the end of bristle track  20 , the bristles  10  are conveyed in a recess for forming a tuft. When a recess is filled, it will be shifted sideways and the next recess comes up to the level of the very small bristle track  20  and can be filled with bristles  10 .  
         [0036]    [0036]FIG. 2 shows a perspective view of a second embodiment of an active feed unit  15 . The feed unit  15  of this embodiment comprises a base plate  11  and a cover plate  12 . The base plate  11  and the cover plate  12  are made from solid, machined metal. Rotatably arranged between the base plate  11  and the cover plate  12  are a right-hand gear  14  and a left-hand gear  15 , each having grooves  23  into which the bristles  10  slide to be conveyed in the direction of arrow A. The two gears  14 ,  15  are driven by two synchronized drive shafts and are not in meshing engagement with each other, but rather, a gap  19  is provided between the right-hand gear  14  and the left-hand gear  15  through which precut lengths of upstanding bristles (not shown), also designated as filament clusters or strands, which are arranged loosely in a supply duct, are routed directly to a picker segment for picking up the tufts. The gears  14 ,  15  form the lateral boundaries for the gap  19  and serve as pressure surfaces  13 , producing also in this area, similar to what has been described in the foregoing with reference to FIG. 1, a bristle track (not shown)which tapers in the direction of the gap  19 .  
         [0037]    Rotation of the gears  14 ,  15  produces on the pressure surfaces  13 ,  13  tangential forces which bear against the bristles, causing them to move in the direction of arrow A. Hence an active feed unit is obtained, preventing dead zones from developing in the bristle flow. In this embodiment the left-hand gear  15  rotates counterclockwise and the right-hand gear  14  clockwise, yet at equal speed and indexing time.