Abstract:
A novel tufting needle ( 4 ) is distinguished by a hollow flute ( 15 ) which is preferably symmetrical to a central plane ( 29 ) and which is bilaterally provided with chamfers ( 33, 34 ). The chamfers ( 33, 34 ) are, in an inward-located, that is, in a region lying close to the central plane ( 29 ), inclined at a small acute angle (α) to a reference plane ( 28 ), while in a region bordering an externally located rim (edges ( 46, 47 )), the chamfers ( 33, 34 ) are inclined at a larger acute angle (β) to the reference plane ( 28 ). This feature improves the rigidity, the tufting properties and the mechanical strength, as well as the wear resistance of the novel tufting needle ( 4 ).

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/EP2005/001585, filed Feb. 17, 2005, and claims priority of German Patent Application Number 20 2004 004 401.3, filed Mar. 20, 2004, which is incorporated herein, in its entirety, by reference. 
   BACKGROUND OF THE INVENTION 
   The invention relates to an improved tufting needle. 
   Tufting needles are known, for example, from European Patent No. EP 0 874 932 B1. The tufting needle described therein has a basic body whose holding end is held in a holding body, and its other end terminates in a tip adjoined by an eyelet. Further, a yarn groove extends to the eyelet along the shank. 
   U.S. Pat. No. 5,189,966 discloses a tufting needle which has, for a looper, arcuate chamfers at its flanks. However, it does not have a true hollow flute. In the region of the chamfers the shaft has a cross section shaped like an arcuate triangle. 
   Further, International Patent Application No. WO 90/06391 discloses a tufting needle which is provided with a hollow flute in the vicinity of the eyelet. The hollow flute serves for providing a better access to the yarn for a looper or other tools. The tufting needle is flattened and mechanically weakened in the region of the hollow flute. 
   Loopers may abut the tufting needle in the region of the hollow flute and reach into the hollow flute transversely to the needle. During such an operation in time wear appears on the tufting needle because of material abrasion. The tufting needle has to be replaced in case such wear becomes excessive or even results in a break-through to the yarn groove. These occurrences limit the service life of the tufting needle. 
   In the course of the above-noted operation it may occur that, because of uncertainties in the process, the loopers abut the flanks of the tufting needles and thus miss the hollow flute. 
   It is the object of the invention to increase the service life of a tufting needle and, at the same time, to enlarge the inlet space leading to the hollow flute. 
   SUMMARY OF THE INVENTION 
   This object is achieved by the tufting needle as defined in claim  1 : 
   The tufting needle according to the invention has a hollow flute provided with at least one chamfer which has a steeper inclination at its edge adjoining the needle flank than further inward. According to the wording of claim  1  this means that the chamfer in the vicinity of the needle center forms with the reference plane an acute angle α which is smaller than a further outward-lying acute angle β. In this manner the slide angle between a looper and the chamfer of the hollow flute is rendered less pronounced. The looper abuts the chamfer at an outer region which is at the angle β. The latter is, for example, in the range of from 35° to 50°, and is preferably 45°. In this manner a high degree of reliability is ensured during the reception of the yarn loop, because the inlet space for the looper is increased in the region of the hollow flute. An abutting of the looper on the flanks of the needle is virtually avoided. The angle of the chamfer drops inward to a smaller magnitude between 20° and 40°, preferably to 30°. In this manner the friction between the looper and the hollow flute is reduced which results in a diminished wear of the looper and the tufting needle. 
   By means of the radially viewed convex configuration of the chamfer of the hollow flute the thickness of the wall between the chamfer and the yarn groove is increased as compared to planar chamfers. In this manner the service life of the tufting needle is increased up to a possible breakthrough by the looper. Both factors, that is, the reduced friction between the needle and the looper as well as the thicker wall between the yarn groove and the chamfer significantly result, taken individually and in combination, in an increase of the service life of the needle. 
   The needle body may be arranged in the tufting module at a setting angle. This means that the reference plane of the tufting needle is not perpendicular to a setting surface of a needle board. Such a setting which normally increases the friction between the looper and the needle, is well tolerated by the needle according to the invention. 
   The needle body is preferably flattened; this applies particularly to the region of the hollow flute. The portion adjoining the hollow flute too, may have a flattened structure. This feature results in a good elasticity of the needle in a lateral direction thereof and in a high degree of needle rigidity in a lateral direction perpendicular thereto. The latter direction, as a rule, coincides with the transporting direction of the base material. 
   The tufting needle may have a yarn groove. It may be omitted, however, if not required. 
   The hollow flute is preferably of symmetrical structure with respect to a central plane, whereby the needle may be used in an either right-hand or left-hand orientation. 
   In particular, the hollow flute my be provided bilaterally with chamfers to make possible the last-discussed feature. In such an instance, the hollow flute is preferably again symmetrical to the central plane. The mode of operation in a right-hand orientation or a left-hand orientation is then identical. The cross section of the needle in such a case has an upward rounded or faceted, roof-like shape in the region of the hollow flute. Despite the bilateral chamfering of the hollow flute, a large wall thickness toward the yarn groove is obtained. 
   It is also feasible to facet the chamfers, in which case the individual facets may join one another by means of spacious roundings. It is also possible to structure the hollow flute rounded overall, in which case it forms a longitudinally stretched saddle surface. The noted flattened portions and facets on the tufting needle may be obtained by embossing. The thus-produced flattened regions may project laterally beyond the non-embossed shank. A projection of the outer edges of the yarn groove in the region of the hollow flute may amount to approximately between 5% and 20% of the shank width. This enhances, for example, the stability of the tufting needle. 
   Further, the symmetrical arrangement of the chamfers may result in an improved wear behavior of the needles for an additional reason. In case of a unilateral yarn layout, the looper is prevented to a great extent from scraping on the edge of the hollow flute during the return stroke of the needle. The danger that sharp edges will be formed which may damage the carrier material is reduced. 
   Further details of advantageous features of the invention are contained in the drawing, the description or the claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawing, which illustrates an embodiment of the tufting needle according to the invention, 
       FIG. 1  is a fragmentary perspective view of a needle board and a tufting needle module supported thereby, having several, mutually parallel-oriented tufting needles, 
       FIG. 2  is a front elevational view of the module according to  FIG. 1 , 
       FIG. 3  is a side elevational view of the module according to  FIG. 1 , 
       FIG. 4  is a cross section of a tufting needle taken through the region of its hollow flute, 
       FIG. 5  is a front elevational view of one of the tufting needles of the modules according to  FIGS. 2 and 3  and 
       FIG. 6  is a longitudinal sectional view of the tufting needle according to  FIG. 5 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  schematically shows a needle bar  1  supporting a tufting module  2 . The tufting module  2  comprises a body  3  in or on which a group of tufting needles  4  are held. The body  3  lies with a flat side on the front side  5  of the needle board  1 . The tufting needles  4  are spaced parallel to one another and are downward oriented. 
     FIGS. 2 and 3  separately show the tufting module  2 . As seen in  FIG. 2 , the tufting needles  4  are of identical structure and are flattened. They are held in the body  3  at their upper end. Their eyelets  6 , as seen in  FIG. 3 , are, for example, in alignment with one another. 
     FIGS. 4 ,  5  and  6  illustrate the structure of one individual tufting needle  4 . As seen in  FIG. 6 , the tufting needle  4  has a needle body  7  which constitutes a shank  9  extending to a tip  8  which marks the center of the shank  9 . A longitudinal axis  11  defining the length direction of the needle body  7  and the shank  9  passes through the tip  8 . 
   Starting from a first portion  12  which may also be regarded as the clamped portion and which has a substantially circular or at least a rounded cross section, a flattened portion  13  extends toward the tip  8 . The flattened portion  13  is adjoined by a portion  14  which is provided with a hollow flute  15 . The portion  13  is closed upward by a planar surface  16 . The hollow flute  15 , which is closer to the longitudinal axis  11  than the planar surface  16 , forms a longitudinally stretched, saddle-shaped depression. The eyelet  6  is provided in the immediate vicinity of the hollow flute  15 . The eyelet  6  is surrounded by a planar annular surface  17  which is preferably coplanar with the planar surface  16 . From the annular surface  17  a portion  18  extends, in which the needle body  7  tapers toward the tip  8 . 
   As particularly well seen in  FIG. 6 , in the side of the tufting needle  4  lying opposite the planar surface  16 , a yarn groove  19  is formed which extends over the portions  13 ,  14  into the eyelet  6 . The cross section of the yarn groove  19  is essentially constant along its entire length.  FIG. 4  shows the cross section of the tufting needle  4 , taken along the line IV-IV of  FIG. 5 .  FIGS. 4 and 5  show structures on different scales. As illustrated in  FIG. 4 , the yarn groove  19  has preferably an approximately trapezoidal shape. The yarn groove  19  is bilaterally adjoined by legs  21 ,  22  which are bordered by planar surfaces  23 ,  24  at the side of the yarn groove. The planar surfaces  23 ,  24  form an obtuse angle with one another; they terminate in edges  25 ,  26  which lie radially significantly externally of an outline  27  which contains the portion  12  of the shank  9 . The legs  21 ,  22  thus project beyond the outline  27 . 
   In the illustration according to  FIG. 4 , the eyelet which is cut away and is thus not visible, has a vertical opening direction oriented perpendicularly to a reference plane  28 . The latter, in turn, is parallel to the planar surface  16  and extends longitudinally through the tufting needle  4  and thus contains the longitudinal axis  11 . Perpendicularly to the reference plane  28  a central plane  29  is to be imagined which intersects the reference plane  28  in a line of intersection which is the longitudinal axis  11 . The central plane  29  constitutes a symmetry plane for the tufting needle  4 . 
   The shape of the hollow flute  15  is particularly well seen in  FIG. 4 . Starting from an edge bordering the planar surface  16 , a rounding  31  is provided which changes into linear surfaces relative to the length direction. These surfaces comprise a planar surface  32  which is symmetrical to the central plane  29  and which is oriented preferably parallel to the reference plane  28 . Bilaterally of the planar surface  32  chamfers  33 ,  34  are arranged which intersect the reference plane  28  and which are symmetrical to the central plane  29 . In the present embodiment the chamfers  33 ,  34  are faceted. Accordingly, each chamfer  33 ,  34  has two strip-shaped planar surfaces  35 ,  36  and, respectively,  37 ,  38  which change into a rounded or arcuate surface  41 ,  42 . The surface  41  lies between the planar surfaces  35 ,  36  and the surface  42  lies between the planar surfaces  37 ,  38 . Further, the chamfers  33 ,  34  join the planar surface  32  with the intermediary of rounded or arcuate surfaces  43 ,  44 . The planar surfaces  35 ,  36  as well as  37 ,  38  form in each instance pair-wise an obtuse angle with one another. In this manner, as shown in  FIG. 4 , they are oriented at different angles to the reference plane  28  or to a plane parallel thereto. The planar surface  38  forms an acute angle α with a line  45  which is parallel to the reference plane  28 . The same applies to the planar surface  36 . The planar surface  37  forms an acute angle β with the line  45 . The same applies to the planar surface  35 . The angle α is smaller than the angle β. The angle α lies preferably in the range of 20° to 40°. In the present preferred embodiment α is 30°. The angle β lies preferably in the range of 35° to 55°. In the present preferred embodiment β is 45°. The planar surfaces  35 ,  37  are disposed such that they terminate preferably in an edge  46 ,  47  which lies externally of the outline  27 . In this manner the outer flanks  48 ,  49  of the portion  14  are disposed externally of the outline  27 . The flanks  48 ,  49  are preferably slightly curved. 
   The tufting needle  4  described up to this point operates as follows: 
   In use, a yarn is guided through the yarn groove and the eyelet  6 . As the tufting needle  4  pierces a base material, the yarn is pulled therethrough by the eyelet. In the vicinity of its lower point of reversal, a hook-shaped looper is moved toward the tufting needle  4 . First the looper abuts with its tip the planar surface  37 . Based on the substantial inclination of the surface  37  to the reference plane  28  (the acute angle β), a large distance between the edge  47  and the line  45  is obtained. Independently of any non-alignment, tolerances, inaccuracies or bendings, the tip of the looper thus securely abuts the chamfer  34 . Then it first slides on and along the planar surface  37  and thereafter reaches the planar surface  38 . Friction is reduced by virtue of the small angle (the smaller acute angle α) of the planar surface  38  to the reference plane  28 . Subsequently, the looper is guided over and beyond the planar surface  32 , so that during the return stroke of the needle, the looper may firmly hold the yarn which pierced the base material by the eyelet. 
   The arching present in the chamfers  33 ,  34  results, at  41  and, respectively, at  42 , in an enlargement of the wall thickness a, b toward the yarn groove  19 . This eventually enhances not only the rigidity of the tufting needle  4 , but its wear resistance as well. A gradual abrasion of such a wall leads to an impermissible wear only after a very long use. 
   
     
       
             
           
             
             
             
           
         
             
                 
             
             
               List of Reference Characters: 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
                 
                1 
               needle board 
             
             
                 
                2 
               tufting module 
             
             
                 
                3 
               body 
             
             
                 
                4 
               tufting needle 
             
             
                 
                5 
               front side 
             
             
                 
                6 
               eyelet 
             
             
                 
                7 
               needle body 
             
             
                 
                8 
               tip 
             
             
                 
                9 
               shank 
             
             
                 
               11 
               longitudinal axis 
             
             
                 
               12, 13, 14 
               portion 
             
             
                 
               15 
               hollow flute 
             
             
                 
               16 
               planar surface 
             
             
                 
               17 
               annular surface 
             
             
                 
               18 
               portion 
             
             
                 
               19 
               yarn groove 
             
             
                 
               21, 22 
               legs 
             
             
                 
               23, 24 
               planar surfaces 
             
             
                 
               25, 26 
               edges 
             
             
                 
               27 
               outline 
             
             
                 
               28 
               reference plane 
             
             
                 
               29 
               central plane, needle center 
             
             
                 
               31 
               rounding 
             
             
                 
               32 
               planar surface 
             
             
                 
               33, 34 
               chamfers 
             
             
                 
               35, 36; 37, 38 
               planar surfaces 
             
             
                 
               41, 42; 43, 44 
               surface 
             
             
                 
               45 
               line 
             
             
                 
               46, 47 
               edge 
             
             
                 
               48, 49 
               flanks