Patent Publication Number: US-7913519-B2

Title: Latch needle with rotating swivel pin

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the priority of European Patent Application No. 09 153 821.5, filed Feb. 26, 2009, the subject matter of which, in its entirety, is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a latch needle that may be used in textile machines. Such textile machines are, for example, circular knitting machines, flat-bed knitting machines or hosiery machines. 
     A latch needle, as has basically been known from publication DE 36 00 621 C1, has a base body with an end-side hook. The base body is provided with a latch slot in the vicinity of the hook. One end of a latch that is disposed for opening and closing the hook projects into the latch slot. A latch hole is provided on one end of the latch, where a swivel pin extends through said latch hole. The latch slot is delimited by two slot walls. A wall hole is provided in each slot wall. Both wall holes are in alignment with each other. The swivel pin extends through the latch hole and is held by its ends in the wall holes. The outside edges of the two wall holes are deformed radially inward so that the swivel pin is held firmly in place in its axial direction. 
     Considering this solution, the latch hole of the latch is pivotally supported on the stationary swivel pin. Here, any potential wear of the bearing is concentrated on relatively small surfaces. 
     Similar solutions have been known from German Patent 14407 and publication DE 36 0692 A1. 
     German Patent 917243 and German Auslegeschrift 1906892 disclose latch needles with a co-rotating swivel pin. In so doing, DE 917243,  FIG. 2 , provides a latch hole that has a smaller diameter than the wall holes. The swivel pin consists of plastic material and has a diameter greater than the latch hole, however, a diameter smaller than the wall holes. If said swivel pin is drawn into the latch hole with appropriate force, said pin will be seated in said hole in a force-fit manner. The ends of the swivel pin that project from the latch are rotatably supported in the wall holes. 
     As opposed to this, DE 1906892 is based on a swivel pin of steel. Again, the latch hole has a smaller diameter than the wall holes. The swivel pin that is inserted in the latch hole is axially upset, so that it is seated in the latch hole in a force-fit manner. The ends projecting from the latch hole form rivet heads having the form of a truncated cone, said rivet heads being rotatably supported in the wall holes. 
     Whereas the aforementioned publications basically assume the use of swivel pins having essentially two equally configured ends, DE 35 45 037 C2 provides a swivel pin that is arranged asymmetrically with respect to the latch. In this case, only one slot wall is provided with a wall hole that receives the swivel pin. The oppositely arranged slot wall does not have a wall hole. The front side of the swivel pin abuts against this slot wall. Again, the latch is rotatably supported by the round swivel pin. 
     To the extent that the aforementioned solutions relate to swivel pins that co-rotate with the latch, said solutions are based on a force fit between the latch and the swivel pin. Considering mass production, the precise manufacture of such bearing arrangements may result in quality problems. 
     Considering this, it is the object of the invention to provide a latch needle with a bearing arrangement that combines great precision with good wear resistance. 
     SUMMARY OF THE INVENTION 
     The above object generally is achieved with a latch needle that in accordance with the invention comprises a swivel pin that is non-rotationally connected with the latch. The non-rotational securing of the swivel pin on the shaft of the latch occurs by positive connection. This is achieved by a non-round cross-section of the latch hole in the latch shaft. Preferably, the swivel pin also has a matching non-round cross-section. Alternatively, said latter cross-section may adapt to the non-round cross-section of the latch hole if an appropriate deformability of the material is given. Also, a swivel pin that is non-round at least in sections can be used, said swivel pin reshaping an originally differently formed latch hole so as to be non-round. This force fit that is achieved in this or also another manner may be disposed to axially secure the swivel pin in the latch hole, whereby the simultaneously occurring positive connection effects the non-rotational connection between the swivel pin and the latch. 
     The positive connection between the swivel pin and the latch hole effectively and durably prevents a twisting of the swivel pin relative to the latch. In so doing, it can be ensured that the swivel pin with its two ends projecting from the latch hole acts as a bearing, whereby the corresponding counter bearing surfaces are formed by the walls of the two wall holes. Friction and wear are distributed over a relatively large surface, thus resulting in lasting durability. Therefore, the two bearings supporting the swivel pin are formed in the walls that delimit the latch slot. The existing bearing clearance reduces the tilting tendency of the latch, so that, in addition to the latch being guided through the slot walls, another means is provided for guiding the latch in an improved precise manner. 
     The non-round cross-section of the latch hole and the positive connection between the latch shaft of the latch and the swivel pin ensure that the swivel pin will always co-rotate with the latch. Even when the wall holes are loaded with debris, for example abraded materials, dust and the like, and the swivel pin is slowed as a result of this, the latch is still prevented from starting to rotate on the swivel pin. 
     Preferably, the swivel pin has at least a first section, said section having a cross-section that matches the cross-section of the latch hole. This first section ensures the positive connection between the latch hole and the non-round cross-section of the swivel pin. This first section may be configured, for example, as a cylinder whose lateral cylinder surface has at least a notch, a flattened area or the like. Adjoining this first section, there is—optionally but preferably—a second section that has an abutment surface facing the latch. When the swivel pin is inserted into the latch hole, said abutment surface ensures that the swivel pin is guided into the desired central position, in which both ends of the swivel pin project at approximately the same distance from the latch hole. 
     It is possible to provide only the first section of the swivel pin with a non-round cross-section and to configure the second section of the swivel pin in a cylindrical manner. Alternatively, it is also possible to provide both sections with a non-round cross-section. The first and the second sections may optionally be twisted relative to each other in order to provide an abutment surface on the swivel pin for centering said swivel pin as explained above. Two non-round cross-sections may be of significance when the non-round swivel pin cross-section is to be used to free the wall hole from debris/contaminants during the rotation of the latch. 
     Optionally, the swivel pin may be seated with minimal play as well as be tightly fitted, or be oversized, in the latch hole. If a fit with play exists between the swivel pin and the latch hole, it is only the walls delimiting the latch slot that provide a lateral guide for the latch. It may also be advantageous for the pairing of the swivel pin and the latch hole to be configured in such a manner that, as a result of this, an improved guidance of the latch is ensured. In this case, it is advantageous if the swivel pin is seated in a tightly fitted or force-fit manner in the latch hole. As a result of this, a lateral tilting tendency is largely or even completely prevented. The swivel pin is held firmly by the force fit and need not be secured separately in axial direction. 
     If the swivel pin is not seated in the latch hole in a force-fit manner or fastened to the latch in any other way, it may be advantageous to provide an anti-loosening safety on one of the slot walls. This safety feature prevents the swivel pin from being able to fall out of the needle body. This anti-loosening safety is configured as a means that reduces the diameter of the latch hole. As a rule, the anti-loosening safety is applied after the swivel pin has been mounted and can thus be provided by the application of material (welding, gluing, etc.). Such an anti-loosening safety may be provided, for example, in that the outer edge of the wall hole is deformed in a somewhat radially inward manner, so that said edge extends around the end face of the swivel pin. Alternatively or additionally, it is possible to slightly upset the swivel pin on the outer end of the first section, so that said pin is held in the latch hole in a manner that said pin cannot be lost. 
     Additional details of advantageous embodiments of the invention are obvious from the drawings, the description or the claims. The description is restricted to essential aspects of the invention and other situations. The drawings are to be referred to as being supplementary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic side view of a latch needle. 
         FIG. 2  is a partial and perspective representation of the latch needle in accordance with  FIG. 1 . 
         FIG. 3  is a perspective representation of the swivel pin of the latch needle in accordance with  FIG. 2 . 
         FIG. 4  is a perspective representation of the associate latch of the latch needle in accordance with  FIG. 2 . 
         FIGS. 5 and 6  are perspective representations of alternative embodiments of the swivel pin for the latch in accordance with  FIG. 4 . 
         FIGS. 7 and 8  are perspective representations of the latch in accordance with  FIG. 4 , with the swivel pin inserted. 
         FIG. 9  is a perspective representation of a longitudinal section through a slot wall to illustrate the axial securing of the swivel pin. 
         FIGS. 10 through 12  are front views of alternative cross-sections of the swivel pin. 
         FIG. 13  is an illustration of a detail of a longitudinal section through an alternative embodiment of the latch needle in accordance with the invention. 
         FIG. 14  shows another alternative embodiment of the swivel pin. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a schematic representation of a latch needle  1  as is used, for example, in knitting machines or also, in modified form, in hosiery machines. The latch needle  1  has an elongated needle body  2  that is provided with a hook  3  on one end. The other end of the needle body is disposed to act as a guide and/or bearing for the latch needle in a needle bed or a sinker. A driving foot  4  may be provided for knitting machines that require a relative movement between the needle bed and the latch needle  1 . 
     In the vicinity of the hook  3 , there is a latch slot  5  that extends from the needle breast  6  to the needle back  7 , preferably in a continuous manner. The latch slot  5  shown, a detail of which is shown in  FIG. 2 , is delimited by two walls  8 ,  9 , also slot walls, that are preferably arranged parallel to each other and have essentially the same configuration on their opposing internal sides. A latch  10  that is disposed for opening and closing the hook extends with one end  11  into the latch slot  5 , said end delimiting the latch shaft  41  ( FIG. 4 ). The latch shaft  41  is preferably delimited by two flat sides  12 ,  13 . 
     The elongated latch  10  has an end  14  that is, for example, configured as a spoon, said end  14  being remote from the end  11  and, as is shown by  FIG. 2 , being able to abut against the tip of the hook  3  in closed position of the latch  10 . A recess  15  (that is also referred to as a “saw cut”) that is provided on the widened end  14  and faces the hook  3  can accommodate the tip of the hook  3 . However, it is pointed out that, alternatively, it is also possible to provide the hook  3  on its upper side with a longitudinally aligned notch (also referred to as a “saw cut”), into which fits a narrow strip provided on the latch  10 . The latter type of needle is also referred to as a “male latch-female hook type needle”. 
     The latch  10  is pivotally supported in the latch slot  5  by means of a bearing arrangement  16 . To do so, the latch  10  has a latch hole  17  that leads from one lateral surface  12  to the other lateral surface  13 . The latch hole  17  is non-round. For example, as shown in  FIG. 4 , said latch hole has a cross-section that is flattened on one side. Its edge is created by a part  18  that has the form of a circular arc and a part  19  that is straight. 
     In addition, the bearing arrangement  16  comprises a swivel pin  20 , as is obvious from  FIG. 3 , for example. The swivel pin  20  is based on a cylindrical basic shape that extends between its two end faces  21  and  31 . Starting at one of the end faces  21  of the swivel pin  20 , said swivel pin has a first section  22  that deviates from the cylindrical form. At another location of its circumference, the circumference is provided with a flattened area that has an axially aligned, e.g., plane, surface  23 . The surface  23  that is to be measured (in circumferential direction) transversely with respect to the central axis of the basic cylindrical form of the swivel pin  20  corresponds to the length of the straight part  19  of the edge of the latch hole  17 . Viewed in axial direction of the swivel pin  20 , the surface  23  has a length that is preferably smaller than the total length of the swivel pin  20 . The remaining circumference of the first section  22  follows the part  18  of the latch hole, said part having the form of a circular arc, so that the first section  22  fits into the latch hole  17  with minimal or no play. 
     Adjoining the surface  23  there is—optionally but preferably—an abutment surface  24  that separates the first section  22  from the second section  25  of the swivel pin  20 . The first section  22  is preferably longer by the thickness of the latch  10  than the second section  25 , i.e., with respect to the longitudinal direction of the swivel pin  20 . The thickness of the latch  10  is defined as the distance between the lateral surfaces  12 ,  13 . The abutment surface  24  is transverse to the surface  23  and is essentially parallel to the lateral surface  12  or  13 . As is shown by  FIGS. 7 and 8 , the swivel pin  20  fits into the latch hole  17  of the latch  10 . The first section  22  may be inserted through the latch hole  17  until the abutment surface  24  of the second section  25  abuts against the lateral surface  13 . Consequently, the end faces  21 ,  31  of the swivel pin  20  project beyond the lateral surfaces  12 ,  13 . The two parts of the swivel pin  20  projecting from the latch hole  19  have preferably the same length. In addition, they preferably have the same diameter. Whereas the part of the swivel pin  20  projecting beyond the lateral surface  13 , i.e., section  25 , forms a cylindrical journal, the part of the swivel pin  20  that projects beyond the lateral surface  19  also essentially forms a cylindrical journal that is, however, in fact slightly flattened in one area. 
     Wall holes  26 ,  27 —only one of them being shown in  FIGS. 1 and 2 , however both being represented in the other embodiment in accordance with FIG.  13 —in the slot walls  8 ,  9  act to accommodate the parts of the swivel pin  20  projecting from the latch  10 . For example, it is possible to push the swivel pin  20  from one side through the wall hole  26  into the needle body  2  through the latch hole  17  and into the other wall hole  27 . An anti-loosening safety may be provided to prevent the swivel pin  20  from again falling out of the wall hole  26 . This anti-loosening safety consists, for example, of reshaped regions  29 ,  30  of the edge of the wall hole  26 . These regions may be achieved by plastic deformation and extend around the end face  31  of the section  25  of the swivel pin  20 . The relationships are schematically shown in  FIG. 9 . The reshaped regions  29 ,  30  do not impair the rotatability of the swivel pin  20 . 
     The latch needle  1  described so far can be used as any other conventional latch needle  1 . During operation, the latch  10  performs a pivoting movement out of the closed position shown in  FIG. 2  into a rear position, for example, in accordance with  FIG. 1 . During the pivoting movement of the latch  10 , the swivel pin  20  co-rotates with the latch  10 . Due to its cross-sectional form that is different from the circular form in section  22  and corresponds to the cross-sectional form of the latch hole  17 , the swivel pin  20  is in positive connection with the latch  10 . The regions of the swivel pin  20  as are obvious from  FIG. 8 , said regions projecting beyond the lateral surfaces  12 ,  13  on both sides, act as latch-side bearing surfaces. The internal walls of the wall holes  26 ,  27  act as counter bearing surfaces. The thusly formed bearing arrangement  16  displays high wear-resistance, can be reliably manufactured with great precision, and offers a good lateral guide for the latch  10 , so that the latch  10  reliably meets the hook  3 , even in situations of advanced wear. 
       FIG. 5  shows a swivel pin  20 a that may be used as an alternative to the swivel pin  20  in accordance with  FIG. 3  on the latch  10  in accordance with  FIG. 4 . The latter swivel pin is different from the swivel pin  20  in that it has—parallel to the flattened area represented by the surface  23 —another such flattened area  23 ′ on the opposite side of section  22 . This swivel pin  20 a fits into the latch hole  17  in accordance with  FIG. 4 . It is also possible to provide a modified latch hole that has another matching straight part located opposite the straight part  19 . 
     Whereas the swivel pins  20  and  20 a have different cross-sections in their sections  22  and  25 , it is also possible to provide both sections  22  and  25  with the same cross-section.  FIG. 6  illustrates such an exemplary embodiment with the use of the swivel pin  20   b . Section  25 , like section  22 , is flattened. To accomplish this, it has on its circumference a plane surface  32  with a surface normal that—like the surface normal of surface  23 —extends in radial direction. However, the two radial directions of the two surface normals deviate from each other, so that section  25 , again, has an abutment surface  24  as its termination, said abutment surface  24  bordering the surface  23 . 
       FIGS. 10 through 12  illustrate additional embodiments of the swivel pins  20   c ,  20   d , and  20   e . Referring to the swivel pin  20   c  in accordance with  FIG. 10 , the first section  22  has two adjacent facets or surfaces  23 ,  23 ′, which, with a correspondingly formed latch hole, achieve a positive-locking non-rotational coupling between the swivel pin  20   c  and the latches. The second section  25 , as indicated, may be cylindrical or also have another form, for example, may have flattened areas at other circumferential locations. 
     The swivel pin  20   d  shown in  FIG. 11  represents another embodiment. Here, the first section  22  is configured as a polygon, in particular as a four-sided polygon with rounded corners. The second section  25  is cylindrical; however, it may deviate from the cylindrical form. 
       FIG. 12  shows a journal  20   e  having a first section  22  with a peripheral notch  33 , said notch forming a positive connection with a corresponding projection on the latch hole  17 . 
     Considering the above-described embodiments, it was assumed that the swivel pin  20  ( 20   a  through  20   e ) was inserted into the latch hole  17  with only minimal force. Consequently, a separate non-loosening safety is required such as, for example, the non-loosening safety  28 , said safety then being provided on the needle body  2 . 
       FIG. 13  illustrates a modified embodiment that can be used for all of the above-explained swivel pin cross-sections. This embodiment is particularly suitable for symmetrical swivel pin cross-sections in accordance with  FIG. 5  or  FIG. 11 , for example. For this, as is shown by  FIG. 13 , the swivel pin  20  is slightly upset on its section  22  that extends into the wall hole  27 . Consequently, due to its form matching the latch hole, the swivel pin  20  is non-rotationally coupled with the latch shaft  41  of the latch  10 . Relative to its axial direction (that is the transverse direction with respect to the latch  10 ), the swivel pin is held in a non-loosening manner on the rivet head  34  on section  22 , said rivet head having been obtained by the upsetting process. 
       FIG. 14  shows another embodiment of the swivel pin  20   f . The principle as explained with reference to this swivel pin  20   f  can be applied to all forms of swivel pins. This principle consists in that the swivel pin  20   f  is supported in the latch hole  17  by being force-bit. In order to make this possible, the swivel pin  20   f  has the shape of a wedge. The surface  23  is divided into two surface sections  23   a ,  23   b  that, together, subtend an obtuse angle. The surface section  23   a  adjoining the end face  21  is inclined at an acute angle relative to the longitudinal central axis  35 . The longitudinal central axis  35  represents the axis of symmetry of the cylindrical section  25 . The surface section  23   b  adjoins an edge  36  on the surface section  23   a , said edge extending in circumferential direction of the swivel pin  20 . At its other end, the surface section  23   b  adjoins the optional abutment surface  24 . The surface section  23   b  is preferably aligned parallel to the longitudinal central axis  35 . The distance between the edge  36  and the abutment surface  24  is preferably slightly greater than the thickness of the latch  10 . The surface section  23   b  is preferably positioned in such a manner that a force fit is established between the latch  10  and the swivel pin  20   f . The inclination of the surface section  23   a  is preferably such that the end of the swivel pin  20   f  located on the end face  21  fits into the latch hole  17  with play. When the swivel pin  20   f  is inserted, the desired force fit is established between the swivel pin  20   f  and the latch  10 . The force-fit secures the swivel pin  20   f  in axial direction, while the positive connection guarantees the non-rotational coupling. 
     The knitting needle  1  comprises a novel bearing arrangement  16  for its latch  10 . The bearing arrangement  16  comprises a swivel pin  20  that is positively and non-rotationally coupled with the latch. An anti-loosening safety may be provided on the base body  2  of the latch needle  1  in order to axially secure the swivel pin  20  in the latch hole  17 . Alternatively, the swivel pin  20  may be connected with the latch  10  in order to axially secure said swivel pin. 
     It will be appreciated that the above description of the present invention is susceptible to various modifications, changes and modifications, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims. 
     LIST OF REFERENCE NUMERALS 
     
         
           1  Latch needle 
           2  Needle body 
           3  Hook 
           4  Driving foot 
           5  Latch slot 
           6  Needle breast 
           7  Needle back 
           8 ,  9  Walls, slot walls 
           10  Latch 
           11  End 
           12 ,  13  Lateral surfaces 
           14  End 
           15  Recess 
           16  Bearing arrangement 
           17  Latch hole 
           18  Part having the form of a circular arc 
           19  Straight part 
           20  Swivel pin  20   a , . . . ,  20   f    
           21 ,  21 ′ End face 
           22  First section 
           23 ,  23 ′ Surface, flattened area 
           23   a ,  23   b  Surface sections 
           24  Abutment surface 
           25  Section 
           26 ,  27  Wall hole 
           28  Anti-loosening safety 
           29 ,  30  Regions 
           31  End face 
           32  Surface 
           33  Notch 
           34  Rivet head 
           35  Longitudinal central axis 
           36  Edge 
           41  Latch shaft