Patent Document

BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a manufacturing process for a loom heddle. The invention also relates to a heddle for a shed-forming mechanism on a loom, as well as to a loom equipped with such a mechanism. 
   2. Brief Description of Related Art 
   In the domain of forming the shed, equipping a heddle with a warp yarn guiding eyelet is known; the material and the shape of this eyelet are chosen so as not to damage the warp yarn traversing the central orifice defined by this eyelet. From FR-A-2 267 403 bonding an eyelet in a longitudinal slit formed in a threadlike element making up a heddle is known. Some eyelets described are provided with an outer peripheral groove intended to make it easier to keep them in the opening of the threadlike element. These eyelets have a thickness greater than that of the threadlike element, which leads to a risk of the warp yarn catching during weaving. Furthermore, such a peripheral groove is difficult to make, especially in high carbon steels used to manufacture the eyelets. In particular, although such a groove is conceivable with circular eyelets, this is achievable only with very very great difficulty, exclusively by machining, in an oblong eyelet. Additionally the oblong eyelet from this prior art does not have a groove, to the point that keeping it in position relative to the threadlike element is somewhat random. 
   FR-A-2 776 676 calls for the implementation of an oblong-shaped eyelet provided with a groove intended to receive adhesive or welding material. In practice, such a groove is difficult to implement. 
   EP-A-1 015 675 shows the use of an oblong eyelet forming a groove for receiving two strands making up a threadlike element, in order to keep this eyelet in place, the eyelet further being bonded to these strands. The shape imposed on the eyelet to allow its manufacture by forming is such that significant holes remain respectively above and below the eyelet, these holes having to be filled with adhesive. This is difficult to perform and leads to an increased consumption of adhesive which considerably increases the manufacturing cost of the heddle. 
   These disadvantages are what the invention more specifically intends to remedy by proposing a novel manufacturing process for a loom heddle which makes possible a more effective attachment of an eyelet the shape of which can be adapted to that of the opening in which it is placed. 
   SUMMARY OF THE INVENTION 
   The invention relates to a process for manufacturing a loom heddle, this process including steps consisting in: 
   a) manufacturing an eyelet for guiding a warp yarn; 
   b) making an opening for receiving this eyelet in a threadlike element, and c) placing and immobilizing the eyelet in the aforementioned opening. 
   This process is characterized in that: 
   d) during the manufacture of the eyelet or the implementation of the opening, on an edge of a first element among the eyelet and the opening, are formed at least two projecting tabs offset from each other both along this edge and perpendicularly to the principal faces of this first element. 
   e) during the placement of the eyelet in the aforementioned opening, a part of the edge of the second element, among the eyelet and the opening, is engaged with the-projecting tabs. 
   Thanks to the invention, the projecting tabs provide an effective attachment of the eyelet in the opening of the threadlike element. The offset of the two tabs both along the edge of the eyelet or opening and perpendicularly to the principal faces of the eyelet or the threadlike element corresponds to a “staggered” placement of the tabs which allows them to each interact with one side of the threadlike element or eyelet, all while being able to be manufactured more simply without having recourse to complex machining lines, which is even more significant since the eyelets have very small dimensions. The fact of providing an attachment for the eyelet on the threadlike element through two projecting tabs avoids having recourse to a continuous peripheral groove on the edge of the eyelet. This allows a shape which for this edge can be adapted to the geometry of the opening created in the threadlike element. 
   According to advantageous but not mandatory aspects of the invention, such a process can incorporate one or more of the following features taken in any technically allowable combinations:
         A step of thinning and sizing the edge intended to be engaged with or inserted between the projecting tabs is provided, the step being prior to step e). This thinning and sizing step is preferably carried out by localized die-stamping of the threadlike element; this die-stamping creates, on each side of this element, a housing for receiving one of the tabs and this thinning step is followed by a step of forming a longitudinal slit in the threadlike element, this slit then being enlarged to-make the aforementioned opening;   On the edge of the second element, projecting tabs are formed which are complementary to those formed on the edge of the first element; these complementary tabs are offset from each other along the edge of the second element and perpendicularly to the principal faces of the second element, with an inverse distribution from that of the tabs formed on the first element;   The eyelet or the opening is made by cutting, whereas the tabs are made by die-stamping or forging. This proves particularly economical and is compatible with high speed production.       

   The invention also relates to a heddle that can be made through the previously mentioned process and, more specifically, a heddle for a shed-forming mechanism on a loom, with this heddle including a threadlike element and also an eyelet immobilized in an opening arranged in this threadlike element. This heddle is characterized in that a first element, among the eyelet and the opening, has, on one edge, at least two projecting tabs offset from each other along this edge and perpendicularly to the principal faces of this first element, whereas a part of the edge of the second element is engaged with these tabs. 
   Such a heddle is more economical to manufacture than the heddles of the prior art, while it ensures a more effective guiding of the warp yarn without risk of damaging it. 
   According to advantageous but not mandatory aspects of the invention, such a heddle may incorporate one or more of the following features taken in any technically allowable combinations:
         The thickness of the eyelet is roughly equal to the maximum thickness of the threadlike element, including in the area of the tabs.   The edge which is partly engaged between the projecting tabs is, at least in the area of its part inserted between these tabs, thinned relative to the maximum thickness of the threadlike element or the eyelet.   The second element has, on one edge, projecting tabs which are complementary to those formed on the edge of the first element; these complementary tabs are offset from each other along the edge of the second element and are perpendicular to its principal faces, with an inverse distribution from that of the tabs formed on the first element.   Each tab is on one of its sides, flush with a principal face of the eyelet or of the threadlike element which is perpendicular to the aforementioned axis.   The threadlike element is made of stainless steel and the eyelet is bonded in the opening provided in this element.   The eyelet or the opening is provided with eight tabs distributed on its outer edge in groups of two tabs offset relative to each other along this edge and in a direction parallel to a central axis of the guiding hole formed by the eyelet.       

   Finally the invention relates to a loom equipped with a shed-forming mechanism including at least one heddle such as mentioned above. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood and other advantages of it will appear more clearly in light of the following description of four embodiments of a heddle conforming to its principle and its manufacturing process, given solely as examples and with in reference to the attached drawings in which: 
       FIG. 1  is a schematic representation of a loom conforming to the invention; 
       FIG. 2  is a perspective view at a larger scale of the central part of a heddle for the loom from  FIG. 1 ; 
       FIG. 3  is a partial principal section at a larger scale along the line III-III on  FIG. 2 ; 
       FIG. 4  is a front view at a larger scale of the eyelet from the heddle on  FIGS. 2 and 3 ; 
       FIG. 5  is a cross section along the line IV-IV on  FIG. 4 ; 
       FIG. 6  is a side view in the direction of the arrow VI on  FIG. 4 ; 
       FIG. 7  is a partial front view of a threadlike element intended to make up part of the heddle on  FIGS. 2 and 3 , during a first manufacturing step; 
       FIG. 8  is a cross section along the line VIII-VIII on  FIG. 7 ; 
       FIG. 9  is a cross section analogous to  FIG. 8 , during a second manufacturing step; 
       FIG. 10  is a perspective view analogous to  FIG. 2 , during a third manufacturing step; 
       FIG. 11  is a view analogous to  FIG. 2  for a heddle conforming to a second embodiment of the invention; 
       FIG. 12  is a partial representation of the edge of an eyelet and the edge of an opening of a threadlike element of a heddle conforming to a third embodiment of the invention; 
       FIGS. 12A ,  12 B and  12 C are respectively cross sections along the lines A-A, B-B and C-C on  FIG. 12 ; 
       FIG. 13  is a view analogous to  FIG. 12  where the heddle is undergoing manufacture during a step corresponding to  FIG. 10  for the first embodiment; and 
       FIGS. 14A and 14B  are cross sections analogous respectively to  FIGS. 12A and 12B  for a heddle conforming to a fourth embodiment of the invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   The loom M shown in  FIG. 1  is equipped with a Jacquard mechanism  2  which controls several harness strings  4  the lower end of which is associated with several cords  6 . The lower end  6   a  of each cord  6  is connected to the upper end  8   a  of a heddle  8 , each heddle  8  being provided with an eyelet  9  for passage of a warp yarn  10  and subject to the action of a restoring spring  12  fixed to the frame  14  of the loom through a stem  16 . 
   The heddle  8  is formed from a threadlike element  81  which initially has the shape of a stainless steel wire with circular cross section. This thread is crushed to have a flattened transverse section. In its central part, the element  81  is separated into two branches  82  and  83  between which an opening  84  is defined for receiving the eyelet  9 . 
   The eyelet  9  is obtained by cutting of a strip of metal, preferably a strip of carbon steel. It defines an orifice  91  for passage of the warp yarn  10 . The central axis of the orifice  91 , is referenced X 91 . This axis is perpendicular to the principal faces  92  and  93  of the eyelet  9 , that is its faces with the largest areas. 
   The eyelet  9  has an oblong shape and its outer edge, which is overall oval or in the form of a flattened ellipse, is referenced  94 . 
   The edge  94  is equipped with eight tabs  95  of which four, bearing the reference  95   a , have one of their sides flush with the surface  92  whereas the four other tabs, bearing the reference  95   b , have one of their sides flush with the surface  93 . 
   The tabs  95   a  and  95   b  project relative to the edge  94  and are laid out in pairs along the edge  94 , each pair including a tab  95   a  and a tab  95   b , these tabs being laterally offset from each other along the edge  94 . 
   The median plane of the eyelet  9 , i.e a plane parallel to the faces  92  and  93  and equidistant from them, is denoted by P 9 . The tabs  95   a  and  95   b  are distributed on both sides of this plane. In particular, the tabs  95   a  and  95   b  of a single pair of tabs are offset on both sides of this plane along a direction D 9  parallel to the axis X 91 . Looking at the section of the eyelet  9  shown in  FIG. 5 , it could be considered that the tabs  95   a  and  95   b  are placed in staggered rows on both sides of the plane P 9 . The tabs  95   a  and  95   b  from a single pair are offset along the edge  94  by a non-zero distance d, and parallel to the direction D 9 , by a distance d′, taken between the centres of the tabs  95   a  and  95   b , which is also non-zero. 
   The succession of two tabs  95   a  and  95   b  from a single pair forms a volume V, shown in grey in  FIG. 6  with a width d′, in which the edge  85  of the opening  84  can be partially introduced in order to firmly retain the eyelet  9  in position in this opening. 
   In order to be able to be introduced in this grey volume V, the edge  85  is thinned as shown on  FIGS. 7 to 10 . When the element  81  is shaped to make the heddle  8 , it is die-stamped along a length corresponding to the largest dimension of the opening  84  to form, from each of its largest dimensions or principal faces  86  and  87 , two housings  86   a  and  87   a  which each extend on two depths P 1  and P 2  where the larger depth P 2  corresponds to the central zone of each of the housings  86   a  and  87   a.    
   Once the housings  86   a  and  87   a  have been formed by die-stamping of the element  81 , a slit  88  is created in their bottom part, as shown in  FIG. 9 . This slit joins the deepest parts of the housings  86   a  and  87   a . By the formation of this slit  88 , branches  82  and  83  are created which can then be separated from each other, in the direction of the arrows F 2  in  FIGS. 9 and 10 , to reach the position of  FIG. 10  where the branches  82  and  83  define between them the opening  84  with transverse dimensions greater than the dimensions of the eyelet  9  in the plane visible on  FIG. 4 . 
   At the end of this operation, the edge  85  forms, on its entire length, a sized nose  85   a  on both sides of which are arranged two shoulders  85   b  of depth p i . The nose  85   a  has a width l 85  measured parallel to the axis X 91 , less than the thickness e 81  of the element  81  and than the distance d′. 
   As shown in  FIG. 10 , it is then possible to place the eyelet  9  in the opening.  84  after having pulled away the branches  82  and  83  by elastic deformation, and then letting them come back towards each other in the direction of the arrows F 3  in this figure, which comes back to insert locally, meaning to engage, the nose  85   a  of the edge  85  in the volumes V defined by the two tabs  95   a  and  95   b  of each pair of tabs. The eyelet  9  is then held, firmly and without play by the branches  82  and  83 . 
   To ensure the durability of the attachment and fill the holes between the eyelet  9  and the element  81 , adhesive is applied in the holes  84   a  which remain on both sides of the eyelet  9 . By capillarity the adhesive spreads in the area of at least part of the interface between the edge  85  and the eyelet  9 . This adhesive can be of any known type and, in particular, a single-component epoxy adhesive cured by ultraviolet radiation, or an anaerobic adhesive cured by ultraviolet radiation. 
   The thickness of each of the tabs  95  is referenced e 95 . This thickness is slightly less than the depth P 1  of the housings  86   a  and  87   a . Further, the total thickness e 9  of the eyelet  9  is chosen roughly equal to the thickness e 81 . Thus, when the eyelet  9  is pinched and bonded in the opening  84  as shown in  FIG. 3 , its faces  92  and  93  can be flush with the faces  86  and  87  of the element  81 , since the tabs  95  are received in the shoulders  85   b  of both sides of the nose  85   a.    
   The positioning of the tabs  95   a  and  95   b , which are offset from each other along the edge  94 , makes it possible to make these tabs by die-stamping of the steel strip out of which the eyelet  9  is cut. As a variant, the eyelet can be made by cold forging. The fact of using die-stamping or forging for creating the tabs  95  avoids having to use machining operations which would be very costly and delicate to implement considering the size of the eyelet  9  whose length in practice is less than 20 mm, preferably less than 10 mm. 
   In consideration of the manufacture method for the eyelets  9  by cutting, die-stamping and/or forging, it is not necessary to make use of a circular slug of the type of that used in FR-A-2 267 403 or EP-A-1 015 675, which makes it possible to adapt the shape of the edge  94  to the final shape of the opening  84 . So, the holes  84   a  that may need to be filled with adhesive can be of reduced size compared to the total surface of the opening  84 . 
   The manufacture method for the eyelets  9  enables very high production rates because the various operations used can be done on a single machine with several work positions, and the shaping tools all have displacements perpendicular to the plane P 9 . 
   The fact that the eyelet is bonded to the element  81  and not welded onto it allows this element  81  to be made of stainless steel. The use of a stainless steel element  81  makes it possible to dispense with conventional nickel plating operations on non-stainless steel elements, while these nickel plating operations are likely to generate the appearance of burrs or “scratchings” which can damage or cut the warp yarn. 
   In the second embodiment of the invention shown in  FIG. 11 , the elements analogous to those from the first embodiment have identical references. This embodiment shows an inverted or “mirror” solution relative to the first embodiment in the sense that the tabs  95   a  and  95   b  are distributed on the edge  85  of the opening  84  arranged in the threadlike element  81  of the heddle  8 , whereas the outer edge  94  of the eyelet  9  is thinned and has a nose  94   a  thinner than the eyelet and intended to be inserted in the volume defined by the two adjacent tabs  95   a  and  95   b  of a single pair of tabs  95 . As in the first embodiment, the tabs  95   a  and  95   b  are staggered, being offset from each other both parallel to the edge  85 , as shown by the distance d in  FIG. 11 , and perpendicularly to it along the direction of the axis X 91  of the orifice  91  defined by the eyelet  9 . 
   The tabs  95   a  and  95   b  are flush to the lateral faces of the threadlike element  81 . 
   As in the first embodiment, the eyelet  9  can be immobilized by a clamping force F 3  due to the branches  82  and  83  of the element  81  and by being bonded, in order to obtain additional anchoring. 
   As shown in  FIGS. 12 and 13  where the elements analogous to those from the first embodiment have the same references, the edge  94  of the eyelet  9  can be provided with two tabs  95   a  and  95   b  which form a pair of tabs  95  which are offset as in the first embodiment. The tab  95   a  is flush with a principal face  92  of the eyelet  9 , whereas the tab  95   b  is flush with the opposite principal face  93 . 
   Similarly, the edge  85  of the branch  82  of the threadlike element  81  is provided with two projecting tabs  95 ′, specifically one tab  95 ′ a  flush with the principal face  86  of the branch  82  and one tab  95 ′ b  flush with the opposite face  87  of this branch. The tabs  95 ′ are offset from each other along the edge  85  by a distance d identical to the offset distance d of the tabs  95  relative to each other along the edge  94 . The tabs  95 ′ are also offset from each other perpendicularly to the faces  86  and  87  by a distance d′ between their respective centres, just like the tabs  95  are offset perpendicularly to the faces  92  and  93  by the same distance d′. The direction of offset of the tabs  95 ′ perpendicularly to the faces  86  and  87  is the inverse of that of the tabs  95 . 
   It is thereby possible during the placement of the eyelet  9  in the opening  84  to bring the tabs  95   a  and  95 ′ b  into a position overlapping one another whereas the tabs  95 ′ a  and  95   b  are brought into a position overlapping one another, as shown respectively in  FIGS. 12A and 12B . 
   In the portions of the edges  94  and  85  free of tabs, these edges are straight and perpendicular to the principal faces  86  and  87 , and  92  and  93  of the elements  9  and  81 , as shown in  FIG. 12C . 
   As the  FIGS. 14A and 14B  show, the tabs  95   a ,  95   b ,  95 ′ a  and  95 ′ b  can be chamfered, that is having a surface inclined at about 45° to the principal faces  86 ,  87 ,  92  and  93  of the elements  81  and  9 , while being offset perpendicularly to these faces by a distance d′, along the edges  85  and  94 . 
   As a variant, in the four embodiments described, as the blocking of the eyelet  9  in the opening  84 , obtained through the elasticity of the branches  82  and  83 , is very effective, the bonding of the eyelet in this opening can be eliminated. 
   The invention was shown in the first two embodiments with an eyelet and an opening whose edge  94  or  85  is equipped with eight tabs  95 . In practice, the number of tabs  95  results from a design choice by a specialist who may decide to use only two of these tabs or an arbitrary number of them. This number can be less or more than eight. When more than two tabs are used, they are advantageously distributed along the length of the edge  94  or  85 , preferably in pairs. 
   The invention was shown in its implementation for the manufacture of a heddle for a Jacquard type loom. It also applies to the manufacture of a heddle intended to be mounted on a loom frame, this frame being driven by a weave mechanism, for example a dobby or basic weave mechanism.

Technology Category: d