Patent Publication Number: US-2003226609-A1

Title: Apparatus for the manufacture of leno cloths

Description:
[0001] The invention relates to an apparatus for the manufacture of leno cloths in a weaving machine in accordance with the preamble of claim 1 and to a weaving machine comprising an apparatus of this kind.  
       [0002] Leno cloths contain two warp thread systems, a warp thread system consisting of ground threads and a warp thread system consisting of leno threads. The ground and leno threads intertwine with one another, in order in this manner to bind in the weft threads in a displacement resistant manner.  
       [0003] An apparatus for forming a leno binding, comprising a reed as well as a needle bar with ground needles for the guiding of ground threads and a guide rail arrangement with a movably mounted guide rail for the horizontal and vertical displacement of leno threads, is known from the specification EP-A-1 101 850. As can be seen in FIG. 4, the guide rail arrangement is suspended in a heald frame at a kind of heald carrier rail. At larger weaving widths this arrangement is not stable enough to take up the forces which are usually exerted by the leno threads, which leads to twisting effects. The mounting and the driving of the needle bar for the ground threads are not described in further detail in the specification EP-A-1 101 850; however, stability problems also arise here at larger weaving widths. As can be seen in FIG. 2, the forces which are exerted by the ground threads on the needle bar have not only a vertical component, but rather, through the two-fold deflection of the ground threads in the region of the needle bar, a torque also arises which acts on the needle bar for the ground threads and their carrier, and appears in a disturbing manner.  
       [0004] The object of the invention is to make available an apparatus for the manufacture of leno cloths in a weaving machine which avoids the disadvantages from the prior art and which comprises a more stable frame structure with a strengthened drive for the mounting of a needle bar for ground threads and of guide means for leno threads, in particular a frame structure which is suitable for taking up the torque which acts on the needle bar for the ground threads. A further object of the invention is to make available a weaving machine with an apparatus of this kind.  
       [0005] This object is satisfied in accordance with the invention by the apparatus which is defined in claim 1 and by the weaving machine which is defined in claim 10.  
       [0006] The apparatus in accordance with the invention for the manufacture of leno cloths in a weaving machine comprises a needle bar for the guiding of ground threads as well as guide means, for example a guide rail or a second needle bar, for guiding leno threads. The weaving machine comprises a dobby, for example an eccenter dobby, as well as a reed for beating up the inserted weft threads. The guide means for the leno threads are horizontally movably mounted in order to laterally deflect the leno threads; and the needle bar for the ground threads and the guide means for the leno threads are arranged ahead of the reed when viewed in the direction of the warp travel. Furthermore, the needle bar for the ground threads and/or the guide means for the leno threads are vertically movably mounted and are operatively connected with the dobby in order to deflect the ground threads and/or the leno threads respectively in the vertical direction, with at least one of the operative connections between the needle bar and the dobby and/or between the guide means for the leno threads and the dobby respectively comprising a plurality of heald drive bars which start at the dobby.  
       [0007] The heald drive bars preferably comprise vertically acting drive elements which are arranged distributed over the length of the needle bar for the ground threads and/or of the guide means for the leno threads, with the needle bar for the ground threads and/or the guide means for the leno threads respectively being actively connected to the vertically acting drive elements via elastic coupling elements, for example elastic elements such as are known from the patent specification CH 623 364. The needle bar for the ground threads and/or the guide means for the leno threads are preferably each arranged on a frame structure, which is provided with vertical struts which are arranged distributed over the length of the needle bar and/or of the guide means for the leno threads respectively.  
       [0008] In a preferred embodiment the apparatus comprises a frame which is designed in box shape, on which the needle bar for the ground threads is arranged together with a deflection element for the ground threads and which is vertically movably mounted and operatively connected to the dobby via at least two of the heald drive bars ( 13 . 1 ,  13 . 2 ) which depart from the dobby. Typically, one dimension of the box shaped frame extends in the vertical direction, one in the longitudinal direction of the needle bar for the ground threads and one in the longitudinal direction of the ground and leno threads. The at least two heald drive bars are preferably arranged with spacing in the longitudinal direction of the ground and leno threads. The box shaped frame is preferably stiffened in the transverse direction through bridge-like elements and/or struts, which are distributed over the length of the frame.  
       [0009] In a further advantageous embodiment the apparatus comprises a plurality of rotatably journalled support levers, which are arranged distributed over the length of the needle bar for the ground threads and to which the needle bar for the ground threads is connected, the support levers having a common axis of rotation which is arranged so as to be displaced from the needle bar in the longitudinal direction of the ground and leno threads.  
       [0010] In a further advantageous embodiment the apparatus comprises a plurality of four-bar linkages which are arranged distributed over the length of the needle bar for the ground threads, with in each case two substantially vertically extending sides, of which one side is fixedly arranged in the weaving machine and one is movable, with the movable side being connected at the one end to the needle bar for the ground threads and at the other end to the vertically acting drive elements.  
       [0011] The guide means for the leno threads are preferably actively connected to the dobby via a further heald drive bar in order to be able to deflect the guide means for the leno threads in the horizontal direction.  
       [0012] Furthermore, the invention comprises a weaving machine with an apparatus in accordance with the invention for the manufacture of leno cloths.  
       [0013] The apparatus in accordance with the invention for the manufacture of leno cloths in a weaving machine has the advantage that the drive for the vertical movement of the needle bar for the ground threads and/or the vertical movement of the guide means for the leno threads is in each case distributed over at least two heald drive bars which depart from the dobby. The twisting of the heald drive bars and the wear are thereby significantly reduced. This advantage is particularly important at large weaving widths.  
       [0014] Through the elastic coupling elements which are described in one embodiment, and via which the needle bar for the ground threads and/or the guide means for the leno threads are actively connected to the vertically acting drive elements, deviations such as for example manufacturing differences (tolerances) between the heald drive bars are taken up and the wear is additionally reduced. In a further, above described embodiment the needle bar for the ground threads and/or the guide means for the leno threads are each arranged on a frame structure which is provided with vertical struts which are arranged distributed over the length of the needle bar and/or the guide means for the leno threads. This frame structure combines in an advantageous manner low mass with high stiffness in the vertical direction, which makes it particularly suitable for taking up the vertical forces which are exerted by the ground or the leno threads respectively.  
       [0015] In a preferred embodiment, which was described above, the apparatus comprises a frame which is designed in box shape and on which the needle bar for the ground threads is arranged together with a deflection element for the ground threads. The box shaped frame, which could also be protected as an independent invention, is eminently suitable for taking up the torque which acts on the needle bar and the deflection element without a disturbing twisting.  
       [0016] The connection of the needle bar for the ground threads with support levers or four-bar linkages respectively, which is described in two further advantageous embodiments, likewise has the advantage that the torque which acts on the needle bar for the ground threads and the deflection element can be taken up without a disturbing twisting. 
     
    
    
     [0017] Further advantageous embodiments result from the subordinate claims and the drawings.  
     [0018] In the following the invention will be explained in more detail with reference to exemplary embodiments and with reference to the drawings. Shown are:  
     [0019]FIG. 1 a  a schematic perspective view of a first exemplary embodiment pertaining to the present invention,  
     [0020]FIG. 1 b  a continuation of the schematic perspective view of FIG. 1 a  with a heald drive bar for the horizontal movement of a guide rail,  
     [0021]FIG. 2 the first exemplary embodiment in cross-section,  
     [0022]FIG. 2 a  a detail view of an alternative embodiment with an eyed reed instead of a needle bar,  
     [0023]FIG. 3 an embodiment with a support lever in cross-section,  
     [0024]FIG. 4 an embodiment with a four-bar linkage in cross-section,  
     [0025]FIG. 5 a  an embodiment with a stationarily mounted needle bar for the ground threads in cross-section,  
     [0026]FIG. 5 b  a variant of a frame structure for the mounting of a guide rail in cross-section, and  
     [0027]FIG. 5 c  a detail from a horizontal section through a guide rail arrangement, such as is illustrated in FIGS. 1 a  through  5   a.   
    
    
     [0028] In some publications on the manufacture of leno cloths the designations ‘ground thread’ and ‘leno thread’ are reversed with respect to the following description. However, the choice of the terminology has no influence on the design and functioning of the described apparatus.  
     [0029]FIGS. 1 a,    1   b  and  2  show a perspective view and a cross-section of a first exemplary embodiment of an apparatus for the manufacture of leno cloths in a weaving machine in accordance with the present invention. The apparatus  1  in accordance with the invention comprises a needle bar  7 ,  7 ′ having ground lamella  7   a , which are provided at the free end with eyes and a deflection element  5  for guiding ground threads  4 ,  4 ′ as well as guide means, which are executed in the first exemplary embodiment as a guide rail arrangement  8 ,  8 ′, for the guiding of leno threads  3 ,  3 ′. The weaving machine is equipped with a dobby, for example an eccentric dobby, which is not shown in the figures, as well as with a reed  2 ,  2 ′ for the beating up of inserted weft threads  19 . The guide rail arrangement  8 ,  8 ′ comprises a guide rail  8   a  and horizontal guides in which the guide rail is mounted and guided so as to be horizontally movable. Furthermore, the guide rail  8   a  is connected to the dobby via a heald drive bar with a connecting rod  12  and horizontally acting drive elements  17  in order to be able to deflect the leno threads laterally. As can be seen in FIG. 2, the needle bar  7 ,  7 ′ for the ground threads and the guide rail  8 ,  8 ′ are arranged ahead of the reed  2 ,  2 ′ when viewed in the direction of travel of the warp.  
     [0030] In the present exemplary embodiment both the needle bar  7 ,  7 ′ for the ground threads and the guide rail are mounted so as to be vertically movable and are operatively connected via heald drive bars to the dobby in order to be able to deflect the ground threads and leno threads in the vertical direction, with the operative connection of the needle bar  7 ,  7 ′ for the ground threads to the dobby comprising at least two heald drive bars which depart from the dobby. In the present description it is assumed that one heald drive bar is present per heald drive bar position of the dobby, with a usual dobby being equipped for example with  10  heald drive bar positions. In one variant embodiment the guide rail arrangement  8 ,  8 ′ is also actively connected to the dobby, as indicated in FIG. 2, via two heald drive bars which depart from the dobby. The heald drive bars comprise connecting bars  11 ,  13 . 1 ,  13 . 2  and vertically acting drive elements  10 ,  10 . 1 ,  10 . 2 ,  16  which are arranged distributed over the length of the needle bar, with the needle bar and the guide rail arrangement being actively connected to the vertically acting drive elements via elastic coupling elements. In the exemplary embodiment the elastic coupling elements are executed in a known manner as elastic bearing bushes, via which the vertically acting drive elements are coupled to the longitudinal carriers  14 . 1 ,  14 . 2 ,  18 . Provided for the vertical guidance of the guide rail arrangement are, on the one hand, laterally arranged heald frame guides and, on the other hand, vertical guides  15  with guide lugs  15   a , which are arranged distributed over the length of the guide rail arrangement.  
     [0031] In the exemplary embodiment the guide rail arrangement  8 ,  8 ′ is arranged on a frame structure  9 , which is designed like a heald frame and is additionally provided with vertical struts  9   a , which are arranged distributed over the length of the guide rail arrangement. The upper part of the frame structure is formed by the guide rail arrangement and the lower part by the longitudinal section  18 . This frame structure is particularly advantageous, since it has a low mass and the vertical forces which are exerted by the leno threads are distributed over the vertically acting drive elements without a disturbing deformation of the frame structure.  
     [0032] In the present exemplary embodiment the apparatus in accordance with the invention comprises a frame  6  which is designed in box shape, on which the needle bar  7 ,  7 ′ for the ground threads is arranged together with a deflection element  5  for the ground threads, which is vertically movably mounted and which is operatively connected to the dobby via at least two heald drive bars which depart from the dobby, with at least two of the heald drive bars being arranged spaced apart in the longitudinal direction of the ground and leno threads. In the exemplary embodiment the box shaped frame  6  is formed in the longitudinal direction by the needle bar  7 ,  7 ′ or its carrier respectively and through the longitudinal sections  14 . 1 ,  14 . 2 , and in the transverse direction by bridge-like elements  6   a , which are arranged distributed over the length of the frame. When required the frame can be provided with transverse struts for stiffening. Laterally arranged heald frame guides are used for the vertical guidance of the box shaped frame. The use of two or three heald frame guides, of which at least two are arranged with spacing in the longitudinal direction of the ground and leno threads, is advantageous. The described box shaped frame has a great stiffness with regard to both the vertical forces which are exerted by the ground threads and to the torque which acts on the needle bar and the deflection element.  
     [0033] During the weaving process the leno thread  3  is lifted in a first step into an upper position  3 ′ through a lifting of the guide rail arrangement  8  and the ground thread  4  is lowered into a lower position  4 ′ through a lowering of the needle bar  7  and then the leno thread  3 ′ is laterally displaced through the lateral displacement of the guide rail  8 , with the leno thread being moved from the one side of a ground lamella  7   a  to the other side. In the next step the leno thread is lowered into the intermediate space between the ground lamella  7   a  which lies beneath the displaced position and the ground thread is lifted into an upper position  4  for the purpose of forming a shed. In a further step the insertion of a weft thread  19  into the shed which is formed by the leno thread  3  and the ground thread  4  takes place. In the following step the inserted weft thread  19  is beaten up into the beat-up position  2  by a moving of the reed  2 ′. For the manufacture of a leno cloth the above steps are repeated, with the leno thread  3  being lowered alternatively in the initial position and in the displaced position into the respective intermediate space between the ground lamella  7   a  lying directly beneath it.  
     [0034] In a further advantageous embodiment, which is shown in FIG. 3, the apparatus comprises a plurality of rotatably journalled support levers  20  which are arranged distributed over the length of the needle bar  7  for the ground threads and to which the needle bar and the deflection element for the ground threads are connected, with a common axis of rotation, which is arranged with displacement in the longitudinal direction of the ground and leno threads  3 ,  4  from the needle bar for the ground threads and which, for example, can be executed as a through-going axle or as individual axle segments which lie along a line. Through the rigid connection between the support levers and the needle bar and the deflection element, disturbing twisting of the needle bar through the torque which acts on the needle bar and the deflection element are avoided.  
     [0035] In a further advantageous embodiment, which is shown in FIG. 4, the apparatus comprises a plurality of four-bar linkages, which are arranged distributed over the length of the needle bar  7  for the ground threads and which comprise the sides  21 . 1  through  21 . 4  with in each case two substantially vertically extending sides  21 . 3 ,  21 . 4 , one of said sides  21 . 3  being fixedly arranged in the weaving machine and one of said sides  21 . 4  being movable, with the movable side  21 . 4  being connected at one end to the needle bar  7  for the ground threads and at the other end to the vertically acting drive elements  16 . 1 ,  16 . 2 . Through the rigid connection between the movable side  21 . 4  and the needle bar and the deflection element, disturbing twisting of the needle bar through the torque which acts on the needle bar and the deflection element are avoided.  
     [0036]FIG. 5 a  shows a cross-section of an embodiment with a needle bar  7  for ground threads which is stationarily arranged in the weaving machine. The stationary arrangement of the needle bar for the ground threads has the advantage that no relative movement and thus also no abrasive friction arises between the needle eyes of the needle bar and the ground thread  4 . For this a larger vertical stroke of the guide rail arrangement  8 ,  8 ′ must be tolerated.  
     [0037]FIG. 5 b  shows in cross-section a frame structure  9  for holding the guide rail arrangement  8 ,  8 ′. The frame structure  9  is formed like a standard heald frame and is provided with additional vertical struts  9   a , which are arranged distributed over the length of the guide rail arrangement. The vertical struts  9   a  are preferably arranged in such a manner that they have a sufficient distance from the guide rail  8   a  in order to keep the lateral deflection of the leno threads low (cf. the horizontal section through a guide rail arrangement in FIG. 5 c ).  
     [0038] The apparatus in accordance with the invention can advantageously be used practically without a special adaptation in all current weaving machines which are equipped with a dobby, since as a rule a plurality of heald drive bar positions is in any case present. If, instead of simple cloths, leno cloths are to be manufactured with a weaving machine, then the weaving machine can be converted in a simple manner in that the normal, standard, heald frames are removed and replaced by an apparatus in accordance with the above described exemplary embodiment.  
     [0039] Since vertical drives are present both for the ground threads and for the leno threads in the apparatus in accordance with the exemplary embodiment, a simple cloth, for example a carpet cloth, can also be manufactured instead of a leno cloth with the same apparatus after a corresponding adaptation of the stroke rhythm and the stroke size. For this the needle bar is advantageously replaced by a kind of “eyed reed” (cf. item  7 ″ in FIG. 2 a ).