Abstract:
A device for the pneumatic splicing of yarns, especially elastane yarns, has a splicing body ( 25 ) defining a splicing conduit ( 26 ) loadable with compressed air, as well as with pneumatic tubes ( 33, 34 ) for pneumatically preparing the yarn ends ( 31, 32 ) to be spliced, wherein the central axes of the pneumatic tubes intersect the central longitudinal plane of the splicing conduit. The pneumatic tubes ( 33, 34 ) are replaceably fixed in bores ( 46, 47 ) of the splicing body ( 25 ), with the inlet opening ( 48, 49 ) of the pneumatic tubes ( 33, 34 ) positioned in the immediate vicinity of one of the two outlets ( 50, 51 ) of the splicing conduit ( 26 ). The inlet opening ( 48, 49 ) of the pneumatic tube ( 33, 34 ) has a funnel-shaped contour ( 52 ) that promotes insertion of the cut ends of the upper and lower yarns ( 31, 32 ) into the pneumatic tubes ( 33, 34 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application claims the benefit of German patent application DE P 102 02 781.1 filed Jan. 25, 2002, herein incorporated by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to a device for the pneumatic joining of yams, especially of elastane yams, and more particularly, to a splicing device comprising a splicing body having a splicing conduit for receiving the yarn ends and being loadable with compressed air for executing a splicing operation, and pneumatic tubes for preparing the yarn ends to be spliced.  
           [0003]    Yarn splicing devices for the pneumatic joining of yarns have long been known in conjunction with winding machines and have been described in detail, e.g., in German Patent Publications DE 40 05 752 A1 or DE 44 20 979 A1.  
           [0004]    Two yarn ends produced after a yarn break or a controlled cleaner step are pneumatically joined with these known yarn splicing devices in such a manner that a splice is created a joining site that is nearly equal to the yarn. That is, an upper yarn end, that typically has become wound onto the surface of the cheese in question, is taken up by a suction nozzle and placed into the splicing conduit of the splicing body of the yarn splicing devices. Almost simultaneously, the lower yarn end is retrieved by a grasper tube positioned in an unwinding position and likewise placed into the splicing conduit, where the upper yarn and the lower yarn are subsequently pneumatically joined.  
           [0005]    In order that the joinder of the two yarn ends at such a splice is approximately equivalent to the yarn and has approximately the same yarn strength, the two yarn ends must be exactly cut to length and prepared for the splicing process in advance.  
           [0006]    To this end, the known yarn splicing devices comprise appropriate yarn clamping devices, yarn cutting devices and pneumatic tubes for holding and opening the yarn ends in preparation for the splicing operation, sometimes referred to as holding and opening tubes. That is, the two yarn ends are also positioned between the holding cheeks of a yarn clamping device and between the cutting tool of one of the yarn cutting devices while they are threaded into the splicing conduit by the aforementioned manipulating elements. The yarn treatment devices for the respective yarn ends are arranged on opposite sides of the splicing conduit.  
           [0007]    When both the upper yarn and the lower yarn are reliably fixed in the associated yarn clamping devices the yarns are cut to length by the appropriate yarn cutting devices. The cut-to-length yarn ends are subsequently drawn by suction into the particular adjacent pneumatic tube and pneumatically prepared therein, i.e., the yarn ends initially are largely freed of their yarn twist and short fibers are removed. Subsequently, the prepared yarn ends are drawn by a so-called loop puller into the splicing conduit of the splicing body in such a manner that they rest at approximately the same height parallel to one another in the splicing conduit but with opposite alignment. A jet of compressed air introduced via corresponding inlet bores into the splicing conduit then assures an intermingling of the fibers of the two yarn ends, which yarn ends are at first resting substantially in parallel, with the result that a splice that is almost equal to the yarn is produced.  
           [0008]    The described method and the corresponding device have proven themselves in practice, e.g., when splicing pure cotton yarn or when splicing mixtures of cotton yarns and synthetic yarns.  
           [0009]    However, the situation becomes more difficult when splicing so-called elastane yarns that as a rule comprise a highly elastic core yarn surrounded other fibers, e.g., by cotton fibers. Such elastane yarns have the tendency, on account of the highly elastic core yarn, to contract strongly, that is, to strongly curl, after a yarn cut. If such elastane yarns are to be joined in one of the aforementioned yarn splicing devices, the problem frequently occurs that the yarn ends can not be drawn into the pneumatic tubes and appropriately prepared on account of their strong tendency to curl, or that the overlapping of the yarn ends within the splicing conduit of the splicing body of the yarn splicing devices is insufficient. In each case, the result is generally that either no splice can be made or the splice does not meet the quality requirements placed on it.  
           [0010]    In order to be able to splice elastane yarns, the suggestion has therefore already been made to arrange additional stopping means in the area of the splicing conduit or of the pneumatic tubes which fixes the yarn ends after they have been cut to length by the yarn cutting devices, i.e., the stopping means prevent the cut-to-length yarn ends from being able to curl too much.  
           [0011]    European Patent Publication EP 1,118,570 A2 shows and describes a yarn splicing device comprising an additional yarn stopping means in the form of a serrated sheet at the height of each pneumatic tube. These sheets, each of which fixes one of the yarn ends, are arranged midway between the actual yarn clamping device and the associated pneumatic tube. Thus, the free yarn length that is produced after cutting to length of the yarn ends by the yarn cutting device and that tends to curl is approximately halved by the known stopping means. The number of successful splicing joinings with elastane yarns was able to be slightly increased with a yarn splicing device designed in this manner; however, the basic problem could not be eliminated.  
           [0012]    This statement also applies, at least in part, to the yarn splicing device described in subsequently published German Patent Publication DE 101 24 832 A1. Even in this yarn splicing device, stopping means for the yarn ends are arranged approximately at the height of the pneumatic tubes which stopping means is effective to approximately halve the length of the cut-to-length yarn ends with a tendency to curl. The stopping means in accordance with German Patent Publication DE 101 24 832 A1 are designed as vacuum-loadable sieves that pneumatically fix the cut-to-length yarn ends on their surface.  
           [0013]    In addition, an embodiment is also shown and described in German Patent Publication DE 101 24 832 A1 in which the stopping means are positioned in the direct vicinity of the associated pneumatic tubes. Such an embodiment makes it possible to significantly raise the number of successful splices on elastane yarns. However, the yarn splicing devices according to German Patent Publication DE 101 24 832 A1 have the disadvantage that they are relatively complicated and therefore costly.  
           [0014]    Also, German Patent Publication DE 34 05 304 A1 teaches a yarn splicing device in which the splicing conduit arranged in the splicing body comprises flow conduits in addition to the customary openings for injecting compressed air. The flow conduits branch off laterally from the splicing conduit between the openings for injecting compressed air and the outlets of the splicing conduit and are each connected to an injector device. A flow of air directed away from the splicing conduit can be produced in the flow conduits by this injector device which flow of air is intended to assure when necessary that the cut-to-length yarn ends are drawn by suction into the flow conduits and that the yarn ends are pneumatically prepared.  
           [0015]    While these flow conduits branch off directly from the splicing conduit, the flow conduits are, however, very limited in their diameter. That is, the diameter of the flow conduits must, in order to guarantee the proper functioning of the splicing device, be clearly below the width of the corresponding splicing conduit. Due to this relatively small diameter of the flow conduits, the yarn splicing device in accordance with German Patent Publication DE 34 05 304 A1 has proven to be almost unusable in practice, especially if difficult yarns, e.g., relatively stiff yarn, is to be processed, since the small diameter of the flow conduits prevents the drawing in by suction of the customary yarn loop into the flow conduit.  
           [0016]    These known yarn splicing devices also have the disadvantage that the flow conduits are formed directly in the splicing body so that an individual adaptation of the flow conduits to changing yarn parameters is very difficult and, as a rule, requires replacing of the entire splicing body. For example, in the known yarn splicing devices, a replacement of the entire splicing body is always necessary, e.g., if the yarn number changes or if the yarn twist of the yarns to be processed changes, i.e., if a change is made from yarns with a Z twist to yarns with an S twist.  
           [0017]    Thus, to enable an individual adaptation of the holding and opening device to differing yarns, it is necessary to maintain a large stock in these known yarn splicing devices.  
         SUMMARY OF THE INVENTION  
         [0018]    In light of the above referenced state of the art, it is an object of the present invention to provide a device for pneumatically joining yarns that makes it possible, if required, to splice problematic yarns, e.g., elastane yarns, and in which the pneumatic tubes can be readily adapted to changing yarn parameters.  
           [0019]    The present invention addresses this objective by providing a device for the pneumatic joining of two yarn ends, wherein a splicing body has a splicing conduit extending between opposite conduit outlets for receiving the yarn ends and is loadable with compressed air for executing a splicing operation. Pneumatic tubes are provided for holding and opening the yarn ends in preparation to be spliced. The pneumatic tubes are replaceably fixed to the splicing body in an orientation wherein the pneumatic tubes have respective central axes which intersect a central longitudinal plane of the splicing conduit and respective inlet openings each disposed in the immediate vicinity of a respective one of the conduit outlets, each inlet opening of the pneumatic tubes being of a funnel shape to promote insertion of the yarn ends into the pneumatic tubes.  
           [0020]    The device in accordance with the invention has the particular advantage that the yarn ends of the upper yarn and of the lower yarn, that are fixed in yarn clamping devices arranged at a spacing from the splicing body above and below the yarn splicing device, are drawn by suction after having been cut to length by appropriate yarn cutting devices immediately into the pneumatic tubes arranged in the immediate vicinity of the outlets of the splicing conduit and are additionally fixed therein pneumatically. Even the typical curling of the yarn ends, e.g., the case of elastane yarns, is extensively avoided by the additional pneumatic fixing of the yarn ends which assures the production of correct splices in a simple and reliable manner.  
           [0021]    The funnel-shaped contour of the inlet opening of the pneumatic tubes assures that even such difficult yarns are reliably drawn in by suction. Since the pneumatic tubes are fixed in a replaceable manner in bores of the splicing body, an adaptation of the pneumatic tubes to the particular existing yarn parameters is also possible at all times so that an optimum preparation of the drawn-in yarn ends for the next splicing procedure can be achieved without great expense. The necessary inventory stock is limited thereby to the pneumatic tubes.  
           [0022]    An advantageous embodiment of the invention provides that the funnel-shaped contour is a component of a stopping means that is secured to the splicing body, e.g., by a readily accessible screw bolt, and fixes the associated pneumatic tube in a readily replaceable manner in a bore of the splicing body. Such a stopping means can be manufactured in a relatively easy and inexpensive manner, e.g., as a deep-drawn sheet part.  
           [0023]    Furthermore, a preferred embodiment of the invention provides that the pneumatic tubes are constructed in such a manner that the central axis of each pneumatic tube is oriented at the level of the bottom of the splicing conduit. This arrangement assures that the yarn ends fixed in the yarn clamping devices are tensioned centrally over the pneumatic tubes so that yarn ends are immediately loaded with the full suction pull of the pneumatic tubes, which has a very positive effect on the operational reliability of the pneumatic tubes.  
           [0024]    It is also preferred that both the injection openings arranged in the splicing conduit for blowing in compressed air as well as the pneumatic tubes are connected to a source of compressed air via pneumatic lines into which regulatable valves are placed. The valves, e.g., 2/2-way valves, are connected via appropriate control lines to the winding-head computer of the respective winding head and can in this manner be regulated in a defined fashion without a large, additional expense for their control being necessary. That is, the opening times of the valve for the pneumatic tubes and the opening times of the valve for the injection openings arranged in the splicing conduit can be exactly adjusted as needed and optimally adapted as needed.  
           [0025]    An advantageous embodiment provides that the introduction of compressed air into the pneumatic tubes for fixing the yarn ends and the introduction of compressed air into the splicing conduit for splicing the yarn ends overlap in time. Such an overlapping in time prevents the yarn ends of the upper yarn and of the lower yarn arranged in the splicing conduit from being able to curl and from leaving the splicing conduit at least partially before the splicing air is injected. That is, the loading of the pneumatic tubes with compressed air and therewith the additional pneumatic fixing of the yarn ends is maintained at least until it has been assured that the yarn ends have already been sufficiently joined to one another.  
           [0026]    Further details, features and advantages of the invention are explained in the following disclosure with reference made to an exemplary embodiment shown in the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]    [0027]FIG. 1 is a schematic side elevational view of a work station of a cheese producing textile machine which embodies the yarn splicing device of the present invention.  
         [0028]    [0028]FIG. 2 is a top plan view, partially in cross-section, of the yarn splicing device of the present invention.  
         [0029]    [0029]FIG. 3 is across-sectional view of the yarn splicing device of the present invention, taken along section line III-III of FIG. 2.  
         [0030]    [0030]FIG. 4 is a graph depicting the course in time of the pressure impulses acting in the splicing conduit and in the pneumatic tubes.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]    Referring now to the accompanying drawings in greater detail, FIG. 1 schematically shows a side view of a work station  1  of a textile machine that produces cheeses, more specifically an automatic cheese winder in the exemplary embodiment. Such textile machines normally comprise a plurality of such work stations  1  arranged in a row adjacent to each other. Spinning cops  2  produced, e.g., on ring spinning machines (not shown), are rewound at work stations  1  into large-volume cheeses  13 . Work stations  1  are provided to this end with various, schematically shown yarn manipulating devices and yarn checking devices as well as with their own control device, preferably in the form of a so-called winding-head computer.  
         [0032]    As is indicated in FIG. 1, yarn  3  drawn off from spinning cop  2  preferably travels on a normal winding path through unwinding accelerator  4 , yarn tensioner  6 , yarn cleaner  8  which has associated yarn cutting device  9 , and optionally through paraffining device  10 , to the cheese  13 , which is rotatably supported in creel  14  and is frictionally driven during the winding operation via a so-called grooved drum  12 .  
         [0033]    Furthermore, yarn splicing device  7  is arranged outside of this normal yarn winding path  30 .  
         [0034]    In order to manipulate the yarn ends in case of a yarn break or for a defined cleaner step, suction nozzle  15  for manipulating upper yarn end  31  and grasper tube  19  for manipulating lower yarn end  32  are provided. Suction nozzle  15  comprises vacuum-loadable mouth  16  and is supported in such a manner that it can rotate in a limited extent about pivot axis  17  to bring upper yarn end  31  to yarn splicing device  7 . Grasper tube  19  comprises vacuum-loadable suction opening  20  and is supported in such a manner that it can rotate in a limited extent about pivot axis  21  to bring lower yarn end  32  to yarn splicing device  7 .  
         [0035]    As FIG. 2 schematically indicates, yarn splicing device  7  of the present invention comprises air distributor block  24  arranged on the winding-head housing, on which block a so-called splicing prism or body  25  is fixed via screw bolts  23 . Splicing body  25  comprises, as is customary, splicing conduit  26  into which openings for blowing in compressed air  29  empty. Openings for injecting compressed air  29  are connected to compressed-air source  11  via pneumatic line  18  connected to air distributor block  24 , into which line a valve, e.g., 2/2-way valve  22  is inserted. Moreover, directional control valve  22  is connected for its part via control line  27  to winding-head computer  5  of the particular work station  1 .  
         [0036]    Furthermore, a pneumatic tube  33 ,  34  is arranged in the immediate vicinity of each of outlets  50 ,  51  of splicing conduit  26  in corresponding receiving bores  46 ,  47 .  
         [0037]    Pneumatic tubes  33 ,  34  are fixed in a replaceable manner by stopping means  53  with funnel-shaped contour  52  and are positioned in such a manner that central axes  37 ,  38  of pneumatic tubes  33 ,  34  are arranged at the level of bottom  55  of splicing conduit  26  and run orthogonally to central plane  45  of splicing conduit  26 . Stopping means  53  can be fixed, e.g., via screw bolts  54  to splicing body  25 .  
         [0038]    Pneumatic tubes  33 ,  34  comprise, as is customary, at least one tangential bore  56 ,  57  and are connected to compressed-air source  11  via pneumatic line  35  into which valve  36  has been inserted, and 2/2-way valve  35  can be controlled via control line  28  by winding-head computer  5 .  
         [0039]    As is also apparent from FIG. 2, yarn guide devices  39 ,  40 , yarn clamping devices  43 , 44  and yarn cutting devices  41 ,  42  are arranged on both sides of splicing body  25  in addition.  
         [0040]    The operation of the yarn splicing device of the present invention may thus be understood. During the winding operation, traveling yarn  3  is monitored by yarn cleaner  8 , schematically shown in FIG. 1, which cleaner detects each yarn irregularity and reports it to winding-head computer  5 . Winding-head computer  5  thereupon immediately initiates a defined yarn cut. That is, traveling yarn  3  is separated by yarn cutting device  9  into upper yarn end  31  and lower yarn end  32 . While upper yarn end  31  is wound onto the surface of cheese  13  while a braking force is applied, lower yarn end  32  remains held as a rule in yarn tensioner  6 .  
         [0041]    In order to clean out the damaged section of yarn and to establish a new yarn splice, upper yarn end  31  is unwound from cheese  13 . That is, suction nozzle  15  is pivoted upward, as indicated in FIG. 1 with dotted lines, and positioned with its vacuum-loadable mouth  16  in the area of the surface of cheese  13 . At the same time, cheese  13  is slowly rotated in the unwinding direction. As soon as suction nozzle  15  has aspirated upper yarn end  31 , the damaged yarn section is separated out and removed by a yarn cutting device (not shown) arranged in the range of suction nozzle  15 . Then the now defect-free upper yarn end  31  is threaded by suction nozzle  15  into splicing conduit  26  of splicing body  25  of yarn splicing device  7 , as FIG. 2 indicates. Suction nozzle  15  also positions upper yarn end  31  thereby in upper yarn clamping device  44  and between the tools of lower yarn cutting device  41 .  
         [0042]    The aspiration of lower yarn end  32  also takes place at the same time or somewhat offset in time from the aspiration of upper yarn end  31 . That is, grasper tube  19  retrieves lower yarn end  32 , that is fixed as a rule in yarn tensioner  6  after a controlled yarn cut, at yarn tensioner  6  and places it likewise into splicing conduit  26  of splicing body  25  of yarn splicing device  7 . As soon as the two yarn ends  31 ,  32  have been placed into splicing conduit  26  and mechanically fixed in yarn clamping devices  43 ,  44 , pneumatic tubes  33 ,  34  are loaded with compressed air by appropriately regulating valve  22 . Then, yarn ends  31 ,  32  are cut to length by yarn cutting devices  41 ,  42 .  
         [0043]    That is, winding-head computer  5  first regulates directional control valve  36  into an open position via signal line  28  so that a relatively strong suction intake flow is present in the area of inlet openings  48 ,  49  of pneumatic tubes  33 ,  34 . After the separation of the upper yarn and lower yarn ends  31 ,  32  by yarn cutting devices  41 ,  42 , at first the cut yarn ends are removed via suction nozzle  15  and grasper tube  19  and at the same time the free ends of upper yarn  31  and lower yarn  32  are drawn in by suction via funnel-shaped contour  52  of stopping means  53  into pneumatic tubes  33 ,  34 . The yarn ends of upper yarn and lower yarn  31 ,  32  are pneumatically fixed as a result thereof and thus prevented from curling too strongly. Furthermore, the yarn ends of the upper yarn and of the lower yarn are pneumatically prepared in accordance with the instructions by the compressed air flowing in via tangential bores  56 ,  57  of pneumatic tubes  33 ,  34 . That is, the yarn ends of the upper yarn and of the lower yarn drawn by suction into pneumatic tubes  33 ,  34  are largely freed of their yarn twist and of short fibers.  
         [0044]    The prepared yarn ends are then drawn by a so-called loop puller into splicing conduit  26  of yarn splicing device  7  and pneumatically joined therein, as is known and therefore neither shown nor explained in detail. That is, winding-head computer  5  regulates 2/2-way valve  22  in such a manner via signal line  27  that splicing air is blown into splicing conduit  26  via pneumatic line  18  and openings for injecting compressed air  29  which splicing air intermingles the fibers of the two yarn ends with each other, which fibers are at first arranged largely in parallel, thus producing a yarn splice.  
         [0045]    While the yarn ends are being drawn back by the loop puller into splicing conduit  26 , pneumatic tubes  33 ,  34  remain loaded by compressed air so that the yarn ends of the upper yarn and of the lower yarn are loaded with a pneumatic holding force in the direction of pneumatic tubes  33 ,  34  on account of the injector flow prevailing in pneumatic tubes  33 ,  34 .  
         [0046]    The injector flow in pneumatic tubes  33 ,  34  remains maintained thereby at least until the introduction of the first jet of splicing air into splicing conduit  26 .  
         [0047]    In a preferred embodiment, the pulse  58  of compressed air for fixing the yarn ends in pneumatic tubes  33 ,  34  is injected at a point in time of t 1 , as indicated in FIG. 4, and remains until the later point in time t 3 . On the other hand, the pulse  59  of compressed air for splicing the two yarn ends approximately equivalent to the yarn is present between times t 2  and t 4 . Thus, compressed air pulse  58  for splicing the yarn ends and compressed air pulse  59  for fixing the yarn ends in pneumatic tubes  33 ,  34  overlap in time.  
         [0048]    It will therefore be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those herein described, as well as many variations, modifications and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing description thereof, without departing from the substance or scope of the present invention. Accordingly, while the present invention has been described herein in detail in relation to its preferred embodiment, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended or to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications and equivalent arrangements, the present invention being limited only by the claims appended hereto and the equivalents thereof.