Patent Publication Number: US-6209303-B1

Title: Arrangement and method for spinning a yarn

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This application claims the priority of German application 198 60 201.4, filed Dec. 24, 1998, the disclosure of which is expressly incorporated by reference herein. 
     The present invention relates to an arrangement for the spinning of yarn or thread from a plurality of yarn components, comprising 
     a drafting arrangement comprising a front roller pair feeding at least two yarn components, 
     a condensing zone downstream thereof through which all yarn components travel, 
     a stationary sliding surface provided in the condensing zone, which sliding surface comprises at least one suction slit which extends essentially in transport direction of the yarn components, 
     a perforated transport belt which transports the yarn components over the sliding surface, 
     a nipping roller defining the condensing zone on an exiting side by forming a nipping point, 
     and a ring spindle downstream thereof which twists all yarn components jointly. 
     An arrangement of this type is prior art in the international patent application WO 98/39505. Two fiber rovings are drafted in the drafting arrangement at close proximity to one another and thereafter condensed downstream of the drafting arrangement in the condensing zone. Subsequently, the drafted and condensed rovings can be fed to different ring spindles or to one common ring spindle. In the latter case, a so-called mock twist occurs. The transporting belt comprises two rows of holes, of which each one guides a fiber roving through the condensing zone. The end of the condensing zone is defined by a delivery roller pair, the transport belt being looped around one of the rollers. 
     A previously drafted but still twist-free fiber strand is bundled in the condensing zone, so that when it exits out of the condensing zone, that is at the last nipping point, a spinning triangle does not occur when the yarn components are subsequently twisted to form a yarn. The yarn is then less hairy and has an increased evenness and a greater tensile strength. As a result of a delivery roller pair being arranged downstream of the condensing zone, the suctioning of the yarn components to be condensed ends at a significant distance from the nipping point of the delivery roller pair. The condensed yarn components have thus disadvantageously the opportunity to expand again. Thus the actual aim of the condensing zone is only partially achieved. 
     It is an object of the invention to design the condensing zone arranged downstream of the front roller pair of the drafting arrangement, in particular when a plurality of yarn components are present, in such a way that the condensed yarn components retain their state until they reach the nipping point. 
     This object has been achieved in accordance with the present invention in that the nipping roller presses the yarn components and the transport belt to the sliding surface and in that the at least one suction slit extends up to the nipping point. 
     The nipping roller defining the condensing zone on its exit side no longer forms the nipping point with another roller, but rather with a stationary sliding surface, over which the transport belt is slidingly guided. The at least one suction slit can thus be extended to the end of the condensing zone, so that the condensing effect is not lost before the yarns reach the nipping point. The condensed effect is particularly homogenous when the transport belt is designed as a close-meshed woven belt. 
     The yarn components which are twisted together to form a yarn at the ring spindle can be of varying kinds. 
     For example, as in the above mentioned prior art, two fiber rovings can be guided each over one suction slit and are each condensed in the condensing zone before they are united at a yarn guide downstream of the nipping point. Slivers or rovings may be involved. Additionally, a core yarn can be added, which is fed by means of a feed roller arranged at the front roller pair of the drafting arrangement. Alternatively it is possible to guide only one sliver or roving through the condensing zone and to unite it with one single core yarn. 
     The yarn to be twisted at the ring spindle can thus either be created from two slivers or rovings, each with or without a core yarn, or be formed from one sliver or roving and a core yarn. 
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a part sectional side schematic view of an arrangement in an area of a condensing zone, constructed according to preferred embodiments of the present invention; 
     FIG. 2 is a view in the direction of the arrow II of FIG. 1, showing an arrangement whereby to facilitate the drawing illustration some components have been omitted, showing a yarn formed from two slivers or rovings; 
     FIG. 3 is a view similar to FIG. 1, showing an arrangement whereby a core yarn has been added to the slivers or rovings; 
     FIG. 4 is a view in the direction of the arrow IV of FIG. 3, whereby to facilitate the drawing illustration some components have again been omitted; 
     FIG. 5 is a view similar to FIG. 4 showing another embodiment, in which a sliver or roving as well as a core yarn have been united to form one yarn; and 
     FIG. 5A is a view similar to FIG. 5 showing another embodiment, similar to FIG. 5, but with the suction slit of the condensing zone angularly inclined with respect to the sliver travel direction from the drafting arrangement. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The arrangement shown in FIGS. 1 and 2 comprises a drafting arrangement  1 , a condensing zone  2  arranged downstream thereof as well as a ring spindle  3 . These parts are important components of a spinning station, of which a plurality are arranged adjacently in a row in an operating machine. 
     Of the drafting arrangement  1 , only the front roller pair  4  and the apron roller pair  5  arranged upstream thereof are shown. The front roller pair  4  comprises a front bottom cylinder  6  extending in machine longitudinal direction, to which one front top roller  7  is arranged per spinning station. In a way not shown, two front top rollers  7  of adjacent spinning stations can be joined together to form top roller twins. The front bottom cylinder  6  forms a front nipping line  8  together with the respective front top roller  7 . Between the apron roller pair  5  and the front roller pair  4 , the fiber material to be drafted is fed by bottom aprons  9  and top aprons  10  in a known way. 
     In the embodiment shown in FIGS. 1 and 2, two slivers or rovings  11  and  12  are fed to the drafting arrangement  1  in transport direction A, the slivers or rovings  11  and  12  travelling closely adjacent to one another through the drafting arrangement  1 . Thus four slivers or rovings altogether are arranged at each of the top roller twins. 
     At the front roller pair  4 , the slivers or rovings  11 , 12  are drafted to as yet untwisted fiber strands  13  and  14 , which then travel through the condensing zone  2  to a nipping point  15 . The nipping point  15  defines the condensing zone  2  at its exit side. From the point of the nipping point  15  onwards, two condensed yarn components  16  and  17  per drafting arrangement  1  are present, which are subsequently united to a single yarn  18 . The yarn  18  is fed in the delivery direction B to the ring spindle  3 . 
     A perforated transport belt  19  serves for the transport of the drafted, but as yet twist-free fiber strands  13  and  14  through the condensing zone  2 , which transport belt  19  consists of a very thin woven belt and which is very close-meshed. The woven belt consists preferably of plastic fibers, so that it can be joined to form an endless transport belt  19  and its lateral edges can be welded. The transport belt  19  transports the fiber strands  13  and  14  over an exterior sliding surface of a hollow profile  20 , which is designed as a suction device and which extends over a plurality, for example six or eight, spinning stations. A suction source  21  is preferably arranged at each hollow profile  20 , so that per machine section there is one suction source  21 . 
     Two suction slits  22  and  23 , parallel to one another, are arranged on the sliding surface of the hollow profile  20 , one of the suction slits  22  and  23  in each case being arranged at a fiber strand  13  or  14 . The suction slits  22  and  23  are significantly wider than the bundled yarn components  16  and  17 . They extend essentially in transport direction A, begin shortly after the front roller pair  4  and extend up to the nipping point  15 . The latter is particularly important, so that the condensing effect is not lost before the yarn reaches the nipping point  15 . 
     The nipping point  15  is formed by means of a nipping roller  24 , which presses the condensed yarn components  16  and  17  as well as the transport belt  19  against the sliding surface of the hollow profile  20 . The nipping roller  24  is driven by the front top roller  7  by means of a transfer roller  25 , so that the peripheral speeds at the front top roller  7  and at the nipping roller  24  are essentially the same. The peripheral speed at the nipping roller  24  should only be that much higher as to allow a slight tension draft to be exerted on the fiber strands  13  and  14 . 
     The front top rollers  7  as well as the nipping rollers  24  of each of the top roller twins are arranged in a rocker  26 , which is supported in turn in the top arm  28  of the drafting arrangement  1  by means of a loading spring  27 . 
     The condensed yarn components  16  and  17  are united at a yarn guide  29  arranged downstream of the nipping point  15 . At the point of union a wear-resistant ceramic insert  30  is provided, which, however, permits the spinning twist through to the nipping point  15 . The yarn guide  29  is connected to a suction tube  31  in a known way. From here the united yarn components  16  and  17  are guided as a single yarn  18  via a balloon yarn guide  32  to the ring spindle  3 . 
     In the present case, a so-called spin-twist or also mock twist subsequently arises from the two fiber strands or rovings  11  and  12 . 
     A cleaning tube  33  can be arranged at the transport belt  19  on the side facing away from the condensing zone  2 , which cleaning tube frees the transport belt  19  from any adhering fiber fly. A recess  34  of the hollow profile  20  is arranged at the cleaning tube  33 , so that the cleaning is more easily facilitated. 
     The embodiment of the present invention according to FIGS. 3 and 4 differs from the embodiment of the present invention shown in FIGS. 1 and 2 essentially in that a core yarn  35  is added in feed direction C in the center between the fiber slivers or rovings  11  and  12 . The core yarn  35  is fed to the drafting arrangement  1  at the front roller pair  4 . A feed roller  36  is provided for this purpose, which comprises a peripheral groove  37  for the core yarn  35 , by means of which groove  37  the core yarn  35  is centrically positioned. Two feed rollers  36  are connected with one another by means of an axle  38  to form twin rollers. 
     As the core yarn  35  consists usually of endless filaments, the core yarn  35  does not really need to be condensed. For this reason it is provided that the core yarn  35  travels centrically between the two suction slits  22  and  23  through the condensing zone  2  and is only then united with the condensed yarn components  16  and  17  downstream of the nipping point  15 . The point of union here lies at the yarn guide  29 . 
     The present invention includes also an embodiment according to FIG. 5, in which only one fiber sliver or roving  11  is transported in transport direction A by the drafting arrangement  1 , whereby a single core yarn  35  is added to this sliver or roving  11  which yarn  35  is fed in feed direction C. The condensing zone  2  comprises in this case only one suction slit  22 . The core yarn  35  is here also guided by means of the peripheral groove  37  of a feed roller  36  and is united at the front nipping line  8  of the front roller pair  4  with the sliver or roving  11 . Both yarn components, namely the drafted, still twist-free fiber strand  13  as well as the core yarn  35  are guided in this embodiment of the present invention over the suction slit  22  and are pressed at the end of the condensing zone  2  by the nipping roller  24  to the sliding surface of the hollow profile  20 . The arising yarn  18  is in this case a normal core yarn, which is, however, less hairy than standard core yarns. 
     FIG. 5A shows another preferred embodiment which is similar to FIG. 5, except for the angular inclination of the slit  22 A with respect to the travel direction of the sliver exiting the drafting arrangement. In FIG. 5A, the same reference numerals as in FIG. 5, with the suffix “A” are used to indicate corresponding features of FIGS. 5 and 5A. Other than the angularly inclined orientation of the suction slit  22 , the description of correspondingly numbered parts from FIG. 5 apply. 
     Embodiments are also contemplated which are similar to the above described embodiments of FIGS. 1-4, but with the suction slits of the condensing zone angularly inclined as depicted for the embodiment of FIG.  5 A. In these embodiments, the angular inclination of the two slots would be toward a central location leading to the yarn guide  29 . 
     The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.