Abstract:
A centrifugal spinning machine having at least one spinning station ( 10 ), each of which has one rotatable spinning centrifuge ( 14 ), one yarn guide ( 18 ) that can be supplied with a fibrous spinning strand ( 26 ′), and one drive device ( 38 ) for generating an axial motion between the yarn guide ( 18 ) and the spinning centrifuge ( 14 ). The yarn ( 26 ) is guided in the yarn guide ( 18 ) to travel through the rotational axis of a rotor  46  of the drive device ( 38 ).

Description:
FIELD OF THE INVENTION 
     The present invention relates to a spinning machine and method for producing yarn by centrifugal spinning, also known as pot spinning. 
     BACKGROUND OF THE INVENTION 
     A centrifugal or pot spinning machine and method are known for instance from German Patent Disclosures DE 42 08 039 A1 and DE 43 24 039 A1. Such centrifugal spinning machines as a rule include many spinning stations, each of which has one rotatable spinning centrifuge. Such spinning stations are supplied with sliver via a sliver drafting device, preferably a drafting roller mechanism, from which the drafted sliver is spun into a yarn by the action of the spinning centrifuge as it rotates about its center axis. In the process, the yarn passes through a tubular yarn guide and emerges from its orifice, and therefrom the yarn is applied to the inner wall of the spinning centrifuge in layers, forming a so-called spinning cake. This deposition of the spinning cake is accomplished by generating a relative motion, also known as a shogging motion, between the yarn guide and the spinning centrifuge in the axial direction which is generated by a drive device for the yarn guide and/or for the spinning centrifuge. Once the spinning process is completed, or a predetermined amount of yarn is placed in the spinning centrifuge , the yarn cake spun to that time is wound onto a rewinding tube held in readiness on the yarn guide. 
     From German Patent Disclosure DE 41 02 549 A1, a ring spinning apparatus is known, with a drive device for generating an axial motion between a rotor revolving on a spinning ring and a yarn carrier disposed on a spindle roving frame. The drive device includes a lifting carriage, for instance, which can be shifted by a spindle arrangement. The spindles are driven preferably by an electric motor. In these known drive devices, it is disadvantageous that a relatively complicated arrangement has to be provided, which requires a relatively large amount of space. In addition, the drive spindles are located in an open exposed disposition where they tend to become heavily covered with lint and debris, especially in the environment of a spinning mill, and hence the spindles need a relatively large amount of maintenance. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the present invention to provide an improved centrifugal spinning apparatus and method which overcomes the aforementioned problems and disadvantages. More particularly, an object of the present invention is to provide a centrifugal spinning apparatus and method with which a relative motion can be attained between a yarn guide and a spinning centrifuge in a simple manner. 
     According to the invention, this object is attained by a centrifugal spinning machine having at least one spinning station comprising a rotatable spinning centrifuge, a yarn guide arranged to receive a fibrous spinning strand (e.g., a sliver, roving or the like), and a drive device for generating relative motion axially between the yarn guide and the spinning centrifuge for causing the fibrous spinning strand upon emerging from the yarn guide to be spun into a yarn and deposited on an inside wall of the spinning centrifuge in the form of a spinning cake. According to the present invention, the drive device includes a rotor disposed about a rotational axis and the yarn guide is oriented to cause the fibrous spinning strand guided thereby to travel through the rotational axis of the rotor of the drive device. 
     Because the yarn guided in the yarn guide runs through the rotational axis of the rotor of the drive device, a very compact design is possible. Thus, the provision of intermediate transmission members can be eliminated, which not only saves space but also considerably simplifies assembly. 
     Because of the reduction of the mass that has to be driven, the energy input for generating a relative motion between the yarn guide and the spinning centrifuge is minimized, which increases the effectiveness of the entire centrifugal spinning device. 
     In a preferred feature of the invention, the drive device is an electric motor, whose rotor is operatively connected directly to the yarn guide, and preferably the rotor is a cylinder, which receives the yarn guide by positive engagement. As a result, a transmission of the driving energy of the electric motor to the yarn guide is made possible in an especially simple way, since the rotor of the electric motor acts directly on the yarn guide. In particular, this makes a very precise positioning of the yarn guide possible, since tolerance errors, slip errors or the like are avoided because of the lack of intervening transmission members. 
     An advantageous embodiment is obtained if the rotor of the electric motor has internal teeth that mesh with external teeth of the yarn guide. This arrangement provides a secure, positive connection between the rotor and the yarn guide. The relative motion of the yarn guide with respect to the spinning centrifuge can be adjusted in an exactly replicable manner via the male thread of the yarn guide and the corresponding female thread of the rotor. 
     It is also a preferred feature of the invention that the electric motor is a stepping motor. As a result, by a suitable defined triggering of the stepping motor, an exact positioning or an exact axial shifting of the yarn guide relative to the spinning centrifuge can be achieved. A proportional shifting of the yarn guide is effected in accordance with the triggering of the stepping motor, so that the spinning cake deposited on the inside circumference of the spinning centrifuge is distinguished by a uniform yarn layer. 
     The invention also provides a novel and advantageous method of centrifugal spinning yarn. Because the yarn guided in the yarn guide travels through the rotational axis of a rotor of a drive device, and because the yarn guide is acted upon directly by a driving force to produce an axial motion, a very precise relative motion of the yarn guide to the spinning centrifuge can be attained. This direct engagement of the yarn guide by the driving force minimizes any positioning error during the relative motion of the yarn guide. As a result, the quality of the spinning cakes produced can be optimized to a high degree. 
     Further preferred features, characteristics and advantages of the present invention will be described and understood from a detailed disclosure of an exemplary embodiment of the invention with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view partially in side elevation and partially in vertical cross-section of a centrifugal spinning station according to a preferred embodiment o f the present invention; 
     FIG. 2 is an enlarged vertical cross-sectional view of the torsion preventer for the yarn guide of the centrifugal spinning station of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the accompanying drawings, a spinning station  10  of a centrifugal or pot spinning machine is shown schematically in FIG.  1 . Typically, centrifugal spinning machines have many such spinning stations  10 , which are disposed side by side either in rows or in rings. Each spinning station  10  has one centrifugal spinning device  12 , which is shown in FIG. 1 in a schematic longitudinal section. The centrifugal spinning device  12  includes a rotatably supported spinning centrifuge  14  into the interior  16  of which extends a yarn guide  18  such that the longitudinal axis  22  of the yarn guide  18  coinciding with the rotational axis  24  of the spinning centrifuge  14 . 
     A sliver or roving  26 ′ drafted in a drafting roller mechanism  32  can be introduced into the spinning centrifuge  14  by the yarn guide  18  and is then spun into a yarn  26  by the action of the rotating spinning centrifuge  14 . The yarn  26  emerges laterally from the yarn guide orifice as indicated at  28  and is deposited in the form of a so-called spinning cake on the inside wall  30  of the spinning centrifuge  14 . 
     The yarn guide  18  is equipped with a drive device  38 , by which is produced an axial relative motion of the yarn guide  18  and thus of its orifice  16  relative to the spinning centrifuge  14 . The relative motion of the yarn guide  18  is effected in a reciprocating fashion, commonly refined to as shogging, while at the same time the yarn guide  18  is progressively shifted downwardly somewhat so that the spinning cake  20  has the form of a so-called cop winding. 
     The drive device  38  is preferably embodied as a stepping motor  40 , which can be triggered via a control unit  42 . The stepping motor  40  includes a stator  44 , supported in stationary fashion, and a rotor  46  rotatably disposed inside the stator. The construction and mode of operation of stepping motors  40  are well known, and therefore need not be described in further detail herein. 
     The rotor  46  is embodied as a cylinder  48 , which has a female thread  50  which meshes with a male thread  52  of yarn guide  18 . The meshing threads  50  and  52  provide a positive connection between the drive device  38  and the yarn guide  18 . The yarn guide  18  itself is fixed against rotation by a torsion preventer  58 , which is shown in further detail in FIG.  2 . 
     The manner of operation of the centrifugal spinning device may thus be understood. During operation of the spinning station  10 , the spinning centrifuge  14  rotates at high speed (rpm) about the rotational axis  24  as a result of an electric motor drive device  64 . Simultaneously, sliver  26 , after being initially drafted for instance in the drafting mechanism  32 , is fed via the yarn guide  18  into the spinning centrifuge  14 . The drafted sliver, upon emerging from the orifice  36  of the yarn guide  18 , travels laterally in a revolving yarn segment  28  from the orifice  36  of the yarn guide  18  to the inner wall  30  of the spinning centrifuge  40  under the influence of the rotary motion of the spinning centrifuge  14  and in the process is spun into a yarn  26 , after which the yarn  26  is deposited against the inner wall  30  of the spinning centrifuge  14 , on which the deposited yarn  26  progressively forms a so-called spinning cake. 
     In order to form a spinning cake  20  that lends itself as well as possible to rewinding, the yarn  26  is deposited on the inner wall  30  of the spinning centrifuge  15  in the manner of a cop winding, i.e., the yarn guide  18 , in a manner known per se, is shogged back and forth constantly by a certain, constant stroke and at the same time is continuously shifted downward somewhat relative to the rotating spinning centrifuge  14 . As a result, the orifice  36  of the yarn guide  18  is likewise shifted relative to the inner wall  30  of the spinning centrifuge  14 , so that the region of contact of the yarn thread  28  varies accordingly. The yarn deposition technique described above, which leads to the formation of a spinning cake  20  that can be rewound well, is specified via the control unit  42 , which actuates the shogging motion of the drive device  38  according to a manual setting or a programmed setting via a microprocessor or other computation unit. 
     Depending on the triggering of the drive device  38 , preferably the stepping motor  40 , the cylindrical rotor unit  46 ,  48  is caused to rotate and, in turn, because of the positive connection between the female thread  50  of the rotor  46  and the male thread  52  of the yarn guide  18 , which is secured against rotation by a torsion preventer  58 , an axial shifting of the yarn guide  18  occurs. The torsion preventer  58  can, as indicated in FIG. 2, comprise a longitudinal groove  60  in the region of the male thread  52  of the yarn guide  18 , along with a securing element  62 . The securing element  62  is fixed against relative rotation on the stator  44  of the stepping motor  40 , and thus engages in the longitudinal groove  60 . 
     Because the drive device  38  virtually encompasses the yarn guide  18 , only an extremely small amount of space is needed to accommodate the drive device  38 . Moreover, in turn, the rotor  46  is effectively operationally connected directly to the yarn guide  18 . As a result, it is unnecessary to provide intermediate transmission members. The driving force can thus be initiated directly and precisely. At the same time, the drive device  38  takes on the function of the yarn guide  18  which is supported in quasi-floating fashion by the drive device  38 , so that there is no need to provide further bearings or the like. 
     The centrifugal spinning device  12  is also provided with a covering  54 , which is braced on one side on the drive device  38  and on the other on the upper end of the yarn guide  18 . The covering  54  has a substantially flexible cylindrical sheath  56 , for example, in the form of a bellows, which encompasses the yarn guide  18  above the drive device  38 . 
     The covering  54  assures that the positive connection between the yarn guide  18  and the drive device  38  is effectively sealed. As a result, lint, debris or the like that more or less necessarily occurs during the operation of the centrifugal spinning devices  12  is thusly prevented from settling upon the positive drive connection to impair the function of the drive device  38 . Because of the flexibility of the sheath  56 , the covering  54  can readily follow along with the reciprocating motion of the yarn guide  18 . The sealing is thus assured during every phase of operation of the centrifugal spinning device  12 . 
     In accordance with further exemplary embodiments, not shown, a non-positive connection between the drive device  38  and the yarn guide  18  can also be designed, for instance the drive device  38  may be embodied as a migrating shaft motor, whose actuator is in frictional engagement with the yarn guide  18 . As a result, here again, a direct transmission of the driving energy to the yarn guide  18  is made possible in a simple manner. 
     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.