Abstract:
A creel loading and relieving device for a winding device of a textile machine producing crosswound bobbins adjusts the contact pressure of a take-up bobbin mounted in a creel on a driving roll. The creel loading and relieving device comprises a creel pivotally mounted via a creel shaft and a force applying means which grips the creel and is adjustable via a positioning element. The creel loading and relieving device ( 30 ) has an actuator ( 33 ) that can be positioned by an electromotive drive ( 40 ) while a force applying means ( 29 ) which impinges upon the creel ( 9 ) is disposed on said actuator ( 33 ). The force applying means is configured as a pneumatic spring ( 29 ) and is hinged to a first lever arm ( 25 ) connected to a creel yoke ( 24 ). The loading or relieving moment applied to the creel ( 9 ) by the pneumatic spring ( 29 ) can be adjusted with precision by positioning the actuator ( 33 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of German patent application 10 2004 032 514.6, filed Jul. 6, 2004, herein incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to a creel loading and relieving device for a winding device of a textile machine producing cross-wound bobbins. 
         [0003]    Creel loading and relieving devices of this type substantially fulfill two objects during the production of a take-up bobbin. On the one hand, at the beginning of the bobbin travel, they should ensure minimum contact pressure of the tube or the still relatively light take-up bobbin on the associated drive roller, and on the other hand, during the bobbin travel, they should counteract the bobbin weight that is growing as the take-up bobbin becomes larger. 
         [0004]    As the contact pressure, in addition to the thread tension, determines the density of the take-up bobbin, generally a cross-wound bobbin, the aim is to keep the contact pressure as constant as possible during the entire bobbin travel. 
         [0005]    A creel loading and relieving device is known from German Patent Publication DE 25 18 646 C2, in which a creel mounting the cross-wound bobbin is arranged above a drive roller in such a way that the weight of the creel and the weight of the cross-wound bobbin act in the direction of the drive roller. The contact pressure of the cross-wound bobbin on the drive roller is additionally amplified at the beginning of the bobbin travel by a combined loading and relieving element, preferably by a compression spring which engages on a lever lug of the creel and is supported on an adjustment bracket. 
         [0006]    In other words at the beginning of the bobbin travel, the action line of the compression spring is located behind the creel shaft in such a way that an additional torque in the sense of “increasing the contact pressure” firstly becomes effective on the creel. As the diameter of the cross-wound bobbin becomes larger, the creel pivots into a position, in which the action line of the compression spring points precisely through the pivot axis of the creel. In this position, the spring force of the loading and relieving element is neutralized. As the diameter grows, the action line of the compression spring then migrates in front of the pivot axis of the creel, in other words, the creel is now acted upon with a torque in the sense of “relieving the creel.” 
         [0007]    The described creel loading and relieving device has been successful, in a slightly modified embodiment, in practice and a large number have been used for a long time. 
         [0008]    The drawback in this device is, however, that the contact pressure of the individual winding heads is adjusted centrally via a continuous adjustment rail, which constantly slightly elongates or shortens on temperature fluctuations. It is thus hardly possible to adjust uniform contact pressures at the individual winding heads of the textile machine with a continuous adjustment rail of this type, which pivots an adjustment bracket for the compression springs arranged there in the region of the winding heads. 
         [0009]    Furthermore, creel loading and relieving devices are known, for example from German Patent Publications DE 39 11 854 C2, DE 41 21 775 A1 or DE 41 11 617 A1, and operate in each case with a pneumatically loadable thrust piston gearing. 
         [0010]    German Patent Publication DE 39 11 854 C2 describes a contact pressure control device, which has a take-up bobbin diameter detection device, a contact pressure correction determining device and a pneumatic drive device. In other words, in this known winding device, the instantaneous diameter of the cross-wound bobbin is initially determined by calculation from the rotational speed ratio of the drive roller and cross-wound bobbin and the known diameter of the drive roller. Taking into account a predetermined contact pressure correction curve, the contact pressure of the cross-wound bobbin on the drive roller is then adjusted by means of a pneumatic thrust piston gearing, which engages on an arm of the creel. 
         [0011]    Various, different embodiments for a control device for adjusting the contact pressure of a winding device are known from German Patent Publication DE 41 21 775 A1. In all the embodiments, both a mechanical loading element and a pneumatic cylinder engage on the creel. One embodiment, in this case, describes, for example, a double-acting pneumatic cylinder, which is connected to two compressed air ductwork systems, which in each case have a different pressure level. By targeted loading of the pneumatic cylinder, in other words, depending on the piston side, which is loaded with pressure, and on the level of the pressure, which is provided on the piston, the creel can then be more or less loaded or relieved. 
         [0012]    German Patent Publication DE 41 11 617 A1 describes a device for controlling the contact pressure in a winding device, which has a length-adjustable lever arm fixed to the creel. The piston rod of a working cylinder is articulated to this lever arm via a joint, which is equipped with jockey rollers. The jockey rollers are provided, in each case in a replaceable control link, via the shape of which the contact pressure of the take-up bobbin can be adjusted on its drive roller. 
         [0013]    A creel loading and relieving device is also known from German Patent Publication DE 195 34 333 A1, which has both a thrust piston gearing and a mechanical force introduction means engaging on the creel. The trust piston gearing, in this case, acts as a damper cylinder during the normal winding operation and can also be used if necessary as a drive to lift the cross-wound bobbin from the drive roller. The mechanical force introduction means acting on the creel consists of a first tooth segment which is connected so as to be rotationally engaged with the creel and meshes with a second tooth segment, which is in turn arranged on a lever element, which is mounted so as to be rotatable to a limited extent in the winding head housing. A tension spring, which is connected with prestressing to an adjustment lever, which can be fixed in various positions on the winding head housing, engages on this lever element. In other words, the direction of action of the tension spring and therefore the level of loading of the creel or the contact pressure, can be adjusted via the position of the adjusting lever, for example to produce soft, average or hard cross-wound bobbins. 
         [0014]    The above-described creel loading and relieving devices are either very complex and therefore expensive or were not completely convincing in practice with regard to their function. 
       SUMMARY OF THE INVENTION 
       [0015]    Proceeding from creel loading and relieving devices of the type described above, the invention is based on the object of improving devices of this type. In other words, providing a creel loading and relieving device, which is configured such that the contact pressure of each winding head can be adjusted easily and with precision in a simple manner and in that, in addition, a correction of the adjusted contact pressure is possible at any time, if necessary, without problems. 
         [0016]    This object is achieved according to the invention by a creel loading and relieving device for a winding device of a textile machine producing cross-wound bobbins, adapted for adjusting the contact pressure of a take-up bobbin mounted in a creel on a drive roller. The device comprises a creel, which is pivotally mounted by a creel shaft, and a force introduction means, which engages on the creel and can be adjusted via an adjusting element. According to the invention, the creel loading and relieving device has an actuator which can be positioned by means of an electromotive drive. A force introduction, which acts upon the creel and is configured as a pneumatic spring, is arranged on the actuator. The pneumatic spring is articulated to a first lever arm that is connected to a creel yoke and the loading or relieving moment to be applied to the creel by the pneumatic spring can be adjusted with precision by positioning the actuator accordingly. 
         [0017]    Advantageous further configurations, features and advantages of the invention are described more fully hereinafter. 
         [0018]    The embodiment according to the invention of a creel loading and relieving device thus offers the advantage that the size and also the direction of action of an additional moment, which is applied to the creel by a force introduction means supported on the actuator, can be adjusted in a simple and very precise manner by a defined displacement of an actuator. In a preferred embodiment, the force introduction means is configured as a pneumatic spring. In other words, a pneumatic thrust piston gearing is articulated, for example, by its cylinder housing to an abutment of the actuator and by its piston rod to a lever arm which is connected so as to be rotationally engaged with the creel. 
         [0019]    With the embodiment according to the invention, it is not only possible to adjust the contact pressure according to the present material and the desired density of the take-up roller with precision and to keep it virtually constant during the entire bobbin travel, but it is also possible to work with a bobbin contact pressure which changes in the course of the bobbin travel. In this case, only the position of the actuator, to which the force introduction means is fastened, has to be adjusted. Preferably, the actuator in this case can be positioned without problems in any desired position by means of an electromotive drive within a predetermined adjustment range and therefore the additional loading or relieving moment, which is to act on the creel, in each case, can be adjusted sensitively and so that it can be reproduced. This means, that the bobbin contact pressure can be flexibly adapted to the respective existing winding conditions by the device according to the invention and hard, average or soft cross-wound bobbins can selectively be produced if necessary. 
         [0020]    According to one feature of the invention, the electromotive drive is preferably connected to the actuator via a self-locking worm gear. A self-locking worm gear of this type has the advantage, for example, that no electrical energy is necessary during the winding operation to fix the position of the actuator. Worm gears of this type, known per se, are also very compact with regard to their structure, which is important in view of the confined space conditions, operate virtually free of play and are distinguished, in addition, by a long service life. 
         [0021]    In an advantageous configuration, the actuator, according to another feature of the invention, is configured as a segment of a circle-like, preferably hollow component and, on its outer region, has worm gear teeth. Arranged inside the actuator is an abutment, on which the force introduction means is supported when loading the creel. The worm gear teeth in this case mesh with a drive worm of the worm gear which is fixed so as to be rotationally engaged on the motor shaft of the electromotive drive. As worm gears of this type are generally self-locking and have a high transmission ratio of, for example 40:1, the drive can be relatively small and therefore economical to position the actuator despite the high moment, which is transferred to the creel via the force introduction means. In other words, a conventional commercial stepping motor with a relatively small size is sufficient to position the adjusting member precisely, which is mounted so as to be rotatable to a limited extent about the pivot axis of the creel, and to fix it there. 
         [0022]    According to a further feature of the invention, the thrust piston gearing acting as a pneumatic spring is connected to the machine&#39;s own compressed air ductwork system via a pneumatic line. 
         [0023]    The connection here is designed such that the pressure, with which the pneumatic spring is prestressed, is constantly at a predeterminable, constant pressure level. In other words, the pneumatic line connected to the piston cavity of the pneumatic thrust piston gearing has a check valve, which ensures that the pressure, with which the pneumatic spring is prestressed, is always at a predeterminable, constant pressure level. The pneumatic thrust piston gearing thus loads the creel, depending on the position of the adjusting member, with a moment, which can be easily adjusted via its direction of action both with regard to its size and also with regard to its basic action (loading or relieving) and can optionally be connected at any time. 
         [0024]    According to another feature of the invention, a so-called damper cylinder engages on a further lever arm of the creel. A damper cylinder of this type already very substantially suppresses in the initial stages, oscillations, which occur owing to the cross-wound bobbin revolving on the drive roller and this has a very advantageous effect overall on the running quietness of the winding device and therefore on the bobbin structure of the cross-wound bobbin. 
         [0025]    The damper cylinder may also be activated in a defined manner if necessary. The entering piston rod of the damper cylinder then lifts the cross-wound bobbin from the drive roller. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0026]    The invention will be described hereinafter in more detail with the aid of an embodiment shown in the drawings, in which: 
           [0027]      FIG. 1  schematically shows, in a side view, a workstation of a textile machine producing cross-wound bobbins with a spinning device and a winding device with a creel loading and relieving device, 
           [0028]      FIG. 2  shows the winding device according to  FIG. 1  with a creel loading and relieving device according to the invention to an enlarged scale, also in a side view, 
           [0029]      FIG. 3  perspectively shows the creel with an associated creel loading and relieving device partially in section. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    One half of a textile machine producing cross-wound bobbins, in the embodiment, an open end rotor spinning machine, is shown in  FIG. 1  and designated as a whole by the reference numeral  1 . Open end rotor spinning machines of this type have, as is known, a large number of similar workstations  2 , which are arranged next to one another in the longitudinal direction of the machine. The workstations  2  in this case have a spinning device  3  and a winding device  4 . The fiber band  6  presented in spinning cans  5  is spun in the spinning devices  3  into threads  7 , which are then wound on the winding devices  4  to form cross-wound bobbins  8 . 
         [0031]    As indicated in  FIG. 1  and described in more detail below with the aid of  FIGS. 2 and 3 , the winding devices  4  are equipped, in each case, with a creel  9 , which is acted upon by a loading and relieving device  30 . An empty tube  10  or a cross-wound bobbin  8  is rotatably mounted in the creel  9  and driven in a frictionally engaged manner via a drive roller  11 . Furthermore, workstations  2  of this type in each case have a thread draw-off device  19  and a thread traversing device  18 . 
         [0032]    The open end spinning machine  1  also has a bobbin transporting device  12  arranged between the workstations  2  to dispose of finished cross-wound bobbins  8 . 
         [0033]    A movable service unit  16  is arranged at or on the spinning machine  1 , on a guide rail  13  and on a support rail  15 . Service units  16  of this type patrol along the open end spinning machine  1  and engage automatically when a handling requirement occurs at one of the workstations  2 . A handling requirement of this type exists, for example, when a full cross-wound bobbin  8  has to be exchanged for a new empty tube  10  at one of the workstations  2  and then has to be repieced. The service unit  16 , for this purpose, as known, has numerous handling devices, which allow a proper cross-wound bobbin/empty tube change. 
         [0034]      FIG. 2  shows in a side view and, to a relatively large scale, the winding device  4  of a workstation  2  of a textile machine  1  producing cross-wound bobbins. The winding head housing of the workstation  2  has the reference numeral  21  here. Fixed so as to be rotatable to a limited extent on this winding head housing  21  is, as conventional, a creel  9 , between the creel arms of which an empty tube  10  (see  FIG. 3 ) or the tube of a cross-wound bobbin  8  is rotatably mounted in tube receiving plates  22 . The tube  10  rests in this case on the drive roller  11  and is entrained thereby via frictional engagement. 
         [0035]    The creel  9 , as can be seen in particular from  FIG. 3 , is pivotably mounted via a creel yoke  24 , which has two bearing points and two lever arms  25  and  39  directed to the rear, on a creel shaft  23 , which is in turn fixed in the winding head housing  21 . As shown in  FIGS. 2 and 3 , a damper cylinder  42  supported on the winding head housing  21  is articulated to the lever arm  39  via its piston rod  43  and minimizes oscillations occurring during the winding operation in the region of the creel  9 . The damper cylinder  42 , which is connected to the pneumatic ductwork system (not shown) of the open end spinning machine  1  via a pneumatic line  44 , can be activated if necessary such that the cross-wound bobbin  8  is lifted from the drive roller  11 . 
         [0036]    As can be seen from  FIG. 3 , the lever arm  25  is acted upon by a force introduction means  29  of a creel loading and relieving device  30  characterized as a whole by the reference numeral  30 . In other words, the lever arm  25  has, apart from a bearing point  26 , which has the creel shaft  23  passing through it, a rear connection bore, in which a bolt  27  is fixed. The bolt  27  in this case forms a thrust bearing for the force introduction means which is configured as a pneumatic spring  29  and is also supported on an abutment  32  of the actuator  33 , the actuator  33  being rotatably fastened in turn to the creel shaft  23  via a bearing point  34 . 
         [0037]    The actuator  33 , apart from the abutment  32  for the pneumatic spring  29  also has a tooth segment  35  with worm gear teeth. 
         [0038]    This tooth segment  35 , with a worm  37 , which is fixed on the motor shaft  41  of an electromotive drive, preferably a stepping motor  40 , forms a worm gear  36 , which, as is conventional in gearings of this type, has a relatively large ratio and is self-locking. 
         [0039]    As can be seen from  FIG. 3 , the pneumatic spring, which is formed by a pneumatic thrust piston gearing  29 , is connected between the lever arm  25  of the creel  9  and the actuator  33  such that by corresponding activation of the stepping motor  40 , the position of the actuator  33  and therefore also the direction of the force component, which acts by means of the pneumatic spring  29  on the creel  9 , can be adjusted in a defined manner. In other words, by corresponding positioning of the actuator  33  by the electromotive drive  40 , both the direction of rotation and the engagement angle, at which the force component of the pneumatic spring  29  engages on the lever arm  25 , can be predetermined and therefore the contact pressure of the cross-wound bobbin on the drive roller  11  can be adjusted in a defined manner. This additional moment generated via the force component of the pneumatic spring  29  can be adjusted in this case either at the beginning of a bobbin travel and kept constant as far as possible during the bobbin travel or, if necessary, sensitively changed retrospectively if necessary in the course of the bobbin travel, in other words corrected. 
         [0000]    Functioning of the device: 
         [0040]      FIGS. 2 and 3  show, for example, the starting position at the beginning of a bobbin travel. In the present embodiment, the actuator  33  is positioned such that the contact pressure is as low as possible, in other words, in the course of the bobbin travel, cross-wound bobbins  8  which are as soft as possible are wound. Owing to the stepping motor  40 , the actuator  33  is positioned in a position in which the force component of the pneumatic spring  29  engages just above the creel shaft  23 . This means the force component firstly acts upon the lever arm  25  in the clockwise direction resulting in a torque which initially slightly increases the contact pressure of the empty tube  10  on the drive roller  11 . This torque, in addition to the weight of the creel  9 , initially ensures that the empty tube  10  is pressed with an adequate contact force on the drive roller  11 . The contact pressure of the empty tube  10  generated by the torque on the drive roller is selected in this case such that the empty tube  10  driven by the drive roller  11  via frictional engagement revolves very substantially free of slippage. 
         [0041]    As the cross-wound bobbin diameter grows, the creel  9  pivots in the direction of the arrow S ( FIG. 2  or  3 ) about the creel shaft  23 . The lever arm  25  and the pneumatic spring  29  connected to the lever arm  25  are thus also moved. In other words, the pneumatic spring  29  is pivoted downwardly about its abutment  32  on the actuator  33  as the fulcrum. The force component of the pneumatic spring  29  migrates in this case toward the creel shaft  23 , with the decisive length of the lever arm  23  for the size of the effective torque becoming shorter. At the instant at which the force component of the pneumatic spring  29  runs through the creel shaft  23 , the effective length of the lever arm  25  is zero. This means that at this instant no torque coming from the pneumatic spring  29  is effective. The cross-wound bobbin  8  which continues to grow during the course of the bobbin travel, pivots the creel  9  further in the direction S and therefore the lever arm  25  further downwardly. The force component of the pneumatic spring  29  thus also migrates further downward. 
         [0042]    This means that after passing through the above-described neutral position (force component passes through the creel shaft  23 ), the force component of the pneumatic spring  29  again brings about a torque on the lever arm  25 , which is now effective but in the anti-clockwise direction, however. This torque that is effective in the anti-clockwise direction on the lever arm  25  now ensures that a moment which is effective counter to the bobbin and creel weight is present at the creel  9 . As the effective length of the lever arm  25  constantly becomes greater as the bobbin diameter grows, the effective torque also increases in the course of the bobbin travel, so the increasing weight of the cross-wound bobbin  8  is automatically compensated.