Abstract:
A textile drafting system which is composed of a pair of coaxially mounted and rotatably driven lower rollers mounted to the frame of a textile processing unit, and a pair of upper rollers mounted adjacent the free end of a pivotally mounted weighting arm so that the upper rollers press downwardly against the lower rollers. A pair of clearer rollers are also mounted to the weighting arm so as to engage the upper rollers. The upper rollers and the clearer rollers are mounted to a common bracket which is adjustable along the length of the arm to accommodate different staple fiber lengths in the yarn which is being processed, and the upper rollers and the clearer rollers can be jointly moved with the bracket along the weighting arm without additional adjustment of the upper rollers and clearer rollers with respect to each other.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     The present application is a continuation of international application PCT/EP2003/011244, filed 10 Oct., 2003, and which designates the U.S. The disclosure of the referenced application is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to a drafting system for textile spinning units, and particularly to a roller mounting assembly for such a system.  
         [0003]     The fiber material being spun is normally fed to the spinning units in the form of rovings or feed yarns, which advance through a drafting system upstream of the spinning unit. During the spinning operation, waste fibers may wrap in an undesired manner about the rollers or cylinders of the drafting systems. If fiber material adhering to a drafting roller separates and enters the path of the advancing roving, which is also referred to as a yarn track herein, undesired knots or thick places may result in the roving and subsequently lead to intolerable imperfections in the yarn. It is therefore common to remove waste fibers from the drafting rollers by means of clearer rollers. The clearer rollers are rotated by frictional engagement with the operating rollers of the drafting system, and provided with a covering.  
         [0004]     DE 44 29 671 C1 discloses an upper roller support arm with an alternative design of a mounting support for the upper rollers. The upper rollers are supported in so-called steering members, which are mounted for longitudinal displacement and locking engagement in the upper roller support arm. The weighting of the upper rollers occurs by means of a tubular pressure element, which receives compressed air from a source of compressed air. All steering members can be biased via pressure plates with a weighting pressure. The disclosed mounting support is used exclusively for supporting the upper rollers.  
         [0005]     EP 0 344 944 A1 discloses a drafting system, in which the upper roller support and weighting arm comprises a plurality of upper rollers with associated clearer rollers. In the operating position, the upper rollers are moved toward the lower rollers and weighted down. In this connection, they form with the lower rollers nip lines. The upper roller support and weighting arm mounts on each side clearer rollers, which each extend over only one yarn track. Upper rollers and clearer rollers are each provided with separate mounting supports. The upper rollers are mounted on holding arms, which are supported in the interior of the U-shaped, downwardly open upper roller support and weighting arm for pivoting about horizontal axles. A pivotal support of this type requires a large space in the upper roller support and weighting arm. The installation of pneumatic pressure elements in the upper roller support and weighting arm, which permit weighting and relieving the upper rollers both in a uniform and simple manner, is not possible or possible only to a limited extent. The axles of the clearer rollers are inserted into a mounting support, which is secured to the top of the upper roller support and weighting arm for displacement in the longitudinal direction thereof. The described mounting support of the upper rollers and clearer rollers requires a relatively large space.  
         [0006]     For textile technological reasons, it may be necessary to make an adaptation to the staple length of the fiber material, and to change to this end the distance between the nip lines formed by the paired rollers of the drafting system. This distance is also referred to as the nip spacing. Such a position change requires not only a manual adjustment or readjustment of the upper and lower rollers of the drafting system but also of all clearer rollers that interact with these readjusted rollers. The total labor requirements can be extensive in the case of the plurality of the spinning positions of a spinning machine that is equipped with conventional drafting systems, and lead to noticeable shutdown times of the spinning units.  
         [0007]     Based on the above-described state of the art, it is an object of the invention to improve the mounting support for upper rollers and clearer rollers in drafting systems of spinning machines.  
       SUMMARY OF THE INVENTION  
       [0008]     The above and other objects and advantages of the invention are achieved by the provision of a novel roller mounting assembly which is configured to mount the upper rolls of the drafting system in a mounting bracket so as to be above the lower driven rolls of the drafting system, and with the clearer rolls being mounted in the same mounting bracket so as to be above the upper rollers.  
         [0009]     The configuration of the mounting bracket in accordance with the invention provides a common mounting support for upper rollers and clearer rollers, which is stable and excellently suited for a cost-favorable series manufacture. The number of the components to be manufactured and assembled for the mounting support is reduced. In the case of a common mount of respectively interacting upper rollers and clearer rollers of the drafting system, only one adjustment step will be needed for changing the nip spacing. The clearer roller associated to the upper roller will move along, when it becomes necessary to change the distances between nips for a new spinning process by displacing the upper rollers. An additional adjustment of the position of the clearer rollers is not needed for adapting them to the new position of the upper rollers. It is thus possible to reduce the manual labor that is required for changing the distances between nips and the therewith connected shutdown time.  
         [0010]     When the mounting bracket comprises lateral side walls, which engage the upper roller support and weighting arm from the bottom on both sides, the upper side of the upper roller support and weighting arm remains free from components for mounting the clearer rollers. It is easily possible to provide there functional elements such as, for example, an operating lever. The clearer rollers are easy to insert into the lateral side walls. The mounting bracket requires little space. There remains adequate space in the interior of the upper roller support and weighting arm, for example, for tubular pressure elements, which are used to weight down the upper rollers.  
         [0011]     In an advantageous form of realization, one end of the clearer roller axle is constructed as a retaining device that comprises a collar. The retaining device engages behind a slotted guideway of the mounting element. Such a configuration permits arranging on each side of the upper roller support and weighting arm a clearer roller, whose axle is unilaterally supported. With that, it becomes possible to change a nip spacing on each individual upper roller support and weighting arm independently of adjacent upper roller support and weighting arms. In the case of such a configuration, it is not necessary to adapt the adjustment of facing bearings on respectively facing sides of adjacent upper roller support and weighting arms.  
         [0012]     An electrically conductive connection between the upper roller and the machine frame prevents the upper roller from being electrostatically charged. Such an electrostatic charge may lead to operational malfunctions and yarn imperfections.  
         [0013]     The mounting bracket of the invention offers the possibility of selecting its manufacture from sheet steel. A mounting bracket of sheet steel can be rapidly manufactured and in a cost-favorable manner by manufacturing steps such as cutting and bending, and it excellently withstands the stresses that are to be applied as a functional requirement. The mounting bracket when made from sheet steel has a relatively low weight and occupies little space.  
         [0014]     Guide flanges and guide slots make it possible to slide the mounting bracket with ease and continuously in the longitudinal direction of the upper roller support and weighting arm for the purposes of adjusting the rollers.  
         [0015]     When the axle of the upper rollers is held only by the elastic receptacle of a steering member, the upper roller may assume an undesired tilt. The tilt may reach an extent that adversely affects operation. If the lateral side walls of the mounting bracket comprise a slotted guideway, which forms in addition to the mount by the steering member element, a guidance for the axle of the upper rollers will be possible to prevent such a tilt from occurring. The mounting bracket permits constructing a steering member that mounts the axle of the upper rollers such that it has only a relatively small width and consists in a cost-favorable manner of an elastic plastic, without having to accept the above-described disadvantages. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     The invention is described in greater detail with reference to the drawings, in which:  
         [0017]      FIG. 1  is a simplified, perspective view of an upper roller support and weighting arm with an embodiment of a mounting bracket as well as upper rollers and clearer rollers;  
         [0018]      FIG. 2  is a perspective view of a base body of the mounting element of  FIG. 1 ;  
         [0019]      FIG. 3  is a simplified, perspective view of the upper roller support and weighting arm of  FIG. 1  with one clearer roller removed; and  
         [0020]      FIG. 4  is a simplified, perspective view of the upper roller support and weighting arm with the upper rollers and clearer rollers being partially sectioned. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     An upper roller support and weighting arm  1  is supported for pivoting about an axis  2  to an upper end position and a lower spinning operation position. A mounting support of this type for an upper roller support arm is disclosed, for example, in DE 44 29 671 C1. The upper roller support and weighting arm  1  is essentially U-shaped and open on its underside.  
         [0022]     Arranged on each side of the upper roller support and weighting arm  1  are an upper roller  3 ,  4  and a clearer roller  5 ,  6 . In the spinning operation position of the upper roller support and weighting arm  1 , the upper rollers  3 ,  4  are pressed against lower rollers not shown, as are disclosed, for example, in EP 0 344 944 A1.  
         [0023]     Both the upper rollers  3 ,  4 , which are mounted on an axle  37 , and the clearer rollers  5 ,  6  are held in a common mounting bracket  7 . The mounting bracket  7  is adjustable in the longitudinal direction of the upper roller support and weighting arm  1 , after releasing a locking device not shown, which can be operative in a force-locking or form-fitting manner. With that, it is possible to adjust the position of the mounting bracket  7 , when resetting the nip spacing. Additional upper rollers with associated clearer rollers may be arranged on the upper roller support and weighting arm in a simple manner by arranging on the upper roller support and weighting arm  1  and securing thereto additional mounting brackets  7 .  
         [0024]      FIG. 2  is a separate and enlarged view of a base body  27  of the mounting bracket  7  shown in  FIG. 1 . The base body  27  of the mounting bracket  7  is made symmetric and consists of steel. Its configuration is advantageously obtained by cutting blanks from sheet steel by means of punching or laser machining operations and by subsequent bending or edge turning operations, which suitably proceed in several steps. Two lateral side walls  8 ,  9  form with an intermediate guide member  10  the U-shaped base body  27  of the mounting bracket  7 , which laterally engages the upper roller support and weighting arm  1  from the bottom in the illustration of  FIG. 1 . The mounting bracket  7  is slipped over the free end of the upper roller support and weighting arm  1 , with guide flanges  11 ,  12  engaging guide slots  13 ,  14 ,  15  and providing on the upper roller support and weighting arm  1  a safe engagement and stable guidance of the mounting bracket  7 . The lateral side walls  8 ,  9  include slotted guideways  16 ,  17 , which each comprise parallel extending guide flanges  18 ,  19 ,  20 ,  21  for the clearer rollers. In the illustration of  FIG. 2 , the mounting bracket  7  occupies a position, in which the slotted guideways  16 ,  17  extend with their guide flanges  18 ,  19 ,  20 ,  21  in the vertical direction. This position corresponds to an inclination of the upper roller support and weighting arm  1  by 45°, which is indicated by line  24 . In this position, an axle  25  of the clearer roller  6  is able to slide easily up and down with a slight play.  
         [0025]     Unlike the illustration of  FIG. 1 , in the illustration of  FIG. 3 , the clearer roller  5  has been removed from its hollow bearing pin for providing an unobstructed view of the bearing. In the installed position of the clearer roller  5  on the hollow bearing pin, the clearer roller  5  is detachably secured to the hollow bearing pin by means of a stop or detent  26 . The stop or detent  26  interacts with a stop groove arranged in the interior of the clearer roller  5 , as is disclosed, for example, in DE 195 21 265 A1.  
         [0026]     The axle  25  of the clearer roller  5  is inserted into the slotted guideway  16  of the mounting element  7 .  FIG. 3  illustrates the position, which the clearer roller  6  assumes, when it lies under its own weight against the upper roller  3  during the spinning operation. When the upper roller support and weighting arm  1  is pivoted to its upper end position, and, in so doing, raises the clearer rollers  5 ,  6  from the upper rollers  3 ,  4 , the clearer rollers  5 ,  6  are no longer supported by the upper rollers  3 ,  4 , and the axles of the clearer rollers  5 ,  6  slide in the slotted guideways  16 ,  17  downward, until they come to lie against support ledges  22 ,  23 .  
         [0027]     The axle  25  is constructed as a hollow bearing pin. At its end inserted into the slotted guideway  16  of the mounting element  7 , the hollow bearing pin comprises a collar  29 , which engages behind the lateral side wall  8  and causes the clearer roller  5  to be unilaterally retained in the mounting bracket  7  during the spinning operation. The base body  27  of the mounting bracket  7  includes on each side a recess  28  and  30  respectively, which are constructed as slotted guideways, and serve to guide the axle  37  of the upper rollers  3 ,  4 . The guidance by the recesses  28 ,  30  becomes operative upon insertion of the axle  37  into the mounting bracket  7 .  
         [0028]      FIG. 4  is a sectional view of the upper roller support and weighting arm  1  in the direction of its free end. The sectional plane extends through the axes of rotation of the upper rollers  3 ,  4  and clearer rollers  31 ,  32 . Unlike the embodiment shown in  FIGS. 1 and 3 ,  FIG. 4  illustrates alternative embodiments of the mounting bracket and the clearer rollers. Slipped onto the upper roller support and weighting arm  1  is a mounting bracket  7 A, which comprises a base body  27 A and a steering member  36 . In this embodiment, the guide flanges  11 ,  12  of the upper roller support and weighting arm  1  engage guide slots of a guide member  10 A of mounting bracket  7 A. Inserted into both sides of the upper roller support and weighting arm  1  are clearer rollers  31 ,  32 . With the end of their axles  33 ,  34 , the clearer rollers  31 ,  32  are able to slide up and down in slotted guideways. Since the section in the illustration of  FIG. 4  extends through the slotted guideways, the Figure shows only the guide flanges  19 A and  21 A of the slotted guideways, which are each oriented toward the free end of the upper roller support and weighting arm  1 . With the other end of their axles  33 ,  34 , the clearer rollers  31 ,  32  are inserted into a mounting support not shown for reasons of simplification, which is arranged on each adjacent upper roller support and weighting arm. With that, each clearer roller  31 ,  32  extends over respectively two yarn tracks.  
         [0029]     The clearer rollers  31 ,  32  lie under their own weight against the upper rollers  3 ,  4 . To secure the upper rollers  3 ,  4  to the upper roller support and weighting arm  1 , their axle  37  is manually inserted from the bottom into an elastic receptacle  35  of the steering member  36 . In a likewise simple manner, the axle  37  can again be removed from the receptacle  35 . The steering member  36  consists of plastic and includes a pressure plate  38  at its upper end. The pressure plate  38  is biased by a pressure load from a tubular pressure member  39 , in that the latter receives in a customary manner compressed air from a source of compressed air that is not shown for the sake of simplicity. The steering member  36  of the mounting bracket  7 A is adapted for vertical upward and downward movement, so that the weight is transmitted to the upper rollers  3 ,  4 . In this manner, the upper rollers  3 ,  4  are pressed against lower rollers in their position during the spinning operation. A spinning operation position, in which the upper rollers are arranged in a mounting support and pressed against the lower rollers, is disclosed, for example, in EP 0 344 944 A1.  
         [0030]     The base body  27 A of the mounting bracket  7 A comprises lateral side walls  8 A,  9 A, of which a sectional view is shown in  FIG. 4 . These lateral side walls  8 A,  9 A comprise recesses  28 A,  30 A, whose width is adapted to the corresponding diameter of the axle  37  of upper rollers  3 ,  4 , and in which the axle  37  extends sideways. The recesses  28 A,  30 A of the base body  27 A are constructed as slotted guideways in the same way as the recesses  28 ,  30  of the base body  27 . This guideway prevents a disadvantageous tilt of the upper rollers  3 ,  4  relative to the drafting direction. Such a tilt can occur, when the axle  37  is guided only by the elastic receptacle  35  of the steering member  36 .  
         [0031]     The invention is not limited to the described embodiments. Clearer rollers as are disclosed, for example, in DE 195 21 265 A1, may be supported with their pivot arm not directly on the upper roller support and weighting arm as disclosed in DE 195 21 265 A1, but on an adjustable, common mounting element for the respectively associated upper rollers and clearer rollers, and thus represent an alternative embodiment within the scope of the invention