Abstract:
A textile machine, especially a spinning preparation machine, included a drafting device having several drive disks for driving machine elements, especially drafting device rollers. At least one endless belt surrounds at least two of the drive disks. The belt comprises at least two longitudinal ribs on one side that are received in corresponding longitudinal grooves on the circumference side and running in the circumferential direction of at least one drive disk in contact with the endless belt.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to a textile machine, especially a spinning preparation machine with a drafting device. The drafting device has several drive disks for driving machine elements, especially drafting device rollers, and has at least one endless belt surrounding at least two drive disks.  
       BACKGROUND OF THE INVENTION  
       [0002]     Textile machines that employ drafting devices are widely known. Three roller pairs are provided in drafting frame RSB-D 35 of the Rieter company that have a circumferential speed that increases from the entrance of the drafting device to the exit of the drafting device. The particular lower roller of the drafting device rollers is driven by flat belts for producing a drive that is as slippage-free as possible to provide for an orderly drafting of the slivers [slubbing]. The upper rollers are pressed against the lower rollers, thus clamping the yarn [fiber] material running through between them.  
         [0003]     It turned out that flat belts have many advantages over the earlier toothed-type belts still frequently used at times but that an undesired elongation slippage can result due to the relatively high elasticity of the flat belt. This springiness of the flat belt occurs in particular during a dynamic change of speed so that errors result in the transfer behavior. In addition, a re-adjustment must be performed in the case of an irreversible elongation and the sliding slippage produced as a consequence thereof. In contrast thereto, toothed-type belts, that, in addition, are relatively easy to manipulate, have less of a tendency to slip but have the disadvantage that that they run unevenly when contaminated. In addition, toothed-type belts exhibit the so-called polygon effect in which knocks occur due to the teeth folding into the gaps between the teeth. One other disadvantage is the fact that no continuous translation change is possible with toothed-type belts.  
       SUMMARY OF THE INVENTION  
       [0004]     It is therefore a principal purpose of the present invention to create an improved drive for drive disks in a textile machine. Additional advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.  
         [0005]     This principal purpose is solved for a textile machine by a belt comprising at least two longitudinal ribs on one side that are received in corresponding longitudinal grooves of at least one drive disk that are on the circumferential side and run in the circumferential direction.  
         [0006]     Several advantages result from using a belt longitudinally profiled with ribs and grooves in accordance with the invention. One advantage is the fact that the belt is guided more precisely in the longitudinal direction in comparison to a flat belt due to its rib-and-groove structure. A centered belt course is always guaranteed by means of the at least two longitudinal ribs. Therefore, the use of such a belt is also possible in the case of not absolutely parallel shafts [axes]. In addition, no periodic errors occur in the case of contamination in comparison to a toothed-type belt with its transverse grooves. Also, no polygon effect disturbs the even running, as is the case for toothed-type belts. Therefore, greater dynamics with better transfer properties can also be achieved with the belts exhibiting the longitudinal rib-and-groove structure.  
         [0007]     On the whole, a very even, almost oscillation-free running can be achieved in contrast to toothed-type belts. Moreover, the stiffness of such a belt and its modulus of elasticity are greater than in a flat belt, so that a more precise transfer behavior results, especially in the case of dynamic changes of speed. Thus, a more favorable dynamic behavior can be achieved at such changes of speed with the belt in accordance with the invention.  
         [0008]     Furthermore, a continuous translation change is possible when using the cited belt in accordance with the invention, which is a serious disadvantage with toothed-type belts in particular.  
         [0009]     Also, greater translation conditions [ratios] and greater belt speeds can be achieved with the drive of the invention compared to the previously used belts, e.g., belt speeds of 60 m/s. Since the contact surface is greater due to the longitudinal profiling compared to a flat belt with the same belt width, on the whole greater performances [power] can be transferred. In this manner, very high speeds of the drive disks and therewith in particular of the drafting device rollers can be achieved so that sliver delivery speeds of distinctly more than 1000 m/min with a high degree of precision of the drafted sliver are possible.  
         [0010]     Another advantage over traditional toothed-type belts is the fact that the use of belts with rib-and-groove structure in accordance with the invention makes possible crossed or bent belt drives in which the axes of two looped drive disks do not run parallel to or at 90° to one another. This significantly increases the structural play during the construction of the machine.  
         [0011]     Further, the circumferentially running grooves of the drive disks can be produced relatively simply by turning using a shaping chisel with any desired diameter. Turning has the additional advantage that no graduation with a fixed number of teeth (as in the case of a toothed-type belt) is necessary. The forming of running grooves of the drive disks is simpler and easier as compared to creating recesses in the drive disk use with tooth-type belt, whereby, the recesses of the drive disks for toothed-type belts must be laboriously milled or tapped.  
         [0012]     The ribbed belt comprises in an especially preferred manner more than two longitudinal ribs running parallel to each other. The plurality of ribs with longitudinal grooves arranged between them assure on the one hand a uniform distribution of force over the entire belt width and on the other hand guarantee an especially good frictional connection.  
         [0013]     The at least two longitudinal ribs can be designed in a wedge shape [V-shape] in an advantageous embodiment. This results in a wedge-rib [V-ribbed] belt known from other areas of application that has an extremely high flexibility so that great translation ratios can be achieved even with very small drive disks (e.g., 1:40). Also, great counterflections can be achieved with such a belt so that a versatile use with a low space requirement is possible.  
         [0014]     The side of the belt opposite the ribs and grooves can be designed in various manners. In one variant, this opposite side is designed to be flat, so that during the deflection of the belt this flat side runs on a drive disk. This drive disk can have either the cited rib-and-groove profiling in the longitudinal direction or a smooth surface or even a toothed profile.  
         [0015]     Alternatively, for example, the belt may also have a profile on its side facing away from the longitudinal ribs, which has at least two longitudinal ribs, or the belt may have a profile with transverse ribs, that is, a tooth profile. In the first-cited instance of a double profiling with longitudinal ribs, the front and the back side of the belt can be used in accordance with the invention, which is especially advantageous given differences in the direction of rotation of two shafts.  
         [0016]     A cleaning effect of the belt can be achieved in the case of a profiling on only one side as well as one on both sides by deflection on both sides, a suitable looping angle and by a differing flexion, so that the dirt can fall out of the grooves and does not settle on the surfaces of the drive disks.  
         [0017]     Cleaning devices, e.g., permanently arranged brushing-off devices or nozzles with a blowing pulse can be used to clean the belt grooves and/or the drive disks.  
         [0018]     Several driven disks can be simultaneously driven with particular preference by a drive disk through the means of the rib belt or wedge-rib belt. This possibility results from the fact that greater performances can be transferred in comparison to flat belts. Thus, one drive shaft and several driven shafts can be arranged on one belt line. The intermediate shafts required in the state of the art can be eliminated. The number of belts and, in particular, the number of shafts and supports can thus be reduced in comparison to the known, comparable textile machines, which can lower expenses. Also, on the whole smaller masses to be driven result, so that the massive inertias are also smaller and therefore greater machine dynamics can be achieved. In addition, only the one belt needs to be slackened if several change gears are to be replaced on this belt line, e.g., for adjusting a different sliver fineness of the drafted material or for adapting the machine to different textile materials. Previously, in order to replace any change gear the associated belt had to be slackened.  
         [0019]     In another aspect of the invention, the textile machine includes a device by means of which the at least one belt can be adjusted independently of its length and the diameter of the at least one looped drive disk to a belt tension that is substantially the same in all instances. In the traditional toothed-type belt drives, the belt tension is adjusted by the operator according to his own judgment or with the aid of an appropriate measuring device to a value that is fixed at first. In the case of known flat belts, their theoretical tension can be fixed with the aid of a clamping screw arranged on a tensioning lever. A tensioning or deflection roller for the flat belt is arranged on the spring-loaded tensioning lever. Thus, even the tensioning roller is held in its place by fixing the clamping screw. If the flat belt or the previously cited toothed-type belt expands in a non-elastic manner, the belt tension is reduced; so that it must be readjusted by the user. A different spring may have to be used during a replacement of the drive disk by a drive disk with a different circumference.  
         [0020]     In contrast thereto, in the cited aspect of the invention, the belt tension adjusts itself to a value that is substantially the same in all instances without the user actively adjusting the belt tension by using force or the like, so the expense for maintenance and replacement is reduced. The belt tension can adjust itself in this instance to the predetermined value independently of the size of the drive disk or the length of the belt used. Measurement of the belt tension and an unclear reliance on values gained from experience are no longer necessary.  
         [0021]     To this end, the device comprises in an especially preferably manner at least one movably mounted tensioning roller or deflection roller for belt tensioning that is force-loaded and thus correspondingly tensions the belt to the predetermined force without the user having to intervene. To this end, the tensioning roller is mounted, e.g., in a linearly guided carriage on which the force is to be applied by the device. In this manner, a predetermined belt tension can be realized even with different change gear diameters or when adjusting different roller settings. The belt tension adjusts itself in the case of different diameters of change drive disks or the case of belts with different lengths by shifting the tensioning roller to a constant value when the looping angle (engagement angle) of the belt around the tensioning roller is approximately 180° according to a preferred embodiment. If this angle number is deviated from, the belt tension for change gears with a different diameter assumes different values. However, these different values can be in the tolerated range, depending on the area of application. Thus, it is possible that looping angle is in a range between approximately 170° and 190° or also in a range between 160° and 200°.  
         [0022]     The cited tensioning roller is preferably loaded directly or indirectly with a spring force that is preferably applied by a gas spring. A gas spring has the particular advantage that the force-path characteristic curve runs approximately horizontally, so that, in the case of the cited looping angle of approximately 180°, a constant belt tension can be adjusted even given different deflections of the tensioning roller due to, e.g., belt expansion or after a replacement of drive disks with different diameters.  
         [0023]     In addition, if the gas spring is advantageously provided with a damping, oscillations of the at least one belt during the operation of the machine can be largely prevented.  
         [0024]     In an alternative advantageous embodiment, the tensioning roller can be fixed in its position by a fixing device in order to avoid oscillations during operation here too. The fixing device, e.g., a clamping screw, can act on the above-cited carriage to this end in accordance with the embodiment, thereby fixing it in its position. Loosening the fixing device brings the belt to the predetermined tension on account of the loading of force that is then active, so that subsequently only the fixing device must be reactivated. The operator, therefore, does not have to re-tension the belt himself. During a replacement of one drive disk by a drive disk with a different diameter, the looping of the tensioning roller with a looping angle of approximately 180° thus makes possible a rapid and automatic belt tensioning up to the loosening and re-fixing of the fixing device.  
         [0025]     Alternatively, the belt tension can also be constantly tensioned continuously, that is, without a fixing in place of the tensioning roller, during the operation of the machine. An example of such a constant and continuous tensioning is the above-cited gas spring with damping. A constant compensation of the longitudinal tolerance of the belt is achieved therewith. Also, the service life of the belt is increased by the continuous adjusting of the optimum tension. Thus, in this embodiment, no fixing device is necessary.  
         [0026]     Advantageous further developments of the invention are described further in the following description.  
         [0027]     The invention is explained in detail in the following with reference made to the figures.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]      FIG. 1  shows a transmission plan of a drafting frame;  
         [0029]      FIG. 2  shows a drive disk with a wedge-rib belt in a sectional view;  
         [0030]      FIG. 3  shows a bent section of a wedge-rib belt in a cross-sectional view;  
         [0031]      FIG. 4  shows a belt with a wedge-rib profile on both running-surface sides in a cross-sectional view;  
         [0032]      FIG. 5  shows a belt with a wedge-rib profile on the one running-surface side and with a toothed profile on the other running-surface side in a cross-sectional view; and  
         [0033]      FIG. 6  shows a schematic view of a device for belt tensioning. 
     
    
     DETAILED DESCRIPTION  
       [0034]     Reference will now be made in detail to the presently preferred embodiments of the invention, one or more examples of which are shown in the figures. Each example is provided to explain the invention, and not as a limitation of the invention. In fact, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a further embodiment. It is intended that the present invention cover such modifications and variations.  
         [0035]     A transmission plan of a drafting frame with drafting device  2  is shown in  FIG. 1 . The various elements of drafting frame  1  are driven by two motors  3 ,  40 . The first motor  3  is provided for driving elements in front of drafting device  2  as well as for driving two front drafting device rollers, whereas the second motor  40  drives the last drafting device roller as well as elements located after drafting device  2 . In order to transfer power from the drive disks onto the driven disks, the invention provides that belts with at least two longitudinal ribs on one running side are at least partially provided.  
         [0036]     The transmission plan of  FIG. 1  is explained in detail in the following. The first motor  3  drives drive disk  6  via drive shaft  5 . This drive disk  6  exhibits a rib-and-groove structure in a circumferential direction (see  FIG. 2 ). Wedge-rib belt  7  is tensioned via drive disk  6  and drives four driven disks  8 ,  14 ,  16 ,  21  located in front of drafting device  2 . For its part, driven disk  16  drives driven disk  17  via a shaft which disk  17  causes driven disk  19  to rotate via belt  18 . This driven disk  19  drives transport rollers  20  arranged on both sides of it for drawing slivers out of feed cans (not shown). Only the drawing of two slivers from the cans closest to drafting device  2  is shown here; normally, six or eight slivers are drawn off from a corresponding number of feed cans set up in series and in pairs. The two driven disks  14  drive two transport rollers  15  running in the same direction (on which a jockey roller rolls in a known manner), which transport the slivers that have been brought together in the meantime to drafting device  2 .  
         [0037]     The following driven disk  8  drives deflection drive  9  and the correspondingly deflected belt  10  drives the two disks, running in opposite directions, of a known groove-sensing roller pair with the aid of drive disk  12  and belt  11 . With the aid of groove sensing roller pair, the fluctuations in the sliver cross section are determined for being leveled out in drafting device  2 .  
         [0038]     The last driven disk  21  driven by belt  7  is connected via shaft  22  to two driven disks  23 ,  26 . The device disk  23  drives lower entrance roller  30  with the aid of belt  24  and another driven disk  25 . The driven disk  26  drives lower middle roller  31  with the aid of another belt  27  and another driven disk  29 . The particular upper rollers (not shown) are cause to rotate by being pressed against lower rollers  30 ,  31 .  
         [0039]     The second motor  40  is connected via drive shaft  41  to two drive disks  42 ,  51 . Driven disk  42  causes two calander rollers to rotate in opposite directions via belt  43  on the one hand with driven disk  44  for driving lower exit roller  32  and on the other hand with driven disk  45  and with the aid of a known transmission [changeover]  46  (driven here with a toothed belt). The sliver (shown in dotted lines) given off from the exit roller pair with running direction A is transported by calander rollers  48  into sliver conduit  49  arranged in rotary plate  50  and deposited from the latter into rotating can  59 . Calander rollers  48  as well as the can stock together with can  59  are shown tilted in the transmission plan of  FIG. 1  by 90° relative to the drafting device.  
         [0040]     Finally, rotary plate  50  is driven via the other drive disk  51  connected to shaft  41 . To this end, belt  52  is looped around drive disk  51 , which belt drives driven shaft  53  and driven disk  54  coupled to it. Driven disk  54  is permanently connected to driven disk  55  that drives the rotary plate via belt  56 . Can plate  58  is driven via driven disk  54  by means of drive  57  in order to selectively cause can  59  to rotate during the filling process.  
         [0041]      FIG. 2  shows cut drive disk  70  in a sectional view. Drive disk  70  includes ribs  71  and grooves  72  running on its circumferential surface in the circumferential direction. Belt ribs  81  of wedge-rib belt  80  engage into disk grooves  72  whereas disk ribs  71  engage into belt grooves  82 . An intermediate space is present between the particular ribs and grooves so that the ribs and grooves contact each other substantially non-positively on their steep flanks.  
         [0042]      FIG. 3  shows a section of wedge-rib belt  80  in a slightly curved form . It is particularly apparent that ribs  81  start from belt back  83 . The running surface  85  facing away from the rib structure is designed in a plane surface. The flat running side  85  can not only drive a drive disk with a smooth circumferential surface, but also, e.g., the flat running side  85  can drive a drive disk having a rib-groove structure in the circumferential direction like drive disk  70 .  
         [0043]     A few or all belts  7 ,  18 ,  24 ,  27 ,  43 ,  52  in accordance with  FIG. 1  can be designed as wedge-rib belts. The correspondingly looped drive disks preferably also have a corresponding rib-groove profiling in the longitudinal direction.  
         [0044]      FIG. 4  shows another embodiment of a belt  180  with longitudinal rib structure  86 ,  87  on two sides of the running surface. Both sides of this belt  180  can therefore be used for an optimal driving of appropriately designed drive disks and/or driven disks with ribs and grooves in the circumferential direction.  
         [0045]     Belt  280  in accordance with  FIG. 5  comprises longitudinal rib-groove structure  86  on one side of the running surface and toothed profile  89  on the other side of the running surface. In this manner, the belt  280  can be used in machines comprising both drive disks with ribs and grooves running in the circumferential direction as well as drive disks with a toothed profile.  
         [0046]      FIG. 6  shows wedge-rib belt  80  [looped around drive disk  70  and driven disk  75   a  and  75   b . A special tensioning device  93  is provided for tensioning belt  80 . Belt  80  is guided by deflection disk  90  and loops around tensioning roller  95  at a looping angle α of approximately 180°. Furthermore, tensioning roller  95  is connected to tensioning lever  96  supported around rotary shaft  98 . The direction of pivoting of tensioning lever  96  is designated with f 2 . Tensioning lever  96  is loaded by a spring, such as gas spring  99  with stamp  99   a . A constant force is applied in direction f 1  on the tensioning lever  96  by the stamp  99   a  of gas spring  99 , so that tensioning roller  95 , that is linearly guided (see arrow f 3 ) in carriage  94 , is loaded with a constant force. In this manner, an always constant tension of wedge-rib belt  80  results due to the 180° looping and the use of gas spring  99 . Even in the instance of an irreversible expansion of belt  80 , it is constantly held at the predetermined tension by gas spring  99 .  
         [0047]     In order to avoid any oscillations during operation, carriage  94  (or also tensioning lever  96 ) can be clamped fast by clamping screw  97  or some other fixing device so that tensioning roller  95  is power-loaded except to monitor the tensioning force or for a subsequent tensioning by gas spring  99 . To this end, clamping screw  97  is loosened so that the belt tension can automatically readjust itself, and subsequently clamping screw  97  is retightened.  
         [0048]     If one of driven disks  75   a ,  75   b  is replaced by the other one, at first the belt tension is reduced by pivoting the tensioning lever  96 . If clamping screw  97  is used, it is also loosened. After having pivoted the tensioning lever  96  back, the same belt tension is then automatically adjusted for the new driven disk  75   a  or  75   b  by virtue of the power-loading by gas spring  99  as for the replaced drive disk  75   b  and  75   a . The clamping screw can subsequently be retightened. Any other manual intervention by the user is unnecessary.  
         [0049]     In another, even simpler embodiment clamping screw  97  is not present. Instead, gas spring  99  is designed to be damped in order to avoid oscillations of belt  80  during operation. The construction is otherwise the same as the one shown in  FIG. 4 .  
         [0050]     Looping angle α of 180° does not have to be absolutely maintained if a certain error can be accepted without this resulting in a noticeable or significant loss of quality in the resulting sliver. The belt tension is different at an angle α deviating from 180° when using driven disk  75   a  than that when using driven disk  75   b . Looping angle α can be, e.g., between approximately 160° and 200°. For example, in some practical examples, a looping angle of 170° still shows good results.  
         [0051]     The present invention is not limited to the exemplary embodiments shown and described. Modifications within the scope of the patent claims are readily possible. Thus, even other longitudinal rib profiles than the wedge ribs shown can be used. It will be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention.