Abstract:
An apparatus and a method for spinning and depositing a tow ( 15 ). To this end, one or more fiber bundles ( 7 ) are melt spun by means of a spinning device ( 1 ), and withdrawn as a tow by a withdrawal system ( 2 ). Subsequently, the tow ( 15 ) is laid by means of a depositing device ( 3 ) into a can ( 4 ). To be able to apply the necessary withdrawal forces to the tow ( 15 ), the tow ( 15 ) advances along an S-shaped guide path by partially looping the rolls ( 9, 10 ) of the withdrawal system ( 2 ). To be able to change the degree of the looping on the rolls, in particular for piecing and threading the tow ( 15 ), some of the rolls ( 10 ) of the withdrawal system ( 2 ) are mounted for displacement on the machine frame in such a manner that they permit changing the guide path of the tow ( 15 ).

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     The present application is a continuation of international application PCT/DE03/05170, filed 16 May, 2003, and which designates the U.S. The disclosure of the referenced application is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The invention relates to an apparatus and method for spinning and depositing a tow of the general type disclosed in EP 0 875 477 A2.  
         [0003]     In the production of staple fibers, it is known to spin an individual tow from a polymer melt in a first processing step, and to deposit it into a can. In a second processing step, a plurality of individual tows are withdrawn from the respective cans and combined to a common tow and cut to staple fibers by means of a fiber cutter. The apparatus which is used exclusively for carrying out the first process step, forms the basis of the present invention.  
         [0004]     For spinning and depositing a tow, the known apparatus comprises a spinning device for spinning a plurality of fiber bundles, a withdrawal system with a plurality of rolls for withdrawing the tows formed by the fiber bundles, and a depositing device for laying the tow into a can. To apply the necessary withdrawal forces, the withdrawal system comprises a plurality of rolls, one following the other in offset relationship, so that the tow advances through the withdrawal system along an S-shaped path by partially looping the rolls. In so doing, the tow advances over the intermediate rolls with a partial looping of preferably at most 180°. These deflections are needed on the one hand for producing high withdrawal forces. On the other hand, they lead to significant problems with threading the tow at the beginning of the process. In this connection, the tow must be manually inserted into the predefined S-shaped guide path, which requires applying accordingly great manual forces in particular in the case of relatively thick tows.  
         [0005]     It is therefore an object of the invention to further develop an apparatus as well as a method of the initially described type in such a manner that the tow can be pieced and threaded at the beginning of the process by a more simple handling procedure.  
         [0006]     It is a further object of the invention to make the withdrawal of the tow from the spinning device as flexible as possible.  
       SUMMARY OF THE INVENTION  
       [0007]     The above and other objects and advantages of the invention are provided by a spinning apparatus and method of the described type and wherein at least one of the rolls of the withdrawal system is supported form movement on the machine frame in such a manner to permit changing of the guide path of the tow between the rolls. Thus the degree of looping between the tow and the rolls of the withdrawal system can be varied and adjusted. With that, it is possible to adjust to configurations with a high degree of looping for building up high withdrawal forces, or to configurations with a small degree of looping for building up correspondingly low withdrawal forces, or for threading and piecing the tow.  
         [0008]     The range of adjustment of the looping angles is preferably from 0° to 180° on the intermediate rolls of the withdrawal system. To this end, at least some of the rolls in the withdrawal system are mounted for displacement to the machine frame in such a manner that they permit changing the guide path of the tow. The movability of the rolls in the withdrawal system serves only for adjusting a defined guide path of the tow or a defined looping angle. During the spinning and depositing of the tow, the movable rolls are secured in their respective positions on the machine frame, so that no undesired change of the guide path or the looping angle can occur.  
         [0009]     A particularly advantageous further development of the invention provides for making the movable rolls adjustable between a threading position and an operating position. In this case, the tow advances in the threading position substantially without partial looping along a straight path between the rolls of the withdrawal system. Only after the movable rolls have been adjusted and secured in their operating position, will the tow advance with a corresponding partial looping over the rolls along an S-shaped path for applying the withdrawal forces.  
         [0010]     To be able to thread the tow during the piecing step in a simplest possible manner, a spacing is formed between the stationary rolls and the movable rolls in the threading position, so that the tow can be inserted into the withdrawal system with no significant contact.  
         [0011]     After the insertion of the tow into the withdrawal system, the rolls that are mounted for displacement to the machine frame are moved from their threading position to their respective operating position. To this end, the movable rolls can be adjusted synchronously, namely at the same time. With that, it is possible to obtain short times for piecing and threading the tow.  
         [0012]     However, it is also possible to bring the movable rolls sequentially, i.e., one after the other, from their threading positions to their operating positions. With that, the withdrawal tension in the tow is prevented from rising suddenly, and is instead allowed to build up in the tow slowly.  
         [0013]     The apparatus and method for the invention further includes a depositing device for laying the withdrawn tow into a can. The depositing device preferably comprises two cooperating conveying rolls, of which at least one of the conveying rolls is made movable for displacement between an operating position and a threading position. This is especially suited for automating the threading and piecing steps of the tow. In this connection, a spacing between the conveying rolls is formed in the threading position of the conveying rolls, which facilitates the insertion of the tow.  
         [0014]     Advantageously, the withdrawal system and the depositing device are successively arranged such that in the threading position of the movable rolls of the withdrawal system and in the threading position of the movable conveying roll of the depositing device, it is possible to insert the tow into a common, straight line guide path.  
         [0015]     In an arrangement wherein the spinning device, the withdrawal system, and the depositing device are arranged in tiers one on top of the other, it is easy to advance the tow from the spinning device automatically through the withdrawal system and the depositing device into an available can. As soon as the piecing and threading steps of the tow are completed, both the movable rolls and the movable conveying roll are moved to their respective operating position, and production can start.  
         [0016]     The apparatus and the method of the invention are suited in particular for spinning and depositing thick tows with coarse deniers of the fiber bundles of, for example, &gt;12,000 dtex. The spinning device may comprise a plurality of spinnerets arranged in parallel side-by-side relationship for producing a plurality of fiber bundles, or one spinneret with, for example, at least 8,000 spin holes. Spinnerets of this type allow realizing high melt throughputs of more than 500 kg/h, which result in a correspondingly thick tow. Thus, the apparatus of the invention is also suited for being combined with a plurality thereof to form a complete production line. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     In the following, several embodiments of the apparatus according to the invention and the method of the invention are described in greater detail, with reference to the attached drawings, in which:  
         [0018]      FIG. 1 . 1  and are schematic views of a first embodiment of the apparatus according to the invention; and  
         [0019]      FIG. 2  is a schematic view of a further embodiment of the apparatus according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]      FIG. 1 . 1  shows the apparatus during the piecing and threading steps of the tow, and  FIG. 1 . 2  shows the apparatus in operation during the production of the tow. The following description will apply to both Figures, unless express reference is made to one of the Figures.  
         [0021]     The apparatus comprises a spinning device  1 , a withdrawal system  2  extending downstream of the spinning device  1 , a subsequent depositing device  3 , and a can  4  arranged downstream of the depositing device  3 . The can  4  is supported on a can traversing device  5 .  
         [0022]     The spinning device comprises two spinnerets  6 . 1  and  6 . 2 , which are arranged in a parallel, side-by-side relationship. Each of the spinnerets  6 . 1  and  6 . 2  connects via a melt supply line  17 . 1  and  17 . 2  to a melt source (not shown). On their underside, the spinnerets  6 . 1  and  6 . 2  comprise a plurality of spin holes, from each of which a fiber is extruded. The spinnerets  6 . 1  and  6 . 2  may comprise more than 80,000 spin holes. Thus, each of the spinnerets  6 . 1  and  6 . 2  extrudes a fiber bundle  7 . 1  and  7 . 2 . Downstream of the spinnerets, the spinning device  1  normally comprises cooling devices, which generate a cooling air stream for cooling the fiber bundles. In the present embodiment, the cooling device has been omitted. Likewise the number of the spinnerets of spinning device  1  is exemplary. Thus, three, four, five, or even more spinnerets may be arranged in a parallel, side-by-side relationship, with their fiber bundles being each combined to a tow.  
         [0023]     To combine the fiber bundles  7 . 1  and  7 . 2  to a tow  15 , a plurality of fiber lubrication elements  8 . 1 - 8 . 4  are arranged between the spinning device  1  and the withdrawal system  2 . During the process, the fiber lubrication elements  8 . 1 - 8 . 4  apply a lubricant to the fiber bundles  7 . 1  and  7 . 2  or the tow  15 . In the present embodiment, the fiber lubrication elements  8 . 1 - 8 . 4  are lubrication rolls. However, it is also possible use lubrication pins.  
         [0024]     Arranged downstream of the lubrication rolls  8 . 1 - 8 . 4  is the withdrawal system  2 . The withdrawal system  2  comprises a plurality of rolls  9 . 1 - 9 . 3  that extend one after the other in a vertical plane. The rolls  9 . 1 - 9 . 3  are rigidly mounted to a machine frame  12 . Between the rolls  9 . 1  and  9 . 2 , the machine frame  12  includes a linear guideway  11 . 1 , in which a roll  10 . 1  is arranged for displacement. Between the rolls  9 . 2  and  9 . 3 , the machine frame likewise includes a linear guideway  11 . 2 , in which a roll  10 . 2  is arranged for displacement. In their respective linear guideways  11 . 1  and  11 . 2 , the rolls  10 . 1  and  10 . 2  can be moved between a threading position and an operating position. In this process, the rolls  10 . 1  and  10 . 2  are moved transversely to the direction of the advancing tow  15 .  
         [0025]      FIG. 1 . 1  illustrates the situation, in which the movable rolls  10 . 1  and  10 . 2  of the withdrawal system  2  are held in a threading position on the machine frame  12 . To this end, the movable rolls  10 . 1  and  10 . 2  are displaced in their respective linear guideways  11 . 1  and  11 . 2  to the right side of the machine frame, so that the tow  15  advances along a straight path without partially looping the rolls  10 . 1  and  10 . 2 . Between the stationary rolls  9 . 1 ,  9 . 2 , and  9 . 3  and the movable rolls  10 . 1  and  10 . 2 , a spacing is formed, so that the tow  15  is able to advance substantially without contact in the center of the withdrawal system  2  between the stationary rolls  9 . 1 - 9 . 3  and the movable rolls  10 . 1 - 10 . 2 . This arrangement is especially advantageous for inserting the tow  15  after piecing in a simple manner into the withdrawal system  2 .  
         [0026]     After the tow  15  has been inserted into the withdrawal system  2 , the movable rolls  10 . 1  and  10 . 2  are displaced to the left in the linear guideways  11 . 1  and  11 . 2  on the machine frame  12 , so that the movable rolls  10 . 1  and  10 . 2  extend through the vertical plane of the stationary rolls  9 . 1 - 9 . 3 , and form an S-shaped guide path which is needed for withdrawing the tow  15 . This situation is shown in  FIG. 1 . 2 . The stationary rolls  9 . 1 - 9 . 2  and the movable rolls  10 . 1  and  10 . 2  are arranged one after the other in offset relationship, so that the tow  15  passes each of the roll with a predetermined partial looping. In this situation, the movable rolls  10 . 1  and  10 . 2  are locked in position on the machine frame  12 .  
         [0027]     For advancing the tow  15 , the rolls  9 . 1 - 9 . 3  as well as the rolls  10 . 1  and  10 . 2  are driven. In this connection, it is preferred to drive each of the rolls by a separate drive unit. However, it is also possible to drive groups of rolls by a group drive unit.  
         [0028]     Downstream of the withdrawal system  2  is the depositing device  3 . The depositing device  3  is formed by two cooperating conveying rolls  13 . 1  and  13 . 2 . The conveying rolls  13 . 1  and  13 . 2  are driven at the same speed, so that the tow  15  uniformly advances into the can  4  that is placed below the depositing device  3 .  
         [0029]     The can  4  may be moved by a traversing device  5  such that when depositing the tow  15 , the can  4  is evenly filled.  
         [0030]      FIG. 2  illustrates a further embodiment of the apparatus according to the invention. The construction of the apparatus shown in  FIG. 2  is largely identical with that of the foregoing embodiment of  FIG. 1 , so that the foregoing description is herewith incorporated by reference, and that only differences will be described in greater detail.  
         [0031]     In the embodiment shown in  FIG. 2 , the spinning device  1  comprises only one spinneret  6  for producing a fiber bundle  7 . The fiber bundle  7  is combined via fiber lubrication elements  8 . 1 - 8 . 4  to the tow  15 .  
         [0032]     The withdrawal system  2  is made identical with the foregoing embodiment. The present embodiment shows the situation, in which the movable rolls  10 . 1  and  10 . 2  are held in the threading position.  
         [0033]     Downstream of the withdrawal system is the depositing device  3 . The depositing device  3  of the present embodiment is formed by a stationary conveying roll  13  and a movable conveying roll  14 . The movable conveying roll  14  is mounted in a guideway  18 , which permits displacing the movable conveying roll  14  between an operating position and a threading position.  FIG. 2  shows the situation, in which the movable conveying roll  14  remains in the threading position. In this position, a spacing exists between the conveying rolls  13  and  14 , so as to permit inserting the tow  15  along a straight guide path from the spinning device  1  as far as the can  4 . This embodiment of the apparatus according to the invention is therefore especially suited for permitting an automatic piecing and threading of the tow  15 . In this instance, an operator needs to monitor only the piecing of the fiber bundle. The threading of the tow  15  into the withdrawal system  2  and depositing device  3  can occur automatically by falling into place.  
         [0034]     As soon as the tow  15  advancing from the spinning device  1  enters the can  4 , the movable rolls  10 . 1  and  10 . 2  of the withdrawal system  2  and the movable conveying roll  14  of the depositing device  3  are returned to their respective operating position and secured therein. The adjustment of the rolls  10 . 1  and  10 . 2  and of the conveying roll  14  can occur by a common drive, which permits a synchronous adjustment of the withdrawal system and the depositing device. However, it is also possible to adjust the conveying roll  14  independently of the rolls  10 . 1  and  10 . 2  of the withdrawal system  2 .  
         [0035]     In the case of the embodiments of the apparatus according to the invention and as shown in  FIGS. 1 . 1 ,  1 . 2 , and  2 , there basically also exists the possibility that during the operation, the movable rolls of the withdrawal system are previously moved to any position for adjusting defined degrees of looping. Thus, one could predetermine a plurality of operating positions, which are selected as a function of the denier of the tow for obtaining, for example, defined withdrawal forces.  
         [0036]     The embodiments shown in the Figures are suited for adjusting on the rolls  10 . 1  and  10 . 2  different operating positions with looping angles greater than 0° and smaller than 180°.  
         [0037]     The construction of the illustrated embodiments is likewise exemplary. Thus, they may comprise additional treatment devices as well as similar variants of configuration. For example, all rolls of a withdrawal system could be made movable for realizing a still greater flexibility in the configuration of the guide path and in the selection of the looping angles. Likewise, the adjustment of the depositing device may be realized by two movable conveying rolls.