Abstract:
An apparatus and a method for laying a tow into a can, wherein a tow feed device advances the tow into the can, with the tow feed device being movable to oscillate in a plurality of directions of movement. To obtain the highest possible flexibility when laying the tow into the can, the invention provides for moving the tow feed device by a multiaxial robot, which mounts the tow feed device at the free end of a robot arm.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     The present application is a continuation of international application PCT/EP2005/009710, filed Sep. 9, 2005, 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 for laying a tow into a can, as well as a method for laying a tow into a can, of the general type disclosed in DE 102 32 745 A1.  
         [0003]     In the known apparatus and method, a feed device advances a tow into a can. To control the deposit of the tow into the can, a movement control system reciprocates the feed drive in an oscillating manner in a plurality of directions of movement. To this end, the feed drive is mounted on a first pivotal support, which is adapted to be pivoted back and forth by a drive transversely to the direction of advance. The pivot axis of the first support is formed on a second support, which performs a superposed, transversely directly pivotal movement, so that the feed device is adapted to be guided in two orthogonal axes. To this end, the supports are arranged in a machine frame above the can, with the supports being adapted to be guided between two positions of deposit by means of a linear guideway.  
         [0004]     The known apparatus and the known method have in particular the advantage that the can being filled can be kept stationary in a position of deposit, while the tow is being deposited. The advance of the tow for being deposited into the can occurs exclusively by the movement of the feed device, so that the tow advances into the can in a controlled manner as a function of the respective position of the feed device.  
         [0005]     To optimize the filling of the cans regardless of their shape, a highest possible flexibility in laying the tow is desired in practical operation. In particular, there is a desire for high and uniform filling densities while taking into account an excellent withdrawal characteristic of the tow from the can in subsequent further processing.  
         [0006]     It is therefore an object of the invention to improve the known apparatus and the known method such that they accomplish a high flexibility in the deposit of the tow.  
         [0007]     It is a more particular object of the invention to provide an apparatus and a method, wherein any type of cans can be filled with a uniform and highest possible filling density.  
         [0008]     It is a further object of the invention to provide an apparatus and a method for laying a tow, which is easy to install regardless of the surroundings.  
       SUMMARY OF THE INVENTION  
       [0009]     The apparatus of the invention totally departs from the solutions so far known in the art. Thus, it is known to mount such laying apparatus together with upstream spin units in machine frames for purposes of obtaining a defined path of the tow until it is deposited into the can. The apparatus of the invention departs from the intent to arrange the tow feed device in a machine frame above the can. Rather, as a means of movement for the tow feed device, the invention utilizes a multiaxial robot, with the feed device being held at the free end of a robot arm. With that, it is possible to perform the movements of the feed device for advancing and laying the tow into the can with a maximal degree of freedom.  
         [0010]     Especially advantageous in this arrangement is the possibility of varying the spacing between the filling height inside the can and the feed device while filling the can. Thus, it is possible to enter the tow into the can at a constant drop height, which leads to an equalization of the deposit.  
         [0011]     According to an advantageous further development of the apparatus, the robot comprises at least three axes of movement, which permit realizing and controlling the movements of the feed device for laying the tow and filling the can. To fill the can, it is thus possible to perform three movements in superposed fashion to obtain a uniform deposit of the tow over the cross section of the can.  
         [0012]     To obtain a continuous flow of the tow when laying it, at least two cans are associated to the feed device, which can be alternately filled. In this case, it is especially advantageous to provide the robot with at least five axes of movement to be able to fill not only the individual cans, but also to alternate the positioning of the feed device relative to the cans.  
         [0013]     A further development of the apparatus according to the invention, comprises a deflection roll for guiding the tow and which precedes the feed device. This embodiment distinguishes itself in particular in that the tow may be supplied continuously and uniformly from an upstream treatment apparatus. The feed device and the deflection roll are preferably mounted to a support plate that is rigidly connected to the end of the robot arm.  
         [0014]     To prevent unacceptable reactions from the movement of the feed device on the advance of the tow, a further development of the apparatus according to the invention is especially preferred, wherein the movement of the robot arm is controlled such that the support plate performs a pivotal movement about a pivot axis that is formed by the axle of the deflection roll. With that, the advance of the tow remains unaffected by the pivotal movement of the feed device.  
         [0015]     A second pivotal movement is initiated preferably by the movement of the robot arm in such a manner that the support plate can be pivoted about a second pivot axis, which is formed as a tangent to the deflection roll at the level of the advancing tow. With that, no additional means are needed to prevent the tow from dropping from the deflection roll. The advance of the tow to the deflection roll remains largely unaffected by the laying motion of the feed device.  
         [0016]     To obtain a uniform advance of the tow at higher speeds, it is preferred to construct the feed device by two driven feed rolls, which interact for advancing the tow. However, other feed devices are possible, such as, for example, rolls with strippers or conveying belts.  
         [0017]     As cans for receiving the tow, one may use rectangular cans or also round cans.  
         [0018]     The method of the invention, wherein the direction of the movements of the feed device for laying the tow is freely selected and adjusted, distinguishes itself in particular in that the tow can be laid into cans of any shape with a uniform filling density. In particular, it permits generating laying patterns inside the can, which lead to an improved mass distribution of the tow inside the can. Also, it prevents pileups in reversal points when laying the tow.  
         [0019]     The flexibility in forming laying patterns in the can can be improved by varying and adjusting the amplitudes of the movements of the feed device and/or the speed of the movement of the feed device to lay the tow as a function of the geometry of the can. In this connection a maximal flexibility is reached, in that the movements of the feed device are varied and adjusted independently of one another in the direction of movement, the movement amplitude, and/or the speed.  
         [0020]     The method of the invention, wherein the sequence of movements of the feed device is predetermined by a control algorithm of a robot that guides the feed device with its arm, distinguishes itself in that it achieves not only a high flexibility in laying the tow, but also a very high reproducibility in filling the cans. The uniformity of the filling degrees of the individual cans has an advantageous effect in particular in further processing, since normally a plurality of individual tows are simultaneously removed from a plurality of cans and joined to a combined tow. Because of the uniform filling, there is also a guarantee for a uniform removal of the tow.  
         [0021]     To be able to perform an optimized deposit of the tow into the can as a function of process, fiber type, and can type, it is possible and advantageous to store a plurality of control algorithms for the robot, which are available to an operator for selection, so that a process adapted and optimized filling of the can is ensured.  
         [0022]     The apparatus and the method of the invention are especially suited for continuously laying into cans, in a two-step staple fiber process, synthetic multifilament fiber bundles that are combined to a tow. To this end, the apparatus of the invention is directly associated to a spin unit, by which one or more fiber bundles are spun from a polymer melt. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     In the following, the apparatus and the method of the invention are described in greater detail by means of several embodiments, with reference to the attached drawings, in which:  
         [0024]      FIG. 1  is a schematic front view of a melt spin line which embodies the present invention;  
         [0025]      FIG. 2  is a schematic side elevation view of the tow laying apparatus of the melt spin line shown in  FIG. 1 ;  
         [0026]      FIG. 3  is a schematic front view of the tow laying apparatus of the melt line shown in  FIGS. 1 and 2 ; and  
         [0027]      FIG. 4  is a schematic side elevation view of the apparatus shown in  FIG. 3 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]      FIGS. 1 and 2  schematically illustrate several views of a first embodiment of the apparatus according to the invention for carrying out the method of the invention, with  FIG. 1  being a front view of the complete production line and  FIG. 2  being a fragmentary view of the laying apparatus. Unless express reference is made to one of the Figures, the following description will apply to all Figures.  
         [0029]     The first embodiment illustrates a spin unit  1 , a withdrawal system  7 , a laying apparatus  18 , as well as a can station  19  to form a tow from melt spun fibers in one process step, and to deposit it into a can. To this end, the spin unit comprises a plurality of spinnerets  2 . 1 - 2 . 3  which receive a polymer melt under pressure. In the present embodiment, the melt preparation and melt supply are conventional and not described in greater detail.  
         [0030]     From each spinneret  2 . 1 - 2 . 3  a plurality of synthetic fibers are extruded and combined respectively to a fiber bundle  4 . 1 - 4 . 3 . To this end, a cooling apparatus  3 . 1 - 3 . 3  is arranged downstream of each spinneret  2 . 1 - 2 . 3  to cool the freshly spun fibers. Preferably, the cooling apparatus  3 . 1 - 3 . 3  are formed by air diffusers, with a generated cooling air stream flowing through the fibers from the inside outward. Downstream of the cooling apparatus  3 . 1 - 3 . 3  one or more lubrication rolls  5 . 1 - 5 . 3  are provided for combining the fibers to fiber bundles  4 . 1 - 4 . 3 .  
         [0031]     The fiber bundles  4 . 1 - 4 . 3  are combined to a tow  6  and removed from the spin unit  1  by the withdrawal system  7 . The withdrawal system  7  comprises a plurality of withdrawal rolls  8 , which are partially looped by the tow  6 . The withdrawal rolls  8  are driven, and they advance the tow  6  to the laying apparatus  18 .  
         [0032]     The laying apparatus  18  includes a tow feed device  10 , which is formed by two interactively driven feed rolls  11 . 1  and  11 . 2 . Upstream of the feed rolls  11 . 1  and  11 . 2  is a deflection roll  9 , which guides the tow  6  advancing from the withdrawal system  7 . The deflection roll  9  is mounted in cantilever fashion to a support plate  13 . On the backside of the support plate  13 , the deflection  9  connects to a motor  14 . Downstream of the deflection roll  9 , the feed rolls  11 . 1  and  11 . 2  are mounted in cantilever fashion to the support plate  13 . Each of the feed rolls  11 . 1  and  11 . 2  is driven by a drive  15  arranged on the backside of the support plate  13 .  
         [0033]     In the upper region lateral of the deflection roll  9 , the support plate  13  is rigidly connected to an arm  16  of a multiaxial robot  12 . For the robot  12 , it is possible to use a commercially available industrial robot of the type KR500 from Kuka. The support plate  13  can be guided and held by the robot arm  16  in a plurality of directions of movement.  
         [0034]     The robot  12  is shown arranged above the can station  19 . The can station  19  accommodates in side-by-side relationship two cans  17 . 1  and  17 . 2 , which are alternately available for receiving the tow  6 . The cans  17 . 1  and  17 . 2  may be made rectangular.  
         [0035]     Preferably, the robot  12  is arranged between the cans  17 . 1  and  17 . 2 . For laying a tow  6 , the robot arm  16  with the support plate  13  is selectively guided above the can  17 . 1  or above the can  17 . 2 . The position of the robot arm  16  and the support arm  13  above the can  17 . 2  is shown in phantom lines in  FIG. 1 .  
         [0036]     In operation, the fiber bundles  4 . 1 - 4 . 3  produced by the spin unit  1  are combined to a tow  6 . They are removed from the spin unit  1  by the withdrawal system  7  and supplied to the laying apparatus  18 . In the laying apparatus  18 , after being deflected over deflection roll  9 , the tow  6  is advanced by feed rolls  11 . 1  and  11 . 2 . To fill the can  17 . 1  held at the can station  19  while advancing the tow  6 , the robot arm  16  guides the support plate  13  with the deflection roll  9  and the feed rolls  11 . 1  and  11 . 2  in a plurality of directions of movement. The movements imparted by the robot  12  to the support plate  13  can be performed horizontally in a plurality of axes, or vertically, or as pivotal movement. In this process, the drives of the robot  12  are preferably activated by a control algorithm. However, it is also possible to adapt by individual interventions the movements in the direction of movement, the amplitude, or the speed to the respective process or the respective can present. To this end, it is possible to adjust and vary the direction of movement, the movement amplitudes, and the speeds.  
         [0037]     As soon as the can  17 . 1  is filled, a position change of the robot arm  16  occurs to the position shown in phantom lines. The robot  12  is activated to position the tow feed device  10  above the can  17 . 2 . As soon as a starting position of the tow feed device  10  above the can  17 . 2  is reached, a readjustment occurs in the robot  12  for activating the laying movements. The tow  6  is now being deposited into the can  17 . 2 . While the can  17 . 2  is being filled with the tow  6 , the full can  17 . 1  in the can station  19  is replaced with an empty can.  
         [0038]     The embodiment shown in  FIGS. 1 and 2  also permits using with advantage different shapes of cans in the can station  19 . For example, the tow  6  could also be accommodated in a round can. The laying movement of the robot  12  is controlled by a selectively stored control algorithm.  
         [0039]     In the embodiment shown in  FIG. 1 , the movement of the feed device for advancing and laying the tow  6  occurs substantially in a horizontal plane. To prevent length variations between the deflection roll  9  and the withdrawal system  7  while laying the tow, a further variant of the method for laying the tow  6  into the can  17 . 1  is shown in  FIGS. 3 and 4 .  
         [0040]      FIG. 3  is a front view of the laying apparatus  18  with can station  19 , and  FIG. 4  is a side view of the laying apparatus  18  with the can station  19 . Unless express reference is made to one of the Figures, the following description will apply to both Figures.  
         [0041]     The laying apparatus  18  is made identical with the foregoing embodiment, with a deflection roll  9  and two feed rolls  11 . 1  and  11 . 2  being mounted with their drives  14  and  15  to a support plate  13 . The support plate  13  is supported and guided by robot arm  16 . Arranged downstream of the laying apparatus  18  is a can  17 . 1 . The spacing between the support plate  13  and the upper edge of the can  17 . 1  is indicated by the capital letter H.  
         [0042]     To evenly fill the can  17 . 1  of a rectangular cross section with the tow  6 , the robot arm  16  causes the support plate  13  to perform two superposed pivotal movements.  
         [0043]     In  FIG. 3 , the movement amplitudes of a first pivotal movement are illustrated by pivoting angles α 1  and β 1 , with the can  17 . 1  being filled with the tow  6  over an unchanged spacing H. In this case, the support plate  13  with the tow feed device  10  is guided with a pivoting angle α 1  at the beginning of the filling. The movements of the robot arm  16  are controlled such that the support plate  13  performs a pivotal movement about the pivotal axis  20 . The pivotal axis  20  extends in the same direction as the axle of the deflection roll  9  and preferably is coaxial with the rotational axis of the roll  9 . As the degree of filling of the can  17 . 1  increases, the movement amplitude of the pivot movement increases up to the maximum pivoting angle β 1 . The movement amplitude that increases with an increasing degree of filling is stored in the control algorithm of the robot  12 , so that an automated laying of the tow is possible. By locating the first pivotal axis  20  along the axis of the deflection roll  9 , the feed of the tow  6  remains unaffected, so that no reactions are possible on the preceding withdrawal system  7 .  
         [0044]     In the case where the spacing H changes in proportion with the degree of filling, so as to attain a most uniform possible drop height of the tow, it will be possible to deposit the tow at a constant pivoting angle.  
         [0045]      FIG. 4  illustrates a second pivotal movement of the support plate  13 , wherein the feed device  10  is pivoted about a second pivotal axis  21 , which is tangent to the deflection roll at the level of the advancing tow  6  and preferably perpendicular to the first pivotal axis  20 . This ensures a maximum of smooth run of the tow  6  while being advanced. In this case, the movement amplitude changes likewise from a first pivoting angle α 1  to a maximal pivoting angle β 1 , provided the spacing H between the upper edge of the can  17 . 1  and the feed means  10  is kept constant. Likewise in this case, the possibility will apply that a varied spacing H permits filling the can with a constant drop height of the tow and at a constant pivoting angle of the pivotal movement.  
         [0046]     In the embodiment of  FIGS. 3 and 4 , the movements of the feed devices are controlled by a six axis robot. It was possible to ensure the advance of the tow to the feed device  10  exclusively by the illustrated deflection roll  9  without additional auxiliary means.  
         [0047]     The illustrated embodiments of  FIGS. 1-4  are exemplary in their construction. Suited as the feed device, are basically also rolls or conveying belts, which can be combined with an industrial robot for performing the laying movements. To fill a can, commercially available industrial robots are suited, which have at least three axes of movement, preferably five axes of movement and a corresponding carrying capacity.