Abstract:
A method of strengthening a conveyable fiber lap in an endlessly circulating conveying device is provided. The method includes conveying the fiber lap using first and second converging rollers, each roller having an outer surface, at least the first roller being provided with profile elements on its outer surface, the profile elements being non-continuous in an axial direction of the first roller; subjecting the fiber lap to a pressure when the fiber lap passes through a gap between the first and second rollers; and strengthening the fiber lap by exerting the pressure by the converging rollers and the profile elements.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a continuation of U.S. patent application Ser. No. 10/260,418, filed Oct. 1, 2002 now U.S. Pat. No. 6,704,969, the disclosure of which is incorporated herein by reference. This application claims priority to German Patent Application No. 101 56 734.0, filed Nov. 19, 2001, the disclosure of which is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   The invention relates to a device for strengthening a conveyable fiber lap made, for example, of cotton, synthetic fibers or the like. The device comprises at least one endlessly circulating conveying device having, for example, two rollers. The outer surfaces of the rollers can convey the fiber lap and are provided with elements that engage the fiber lap and have a strengthening effect on the fiber lap. 
   In practical operations, fiber laps are subjected to repeated needle treatments with needle boards for strengthening the laps. In the process, the lap is stressed in a lap movement direction since the needles plunging into the lap during the needle treatment delay the lap relative to a continuous lap movement. In many cases, this leads to an undesirable longitudinal stretching of the lap. U.S. Pat. No. 5,909,883 discloses a withdrawing roller drive control that reduces the withdrawing speed during the needle intervention to take into account the lap withdrawing resistance which increases as a result of the entering needles. However, the design and control expenditure required for the drive control is comparably high. 
   Austrian Patent No. 259 246 B1 discloses reducing the tensional stress of the fiber lap during the needle insertion by designing one of a pair of withdrawing rollers such that it has diametrically opposite arranged driver cams for the fiber lap. Depending on the lift frequency of the needle board, a frictional connection between the withdrawing rollers and the lap results only if the lap is released by the needle board. An intermittent lap conveying drive of this type represents an advantageous precondition for a low-draft needle-treatment of the fiber lap, but also requires an even lap thickness that cannot be ensured in practical operations. Unavoidable thick and thin areas in the lap cause irregularities in the lap advancement, thus resulting in an irregular needle-treatment. In addition, thick areas in the lap can result in surface damage to the lap caused by the driver cams for the withdrawing roller which impacts the lap, possibly leading to a mechanical overload for the withdrawing rollers, particularly in the bearing region. 
   The known intermittent needle insertion has the further disadvantage of preventing a high operating speed. A previous suggestion called for the needles to be arranged rigidly on the outside surface of a belt that endlessly circulates around two deflection rollers. In the process, the fiber material is drawn, meaning a relative movement takes place between the needles and the fiber material. While the needles are inserted into and pulled out of the fiber material, at the two deflection locations, additional relative movements occur between the needles and the fiber material because the needles are positioned at a slant relative to the fiber material. These movements lead to drafts in a longitudinal direction and, in particular, to an uneven structure of the fiber material. 
   SUMMARY OF THE INVENTION 
   Thus, it is an object of the invention to create a device of the above-described type that avoids the aforementioned disadvantages and, in particular, permits a high strengthening speed and a higher strengthening of the fiber lap. 
   Particular embodiments of the invention provide an endlessly circulating conveying device for strengthening a conveyable fiber lap. The device has first and second converging rollers for conveying the fiber lap. Each roller has an outer surface and at least the first roller is provided with profile elements on its outer surface. The rollers are for subjecting the fiber lap to a pressure when the fiber lap passes through a gap between the rollers, and strengthening the fiber lap by exerting the pressure by the converging rollers and the profile elements. 
   The invention makes it possible to realize a high strengthening speed and high strengthening of the fiber lap. Two cooperating rollers permit a high circumferential speed and thus a high conveying speed for the fiber lap. The profiled rollers make it possible to have a high strengthening without damaging the fiber lap. In particular, the movement through the converging roller gap results in a pre-strengthening and the profile elements locally (in some locations) cause a main strengthening of the pre-strengthened fiber lap. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is explained below in further detail with the aid of exemplary embodiments shown in the drawings, wherein: 
       FIG. 1  is a schematic side elevation view of a carding machine provided with a device according to the invention; 
       FIG. 2  is a partial side elevation view of the carding machine according to  FIG. 1 , with two ascending gathering rollers; 
       FIG. 3  is a front view of the card discharge according to  FIG. 1 , comprising two profiled rollers that are connected downstream of the withdrawing rollers; 
       FIG. 4  shows an embodiment of the invention having a profiled roller and a smooth roller; 
       FIG. 5   a  shows two profiled rollers installed downstream of a sliver trumpet; 
       FIG. 5   b  is a front view of a profiled roller according to  FIG. 5   a;    
       FIG. 6   a  is a side view of sawtooth clothing for the profiled roller(s); 
       FIG. 6   b  is a section along line I—I in  FIG. 6   a  through two teeth of the sawtooth clothing, arranged side-by-side with wire in-between; 
       FIG. 6   c  shows the teeth according to  FIG. 6   b , without the wire in-between; 
       FIG. 7  is a front view of a profiled roller, composed of side-by-side arranged toothed disks with spacers inserted between them; 
       FIG. 8  shows a first embodiment of the toothed disks according to  FIG. 7  with approximately trapezoid profile projections along the circumference; 
       FIG. 9  shows a second embodiment of the toothed disks according to  FIG. 7  with convex curved profile projections along the circumference; 
       FIG. 10  is a front view of a profiled roller with profile elements; 
       FIG. 11  is a schematic representation of the distances between the basic roller bodies and the profile elements for the pre-strengthening and the main strengthening; and 
       FIG. 12  is a perspective view of a fiber lap (sliver) trumpet with a rectangular discharge region. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1  shows a carding machine, for example a high-performance Model DK 903 by the company Trützschler in Mönchengladbach, Germany. The carding machine comprises a feed roller  1 , licker-ins  3   a ,  3   b ,  3   c , a main carding cylinder  4 , a doffer  5 , a stripping roller  6 , a lap-gathering element  7 , withdrawing rollers  11 ,  12  (roller  11  being behind roller  12  and, therefore, not visible in FIG.  1 ), two profiled rollers  21 ,  22 , and traveling flats  13  with slowly circulating flat bars  14 . Curved arrows indicate the rotational directions of the rollers while arrow A indicates the operating direction (fiber material flow direction). 
   Two gathering rollers  18 ,  19 , which gather the fiber material to form a heavy fiber lap, are arranged between the doffer  5  and the stripping roller  6 . The stripping roller  6  rotates clockwise and drops the fiber material from above into the lap-gathering element  7 . The lap-gathering element  7  in this example is funnel-shaped (see  FIG. 3 ) and is positioned vertically. The two withdrawing rollers  11 ,  12  (see  FIG. 3 ) are positioned at the lower end of the lap-gathering element  7  and are followed (in a downward direction) by the two profiled rollers  21 ,  22  (see FIG.  3 ). 
   As shown in  FIG. 2 , the gathering rollers  18  and  19  and the stripping roller  6  are arranged in ascending order, following the doffer  5 . The fiber material is raised to a specific height and the lap-gathering element  7  can be arranged underneath the stripping roller  6 . The released fiber lap then drops downward, aided by the forces of gravity, and into the lap-gathering element  7 , which supports the flow of material. The withdrawing rollers  11 ,  12  withdraw the strengthened fiber lap from the discharge opening of the lap-gathering element  7 . The two profiled rollers  21 ,  22  ( FIG. 3 ) or one profiled roller  22  and one smooth roller  21 ′ ( FIG. 4 ) can be used. 
   As seen in fiber material flow direction, the lap-gathering element  7  shown in  FIG. 3  is provided with a lap-gathering region and a lap-strengthening region. In  FIG. 3 , the lap-gathering element  7  has a lap-guide element  9  that forms the lap-gathering region and a lap trumpet  10  that forms the lap-strengthening region. The lap-guide element  9  and the lap trumpet  10  are, in this example, closed on all sides, except for the respective intake and discharge openings for the fiber material. The intake opening for the lap-guide element  9  is arranged at a distance f to the stripping roller  6 , for example approximately 50 mm. The profiled rollers  21 ,  22 , which convey the fiber material further and strengthen it, are arranged downstream from the withdrawing rollers  11 ,  12 . In this example, roller  12  is spring-loaded by spring  20 . The axes for the withdrawing rollers  11 ,  12  and the profiled rollers  21 ,  22  are aligned parallel to each other. The fiber lap exiting from the trumpet  10  respectively passes with its broad side (corresponding to a in  FIG. 12 ) through the gap between the rollers  11 ,  12  and  21 ,  22 . 
   In the example shown in  FIG. 4 , the lap-gathering element  7 ′ has a one-piece design. The discharge region for the lap-gathering element  7 ′ corresponds to the discharge region  10   a  (see  FIG. 12 ) of the fiber lap trumpet  10  and extends into the gap between the immediately following roller pair, in this example profiled roller  22  and smooth roller  21 ′. 
   All wall surfaces of the lap-gathering element  7 ,  7 ′ shown in the embodiments of  FIGS. 3 and 4 , are stationary during the operation, meaning the fiber material glides along the inside wall surfaces of the lap-gathering element  7 ,  7 ′. Curved arrows indicate the rotational directions of the rollers  11 ,  12  and  21 ,  22 . 
     FIG. 5   a  shows two profiled rollers  21 ,  22 , provided with an endless solid-steel clothing  21   a  or  22   a , which is respectively oriented toward the roller body  21   b  or  22   b . The roller  21  rotates according to the arrow  21   c  in a counter-clockwise direction and the roller  22  rotates corresponding to arrow  22   c  in a clockwise direction. The discharge from the lap-gathering element  7  extends into the gap between the profiled rollers  21 ,  22 . The lap-gathering element is followed immediately by the two profiled rollers  21 ,  22 . The front view of the roller  22  in  FIG. 5   b  shows how the clothing  22   a  is wound helically around the basic roller body  22   b.    
   One example of geometric data of the sawtooth clothing  21   a ,  22   a , selected according to DIN (German Industrial Standard) 64 125, is shown in  FIGS. 6   a ,  6   b . In another embodiment of the invention, the clothing consists of wire needles. 
   The sawtooth clothing is shown in  FIG. 6   a  as a stretched wire with a plurality of teeth  21 ′ 1 , for example having a height h 1  of 2.5 mm. Each tooth  21 ′ 1  has a short, straight zone  1   8  at the tooth tip  21 ′ 4 , for example 0.6 to 1.5 mm, which is oriented parallel to the base plane  21 ′ 9  of the tooth base  21 ′ 2 . Each tooth  21 ′ 1  furthermore has a tooth front  21 ′ 5  and a tooth back  21 ′ 6 . The front angle α is 0°. The angle δ, the angle between the straight zone of the tooth tip  21 ′ 4  and the perpendicular line relative to the tooth base plane  21 ′ 9  of the tooth base  21 ′ 2 , amounts to 90°. 
   The back angle γ, the angle between the straight zone  21 ′ 4  and the perpendicular line is 90°. The tooth region above the tooth base  21 ′ 2  is given the reference  21 ′ 3  and has a height h 2 . A tooth gap  21 ′ 7  respectively exists between a tooth front  21 ′ 5  and a tooth back  21 ′ 6  of two adjacent teeth  21 ′ 1 . The tooth gap  21 ′ 7  has two arcs of approximately one fourth of a circle and a gap bottom  21 ′ 8  that connects the two arcs. The radii of the two arcs for the tooth gap  21 ′ 7  are identical to the tooth radii r′ z  and r″ z , for example amounting to approximately 0.6 mm. The tooth gap height h 3  is approximately 0.6 mm to 1.5 mm. The tooth division t (on the stretched wire) is approximately 2.45 mm to 2.85 mm. 
   The two teeth  21 ′ 1 , shown in a sectional view in  FIG. 6   b , have a pitch P. A spacing wire  31  is arranged between the teeth  21 ′ 1  which is wound endlessly around the roller body  21   b , in the same way as the sawtooth clothing. However, according to  FIG. 6   c  the teeth  21 ′ 1  can also be arranged immediately adjacent to each other, without any spacing in-between. The tip width b s  of tooth  21 ′ 1 , for example, can be more than 0.2 mm and less than 1 mm. The base width b F  of the tooth  21 ′ 1  can be more than 1 mm and less than 4 mm, for example 2 mm. The tooth density T=10/t can be approximately 3.5 to 4.0/cm. The number of windings per unit z=10/b F  can be approximately 4.8 to 5.2/cm and the density=G×T can be approximately 18.5 to 19.5 cm 2 . 
   As shown in  FIG. 7 , the profiled roller  21 ,  22  can be configured as a disk-type roller. Profiled disks  24 ,  25  (see  FIGS. 8 ,  9 ) are arranged side-by-side on a shaft  23 , wherein one spacing disk  26  is provided between two adjacent disks  24 ,  25 . Holding elements  27   a ,  27   b  are respectively arranged on the two ends of the disk packet. The holding elements are secured, for example, with screws and hold together and press together the disks  24 ,  25  and spacers  26 . 
   In the example shown in  FIG. 8 , the profile elements  24   a  along the circumference of disk  24  are shaped in the manner of a trapeze or pyramid. Disk  24  is provided, in this example, with a keyed hole  24   b  for mounting on shaft  23 . In the example shown in  FIG. 9 , the profile elements  25   a  along the circumference of disk  25  are shaped approximately semi-circular or semi-spherical. Disk  25  is provided, in this example, with a keyed hole  25   b  for mounting on shaft  23 . Different profile element shapes that are suitable for the primary strengthening can be used as well. 
     FIG. 10  shows an embodiment where the profile elements  24   a ′ and  25   a ′ are arranged directly on the basic roller body. In  FIG. 10 , the profile elements  24   a ′,  25   a ′ are arranged offset to each other. The lap strengthening can be improved by such a roller. The spacing of the profile elements in a width direction is indicated by d and the offset in the rotational direction between adjacent profile elements is indicated by e. 
   In  FIG. 11 , the pre-strengthening occurs between the outer surface  12   b  of roller  12  and the outer surface  24   b  of disks  24  and the main strengthening occurs between the outer surface  24   b  and the exposed end of the profile element  24   a . The distance between the outer surface  12   b  and the outer surface  24   b  is indicated by f and the distance between the outer surface  12   b  and the exposed end of the profile element  24   a  is indicated by g. The pre-strengthening and the main strengthening occur in the same way as for the profiled rollers with sawtooth clothing, shown in  FIGS. 5   a ,  5   b  and  6   a ,  6   b.    
   According to  FIG. 12 , the discharge opening  10   a  of the fiber lap trumpet  10  has a height b of approximately 2 to 3 mm. The width a of the discharge opening  10   a  for the trumpet  10  is at least approximately 30 to 100 mm, preferably approximately 2 to 30 mm. Wall elements  10   c  and  10   d  define sides of the discharge opening  10   a . The width a can be changed by displacing wall element  10   c  in the region of the discharge opening  10   a  in the direction of arrows D, E. The rectangular region  10   a  is designed with sharp edges. In this way, the flat fiber lap that exits the lap trumpet has a sharp-edged cross-sectional shape. 
   The invention has been described in detail with respect to preferred embodiments and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects. The invention, therefore, is intended to cover all such changes and modifications that fall within the true spirit of the invention.