Patent Publication Number: US-7213310-B2

Title: Device for finishing denim woven fabric

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   Applicant claims priority under 35 U.S.C. §119 of German Applications Nos. 102 59 868.1 filed on Dec. 20, 2002 and 103 07 914.9 filed on Feb. 22, 2003. Applicant also claims priority under 35 U.S.C. §365 of PCT/DE03/03078 filed on Sep. 17, 2003. The international application under PCT article 21(2) was not published in English. 
   The invention relates to a device for finishing a denim textile web which, proceeding from unfinished goods, is supposed to be brought to predetermined reference values for finished width, skew and woof thread density, having a stretching device, for example a rack or hot flue, which has both stretching means for drawing the woven textile in its length, as well as slant positioning means for applying a skew, and having a shrinkage system assigned in continuous operation, preferably following the stretching device, having compression means for adjusting a woof thread density. Such a device is also referred to as a denim finishing line. 
   The denim process chain in the production of denim clothing, for example so-called jeans, proceeding from the unfinished woven textile, comprises so-called denim processing, also called woven textile finishing. This includes drying, stretching in length, and so-called skewing, as well as making the textile web shrink-resistant. In the case of the aforementioned skewing (English: skewing), the woven textile is drawn diagonally with reference to the warp and woof (skew). For this purpose, special slant racks are used, in practice. 
   Unfinished denim goods are normally produced at an unfinished width, e.g. 162 cm, which is clearly greater than the finished width, e.g. 151 cm. In order to obtain the finished width, the unfinished goods are drawn in length. The woof thread density (number of threads per unit of length), which is reduced as a result, is subsequently brought to the desired value in a shrinkage system, particularly having a rubber band shrinkage unit as the core machine. A measurement and regulation method, with which the reference value of the goods shrinkage to be achieved is determined and given to the rubber band shrinkage unit as a regulation value, is known from DE 43 23 715 A1. The residual shrinkage and the thread density per centimeter stand in a direct relationship with one another for a certain grade, i.e. if the fiber density at the exit of the finishing line is known the residual shrinkage value is also given. 
   Drawing the denim textile web in length can take place in a conventional rack, having a plurality of top and bottom rollers or, for example, also in a loop dryer, in short, a hot flue, if the latter possesses corresponding length stretching means. A suitable hot flue is described in DE 33 36 328 C2. It comprises a top series and a bottom series of guide rollers. In the known hot flue, the two series of guide rollers are mounted in a housing, parallel to one another and horizontally, essentially each in a plane. The housing possesses a horizontal inlet slit in an inlet wall, through which slit the textile web to be treated is to be introduced, spread out; analogously, there is an outlet slit in an outlet wall. 
   The (straight) connecting line between the inlet slit and the outlet slit defines the average transport direction of the textile web in the hot flue. In fact, however, the textile web is transported alternately over a bottom guide roller and a top guide roller, in loop shape or meander shape. Within the housing, rows of blowing nozzles are provided, arranged parallel to the guide rollers, which nozzles are used to blow treatment agents, particularly heated air (generally ambient air) onto the textile web, i.e. into the tensioned textile web loops. 
   Within the hot flue, the textile web is held under a predetermined lengthwise textile web tension, using web tensioning means that precede and follow the dryer. This lengthwise tension is supposed to be at least so great that even in the case of a goods content of thirty or more meters of textile web, it is ensured that the goods proceed through the hot flue essentially fold-free. 
   The skew of the woof threads, i.e. a slanted position of the woof threads relative to the warp threads of the woven textile that clearly deviates from 90°, is achieved, when using a conventional rack, for example, by setting part of the rack rollers at a slant. In most cases, the top rack rollers are raised vertically on one side (at their one longitudinal end), or the bottom rollers are lowered vertically at one end. 
   It has also been proposed already, as a means for setting a slanted position to produce a skew (German patent application 102 34 799.9 dated Jul. 31, 2002, not published prior to this invention), to provide a hot flue for denim goods, which has means for exerting a lengthwise draw (in other words stretching means) preceding and following it, and in the housing of which at least one group of at least one series of guide rollers can be tilted at a slant in one direction. The core of the related recognition is that a separate device for setting a slanted position can be entirely eliminated by setting at least part of the guide rollers of the hot flue at a slant. The remaining work result of the hot flue, which is normally expected, is not impaired by setting the guide rollers at a slant. 
   The invention is based on the task of bringing together in one system a stretching device, such as a rack or a hot flue with a subsequent width stretching field (for setting the goods width) and a rubber band shrinkage unit (as the core machine for an adjustable lengthwise shrinkage), and controlling the system in such a manner that the parameters of residual shrinkage, skew and width, which are decisive for determining how the goods turn out, remain reproducibly constant. In other words, the result to be achieved with the combined system is that when woven denim textiles are finished, predetermined reference values of textile web width, skew and woof thread density can be continuously obtained in one pass. 
   The solution according to the invention is indicated, for the device stated initially, in the characterizing part of claim  1 . Some improvements and additional embodiments of the invention are described in the dependent claims. 
   The device for finishing woven denim textiles, proceeding from unfinished goods, preferably comprises a rack or a hot flue as a stretching device, whereby the stretching device has both stretching means for lengthwise drawing of the woven textile and means for setting a slanted position, to apply a skew, assigned to it, and a shrinkage system that functions in continuous operation, having compressing means for setting a (particularly a predetermined) thread density. According to the invention, the device contains a single measuring device for detecting the actual values of goods width, skew and woof thread density, which is connected in a control circuit, in each instance, to control the stretching and slanted positioning means of the stretching device, on the one hand, and the compression means of the shrinkage system, on the other hand, to achieve the reference values, in each instance. 
   Preferably, the measuring device is supposed to immediately follow the stretching device (in other words particularly the rack or the width stretching field of the hot flue) or the shrinkage device. “Immediately follow” means, in this connection, that the supply of the textile web between the device to be controlled (rack or hot flue, respectively, or shrinkage device) and the measuring device is supposed to be minimal, in order to keep the amount of the goods that might have been treated incompletely, before the control circuit goes into effect, small. However, the least textile web loss in this sense is to be expected if the measuring device actually precedes the first textile web finishing stage, in other words generally the rack or the hot flue. Aids, e.g. web tension regulators, can be arranged between the device to be controlled and the measuring device. 
   The result achieved by means of the invention is that the reference values of textile web width, skew and woof thread density can be achieved in one pass, using a correspondingly configured rack or a correspondingly configured hot flue, and a shrinkage system, as well as a single measuring device, with continuous transport of the woven denim goods, which are finished in usual manner in the system. 
   In a first step, the textile web width (at the expense of the woof thread density) and the skew of the woof threads are adjusted to a predetermined reference value. In the subsequent second step, which is continuous, the woof thread density, which was previously reduced in the shrinkage system (during lengthwise stretching), is also brought to the predetermined reference value. According to the invention, both steps are controlled using one and the same measuring device. 
   Within the scope of the invention, an optical detector having a digital camera that can detect the thread density, the skew and the goods width is preferably used as the measuring device. In its measuring and regulation work, the detector is supposed to be guided crosswise to the transport direction of the textile web, traversing it, in order to achieve the result that it can register the textile web width, the amount of skew, and the woof thread density, all at the same time, and input them into the related control circuit. 
   If the measuring device follows the stretching device but precedes the shrinkage system, the following control pulses should be issued by it, for example by the digital camera having an optical detector (to achieve the reference values, in each instance):
     a) backwards to a mechanism that sets either the top or the bottom roller series of the rack or the hot flue at a slant, if necessary,   b) backwards to the pressure transducer of a pneumatically activated pendulum, for example, or to the reference value setter of a web force regulation system of the stretching device, which increase or decrease the goods tension as the goods pass through the stretching device, in interplay with a driven tension roller, so that the width can be changed in this manner, and   c) forwards to the stepper motor of the pressure roller of the rubber band shrinkage unit, so that the predetermined goods shrinkage is achieved by changing the rubber band contact pressure.   

   If the measuring device is positioned on the textile web ahead of the stretching device and ahead of the shrinkage system, all three parameters must be regulated forwards. It also lies within the scope of the invention to position the measuring device at the end of the finishing line, in other words following the shrinkage system, even immediately before winding the goods up, stacking them, or the like, so that the three parameters described above are all regulated backwards. 

   
     Details of the invention will be explained using the schematic representation of an exemplary embodiment having a hot flue as the stretching device. The drawing shows: 
       FIG. 1  a total system according to the invention, in vertical cross-section; and 
       FIG. 2  a cross-section along the line II—II of  FIG. 1 . 
   

   According to  FIG. 1 , a denim textile web  1  is guided through a first tensioning means  4 , from a roller  2 , in the transport direction  3 , into a hot flue designated as a whole as  5 , having a housing  6 . The housing  6  possesses an essentially horizontal inlet slit  7  with a deflection roller  8 , as well as, in the interior, two series  9  of guide rollers  11 . The textile web  1  is guided around the guide rollers  11 , in meander-shaped loops, upwards and downwards, and finally passed, by way of a deflection roller  12 , to a second tensioning means  14  through an outlet slit  13  of the housing  6 . Within the housing  6 , blower nozzles  17  are provided, which are directed into the textile web loops  16 , which are stretched out between two guide rollers  11  of a roller series  9 , in each instance. The lengthwise draw to be exerted on the textile web  1  within the hot flue  5 , in defined manner, is adjusted using a lengthwise draw control device  19 , between the two tensioning means  4  and  14 , in the direction of the average transport direction  18  of the textile web  1 . 
   In the exemplary embodiment according to  FIGS. 1 and 2 , the top guide rollers  11  are set in articulated bearings  22  at one of their longitudinal ends  21 , and mounted in a beam  24  at the other of their longitudinal ends  23 , which beam is held in a tilt bearing  26  at its one longitudinal end  25 , as shown in  FIGS. 1 and 2 , and rests on a slant positioning device  28  at its other (subsequent, in the web transport direction  2 ) longitudinal end  27 . The latter device has a slant positioning control device  29  assigned to it. In the transport direction  3 , the tilt bearing  26  and the longitudinal end  27  with the slant positioning device come first. 
   In the transport direction  3 , the tensioning means  14  according to  FIG. 1  are immediately followed, according to the invention, by a measuring device  30 . In the transport direction  3 , a shrinkage device  31  having a shrinkage control device  32  and compression means  33  follows. At the end, the finished woven textile can be rolled onto a roller  35  by way of a tension regulator  34 . 
   In the measuring device  30 , which is preferably configured as an optical detector having a digital camera, the goods width, the skew and the woof thread density are determined. The device expenditure remains relatively low, if the measuring device  30  is allowed to traverse the textile web  1  crosswise to the transport direction  2  [sic], for example on a rail arranged crosswise to the transport direction  3 . If the measuring head is appropriately controlled to move back and forth in defined manner, it is possible, in relatively simple manner, to measure the actual values of textile web width, skew and woof thread density achieved in the hot flue  5  (from the first tensioning means  4  to the second tensioning means  14 ) almost continuously. The values determined in the measuring device  30  in this way are passed to the control devices  19  and  29  (lengthwise draw and skew), as well as to the shrinkage control unit  32 , along the lines of effect shown with broken lines, in such a manner that a corresponding control circuit for achieving predetermined reference values is formed, in each instance. 
   According to  FIG. 1 , the measuring device  30  precedes the shrinkage device  31 . Alternatively, the measuring device can follow the shrinkage device. As an example, such a measuring device  30 ′, which is preferably configured just like the measuring device  30 , is shown with broken lines in  FIG. 1 . The related control lines (connections to the control devices  19 ,  29 , and  32 ) are characterized by dot-dash lines of effect. 
   In another preferred alternative, the measuring device  30 ″ actually precedes the first finishing stage, e.g. also the hot flue. The loss of incorrectly finished textile web yardage can then be kept very low. The lines of effect assigned to the position of the measuring device  30 ″ are shown with dot-dash lines. 
   REFERENCE SYMBOL LIST 
   
       
         1 =denim textile web 
         2 =roller 
         3 =transport direction 
         4 =first tensioning means 
         5 =hot flue 
         6 =housing ( 5 ) 
         7 =inlet slit ( 6 ) 
         8 =deflection roller 
         9 =guide roller series 
         11 =guide roller 
         12 =deflection roller 
         13 =outlet slit 
         14 =second tensioning means 
         16 =textile web loop 
         17 =blowing nozzles 
         18 =average transport direction 
         19 =lengthwise draw control device 
         21 =first longitudinal end ( 10 ) 
         22 =articulated bearing ( 21 ) 
         23 =second longitudinal end ( 10 ) 
         24 =beam 
         25 =first longitudinal end ( 24 ) 
         26 =tilt bearing 
         27 =second longitudinal end ( 24 ) 
         28 =slant positioning device 
         29 =slant positioning control device 
         30 ,  30 ′=measuring device 
         31 =shrinkage system 
         32 =shrinkage control device 
         33 =compression means 
         34 =tension regulator 
         35 =roller