Apparatus and method for shrinking continuous textile substrates

Abstract

An apparatus and a method for shrinking continuous textile substrates are described. The apparatus comprises: a first motorized roller; a second motorized roller; an endlessly wound belt for conveying and supporting the textile substrate; a pre-tensioning means for applying a predetermined longitudinal tension to the belt and a means for guiding the belt. According to the invention, the belt is substantially elastically deformable longitudinally. The pre-tensioning means comprises an idle roller and the guiding means comprises a rotating drum for guiding the belt along a length between the second motorized roller and the first motorized roller. The textile substrate is conveyed arranged between the belt and the rotating drum.

1 . An apparatus for shrinking a continuous textile substrate, said apparatus comprising: 
 a first motorized roller;    a second motorized roller;    an endlessly wound belt for conveying and supporting the textile substrate;    pre-tensioning means for applying a predetermined longitudinal tension to the belt; and    means for guiding the belt, said belt being substantially elastically deformable longitudinally;    wherein the pre-tensioning means comprises an idle roller; and    wherein said guiding means comprises a rotating drum for guiding the belt along a length between the second motorized roller and the first motorized roller, the textile substrate being conveyed arranged between the belt and the rotating drum.    
   
   
       2 . An apparatus according to  claim 1 , wherein said first motorized roller has an outer surface and said second motorized roller has an outer surface, and wherein the tangential speed on the outer surface of the first motorized roller is less than the tangential speed on the outer surface of the second motorized roller.  
   
   
       3 . An apparatus according to  claim 1 , further comprising a third motorized roller arranged downstream, with respect to an advancing direction of the belt and said first motorized roller, and connected to said first motorized roller so that the tangential speeds on the respective outer surfaces substantially coincide, the belt being wound at least partially around said third motorized roller.  
   
   
       4 . An apparatus according to  claim 3 , further comprising an idle roller for guiding said belt, the idle roller being arranged between said third motorized roller and said idle pre-tensioning roller, the belt being wound at least partially around said idle guiding roller.  
   
   
       5 . An apparatus according to  claim 1 , further comprising a fourth motorized roller being arranged upstream, with respect to an advancing direction of the belt and said second motorized roller, and connected to said second motorized roller so that the tangential speeds on the respective outer surfaces substantially coincide, the belt being wound at least partially around said fourth motorized roller.  
   
   
       6 . An apparatus according to  claim 5 , further comprising a fifth motorized roller arranged between said fourth motorized roller and said idle pre-tensioning roller and connected to said second motorized roller so that the tangential speeds on the respective outer surfaces substantially coincide, the belt being wound at least partially around said fifth motorized roller.  
   
   
       7 . An apparatus according to  claim 1 , wherein, during use, a first length of the belt substantially lying between said first motorized roller and said idle pre-tensioning roller and between the latter and said second motorized roller has a longitudinal extension greater than the longitudinal extension in the pre-tensioned condition.  
   
   
       8 . An apparatus according to  claim 7 , wherein said first belt length is the length between said idle guide roller, said idle pre-tensioning roller and said fifth motorized roller.  
   
   
       9 . An apparatus according to  claim 1 , wherein, during use, a second length of the belt substantially lying between the second motorized roller and the first motorized roller has a longitudinal extension less than or equal to the longitudinal extension in the pre-tensioned condition.  
   
   
       10 . An apparatus according to  claim 1 , wherein said rotating drum has a side surface for guiding at least part of said second length of the belt, said side surface of the drum being heated to a temperature higher than the ambient temperature.  
   
   
       11 . An apparatus according to  claim 1 , wherein said belt comprises a substantially extendable and elastic material, of natural origin, preferably based on rubber.  
   
   
       12 . An apparatus according to  claim 1 , wherein said belt comprises a substantially extendable and elastic material, of synthetic origin, preferably a polyurethane polymer or the like.  
   
   
       13 . An apparatus according to  claim 1 , wherein said belt comprises a substantially extendable and elastic material, of textile origin, preferably a felt supported by an extendable structure essentially consisting of elastic fibre.  
   
   
       14 . An apparatus according to  claim 1 , wherein said belt is elastically deformable in extension by a percentage ranging between 5% and 100% of its length in the untensioned state and, more preferably, equal to about 50% with respect to its untensioned length when subjected to a tensile force of about 3-12 kg/cm.  
   
   
       15 . An apparatus according to  claim 1 , wherein a distance between the surface of the drum and the surface of the second motorized roller is less than or equal to the thickness of the belt and a distance between the surface of the drum and the surface of the first motorized roller is greater than or equal to the thickness of the belt.  
   
   
       16 . A method for shrinking a continuous textile substrate, the method comprising the steps of: 
 providing an endlessly wound belt, said belt being substantially elastically deformable longitudinally in extension;    providing a first motorized roller and a second motorized roller, endlessly winding the belt between the first and the second motorized roller and applying a pre-tensioning pulling force to the belt;    driving the belt by means of the first motorized means and the second motorized means so that at least a first length thereof is subjected to a pulling force greater than the pre-tensioning pulling force and a second length thereof is subjected to a pulling force less than or equal to the pre-tensioning pulling force;    providing a treatment surface along the second belt length; and    feeding the continuous textile substrate so that it is conveyed arranged between the treatment surface and the belt along at least a portion of its second length.    
   
   
       17 . A method according to  claim 16 , wherein the step of providing a belt comprises the step of providing a belt which is elastically deformable in extension by a percentage ranging between 5% and 100% of its length in the untensioned state and, preferably, equal to about 50% with respect to its untensioned length when subjected to a tensile force of about 3-12 kg/cm.  
   
   
       18 . A method according to  claim 16 , wherein the belt conveying step comprises the step of providing a first motorized roller; a second motorized roller; an idle pre-tensioning roller; and a rotating drum for guiding the belt along its length between the first motorized roller and the second motorized roller, the tangential speed of said second motorized roller being greater than the tangential speed of said first motorized roller.  
   
   
       19 . A method according to  claim 18 , wherein the step of applying a pre-tensioning pulling force to the belt comprises the step of exerting on the belt a predetermined vertical thrust by means of the side surface of said idle roller.  
   
   
       20 . A method according to any  claim 16 , wherein the step of providing a treatment surface comprises the steps of providing an idle drum having an outer surface and heating said outer surface.  
   
   
       21 . A method according to  claim 18 , wherein the belt, along at least one portion of its first length, is more extended compared to its pre-tensioned condition by a percentage ranging between about 5% and 50%.  
   
   
       22 . A method according to  claim 16 , wherein the step of feeding the continuous textile substrate comprises the step of feeding a continuous textile substrate on the surface of the belt in the fully extended state and conveying the textile substrate on the belt in the state where fully contracted and subject to gradual untensioning.