Retractable energy absorbing webbing and method of manufacturing same

Abstract

Energy absorbing webbings that are generally flat and that have a controllable elongation distance are provided. The webbings are comprised of elongation yarns, such as partially oriented yarns (POY), and ground yarns. In certain embodiments, because they are generally flat, the energy absorbing webbings are suitable for use in retractors. Also provided are processes of manufacturing generally flat, energy absorbing webbings. In certain embodiments, the webbings are subjected to heat using first and second set of rollers with various feed ratios.

1 . A method of heat treating a webbing, the webbing comprising a plurality of elongation yarns and a plurality of strength member yarns, comprising:
 (i) feeding the webbing through a first set of rollers at a roll-in speed;   (ii) heat treating the webbing to adjust the relative lengths of the plurality of elongation yarns and the plurality of strength member yarns; and   (iii) feeding the webbing through a second set of rollers at a roll-out speed,   wherein the roll-in speed is different from the roll-out speed and is up to approximately 65% greater than the roll-out speed.   
     
     
         2 . The method of  claim 1 , further comprising providing the webbing, wherein the plurality of elongation yarns of the webbing are partially oriented yarns. 
     
     
         3 . The method of  claim 1 , wherein the roll-in speed is approximately 10 yards per minute and the roll-out speed is approximately 8 yards per minute. 
     
     
         4 . The method of  claim 1 , further comprising cutting the webbing to a predetermined length and then positioning the webbing within a retractor. 
     
     
         5 . The method of  claim 1 , wherein after the feeding the webbing through the second set of rollers, the elongation yarns are capable of sufficient elongation upon application of a predetermined load to absorb energy associated with a fall event. 
     
     
         6 . The method of  claim 5 , wherein the roll-in speed being greater than the roll-out speed results in a weave-in of the plurality of strength member yarns that is greater than a weave-in of the plurality of elongation yarns. 
     
     
         7 . A method of manufacturing an energy absorbing webbing, comprising:
 (i) providing a plurality of partially oriented yarns comprising an elongation distance;   (ii) providing a plurality of strength member yarns;   (iii) interweaving the plurality of strength member yarns and the plurality of partially oriented yarns in a warp direction along the webbing;   (iv) providing a plurality of lateral yarns in a weft direction along the webbing;   (v) feeding the webbing through a first set of rollers at a roll-in speed;   (vi) applying heat to the webbing as it is fed between the first set of rollers and a second set of rollers to adjust relative lengths of the plurality of elongation yarns and the plurality of strength member yarns; and   (vii) feeding the webbing through the second set of rollers at a roll-out speed,   wherein the roll-in speed is different from the roll-out speed.   
     
     
         8 . The method of  claim 7 , wherein the roll-in speed is up to approximately 65% greater than the roll-out speed. 
     
     
         9 . The method of  claim 7 , wherein the roll-in speed is approximately 10 yards per minute and the roll-out speed is approximately 8 yards per minute. 
     
     
         10 . The method of  claim 7 , further comprising positioning the webbing within a retractor. 
     
     
         11 . The method of  claim 7 , further comprising controlling the elongation distance of the partially oriented yarns by adjusting the roll-in speed relative to the roll-out speed. 
     
     
         12 . The method of  claim 7 , wherein the roll-in speed is greater than the roll-out speed, resulting in a weave-in of the plurality of strength member yarns that is greater than a weave-in of the plurality of elongation yarns such that the elongation yarns are capable of sufficient elongation upon application of a predetermined load to absorb energy associated with a fall event. 
     
     
         13 . A method of manufacturing an energy absorbing webbing, comprising:
 (i) providing a plurality of partially oriented yarns comprising an elongation distance;   (ii) providing a plurality of strength member yarns;   (iii) interweaving the plurality of strength member yarns and the plurality of partially oriented yarns in a warp direction along the webbing;   (iv) providing a plurality of lateral yarns in a weft direction along the webbing;   (v) feeding the webbing through a first set of rollers at a roll-in speed;   (vi) applying heat to the webbing as it is fed between the first set of rollers and a second set of rollers to adjust relative lengths of the plurality of elongation yarns and the plurality of strength member yarns; and   (vii) feeding the webbing through the second set of rollers at a roll-out speed,   wherein the roll-in speed is up to approximately 65% greater than the roll-out speed.   
     
     
         14 . The method of  claim 13 , wherein a weave-in of the plurality of strength member yarns is greater than a weave-in of the plurality of elongation yarns. 
     
     
         15 . The method of  claim 13 , further comprising positioning the webbing within a retractor.