Backrest and method for making backrest

Abstract

A backrest includes a frame, a web and a ring. The frame includes a margin and two rims extending on a side of the margin and a gap defined between the rims. The web is spread on the side of the frame. The ring is put on the web and fit in the annular groove so that the web is tightly spread on the frame.

1 . A backrest including: 
 a frame including a margin and two rims extending on a side of the margin and a gap defined between the rims;    a web spread on the side of the frame; and    a ring put on the web and fit in the annular groove so that the web is tightly spread on the frame.    
     
     
         2 . The backrest according to  claim 1  including a cushion arranged between the margin and the web so that the web is more tightly spread on the frame.  
     
     
         3 . The backrest according to  claim 1  including a cover installed around the frame.  
     
     
         4 . A method for making a backrest comprising the following steps: 
 providing a frame including a margin and two rims extending on a side of the margin and a gap defined between the rims;    providing a web;    providing a ring;    providing a mold assembly including: 
 a lower mold defining a cavity in an upper side;  
 a middle mold; and  
 an upper mold defining a cavity in a lower side;  
   putting the frame in the cavity of the lower mold with the rims facing up;    holding the frame in position by means of lowering the middle mold against the margin, with the rims exposed.    spreading the web on the middle mold, with the web covering the rims;    forcing the ring and an annular portion of the web into the annular groove so as to tightly spread the web on the frame;    pressing the ring, the web and the frame against one another by means of lowering the upper mold against the ring; and    adhering the frame, the web and the ring to one another;    returning the upper mold and the lower mold to their original positions; and    removing the frame, the web and the ring, as a whole, from the middle mold.    
     
     
         5 . The method according to  claim 4  wherein the step of adhering the frame, the web and the heat pressing the ring to one another includes a step of partly melting them.  
     
     
         6 . The method according to  claim 5  wherein the step of partly melting the frame, the web and the ring includes a step of heating them.  
     
     
         7 . The method according to  claim 6  wherein the step of heating the frame, the web and the ring includes a step of exerting high frequency on them.  
     
     
         8 . The method according to  claim 4  including a step of providing a cushion between the margin and the web so that the web is more tightly spread on the frame.  
     
     
         9 . The method according to  claim 4  including a step of providing a cover around the frame.