Compression apparatus and method

Abstract

A resilient unit is fed as a continuous web 18 through first and second tensioning rollers 20, 22 to a winding roller 24. The winding roller is driven at a first speed, and one or both of the tensioning rollers is also driven, but at a second speed which is less than the first speed—i.e. slower than that of the winding roller. The difference is speeds causes tension to be applied to the material of the resilient unit which stretches the resilient unit and in turn compresses the resilient elements in their pockets. The result is that the resilient unit becomes compressed in its through thickness direction—the axial direction of the springs—before it is wound into the winding roller. The resilient unit extends in length in a longitudinal direction in which tension is applied. The extension in length is substantially proportional to a reduction in a thickness of the resilient unit.

1 . Compression apparatus arranged to compress a resilient unit comprising a plurality of resilient elements located within one or more pockets formed between layers of material, the apparatus comprising tensioning means arranged to apply tension to the material, and winding means arranged to wind the material into a roll, wherein the application of tension to the material causes the resilient elements to become compressed prior to winding into the roll, thereby causing the resilient unit to take up less volume. 
     
     
         2 . Apparatus according to  claim 1 , wherein the winding means comprises a winding roller. 
     
     
         3 . Apparatus according to  claim 2 , wherein the apparatus is arranged to place the resilient unit in tension by pulling the material between the winding roller and the tensioning means. 
     
     
         4 . Apparatus according to  claim 2 , wherein the tensioning means comprises one or more tensioning rollers, through or against which the resilient unit is arranged to pass. 
     
     
         5 . Apparatus according to  claim 4 , wherein the winding roller and at least one tensioning roller are allowed or caused to rotate at different speeds to apply tension to the resilient unit. 
     
     
         6 . Apparatus according to  claim 1 , wherein the application of tension to the material in a longitudinal direction of the resilient unit is arranged to cause the material to compress the resilient elements between the layers of material. 
     
     
         7 . Apparatus according to  claim 1 , wherein the application of tension to the material in a longitudinal direction of the resilient unit is arranged to bring about an extension of said unit in said longitudinal direction that is substantially proportional to a reduction in a thickness of the resilient unit. 
     
     
         8 . Apparatus according to  claim 1 , wherein the resilient elements comprise springs. 
     
     
         9 . Apparatus according to  claim 1 , wherein the resilient unit comprises a pocketed spring unit. 
     
     
         10 . A method of compressing a resilient unit comprising a plurality of resilient elements located within one or more pockets formed between layers of material, the method comprising applying tension to the material so as to cause the resilient elements to become compressed and winding the material under tension into a roll 
     
     
         11 . A method according to  claim 9 , wherein the method comprises winding the material using a winding roller. 
     
     
         12 . A method according to  claim 10 , wherein the method comprises applying tension to the resilient unit by pulling the resilient unit between the winding roller and tensioning means. 
     
     
         13 . A method according to  claim 11 , wherein the method includes pulling the resilient unit between the winding roller and one or more tensioning rollers. 
     
     
         14 . A method according to  claim 12 , wherein the method comprises allowing or causing rollers to rotate at different speeds to cause the tension to be applied to the material of the unit between the winding roller and the or each tensioning roller.