COMPRESSION APPARATUS AND METHOD

摘要

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.