Expansible shaft for roll core.

摘要

An elongate expansible shaft (10) for a roll core has a peripheral surface (16) defining multiple separate elongate slots (20) helically intertwined and oriented at a pitch angle no greater than about 30 DEG measured from a longitudinal axis (18). Each slot (20) is T-shaped in cross section and contains a respective separate, elongate, resilient bladder (28) pneumatically expandable into frictional engagement with the core. The bladder (28) has a unitary construction with hinge portions (32) for minimizing the loss of force due to expansion of the bladder. An air inlet fitting (56) is inserted in one end of each bladder (28) and is independently connected to a respective separate valve (82) for preventing the escape of air from the bladder irrespective of the air pressure in any other bladder. <IMAGE>