Clamping fixture for a tubular workpiece

Claim 1

A fixture for holding a tubular workpiece during the performance of a machining operation on the workpiece, said fixture comprising a pair of rigidly supported end members, a first stack of rings backed at its outer end by one of said end members, a second stack of rings backed at its outer end by the other of said end members, said workpiece being telescoped with said rings, said rings being made of resiliently yieldable material capable of expanding radially when compressed axially, means telescoped with said rings and restricting the rings against radial expansion away from said workpiece, and selectively operable means for compressing said rings axially against said end members whereby the rings expand radially toward the workpiece and into gripping engagement with the workpiece, said selectively operable means comprising a fluid operated actuator having a chamber and having a pair of pistons slidable within and disposed at opposite ends of said chamber, said chamber and pistons being generally annular and being located between the inner ends of said first and second stacks of rings and in coaxial relationship with said rings, and means for selectively admitting pressure fluid into said chamber to shift said pistons axially in opposite directions and thereby compress said rings axially between said pistons and said end members.