Rotatable Gripper for Paper Tubes

I have used conical and inflatable end inserts...

if I understand you, try doing a search for an iris type gripper

Try Schunk

Have you considerd vacuume?

You didn't specify as to how you wished to hold your part (sides, ends, internally) or your desired process direction (where and in which direction is the crimping). Also you didn't specify the wall thickness of the tubes you wish to process. Variables such as these often dictate what type of holding fixture you use. In the past I've often used vacuume for light parts in clean environments. It actually has surprising holding power on even delicate parts with no deformity if your fixture is well designed. While air pressure is often also a common and usually acceptable form of gripping a part if not properly designed it may deform the part in question. However if you were gripping from the inside then I would opt for air pressure. probably a pnumatic cylinder drawing down on a mandrel compressing an elastomer bushing forcing it to expand to the interior. Easy to set up and adjust for various loads and delicate parts or more agressive processes.