Production process for circumferentially closed tube involves reverting bent-in hole edge to unbent state using hole punch without relieving internal high pressure

摘要

The tube production process involves producing a tube (5), initially with a hole, by applying an internal high pressure deformation tool. The edge (15) of the hole bent into the interior (13) in producing the hole is reverted to the unbent state by using the hole punch without relieving the high pressure. and then reducing the pressure while the dolly (12) is still inside the tube at the endface of the punch (11).