Machine tool for production of rotationally symmetrical hollow body has piston compressing fluid in chamber between sealed piston members inside mandrel with profiled surface

摘要

The hollow cylindrical workpiece (1) fits over a generally cylindrical mandrel (2) and is held between two rings (10). The two rings bear on shoulders of upper and lower pistons (3,4) with a fluid-filled working chamber (6) between them. A piston (5) compresses the fluid, which is admitted (6a) to the inside of the mandrel. There are seals (8) on the upper and lower pistons. The outer surface of the mandrel has a profile, e.g. a screw thread, which may be forced into the inner surface of the workpiece. A small clearance is formed when the pressure in the working space is released.