Hydro-forming of sheet with forming press halts punch once to raise medium pressure and then re-set with sheetholder force reduced during punch movement.

摘要

The movement of the punch (14) is halted at least once ahead of the end forming position and the pressure briefly raised and then lowered back to original level with the punch halted. Medium pressure is actively controlled during punch movement, being raised during punch travel against the force of the sheetholder (11) which in turn is lowered during punch movement. Medium pressure is raised after the punch has reached its end position. The forming layout comprises a punch (13) moving between start and end positions and a bottom tool (12) in container with its own feed (17) and bleed (19) for the medium. The sheetholder clamps the sheet edges as shown.