Hole punch for high-pressure shaping tool

摘要

A high-pressure shaping system has a tool defining a cavity and having a bore extending along an axis and opening into the cavity which is adapted to receive a workpiece which can be internally pressurized to expand and engage against inner surfaces of the cavity. A punch extending along the axis has an axially inwardly directed inner end displaceable between an inner position generally flush with the cavity inner surface and an outer position spaced axially outward of the cavity inner surface. A spring unit braced axially inward against the punch and axially outward against the tool has a spring characteristic with a high force/displacement ratio up to a break point and a low force/displacement ratio after the break point for urging the punch inward into the inner position.