A novel ironing punch concept with adjustable tool diameter

A new tool concept is presented. It reduces galling and tool wear by lowering the interface pressure between workpiece and tool during retraction. The work performed during retraction of a prototype ironing punch is reduced by more than 50% compared to a conventional punch. This is achieved by a hollow punch with an internal mandrel, which provides stiffness during ironing through a conical interface, while the punch contracts during retraction when the mandrel is released. Adjustability of the punch diameter by the mandrel position enables adaptation to variable external factors, e.g. variation of strip thickness in progressive die forming.