Method of gripping tubular members during forming operations and

Abstract

A method of gripping a metal tubular member during a forming operation to resist damage to the gripped ends and reduce scrap, includes providing an outer tool having a recess structured to receive an end of the tubular member, inserting a resilient mandrel into the end of the tubular member and inserting the tubular member end into the recess. A compressive force is applied to the resilient member in a direction aligned generally axially of the tubular member to establish transverse expansion of the resilient member in order to clamp the tubular member end between the mandrel and the outer tool recess. The tube may be stretched beyond the yield point and formed while so clamped, after which the compressive force is removed so as to facilitate withdrawal of the formed tube. In one embodiment, the mandrel may consist of a composite which may have a lower durometer hardness inner portion and higher durometer hardness outer portions. In another embodiment, a substantially rigid mandrel is received within the tube end and an annular resilient sleeve is positioned on the outside of the tube end. The method may be used for a wide variety of purposes including forming structural vehicular members. Associated apparatus is provided.