Method of making a tubular body having a deformable internal skirt

Abstract

A tubular body (74, 102) having a deformable internal annular skirt is made from a blank (10, 80) having a stopped bore (20) which terminates at an end wall (24). First, an aperture (40) is formed in the end wall (24) to provided a through bore, of which a main region is provided by the formerly stopped bore (20). The aperture (40) is made to taper towards the main region and to a diameter substantially smaller than that of the main region. Material peripherally of the aperture (40) is then swaged towards and into the main region, and radially outwardly in the main region, thereby forming the swaged material into a skirt. The tapering aperture (40) can be formed by use of a punch (30) and a die (32) having a die aperture (36) larger than the punch diameter. By making the aperture (40) not radially symmetrical, the resulting skirt (70, 98) can be made of unequal lengths on opposite radii. The aperture (114) can be made non-symmetrical by using a punch slightly offset from the axis of the die aperture (36) or by making the end wall of different thickness on different radii.