Patent ID: 7237424
Filing Date: 2007-07-03
Classification: B21C,B21K

Abstract:
1. A method of forming a radially expandable externally grooved tubular fastener from metal, comprising the steps of: providing a suitable tubular blank having a tubular wall; and squeezing the tubular wall between a support pin with a surface which engages the internal tubular wall face of the blank and a plurality of external members provided with suitably shaped surfaces engaging the external tubular wall face of the blank; thereby to form grooves on the external tubular wall face of the blank; in which the squeezing is achieved by the effective decrease in diameter of the external members which are engaged with the external tubular wall face of the blank; and in which the external members are closed on to the external wall face of the tubular blank to form grooves thereon and then remain in the same spatial relationship with each other until they are withdrawn to release the blank, and wherein the internal tubular wall face of the blank is prevented from moving radially inwardly by the support pin.