| 摘要 |
Members of an assembly, a first of which has an aperture (80) and a second of (84) which is of deformable sheet-like material, are fastened together by piercing and deforming the second member (84) using a punch and die to provide a pierced aperture (70) having a peripheral wall of helical (76) form analogous to a screw-thread, assembling the members (80,84) together with the apertures aligned, inserting a tubular fastener (90) having a head (94) and a shank (92) into the apertures so that the head (94) abuts a face of the first member (80) and the shank (92) extends through the second member (84), and then expanding at least part of the shank (92) within the pierced aperture (70) of the second member (84) and thereby causing the peripheral wall of the pierced aperture (70) to impress a helical peripheral groove into the external surface of the shank (92) of the fastener (90). The shank (92) can be expanded by pulling a tapering mandrel head (104) into or through it. The fastener (90) is made to facilitate its removal by unscrewing from the fastened assembly by providing or forming wrenching surfaces in its bore or on its head for engagement with a key, screwdriver, spanner or the like. <IMAGE> |
