GB1515038A - Fastener system - Google Patents

Abstract

1515038 Bolting; rivets JOKING 10 June 1976 24082/76 Heading F2H [Also in Division B3] A fastener assembly for securing together members P with aligned holes H therethrough comprises a fastener F and a separate holesizing collet C, the fastener comprising a shank with an enlarged head 16 at its rear end, a bearing section 14, and a forward facing driving face 20 normal to the fastener axis at its leading end, and the collet C having an outer surface which enlarges progressively from a minimum diameter d PC at its leading end to a maximum diameter d EM (Fig. 6) and having at its trailing end a rearward facing driven face 50 normal to the collet axis to be engaged by the fastener's driving face 20 to force the collet through the holes H, and alignment means for maintaining the fastener and collet coaxial as they are forced into the holes H with the collet leading the fastener bearing section. The collet C enlarges the holes H to produce a predetermined interference fit with the bearing section 14 of the fastener. In Figs. 1, 6, 16 the fastener has adjacent the bearing section 14 an engagement section 15 which either is threaded to receive a nut or has annular locking grooves to receive a swaged-on collar. The fastener F is connected by a breakneck 21 to a collet support S comprising a support section 25 to slidably receive the collet C so that its driven face 50 abuts the driving face 20, and a pulling section 22 to be gripped by a conventional lockbolt installation gun. An indicator band 55 on the pulling section is visible to the gun operator when the collet C abuts the opposite side NS of the members P. A washer (BW) (Fig. 17, not shown) may be placed between the nose of the installation gun and the surface OS of the adjacent member P to prevent extrusion of material round the hole H as the collet is forced through the holes. With the fastener installed and the collet removed, the lockbolt installation gun can be used with an adaptor 500, Fig. 19, to preload the fastener while a nut NT is tightened. The adaptor fits over the nose of the gun and is spaced from the member P by shouldered bolts 510. A hexagonal socket DE fits over the nut and is connected via a ratchet (not shown) to a wrench handle DH. In Fig. 10, the collet C is a wire coil member 211 and is supported by a frusto-conical support section 225. In Fig. 4, the collet 325 is integral with the support section and the pulling section 322, this integral unit 311 being separate from the fastener F and having at its trailing end a plain cylindrical boss 345 which engages in a hexagonal broached socket (321) (Fig. 11, not shown) in the leading end of the fastener to align the fastener with the unit 311. In Fig. 5 the collet support section 424 and the pulling section 422 form one unit S, the section 424 having a hooked trailing end 474 which can engage with a hooked part-cylindrical boss 460 at the leading end of the fastener, the boss 460 forming with the section 424 a continuous cylindrical support surface for the collet C, the collet locking the fastener F and unit S together. The hook formations may have interengaging V-nose and V-notch portions (481, 480) (Figs. 14, 15, not shown). In Fig. 22 (and Fig. 2, not shown) the fastener has a shank with two opposed frusto-conical portions 115 R , 115 F tapering to a minimum diameter approximately where the shank will lie at the interface of the two members 9 when installed. In a shear joint, no engagement section is needed on the fastener as it is retained solely by the interference fit of the tapered shank portions. In a modification, a single taper 115 R extends from the breakneck 121 to the head 116. In Fig. 26 a cap 600 of soft absorbent resilient material is pushed over the leading end of the pulling section 22. The cap is impregnated with a lubricant and/or sealant to line the holes H, and also serves to clear any burrs or swarf from the holes as it is pushed through them. In all cases the sizing collet and the fastener are forced into the holes H using a lockbolt installation gun (LG) to pull the pulling section 22 and a rivet gun (RG) to drive the fastener head 16 (Fig. 21) the rivet gun being operable only when the gun LG is actuated.