Patent GB-1149467-A (GB)
Title: Connecting fastener members to thermoplastic sheets
IPC: B29C65/06
Filed: 1967-09-29
Abstract: 1,149,467. Seaming non-metallic sheet material. UNIROYAL Inc. 29 Sept., 1967 [19 Oct., 1966], No. 44342/67. Heading B5K. A fastener member 1 is joined to a thermoplastic body 2 by positioning an end of the fastener against the body with an axis of symmetry of the fastener directed into the body, spinning the fastener relative to the body at a speed sufficient to create enough heat to melt the material of the body where the fastener and the body are in frictional contact, simultaneously applying pressure between the fastener and the body in a direction parallel to the axis of the fastener to displace the fastener into the body, terminating the spinning and pressure application when the fastener has been displaced to a required extent, and allowing the body to cool whereby the molten material solidifies to secure the fastener to the body. Preferably the fastener is made of a material identical to or compatible with the material of the body 2 but, alternatively, the fastener 1 may have a roughened surface and be made of a relatively stiff non-thermoplastic material having a softening temperature above the melting temperature of the body 2, e.g. metal or a cured epoxy resin. In one embodiment, Fig. 1, an L-shaped extruded aluminium moulding 3 is secured by a number of fasteners 1 to an edge 4 of a thermoplastic sheet 2 composed of an expanded core 2b sandwiched between thin walls 2a. Each fastener 1 may be moulded from granular plastics material and comprises a head la cut to receive a screwdriver blade and a tapered stem 1b. Openings 5 in the moulding 3 having a diameter substantially equal to the width of the core 2b and the body of each fastener 1 includes a portion with a diameter slightly less than the width of the core 2b so as to be able to pass through the opening 5 upon spinning the fastener 1 relative to the sheet 2 by a power-operated screwdriver to effect the joining. The method may be carried out using a hand-held power drill. In another embodiment, Fig. 2, two expanded core-type thermoplastic sheets 2, 3a are joined together using a fastener 1<SP>1</SP> similar to that of Fig. 1 but having no head. Before the sheets are assembled, an opening or openings 5<SP>1</SP> is or are punched or drilled in the sheet 3a. The diameter of the bore of each opening 5<SP>1</SP> is 5-10% smaller than the diameter of the fastener 1<SP>1</SP> so that the fastener 1<SP>1</SP> becomes fused to the sheet 3a but to the core 2b only of the sheet 2. During spinning, the body 1a<SP>1</SP> of the fastener 1<SP>1</SP> is held by the jaws of a quickrelease chuck. After joining, any protruding parts of the fastener(s) are ground flush with the upper surface of the sheet 3a. In another embodiment, Fig. 4 (not shown), a fastener (1) is urged axially into the body of a curved panel (2<SP>1</SP>) and may be left projecting from the body to leave a portion to which an article may later be connected. Specified thermoplastic materials are nylon, acrylonitrile - butadiene - styrene, polytetrafluoroethylene, acetal resins such as those made by polymerizing formaldehyde, polyvinyl chloride, polyethylene, polypropylene, polycarbonate resins such as those made by reacting bisphenol A and phosgene and acrylic resins such as polymethyl methacrylate esters and polymers or copolymers of acrylic acid, methacrylic acid, esters of these acids and acrylonitrile.