GB853386A - Improvements in or relating to fibre glass moulding - Google Patents

Abstract

853,386. Moulding pre-stressed fibre-resin articles. EDEY, C. C. A. Nov. 21, 1958 [Aug. 21, 1957], No. 24828/67. Class 87(2). To form a pre-stressed fibre reinforced article glass fibre rovings 10 are wound on a rotatable former 11 which may be treated with a release agent, e.g. carnauba wax, and rovings 13 are laid in slots 12, the two rovings being cemented together by, e.g. polymethyl methacrylate dissolved in xylene. After the rovings are removed from the former, a mat 14 of chopped glass fibres, is inserted between the rovings, and similar strips 15 are interwoven on the outside. The ends of the assembly are impregnated with epoxy resin, the whole rolled up to the form shown in Fig. 4, and the ends enclosed in " Cellophane " (Registered Trade Mark). Connectors comprising internally and externally threaded members having screw-threaded plugs 20 are placed over each end. Each connector is made up from two parts connected by dowels and a locking device. Polytetrafluoroethylene washers 22 may be placed over each end of the roll before assembly, and the connectors may be coated with a release agent comprising a baked-on silicone solution covered with carnauba wax or sodium alginate. The epoxy resin in the ends is then cured and the assembly is placed in a tensioning frame where nuts 27 are screwed up to stretch the roll. Whilst in this stretched state, a mould is positioned around the roll between the washers 22, the mould surface is treated with a release agent, and a polyester resin is forced into the mould. The roll may be first thoroughly wetted with resin, and air may be sucked out of the mould. After curing, the mould is removed, the roll reinforced with an outer layer of rovings and cold setting resin, and after complete curing, the connectors removed. The roll may be formed with end flanges to retain polytetrafluorethylene collars, and the pressure of the impregnating resin used to produce the stretching for the pre-stressing. The collars are coated with an accelerator to prevent leakage of resin.