Patent GB-802713-A (GB)
Title: Improvements in or relating to the manufacture of hollow fibrous reinforced synthetic plastic articles
IPC: B29C53/50
Filed: 1956-11-29
Abstract: 802,713. Moulding reinforced resin pipes. PLYM, O. V. Nov. 29, 1956 [Nov. 29, 1955], No. 36551/56. Class 87(2). [Also in Groups X and XXVIII] In a method of making hollow articles of fibrousreinforced synthetic plastic, particularly glass-fibre reinforced plastics, a fibrous web 7 is applied to a flexible carrier 6 and impregnated with a liquid plastic material, after which an inflatable bag or hose 9 of soft material is applied to the web and the longitudinal edges of the carrier are brought close together to cause the carrier and the web to encircle the hose. The latter is inflated to press the web against the, carrier and cause the plastic material to penetrate through the web and form a tube reinforced with fibrous material. The plastic material is cured. As shown in Fig. 1, a carrier 6 of paper, acetate or viscose film, impregnated fabric, sheet metal or synthetic resin, is attached to bars 4 pivoted on curved arms 1 pivotally mounted on a support 3 ; alternatively, the bars are arranged to slide towards and away from each other. A woven glass or other fibre mat 7, or fabric, is placed upon the carrier and a quantity of synthetic resin 8, preferably a resin of the ester type including an accelerator and a peroxide catalyst, is poured on to the mat, a rubber hose 9 then being applied to the mould constituted by the carrier. The bars are brought together and the hose is inflated by compressed air or pressure liquid to press outwardly the resin 8 which penetrates the mat, air and excess resin escaping through a small opening 10 between the bars. After the resin has solidified at room temperature or is cured by the application of heat, the hose 9 is deflated and withdrawn from or left within the finished tube. Alternatively, the mat is impregnated prior to the placing thereof on the carrier or by introducing resin through ducts or openings from the outer side of the mat after the hose has been positioned and the edges of the carrier brought together. A layer of paper may be applied to the carrier and remain on the finished tube. The tubes may be cylindrical or conical with a rectilinear or curved generatrix. A machine for continuously making tubes and shown in Fig. 3 comprises an endless belt 11 provided with ribs 12 and carried by rollers 13, 14 one of which may be power driven ; guides 15 fold the belt to form a mould and to bring together the ribs. A web 19 of cellulose acetate or viscose film is interposed between the belt and the mat 7, and the hose 9 is produced continuously from a web 16, of synthetic resin, the longitudinal edges of which are welded or glued together by means of a roller 17 and a guide 18 and, if necessary, by the use of heat. Resin is supplied through a pipe 21 and between the mat and the belt or the web 19, and an air pipe 20 projecting into the hose has a rubber extension 26, Fig. 5, which is forced by the compressed air against the wall of the hose to prevent leakage of air. The outer face of the belt may be subjected to vacuum to facilitate penetration of the resin through the mat 7.