Patent GB-681066-A (GB)
Title: Improvements in or relating to apparatus for molding and vulcanizing hollow rubber articles
Filed: 1951-02-22
Abstract: 681,066. Moulding hollow rubber articles. GENERAL TIRE & RUBBER CO. Feb. 22, 1951 [Feb. 25, 1950], No. 4336/51. Class 87 (ii). Apparatus for moulding hollow rubber articles, particularly large ones such as washing machine tubs, comprises two relatively movable supports, spaced mould sections on each support arranged to form cavities to mould the outside of the articles, a bar to fit between the mould sections, cores attached to the bar and projecting in opposite directions therefrom, and a support for the bar movable when the mould sections are separated to carry the bar and cores from moulding position to stripping position. The supports comprise a top platen 3 mounted at the top of standard 2 and a bottom platen 4 guided by the standards and movable by a hydraulic ram and cylinder 5, 6. The top mould sections 26 are attached to the under side of the platen 3 and the bottom mould sections 28 are attached to the bottom platen 4 in vertical alignment with the top mould sections. When the mould sections are brought together their cavities 30 form the moulds for the outside of the articles, and they are shaped so that positioning surfaces 31, 32 are at opposite ends of the cavities (Fig. 7). The bar 12 is carried by chains 10 from trolleys 8 mounted on a track formed by an |-beam 7 which extends horizontally across the top of the press. The trolleys 8 are'connected by a bar 9, with which they form a travelling carriage, Fig. 4; and a chain 48 whose ends are fixed to opposite ends of the carriage is guided under a sprocket 50, whereby, when the sprocket is rotated by an electric motor 52, the carriage moves along, the track between stops 54, 55. The cores consist of members 15 clamped to the bar 12 by a clamping member 14 and positioned by grooves 18, 19 therein which receive a circumferential rib 17 on the core member 15. An axial tube 22 stiffens the core, fitting in extensions 21, at its ends and held by cylindrical nuts 23 of the same outside diameter as the extensions 21, the surfaces 32 being designed to fit over both. With the mould open and the cores in the stripping position, Fig. 1, pieces of sheeted unvulcanized rubber are placed in the cavities of the bottom mould sections 28 and on the cores 15. The carriage 8, 9 is then moved until it comes against the stop 54, when the cores are in vertical alignment with the mould cavities (the dotted-line position in Fig. 1). The ram 5 is operated to raise the bottom platen 4, during the upward movement of which the surfaces 31 of the bottom mould sections come into engagement with recesses 16 in the cores and the surfaces 32 with the extensions 21, while the bottom mould section 21 come one on each side of the clamping section 14, assisted by a taper 35 thereon, and the cores move upwards with the bottom mould sections, this movement being permitted by the fact that the chains 10 terminate in rods 11 on which the bar 12 can slide. As the mould is closed the rubber is compressed and fills the cavities, and the moulded articles are then vulcanized. The platen 4 is then lowered, allowing the core carrying bar 12 to slide down the rods 11 until it comes against nuts 13, after which the lower mould sections 28 move away from the cores, freeing them so that the carriage 8, 9 can move to the position shown in full lines in Fig. 1, i.e. the stripping position where the moulded and vulcanized articles are removed from the cores. Heat for vulcanization is imparted to the moulds by supplying steam through inlets 40 to chambers 36, 37, 38, and the cores are heated by supplying steam through an inlet pipe 42 that extends vertically through the carrier bar 12 and branches out at 43. Condensate is drained from the moulds through connections 41 and from the core through tubes 45. To prevent escape of steam the open ends of the tubes 45 are positioned in pockets 46 and have notched ends to facilitate flow of water into them, the steam pressure forcing the condensate through the tubes 45 to the outlet 44.