GB784168A - Method and apparatus for the production of rubber boots - Google Patents

Abstract

784,168. Molding rubber footwear. SOC. DES CAOUTCHOUCS DE LIANCOURT. April 18, 1955, No. 11110/55. Class 87(2). A multiple core and outer mould sections are used in the production of rubber boots by a method in which the core parts are arranged so as to reduce its thickness, a lining is placed over the core, the parts of the core are slid together to stretch the lining, the stretched lining is coated with a sheet of unvulcanized rubber, the lined core is turned to a vertical position and the mould sections are applied against the core. A three-part core, Fig. 2, comprises a central part 30 with inclined faces 28, 29 on which outer parts 26, 27 slide. The parts 26, 27 between them approximate to the shape intended for the leg and upper portions of the boot. In the Fig. 2 position the core is contracted in width and a pre-formed sock of suitable, e.g. textile, material is pulled over the core. The core and mould parts are of metal and are pre-heated. Unvulcanized rubber is spread on the material covering the core, the heat of which causes it to cling to the sock and conform to the shape of the core. The core parts 26, 27 are then pushed along the inclines 28, 29 until they meet the face 38 of the core, which is pivotally mounted at 25. Ball or roller bearings may assist the sliding. The core is then swung to a vertical position and is enclosed between the two halves of the mould, one of which is shown in Fig. 1. There may be linkage whereby this swinging movement causes the sliding of the parts 26, 27 on the central core part 30. A third mould part 22, shaped to mould the sole of the boot, enters the top of the mould. The core is centred by the base 38 being a close fit in the space formed between the cavities 13 of the mould halves. The assembly is placed in a hydraulic or other press, one platen of which is shown at 15 (16 indicates heating elements) and the part 22 being operable by any suitable pressure means, and the rubber is vulcanized under heat and pressure. The composite construction of the mould and core makes removal of the moulded boot very easy. The interposition of springs between the core parts 26, 27 and the base 38 enables the core to be put in the mould not quite laterally expanded, and force is then applied to the base to produce internal mould pressure. Instead of the sole being moulded by a part 22 to which pressure is separately applied, a member 34 with inclined faces 36, 37 engaging inclines 32, 33 in the mould parts A, B, Fig. 4, may be used. Fig. 4 also shows a rib 39 on the core which engages with a groove 40 in the mould halves to ensure accurate positioning.