GB1095474A - - Google Patents

Abstract

1,095,474. Injection moulding rubber articles. DUNLOP CO. Ltd. Sept. 18, 1964 [Oct. 5, 1963], No. 39312/63. Heading B5A. Articles of rubber or like elastomeric material are made by (i) injecting rubber &c. into a mould 60, 61 (Fig. 1), (ii) moving the mould and injection apparatus 1 apart in a direction parallel to the plane of their engaging surfaces so as to shear the rubber &c. in the mould inlets 63, (iii) removing the articles from the mould, and (iv) removing the rubber &c. from the inlets 63 by applying fluid pressure thereto. Mould filling.-The mould 60, 61 is moved into contact with the injection cylinder 1a by an hydraulic ram 9, operation of a limit switch 15 starting an injection screw 7. When the mould is full the pressure produced by the screw moves the mould downwardly through 0À005 inch thereby operating the switch 15 to stop the screw 7 and start a timer. The ram 9 then raises the mould again to ensure full closure thereof. The timer then causes the mould to be lowered again. When the mould has moved 0À04 inch a switch 16 is operated and downward movement is stopped. The injection apparatus 1 is as described in Specification 1,090,408. Sprue shearing.-Operation of switch 16 also energizes a pneumatic cylinder and piston 11, 13 to move the mould laterally on to a plate 14, thereby shearing the rubber in the inlets 63 level with the top surface of the mould. Article removal.-After vulcanizing in a vulcanizing press (not shown) the mould is placed on a plate 19 (Fig. 4). A piston and cylinder assembly 22 is actuated to raise a platen 23 carrying rods 25. The rods 25 pass through holes 76 in the bottom mould part 61 and are received in recesses 77 in the top mould part 60 which is thereby lifted to the dotted line position in Fig. 4. A block 27 carried by the platen 23 passes through an opening 28 in the plate 19 and raises a plate 67 carrying ejector pins 68. The moulded plugs 74 are thereby ejected from the mould cavities and are subsequently removed by a brush 29 moved across the upper face of the lower mould part 61. Sprue. removal.-The upper mould part 60 is moved from the dotted line position shown in Fig. 4 to a sprue removal station by means of a carriage 31 slidable on guides 40 by pneumatic cylinder and piston assemblies 37, 39. The mould part 60 is then raised by an hydraulic piston 41 and the rubber " pips " 75 in the mould inlets 63 are removed by intermittent blasts. of compressed air. This air is introduced by a pipe 45 into a chamber formed by the mould part 60, a seal 44 and a plate member 32 carried by the piston 41. A restrictor plate 48 spaced slightly from the upper surface of the mould part 60 is removed when the " pips " have all been loosened to allow the loosened " pips " to be blown away.