GB1529754A - Injection blow moulding apparatus - Google Patents

Abstract

1529754 Injection blow-moulding FARREL PLASTIC MACHINERY CORP 26 Jan 1976 2971/76 Heading B5A In an injection blow-moulding device, an injected parison 26 is supported by a blow/ injection core 16<SP>1</SP> projecting from one end into a split blow mould 28, 29. Projecting into the mould from the opposite end is a tube 38 which at the beginning of the blowing operation telescopes with a small clearance over the parison. During the initial phase of the blowing operation expansion of the parison is restricted by the tube to be longitudinal. During a subsequent phase of the operation the tube is gradually withdrawn so that the longitudinally expanded parison can progressively radially expand into contact with the mould (see Fig. 5). Alternatively, the tube can be withdrawn after longitudinal expansion and the radial expansion effected. A cushion of air, perhaps assisted by pressurized air directed radially inward through the tube wall, prevents frictional contact of the parison and the tube. The tube 38 is slidable over a rod 40, the position of 'which may be fixed or which may be longitudinally movable by a piston and cylinder mechanism 43, 44, and is actuated by a piston and cylinder drive 64 through a rod 66 and a collar 62 attached to the rear end of the tube. Movement of the tube in phase with the blowing is ensured by a valve 68 controlled in accordance with the blowing air. In one mode of operation of the device, the rod is fixed with its free end flush with the mould wall whilst in another mode the rod starts with its free end adjacent the parison and during the blowing is withdrawn until a collar 52 on its rear end engages a stop 46 carried by the piston and cylinder device 53, 44, at which point the free end of the rod is flush with the mould wall.