GB781560A - Improvements in machines for making hollow plastic articles - Google Patents

Abstract

781,560. Blow-moulding plastic bottles &c. GLENN PROPRIETARY, Ltd., L. & I. Nov. 18, 1954 [Dec. 24, 1953], No. 13281/56. Divided out of 780,439. Class 87(2). A machine for extruding a tubular length of plastic material and blowing it into bottle &c. shape is made by converting known injection-moulding machines of the type having a flxed platen 47, Fig. 2, a movable platen 46 and an injection cylinder 48 in which works a ram 55. The conversion involves removing the usual mould parts from the platens, removing the injection nozzle, fitting an extrusion-plus-blowing nozzle 56 to the cylinder and securing bottle mould halves Ma, Mb to the platens. Pressure pads 60 are secured to the platens to allow for the off-centre setting of Ma and Mb. In operation, ram 55 is moved to the left to extrude a tubular plastic length through nozzle head 56a, the extruded length being disposed between Ma and Mb. Then platen 46 is moved to the right by a hydraulic-plus-toggle arrangement to close Mb against Ma about the tubular length, the nozzle and cylinder being pushed back against the resistance of a spring 67a, and-guide pin 63 on the nozzle entering guide bush 64 on platen 46. Compressed air is then blown through the hollow nozzle core 56b to expand the length to bottle shape, platen 46 retracts to the left and ejector pins 57 carried by a spring-pressed plate 59 discharge the bottle from the mould. The nozzle 56 may feed two or more nozzle heads 56a, Fig. 3, the feed to each head being controlled by screws 74. Fig. 4 shows a modification in which the cylinder 48 and nozzle 56 are stationary, Ma being pivotally mounted at the lower ends of bell-crank levers 68 fulcrummed at 69 on stationary platen 47. The upper ends of levers 68 are adjustably connected to movable platen 46. As platen 46 moves to the right, Ma is moved to the left by the levers. Fig. 6 (plan) shows a modification in which Ma and Mb slide towards and from each other on rails 72, being moved by inclined dowels 73 which are fixed to movable platen 46 and enter slots in Ma and Mb. In a modification of Fig. 6, Figs. 7 and 8 (not shown) the machine is a vertical one, the movable platen rising to close the mould sections and the dowels extending upwardly therefrom. In a further modification, Fig. 9 (not shown), the machine is in general horizontal but the cylinder is vertically disposed. In other modifications (not illustrated) the moulds or nozzle heads may be moved by pneumatic or hydraulic cylinders.