GB605677A - Injection moulding machine - Google Patents

Abstract

605,677. Hydraulic presses. HERBERT, Ltd., A., BEBB, R. H., and JONES, L. N. Jan. 3, 1946, No. 235. [Class 69(ii)] [Also in Group V] The heater cylinder 20 is filled with moulding material in known manner, and compressed air is then admitted into a pipe 28 thus causing pistons 14 to lift the lower die-holder 15 into contact with the upper die-holder 38 and raise it, together with the cylinder 20 and injection plunger 17 which fits in the cylinder and rests on the material therein. Plunger 17 is fast with an abutment 39 and as 39 rises against springs 102 it opens valve 21, the plunger and abutment being then restrained from further movement. At the same time, a safety valve 36 is opened by a finger 40 so that compressed air is admitted into the right-hand side of an intensifier cylinder 37, whereupon liquid in the cylinder 44 is caused to apply high pressure to rams 12, 18, 18. The area of the ram 12 is greater than the total area of the rams 18 so that a high mould-closing pressure is applied and at the same time the cylinder 20 is forced upwards over the plunger 17 and the plastie material is injected into the mould. The operation is reversed by opening pipe 28 to exhaust and pipes 33, 49 to pressure. The moulding cycle may be repeated automatically, the pneumatic valves being operated by solenoids controlled by limit switches 46, 51, which are operated by fingers 47, 50. The liquid in the cylinder 44 is replenished during the mould closing stroke through a pipe 53 which leads to a reservoir, a valve permitting oil to flow from the reservoir, the valve being opened, to allow oil to return to the reservoir, during the mould opening stroke, by air pressure in the pipe 33.