GB1075801A - Improvements in or relating to methods of moulding plastics and to apparatus for carrying such methods into effect - Google Patents

Abstract

1,075,801. Injection moulding machines. INVENTIONS FINANCE CORPORATION. Dec. 12, 1963 [Dec. 22, 1962; May 15, 1963], No. 23474/63. Heading B5A. In an injection moulding machine plasticized material is continuously supplied by a worm 64 to a transfer chamber 60 and thence through a piston 174 incorporating non-return valve means 166 into an injection chamber 61, a piston 126 at the rear end of the chamber 60 being movable relatively to, the, piston 174 in dependence on changes in the volume of plastic material in the chambers 60, 61. The piston 126 is, biased to the left by fluid pressure in a chamber 150 acting through rods. 156. A piston member 134 in chamber 150 moves a piston rod 128 and the piston 174 to the left to effect injection through a nozzle 68. The non- return valve means comprises a circular series of tapered openings 180 in the piston member 174 which is slidable on the, piston rod 128 between a flange 166 and nut 168. When the piston 126 is in its extreme left hand position shown in Fig. 4, flow of material to the chamber 60 continues: through registering grooves 182, 184 in the piston 126 and injection cylinder 62 respectively A slidable closure member 82 in the nozzle, housing 72 has enlargements 84, 86 for blocking nozzle orifices 70, 76 respectively The closure member- 82 is movable. by a bell crank lever 96 pivoted at 98 and engageable by pistons: 112, 114. To open the injection orifice 70 the fluid pressure acting in the chamber 150 is transmitted to an adjustable regulator device 110 and withdraws, the piston 114 against the action of a spring (124) (Fig. 9, not. shown). When the. mould is full, back pressure on the valve member 82 causes closing- of the orifice 76 by the enlargement 86. Dogs 158, 160 carried by the piston 126 and piston rod 128 engage contacts 159, (164), 164A of a control circuit (not shown) for the machine. The injection section of the machine is slidable on rods (H) (Figs. 1, 2, not shown) towards and away from the mould (12) by means of a hydraulic jack (34) (Fig. 12, not shown). A hydraulic cylinder (14) and piston (16) open and close one of the mould sections. The mould (12). is held closed by high pressure hydraulic units (8) variable in position by means of screws (6). Modifications.-Instead of using a jack (34) the injection section of the machine may be moved towards the mould by introducing fluid into a cylinder (200) (Fig. 15, not shown) mounted on the injection section and having a piston (202) threadedly mounted in a fixed support (206). In Fig. 13 (not shown) an adjustable coupling (240) is provided for one of the mould platens (81<SP>1</SP>). In Fig. 15 (not shown) instead of using switches to control the piston (126<SP>1</SP>) the rearward travel of this piston (126<SP>1</SP>) is limited by a pivoted arm (256) adjustable in position by means of a threaded shaft (266) and tube (258). Figs. 17 to 19 (not shown) illustrate a simplified regulator device for controlling flow through the injection nozzle, the two piston rods (316, 319) acting on the pivoted bell crank lever (100<SP>1</SP>) being arranged concentrically. Figs. 16 and 20 (not shown) show hydraulic systems for controlling the machine shown in Fig. 13.