GB864179A - Injection moulding machine - Google Patents

Abstract

864,179. Injection-moulding machines. FEMCO MOULDING MACHINE CO. Ltd. Jan. 13, 1960 [Jan. 19, 1959], No. 1881/59. Class 87(2). An injection-moulding machine, of the type having a fixed injection head for injecting plastic material into moulds as they are successively indexed on a rotary table below the head, comprises a camshaft adjacent to and having a part directly engaging the outer edge of the table, which camshaft controls in timed relationship the table-indexing mechanism, the feeding assembly for the injection head, means for locking the indexed moulds, and the means for injecting the material from the head into the mould at the injection station. A rotatable table comprises spaced circular plates 10, 11 each having a ring of apertures which in plate 10 support the upper mould parts 12 and in plate 11 allow the passage of plungers 8 which carry the lower mould parts 13. The table is intermittently rotated by the driving arm 27 of a Geneva mechanism 26 carried on a main vertical shaft 28 driven by motor 6; which arm carries a roller which engages slots in plate 11, Fig. 2 (not shown), and recesses between each slot are successively engaged by a lobe 30 of said mechanism to ensure accurate mould positioning. Plastic material is fed to pre-plasticising unit 92 containing a heated torpedo 96 and from thence to the injection cylinder by a plunger 108 connected via yieldable transmission to a shaft 118 reciprocated from crank 111 on shaft 28 via rods 112, 114, rack 115, shaft 116 and rack 117. A plate 124 attached to plunger 108 operates an adjustable metering pusher 126 which feeds forward granular material from hopper 103. At each station the plunger 8 is forced upwardly to lock the mould against the injection nozzle 49 by a toggle mechanism 83 which is straightened via link 85 and arm 84 under the action of cam 88 on shaft 28 and later collapsed by a further cam 86 on this shaft. Cam 79 on shaft 28 actuates microswitch 80 to energise the solenoid of valve 71 which allows the passage of oil through pipe 72 to the top of piston 44 in cylinder 42 and thus causes the injection stroke of plunger 45. Figs. 5 and 6 (not shown), illustrate a threaded cap member 139 produced by the apparatus between the two part members 12 and a core in member 13 which core is rotatable to release the article ; the broken sprue being blown away by an air jet. Rollers 136 running on track 137 and attached on arms to the bottom of plungers 8 control the opening and closing of the moulds, and the stripping of the article 139 is controlled by a roller 146 in a cam groove 147 in a block 148 keyed to the shaft 28.