Patent GB-940652-A (GB)
Title: Injection moulding machine
IPC: B29C45/06
Filed: 1960-07-18
Abstract: 940,652. Injection - moulding machines. UNITED STATES RUBBER CO. July 18, 1960 [Aug. 6, 1959], No. 24892/60. Heading B5A. [Also in Division F2] A single or duplex rotary-table injection moulding machine has mould wheels 46, 47 carried by a hollow shaft 45 which is rotated to bring one of several two or three-part 54, 55, 56 moulds clamped by toggles 121, 118, 109 and springs 108, 114 opposite an injection cylinder 148. The filled mould is advanced to a curing region during which the inlet end of the sprue is plugged to prevent the material from expanding out of the mould and leaving cavities in the moulded article. After curing, the articles are removed at G, and the sprue removed by a drill 278. Injection.-A piston-rod 209,Fig. 2, is actuated to move a rod of moulding material to the right into a housing, a cylinder 200 is then actuated to cause a blade 202 to sever a blank from the rod which falls into a pocket 206 in a wheel 205. The piston-rod 209 is moved to the left causing the gripping members 213 to be drawn out of the rod and slid back over it. The cylinder 200 is actuated in the reverse direction to raise the blade 202 and at the same time rotate the wheel 205 and empty a previously filled pocket into a shoot 160, where the blank falls on to the fingers 186 of an upper slide 185. When the injection piston 147 is retracted a pin 162 causes movement of the slide 185 and a lower slide 186 having fingers 171 in such a manner that a single blank falls on to a support 158 from which it is moved into the injectioncylinder 148 with the next stroke of the injection piston, and at the same time the slide 185 is retracted to allow the next blank to fall on to the fingers 171. Operation of the slides only takes place if the injection-piston is advanced beyond a predetermined point in the cylinder. The cylinder is movable away from the moulds by springs 155, and is moved back with the piston. Mould opening and closing.-Assuming the mould parts to be clamped together, a cam roller 126 moving in a channel 39 causes a bell-crank lever 124 to move a toggle 121 so that it moves a yoke 109 from right to left. This moves lower and upper rods 83, 84 to the left, causing the plate 79, which carries the mould past 54, to move away from the plate 77. After the rods 83, 84 have moved the plate 79 through a distance sufficient to extract the sprue 54 from the confines of the mould past 55, the shoulders 83b and 92 on the rods 83, 84 respectively engage the plate 77 to move the mould part 55 away from the part 53. At the same time a projection 98 enters a curved part of a cam groove 97 in the rod 84, so that the rod 84 is rotated causing the head 96 to be brought into alignment with a slot in the plate 79, and movement of a rack 136 with the rod 83 is prevented by a stop 140, and the plate 79 is pivoted outwardly by the pinion 130 until it is horizontal (see Fig. 5, not shown). Further movement of the plate 77 is prevented by fingers 73. When the cam roller 126 is returned to its normal position, the operation is reversed to close the mould parts, and clamp them together by the springs 108, 114. Backrinding.-During curing, a rack 231, Fig. 3, is moved downwardly to rotate a pinion 219, swing an arm 216 and bring a plug 217 into alignment with the sprue. This movement also causes, through a pin 229 acting in a cam groove allowing a spring 225 to move a rod 215, the plug 217 to move into the sprue entrance. The movement of the rod 215 is reversed before the mould parts open to remove the plug 217. Article extraction.-A projection 267, Fig. 4, in a cam groove 263 swings an arm 269, bringing a nozzle 270 into alignment with the mould, further movement of a sleeve 262 causes a bushing 272 to engage the article 259, and suction is applied through a pipe 274. The sleeve 262 is then moved in the opposite direction to draw the article out of the mould cavity. When the article is clear of the mould cavity, the arm 269 is again swung, the suction stopped, and the article allowed to fall on to a conveyer. Mould heating.-Steam is fed through pipes 59, 61, 62, 63 to channels 57 in the mould ring 52 and through passages 41 in the shield 30 for the mould wheel. A modified arrangement for steam heating the mould is described with reference to Fig. 14 (not shown). In a further modification (Fig. 15, not shown), the moulds are heated electrically by current supplied by brushes which rotate around a fixed ring surrounding the hub of the mould wheel. Modifications.-The mould wheels may rotate about a vertical axis. The mould may comprise two plates (Fig. 11, not shown). A clutch (Figs. 12 to 14, not shown) may be provided in the drive to the wheels) to allow one or other or both the wheels to be rotated. The springs which keep the mould parts clamped may be replaced by an hydraulic device (see Figs. 17 and 18, not shown). The moulding material may be fed by rollers instead of by the gripping device. The articles may be ejected by pins.