GB839015A - Improvements in or relating to injection moulding apparatus - Google Patents

Abstract

839,015. Injection moulding machines. PROJECTILE & ENGINEERING CO. Ltd. March 6, 1958 [March 6, 1957], No. 7476/57. Class 87(2). Plastic material is fed continuously so as to fill a series of injection pots 27, Fig. 1 seriatim, each injection pot having a ram 28 and communicating with a mould 32, 33, and the rams are operated in turn to effect injection after the pot has been filled and while it is cut off by a valve from a feeding device. In Fig. 1 the material is fed from a hopper 16 by a screw 13 and through a port 18 in a fixed sleeve 17. A distributor head 19 is rotated by a gear 21 to bring a series of radial ports 23 having nozzles 26 into line with the port 18 to fill the pots 27. The rams 28 are operable by a . fixed cam 29, and a strong spring 28b, allows limited yielding of the ram head 28a. Opening and closing of the mould part 33 is effected by a cam ring 36 and rollers 38, 39. The mould parts 32, 33 are held closed by hooks 47 engaged by rollers 46 on links 45, release being effected by a lug 48 on a lever 40 which is pivoted at 41 and actuated by an annular cam groove 43. A spring plunger 50 enables moulds of different capacity to be used simultaneously by storing excess material delivered by the screw 13. In a modification, Fig. 3, the pots 57 and injection rams 61 are arranged radially, the rams 61 being annular and actuated by bell-crank levers 64, 65, rollers 67 and a cam 68. In a further modification, Fig. 4, a ball valve 70 prevents transmission of injection pressure back to the sleeve 17. The ball valve is arranged in a sleeve 59 and has a stem adapted to enter and obturate the nozzle 26.