GB581642A - A method of and apparatus for injection moulding of plastic materials - Google Patents

Abstract

581,642. Injection-moulding machines. MILES, H. G. W. CHICHESTER-. Dec. 11, 1944, No. 18743/43. [Class 87 (ii)] The moulds are pulled around an endless track A, Figs. 1 and 2, by a chain 16 which has teeth which engage racks 60, Fig. 10, on the mould bases. The chain moves intermittently, counterclockwise, and during the periods of rest the following operations are performed:- At B the hinged sections of an empty mould are locked together, and the mould is filled with rubber or thermo-plastic or thermosetting resin through, e.g., a central orifice in the upper section; at C the filled mould passes through an oven, e.g., a vulcanizing chamber; at D the mould sections are unlocked and the upper section is raised into the vertical position, the moulded article usually adhering to the upper section; at E a suction device removes the article from the upper section; at F a similar suction device explores the lower section and, if the article has remained therein, removes it therefrom: at G and H rotating brushes clean the mould section cavities; and at J an oven preheats the mould before it is filled at B. The track A comprises rollers 14. Each mould comprises lower and upper sections 41, 42, hinged at 57, the upper section having an extension 58 which is engaged by a fixed cam 73 at station D to raise the upper section; a cover plate may close the filling passages. The mould-locking device comprises an eccentric 49 fixed on a short shaft 47 journalled in a bearing 45 on the mound base; the shaft and eccentric are turned by means of a rocker 48, and as the eccentric turns it moves horizontally a catch block 51 having wedges 53 which, in the locking position, engage wedges 55 on the upper mould section. The mould-filling and -locking station B comprises an injection cylinder 23 mounted on a plate 22 carried by rods 21 pivoted on levers 19 fulcrummed on links 20 supported by a fixed platform P. The rods 21 are connected by members 26 to a vertically-sliding plate 24 which carries a spring-loaded finger 28. When the assembly 19-28 is depressed by means of a pneumatic cylinder 18, the plate 24 exerts great closing pressure on the mould, the finger 28 turns the rocker 48 to lock the mould, and the cylinder nose 29 enters the mould orifice. The injection plunger 32 is carried by a verticallysliding plate 31 operated by pneumatic cylinders 30, and is fed with single pellets of moulding material from a hopper, the pellets passing through an infra-red oven into a feeding duct. Station D comprises a bar 64, Fig. 6, carrying spring urged plungers 65 and a rod 66; when the bar 64 descends, plungers 65 hold the mould still whilst rod 66 turns rocker 48 to unlock the mould. Station E comprises a suction bell 84 carried by a shaft 81, the bell being swung from the dotted-line position, Fig. 2, to the full-line position, pressed into contact with the article, retracted, and swung back to the dotted-line position. Station F may comprise an identical vertically-disposed device or a slightly modified horizontal device. The machine may be modified; thus, the track may comprise several continuously-moving conveyers, stationary collecting sections and mould pushing devices.