GB815625A - Improvements in or relating to molding apparatus - Google Patents

Abstract

815,625. Compression-moulding powdered plastic materials. ALESI, J. A. Sept. 10, 1956, No. 27631/56. Class 87(2). A die carrier D is reciprocated vertically by a pneumatic cylinder 12, the movement from the piston rod 12<SP>1</SP> being transmitted through force transfer links 14, 15, Fig. 5. The feeding mechanism is mechanically actuated from the movement of the upper die carrier D by the interaction of cam slots 72, in vertical plates 74 fixed to the die carrier Figs. 2 and 3, with cam wheels 70 carried on shafts which are also the shafts for rollers 44 and are mounted at the front of a feed tray F. The feed tray F, which comprises upper and lower plates 46, 54, is reciprocable beneath a hopper and is guided by channels 38, 40 in which the feed tray rollers 44 run. The channels are connected at the rear by a crosspiece 42. Tubes 50 are arranged in a transverse row in the feed tray and, when the tray is retracted beneath the hopper, Fig. 2, are open at the top to the material in the hopper but are closed at the bottom by a loading plate 56, which is slidable underneath the lower plate 54, being connected thereto by posts 58 which pass through slots 60 in the loading plate. The operation of compressed air valves is electrically controlled by a switching box 100. Air is admitted to the top of the cylinder 12 and the die carrier D descends, the cam slots 72 drawing the feed tray F towards the mould carrier C till, in the Fig. 3 position, the tubes 50 are over the mould cavities 10. A bumper 64 on a trip bar 62 which extends back from the loading plate 56 meets the crosspiece 42 and the forward movement of the loading plate is arrested, the remaining travel of the feed tray thus uncovering the bottom of the tubes 50 when they are over the mould cavities and allowing a measured quantity of the material 68 to flow into them. Ejector pins 84 depend from a bar 90 and pass through the dies 82. The bar 90 is biased downwards by springs 94, which cause the pins 84 to eject those moulded articles which stick to the die as the carrier D rises. An inclined plate E is pivoted at 75 to the feed tray F and is tilted upwards, from the dotted to the full line position, Fig. 3, by projections 77 from the cam plate 74 as the carrier D rises, so that the plate E firees any articles still sticking to the moulds. The plate also acts as a shoot to deflect the articles into a receptacle in front of the machine. The beginnings of the up and down movements of the die carrier are controlled by triggers 110, 108 on a vertical bar 112 which actuate a limit switch 106 carried by the mould carrier. When, on the downward movement of the die carrier D, the dies reach a position just above the moulds, the reciprocating movement will stop unless the switch 106 is actuated by the trigger 110, which will not happen if a moulded article has remained in the mould cavity. Damage due to a fresh charge being pressed against a stuck moulded article is thus obviated. The mould carrier C and die carrier D are electrically heated.