GB287945A - Improvements in and relating to molding presses - Google Patents

Abstract

287,945. DemmÚ, R. A., and Davis, G. H. Oct. 4, 1926. Rotary-mould-table machines; moulds. - A press, particularly intended for bulk production of small articles from thermoplastic material, comprises a vertical main press and a vertical sub-press between which moulds are pressed intermittingly, the sub-press being associated with means for engaging and separating the parts of a mould. The invention is described as applied to the production of thermionic tube sockets from bakelite. A rotary table transports the moulds between the main and sub-press; the latter being equipped with means for inserting metallic terminals into the mould cavities, for charging the cavities with moulding-material and for applying a preliminary pressure, and also with means for forcibly separating the parts of a pressed mould and for ejecting the completed articles. The main press comprises a ram 4 carrying a head 8 which supports, through packing 16, a thermal jacket 15 co-operating with a similar jacket 17 carried by a fixed head 13. Pressure is applied to the ram through a valve 5 opened by a hand lever 6, the ram being returned by weighted levers 45 connected to the head 8 by rods 49. A rotary table 40, provided with one or more pairs of diametral openings to accommodate interchangeable moulds, is intermittently turned upon a pillar 213, Fig. 17, through half a revolution by ratchet mechanism 210 actuated through a cranked lever 204 and springs 206, 200 from one of the levers 45, Fig. 1. The table is arrested in correct position by a stop member 52 which is deflected by a lever 57 actuated by a member 56 on the head 8 to free the table for further rotation. To prevent actuation of the head 8 except when the table is properly positioned, the lever 6 is connected by a locking-rod 50 adapted to engage appropriate openings in the table. Each mould comprises a central chase member 150 having mould cavities, an upper force plate 152 furnished with dies and a lower member 151 adapted to support inserts upon pins. The parts 151, 152 frictionally engage the member 150 by dowels. At the sub-press station the member 151 is withdrawable laterally upon guide rails 170 and is replaceable by an ejector plate 158, Fig. 7, adapted to interengage therewith through claws 176, 177. The sub-press comprises an upper head 26, Fig. 1, hinged at 28 and adapted to be held down by a latch 33, and a lower member 22 adapted to be raised by cams 70, 71 thereon adapted to engage an abutment 74. A member 25 carried by a piston working in a cylinder 115 is adapted to engage the force-plate 152 and is also furnished with pivoted hooks 133 operable by a hand-lever 138 to engage the force-plate for its withdrawal from the mould. The cams 70, 71 are interconnected by gearing 72 and are turned to raise the head through a link 76 and lever 77 which is operable by a pedal or from the lever 45 through a link 95 disconnectible by a pedal 80 and link 97. The cams are turned to lower the head by a lever 87 operable through a chain 86 and pedal 81 or by the lever 45 through a rod 91. Pivoted members 101 controlled by a handlever 106 are furnished with latches 100 to engage the mould member and with recesses 107 adapted to engage pins on the pin plate 151. In operation, with an empty mould at the sub-press sta- .tion, a charged pin-plate is aligned with the mould and forced into engagement therewith by raising the head 22 ; the head 26 is raised and the moulds filled with powder by a charger 220, Fig. 15, having dowels 221 to engage the mould and comprising a container 226 having apertures 227 adapted to align with the mould cavities over which apertures an apertured slide 224 is vibrated by a handle 225; and the head 26 lowered and the force plate 152 forced into engagement with the mould to apply a preliminary pressure. The filled mould is then conveyed to the main press by rotation of the table. After pressing, the mould is brought again to the sub-press and the plates 152, 151 forcibly separated from the mould. The pin plate is then replaced by the ejector plate which is raised to eject the finished articles. During ejection, the mould plate is held down by stays pivoted to the head 25.