GB1108093A - Method and apparatus for producing molded articles of foamed plastics - Google Patents

Abstract

1,108,093. Moulding articles of foamed plastics. E. GONON. 31 March, 1965 [31 March, 1964], No. 13540/65. Heading B5A. In a process for moulding articles of foamed plastics, e.g. polystyrene the particulate material is fed in a stream of compressed air to the mould cavity which at the same time is connected to a source of vacuum, steam is then supplied to effect expansion after which cooling water is supplied, the mould is then opened and the article is ejected therefrom. The apparatus includes a two-part mould 101, Fig. 1, defining, when closed, a mould cavity 104 enclosed by chambers 102, 103 and connected thereto by apertures 105. The cavity defining mould walls are removably attached to plates P1, P2 fixed respectively to a movable upper and stationary lower platens 142, 141, Fig. 2. The upper platen 142 is connected to a pair of movable cylinders which co-operate with fixed piston rods to effect mould closing and opening. The platens are locked in closed position by a pneumatically operated latch (150, 151, Fig. 2a, not shown). The chambers 102, 103 have separate air, water, steam and vacuum connections and the mould cavity 104 is connected via pipe 106 and conduit 107 to the container 108 and via the pipe 106 and conduit 109 to a source of compressed air. A piston actuated valve 110 controls the outlet ends of the air and material conduits 109, 108. A valve actuated measured quantity supply device may be located in the feeding means. The programme control device comprises a rotary shaft 604 which is indexed by a pneumatically operated pawl and ratchet mechanism and which carries cam discs 605 each having axially displaced cam elements 606, 607 which co-operate respectively with the actuating rods 601 of fluid flow valves in the pneumatic control circuit and switches 611 of the electric control circuit. The operating sequence starts upon manual closure of a switch includes lowering of the upper platen to close the mould, the operating of the mould locking means and connecting the mould cavity to vacuum. The mould is then filled by blowing in the particulate material and steam is supplied to the lower chamber 103 until a predetermined pressure is reached whereupon steam is supplied to the chamber 102. After expansion of the material in the mould cavity cooling water is supplied to the chambers 102, 103. The mould chamber 102 is connected to the source of vacuum and the mould locking means is disengaged. The upper platen is now raised while compressed air is supplied to the chamber 103 so that the article remains in the upper mould half below which the pallet is then moved. Compressed air is then supplied to the chamber 102 to eject the article on to the pallet which is retracted.