Patent GB-515790-A (GB)
Title: Improvements in or relating to moulding presses
IPC: B30B11/00
Filed: 1938-06-03
Abstract: 515,790. Hoppers. MOLDED INSULATION CO. June 3, 1938, No. 16682. Convention date, June 5, 1937. [Class 78 (i)] [Also in Groups V and XXXVII] Relates to an electrically-operated mechanical press for moulding heat-hardenable powders in which all the steps of the moulding operation are controlled by a timing-device adapted to actuate switches. The upper platen 12a, Fig. 2, of the press is. heated and is mounted on a screwed plunger 15 carrying a nut adapted to be rotated in either direction by a worm 19 driven by an electric motor. The upper platen has a stamp 12 adapted to enter a lower heated platen 11 that is carried by a frame 32 having rods 30 normally held in the raised position by springs 25. In operation, when the upper platen is lowered, the lower platen is also moved downwardly, and when a predetermined pressure is attained as determined by the compression of the springs 25, a switch 33 is opened to cut-out the motor driving the worm 19. When the worm is driven in the reverse direction, the platens rise, the punch 12 is removed from the lower platen, and a frame 34 is moved upwardly by springs to force pins 36- through the lower platen to 'detach the article. At the same time,. an air blast cleans the mould and a lever is turned to eject the article into a receiver 56. The article falls on a pivoted switch at the bottom of the receiver and ensures the further operation of the machine as determined by the timing-device. When the frame 34 rises, a rack 44 formed on one of its sides operates a pinion 43 of a device for supplying powder from a hopper to a shoot leading the moulding-powder to the lower mould member. The pinion drives a tubular member 38, Fig. 4, having an opening 38b and relatively adjustable vanes 41a, 40a determining the size of a pocket filled from a hopper 42. The member 38 is rotated in the direction of the arrow beyond the position shown to avoid compacting of the material in the pocket. When the previously made article has been removed from the mould, the member 38 is rotated in the reverse direction and discharges its contents through the shoot 42a into the lower mould. The upper platen then descends, and, after preliminary compression of the material, rises to allow escape of gases, an air blast being used to remove any powder ;on the top of the lower mould. The platen 12 is again lowered to apply pressure which is maintained until the article is cured. Actuation of switches; control of electric motors.-The starting, stopping, and reversing of the motor 20, shown diagramatically in Fig. 7, for operating the press, and the supply of compressed air for cleaning the mould are controlfed by a timing-device comprising a number of mercury switches 92, each controlled by a pair of spring-controlled rods 70, 71 having adjustable projections 70b, 70a &c. adapted to be engaged by a bar 86. The bar is carried on chains 87, 88 driven through reduction gearing from a constant-speed motor 89. The positions of the projections determine the times of the changes of operation of the press. The time that the bar 86 is on the distant runs of the chains corresponds to the time of curing of the article in the mould. When the driving motor 20 has lowered the press platen through a predetermined distance, a switch 33 operated by the press member cuts off the supply of current to that member. Specifications 515,828, [Group XXXVII]; and 515,829, [Group V], are referred to.