GB828164A - Improvements in and relating to presses - Google Patents

Abstract

828,164. Compression-moulding of finelydivided materials. COAL INDUSTRY (PATENTS) Ltd. Sept. 3, 1957 [Sept. 4, 1956], No. 26995/56. Class 87(2). A multiple plunger assembly in a coal-briquetting press comprises an inner plunger 6 and outer annular plunger 5, in which part of the inner plunger fits, and a fluid-filled chamber 31 in which pressure is generated by the reaction, when compressed by the outer plunger 5, of the fine coal or other powder intended to form the briquette, the inner plunger 6 being movably arranged in a plunger guide body 2. Screwed to this body 2 is a ram attachment piece 3 which is connected to the main press ram 25 and which has formed within it a chamber 27. Secured to the outer plunger 5 is a cylinder 1 arranged for movement on the guide body 2 and there is an annular extension from the guide body 2 into the base of the cylinder 1, the top of the inner plunger 6 entering this extension with its head hard up against the guide body. The chamber 31 is formed between the outside of this extension and the inside of the cylinder 1. To the bottom of the plunger 6 an end piece 7 is attached and from its top a plunger 32 extends, on which is an ejection piston 8 movable in the chamber 27. When the ram 25 descends the outer plunger 5 and the inner plunger and end piece 7 are forced down into the coal dust, which may be in a mould, and the reaction forces up the plunger 5 and cylinder 1 and causes a rise of oil pressure in the chamber 31. At a preset limit a relief valve, not shown, opens and oil escapes through an outlet 30, the inner plunger then continuing the movement alone. The object of this two-stage compression is to cause the mass of particles under pressure to undergo angular shear strain. When the ram 25 ascends, oil pressure is applied through an inlet 26 to the chamber 27, so forcing down the piston 8 and ejecting the briquette. On the release of the pressure a spring 11 returns the piston 8 and oil re-enters the chamber 31 through an inlet 29. Specifications 807,433 and 809,677 are referred to.