GB1357986A - Press for the manufacture of ceramic and refractory articles - Google Patents

Abstract

1357986 Compression moulding U WALCHHUTTER 1 Sept 1972 [2 Sept 1971 31 May 1972] 40704/72 Heading B5A A press for ceramic and refractory bricks and tiles comprises vertical columns 4 mounted between stationary crossheads 1, 5, an intermediate crosshead 6 sliding on the columns and carrying a mould part 7 which co-operates with a complementary mould part 3 on erosshead 1, a means for lowering the crosshead 6 to partly close the mould, and further means which follow the crosshead down and then form an abutment against which an hydraulic ram 21 mounted on the intermediate crosshead 6 reacts to effect a compression stroke. After removing previously moulded articles and refilling the mould cavities by means of a horizontally reciprocating carrier 53 (Fig. 2, not shown) the cross-head 6 is lowered by releasing pressure from rams 12 and pressurizing rams 16. The downward movement is limited by resistance of permanently pressurized low pressure rams 13 and by the moulding material which is precompressed thereby. In the embodiment of Fig. 1, an hydraulic motor 44 which is mounted via rollers 46 on supplementary crosshead 45 is operated to turn a spindle 42 threaded through the stationary crosshead 5 to lower the spindle until it contacts the piston 23 of ram 21. Low pressure. fluid is delivered to chamber 19 of ram 21 to effect a first compression step after which fluid is discharged from chamber 19 and fed to chamber 37 to collapse the ram 21 and permit the compressed material to expand and permit trapped air to escape. The spindle 42 is lowered further to re-engage the collapsed ram, whereupon high pressure fluid is delivered to the ram to effect a final compression stroke. After compression the spindle 42 is retracted and rams 12 pressurized to raise the crosshead 6 until it engages permanently pressurized low pressure rams 17. The rods of rams 13 and 17 are adjustable by screwed terminal members 14 and 18. In the embodiment of Fig. 8, a supplementary crosshead 56 is connected to the piston of ram 21, through a member 55 engaging a seat 54, so that the lowering of crosshead 6 by rams 16 is limited when the heads 59 of rods 58 carried by the supplementary crosshead reach the ends of chambers 60. The supplementary crosshead carries the lower part 63a of the device of Fig. 10, the upper half 64a being carried by a shaft 67 in the upper crosshead 5. The teeth of the device are intermeshed in Fig. 8, but become separated on lowering of the crosshead 6 whereupon the upper part 64a is rotated by a ram 71 connected to shaft 67 to align the teeth and prevent raising of the crosshead 6 when ram 21 is operated to effect compression.