GB1258051A - - Google Patents

Abstract

1,258,051. Compacting particulate materials. ENGLISH CLAYS LOVERING POCHIN & CO. Ltd. 6 Feb., 1969 [6 Feb., 1968], No. 5967/68. Heading B5A. Particulate materials containing large quantities of entrained gas, e.g. china clay, metallic oxides, silica, silicates, carbonates, tales, organic and inorganic pigments, dyestuffs, carbon black, pharmaceuticals, pesticides, fertilizers and foodstuffs, are compacted in a mould cavity in the presence of a plurality of elongate tapering members which are introduced to extend within but not completely through the cavity, and which members are withdrawn therefrom at the same time as or before release of the compacting pressure, whereby entrapped gas escapes from the material to avoid cracking thereof both as the compression is being applied and after the members are withdrawn. The compaction may occur in up to 8 separate such stages of increasing pressure, e.g. 50 to 500 1b. sq. inch, in the same or different compaction presses through which a plurality of moulds is sequentially transported on a rotary table. In the Fig. 1 embodiment wherein one mould is incrementally conveyed on a rotary table between a press and a mould filling and ejection station, the mould comprises a platen 1, resting on compaction press rails 31 at the pressing station, and enclosed by side walls defined by two right-angled members (36, 37), Figs. 4-6 (not shown), the latter whereof is hinged for slight opening movement to facilitate release at the ejection station. The, or each, compaction press includes a base 14 supporting the rails 31 and rigidly attached by three struts, e.g. 4 and 5, to a triangular top member 17 connected to one end of pivoted arms (7, 8), Fig. 2 (not shown), which are connected at their other ends to a column 9 which is connected, by a plate 10 and struts 18, to a compression applying plunger 13. This arrangement provides for simultaneous and equal upward or downward movement of base 14 as the plunger 13 is downwardly or upwardly displaced by pistons 11 and 12. The tapering members 21 are supported. by a frame 22 vertically displaceable with respect to plunger 13 by cylinders 23 and 24 on plate 10, the members 21 passing through holes in the plunger 13 which holes, together with the members 21, are provided with labyrinth seals permitting the egress of entrapped air but not of the material. Pressure is simultaneously applied to the material with simultaneous penetration by the members 21, on movement together of the plunger 13 and platen 1. The members 21 are withdrawn and the cycle may be repeated. The platen 1 is locked in its raised position by cams (38, 39) provided in the mould walls, and the base 14, plunger 13 and members 21 are separated from the mould to permit this to move on the turntable to the filling/ ejection station, where the cams (38, 39) are released and the mould walls opened slightly to permit release of the moulded block. In the Fig. 8 embodiment, a plurality of moulds 134a to 134d are incrementally indexed in one direction on a toothed ring 140 through a mould filling station A, compression stations B and C, and an ejection station D, the ring 140 being driven through a one -way clutch 157 from a sector gear 153 reciprocated by a crank drive 152 from a gear-box 151 and a motor 150. At station A a pre-weighted amount of material is fed to accumulate in the S-shaped duct 161 of a vibrated hopper 160, the hopper and duct 161 then being rotated about axle 162 to discharge material into the mould. A roller 169 levels the material in the mould on passage thereof to the pressing stations A and B, each similar to the Fig. 1 embodiment. At station D, the mould is slightly opened and platen 1 raised, by an hydraulically actuated ejector 170, to a position where the moulded block is displaced by a ram 173 on to an endless conveyer 174 for transport to a wrapping station. The hydraulic cylinders controlling the press and ejector movements are controlled by valves 180 actuated by cams 181 on a shaft 182 rotated, through clutch 184, from gear-box 151. The hopper 160 is rotated about shaft 162 by a cam 185 actuated linkage 186. Sensing devices (not shown) are provided to disengage clutches 157 and 184 prior to each stage in the event of malfunction of any stage, e.g. the absence of feed to shoot 161 or the non- retraction of an hydraulic ram. In a further embodiment, Figs. 9 to 13 (not shown), the moulds are transported through a mould filling, two compression, and an ejection station on a rotary table indexed by a Geneva mechanism. The mould side walls are vertically slidable on the mould table and, during rotation, the platens slide on arcuate rails and the mould walls are supported by rollers on an arcuate rail. At the compaction stations the mould walls run on rails which are hydraulically retractable, and the platens are supported by a stationary press frame, whereby the mould boxes are free to move vertically and the platen remains stationary. In this embodiment, the mould walls are opened and closed on entering and leaving the ejection station by cams which rotate an eccentric pin attached to one of the right-angled side wall members.