Patent GB-1456722-A (GB)
Title: Extrusion presses
IPC: B28B3/24
Filed: 1974-01-24
Abstract: 1456722 Extruding hollow concrete M J ROUVIN P F ROUVIN AND P E ROUVIN 24 Jan 1974 [24 Jan 1973] 03390/74 Heading B5A A concrete article, having one or a plurality of bores, is intermittently extruded from the outlet of a die 12, Fig. 4, by a reciprocating ram 8, which advances to effect extrusion together with a plurality of tubular cores 1, 3, 5, 7, defining the bores and through which vacuum is applied to remove water from the concrete. The cores 1-7 are retractable through, and independently of the ram 8, being retracted whilst the ram maintains pressure on the concrete. In the Fig. 4 embodiment, the cores 1-7 are retracted prior to the ram 8 completing its advancement. The article, Figs. 1 and 2 (not shown) may comprise rectangular bores arranged either in a row of seven bores or an inner row of six bores in staggered relationship of outer rows of seven bores. Some of the bores are formed by solid cores 2, 4 and 6, integral with the ram 8. The cores 3, 5, and 7, have perforations 1<SP>1</SP> to 7<SP>1</SP> through which the wate ris removed by the vacuum, applied via an upstream chamber 13 with which the cores 3-7 are integral. When the ram 8 is retracted, the mould is charged by gravity from a hopper, via a mould wall opening which is closed during advance of the ram 8. In the Fig. 4 embodiment, the ram 8 and cores 3-7 are connected for their reciprocation respectively to double acting hydraulic concentric pistons 24, 17, the ram 8 and cores 3-7 being simultaneously advanced by displacement of the pistons 24 and 17, upon admission of pressure fluid to chambers 9, 10, and the cores 3-7 then being retracted with the ram 8 continuing to advance, by maintaining pressure fluid in chamber 10 as chamber 9 is vented whereafter, after the cores 3-7 have been fully retracted, the ram 8 is retracted by fluid admitted to chamber 11, as chamber 10 is vented. For removing slurry obstructing the perforations 1<SP>1</SP>-7<SP>1</SP> into the chamber 13, the cores 1-7 are provided with pistons 15 which are movable with, and displaceable by jacks 16 relative to the cores 1-7. In the Fig. 5 embodiment, the ram 107 and cores 102 are independently reciprocated in a similar manner by cams 110, 110a and 112, 112a. Solid cores (104), Fig. 6 (not shown), are also provided intermediate the cores 102, but which extend through the ram 107 for reciprocation by similar, but independent cams. The cores (104) remain advanced with, and are retracted with the ram 107. The cores 102 may be retracted together, or in sequence, and the vacuum is applied from a chamber 206 via flexible piping 203. The cores 102 are each provided with a slurry removing piston 108, which is displaceable with respect to its core by a rack and pinion drive 113, 114, actuated when required from a motor 126 carried by one of the cores 102. In the Fig. 7 embodiment, the ram 207 is provided with integral solid cores intermediate the tubular cores 202, and is connected for its reciprocation to a wheeled trolley 223 running on rails 228. A cam 210 advances the trolley 223, via lever 216 and link 215, the cores 202 being simultaneously advanced via a connection 229 to jacks 227 carried by the trolley 223 and which are inoperative during advance of the ram 207. The cores 202 are retracted by the jacks 227 with the ram 207 in its advanced position maintaining pressure on the concrete, whereafter the trolley 223 is displaced to retract the ram 207, by means of jacks 217. Scraping pistons 208 are actuated by rack and pinion 213, 214.