GB367051A - Improvements in and relating to the manufacture of articles of concrete and the like - Google Patents

Abstract

367,051. Moulding pipes, hollowware, &c. by fluid pressure. RUML, B., 32, Pstrossova, Prague, and RUML, F., Platenice, both in Czeoho-Slovakia. Nov. 20, 1930, No. 34945. Addition to 352,968. [Class 87 (ii).] The apparatus described in the parent Specification is modified by the use of a hand regulatable valve between the compressed-air chamber and the balancing valves. In the illustrated form the compressed-air container 4 communicates with the concrete container 5 through a system of valved pipes as shown in Figs. 2 or 3. The container communicates with the multi-part mould 1 provided with a core 3. In the arrangement shown in Fig. 2, a series of hand-controlled throttle valves 15 and 22 .. 25 are arranged in advance of the pressure-equalizing or balancing valves 16 .. 21, which are set to predetermined pressures. By opening any selected throttle valve, the air can be passed through any desired number of the equalizing valves, while by regulating the throttle, the pressure in the container 5 can be varied even when the air is passing along any particular circuit. On opening valve 27 the whole of the equalizing valves are cut out. Fig. 3 shows a modified arrangement in which each branch pipe has its own throttle and equalizing valve each of the latter being set to different pressures. By manipulating the throttle valves, the working pressure can be varied to suit different materials and operations at will, but as a rule a large initial pressure will be required to set the concrete in motion, a smaller, but increasing pressure to fill the mould, and a much higher final pressure to consolidate the article and drive out moisture. Rapid setting of the outer layers of the moulded body is promoted by passing steam or hot air through channels 28 in the mould. The core may be withdrawn while the inner layer is still plastic or when it has just set and may be rotated continuously or at intervals, so that the measured resistance offered to rotation determines the time for withdrawal. If the core has been heated it may be suddenly cooled before withdrawal.