GB1232391A - - Google Patents

Abstract

1,232,391. Slab press control circuit. DAVY & UNITED ENG. CO. Ltd. 18 Sept., 1968 [22 June, 1967], No. 28973/67. Heading B5A. Apparatus for controlling a slab moulding press wherein the slab is compressed between platens by one or more rams acting on at least one of the platens, comprises means settable to the dimension of the slab, a computing circuit for computing the required fluid pressure for the rams from a preset moulding pressure and the slab dimensions which computing circuit produces a signal proportional to this fluid pressure and means responsible to the signal to control the ram fluid pressure at the desired value. An initial circuit may be provided to calculate the number of rams needed according to the dimensions of the slab. As shown, the slab size is set on dials 12, 13 of control desk 14. The control desk calculates the number of rams needed (N) and passes this signal together with signals corresponding to the slab length and width to a computing circuit 18 where the ram pressure is calculated (inputs corresponding to ram area and preset moulding pressure (potentiometer 30) being provided). A signal corresponding to this pressure is fed through amplifier 21 to a relief valve 22 which operates the valves 23 on the rams. A pressure transducer 24 in the fluid feeds back the actual pressure in the rams to amplifier 21 and also provides a signal to a second computing circuit 26 which calculates the pressure on the slab, and shows it on dial 28 and provides visual indication via light 32 and 33 as to whether the pressure is at or below a predetermined minimum permissible pressure set by control 31.