Patent GB-785017-A (GB)
Title: Pressing of bricks, briquettes and the like
Inventor: BARDSLEY NORMAN
IPC: B28B3/02
Filed: 1952-10-23
Abstract: 785,017. Machine for making bricks &c. SUTCLIFFE, SPEAKMAN & CO., Ltd. Jan. 25, 1954 [Oct. 23, 1952], No. 26683/52. Class 87(2). A press for the manufacture of bricks, briquettes or the like comprises means for applying at least two pressings through the same plunger to material in a mould and means comprising a movable taper plate to alter the effective stroke of the plunger whereby the pressure on the material in the second pressing is greater than that in the first pressing. The pressure is applied upwards and is resisted by a pressure block resting on the mould table. Between a pressing foot 1, mounted on the crosshead 2 of the press, Fig. 1, and the ends of the pressing plunger (not shown), taper plates 3, 4 are interposed, 4 being arranged to slide over 3 so that, when the taper plates are in the position of minimum overlap, the material in a mould will be given its first pressure and, in the position of maximum overlap, the plunger will have a longer effective stroke and the material will be given its second, higher, pressure. The surface of the taper plate 4 may be covered with a plate 14 of heavy-duty alloy. The material is in one of a series of moulds mounted on a horizontal table which is rotated intermittently so that succeeding moulds are brought into the pressing position during the return movement of the plungers from a second pressure stroke. The movements of the taper plate and of the table are controlled by a cam drum 30, Fig. 6. A cam segment 35, Fig. 7, rocks an arm 39 and thereby opens a compressed air valve 41a which admits air, through an air line 28, to a cylinder 23, Fig. 5. A pawl 21, connected to the piston of the cylinder, is thereby disengaged from a catch wheel 20 and the mould table is released. The cam drum 30 is chain driven from the crankshaft of the press and geared to rotate at half its speed, and therefore two pressings are given to the material for each rotation of the cam drum. Another cam segment 35, see Fig. 6, has just previously rocked another arm 39 to open a valve 41c and admit air, through an air line 16, to a cylinder 9 which has, through a bell crank 6, withdrawn the plate 4 outwards so that, when the press plunger descends, the lower pressure is applied to the material in the mould. As the cam drum continues to rotate it rocks a third arm 39 which opens a valve 41b to admit air to the other side of the piston in the cylinder 9, with the result that the taper plate 4 is moved inwards and when the plunger makes its second stroke the higher pressure is applied. The pressures may be varied by altering the amount of overlap of the taper plates, by varying the piston stroke in the cylinder 9, or by adjusting the limit stop 17 of the bell crank lever 6. Provision is made for the escape of residual air from the cylinders by making the valve stems hollow ; thus, in the case of the cylinder 9, when the valve 41c is closed, as in Fig. 7, any air present under the piston in the cylinder escapes round the end of the valve rod 43, through its bore, out of a hole 50 in the valve rod and eventually out of a vent hole 51 in the casing. Cam drum. The drum 30 carries three circumferential projections 33 and arcuate segments 36, L-shaped in cross section, have each one arm resting against the side of a projection and the other seated in a groove between two projections where it is secured to the drum by screws passing through slots 37 which allow for adjustment. The side arms of the segments 36 are flanged and the flanges 35 bear on the circumference of the adjacent projection 33, each cam surface being formed by the flanges 35 of two segments 36 in adjacent grooves 34 with the flanges bearing on the same circumferential projection 33. The mechanism may be arranged to give more than two pressure strokes for a mould position. Electrical operation, instead of compressed air, may be used, the air valves being replaced by switches and the aircylinders by solenoids, or a valve rod may be replaced by a solenoid plunger. The press can be used for clinker, iron ore, concrete, refractory material and sand lime.