Patent GB-763519-A (GB)
Title: Improvements in or relating to a press and method of operating the same
IPC: B30B1/14
Filed: 1954-07-22
Abstract: 763,519. Brick-moulding machines. CHISHOLM, BOYD & WHITE CO. July 22, 1954 [Aug. 7, 1953], No. 21408/54. Class 87(2). [Also in Groups XXIV and XXXIV] A toggle press for moulding bricks has means whereby the driving mechanism is disconnected before completion of the compression stroke, to allow air in the material to escape, and then reconnected for final compression. As shown, the press comprises moulds 14 in which move lower plungers 15, carrying die plates 16 and adjustable by a hydraulic device 20 to vary the depth of the moulds 14, and upper plungers 17 carrying die plates 18 which are operated by a toggle mechanism comprising toggle arms 23, 24, fixed shaft 12 and shaft 25 connecting the toggle arms to which is attached a crank 37 cam-operated through pin 38 from the main drive gear 36. An open-bottomed hopper 27 slides on table 26 into a position over the moulds 14 to fill them with moulding materials. Cam 37c and cam follower 37b co-operate so as to raise sub-frame 8 in the main frame 7, thereby to lift the lower plungers 15 up to the level of the table 26 so that outward movement of the hopper 27 pushes pressed bricks out for removal. The press is started and stopped by a pneumatically operated clutch and pneumatically operated brake. The clutch 40 and its associated plates 40a are driven by drum 39 and upon air pressure being directed from the 4-way, solenoid-operated air valve 43 via pipe 45, passage 47 and pipes 48, 49 to the clutch, plates 40a are pressed into engagement with driven plate member 40b which is in mesh with member 40c attached to the driven shaft 41. The brake 42 is stationary except for the driven shaft 41 rotating a member 42a in mesh with a driven plate member 42b. The application of air pressure from valve 43 via pipes 50, 51 and 52 to the brake causes the stationary brake plates 42c to engage and stop the plate member 42b, thus stopping the rotation of the driven shaft 41. The press may be operated in any of three modes (1) DWELL-in which the toggle arms are drawn towards dead centre to compress the material in the mould, are halted there for a time to allow entrapped air to escape and are then moved through dead centre, (2) INCHING -in which the toggle arms may be moved through a short distance, (3) AUTOMATIC- as in DWELL except that manual initiation of each cycle is not necessary. These modes are obtained by the electrical circuit of Fig. 4 connected to the supply source at terminals 54, 55 and in which for DWELL, switch 56 is set in the "off" position contacting terminals 57, switch 58 in the " run " position contacting terminals 59, switch 60 in the " DWELL" position contacting terminals 61 and switch 62 in the " start " position contacting terminals 63. To start the cycle, switch 64 is put in contact with terminals 65, thus energizing the solenoid 53 and operating valve 43 to pass air pressure to the clutch to engage it and start the press. A series of 4 mechanical switches 66-68 are operated by cams 66a-68a driven from the main gear shaft of the press, and switch 66 keeps the circuit a, 6, c, g, h, i, j, k, e, f, closed when manual switch 64 is released. Switch 66 then opens, solenoid 53 is de-energized and operates valve 43 to release the clutch and operate the brake and so halt the press. Just before switch 66 opens, switch 67 is closed and energizes the time delay motor relay 71 which, after the required DWELL, closes so as to re-energize the solenoid 53 to disengage the brake, re-engage the clutch and allow the press to complete the compression stroke and then reopen to the starting position. Switch 68 is then closed to release the delay relay and to hold the solenoid energized until the return of the press to its starting position when switch 68 opens, solenoid 53 is de-energized, and the press remains inoperative until again started by selector switch 64. For INCHING, switch 56 is set in the " off " position contacting terminals 59, switch 58 is set in the " inch " position contacting terminals 75, switch 60 is set in the " inch " position contacting terminals 73 and switch 62 is set in the " start " position contacting terminals 63. The press may then be stopped and started by on-off switching by switch 76. For AUTOMATIC, the switches are set up as for DWELL except that switch 56 is set to contact terminals 78. Switch 69 is then closed, before switch 68 opens to end an operating cycle, and, before switch 69 opens, switch 66 is closed to initiate the next cycle. The press may be stopped in emergency when under manual control by means of switch 62 or when under automatic working by means of switch 83.