Patent GB-564260-A (GB)
Title: Improvements in or relating to apparatus for checking or weighing articles, for example, molded articles which have been discharged from an electrically actuated moldingpress
IPC: B07C5/28
Filed: 1942-11-03
Abstract: 564,260. Weighing-apparatus. STOKES MACHINE CO., F. J. Nov. 3, 1942, No. 15486. Convention date, Oct. 21, 1941. [Class 143] [Also in Groups V and XXXVII] Moulded articles of cured resin are ejected from an automatic, electrically-operated moulding press and fall on to a horizontal plate. If the articles are of the right weight, the plate tilts slightly, and a mercury switch moving with the plate is opened. This opening of the switch so prepares the electric circuit of the press that (a) the latter will continue to operate for another moulding cycle, and (b) the plate pivots, at a sharp angle and the articles slide off. If the articles are not of the right weight, the plate does not tilt, the mercury switch remains closed, .the electric circuit is not prepared, and (a) the press stops, (b) the plate does not pivot and (c) an audible or visible signal is operated. In a modification (not illustrated), closing of the switch prepares the circuit. Stoppage of the press may occur before fresh material is fed into the moulds. The plate 5 is disposed at the lower end of a discharge shoot 2, and is pivotally mounted on a rod 8b fixed in the end of a lever 8 carrying another rod 8a pivotally mounted in blocks 6c, 6d secured'on a U-shaped plate 6 pivoted on fixed screws 6a, 6b. The initial (circuit-preparing) tilt of the lever 8 and plate 5 occurs about the knife-edged rod 8a, against an adjustable counterweight 8c, a mercury switch M being secured to and tilting with the lever. This initial tilt is limited by a finger 6e secured to the plate 6. The plate 5 is maintained horizontal during tilting by members 9, 10, 11. A weight 8e renders the lever 8 topheavy and prevents rebound of the plate 5. The assembly is carried by the plate 6 and tends, by its weight, to move clockwise about the screws 6a, 6b, but is normally supported by a cam 7a. Fig. 6 shows a press control system in which a supply S feeds main distributer lines Sa, Sb. A controller motor Mc drives a cam-shaft CS which controls switches A-H (as, e.g., in Specification 515,828, [Group XXXVII]) ; during the operation of the press the motor Mc rotates continuously, except during the resin curing period, when it is stopped by a timing relay 15. A relay 13 controls magnets OM, CM which operate a reversing switch RS controlling a motor Mo. Operation: With main switch 12 up and relay 17 up, the press is closed and ready to be opened. (1) Switch A closes momentarily, thus energizing magnet OM (circuit Sa, A, OM, US, B, 13b, Sb) which operates switch RS to start motor MO to raise the platen Pb. Magnet OM is held-in through contact OMa and switch C. (2) During ascent of the platen, and after or concurrently with the ejection of the moulded articles from the mould cavities, switch E closes momentarily, thus energizing magnet valve MV (circuit Sa, MV, E, F, Sb) to admit air to nozzles Na, Nb. Air from Nb blows the ejected articles into the shoot 2 and escapes through the mesh walls of the shoot, and air from Na strikes the underside of plate 5 to counteract pressure on the upper side of the plate from Nb. An accumulator tank AT balances a manifold MF immediately after the valve MV closes. The residual blast from Na may continue after the residual blast from Nb has ceased, to prevent blast-operation of plate 5. Closing of switch E energizes also a relay 18 to form a hold-in circuit (Sa, MV, 18a, F, Sb) for valve MV. (3) After a while, switch F opens momentarily to de-energize relay 18 and hence valve MV, which closes. (4) Presently, a limit switch US on the press is opened by a part secured to and ascending with the platen Pb. The magnet OM is thus deenergized, motor MO stops and platen Pb remains at its acme. (5) When the moulded articles have dropped through shoot 2 on to plate 5, switch D closes momentarily, whereupon one of two sequences occurs : (a) If the articles are of the proper weight or number, plate 5 is depressed, mercury switch M is opened and relay 17 is de-energized (as shown). A motor 7b having the circuit Sa, 7b, 17a, D, Sb turns the cam 7 through one complete revolution, the cam first allowing the assembly 6-8-5 to drop about the screws 6a, 6b and then raising it to its original position. A switch 7d, closed by the cam, maintains the circuit of the motor 7b during the revolution, after which it opens and the motor stops (b) If the articles are not of the proper weight or number, plate 5 is not depressed, relay 17 remains energized, and a circuit (Sa, A, 13, 17a, D, Sb) is made to energize relay 13 to interrupt the current to switch magnets OM, CM and to control motor. Mc. Motors Me and Mo accordingly stop. Relay 13 also operates a signal 19 through contact 13c and transformer 19a. (6) If plate 5 has tilted, so that motor Mc is still running, switch C is closed momentarily whereby (circuit Sa, C, CM DS, B, 13b, Sb) magnet CM reverses switch RS and starts motor MO to lower platen Pb. (7) Descent of platen Pb is stopped after platens Pb, Pa have closed, either by the opening of switch B or by opening of switch DS after sufficient pressure has been developed between the platens. Switch DS may be opened by a movable press element-e.g. a spring-mounted lower platen, as in Specification 515,790. The mould may be breathed, by rise, dwell and fall of platen Pb, by successive operation of switches A, B, C. (9) Curing: Switch G is closed momentarily to energize clutch coil 15b on time relay 15. This opens contact 15a (thus stopping motor MC) and closes contact 15b to operate motor element 15c which then proceeds to count off the curing time, at the end of which contacts 15a; 15b are re-made and motor MC re-starts. (10) Switch H closes. If plate 5 has returned to its normal position, nothing happens (relay 17 being energized and contact 17b being open), but if the plate has not returned to its normal position a circuit Sa, A, 13, 17b, H, Sb is completed to energize relay 13, stop the press and operate signal 19. Switch H may be omitted. Over-running of platen Pb in either direction is prevented by limit switches LSa, LSb mounted on a moving part of the press. Plate 6 may be tilted mechanically by' a moving part of the press and spring-returned to normal position, in which cases motor 7b, relay 17 and switch H are omitted, or may be tilted by an electromagnet, an air cylinder or a hydraulic cylinder. Specification 515,829, [Group V], also is referred to.