Patent GB-749245-A (GB)
Title: Improvements in or relating to electric controlling apparatus, particularly for machine tools
IPC: B23Q5/28
Filed: 1952-05-19
Abstract: 749,245. Control of several motors; controllers. VICTORIA MACHINE TOOL CO., Ltd., FRYE, J., SEIDEL, A. Aug. 19, 1953 [May 19, 1952], No. 12596/52. Class 38(3) [Also in Group XXII] Relates to electrical control apparatus which may be used for effecting selected cycles of movement of the work tables of machine tools, comprising four switches and four corresponding dogs, and means whereby relative movement between the dogs and switches is adapted to take place according to the movement of the work table. During the travel of the table, each dog can engage its corresponding switch only, operating the switch when the relative movement is in one given direction. As shown, the switches comprise feed-left switch AFL, feed-right switch AFR, quick-travel-left switch ATL, and quick-travel-right switch ATR, and, when these are momentarily actuated, they " establish maintained circuits for the respective motor-controlling contactors FLw, FRw, TLw, and TRw. The circuits of the contactors FLw, FRw are maintained through relays AFLw, AFRw, the circuits of the contactors TLw, TRw being maintained without the use of relays. Momentary actuation of any of the dog-operated switches thus establishes the circuit of its own contactor, but opens that of any other of the contactors. The relays AFLw, AFRw are self-maintaining and so maintain the closure of contactors FLw, FRw. whereas the contactors TLw, TRw establish, upon closing, maintaining connections for themselves. The table may be controlled manually by actuating a change-over switch AU, the system comprising push-buttons regulating the appropriate contactors for quick or slow travel in either direction; and the arrangement being such that operation of the changeover switch for hand control renders the automatic control inoperative, but actuation for automatic control does not effect the hand control system. The contactors TLw, TRw are maintained energized during manual operation only so long as the corresponding push-buttons are depressed; but, if the circuit of either of these contactors has been established, actuation of any non-corresponding pushbutton is without effect. Push-button operation effects maintained or temporary closure of the contactors FLw, FRw, according to the manual or automatic positioning of the change-over switch. Interlocks are provided so that, if the table is making a feed movement under automatic control, actuation of the manual switch for reverse feed movement is effective so long as the manual switch is operated, release of the manual switch allowing the original movement to be continued. Under the same circumstances, actuation of the manual switch for quick travel in the opposite direction is effective, the contactor for the feed movement being de-energized, whilst operation of the manual switch for quick travel in the same direction is without effect. When the table is making a quick travel movement under automatic control, actuation of a manual switch for any other movement is without effect, whereas, operation of the manual switch for the same movement interrupts the automatic control and institutes manual control. The quick and feed movements of the work-table are performed by respective electric motors which are coupled to the table through differential gearing so that, if both motors run together, the net movement of the table will be that of the quick-travel motor. The control system comprises a dog-operated stop switch AS, limit switches L/L, L/R, stop and start pushbuttons SP, ST and a stop signal lamp SL. A contactor SCw, connected in series with selector switch S, controls a motor driving the spindle of the machine. Specification 702,226 is referred to. Reference has been directed by the Comptroller to Specification 702,226.