GB881897A - Improvements in or relating to apparatus for controlling slipping of continuous electrodes - Google Patents

Abstract

881,897. Control of several motors. SHAWINIGAN CHEMICALS Ltd. June 3, 1958 [June 5, 1957], No. 17633/58. Class 38 (3). [Also in Group XI] A furnace electrode 2 is supported partly by pressure contact shoes suspended by a casing 11 from a yoke 12 suspended from a fixed beam 12 and partly by auxiliary clamps 15 in a ring 17 on a secondary yoke 18 supported by screw jacks 25 on the yoke 12. The pressures on the shoes 3 and clamps 15 are such that each group supports the main but not the whole weight of the electrode, which is lowered into the furnace by reversible motor 62 acting through gears 24 on the jacks 25 between limit switches 26, 27. The furnace has several electrodes, e.g. three for a three-phase furnace, and they are lowered virtually simultaneously by a repeat cycle timer 42, the contacts 42c of which close for 20 seconds once an hour. Stop cycle timers 43-45 are then energized for separately adjustable periods, e.g. about 5 seconds and energize solenoid coils 52L-54L of reversing magnetic switches 52-54, thereby energizing motors 62-64 to lower the electrodes by lowering the yokes 18. The return of the yokes to their higher position may be effected by push-buttons 49-51 once a day, or by allowing the yokes to reach lower limit switches 27, 37, 47. The switch 27 energizes a solenoid coil 52L to close a reversing magnetic switch 52 to reverse the motor to raise the yoke 18. Auxiliary contacts 52RC complete a holding circuit maintaining operation of the motor until the yoke 18 reaches the upper limit switch 26. A " Wisdom ribbon " (see Group XI) attached to the electrode may replace the auxiliary clamps 15. Warning devices may denote operation of a limit switch. Although frequent intermittent lowering of the electrodes is preferred, a continuous lowering may be effected by running the motors slowly. The screw jacks may be replaced by hydraulic pistons.