GB733667A - Improvements relating to electric arc-welding apparatus - Google Patents

Abstract

733,667. Control systems for welding arcs. LINCOLN ELECTRIC CO. Feb. 25, 1953 [Feb. 29, 1952], No. 5235/53. Class 38 (4). [Also in Groups XXII and XXXVII] In arc welding apparatus comprising a torch supporting the end of a flexible wire electrode and means for feeding the wire from a stationary storage device, the torch is on a self-propelled carriage driven by its own motor at a speed variable independently of the electrode feed rate and adapted to travel along a supporting surface. Electrode wire W, Fig. 1, is fed by means of a motor 3 from a stationary storage reel 1 through a flexible tube T to the torch mounted on the self-propelled carriage C. The carriage C carries a motor 11, Fig. 2, which through gearing drives a belt 18 engaging the workpiece W<SP>1</SP>. A direct currect exciter supplies cables 45, 46, Fig. 5, and the welding current supply terminals 42, 43 are connected by cables 40, 41 to the torch and work respectively. The switch positions are those in which no energy is supplied by the exciter. To commence welding with the electrode tip up within the torch, the exciter is switched on, the switch 53 is placed in the "Tractor" position with pole 53a open and 53b closed. The switch 59 is placed in the "on-weld" position with pole 59a closed and 59b open to increase the excitation of the field 47 of the welding generator through the rheostat 58. The tractor switch 48 is closed to energize the motor 11 which moves the carriage over the work and to energize the relay solenoid 50, the contacts 54a, 54b, 55a, 55b, and 56 thereof moving to the left as seen in Fig. 5. Current is now fed to the electrode feed motor 3 from cables 40, 41 via resistance 63, contact 56 and contact 53b. The motor slowly feeds electrode to the work. When an arc is established a relay 57 on the cable 40 closes its contacts 57a, 57b to produce full excitation of field 47 and thus full welding current and to produce greater speed in the motor 3 by shorting out resistance 63. Welding then -proceeds with automatic regulation of arc length due to the characteristics of the generator. To stop welding the switch 48 is opened to stop motor 11 and de-energize relay solenoid 50. The relay contacts move to the position shown in Fig. 5 and current is fed to the motor 3 in the reverse direction and through a different path. The motor runs in the reverse direction at a greater speed and withdraws the electrode rapidly from the work. This action cleans flux from the electrode end. The arc is broken and relay contacts 57a, 57b open to stop motor 3 and thus retraction of the electrode. Operation of the switches when the torch is used manually is described. To advance the electrode without its being at full potential and without starting the motor 11 the switch 59 is put in the " Offinch position, the switch 53 is put in the "Hand" position and a push-button 66 is pressed to operate the feed motor 3, excitation current for field 47 passing through a resistance 61.