GB554687A - Improvements in electric welding - Google Patents

Abstract

554,687. Supply systems for welding arcs. LINDE AIR PRODUCTS CO. Nov. 13, 1941, No. 14604. Convention date, Oct. 3, 1940. [Class 38 (iv)] ] [Also in Group XXII] Two independent and separate welded seams in the same work piece are simultaneously effected by depositing a quantity of fusible mineral material over each of the seams, inserting one end of each of a pair of fusible metal electrodes into each quantity of the fusible material and connecting the opposite ends of the electrodes to the opposite terminals of a single source of current so that the current passes in series through the electrodes, fusible material and work. The fusible material may consist of unbonded granular material as described in Specifications 443,723, [Group XXII], and 438,855, [Group II]. A web S is simultaneously fillet welded at opposite sides to a plate P. by a pair of welding electrodes 10, 16 connected through a switch 22 to the opposite terminals of a source of direct or alternating currents. The feeding of the two electrodes may be automatically controlled independently by separate voltage responsive means. Such an arrangement is shown in Fig. 2 as applied to the welding of two heads H to a storage tank or pressure vessel. The electrodes 34, 36 are connected through adjustable reactances' 44, 46 to the ends of the secondary 42 of a transformer. A resistance 70 is connected in parallel with each electrode. The coil of a relay 68 is connected to the rod 34, and to an adjustable contact 72 of the resistance so as to impress a definite portion of the voltage drop between electrode 34 and work on the relay. Wherever the welding voltage exceeds a preselected value the relay is energized and the arms 74, 76 closed so that an auto transformer 66 with adjustable contact 82 is connected to operate the motor 62 to rotate the feed rolls 60 to advance the electrode 34. The electrode 36 is similarly controlled. Ground connections 96, 96<SP>1</SP> may be provided so that if one welding head completes its seam before the other it may be shunted out. The Specification as open to inspection under Sect. 91 states that the process applies to ordinary metallic arc welding. This subject-matter does not appear in the Specification as accepted.