GB1217565A - Method of and power supply for electric arc welding - Google Patents

Abstract

1,217,565. Arc welding systems. LINCOLN ELECTRIC CO. 8 July, 1968 [10 July, 1967; 20 June, 1968], No. 32447/68. Heading H2H. The power supply for an arc welding system wherein an arc x is maintained and a droplet on the end of an electrode periodically contacts a weld pool, includes first and second D.C. power sources G and S, supplying the workpiece and electrode, in parallel. The first source has a short-circuit current note of rise less than 60,000 (preferably between 15,000 and 40,000) amperes per second and a voltage output sufficient to maintain an arc between the electrode and workpiece for drop formation. The second source has a short-circuit current rate of rise in excess of 60,000 (preferably between 100,000 and 1,000,000) amperes per second and a voltage output such as to supply substantially no current when an arc exists and a pulse of current when the droplet still on the end of the electrode contacts the weld pool. As shown, the workpiece W and motor-driven electrode E are connected to respective terminals CT, CP to which the first and second sources, G and S, are connected. The second source is an alternator A on the same shaft as the first source generator G, the alternator being connected through a three-phase rectifier bridge 41. The generator G is controlled by a settable voltage regulator R which can be connected to the terminal CT, CP and controls the field windings 33 of the generator G. The regulator R can also be connected across a resistor 44 in the field winding circuit when the second source S is disconnected. Alternatively the first source G may be batteries with an inductance or rectified A.C. supply with an inductance of D.C. from a rotating generator with or without an external inductance. The second source S may also be a battery or current transformer with a rectifier.