GB1506621A - Electric arc welding - Google Patents

Abstract

1506621 Electric arc welding KONGSBERG VAPENFABRIKK A/S 19 March 1975 [21 March 1974] 11474/75 Heading B3R [Also in Division G3] In a method of are welding, e.g. submerged arc MIG and MAG welding, a dimension of the area to be welded, such as the root gap d, Fig. 3, or a dimension equal to the distance of said area from a reference frame, e.g. dimension x and y in surface welding Fig. 1c is continually measured in front of the arc as it proceeds along the area to be welded. A consumable control wire 6, Fig. 2, is position in the column of the are 4 to influence the size and shape of the arc, and (a) the position, e.g. height u or angle of the tip of the wire with respect to the workpiece is controlled, or (b) the feed rate of the control wire into the, arc is adjusted, in accordance with the measurements made in order to produce in said area a weld with a predetermined cross-sectional dimension, e.g. penetration depth h 1 . Fig. 1a or with b, Fig. lc. In the case where the rate of feed of the wire is adjusted, the average value of the root gap d along the weld may first be determined and the control wire is positioned according to this value and then, during welding, the measured deviation of the root gap from this value is used to control the feed of the wire. The method may be combined with conventional regulation of the welding current, rate of electrode travel, the electrical potential on or current through the control wire &c. An apparatus for performing the method may comprise a measurement unit 13, e.g. a TV camera as described in Specification 1,449,044 for measuring the root gap, a processor unit 12, a computer 11, an interface unit 10 and a control unit 7 for controlling the control wire 6 and possibly also its electrical potential or the current passing through it. The control signals may also be fed to the automatic welding set 8 through interface unit 9 for further control of welding parameters in conventional manner.