Patent GB-458269-A (GB)
Title: Improved arc welding system
IPC: B23K9/12
Filed: 1935-06-15
Abstract: 458,269. Uniting by fusion; electric supply apparatus. BABCOCK & WILCOX, Ltd., Babcock House, Farringdon Street, London.-(Assignees of Trainer, J. E.; Ridgewood Road, Akron, Ohio, U.S.A.) June 15, 1935, No. 17325. Convention date, June 16, 1934. [Class 83 (iv)] [See also Group XXXV] In an arc welding system comprising relatively movable electrodes, one at least of which is consumable, the electrodes are connected in an alternating current are circuit and the relative movement of the electrodes is effected from a unidirectional current circuit, means responsive to the electrical condition of the arc influencing the unidirectional current circuit to adjust or vary the rate of relative feed of the electrodes. The welding head P is fixed to a support 16 vertically adjustable in a beam N, which carries a rack 3 and may be traversed by a motor 6 through reduction gear when welding longitudinal seams. A backing-up strip 33 for engaging the seam when welding longitudinal, transverse or circumferential seams is supported by a jack 32 in a member 31 connected at opposite sides by cables 29, 39 to the opposite ends of the beam so that it may be moved with the beam when welding longitudinal seams. In welding circumferential seams, the work O, such as a tank or penstock, is mounted on pairs of rollers 18, 19 rotated by a motor 26 through reduction gear 27. A jet of inert or reducing gas may be supplied to the arc. Current is supplied to a coated electrode Z by shoes 301 engaging bared projections 300. To effect a weld a reversible electrode feed motor 114 is rotated by a 60 volt direct current and is automatically controlled bv variations in the arc. The operation is started by closing contacts 168, 169, whereupon a solenoid is energized to close switch A. Thereupon solenoid of switch C is operated to close switch C and solenoid D is energized to close contacts 162, 164 and thus close the welding circuit containing the secondary of a transformer 159 and reactor 160, when a carbon pencil is placed across the gap between the work and electrode. At the same time a solenoid F is energized so as to raise the plunger 163 and close spring-opened contacts 170, 171. Solenoid of switch B is thus energized and contacts 200, 201 and 202, 203 are thus closed to rotate the motor 114 to feed the electrode towards the work, the field of the motor being previously energized through contacts 172, 173 when switch A is closed. The solenoid of switch F is protected before the arc is struck or in case the voltage is excessive due to a long arc or failure thereof by a resistor 176 arranged in shunt with contacts 208, 209 of a spring closed switch E. This switch is normally open, its solenoid being in a circuit parallel with that of switch F. If the arc lengthens the plunger 163 is raised sufficiently to open contacts 172, 173, whereupon the speed of the motor is increased by current passing through shunt circuit containing a manually adjustable rheostat 177, until the arc shortens, when the plunger 163 is moved down by spring 174 to re-engage contacts 172, 173 without opening contacts 170, 171, so that the motor operates at its former speed. If the weld rod freezes to the work the switch F is shortcircuited and the contacts 170, 171 opened to de-energize solenoid of switch B, whereupon spring 210 closes contacts 201, 204 and 203, 205 to reverse the motor. As the contacts 172, 173 are engaged the motor operates in this direction at slow speed to re-establish the arc. When this is effected the solenoid of switch F reengages contacts 170, 171 and energizes solenoid of switch B to operate the motor in the forward direction. The fast rate of feeding is faster than and the slow rate slower than the rate the rod is consumed in the arc. The critical voltage of the arc may be varied by a manually adjustable rheostat 178. The Specification as open to inspection under Sect. 91 describes a construction of arc welding apparatus for welding with bare, coated or covered electrodes in which angular adjustment of the electrode in several planes is effected. This subject-matter is described in Specifications 33123/36 and 458,580 and does not appear in the Specification as accepted.