GB417565A - Improvements in and relating to automatic seam-welding machines - Google Patents

Abstract

417,565. Uniting by fusion. BRITISH THOMSON - HOUSTON CO., Ltd., Crown House, Aldwych, London. April 19, 1934, No. 11821. Convention date, April 20, 1933. [Classes 83 (ii) and 83 (iv).] Making steam generators.-An apparatus for welding seams having straight and curved portions comprises welding means moving along a straight path and means for automatically presenting the straight and curved portions in succession into this path of travel. In welding a heat absorber 11 for a water tube boiler having two pairs of angularly disposed straight sides 55, 56 each connected by an arcuate portion 57, an arc welding carriage 2 is traversed by a motor continuously at uniform speed along a track 3, the welding head 1 being transversely adjustable by a hand-operated screw 9. The work is secured to a holder 12 by a clamp 13 which is pivoted at 14, latched at 15 to a bolt 16, and is provided with clamping screws 17. The holder is mounted on a pivot 20 in a crank arm 19 secured to a shaft 18, so that it can be rotatably adjusted on the pivot 20 and secured in position with a straight edge of the work in the line of travel of the carriage and with the centre of curvature of the arcuate portion in alignment with the shaft. The holder is locked to the arm by a hand operated pin 58 passing through one of the holes 59 in the holder. Prior to securing the work in the holder, it is located thereon by a series of pins 42, which are moved into operative position through holes 43 in a shield 44, by a hand-controlled pneumatic motor 48, a locking pin 54 on the plunger 47 preventing rotation thereof. After clamping is effected the pins 42 and 54 are withdrawn, contacts 52, 53 being at the same time connected in the circuit of a motor 21. The carriage is then set in operation to weld the straight portion 55 whereupon an adjustable contact 36 on the carriage completes the circuit of the motor 21 through contacts 38, reversing switch 29 and a limit switch 40. The motor rotates the shaft 18 through reduction gear 22, worm 23 and segment 24. At the same time by aid of a pinion 25 on the shaft 18 engaging a fixed rack 26, the shaft 18 is translated in guides 28 in the direction of travel of the carriage. Since the carriage is travelling continuously, the arcuate portion is thus welded as if it were a straight seam. An arm 41 on the shaft 18 then opens the switch 40 so as to stop the motor 21 and a member 34 on the carriage operates through a lever 31 and link 33 the reversing switch 29. The shaft 18 is now stationary and the portion 56 is now welded. The work holder is then turned on its pivot 20 and locked by the pin 58 so as to bring one of the second pair of straight sides into position. The carriage 2 is then traversed in the reverse direction and when the contact 35 engages contact 37, the motor 21 is operated in the reverse direction so that the second arcuate portion is welded, whereupon the arm 41 opens the limit switch 39 and the member 34 engages lever 30 to reverse the switch 29. The traverse of the carriage may be interrupted between welds.