Patent GB-1446931-A (GB)
Title: Depostiion of weld metal
IPC: B23K9/02
Filed: 1973-10-30
Abstract: 1446931 Welding by fusion TELEDYNE Inc 30 Oct 1973 [17 Nov 1972] 50453/73 Heading B3R [Also in Division H2] In build-up deposition of fused metal upon the volute interior surface of a dredge pump housing (Fig. 3, not shown), wherein the housing is disposed on its side with its axis vertical and a radially extensible, generally horizontal, boom 13 carrying a consumable electrode arc welding apparatus is rotated approximately about said vertical axis, the boom radial extension and retraction is controlled by a cam plate 31 having a suitably shaped cam slot 32 engaged by a boommounted follower roller 34 so that the welding apparatus is maintained approximately a constant distance from the housing interior surface, and the boom rotational speed is controlled by an SCR drive 100 (Fig. 12) including a potentiometer 130 rendered dependent, by a rack and pinion 36, 49, on said boom extension and retraction and acting on a boom rotation reversible variable-speed electric motor 71 so that the welding speed is maintained approximately constant. The cam slot 32 is such that weld deposition may be effected into the tangentially disposed pump discharge duct. Reversal of boom rotation and re-positioning of the nozzle, 25, of the welding apparatus in readiness for the next weld bead are controlled by limit switches 82, 83 having operating rollers 51 coacting with adjustable cam stops 39, 40 carried by the boom, weld puddle runout at boom rotation reversal being decreased either by ceasing both weld deposition (e.g. by cessation of electrode wire feed) and boom rotation for a timed period along with nozzle repositioning, or, as particularly described, by ceasing wire feed along with nozzle repositioning while continuing boom rotation in its existing direction and time-delaying boom reversal until the nozzle has passed the point of deposition discontinuance, deposition being resumed when the nozzle passes said point on boom return. The boom 13 is radially movably mounted in a housing 14 fast with a vertical shaft 15 which is journalled in a support plate 10 and rotatable by the motor 71 via a chain and sprocket drive 16- 18. The plate 10 is supported by extensible arms 11 on legs 12 screw-jack-adjustable in height and has the cam plate 31 clamped thereto at 38. The boom carries at one end a vertical post 21 in turn carrying a horizontal member 20 on the end of which is mounted the nozzle 25. Nozzle position with respect to the boom may be variably adjusted and indexed by angular nozzle movement by a reversible electric motor 74 acting through worm gearing, and by vertical and horizontal movement of the member 20 by reversible electric motors 73, 72 acting respectively through a screw 19 and nut and a pinion and rack 23. A vertical post 29 attached to the housing 14 supports a unit 30 driven by a motor 75 and feeding electrode wire to the nozzle 25 through a guide 37. Deposition welding may be gas-shielded or, preferably, self-shielded using tubular consumable electrode wire, and said welding proceeds from the relatively flat portion of the interior surface of the housing to the centre line or greatest diameter portion thereof. As described, control is by a circuit (Fig. 12) including main and remote control panels 27 (Fig. 10), 28 (Fig. 11) incorporating toggle switches 85-92, 94, a wire inching button 93, and VATs (variable autotransformers) 95-97, 99. The VATs 96, 97, for nozzle index distance, vary the speed of the motors 72-74 so that for constant running times index distance is varied. The circuit also includes rectifiers, rectifying 110V A.C. for D.C. motor operation, and timers effective at the above boom reversals.