Patent GB-1259072-A (GB)
IPC: B23K9/30
Filed: 1970-03-03
Abstract: 1,259,072. Welding by fusion. CONSTRUCTIONS METALLIQUES DE PROVENCE. 3 March, 1970 [4 March, 1969; 25 July, 1969], No. 10112/70. Heading B3R. In a welding machine for butt welding sheets 1, 2, a welding head 37 is oscillatable transversely of the weld seam by a reversible electric motor 29, and the oscillation amplitude is automatically controlled in accordance with weld preparation width by detecting means which is oscillatable with the head, senses the edges of the weld preparation, and acts on a reversing switch in the circuit of the motor 29. The welding head may be an oxyacetylene or, as shown, a consumable electrode arc torch. As shown, the head 37 is mounted in a support 38 connected, by a screw-adjustable slide 39 for height adjustment, to an arm 35 pivoted at 36 on an extension 31 of a carrier 30 which is mounted on a support 10 pivoted at 11 on a carriage 5. The latter is self-propelled on a rail which is secured to one of the workpiece sheets 1, 2 and is substantially parallel to the seam. The carrier 30 is transversely movable on the support 10 by a further reversible motor 9. A roller 16 carried by the carrier 30 is maintained in contact with the workpiece by resilient buffers 17 at the pivot 11. The motor 29 oscillates the arm, and hence the head 37, via a reduction gear integral with the motor, a crank 33 and a connecting rod 34. A detector capsule 48 is double-pivoted to the extension 31 and is in slidable connection with the head 37 so as to oscillate with the latter. The capsule 38 is a known metal body proximity detector and contains an inductance in a circuit of an oscillator such that when the capsule reaches a weld preparation edge the torch oscillating motor reversing switch is actuated. Thus the head oscillation amplitude is controlled in accordance with weld preparation width despite width irregularities or carriage rail/weld preparation deviation. The ratio between head and detector amplitude may be adjusted by varying the distance between the detector and the head. Means automatically maintaining the axis of oscillation centrally of the seam and thereby maintaining arc length substantially constant comprises a lug 40 of the crank 33 and symmetrically disposed, variably spaced, lug position detectors 41. The detectors 41 may be metal body proximity detectors, or may be lugcontacting contacts with a voltage applied to either the lug or the contacts. Detection of the lug by either detector 41 actuates a switch of the reversible motor 9 to centre the pivot 36 over the weld seam. In Figs. 6-8 (not shown), the weld preparation edge detection is by two electrically conductive needles (52) which are adjustably mounted on a laterally adjustable support (54) pivoted on the end of the head support 38 and spring- loaded towards the workpiece. The height of the support is determined by an adjustable curved stop (60) contacting the workpiece. Reversal is responsive to needle/sheet edge contact. In a further embodiment, reversal is responsive to actuation of switch means carried by the needles (52). In Figs. 1, 2 (not shown), the motor 9 is fast on the carriage 5, and the latter is driven along a rail via at least one rail-engaging knurled edgeroller (6).