Abstract: A process for the continuous production of longitudinally welded metal tubes where a metal strip (1) is drawn from a strip supply and gradually shaped into a slit tube in a shaping station (2). The slit tube is welded in a welding system (4) along the edges of the strip, and the welded tube (6) is extracted by an extraction device (5). The welding system (4) is a protective gas arc welding system with several electrodes supplied by separate sources (4c, 4d) of welding current. The electrodes are arranged in succession, in the direction of production. The welding system (4) has two welding devices (4a, 4b), whose electrode tips are directed at a common welding point. Only one of the welding devices (4a, 4b) is in operation at any given time, while the other welding device is in a standby position. When an electrode change becomes necessary, the arc of the welding device in the standby position is first struck by means of an auxiliary arc.

Abstract: A process for the continuous production of longitudinally welded metal tubes where a metal strip (1) is drawn from a strip supply and gradually shaped into a slit tube in a shaping station (2). The slit tube is welded in a welding system (4) along the edges of the strip, and the welded tube (6) is extracted by an extraction device (5). The welding system (4) is a protective gas arc welding system with several electrodes supplied by separate sources (4c, 4d) of welding current. The electrodes are arranged in succession, in the direction of production. The welding system (4) has two welding devices (4a, 4b), whose electrode tips are directed at a common welding point. Only one of the welding devices (4a, 4b) is in operation at any given time, while the other welding device is in a standby position. When an electrode change becomes necessary, the arc of the welding device in the standby position is first struck by means of an auxiliary arc.

Abstract: An electromagnetic oscillating system is disclosed and includes an electromagnet with at least two poles. Each of the poles carry at least one electric excitation winding for connection to an alternating electric field. A rotor is disposed between the poles and includes a shaft that is rotatably disposed within the bore of the electromagnetic windings. The shaft is hollow and has a torsional spring disposed therein. One end of the torsional spring is rigidly attached within the shaft, while the other end extends from the shaft and is rigidly fixed to a stationary point.

Abstract: To regulate welding current and power as a function of welding speed in welding devices for continuous longitudinal-seam welding of metal bands formed into a tube, a speed-dependent voltage value is added to an adjustable fixed voltage value.

Abstract: There is disclosed a method for the continuous marking of electric strands with which annular markings, which are limited in axial direction, are applied to the surface of the strands by means of color jets. The color jets emerge under pressure from at least one nozzle which is driven by an electrical oscillation system, the frequency of which is controlled proportionally to a rate of withdrawal of the strands. For an easy changing of the axial distance between the markings, square pulses are fed to the oscillation system from a converter which converts electrical d.c. voltage into a square waveform signal at a specific frequency. The square waveform drives the oscillation system at the specific frequency. As a desired value, the converter is fed a d.c. voltage which is proportional to the rate of withdrawal of the strand.