Abstract: A metal strip connecting method for welding the tail end of a preceding metal strip and the forward end of a succeeding metal strip. The tail and forward end portions of the two strips which are clamped by respective clampers are cut to required sizes by cutting means which are respectively mounted on frames secured to tables provided with the clampers and which are movable along a passage extending in the lateral direction of the strips. The cut end faces are butted against each other and welded selectively by flash welding or laser beam welding in accordance with the material of the strips. The flash welding is effected by supplying a flash current between the clampers, and the laser beam welding is effected by means of a laser beam machining head which is mounted on the frame secured to either one of the tables and which is movable along said passage.

Abstract: A seam welding machine capable of producing a uniform welding bead quality along the seam of cylindrical articles to be welded such as cans and the like. Commercial AC power is full-wave rectified and then passed through an inverter to produce a relatively high-frequency AC output current. The AC output current is applied through a center-tapped secondary transformer to a rectifier circuit, and thence through a smoothing circuit composed of a reactor and a capacitor to a pair of rotary electrodes. A detector senses when end portions of article to be welded are near the electrodes, and controls the AC power source so as to reduce the welding current at the times when the end portions of the articles to be welded are passing the rotary electrodes.

Abstract: A welding power supply for applying welding current to materials to be welded, particularly, for seam welding operations for thin materials, wherein the power loss of the unit is minimized, a wide range of welding conditions can be accommodated, and the welding quality is improved. The primary winding 7b of a reactor having an iron core is connected between an AC power source 6 and the welding electrodes 3, 4, while the center-tapped secondary winding 7a is connected to a current controlling unit 8. In the current controlling unit, when the welding current starts to exceed a predetermined value, the secondary winding is controlled so that the welding current cannot increase beyond the predetermined value.

Abstract: In a flash welder, instead of using a flexible conductor, the electrical connection to the moveable electrode table is made by a connecting conductor which is slidably connected both to the moveable electrode table and the secondary of the welding transformer. The connecting conductor is mounted on the moveable electrode table in such a manner that, during non-welding periods, it may be retracted within the moveable table, disconnecting it from the transformer and thereby clearing the space between the electrode tables for other workpiece machining operations.