Abstract: The sheets which are to be butt welded are positioned with their edges in contact with one another. To reduce the gap to a width acceptable for laser welding, at least one sheet is plastically deformed along the line of the joint so that material flows towards the gap, reducing the width of the gap. In this way, sheets cut to size with much less precision can be welded together.

Abstract: As preparation for the seam welding of different thickness sheet metal blanks (10 and 12), at least the thicker (10) of the two blanks is reduced in thickness, preferably by chip machining, in its edge region (11) which is intended for welding. Since the edge regions (11 and 13) which are to be welded then approximate to each other in their thicknesses (t1+t2), practically symmetrical conditions with regard to the joint plane exist for the welding operation, so that the welding can proceed with substantially the same controllable welding parameters as in the seam welding of sheet metal blanks of equal thickness. The process is suitable mainly for use in mash seam welding, but also in other seam welding processes, such as for example, in laser welding.

Abstract: A compound sheet with a welded seam is arranged on a table (2) of the device (1). By lowering a cutting and bending punch (4), a cutout is cut from the compound sheet and bent downwards. A pulling device is arranged inside the device (1) underneath the table (2) to seize the downwardly bent cutout and tear it off the compound sheet. The quality of the weld can be evaluated by visual inspection of the appearance of the rupture point, in a known manner. In this way, tear test specimens of consistent quality and informativeness can be prepared very quickly and easily.

Abstract: A roller head (10) for a resistance seam welding machine has an internally located sliding contact current transmission device (24) between stator 12) and rotor (14) and is composed of a pair of circular ring-shaped discs (26, 26') which extend radially between rotor and stator, are fastened to the rotor on their outer circumferences, carry axial sliding contact rings (32,32') on their inner circumferences, and are flexible designed in their intermediate parts (28,28') between inner and outer circumferences. These sliding contact discs (26,26') are composed of a copper mesh, to which the axial sliding contact rings (32,32') are fastened. Thin-walled metallic diaphragms can also be used instead of the copper mesh. The roller head (10) can transmit high welding currents. As a result of the flexible design of the sliding contact discs (26,26') the contact presssure, which is created by a stack of plate springs (40), remains constant even with external mechanical influences.

Abstract: A pendulum roller head for a resistance seam-welding machine is described, having a sliding contact current transmission device between a stator and a rotor, which device is composed of an annular disc which extends radially between rotor and stator, is fastened by its outer circumference to the stator, carries an axial sliding contact ring on its inner circumference, and is flexibly designed in its bridging part between the inner and outer circumferences. The sliding contact disc is composed of a copper braid to which the axial sliding contact ring is fastened. The sliding contact current transmission device in the form of the disc with a flexible bridging part replaces the current transmission device in the form of fluid metal which has formerly been in use in pendulum roller heads.

Abstract: A rupturable can member (10) of sheet metal has a pair of scorings (16) which define a tearing strip (18) laterally. Welded onto the tearing strip (18) is a tongue (20) which has a thickened portion (24) at its welded-on end (22). This thickened portion is formed by a margin folded back towards the other free end (26) of the tongue (20).

Abstract: What is described is an electrode wire (20) which, in contrast to conventional electrode wire (10), is provided with flanges (30,31) formed on it to support it on the circumference of a roller electrode (12) at both sides of a guide groove (22,22'). The electrode wire (20) is broader than its contrast area on the work being welded and has a considerably broader contact area on the work being welded than the conventional electrode wire. As a result, metal sheets (for example lead-coated metal sheets of fuel tanks) are pressed together alongside the weld nugget as a result of which gaping apart of the sheets alongside the weld nugget and lateral tearing of the weld nugget are prevented. The profile of the electrode wire (20) projecting beyond the guide groove (22,22') is very thin and cannot be deformed laterally under transverse forces even if the electrode wire becomes soft during the welding.

Abstract: A rupturable can member (10) of sheet metal has a pair of scorings (16) which define a tearing strip (18) laterally. Welded onto the tearing strip (18) is a tongue (20) which has a thickened portion (24) at its welded-on end (22). This thickened portion is formed by a margin folded back towards the other free end (26) of the tongue (20).

Abstract: The contact wire (30) for a roller seam welding machine is provided on its front face with grooves (32) which are formed in the longitudinal direction of the wire and which are bounded by sharp longitudinal edges (34). The contact wire (30) is particularly well suited for welding metal sheets, the surfaces of which are heavily soiled or provided with coatings which are poor electrical conductors or electrically non-conducting. During the welding operation, the longitudinal edges (34) cut open the sheets to be welded or their oxide layer or coating which is a poor electrical conductor or non-conducting, and render possible a direct passage of the welding current to the actual metal sheet. Dirt as well as semi-plastic and vaporized coating material are reliably carried away to the front and rear in the longitudinal grooves so that the contact wire (30) cannot "float" during the welding operation.

Abstract: For connecting a round hollow member (10) of sheet metal tightly to a complementary inner member (12), a force fit is produced in a narrow annular region (25) between these two members (10, 12). Then at least two electrodes (90) are applied to the hollow member (10) from the outside in the annular region and during relative rotation between the electrodes (90) on the one hand and the two members (10, 12) on the other hand, electrical resistance welding is carried out during which the welding current (I) is supplied and drawn off exclusively through the electrodes (90) bearing externally against the hollow member (10).

Abstract: A can body is rolled from a sheet-metal blank (28) and has outer and inner longitudinal edges (12 and 14 respectively) which are welded to one another in an overlapping manner. Extending round the can body transversely to the longitudinal edges (12, 14) are two circumferential scorings (16) which define a tearing strip (18) laterally. The tearing strip (18) is extended by a tongue (20) which is welded onto the outer longitudinal edge (12) and which can be gripped by a key and rolled up. In a welding zone (42) which is adjacent to a starting scoring (30), the tearing strip (18) is stiffened by the welded-on tongue (20) in such a manner that it tears away from the can body reliably along the circumferential scorings (16) during the rolling up of the tongue (20).

Abstract: A rupturable can member (10) of sheet metal has a pair of scorings (16) which define a tearing strip (18) laterally. Welded onto the tearing strip (18) is a tongue (20), which has a thickened portion (24) at its welded-on end (22). This thickened portion is formed by a margin folded back towards the other free end (26) of the tongue (20).

Abstract: The can member (10) is provided with a pair of scorings (16) which define a tear-off strip (18) laterally. A tongue (20) produced as a separate sheet-metal part is welded onto the tear-off strip (18) in a welding zone (42) at one of its ends. Between the welding zone (42) and the free end (32) of the tongue (20), a starting scoring (30) extends over the tear-off strip (18) to within the vicinity of the two lateral scorings (16). The starting scoring (30) is part of a field (28) of a plurality of scorings formed on the tear-off strip (18) below the tongue (20). The welding zone (42) partially covers over this field (28). As a result, care is taken to ensure that a tearing open operation can be reliably initiated by rolling up the tongue, substantially regardless of inaccuracies in manufacture.

Abstract: A can body is rolled from a sheet-metal blank (28) and has outer and inner longitudinal edges (12 and 14 respectively) which are welded to one another in an overlapping manner. Extending round the can body transversely to the longitudinal edges (12, 14) are two circumferential scorings (16) which define a tearing strip (18) laterally. The tearing strip (18) is extended by a tongue (20) which is welded onto the outer longitudinal edge (12) and which can be gripped by a key and rolled up. In a welding zone (42) which is adjacent to a starting scoring (30), the tearing strip (18) is stiffened by the welded-on tongue (20) in such a manner that it tears away from the can body reliably along the circumferential scorings (16) during the rolling up of the tongue (20).

Abstract: Spot- and projection-welding of aluminum sheets has always been connected with difficulties mainly because of the surface layers of aluminum oxide, and even by pickling, these difficulties could be only partly eliminated. The main difficulties have always been insufficient electrode life times, the unsatisfactory quality of the weld and especially the unsolved problem of achieving good quality welding and long electrode-life when using un-pretreated aluminum sheets. The problem has been solved in principle by using electrodes having profiled contact-surfaces, by means of which the layer of oxide is broken during pre-pressing and a direct contact between the electrode and unoxidized material of the workpiece is provided, the contact-resistance of which is lower than the portion of the overall resistance of the point of weld formed by the metal of the aluminum sheets to be welded together.