Abstract: Provided is a seam welding device capable of seam welding various shapes of objects to be welded. A seam welding device which performs seam welding by causing electricity to be conducted between a first electrode wheel and a second electrode wheel comprises a first motor which drives the first electrode wheel, a second motor which drives the second electrode wheel, and a first belt provided between the first electrode wheel and the first motor. If a direction joining the axes of the first electrode wheel and the second electrode wheel is defined as a vertical direction, the direction from the first electrode wheel toward the second electrode wheel is upward, and the direction from the second electrode wheel toward the first electrode wheel is downward, then the first motor is disposed further upward than a point of contact of the first electrode wheel and the second electrode wheel.

Abstract: A system may include a current source; a first metal or alloy component with a first major surface electrically coupled to the current source; a second metal or alloy component with a second major surface electrically coupled to the current source; a metal or alloy powder disposed in at least a portion of the joint region; and a controller. The first and second major surfaces may be positioned adjacent to each other to define a joint region. The controller may be configured to cause the current source to output an alternating current that passes from the first component, through at least a portion of the metal or alloy powder, into the second component. The frequency of the alternating current may be configured to cause standing electromagnetic waves within at least a portion of the particles of the metal or alloy powder.

Abstract: A system may include a current source; a first metal or alloy component with a first major surface electrically coupled to the current source; a second metal or alloy component with a second major surface electrically coupled in series to the first component and the current source via an external electrical conductor, where the first and second major surfaces are positioned adjacent to each other to define a joint region; a metal or alloy powder disposed in at least a portion of the joint region; and a controller. The controller may be configured to cause the current source to output an alternating current that conducts through the first component and the second component to induce magnetic eddy currents, magnetic hysteresis, or both within at least a portion of the metal or alloy powder disposed in at least the first portion of the joint region.

Abstract: A method for the connection of components or component regions and a non-releasable connection produced in this manner. Two connection faces are partially welded to each other with an adhesive layer being incorporated between the two connection faces. The method including the following steps: arranging a welding base on a connection face, applying the adhesive layer to a connection face, moving the connection faces toward each other in such a manner that the welding base is applied against the other connection face, introducing welding current in the region of the applied welding base. A spacer is arranged between the connection faces before the connection faces are moved toward each other. The connection faces are spaced apart from each other in the region of the welding base by the extent that the welding base projects above the spacer.

Abstract: A seam welding system includes a pair of roller electrodes. The pair of roller electrodes hold a to-be-welded object between circumferential surfaces of the roller electrodes, rotate while holding the to-be-welded object between the circumferential surfaces, and perform seam welding on the to-be-welded object when a current flows between the roller electrodes while rotating and holding the to-be-welded object between the circumferential surfaces. To an electrode movement mechanism, the roller electrodes are mounted. The electrode movement mechanism moves the roller electrodes along a welding line of the to-be-welded object. Drive sources respectively rotate the roller electrodes and a joint of the electrode movement mechanism. A controller controls an amount by which the roller electrodes rotate based on a torque change in the drive sources so as to keep torques respectively acting on the roller electrodes within a predetermined range.

Abstract: A current applying apparatus includes a pair of electrodes configured to contact a workpiece to apply an electric current to the workpiece, and a bus bar arranged to extend along the workpiece. At least one of the electrodes includes a moving electrode configured to move relative to the bus bar and the workpiece such that an electric current flows between the bus bar and the workpiece through the moving electrode, the moving electrode being connected to the bus bar so as to be movable relative to the bus bar, and the moving electrode being configured to contact the workpiece so as to be movable relative to the workpiece.

Abstract: With a roller head (10) of a resistance seam welding machine, which roller head has a stator (12) and a rotor (14), the bearing outer housing (18, 18?) is cooled by means of channels (2, 2?) provided in its interior. This increases the life of the roller head.

Abstract: An apparatus for manufacturing wire wrapped screens utilizing a wire and support ribs is provided. The apparatus employs welding pressure control, utilizing a welding device mounted on a support assembly, wherein the support assembly is moveable in relation to a mounting structure and the wire and support rib weld pieces. Welding pressure is determined by a force measurement device, and a control and feedback system adjusts pressure. Mechanical actuator cylinders mounted on the support assembly and the mounting structure provide load balance. A method for making wire wrapped screens is also provided.

Abstract: A method is provided for the projection electric resistance welding of a component to a laminated metal member. The laminated metal member is comprised of top and bottom metal sheets adhered together by a polymer layer provided between the top and bottom metal sheets. A plurality of projections is provided on the component and the projections extend toward the top metal sheet of the laminated metal. Force is applied to the component and the projections have a pointed shape so that the projections pierce through the top metal sheet and contact the bottom metal sheet. Weld current is then applied to flow through the projections so that the projections are electric resistance welded to both the top and bottom metal sheets.

Abstract: A method is provided for adhesively bonding together a pair of metal sheets to form a laminated sheet metal assembly. A coating of heat curable adhesive is placed on the bottom sheet. The top sheet is placed on top of the coating of adhesive. The stacked metal sheets are then placed between a pair of electrodes. One of the electrodes has a pointed projection that pierces through at least the adjacent sheet and into the adhesive. Electrical current is then conducted between the electrodes so that current flows through the projection to create electric resistance heating and thereby cure the adhesive. The electrodes can be rotating rollers and the metal sheets are fed between the rollers. The electrodes can provide heating and curing of the adhesive in a spot surrounding the pointed electrode and then the remaining uncured adhesive can be cured during later heating of the laminated assembly.

Abstract: In a welding apparatus for the longitudinal seam welding of can bodies (31?) by way of electrode rollers (8, 17), three drive stages (4, 10, 20), by means of which the wire electrode (25) is driven in addition to the drive by the electrode rollers (8, 17), are provided in the wire course. Preferably, elastic stretching is brought about in this case by the three drive stages (4, 10, 20).

Abstract: Devices and methods are contemplated in which a first electrode is circumferentially movable about a second electrode such that a tubular work piece can be resistance welded to a second work piece. Most preferably, the first electrode is a wheel-shaped electrode, while the second electrode is static and disk-shaped.

Abstract: In order to evaluate the welding current for the resistance seam welding of an overlap seam of container bodies, a welding with changing welding current intensity is carried out for a container body of the production series, resulting in a changing welding of the seam, ranging from the welding with a too high temperature to the welding with a too low temperature. The electric energy for this welding is determined several times during this welding and/or the temperature of the weld seam is determined several times and the welding current intensity is determined at which the welding of the individual container body is too cold and the welding current intensity at which the welding is too hot. This determination is based on the determined electric energy values and/or on the determined temperature values and based on this determination a preferred range for the welding current intensity within these limits of too hot and too cold is determined.

Abstract: A pair of upper and lower pressure rollers 3, 4 is disposed so that their axes 15, 16 are tilted in a horizontal plane in respective directions opposite to each other with respect to a straight line perpendicular to a welding line of a joint portion J. The pressure rollers 3, 4 are positively driven by corresponding electric motors 63, 64 to thereby roll the joint portion. Thus, steps defined at the joint portion can be smoothed and a step gradient can be reduced to ensure a high degree of joint strength.

Abstract: In order to evaluate the welding current for the resistance seam welding of an overlap seam of container bodies, a welding with changing welding current intensity is carried out for a container body of the production series, resulting in a changing welding of the seam, ranging from the welding with a too high temperature to the welding with a too low temperature. The electric energy for this welding is determined several times during this welding and/or the temperature of the weld seam is determined several times and the welding current intensity is determined at which the welding of the individual container body is too cold and the welding current intensity at which the welding is too hot. This determination is based on the determined electric energy values and/or on the determined temperature values and based on this determination a preferred range for the welding current intensity within these limits of too hot and too cold is determined.

Abstract: An improved fusion welding system having a heating unit and welding device is adapted for increasing the efficiency of welding a plurality of workpieces. The system preferably presents a single-sided process, and includes first and second electrode wheels operable to heat a portion of the workpieces to a minimum temperature, and a translatable laser cooperatively configured to form a continuous weld within the heated portion. The preferred system provides the advantages of laser welding, such as precision, while enabling weld production at lower laser power outputs or faster welding speeds than conventional laser welding systems.

Abstract: This manufacturing method of a fuel tank is for manufacturing a metallic fuel tank having a concavo-convex portion in a course of seam welding using a seam welder, wherein the seam welding is performed using the seam welder provided with a non-interfering space where interference with the fuel tank is avoided, while changing the position of the fuel tank relative to the seam welder.

Abstract: An apparatus for manufacturing a wire wound filter screen from wrapping wrap wire over a set of rib wires has a frame, a spindle for supporting the rib wires in a longitudinal orientation, a wire guide for delivering wrap wire around the rib wires as the spindle rotates the rib wires, an electrode for welding the wrap wires to the rib wires at each intersection thereof, and a translating mechanism positioned on the frame for moving rib wires and the welded wrap wire longitudinal along the frame. A laser measures a gap between adjacent surfaces of wrap wire. A processor is used to adjust the translating of the rib wires relative to the gap. An air cushion urges the electrode against the wrap wire.

Abstract: Where can bodies of sheet metal are welded between the welding rollers of a welding machine, the welding current is not applied to the welding rollers until the body is between the welding electrode rollers. In this way, the quality of the weld at the initial weld point is improved, and where intermediate wire electrodes are used, wire breaks are reliably prevented.

Abstract: In response to the recent various requests, the present invention provides a method for manufacturing filler neck to facilitate jointing a mouthpiece and a feeding pipe which were manufactured separately into an integrated filler neck having an excellent hermeticity. The method for manufacturing a filler neck 1 comprises the following steps: jointing an inner face of the circumferential wall portion 16 of a feeding pipe and an outer face of the circumferential wall portion 12 of the mouthpiece, and integrating with the mouthpiece 2 and the feeding pipe 3, wherein the outer of the mouthpiece and the inner face of the feeding pipe are in relation to be fitted in a press-fitted condition, a seam welding is executed to the welding area W provided in a range of the overlapped area S defined by the width of the circumferential wall portions.

Abstract: In a battery post burning apparatus, the majority of the heat is supplied to the lead via the mold in which the finished post is being formed. The mold material in contact with the lead has a low thermal mass and high electrical and thermal resistance. The mold material may be Meehanite cast iron. Another material, such as titanium, may be used. If so, it is preferable to coat it with silver solder and provide a copper insert, where the electrical and thermal connection is being made. In another embodiment, a magnetic field is provided to break up any oxide coatings on the mold surfaces.

Abstract: A rolling head for a resistance seam welding machine comprises a stator; an annular electrode constituting the rotor rotatably mounted on the stator; a device for conducting electricity through a sliding contact, positioned between the stator and the rotor and pressed in axial direction against at least one of them by an elastic force; and conduits through which a coolant flows in the stator, in the rotor and in the sliding contact conductive device. The electrical conductive device comprises elastically yielding elements, forming a radial effect sector shaped and/or made in various different ways, positioned between the stator and the rotor and designed to remain permanently in contact with the stator and the rotor so as to conduct electrical current from one to the other.

Abstract: Where can bodies of sheet metal are welded between the welding rollers of a welding machine, the welding current is not applied to the welding rollers until the body is between the welding electrode rollers. In this way, the quality of the weld at the initial weld point is improved, and where intermediate wire electrodes are used, wire breaks are reliably prevented.

Abstract: A welding device has two mutually engaging welding wheels, together with a separating device having a blade with a cutting edge. Two film webs can be welded together in conventional manner using the welding device. The blade is able to separate a projecting length from the welded film, the blade being heated. Heating takes place by a heat bridge, which connects the blade to a heater of the welding device. This economizes a separate heater for the blade.

Abstract: This invention provides an improved method of projection welding which enables the sound welding of high-carbon, and high-tension low-alloy steels. A spacer is disposed between two parts to be joined by projection welding. At least one of the parts is made of a high-carbon, or high-tension low-alloy steel. The spacer is a thin sheet, or coating formed on at least one of those parts.

Abstract: A rolling head for a resistance seam welding machine comprises a stator; an annular electrode constituting the rotor rotatably mounted on the stator; a device for conducting electricity through a sliding contact, positioned between the stator and the rotor and pressed in axial direction against at least one of them by an elastic force; and conduits through which a coolant flows in the stator, in the rotor and in the sliding contact conductive device. The electrical conductive device comprises elastically yielding elements, forming a radial effect sector shaped and/or made in various different ways, positioned between the stator and the rotor and designed to remain permanently in contact with the stator and the rotor so as to conduct electrical current from one to the other.

Abstract: In a rolled seam welding machine which can be fed from the front for producing a lap seam, the welding roller which is disposed in front of the Z rail can be swung away in order to facilitate automatic feeding of the welding stock into the Z rail.

Abstract: The present invention provides a method for hermetically sealing a semiconductor laser element, by which the cleanness of a package can be maintained extremely satisfactorily in a stabilized state, in order to prevent organic substances from being adhered to the end faces of high output semiconductor laser elements due to photochemical actions. The method comprises the first step of introducing oxygen into a chamber of a hermetical-sealing apparatus and irradiating ultraviolet rays onto an unsealed package having a semiconductor laser element mounted, in the chamber, and the second step of purging the chamber with an inert gas and hermetically sealing an unsealed package in the inert gas atmosphere without being exposed to the outer atmosphere.

Abstract: A seam welding apparatus having an improved bearing support arrangement for the transversely movable upper weld wheel. This upper weld wheel is nonrotatably secured adjacent one end of an elongate electrically conductive shaft, which shaft adjacent its other end is supported within a conventional electrically conductive bearing assembly which rotatably supports the shaft and transmits electrical energy thereto from an external source such as a transformer. The nonrotatable housing associated with the bearing assembly is pivotally supported relative to the machine frame by a pivot which extends adjacent the housing in perpendicular relation to the shaft axis, with this pivot axis being disposed remote from the weld wheel. A welding force generating assembly such as a pressure cylinder and ram are mounted on the machine frame, with the ram being movably supported and acting downwardly onto a spring unit which has an electrical insulator associated therewith.

Abstract: To weld a workpiece rounded from plane metal sheet on a seam welding machine, the workpiece is introduced into a preform (7) whose internal shape is approximately the same as the workpiece. Stops (11, 12, 14) are used to fix the workpiece in place in the preform, and the workpiece is then moved together with the preform (7) towards the welding rollers and welded. To this end the preform (7) is arranged on a platform (6) which in its turn is arranged on a movable carriage (3) in the welding machine (1). Welding with the preform makes it possible to weld together any desired sheet metal workpieces, including those which are not uniformly rounded because, for example, they are formed from blanks incorporating recesses.

Abstract: A plurality of pistons are disposed in series in a circular electrode pressure cylinder and each of the pistons is separated. During low pressure output only one piston is used so that the friction force of the other pistons is not transmitted.

Abstract: An automatic machine for rapidly fabricating a continuous length of metallic honeycomb core having a finite width and a precise height for use, substantially as fabricated, in bonding in a honeycomb core panel structure from a continuous strip of preformed metal foil having spaced crest and trough sections. The machine includes a fixed central foil guide that directs a continuous strip of metallic foil to a horizontally translatable guide that positions the foil strip between two banks of vertically biased banks of individual weld blocks having sets of vertically disposed weld pin electrodes. A spreader carriage that is horizontally translatable in synchronism with the translatable guide momentarily spreads individual opposed biased weld blocks to permit the foil strip to be laid against a previously received portion of such foil strip in horizontal and vertical registry of the crests and troughs of the preformed strip.

Abstract: In a welding electrode protecting machine, welding electrodes are protected against a surface treating agent on strips to be welded by applying a proper amount of electrode protecting agent onto surfaces of welding electrodes prior to or during welding operation.

Abstract: For welding sheet-metal blanks coated with electrically conductive material, the thickness of the coating is measured with a measurement device. The welding current source controls the welding current I as a function of the film thickness reading obtained, to keep the power input into the weld zone essentially constant.

Abstract: A robot for welding motor-vehicle bodies or subassemblies thereof is provided with a head for carrying out wire resistance seam weldings. The welding head includes a pair of counter-rotating welding rollers through which an electric current is passed. A copper wire is fed continuously around the welding rollers.

Abstract: Mash seam welding process and apparatus, wherein two plate-like workpieces having different thickness values are fed and guided by a guiding device such that a length W.sub.H of contact of the thick plate-like workpiece with one of two roller electrodes is smaller than a length W.sub.M of contact of the thin plate-like workpiece with the other roller electrode. In this arrangement, the amount of mashing of the thick plate-like workpiece by the roller electrode is made larger than that of the thin plate-like workpiece by the other roller electrode, so that an interface of the two plate-like workpieces is positioned intermediate between the pair of roller electrodes, whereby a weld nugget formed intermediate between the roller electrodes extends across the interface, permitting the weld to have a sufficient strength owing to a nugget ratio, which is a ratio of a width dimension W.sub.N of the weld nugget in the direction of the interface to a width dimension W.sub.G of the interface.

Abstract: A method and apparatus for automatically welding and handling welded tailored blank composites. The method comprises the steps of transferring first and second sheet component parts from respective input stacks to an assembly table of a welding machine. The sheet components are disposed in a butt joint or an overlapping lap joint configuration and the blanks are welded together along a weld seam thus defining a welded blank. The welded blank is conveyed in a timed step manner from the welding machine to an output stacking machine via a magnetic stepping conveyor and the blank is transferred from the conveyor to an output stack of completed blanks with a stacking machine. An apparatus is provided to carry out the method.

Abstract: A novel method and apparatus is disclosed for the production of single plane ladder-type rack strip material in which wire cross bar elements are Tee-welded to the inside surface portions of opposed, parallel side elements formed of similar wire material. The welding procedure involves contacting the cross bar element centrally with an electrode of a first polarity and contacting the wire side elements on opposite sides with electrodes of a second polarity. During the welding operation, current flows substantially equally from the first electrode in opposite directions through the opposite weld interfaces to the opposed second electrodes. By observing physical symmetry in the electrical supply at opposite sides, equalization of current flow is optimized so that the emerging rack strip product is flat and straight, suitable for commercial marketing.

Abstract: An electric resistance welder welds, hot reduces, tempers and planishes overlapped metal workpieces. The welder incorporates two transformers (50, 60) which are connected to two sets of wheel electrodes (26, 28 and 36, 38). Electric current from a first transformer (50) flows through workpieces (16) and returns through a second transformer (60). The first set of wheel electrodes (26, 28) creates a weld joint and the second set (36, 38), depending on the shape, area, and pressure of the wheels, either reduces the weld thickness, tempers the weld joint, or both. A control circuit (72) includes a current sensor (70) and power factor adjuster (80). The current sensor senses current flow through the first transformer during the welding process. As the current changes, particularly when the sets of wheel electrodes engage and disengage the workpieces, the power factor adjuster (72) adjusts the power factor to maintain constant heat to the workpieces.

Abstract: A method and apparatus for automatically welding and handling mash welded tailored blank composites. The method comprises the steps of transferring first and second sheet component parts from respective input stacks to an assembly table of a mash welding machine. The sheet components are disposed in an overlapping lap joint configuration and the lap joint is welded along a linear weld seam thus defining a welded blank. The welded blank is conveyed in a timed step manner from the welding machine to an output stacking machine via a magnetic stepping conveyor and the blank is transferred from the conveyor to an output stack of completed blanks with a stacking machine. An apparatus is provided to carry out the method.

Abstract: Two pieces of steel strip are welded together by a method employing projection resistance welding. A portion of one strip is formed with a series of aligned projections and arranged in superimposed relation with a portion of the other strip. The superimposed portions are moved through a welding zone located between upper and lower electrodes, typically a pair of rotatable welding wheels, through which a continuous electrical current flows. As the projections move into and through the welding zone, they are heated, flattened, melted and welded to the other of the two superimposed portions. The projections may be in the form of a continuous, elongated ridge (when the steel strips are uncoated) or in the form of spaced apart dimples (when the steel strips are coated or uncoated).

Abstract: A relatively simple and inexpensive apparatus and method for providing high quality and aesthetically pleasing continuous resistance welded hollow metal articles at constant speed comprises an article workpiece conveying guide means for guiding the article workpiece through a welding means under controlled, stable, vibration free conditions in a predetermined path. The path has linear and non-linear portions. A sensor interactively connected to a programmable controller which functions to move the workpiece quickly and accurately through the welding means under stable conditions at a high uniform rate of speed. A first guide provides a weld edge reference guide, and a simple pivotal tracking system provides a weld path guide during non-linear travel of the workpiece. The tracking system exerts its force on the workpiece generally through the center of percussion of the article workpiece whereby no vibration is imparted by the force to the workpiece.

Abstract: A roller seam welding machine is provided with a contour-controlled table for the tank to be welded. The table is driven by a pinion (4) and a pantograph (16), in a known manner. To enable flanges (6) with a three-dimensional profile to be welded, the welding rollers (10,11) are mounted on a vertically traversable head (14) of the machine. This allows the welding rollers to be traversed to suit rises or falls in the welding flange (6). Because the tank itself is manipulated only in a horizontal plane in the conventional manner, with vertical manipulation of the welding rollers as an additional feature, the possibility is afforded in a simple manner of welding tank flanges with three-dimensional profiles with high precision irrespective of the weight and size of the tank.

Abstract: Methods and device for the electric welding of at least two sheets of multilayer structure (2,5), termed sandwich sheets, each including at least two metal sheets interconnected by a film of polymer. The method includes putting the inner faces (3a, 7a) of the sandwich sheets (2,5) into contact in a partial overlapping region, applying on the opposite faces (4a, 6a) of the sandwich sheets at least two rollers each having two parts and placed in confronting relation to each other in alignment with the overlapping region, supplying electric power to at least the second part of each roller (9,10), exerting a clamping force on the overlapping region of the sandwich sheets (2,5) using the rollers so as to bring the second part of each of the rollers into contact with the inner face of the confronting sandwich sheet and shifting the rollers (9,10) along the overlapping region.

Abstract: The measurement of the voltage over the welding point in order to supervise the welding quality takes place by means of voltage taps on the wire electrodes. As a result, the additional parasitic resistances during measurement by means of conventional voltage taps on the roller head or the roller head mounting are completely eliminated, which improves the measuring accuracy.

Abstract: The seam welding machine with welding arrangement 10 has a lower part (1) and an upper (2). Load-bearing components are upper and lower longitudinal girders (20, 21) with a rigid connection (3, 4) between them. For clamping sheet blanks (7, 8) for welding, two clamping blocks are provided, each with upper and lower pressure beams (24, 25); at least the upper pressure beams (24) can be raised and lowered by means of jacks. For longitudinal transport of workpieces (7, 8) along the weld axis (Z), each beam has a feed unit (40, 41). Each feed unit comprises a longitudinal guide extending in the direction of the axis (Z), a slide, with clamping devices, guided on this longitudinal guide, and a reversible linear drive connected to the slide.

Abstract: The invention is related to an apparatus for re-using a copper wire having been used once for mash seam welding in a mash seam welder for mash seam welding a lap formed by overlapped opposite side edges of a metal sheet or like blank between upper and lower roller electrodes via copper wires. The apparatus is provided in a portion of or in relation to the mash seam welder for taking up the copper wire having been used once for welding and squeezed to have a substantially flat sectional profile as taken-up wire and feeding again the taken-up wire as rewound wire to the mash seam welder to be used again for welding between said upper and lower roller electrodes.

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: Mash seam welding process and apparatus, wherein two plate-like workpieces having different thickness values are fed and guided by a guiding device such that a length W.sub.H of contact of the thick plate-like workpiece with one of two roller electrodes is smaller than a length W.sub.M of contact of the thin plate-like workpiece with the other roller electrode. In this arrangement, the amount of mashing of the thick plate-like workpiece by the roller electrode is made larger than that of the thin plate-like workpiece by the other roller electrode, so that an interface of the two plate-like workpieces is positioned intermediate between the pair of roller electrodes, whereby a weld nugget formed intermediate between the roller electrodes extends across the interface, permitting the weld to have a sufficient strength owing to a nugget ratio, which is a ratio of a width dimension W.sub.N of the weld nugget in the direction of the interface to a width dimension W.sub.G of the interface.