This spot welding method for an aluminum material comprises: a processing step in which, in a plan view, a circular emboss expanded in a direction of superposition on a second aluminum plate side is formed at a position-to-be-welded of a first aluminum plate; an arrangement step in which positions-to-be-welded are superimposed while the expansion side of the emboss faces the second aluminum plate, and the positions-to-be-welded are arranged between a pair of electrodes; a pressing step in which the superimposed aluminum plates are pinched between the electrodes, and a central side excluding a peripheral edge of the emboss is pressed; and an electrification step of performing pressing and electrification. An electrode having a tip diameter larger than the diameter of a root part of the expansion part of the emboss is used.

A welding assembly may include a current generator, a first electrode electrically coupled to the current generator, the first electrode including a first engagement surface, a second electrode electrically coupled to the current generator, the second electrode including a second engagement surface and a width-determining fixture positioned between the first electrode and the second electrode to define a welding volume.

A workpiece stack-up that includes at least a steel workpiece and an adjacent and overlapping aluminum workpiece can be resistance spot welded by a multi-stage spot welding method. The multi-stage spot welding method involves initially forming a weld joint between the steel and aluminum workpieces. The weld joint extends into the aluminum workpiece from the faying interface of the two workpieces and includes an interfacial weld bond area adjacent to and joined with the faying surface of the steel workpiece. After the weld joint is initially formed, the multi-stage spot welding method calls for remelting and resolidifying at least a portion of the weld joint that includes some or all of the interfacial weld bond area. At least a portion of the resultant refined weld joint may then be subjected to the same remelting and resolidifying practice, if desired. Multiple additional practices of remelting and resolidifying may be carried out.

A method for welding includes (1) assembling a workpiece comprising a first member and a second member; (2) positioning a first electrode proximate the first member and a second electrode proximate the second member, the first electrode being moveable relative to the second electrode; (3) positioning a shunt member between the first and the second electrode; (4) clamping the workpiece between the first and the second electrode; and (5) during the clamping, passing a welding current between the first and the second electrode, wherein, while the welding current is passing between the first electrode and the second electrode, the first electrode moves relative to the second electrode from at least a first position, wherein a gap is defined between the shunt member and the second electrode, to a second position, wherein the gap is closed and at least a portion of the welding current passes through the shunt member.

A flawless aluminum resistance welding system includes a welding gun that includes a gun body to engage a first welding tip and a second welding tip with an upper panel and a lower panel of an object to be welded. The welding gun further includes: a pressing actuator to press the upper panel of the object at a high pressure by the first welding tip during spot welding, a welding transformer to supply a welding current for the spot welding, an air balance cylinder to adjust an air pressure to make the second welding tip in a no-load balance state, and a linear guide unit to guide the second welding tip in up and down directions. The welding gun has an equalizing function and a bidirectional pressing structure in which the second welding tip rises with a reaction force when the first welding tip presses the upper panel.

A method for producing a secondary battery according to the present invention comprises a step wherein a negative electrode collector, which has a projection having a height of from 0.36 mm to 0.45 mm on at least one of a first member and a second member, said members constituting the negative electrode collector, is resistance-welded with a core multilayer part in such a manner that the core multilayer part is sandwiched between the first member and the second member, while having the projection in contact with the core multilayer part.

A joint structure includes a first metallic material having a first projection, a second metallic material similar to and weldable to the first metallic material, and a different material having a first penetrating part and sandwiched between the first and second metallic materials, the different material being difficult to weld to the first and second metallic materials. The first projection is smaller than the first penetrating part and is spaced from the rim of the first penetrating part. The first projection is positioned in the first penetrating part and spaced from the second metallic material by a gap. The gap has a size of a predetermined percentage of the thickness of the first projection to which arc welding is applied. The first and second metallic materials are melted and joined together inside the first penetrating part to compress and fix the different material, so all three are fixed together.

Methods for resistance welding, resistance-welded assemblies, and vehicles including resistance-welded assemblies are provided. An exemplary resistance welding method includes compressing a workpiece stack-up with an interface material between first and second workpieces to squeeze a portion of the interface material to a reduced thickness. After compressing the workpiece stack-up, the first welding electrode contacts the first workpiece at an operating contact area between the first welding electrode and the first workpiece that is greater than an initial contact area. The method also includes passing an electrical current between the welding electrodes to form a molten weld pool within the workpieces, and ceasing the passing of the electrical current between the welding electrodes to allow the molten weld pool to solidify into a weld nugget that forms all or part of a weld joint between the workpieces.

Methods for resistance welding, resistance-welded assemblies, and vehicles including resistance-welded assemblies are provided. The method includes providing a workpiece stack-up including first and second workpieces and an intermediate material located between the faying surfaces thereof. At least one of the first workpiece and the second workpiece is formed of a first metal alloy with a first concentration of an alloying element, and the intermediate material is formed of a second metal alloy of the first metal and a second concentration of the alloying element that is less than the first concentration. The method includes bringing electrodes into contact with the workpieces, passing an electrical current therebetween to form a molten weld pool, and cooling the molten weld pool into a weld nugget that forms all or part of a weld joint between the workpieces and has a composition that is a mixture of the workpieces and the intermediate material.

A plurality of aluminum materials overlapped with each other are sandwiched between electrodes for spot welding. After main energization to form a nugget between the aluminum materials sandwiched between the electrodes, pulsation energization in which energization and stop of the energization are repeated a plurality of times is performed. A current value in the pulsation energization is set to be greater than a current value of the main energization, the energization and stop of the energization are repeated at least three times in the pulsation energization, and an energization stop period is increased from a first half of the pulsation energization to a second half of the pulsation energization.