A sliding member integrated with a guide pin is inserted into a guide hole of an electrode main body. An elastic ring is integrated with the guide pin under a state in which the guide pin passes through the elastic ring. A portion of the sliding member has a pressurizing end surface configured to press the elastic ring against an inner end surface of the guide hole. When the pressurizing end surface presses the elastic ring against the inner end surface, flow of the cooling air is interrupted. When the elastic ring is away from the inner end surface, the cooling air is allowed to flow.

A method of resistance spot welding and a spot-welded workpiece assembly are provided. First and second metallic workpieces are provided, each having faying surfaces including interface portions. The workpieces are disposed with the interface portions of their faying interfaces spaced apart from each other by a predetermined spacing distance. A set of opposed welding electrodes including a first electrode and a second electrode are provided, the first electrode being disposed on a side of the first workpiece, and the second electrode being disposed on a side of the second workpiece. Pressure is applied to the workpieces via the weld faces of the electrodes, and the workpieces are heated via the electrodes to form a spot weld joint between the interfaces of the faying surfaces. The faying surfaces may be spaced apart with shim material, a raised or folded-over portion of a workpiece, and/or a filler material having spacing particles.

A highly corrosion-resistant spot weldment can be produced at low cost without occurrence of prominent protrusions and the like on the surface. The spot weldment is joined by a nugget formed inside stacked sheet materials through bringing a pair of electrodes arranged opposite to each other into pressure contact with the stacked sheet materials from outside and energizing the stacked sheet materials from the electrodes. The nugget has a diameter that is 4t (t: thickness of sheet material) and a flattening level of 3.5 to 8, which is a ratio of diameter to thickness. Both outer surface parts of the sheet materials are free from protrusions formed due to bulging of molten metal. Even when the electrodes are made of a copper alloy, the increased amount of Cu in the outer surface parts is 0.2 mass % or less with respect to the component composition before spot welding.

An electrode tip for resistance spot welding includes a main body with tip and base portions. The tip portion has a bottomed and substantially cylindrical shape. The base portion has a substantially cylindrical shape and merges into the tip portion. The main body is made of a copper alloy such as chromium copper. The tip portion has a bottom part and a barrel part. The bottom part has a pressure-contact surface that is not recessed with respect to a workpiece to be pressed. The barrel part has a substantially cylindrical shape and merges into the bottom part. The electrode tip may have an inner diameter ratio (inner diameter of the barrel part to an outer diameter of the base portion) of 0.4 to 0.6, and may also have a bottom thickness ratio (thickness of the bottom part to the outer diameter of the base portion) of 0.15 to 0.5.

A welding gun includes: a moving mechanism portion (ball screw mechanism) for moving a movable electrode back and forth; a motor that includes a rotor and drives the moving mechanism portion to move the movable electrode back and forth; and a brake mechanism that prevents rotation of the rotor during a braking operation, wherein the brake mechanism includes an annular brake disc that is attached to an outer peripheral surface of the rotor and rotates integrally with the rotor, and a clamping portion that prevents rotation of the brake disc by clamping the brake disc during the braking operation.

An electrode moving mechanism of a welding gun includes a first mechanism portion that has a shaft, a second mechanism portion that has a housing capable of housing at least a portion of the shaft, and supports the shaft in a manner to be relatively movable in an axial direction, and a cover member that covers at least a portion of the shaft and is capable of expanding and contracting in accordance with relative displacement between the first mechanism portion and the second mechanism portion, wherein a communication path is formed that enables communication between an internal space, which is between the shaft and the cover member, and an internal space of the housing.

A method of manufacturing a resistance weld in at least three overlying sheet metal layers includes the steps of: (1) providing a first sheet metal layer having a first thickness; (2) providing a second sheet metal layer having a second thickness; (3) providing a filler material on the second sheet metal layer; (4) providing a third sheet metal layer having a third thickness onto the filler material and the second sheet metal layer wherein the third thickness is less than each of the first and the second thicknesses; (5) pressing a pair of welding electrodes against a pair of opposing outer surfaces with the filler material disposed therebetween; and (6) passing an electric current between the pair of electrodes through the filler material and the first, second, and third sheet metal layers to form a weld nugget which penetrates into at least the first and second sheet metal layers.

A component loading-welding system for welding a component panel to a vehicle body panel includes a rotation portion body having first and second opposing sides. The first opposing side is coupled to a robot arm. A picking device is installed in the rotation portion body and is configured to hold and release the component panel. A vehicle body pressurizing tip is installed in the rotation portion body. A pressurizing portion body is rotatably installed at the second opposing side of the rotation portion body. A pin clamp is installed in the pressurizing portion body and is configured to clamp the component panel. A component pressurizing tip is installed in the pressurizing portion body and is configured to apply pressure to the component panel. A multi point projection welding method is also disclosed.

An electrode unit of a joining apparatus includes an abutting section provided with a tapered outer circumferential surface that contacts a tapered pressure-receiving surface by being inserted into an inside of a first metal member. The tapered outer circumferential surface inclines in a direction of getting closer to an axial center of the abutting section from one end side to another end side. At least part of the abutting section has a thickness elastically deformable in such a manner that the tapered outer circumferential surface aligns with the tapered pressure-receiving surface during application of a pressurizing force to the first metal member and a second metal member.

A joining apparatus includes an electrifying/pressurizing head provided with an abutting surface contacting a pressure-receiving surface of a first metal member, joins the first metal member and a second metal member by electrification and pressurization employing the electrifying/pressurizing head, and obtains a joined body in which a joining interface inclines with respect to the pressure-receiving surface. The abutting surface includes: an electrode section capable of electrifying the first metal member; and an insulating section configured from an insulating material. At least a shortest portion where a distance from the joining interface will be shortest, of the pressure-receiving surface will be a non-contact-with-electrode section of non-contact with the electrode section, and the insulating section contacts at least part of the non-contact-with-electrode section.