Abstract: A joined assembly includes: a first member; a second member which has a facing part facing the first member in a thickness direction thereof; and joints lying along the facing part to join the first member and the second member to each other. The joints include: a pair of end joints respectively located at the opposite end portions of the facing part; and an intermediate joint located between the end joints and having a lower joining strength than the end joints. The end joint includes a fastening member mechanically joining the first member and the second member. The intermediate joint includes a friction-stirred part joining the first member and the second member by friction stir.

Abstract: A friction stir spot welder includes a controller configured to: drive a rotary actuator and an advancement/withdrawal actuator to cause a pin to press workpieces while rotating; after the pressing, drive the rotary actuator and the advancement/withdrawal actuator to cause the pin and a shoulder to press the workpieces while rotating; and after the pressing, drive the rotary actuator and the advancement/withdrawal actuator to cause the pin and/or the shoulder to plunge into a weld region of the workpieces while rotating and stir the weld region to weld the workpieces together.

Abstract: A friction stir welding tool and method, by which influence on durability of the tool is suppressed even when resistance force generated when the tool moves for joining acts on facing end portions of workpieces which are located close to an attachment side of the tool. The tool includes: a stirring shaft; a first shoulder portion provided to be unrotatable relative to the shaft and configured to rotate together with the shaft when it rotates; a second shoulder portion provided to be unrotatable relative to the shaft and configured to rotate together with the shaft when it rotates; and a third shoulder portion attached around the shaft located between the first and second shoulder portions, and includes an inclination preventing portion to prevent inclination of the shaft by contacting the workpieces to receive reaction force from the workpieces when the shaft is made to move along joining lines.

Abstract: A double-acting tool for friction stir spot welding is used to weld a first member and a second member each formed of a thermoplastic resin molding by friction stir spot welding. An overlapping part of the first member and the second member is formed, and the tool is disposed against the overlapping part while rotating a pin and a shoulder about a rotation axis. The shoulder is plunged into the overlapping part to start friction stir. The plunging is continued until the shoulder penetrates the first member, and penetrates the second member or reaches a depth corresponding to a first thickness t1 or lager. Subsequently, the overlapping part is backfilled with a resin material overflowed due to the plunging.

Abstract: A first member formed of a thermoplastic resin molding mixed with a fiber material and a second member formed of a molding containing at least a thermoplastic resin are welded by friction stir spot welding using a double-acting tool for friction stir spot welding. An overlapping part between the first member and the second member is formed, and the tool is disposed against the overlapping part while the pin and the shoulder are rotated about the rotation axis. The pin is plunged into the overlapping part, and friction stir is performed to cause extension fibers to remain around a plunging region of the pin while the shoulder is retracted to release an overflow material. The shoulder is brought closer to the overlapping part to wrap the extension fibers into the overflow material when the overflow material is backfilled while the pin is retracted from the overlapping part.

Abstract: A friction stir spot welding apparatus includes: a pin that is columnar; a shoulder that is cylindrical, the pin being within the shoulder; a rotary driver that rotates the pin and the shoulder about an axis that coincides with a center axis of the pin; and an advance-retreat driver that advances and retreats the pin and the shoulder along the axis. A first groove is formed at a tip end portion of an outer peripheral surface of the shoulder so as to extend in a direction along the center axis of the pin.

Abstract: A friction stir spot welder includes a controller configured to: drive a rotary actuator and an advancement/withdrawal actuator to cause a pin to press workpieces while rotating; after the pressing, drive the rotary actuator and the advancement/withdrawal actuator to cause the pin and a shoulder to press the workpieces while rotating; and after the pressing, drive the rotary actuator and the advancement/withdrawal actuator to cause the pin and/or the shoulder to plunge into a weld region of the workpieces while rotating and stir the weld region to weld the workpieces together.

Abstract: A friction stir welding tool and method, by which influence on durability of the tool is suppressed even when resistance force generated when the tool moves for joining acts on facing end portions of workpieces which are located close to an attachment side of the tool. The tool includes: a stirring shaft; a first shoulder portion provided to be unrotatable relative to the shaft and configured to rotate together with the shaft when it rotates; a second shoulder portion provided to be unrotatable relative to the shaft and configured to rotate together with the shaft when it rotates; and a third shoulder portion attached around the shaft located between the first and second shoulder portions, and includes an inclination preventing portion to prevent inclination of the shaft by contacting the workpieces to receive reaction force from the workpieces when the shaft is made to move along joining lines.