A friction stir spot welding apparatus including a controller that (A) operates a rotary driver and a tool driver such that a pin and a shoulder are brought into contact with a welded workpiece; (B) operates, after the (A), the rotary driver and the tool driver such that the pin separates from the welded workpiece; and (C) operates, after the (B), the rotary driver and the tool driver such that the pin advances toward the welded workpiece. The controller controls the tool driver such that pressing force applied to the welded workpiece from the pin and the shoulder in the (C) is smaller than that in the (B) and/or controls the rotary driver such that rotational frequencies of the pin and the shoulder in the (C) are lower than those in the (B).

The present disclosure relates to a piston for an internal combustion engine. The piston comprises a cover which at least partially covers a piston basehead of the piston. A heat-isolating air gap is formed between the cover and the piston basehead, which is fluidically connected to a combustion chamber and/or an upper side of the cover facing away from the heat-isolating air gap. The fluidic connection permits a fluid exchange to take place between the heat-isolating air gap and the combustion chamber. In this way, a pressure gradient can be reduced between the combustion chamber and the heat-isolating air gap. As a result, the cover is/can be kept thin without being deformed during combustion.

A joined body includes: a main body section including a wall section forming a passage along which a medium for accelerating heat exchange flows; and a cover configured to cover a surface of the main body section, the cover including: a covering section provided on a side facing the main body section and configured to cover the surface; a groove section provided on the side facing the main body section and configured to accommodate an end portion of the wall section; and a stirred joint section provided on a side opposite to a side where the covering section and the groove section are provided, the stirred joint section being at least partly frictionally stirred by a depth reaching a bottom of the groove section from a surface on a side opposite to the side facing the main body section and bonded to the end portion of the wall section.

A friction stir welding method in which a first member to be welded and a second member to be welded and having a first step portion are welded by friction stir welding using a welding tool includes the steps of arranging the first member to be welded on a step supporting surface of the first step portion with a gap between the first member to be welded and a side surface of the first step portion, pushing the welding tool into the first member to be welded from a surface of the first member to be welded while rotating the welding tool and inserting the welding tool until reaching the step supporting surface of the second member to be welded and stirring the first member to be welded and the second member to be welded by rotating the welding tool to form a welding part.

A method of performing friction stir spot welding of a plurality of steel plates, includes the steps of: friction stirring a spot welding portion of the plurality of steel plates by pressing a tool against the spot welding portion while rotating the tool, to plasticize the spot welding portion by friction heat; cooling the spot welding portion to cause martensitic transformation to occur in the spot welding portion, after the step of friction stirring the spot welding portion; and tempering the spot welding portion by the friction heat by re-pressing the tool against the spot welding portion while rotating the tool, after the step of cooling the spot welding portion.

In order to produce a clutch pack (3), clutch plates are cut from an electrical steel strip or sheet, arranged on top of one another to form the clutch pack (3) and connected to one another within the clutch pack (3). The material of the clutch plates is locally plasticised in the edge region via the generation of frictional heat by means of at least one tool (9′), in such a way that the material of at least adjacent clutch plates is mixed with the tool (9′) such that, after the plasticised material has cooled, these clutch plates are integrally connected to one another. The device used for this purpose has at least one punch press and/or at least one receiving means for one or more clutch packs (3). In addition, the device has at least one welding tool that is rotatably driven about its axis and can be moved in a transverse direction to its rotational axis.

A friction stir spot welding method includes a welding step of forming a build-up portion on a workpiece by friction-stirring the workpiece, using a pin and a shoulder, while pressing a surface of the workpiece with an end face of a clamp, and filling a portion of the workpiece being softened in a chamber portion of the clamp by press-fitting at least one of the pin and the shoulder into a plastic flow portion of the workpiece. and the friction stir spot welding method further includes a pressing step of pressing a surface of at least one of a region of the build-up portion, which is frictionally stirred by the shoulder, and an adjacent region of the build-up portion against the end face of the clamp with the pin and the shoulder retracted into an accommodation space.

A method of forming a monolithic aircraft structure having multiple aerodynamic surfaces includes forming a body component to have a body skin defining a body skin outer surface, and a body side wall integrally formed with the body skin and defining a body mating surface, the body skin outer surface providing a first aerodynamic surface. A cover component is formed to have a cover mating surface and a cover outer surface opposite the cover mating surface, the cover outer surface defining a second aerodynamic surface. The body component is positioned relative to the cover component so that the body mating surface engages the cover mating surface. At least portions of the cover mating surface are friction stir welded to the body mating surface to form friction stir welded joints between the body component and the cover component.

A dissimilar metal welding method includes a preparing step and a working step. In the preparing step, a pin member is moved to a second metal material while being rotated, and a tool body is driven such that the tool body is moved in a direction away from the second metal material while being rotated. In the working step, a through-hole is formed in the second metal material by the pin member, and then a distal end of the pin member is dug into the first metal material to a predetermined depth position in the first metal material.

A spot welding apparatus which performs spot welding of a plurality of plate materials which are lapped to each other, comprises a displacement driving unit which displaces lapped portions of the plurality of plate materials and a tool relatively to each other; a rotation driving unit which rotates the tool; and a controller which controls the displacement driving unit and the rotation driving unit so that the tool is plunged into the lapped portions in a state in which the tool is rotated to perform friction stir spot welding. The controller controls the displacement driving unit so that at least one friction stir spot weld is formed in a region of the lapped portions which is between a plurality of resistance spot welds formed by resistance spot welding.