A friction stir spot welding device includes a pin member, a shoulder member, a rotation driving unit, a tool driving unit, a position detector, and a controller, wherein the controller sets as reference position of the tip end surface of the pin member or shoulder member at a time point when the pin member tip end surface or shoulder member contacts an obverse surface of an object and controls the tool driving unit reducing a pressing force to the object by the pin member and pressing force to the object by the shoulder member in a next welding process, and/or controls the rotation driving unit reducing the pin member rotational speed and shoulder member rotational speed in the next welding process, in case where a first position is the position of the tip end surface of the pin member or the shoulder member is within a first region.

A bobbin tool is disclosed that includes a top shoulder, a bottom shoulder, and an axial pin that extends between the top and bottom shoulders. The bottom shoulder has an annular shoulder end surface, a back surface opposite the annular shoulder end surface, and a side surface that joins the annular shoulder end surface and the back surface. One or more and radially-extending blades may be disposed on the side surface of the bottom shoulder and/or one or more axially-extending blades may be disposed on the back surface. The one or more blades provide the bobbin tool with an ability to friction stir weld a variable thickness workpiece assembly, axially plunged through the workpiece assembly along an axis of rotation of the bobbin tool, and/or be extracted through the workpiece assembly along an axis of rotation of the bobbin tool.

A welding tool for joining at least two workpieces at a joining region by friction stir welding includes a tool pin arranged along one axis of the welding tool, for applying frictional heat to the workpieces. The welding tool also includes a shoulder surrounding the tool pin, for separating the joining region from the surrounding area. The shoulder is moveable essentially parallel to the axis of the welding tool.

The present disclosure arranges a pair of friction stir welding tools including probes and fixed shoulders at corner portions between a first workpiece and a second workpiece. The friction stir welding tools are arranged so that regions where the probes are embedded in the respective the corner portions and stirred are positioned symmetrically with respect to the second workpiece. With this arrangement of the friction stir welding tools, the corner portions are friction stir welded simultaneously.

In the present disclosure, friction stir welding tools having probes and stationary shoulders are disposed at corners between a first workpiece and a second workpiece. A welding device main body includes axially perpendicular movement units for moving spindle units, which hold the respective friction stir welding tools on a frame, in directions perpendicular to rotary shafts of probes, and axial movement units for moving the spindle units in directions parallel to the rotary shafts of the probes.

A metal composite and a metal joining method that are capable of suppressing an influence on joining strength of a friction stir welded section due to a tool hole formed when a tool is extracted, in the case in which two metals are joined through friction stir welding. In an overlapping section in an axial direction in which a first shaft and a second shaft overlap in the axial direction, an inscribed section in which the first shaft and the second shaft come in contact with each other and an non-inscribed section in which the first shaft and the second shaft do not come in contact with each other are formed. In the non-inscribed section, a plate thickness of the second shaft is decreased. Then, a starting point of a friction stir welded section is formed in the inscribed section, and an endpoint is formed in the non-inscribed section.

A quick connect refill friction stir spot welding tool includes a clamp having a first radially-projecting mounting tab configured for engaging a first mounting slot in a refill friction stir spot welding weld head. A friction sleeve is located coaxially within the clamp and has a second radially-projecting mounting tab configured for engaging a second mounting slot in the refill friction stir spot welding weld head. The second radially-projecting mounting tab is located higher along an axis of the tool than the first radially-projecting mounting tab, and radially inward thereof. A friction pin is located coaxially within the clamp and friction sleeve. The clamp and friction sleeve are attachable to and detachable from the refill friction stir spot welding weld head by rotations through less than 360 degrees.

A bridge member is installed in an opening of a water jacket, and a probe of a friction stir welding tool, which rotates about an axis parallel to a cylinder axis, is pressed against a central part of an upper surface of the bridge member. The probe is kept pressed against the central part of the upper surface for a predetermined time to cause side surfaces of the bridge member to expand and come into contact with both a cylinder wall and an outer wall. The probe is moved from the central part of the upper surface to the outer wall, or the cylinder wall, while the probe is kept pressed against the upper surface, thereby friction-stir welding the outer wall, or the cylinder wall, with the bridge member to each other, and after that, the probe is removed off the top deck.

A method of inserting a rivet into a workpiece comprises moving the rivet and workpiece relative to one another, along a longitudinal axis of the rivet, so as to drive the rivet into the workpiece. The rivet is rotated about its longitudinal axis, relative to the workpiece, for at least part of the time during which it is in contact with the workpiece. The speed of said rotation, or the speed of movement along the longitudinal axis of the rivet, is altered at least once before driving of the rivet into the workpiece is complete. One axial end of the rivet has a tip for piercing the workpiece, and the rivet has a substantially cylindrical shank extending longitudinally from the tip. The shank has one or more surface irregularities.

An edge of each of a first metal member and a second metal member is formed to have a U-shaped cross section with a first horizontal plate projecting from a base edge of a vertical plate, and with a second horizontal plate projecting from a top edge of the vertical plate. The second metal member includes a projecting part. The joining method includes: an abutting step of forming an abutted part by abutting a front surface of the first horizontal plate the first metal member against a second side surface of the second metal member; and a joining step of performing friction stir welding of the first metal member and the second metal member by inserting a stirring pin from the projecting part and moving a joining rotating tool along an inner corner at the top edge of the vertical plate of the second metal member while making only the stirring pin in contact with the first metal member and the second metal member.