The presently disclosed technology includes a friction stir welding apparatus comprising a frame, a moving platform and a parallel mechanism composed of three branch mechanisms, wherein a first branch mechanism comprises a first sliding pair, a first revolute pair, a telescopic rod and a first spherical pair connected in sequence. A second branch mechanism and a third branch mechanism both comprise a third sliding pair, a second revolute pair, a third linkage and a second spherical pair connected in sequence. The friction stir welding apparatus has high stiffness, low inertia, high dynamic performance and high accuracy, which can achieve precision welding with high requirements on processing quality and accuracy for jointing annular seams of large-scale rocket fuel storage tank barrels in the aviation field, for example. The presently disclosed technology also includes a corresponding friction stir welding system.

A friction stir welding method is provided that can prevent defective welding due to a shortage of metal. The friction stir welding method welds metal members (1, 2) using a primary joining rotary tool (F) having a stirring pin (F2), and includes steps of: butting in which the metal members (1, 2) are butted with each other at an angle to form a butted portion (J1); buildup welding in which buildup welding is applied along an inner corner of the metal members (1, 2) formed in the butting step to cover the inner corner by a weld metal (M); and inner corner joining in which only the stirring pin (F2) in rotation is inserted in the inner corner to plastically fluidize the weld metal (M) and the metal members (1, 2) for friction stir welding of the butted portion (J1).

A low-temperature joining method effectively suppresses reductions in the mechanical properties of a junction of various types of high-tensile steel or aluminum, and of a heat-affected zone; and produces a joint structure. A method for joining two metal materials by forming a joint interface in which the two metal materials face each other at a joint portion and plunge a rotation tool caused to rotate at a prescribed speed into the joint, the method for low-temperature joining of metal materials characterized in that the peripheral velocity of the outermost periphery of the rotation tool is set to 51 mm/s or less, whereby the recrystallization temperature inherent to the metal materials is reduced by introducing a large strain to the joint, and recrystallized grains are generated at the joint interface by setting the joining temperature to less than the recrystallization temperature inherent to the metal materials.

A friction stir welding tool comprises a cylindrical shank, a shoulder portion disposed at a distal end of the shank, a pin extending from the shoulder, a cutting insert mounted within a concave portion at the distal end of the shank, and a scribe cutter mounted at a distal end of the cutting insert. The cutting insert extends distally through a channel in the pine, and the scribe cutter extends from a distal end surface of the pin in an offset position. The distal end surface of the pin is perpendicular to a longitudinal axis of the shank.

A double-pin friction stir device may include an annular friction surface with a central hole, where the annular friction surface is rotatable about a normal axis of the annular friction surface in a first direction. The device may further include a first pin extending through the central hole along a normal axis of the annular friction surface. A distal end of the first pin may protrude from the annular friction surface and the first pin may rotate about a longitudinal axis of the first pin in the first direction. The device may further include a second pin extending through the central hole along and parallel with the first pin, where a distal end of the second pin protrudes from the annular friction surface. The second pin rotates about a longitudinal axis of the second pin in a second direction opposite the first direction.

A rotary tool includes: a main body having a fixed unit and a rotary shaft; a stirring pin rotatable and movable relative to an axial direction of the rotary shaft, and inserted into a joint member to perform friction stirring; and a shoulder that is arranged on the main body so as not to receive a rotary force from the main body but to be movable relative to the axial direction of the rotary shaft, and that presses the joint member while in contact with the joint member, wherein the stirring pin and the shoulder are mounted to form an assembly so as to be relatively movable and to move integrally in the axial direction of the rotary shaft, and the rotary tool further includes a first elastic member that biases the assembly toward a distal-end side of the stirring pin relative to the axial direction of the rotary shaft.

The invention relates to a method and to a device for welding together two joining partners by means of friction stir welding, which prevents the joining partners being contamined by welding residue. The method comprises the following features: a welding head that can be integrated into any machine, said welding head being in the form of a spindle drive driven by a drive unit, comprising a mounting flange for securing the device assisting the welding process, and a clamping system for receiving a frustoconical-shaped tool having a welding and smoothing shoe for guiding a welding pin (11), a device (17) integrated into the welding and smoothing shoe for grinding the waste produced during the welding process, the waste produced during welding is then removed by means of one inlet channels for fluid arranged in the upper and/or lower area of the frustoconical-shaped tool for the fluid (20, 18) and a suction channel (19).

The invention relates to a device and a method for changing the welding direction of the welding shoulder of a system for a friction stir welding process virtually without delay when required by the geometric arrangement of the joint partners to be welded or by a material unevenness, having the following method features: a) a main part (1) with a horizontally movable bridge support (5) has a friction welding head (12) which can be vertically adjusted together therewith and which has a pin receiving area (13) for mounting and driving a welding pin tip (14), wherein the welding shoulder (18) has a welding shoulder receiving area (17) which is supported at multiple points, and b) the welding shoulder receiving area (17) can be adjusted to any angle of attack relative to the joint partners by means of different push-pull rods (16) during the welding process.

An object is to provide a friction stir welding method and apparatus that provide sufficient strength and good welding workability by advantageously eliminating plastic flow deficiency generated as a result of insufficient heating of workpieces.

In friction stir welding for steel sheets (3,3) as workpieces, a pair of facing rotary tools (1,15) are inserted into a non-welded part from both one surface side and the other surface side of the steel sheets (3,3), the rotary tools move in a welding direction while rotating, and in addition, a preheating process for heating steel sheets (3,3) is performed by heating means (5) provided in front of the rotary tools (1,15). The configuration of the pair of facing rotary tools (1,15) and the surface temperature, area, position, and so forth of a heated region in the preheating process are strictly controlled.

A friction stir spot welding method performs friction stir spot welding of a pair of workpieces having a coating film formed on at least one welding surface by using a refill friction stir spot welding device including rotary tools. The method includes removing the coating film by plunging a distal end of the shoulder member into one workpiece up to a position closer to the surface than the welding surface, while rotating the shoulder member as a rotary tool around the axis, and rotating the shoulder member in a state in which the surface of one of the pair of workpieces, with the welding surfaces being overlaid on each other, is pressed by the end face of the clamp member and performing friction stir spot welding of the pair of workpieces after the coating film removal by using the pin member and the shoulder member as rotary tools.