Abstract: Two members 10 and 20 are welded together by cutting a groove 41 having a determined cross-sectional shape using a cutting tool 60 along the abutted portion between the two members 10 and 20, inserting a filler member 30 substantially having the same cross-sectional shape to the groove so as to substantially eliminate the gap at the abutted portion, temporarily welding together the projections 12, 22 and the filler member 30, and thereafter, friction stir welding the members 10, 20 and the filler member 30 together completely using a rotary tool 81.

Abstract: The invention relates to a welding apparatus comprising a welding unit, a work-table for supporting the workpieces to be welded, and the clamping means for clamping the workpieces to the work-table in the direction towards one another during the welding operation. The welding unit comprises a friction stir welding head and a fusion welding head.

Abstract: A rivet having improved formability is provided. The rivet has a shank having a head at one end. The shank and the head have a refined grain structure. The rivet is manufactured from the region of the workpiece having a refined grain structure by first forming a region having a refined grain structure in a workpiece and then forming the rivet. The refined grain structure results in improved mechanical properties, such as formability, strength, toughness, ductility, corrosion resistance, and fatigue resistance. The improved formability of the rivet reduces the formation and propagation of cracks during the manufacture and installation of the rivets.

Abstract: A rivet having improved formability is provided. The rivet has a shank having a head at one end. The shank and the head have a refined grain structure. The rivet is manufactured from the region of the workpiece having a refined grain structure by first forming a region having a refined grain structure in a workpiece and then forming the rivet. The refined grain structure results in improved mechanical properties, such as formability, strength, toughness, ductility, corrosion resistance, and fatigue resistance. The improved formability of the rivet reduces the formation and propagation of cracks during the manufacture and installation of the rivets.

Abstract: Different metallic materials are joined in such a manner that friction heat generated by friction between a rotating probe made of a hard material and one of the metallic materials having a lower mechanical strength or a lower melting point than the other to effect plastic flow of the one material and the probe is inserted into a pit formed in a joint zone of the other material to fill the pit with the plastic flow material.

Abstract: Blades (20) are friction welded onto a disc (10) to form an integrally bladed rotor. To prevent the formation of defects in the weld interface between the blades (20) and the disc (10) a shielding gas is used. The shielding gas is introduced via two nozzles (22,24). The nozzles (22,24) are circumferentially spaced apart and located on opposite sides of the weld interface. The two gas flows oppose one another to create a curtain of gas, which flows around the weld interface. The gas curtain shields the weld interface from air and so reduces the formation of defects due to oxidation.

Abstract: A spot joining device comprises a joining tool, an induction motor for rotating the joining tool, a servo motor for vertically moving the joining tool along an axis of the joining tool, and a receiving member placed opposite to the joining tool. The joining tool includes a short-column shaped shoulder and a pin protruded downwardly along the axis from a central portion of a lower face of the shoulder at a tip end portion thereof. Two works such as aluminum alloy plates are lapped and placed on a receiving member. When the joining tool is rotated and moved downwardly, a joint spot of the works is heated and softened due to friction heat generated by the rotating pin. Thereby, plastic flow occurs in the vicinity of the joint spot. The vicinity of the joint spot is stirred and the works are fused at the joint spot. Thus, the works are spot-joined.

Abstract: The method of controlling a linear vibration welding apparatus, in accordance with the invention, may comprise the steps of: fastening a first workpiece portion in a fixed position; fastening a second workpiece portion to a reciprocating member; energizing a first single winding magnet with direct current power to create a magnetic field; sensing a location of the reciprocating member with respect to a zero point; and energizing a second magnet when the reciprocating member has crossed the zero point when moving towards the first magnet. The linear vibration welding apparatus in accordance with the invention may comprise: a frame; a flexure array; a first magnet assembly; a second magnet assembly; a digital controller; and direct current amplifiers for powering the magnet assemblies.

Abstract: A method for treating alloy before and after friction stir welding, the method comprising the following steps. First solution heat treating a multiplicity of aluminum-zinc alloy engineered components for a first time period at a first temperature. First air cooling the components in ambient air at room temperature until the components are cooled to room temperature. Friction stir welding the components to form an assembly. Second solution heat treating the assembly for a second time period at a second temperature. Additional steps and embodiments are considered.

Abstract: The invention resides in a friction stir welding tool comprising a shaft (532) and a tapered probe (504), said probe having a plurality of helically pitched surfaces (512) extending in the direction from the proximal end (530) of the probe to a distal end (531) of the probe, such that the diameter of the probe, in every longitudinal cross-section of the probe (504), diminishes continously from the proximal end (530) to the distal end (531) of the probe.

Abstract: A friction stir welding apparatus capable of stably applying a pressure force without enlarging the apparatus, and a robot having thereof are provided. A rotating tool (22) is provided with a rotational shaft (26) and a hollow surrounding shaft (27) is provided to surround the rotational shaft (26). The rotational shaft (26) is movable along an axis-of-rotation (L) and is rotated by a rotation drive motor (25) about the axis-of-rotation (L). The surrounding shaft (27) is rotatably supported by a main frame (29) and an outer threaded portion is formed around the outer peripheral thereof to be threadedly engaged with a nut member (52). The rotating tool (22) is rotatably supported by a header (40), and the header (40) and the nut member (52) are coupled together through a bracket (70).

Abstract: In a device for butt joining workpieces by friction stir welding along a connecting area, including a shaft having a driven end and, at the opposite end, a pin-like projection to be disposed in the connecting area of the workpieces, whereby, upon rotation of the shaft, the workpiece material in contact with the pin-like projection is plasticized, first and second stops with first and second shoulders are provided on the device and disposed at opposite sides of the workpieces and at least one of the stops is movable relative to the other and biased toward the other with a controllable force for engaging the workpieces between the shoulders of the stops during the friction stir welding procedure.

Abstract: A laser-assisted friction stir welding method for joining workpieces, that includes the step of providing a side face for each workpiece between first and second workpiece surfaces, each side face shaped such that, in a pressed-together condition, the side faces touch each other at the second workpiece surface and are spaced from each other in a middle region of the side faces so that a gap exists between the side faces at the first workpiece surface. The method also includes pressing together the side faces so as to form a joint area, and advancing a welding probe, while the probe is in rotary motion, along the joint area at the first workpiece surface and irradiating workpiece material located in front of the welding probe using laser radiation so as to plasticize the workpiece material along the joint area. The method also includes removing the welding probe from the joint area before the workpiece material completely solidifies.

Abstract: Grooves 18 formed to face plates 11 and 12 of a hollow shape member 10 at an abutted region with hollow shape member 20 receive projections 28 formed to face plates 21 and 22 of member 20. A connecting plate 14 orthogonal to the face plates 11 and 12 is provided to the hollow shape member 10. There is no connecting plate orthogonal to face plates 21 and 22 disposed on the end of the hollow shape member 20. Friction stir welding heat causes the face plate 21(22) to wove toward the thickness direction of hollow shape members 10 and 20, but such movement is suppressed by the groove 18 and projection 28. Thereby, the abutted region is welded flatly.

Abstract: A projection 3 is pressed into first and second members W1 and W2 with a predetermined pressure, while rotating a rotary tool 1 at a preset rotational speed, such that the first and second members W1 and W2 are sandwiched by the rotary tool 1 and stationary tool 10. The projection 3 rotates in these members to cut member textures around it, thereby generating heat. Furthermore, the cuttings formed by cutting with the projection 3 are accumulated in the members and agitated by the two tools 1 and 10, to collide against the surrounding member textures and the projection 3, thereby generating heat. Also, a first shoulder 2 is pressed in with a predetermined pressure and rotated to generate heat, thereby fusing the cuttings. While the plastic flow of the surrounding member textures is promoted, the first shoulder 2 is held at the predetermined pressure and rotational speed. The pressure per unit area is thus increased to increase the volume of plastic flow.

Abstract: An assembly, such as an aircraft component, is formed with a weld joint by, for example, using friction stir welding, FSW, to form a lap joint between a stiffer and the interior surface of the skin of the component. A sealant layer, such as a monomer sealant/adhesive is applied to the surfaces to be joined, and is cured in place by the elevated temperatures of the welding process to form an elastomeric fay surface sealing, such as a fluoroelastomeric coating, to protect the component from corrosion at the welds. Additional heat for curing may be applied by laser or induction heating or the like.

Abstract: The invention provides a friction stir welding apparatus and method and a processing apparatus and method, which are not easily affected by deformations of a work being processed. The friction stir welding apparatus inserts a rotating tool into the work and moves the rotating tool relative to the work to join members of the work. The friction stir welding apparatus and method and the processing apparatus and method of the invention, the latter cutting or grinding the work with a rotating cutter or grindstone, comprises controlling a relative distance between the tool, cutter or grindstone and the work under the joining or processing operation or an insertion depth so that the load factor or electric current of a spindle motor for rotating the tool, cutter or grindstone is within a predetermined range, and a controller therefor.

Abstract: On a main shaft 30 of a numeric control type machine tool, a rotary tool 50 is installed. The main shaft 30 is not inclined in the machine tool. A first member 70 and a second member 76 to be subjected to friction stir welding are fixed on a table 20. Relative to an axial center of the rotary tool 50, a non-linear welding portion of the first member 70 and the second member 76 is inclined by inclining the table 20. Then, by rotating the table 20 and relatively moving the portion to be welded into contact with the rotary tool 50, welding of the first member to the second member is carried out according to friction stir welding. The above-stated inclination is the inclination required for the friction stir welding. In this way, welding along a path of ring shape or circular shape (including a circular arc) using friction stir welding can be carried out easily.

Abstract: A rotary tool (200) having on the end surface of a large-diameter portion (210) facing a small-diameter portion (220) grooves (213) formed in arc-like shapes, and performing friction stir weld by inserting the end surface of the large-diameter portion (210) and the small-diameter portion to members and rotating the tool (200). By the rotation, the metal of the members moves along the grooves (213) to the center axis direction of the rotary tool (200). The arc-shaped grooves (213)are formed to curve toward the direction of rotation. Since the metal material of the members is moved toward the center, a good weld is realized even when only one of the members to be welded has a projection, or when a large gap is formed therebetween.

Abstract: A probe for friction stir welding MMCs, ferrous alloys, non-ferrous alloys, and superalloys, as well as non-ferrous alloys, the probe including a shank, a shoulder, and a pin disposed through the shoulder and into the shank, wherein the pin and the shoulder at least include a coating comprised of a superabrasive material, the pin and shoulder being designed to reduce stress risers, disposing a collar around a portion of the shoulder and the shank to thereby prevent movement of the shoulder relative to the shank, and incorporating thermal management by providing a thermal flow barrier between the shoulder and the shank, and between the collar and the tool.

Abstract: A portable inertia welder is mounted in a housing so as to afford both axial and rotational movement of a shaft with flywheel weights. Rotational motion is provided by a motor affixed to the drive shaft while axial motion is provided by means of a hydraulic housing mounted around said shaft. A chuck mounted to the shaft holds a first workpiece for rotational and axial displacement. Holding devices such as vacuum cups secure the welder to a second workpiece. A flash cutting tool and an appurtenance with a flash trap, welding flats, and an internally threaded bore are described.

Abstract: A precipitation hardened structural assembly is provided, including a first structural member and a second structural member positioned adjacent to the first structural member such that the first and second structural members define an interface therebetween. At least one friction stir weld joint joins the first structural member to the second structural member at least partially along the interface. The first and second structural members and the friction stir weld joint are solution heat treated at a first predetermined temperature schedule and precipitation heat treated at a second predetermined temperature schedule and wherein the friction stir weld joint comprises a refined grain structure having grain size of less than about 5 microns.

Abstract: A rim member 120 forming an entrance 110 and a plate 11 (21) are friction stir welded by moving a rotary tool 200 along the rim member 120. The rotary tool 120 is tilted along the direction of movement. Welding is started at right block 120R, and when the tool reaches corner portion P5 between the right block 120R and a center block 120C, the tool 200 is pulled out of the rim member 120 and plate 11 (21). Next, the tool is tilted toward the direction of movement along center block 120C. Thereafter, the tool is lowered and inserted to position, and friction stir welding is restarted. According to the invention, the direction of the rotary tool is not changed while the tool is inserted to the rim member 120. This prevents generation of excessive friction heat, and thereby realizes a good weld.

Abstract: Friction stir processing (FSP) modifies the surface microstructure of metals so that thick-section metal workpieces can be bent over large angles without formation of surface cracks. A thick 2519-T8 aluminum plate (25.4 mm thick and 50.8 mm wide) was friction stir processed across the pre-tensile surface to a depth of 6.3 mm, and was then bent at room temperature over a punch with radius 38.1 mm into a v-shaped die to an 80° bend angle. Whereas unprocessed workpieces of this type exhibited surface cracking at 31° bend angle and failed at 40° bend angle, no cracking was evident for the friction stir processed workpiece up to 80° bend angle.

Abstract: There are provided an apparatus and method for friction welding structural members. The apparatus includes a connected shank and probe. The probe defines an absorption surface and a cavity extending thereto. The absorption surface is configured to receive electromagnetic radiation from an electromagnetic radiation source such as a light source or RF generator. The radiation heats the probe, supplementing the heat generated by friction between the probe and the structural members, and thereby increasing the speed at which the probe can be used to frictionally weld the structural materials.

Abstract: Catalytic converter (2) includes a catalyst container (10) formed from a tubular blank (10′) and having a catalyst carrier, and a flange member (11) joined to the hollow member. The tubular blank (10′) is subjected to a spinning operation by forming roll or rolls (22A), to form the catalyst container (10) having a desired shape, and the opposed circumferential surfaces of the catalyst container (10) and flange member (11) are forced against each other by the forming roll or rolls (22A) or an array of presser pieces (22B) while the catalyst container and flange member are rotated relatively to each other, so that friction heat is generated for friction-welding the catalyst container and flange member at their joining portions (10b, 11b).

Abstract: A probe for friction stir welding MMCs, ferrous alloys, non-ferrous alloys, and superalloys, as well as non-ferrous alloys, the probe including a shank, a shoulder, and a pin disposed through the shoulder and into the shank, wherein the pin and the shoulder at least include a coating comprised of a superabrasive material, the pin and shoulder being designed to reduce stress risers, disposing a collar around a portion of the shoulder and the shank to thereby prevent movement of the shoulder relative to the shank, and incorporating thermal management by providing a thermal flow barrier between the shoulder and the shank, and between the collar and the tool.

Abstract: A method for friction stir welding using liquid cooling. The method includes the steps of moving a pin tool across a welding location, spraying a cooling liquid in a localized manner from a cooling ring moving with the pin tool onto a trailing region and onto lateral regions of the welding location adjacent to the pin tool, and blowing cooling gas from a gas jet moving with the pin tool from a front of the pin tool against the pin tool and against the cooling liquid emerging from the cooling ring. In addition, a friction stir welding and cooling device includes a pin tool configured to move across a welding location and a cooling ring at least partially encircling the pin tool. The cooling ring is configured to move simultaneously with the pin tool across the welding location and includes a plurality of nozzles configured to spray a cooling liquid.

Abstract: In a method and apparatus for joining at least two work pieces by friction stir welding wherein the work pieces are at least partially plasticized in the area where they are to be joined by a rotating friction tool provided with a projection which can be moved into the area of the joint to be formed, the projection on the rotating tool has a length corresponding about to the thickness of the work piece and a shoulder around the pin-like projection so that, upon movement of the tool toward the work pieces, the work piece material is plasticized by the rotating pin-like projection which moves into the work piece material until it reaches the surfaces of the lowermost

Abstract: A method of joining a pair of metal components with a rivet having a hardness that is substantially similar to at least one of the metal components. The metal components are stack upon each other and the rivet is rotated and simultaneously plunged in the metal components under pressure to friction weld and metallurgically bond the rivet to the metal components.

Abstract: A body member and flange members are butted together at a first abutment portion and a second abutment portion. The first and second abutment portions are held by first and second backing jigs, respectively. The first backing jig has a circumscribing recessed section corresponding to an inner circumferential surface of the first abutment portion. Further, the first backing jig has a circumscribing opening communicated with the bottom of the recessed section. On the other hand, the second backing jig has a circumscribing recessed section corresponding to an inner circumferential surface of the second abutment portion. Further, the second backing jig has a circumscribing opening communicated with the bottom of the recessed section. First and second buffer members are attached to the recessed sections, respectively.

Abstract: A body member and flange members are butted together at first and second abutment portions, and are retained by first and second backing jigs. In this arrangement, inner circumferential surfaces of the first and second abutment portions are fitted on and in close contact with outer circumferential surfaces of the first and second backing jigs. Subsequently, the friction stir welding is performed along each of the first abutment portion and the second abutment portion by using a probe which is rotated at a high speed.

Abstract: A weld across a joint is formed between superposed plate workpieces comprising a first plate workpiece made up of one or more plates and a second plate workpiece made up of a single plate having a joint bore formed therein by grasping the superposed plate workpieces between a rotating friction agitation welding tool and a back-up tool, rotating and advancing the friction agitation welding tool toward the back-up tool in an axis of welding to force the friction agitation welding tool to penetrate into the first plate workpiece while urging the friction agitation welding tool and the first plate workpiece together whereby generating frictional heat to plasticize workpiece material around the friction agitation welding tool and cramming a plasticized workpiece material into the joint bore of the second plate workpiece and allowing the plasticized workpiece material to solidify.

Abstract: The method comprises introducing a tip of a solid phase welding tool between adjacent surfaces of a crack formed in an aircraft skin. The tool is then operated to produce a friction stir weld so as to weld the adjacent surfaces together and thereby repair the crack. Apparatus for performing the method comprises a base having carriage thereon, the arm being pivotally mounted on the carriage and supporting the friction stir welding tool. The position of an arm can be adjusted by a screw which drives the rotating tip of friction stir welding tool into the crack to be repaired. The carriage is then moved along the base to draw the tip along the crack. The apparatus is portable and is particularly useful for repairing a cracked skin on an aircraft.

Abstract: A probe for friction stir welding MMCs, ferrous alloys, non-ferrous alloys, and superalloys, as well as non-ferrous alloys, the probe including a shank, a shoulder, and a pin disposed through the shoulder and into the shank, wherein the pin and the shoulder at least include a coating comprised of a superabrasive material, the pin and shoulder being designed to reduce stress risers, disposing a collar around a portion of the shoulder and the shank to thereby prevent movement of the shoulder relative to the shank, and incorporating thermal management by providing a thermal flow barrier between the shoulder and the shank, and between the collar and the tool.

Abstract: A system and associated friction stir welding (FSW) assembly, controller and method for performing a friction stir welding operation are provided. The friction stir welding system includes a FSW device, such as a CNC machine, that includes an actuator capable of moving a FSW tool relative to a workpiece. The system also includes a controller capable of controlling the FSW device to drive the actuator to move the FSW tool. In this regard, the actuator is capable of being driven such that the FSW tool is capable of performing a friction stir welding operation on the workpiece. The controller is capable of monitoring a torque of the actuator to thereby control the FSW device to drive the actuator such that the torque is maintained within a range about a torque setting.

Abstract: A friction stir welding device that is configured to perform convention friction stir welding as well as self-reacting friction stir welding. A pin passes through an upper shoulder and can selectively attach to and detach from a lower shoulder in a preferred embodiment. A controller maintains the discrete position of, and/or force applied by, the upper and lower shoulders during self-reacting friction stir welding, or maintains the pin at a desired depth and/or applied force during conventional friction stir welding.

Abstract: A friction stir rivet is rotated in a precessing motion and driven through a first fusible workpiece into an engaged second fusible workpiece, causing local portions of the first and second workpieces to plasticize. When the rivet is driven through the first workpiece and into the second workpiece, rotation is stopped and the plasticized material solidifies around the rivet creating an enlarged weld joining the metal workpiece and encompassing the rivet, which provides additional mechanical strength.

Abstract: There is provided a method capable of decreasing a friction force in friction stir welding, in which a welding tool is used. In a method of friction stir welding workpieces together by rotating and pressingly plugging a welding tool, formed from a harder material than the workpieces, into a weld zone of the workpieces and moving the welding tool relatively in a welding direction, a power supply device allows a current to flow between the welding tool 1 and the workpieces to cause resistance heating of the welding tool. Combined use of resistance heating makes it possible to decrease a friction force. Preferably, a conductive ceramic is coated on surfaces of the welding tool to cause resistance heating.

Abstract: A damper for reducing vibration in a least a portion of a component during inertia welding. The damper includes a generally annular body having a spiral slot formed therein.

Abstract: A friction stir welding machine includes a table for supporting parts to be welded and a frame extending over the table. A first drive is supported by a first element of the frame and is operatively connected to a spindle having a tool. The first drive moves the tool in a first direction, and the first drive disengages from the spindle after the tool contacts the material. A second drive is supported by a second element of the frame and is operatively connected to the spindle for moving the tool into the parts at a joint, thereby initiating friction stir welding process. The friction stir welding machine has a pair of rollers mounted in a roller support with an axis of rotation substantially perpendicular to an axis of rotation of the tool. The rollers contact a surface of the material in response to the tool penetrating the material to a desired depth.

Abstract: The method of manufacturing a structural assembly includes positioning a first structural member at least partially adjacent a second structural member to define an interface therebetween and inserting a rotating plug into the first and second structural members at the interface to thereby join the first structural member to the second structural member. The resulting friction plug weld provides a relatively strong joint between the structural members, requires less forming and machining time, and is compatible with single-sided tooling. Additionally, the friction plug weld is compatible with other joining methods, such as friction stir welding.

Abstract: Disclosed is a friction stir welding method for welding two members to be welded which differ in physical properties and/or mechanical properties by abutting the two members to each other, inserting a pin portion of a rotary tool having the pin portion and a shoulder portion to the abutment surfaces of the two members, and moving the rotary tool along the abutment surfaces. The pin portion is inserted to only one of the members, the pin portion is not inserted to the other of the members but only the shoulder portion is set in contact with the other of the members, and, while this condition is maintained, the rotary tool is moved. With this method, only the member on the side where the pin is inserted can be made to undergo plastic flow attendant on a friction stir action. The metal in plastic flow is pressed against the opposite member at an elevated temperature and high pressure, whereby diffusion of atoms is caused in the vicinity of the abutment surfaces, and the members are welded.

Abstract: The present invention relates to rotary friction welding and non-rotary motion friction welding, providing means for controlling ductilities of the components during the welding process so as to bias the welding process in favor of a first component or to match the ductilities of different components thereby facilitating the welding process.

Abstract: A friction stir welding spindle includes a support having a center bore. A spindle shaft is adapted to support a stir welding tool and extends within the bore. A bearing assembly allows simultaneous rotational and axial displacement of spindle shaft in the bore relative to the support. A sensing device is adapted to provide an output signal indicative of at least one of a force coincident with axial displacement of the spindle shaft and an axial position of the spindle shaft.

Abstract: A friction stir welding anvil and method of producing a friction stir welding anvil that precludes diffusion or mechanical bonding of the anvil to the work pieces are provided. The alternatives for producing such an anvil comprise coating the anvil with diffusion barriers such as oxides, nitrides, intermetallics, and/or refractory metals; manufacturing an anvil either completely or partially from the same; or placing a coating of such materials in the form of a thin sheet or a powder between the anvil and the work pieces. The anvil disclosed herein exhibits high strength and hardness even at elevated temperatures, such as those greater than 800° C., so as to prevent the anvil from mechanically or diffusion bonding to the work pieces and so as to minimize, or eliminate altogether, anvil deformation.

Abstract: Method of joining together two planar members, by a friction stir welding operation wherein a rotary tool having a probe is moved relative to a joint region defined between the mutually butted planar members such that the probe is rotated and inserted in the joint region. The welding operation is performed by using a tab plate having a cutout formed in its end face such that the cutout has a width not smaller than a radius of a peripheral circle to be described by the shoulder surface, and a depth not smaller than a minimum radius of the probe and not larger than the radius of the peripheral circle.

Abstract: A first metal member is contacted with a second metal member. A metal fastener is provided including a core and a cladding disposed upon the core. The fastener is driven through the first member and into the second member, inducing friction between the fastener, the first member and the second member for at least locally melting portions of the cladding, the first member and the second member to form a flowable material that solidifies and metallurgically bonds the fastener to the first member and the second member for attaching the members together.

Abstract: The invention provides a friction stir welding apparatus and method and a processing apparatus and method, which are not easily affected by deformations of a work being processed. The friction stir welding apparatus inserts a rotating tool into the work and moves the rotating tool relative to the work to join members of the work. The friction stir welding apparatus and method and the processing apparatus and method of the invention, the latter cutting or grinding the work with a rotating cutter or grindstone, comprises controlling a relative distance between the tool, cutter or grindstone and the work under the joining or processing operation or an insertion depth so that the load factor or electric current of a spindle motor for rotating the tool, cutter or grindstone is within a predetermined range, and a controller therefor.

Abstract: The invention provides a discontinuous friction stir welding apparatus and welding method having a compact machine head capable of corresponding to a wide usage. In a friction stir welding apparatus provided with a tool (1) having a shoulder portion (1a) with a large diameter and a pin portion (1b) with a small diameter protruding in an axial direction, and welding by inserting the tool to a material to be welded while rotating the tool, the tool, a moving mechanism of the tool and a backing member (5) for the welded material are received in one frame (10). The tool moving mechanism has a main axis motor (2) for rotating the tool, an axial moving apparatus (4, 13a, 13b, 14) for moving the tool in a direction of a rotation axis, and a welding direction moving apparatus (9, 17) for moving the tool along a weld line of the welded material.