JP2007029979A - Double acting type rotary tool for friction stir spot welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double acting type rotary tool for friction stir spot welding, which is configured such that a probe and a shoulder member are separate members and can separately move in the axial direction, and the material to intrude into a gap between the probe and the shoulder member can be discharged outside so as not to adhere to the gap. <P>SOLUTION: The probe 12 has a stepped structure integrally composed of a probe tip end portion 12a having a slender small diameter round rod shape and a probe base portion 12b having a round rod shape having a diameter larger than that of the probe tip end portion 12a. An adhesion preventing means is configured by the stepped portion (an end face 16) of the probe tip end portion 12a and the probe base portion 12b. The double acting type rotary tool 10 for friction stir spot welding is configured by inserting the probe 12 into the central bore of a cylindrical shoulder member 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a double-acting rotary tool for friction stir spot joining, and in particular, a probe and a shoulder member are configured separately, and can be rotated around an axis and separately moved in an axial direction. Further, the present invention relates to improvement of a rotary tool for friction stir spot welding having a double-acting structure.

  Conventionally, in the automobile manufacturing process, the body member and various parts are integrated by overlapping a plurality of metal plate members and connecting them by point joining such as rivets and resistance spot welding. In addition, the connection method of the metal plate material by such point joining is used in various vehicles such as railway vehicles, transportation equipment such as aircraft, and structures such as home appliances and building materials. In such fields as well, it has been widely adopted.

  On the other hand, in Patent Document 1 and the like, a friction stir welding method is proposed in which metal members are joined using frictional heat as a joining method with less heat input during joining and less degree of softening or distortion. In addition, by adopting such a friction stir welding technique, a technique for spot joining the overlapping portions of a plurality of metal plate members has been studied, thereby, rather than conventional resistance spot welding or joining by rivets, Various friction stir spot welding methods (Friction Stir Spot Welding) have been proposed (see Patent Documents 2 to 4 and the like), because joint quality is good and a good joining state can be stably obtained.

  However, all of these proposed various friction stir spot joining methods are basically pin-type tools having a structure in which a pin-shaped hard probe is integrally provided at the tip of a rod-shaped tool body ( Rotating tool), rotating it at high speed, inserting it into the overlapping part of the predetermined metal plate member, and pressing the shoulder part composed of the tip of the tool body of such pin type tool against the overlapping part By inserting frictional heat between the shoulder and probe and the superposition site, the material is plastically flowed, and a stirring region is formed around the probe, thereby inserting the probe. In such a point joining operation, the pin type tool is attached after the point joining is completed. When the metal plate member is pulled out from the stirring region (stirring portion) formed in the overlapping portion, a recess (hole) having a shape corresponding to the insertion portion including the probe at the tip of the pin type tool remains there. There are inherent problems such as causing a problem of liquid pool during coating, and adversely affecting the joint strength (bonding strength) of the metal plate members to be joined.

  For this reason, the applicant of the present application first uses a rotary tool having a double-acting structure in which the probe and the shoulder member are separately configured in Patent Document 5 and separately movable in the axial direction. A friction stir zone is formed in the overlapped portion of the overlapped portion of the metal plate member to be formed by inserting and projecting the rotated probe and the shoulder member, respectively. After joining the metal plate members, the shoulder member is advanced while the probe is pulled out of the friction stir zone, and the surface of the friction stir zone is pressed, so that the material of the surrounding friction stir zone flows into the probe hole. Then, when the probe hole is filled, and the probe and the shoulder surface of the shoulder member are flush with each other, a method in which the rotary tool is detached from the overlapping portion, It was to Raka.

  However, according to the friction stir spot joining method using such a double-acting rotary tool, even if the plate thickness of the metal plate members to be joined changes variously, it is possible to cope with one rotary tool. In addition to the features that can be achieved, it is possible to effectively avoid the fact that probe pull-out holes remain in the joint provided in the friction stir zone. Although the problem that the accumulation problem etc. can be advantageously solved is exhibited, since the rotary tool to be used has a double-acting structure, there is inevitably a clearance (gap) between the probe and the shoulder member. Therefore, there is a problem that the material of the bonded metal plate member constituting the friction stir zone (joining portion) enters and adheres to such clearance, and thereby the probe Between the shoulder member, or a mutually independent operation (movement) difficult, thus, a problem that it is impossible to perform repeated friction stir spot joining operation, are inherent.

Japanese Patent No. 2712838 JP 2001-321967 A JP 2001-314983 A JP 2002-120077 A JP 2001-259863 A

  Here, the present invention has been made in the background of such circumstances, the problem to be solved is that the probe and the shoulder member are configured separately and can be moved separately in the axial direction. In a friction stir spot joining rotary tool for a friction stir spot joining with a double-acting structure in which the material that enters the gap between the probe and the shoulder member is discharged to the outside so that it does not adhere to the gap. It is to provide a double-acting rotary tool.

  In the present invention, in order to solve such a problem, a rod-shaped probe that is inserted while being overlapped with a plurality of metal members to be joined and rotated from one side of the overlapping portion, and the probe A cylindrical shoulder member having a shoulder surface that is fitted around and coaxially positioned on the one side and is brought into contact with the surface of the one side under rotation, and the probe and the shoulder member are separated from each other. In the rotary tool for friction stir spot welding of a double-acting structure constructed in a body and separately movable in the axial direction, the material of the metal member to be joined that has entered between the probe and the shoulder member is used. The gist of the present invention is a double-acting rotary tool for friction stir spot joining, characterized in that an adhesion preventing / dissolving means for discharging to the outside is provided.

  In addition, according to one of the desirable modes of the double-acting rotary tool for friction stir spot joining according to the present invention, the adhesion preventing / dissolving means is formed on the outer peripheral surface of the probe rather than the tip surface. The side is composed of a stepped portion having a large diameter, and after the friction stir spot joining operation, the probe protrudes relative to the shoulder member, whereby the intrusion material is discharged to the outside. On the other hand, according to another desirable mode, the adhesion preventing / dissolving means is constituted by a screw portion formed on the outer peripheral surface of the probe, After the operation, the intrusion material is discharged to the outside by rotating the probe or protruding relative to the shoulder member.

  According to another preferred embodiment of the double-acting rotary tool for friction stir spot joining according to the present invention, the adhesion preventing / eliminating means is in sliding contact with the outer peripheral surface of the probe and adheres to it. The brush means is capable of removing the intruding material, and after the friction stir spot joining operation, the probe protrudes relative to the shoulder member, and against the outer peripheral surface of the protruding probe. Thus, the brush means can be relatively brought into sliding contact.

  Furthermore, according to another preferable aspect of the double-acting rotary tool for friction stir spot joining according to the present invention, the adhesion preventing / eliminating means is provided so as to penetrate the cylindrical wall portion of the shoulder member. The intrusion material is discharged to the outside through the discharge hole, and according to still another preferred embodiment, the adhesion preventing / resolving means comprises: Gas blowing means for blowing gas into the gap between the probe and the shoulder member from the base side toward the tip side, and after the friction stir spot joining operation, the gas by the gas blowing means The intrusion material is discharged to the outside by blowing.

  As described above, according to the double-acting rotary tool for friction stir spot joining according to the present invention, the probe and the shoulder member are configured as separate bodies, and have a double-acting structure that can be separately moved in the axial direction. Even if there is a gap between them, that is, between the outer peripheral surface of the probe and the inner peripheral surface of the shoulder member, the adhesion preventing / resolving means prevents the metal member to be joined that has entered such a gap. Since the material is discharged to the outside, the trouble that is caused by the adhesion of the material that has entered the gap and fixing the probe to the shoulder member can be effectively suppressed or prevented. It becomes.

  In addition, according to one of the desirable embodiments according to the present invention, on the outer peripheral surface of the probe of the double-acting rotary tool for friction stir point junction, by forming a stepped portion having a larger diameter than the tip side on the base side, When the probe protrudes from the shoulder member, the material of the metal member to be joined that has entered the gap between the outer peripheral surface of the probe tip side and the outer peripheral surface of the shoulder member is removed from the end surface of the stepped portion formed on the probe. The metal material that has been pressed and penetrated into such a gap can be effectively discharged out of the gap. On the other hand, according to another desirable mode according to the present invention, by forming a threaded portion on the outer peripheral surface of the probe, the material that has entered the gap by the threaded portion of the threaded portion is extruded to the outside in the same manner as the stepped portion described above. Or by rotating the probe, the screw feed action causes the gap between the probe and the shoulder member, in other words, the metal material that has entered between the valley of the screw portion and the inner peripheral surface of the shoulder member. , Can be effectively discharged to the outside.

  Further, according to another preferred embodiment, by providing a brush member so as to be in sliding contact with the outer peripheral surface of the probe, the probe protrudes from the shoulder member, and the outer peripheral surface of the protruded probe is rubbed with such a brush member. Thus, by the friction stir spot joining operation, it is possible to effectively remove the metal material that penetrates between the outer peripheral surface of the probe and the inner peripheral surface of the shoulder member and adheres to the outer peripheral surface of the probe member. It is.

  Furthermore, according to one of the other desirable modes of the double-acting rotary tool for friction stir point according to the present invention, such discharge is provided by providing a discharge hole in the shoulder member so as to penetrate the cylindrical wall portion. Through the hole, the material that has entered the gap between the probe and the shoulder member during friction stir welding is discharged to the outside. Further, according to one of the other desirable embodiments, a gas blowing means is used from the base side to the tip side of the rotary tool with respect to the gap formed on the outer peripheral surface of the probe and the inner peripheral surface of the shoulder member. By blowing in gas, the material that has entered into such a gap can be effectively discharged to the outside by the pressure of the gas, and metal materials can also enter into the gap during the friction stir spot welding operation. It becomes possible to prevent.

  In short, according to the double-acting rotary tool for friction stir point joining according to the present invention, the stirring flow during the friction stir spot joining operation is performed in the gap formed between the inner peripheral surface of the probe and the outer peripheral surface of the shoulder member. Even if a metal material to be squeezed in, such an intrusion material can be effectively discharged to the outside by means of anti-adhesion means, thereby avoiding troubles due to material adhesion in the gap. However, the friction stir spot joining operation can be performed continuously and repeatedly.

  Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

  First, FIG. 1 schematically shows an example of a friction stir spot welding rotary tool according to the present invention with its tip portion enlarged. In FIG. 1, a rotary tool 10 for friction stir spot welding is positioned above the overlapping portion of the metal plates 2a and 2b, which are metal members to be joined, while the back side (lower side) of the lower metal plate 2b. ) Is provided with a backing jig (not shown). And the rotary tool 10 is comprised in the structure where the shoulder member 14 is extrapolated outside the probe 12 by which the front-end | tip part was made into the step shape, and they are arrange | positioned coaxially.

  More specifically, the probe 12 is arranged such that its axial direction is positioned in the vertical direction in FIG. 1, and has a narrow and small-diameter probe tip 12a having a round bar shape and a diameter larger than that of the probe tip 12a. It has a stepped structure formed integrally with a base side (upper side in the figure) of a round rod-like probe base 12b. The stepped portion between the probe base 12b and the probe tip 12a is an end surface 16. ing. And the adhesion prevention means according to this invention is comprised by such a stepped structure. As in the prior art, the probe 12 can be rotated around its axis at a high speed by a rotation driving device (not shown) connected to the probe base 12b side, and is reciprocated in the axial direction ( (Extrusion operation and retraction operation) are possible.

  Further, the shoulder member 14 that is externally inserted into the probe 12 has a cylindrical shape, and the diameter of the center hole thereof is slightly larger than the outer diameter of the probe base 12b portion of the probe 12. The probe 12 is easily rotated and movable in the axial direction within the center hole. Even in the shoulder member 14, similarly to the probe 12, it can be rotated at a high speed around the axis in conjunction with the probe 12 or separately from the probe 12 by a rotation driving mechanism (not shown). In addition, reciprocating movement (extrusion operation + retraction operation) in the axial direction is possible.

  It should be noted that the portion of the shoulder member 14 that contacts at least the metal plates 2a and 2b (bonded metal members) and the portion of the probe tip 12a of the probe 12 that contacts at least the metal plates 2a and 2b are the metal plates 2a, 2b, It is formed of a material harder than the material 2b, and can be prevented from being worn out in the friction stir spot joining operation. For example, the metal plates 2a and 2b (metal members to be joined) are made of aluminum. In the case of a material, it is formed of a steel material.

  By the way, using the rotary tool 10 according to the present invention as described above, when the metal plates 2a and 2b that are the metal members to be joined are friction stir spot joined, for example, according to the process shown in FIG. It is. In this case, the metal plates 2a and 2b are arranged to overlap each other on a predetermined backing jig (not shown), and are clamped in a fixed position by a predetermined clamping member. The two metal plates 2a and 2b are all made of a metal material that can be friction stir welded, for example, aluminum, aluminum alloy, copper, copper alloy, iron, or an alloy thereof. Further, for the metal plates 2a and 2b, the same material or different materials are appropriately selected and used.

  Then, first, as shown in FIG. 2A, the probe 12 of the rotary tool 10 and the shoulder member 14 are pressed against the surface of the upper metal plate 2a while rotating at high speed, and the tip of the probe 12 is The frictional heat is generated between the surface and the shoulder surface of the shoulder member 14 and the surface of the metal plate 2a to form a frictional heat generating portion, and then the probe 12 is inserted until reaching the lower metal plate 2b, and the metal plates 2a, 2b The friction stir zone 20 is formed over the distance, and the friction stir spot joining of the metal plates 2a and 2b is performed (see FIG. 2B). When the rotary tool 10 is brought into contact with the surface of the metal plate 2a, the tip surface of the probe 12 and the shoulder surface of the shoulder member 14 are pressed against the surface of the metal plate 2a, and then the probe 12 is protruded from the shoulder member 14 and inserted into the metal plates 2a and 2b, or the probe 12 is protruded from the shoulder member 14 and the tip surface of the probe 12 is brought into contact with the metal plate 2a. Then, after forming the frictional heat generating portion, the probe 12 may be inserted until reaching the metal plate 2b to form the friction stirring region 20. In addition, the probe 12 and the shoulder member 14 constituting the rotary tool 10 can be rotated independently of each other, and can be rotated independently, and the insertion depth of the probe 12 is as follows. Depending on the plate thickness of the metal plates 2a and 2b, it is determined appropriately.

  When the friction stir operation by the rotary tool 10 is completed in this manner, the probe 12 is pulled out (raised) and pushed by the shoulder member 14 as shown in FIG. Will be embedded by the flow of the metal material from the other part of the friction stir zone 20, and then the friction stir zone with the shoulder surface of the shoulder member 14 and the tip surface of the probe 12 being flush with each other. After pressing 20, the rotary tool 10 is detached from the surface of the metal plate 2 a, so that a substantially flat joint 22 is formed, and the desired friction stir spot joining of the metal plates 2 a and 2 b is realized. It is.

  However, when performing such a friction stir spot joining operation, friction stir between the probe 12 and the shoulder member 14, more specifically, between the outer peripheral surface of the tip of the probe 12 and the inner peripheral surface of the shoulder member 14. In some cases, the metal material that is caused to flow in the friction stir zone 20 may intrude and adhere to the inner and outer peripheral surfaces, thereby making it difficult to perform the friction stir spot joining operation. As a means, since the stepped structure is adopted for the probe 12, the metal material that has entered the gap can be discharged, for example, by the following process.

  That is, as shown in FIG. 3A, after the friction stir welding operation is completed, the probe 12 is located at a position where the rotary tool 10 does not interfere with the metal plates 2a and 2b (metal members to be joined). The shoulder member 14 is relatively protruded. Then, as shown in FIG. 3 (b), the end surface 16 of the stepped portion formed between the probe tip portion 12a and the probe base portion 12b of the probe 12 enters and adheres to the gap. When the metal material (24) is subjected to the extrusion pressure, and under such a condition, the protruding operation of the probe 12 is further advanced, so that the adhered metal material (24) is pushed downward to the outside. It will be discharged.

  Then, as shown in FIG. 3C, when the entire probe tip 12a is protruded from the shoulder member 14, the metal material (24) that has entered and adhered to the gap is brought into contact with the probe 12 and the shoulder. Then, the probe 12 is discharged to the outside through the gap between the member 14 and the protruding probe 12 is then pulled back to the original position, and the rotary tool 10 is moved to a position where the next joining operation is performed. By moving it, the friction stir spot joining operation can be performed continuously [see FIG. 3 (d)]. The protruding operation of the probe 12 from the shoulder member 14 is performed while rotating the probe 12 and the shoulder member 14 respectively, or only one of them is rotated, and further, neither is rotated. It is also possible to do it.

  As described above, according to the rotary tool for friction stir spot joining according to the present invention, the end surface 16 of the stepped portion in the stepped structure as the adhesion preventing means formed on the outer peripheral surface of the probe 12 is used for the double-acting rotary tool. The metal material (24) that has entered and adhered to the gap necessarily existing between the probe 12 and the shoulder member 14 is simply ejected from the gap to the outside. Since it is possible to extrude and discharge, troubles such as rotation failure of the probe 12 and the shoulder member 14 due to adhesion of the metal material (24) to the gap can be advantageously avoided, The friction stir spot joining operation can be performed continuously and repeatedly.

  Here, in the stepped structure of the probe 12 employed as the adhesion preventing / eliminating means, if the height of the stepped portion (the difference in outer diameter between the tip portion 12a and the base portion 12b) is too high (large). From the point that the amount of intrusion of the metal material (24) is increased and the height is too low (small), it is difficult to sufficiently exert the discharging action of the adhered metal material (24). Generally, it is desirable that the height be about 0.01 to 0.5 mm, preferably about 0.03 to 0.2 mm.

  As mentioned above, although one typical embodiment of the adhesion preventing / dissolving means according to the present invention has been described in detail, it is merely an example, and the present invention relates to such an embodiment. Needless to say, the present invention is not limited to the anti-adhesion / elimination means, and for example, the anti-adhesion / elimination means exemplified below can be similarly employed. Should be understood.

  Specifically, in the above-described embodiment, the round bar-shaped probe 12 has a stepped structure including a thin probe tip 12a and a thick probe base 12b. However, as shown in FIG. In addition, a structure in which a screw portion is formed on the outer peripheral surface of the probe 12 is also possible. Thus, by forming the screw portion 30 on the outer peripheral surface of the probe 12 and projecting the probe 12 from the shoulder member 14, the screw portion of the screw portion 30 enters the gap between the probe 12 and the shoulder member 14. By pushing the adhered metal material (24) to the outside or rotating the probe 12 while projecting, the screw member 30 feeds the metal material (24) that has entered the gap and adhered to the outside. It can be extruded.

  Further, as shown in FIG. 5, by providing a brush 32 so as to slidably contact the outer peripheral surface of the probe 12 protruding from the shoulder member 14, the metal material adhered to the outer peripheral surface of the probe 12 by the friction stir spot joining operation. It is also possible for the probe 24 to be scraped off by the brush 32 while protruding the probe 12 from the shoulder member 14.

  Furthermore, as shown in FIG. 6, a discharge hole 34 is provided so as to penetrate the cylindrical wall portion of the cylindrical shoulder member 14, and the gap between the probe 12 and the shoulder member 14 from the front end surface side of the shoulder member 14. The metal material (24) that has entered the inside may be discharged from the gap through the discharge hole 34.

  In addition, as shown in FIG. 7, using a gas feeding device provided on the base side of the rotary tool 10, the gap 18 between the probe 12 and the shoulder member 14 is moved from the probe base side toward the tip side. It is also possible to push out the metal material (24) that has entered the gap 18 or to prevent entry into the gap 18 by blowing a pressure gas.

  By the way, as a shape of the to-be-joined metal member which performs friction stir spot joining operation using such a rotary tool 10, it is not necessary that the whole is a flat plate material, and at least the superposition part is friction stir spot joining. To the extent possible, it is sufficient to exhibit a flat plate shape. Therefore, various metal plate materials are subjected to various molding operations such as press molding and molded into various shapes. It is also possible to use the product as a metal member to be joined in the present invention, and in addition, the portion other than the overlapped portion is not plate-shaped but has various shapes such as block shape, columnar shape, cylindrical shape, box shape, etc. Can also be used as a metal member to be joined. In addition, the shape of the metal member to be joined located at the lowest part of the overlapped portion is not limited to the plate shape given by the metal plate material as described above, but two superimposed on it. As long as each plate-like part of the metal member to be joined can be placed, a member having a flat surface can be used to attach a member having various shapes such as a block shape or a box shape to the lowermost part of the superposed part. It can be used as a bonding metal member.

  In addition, although not enumerated one by one, the present invention is carried out in a mode to which various changes, modifications, improvements, etc. are added based on the knowledge of those skilled in the art. It goes without saying that any one of them falls within the scope of the present invention without departing from the spirit of the present invention.

  Hereinafter, representative examples of the present invention will be shown to clarify the present invention more specifically, but the present invention is not limited by the description of such examples. It goes without saying.

  First, as a metal member to be joined, two aluminum plates having a thickness of 1 mm (6016-T4 material) were prepared, and then a backing jig was brought into contact with the lower plate, After fixing using a predetermined clamp member, friction stir spot welding was performed using a double-acting rotary tool having two stages as shown in FIG. 1 as the rotary tool. The friction stir spot joining operation is performed by rotating the rotary tool at a high speed, with the shoulder surface of the shoulder member and the tip end surface of the probe being flat (in a state of being flush with each other). Then, the probe is inserted to a depth of 1/3 of the thickness of the lower aluminum plate, friction stir welding is performed, and then the shoulder member is pulled out while pulling the probe out of the aluminum plate. A friction stir spot joint with no probe hole remaining was formed.

  Then, when the friction stir spot joining operation is continuously performed 100 times, aluminum adheres between the probe and the shoulder member, the load for driving the probe increases, the limiter operates, and the device Stopped. Therefore, as shown in FIG. 3, it was confirmed that by sticking the probe out of the shoulder member, the aluminum adhered in the gap was peeled off in a ring shape and removed. Moreover, after removing such agglomerated aluminum, it was confirmed that 100 continuous friction stir spot joining operations were possible.

It is longitudinal cross-sectional explanatory drawing which expands and shows the front-end | tip part of an example of the rotary tool for friction stir spot joining according to this invention. It is process explanatory drawing which shows the process of performing friction stir spot joining using the rotary tool shown by FIG. 1, Comprising: (a), (b) and (c) are explanatory drawings which show one form in each process, respectively. is there. It is process explanatory drawing which shows the discharge | emission process of an intrusion metal material after completion | finish of friction stir spot joining, Comprising: (a), (b), (c) and (d) are explanatory drawings which show one form of the process, respectively. It is. It is sectional explanatory drawing which shows another example of the rotary tool for friction stir spot joining according to this invention, (a) And (b) has each shown a mode that a probe protrudes and the metal material which penetrate | invaded is discharged | emitted. . It is sectional explanatory drawing which shows another example of the adhesion prevention / elimination means in the rotary tool for friction stir spot joining according to this invention. It is sectional explanatory drawing which shows another example of the adhesion prevention / elimination means in the rotary tool for friction stir spot joining according to this invention. It is sectional explanatory drawing which shows another example of the adhesion prevention / elimination means in the rotary tool for friction stir spot joining according to this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rotating tool 12 Probe 12a Probe front-end | tip part 12b Probe base part 14 Shoulder member 16 End surface 18 Crevice 20 Friction stirring area 22 Joining part 24 Metal material

Claims (6)

A plurality of metal members to be joined, and a rod-like probe that is inserted while being rotated from one side of the overlapped portion, and is fitted around and coaxially positioned around the probe, A cylindrical shoulder member having a shoulder surface that is brought into contact with the surface in a rotating state, and the probe and the shoulder member are configured separately and are separately movable in the axial direction. In the rotary tool for friction stir spot welding of dynamic structure,
A double-acting rotary tool for friction stir spot joining, characterized in that it is provided with adhesion preventing / eliminating means for discharging the material of the metal member to be joined that has entered between the probe and the shoulder member to the outside.   The adhesion preventing / eliminating means comprises a stepped portion formed on the outer peripheral surface of the probe and having a larger diameter on the base side than the distal end surface. After the friction stir spot joining operation, the probe The double-acting type for friction stir spot joining according to claim 1, wherein the intruding material is discharged to the outside by rotating or protruding relative to the shoulder member. Rotary tool.   The adhesion preventing / eliminating means is constituted by a screw portion formed on the outer peripheral surface of the probe, and the probe is protruded relative to the shoulder member after the friction stir spot joining operation. The double-acting rotary tool for friction stir spot welding according to claim 1, wherein the intruding material is discharged to the outside.   The adhesion preventing / eliminating means is constituted by brush means capable of sliding on the outer peripheral surface of the probe to remove the adhering intruding material, and after the friction stir spot joining operation, the probe is the shoulder member. The double-acting rotary tool for friction stir spot welding according to claim 1, wherein the brush means is relatively slidably brought into contact with the outer peripheral surface of the protruded probe, and the brush means is brought into sliding contact with the outer peripheral surface of the protruded probe.   The adhesion preventing / eliminating means is constituted by a discharge hole provided so as to penetrate the cylindrical wall portion of the shoulder member, and the intrusion material is discharged to the outside through the discharge hole. The double-acting rotary tool for friction stir spot welding according to claim 1. The adhesion preventing / releasing means is constituted by gas blowing means for blowing gas from the base side toward the tip side into the gap between the probe and the shoulder member, and after the friction stir spot joining operation 2. The double-acting rotary tool for friction stir spot welding according to claim 1, wherein the intrusion material is discharged to the outside by gas blowing by the gas blowing means.

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