JP4672434B2 - Friction stir spot welding method - Google Patents

Description

  The present invention relates to an improved friction stir spot joining method, and in particular, a method in which each plate-like portion of two or more metal members to be joined is superposed on a predetermined metal member to be joined by friction stir welding. It relates to an effective technique for spot joining.

   Conventionally, in the manufacture of automobiles, the body members and various parts are manufactured by superimposing a plurality of metal plate members and connecting them together by point joining such as rivets or resistance spot welding. In addition, the connection method of metal plates by such point joining is used in the field of transportation equipment such as various vehicles such as railway vehicles and aircraft, and in the field of structures such as home appliances and building materials. Has also been widely adopted.

  On the other hand, in Patent Document 1, etc., a friction stir welding method in which a metal member is joined using frictional heat as a joining method with less heat input during joining and less softening or distortion has been proposed. Adopting such a friction stir welding technique, a technique for spot joining the overlapping parts of a plurality of metal plate members has been studied, thereby improving the joint quality compared to conventional resistance spot welding or rivet joining, Various friction stir spot joining methods have been proposed as a good joining state can be stably obtained (see Patent Documents 2 to 5).

  However, all of these proposed friction stir spot joining methods basically use a pin-type tool (rotary tool) having a structure in which a pin-shaped hard probe is provided at the tip of a rod-shaped tool body. By using it, while rotating it at a high speed, it is inserted into the overlapping part of a predetermined metal plate member, and the shoulder part constituted by the tip of the tool body of the pin type tool is pressed against the overlapping part By generating frictional heat between the shoulder or the probe and the superposition site, the material is plastically flowed, and a stirring region is formed around the probe, so that the metal is inserted at the insertion site of such a probe. It is intended to perform point joining of the overlapping parts of the plate members, but the metal plate members that are to be spot-bonded are overlapped in three or more sheets. In the point joining at the position, it becomes difficult to uniformly join these three or more metal plate members. Therefore, the bonding strength (joint strength) is sufficient at the overlapping position of the overlapped metal plate members. There was a problem that it was difficult to secure.

Specifically, when three or more metal plate members are overlapped and the overlapped portion is friction stir spot bonded using the pin type tool as described above, the probe of the pin type tool is inserted. The bonding interface between the outermost plate member (uppermost) plate member and the lower plate member can be sufficiently agitated, so that the bonding strength between these plate members is satisfactory. At the bonding interface between the lower intermediate plate members, and the bonding interface between the intermediate plate member and the bottommost plate member (the lowest step), the influence of frictional heat generation and pressing of the shoulder portion of the pin type tool is not sufficient, For this reason, since the stirring is insufficient and it is difficult to effectively form a stirring region based on plastic flow, the joint strength between the intermediate plate members or between the intermediate plate member and the bottom plate member (joint strength) ) Is not enough . Further, in the case of using a pin type tool in which the probe and the shoulder portion are integrated, the probe portion having a small bottom area is first brought into contact with the outermost portion of the metal plate member to be joined. Therefore, the frictional heat hardly occurs, and the metal pushed out from the stirring portion by inserting the probe until the shoulder portion comes into contact with the outermost portion of the metal plate member to be joined is discharged as burrs and chips. , the material becomes difficult to plastically flow in the stirring section, also sufficient bonding strength is a problem not be obtained, Oh Ru since inherent.

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

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is that each plate shape of two or more metal members to be bonded on a predetermined metal member to be bonded. When the overlapping portions are overlapped and the overlapped portion is spot-bonded by the friction stir welding method, sufficient joint strength (bonding strength) can be ensured at any bonding interface in the overlapping portion of the metal members. Another object of the present invention is to provide a friction stir spot joining method.

And in this invention, in order to solve the above-mentioned subject, each plate-shaped part of two or more to-be-joined metal members is piled up on a predetermined to-be-joined metal member, and these three or more From the side of the plate-like part located at the uppermost part of the overlapped part made of the metal member to be joined, the probe positioned coaxially at the center of the shoulder member of the rotary tool rotated around the axis is inserted while rotating, these three or more in the friction stir spot joining method to be point bonded to the bonded metallic member, as said rotating tool, and said shoulder member and the probe formed separately, the further cross the shoulder member A plurality of cylindrical shoulder members that can be inserted coaxially are arranged, and the plurality of cylindrical shoulder members are sequentially coaxially extrapolated and arranged around the probe, and the probe and the plurality of cylindrical shoulder members are arranged. Da member, using a double-acting rotary tool comprising a movable separately in the axial direction, in a state in which each of the distal end surface of the probe and the shoulder member and flush, while rotating them, said heavy The friction stirrer is characterized in that after the frictional heat generating part is formed on the overlapped part by pressing against the surface of the uppermost plate-like part of the mating part, the probe is inserted and the overlapped part is subjected to friction stir welding The point joining method is the gist thereof.

  Further, according to one of the desirable modes of the friction stir spot joining method according to the present invention, a burr pressing cylinder is extrapolated to the outer peripheral surface of the shoulder member, and the uppermost plate-like portion surface of the superposed portion is placed. By abutting, the generation of burrs around the shoulder member can be suppressed or prevented.

  Furthermore, in another preferable aspect of the friction stir spot joining method according to the present invention, the tip of the probe is inserted into the joined metal member located at the lowest part of the overlapped portion. It has become.

  Thus, according to the friction stir spot joining method according to the present invention, the double-acting rotary tool in which the probe and the shoulder member are configured separately as the rotary tool, and each of them can be moved separately in the axial direction. Since the tip end surfaces of the probe and the shoulder member are flush with each other, the shoulder member and the probe are brought into contact with the outermost portion of the stacked metal members to be joined. Therefore, frictional heat can be generated in a large area while applying an appropriate pressure to the superposed portion to be joined over a wide area, and making the joining interfaces of the metal members to be joined more closely. Thus, the expansion of the softening region that is substantially constituted by the frictional heat generating part is effectively realized, and the generated frictional heat is superposed on the overlapped metal part. The lower plate is also than it is possible allowed to effectively transmitted. In this manner, the softening region is enlarged, and a large stirring region can be formed by inserting the probe in a state where the frictional heat is sufficiently transmitted to the lower metal member to be joined. Therefore, it is possible to sufficiently generate a stirring action at each bonding interface, thereby increasing the bonding strength.

  Further, according to one of the desirable modes of the friction stir spot joining method according to the present invention, the uppermost portion of the plate-like portion where the metal member to be joined is overlapped by extrapolating the burr pressing cylinder on the outer peripheral surface of the shoulder member. The material pushed out from the frictional heat generating part or the friction stirrer around the shoulder member by the insertion of the probe into the frictional heat generating part or the friction agitating part from the surface abutted on the surface of the burr pressing cylinder Due to the contact, the frictional heat generating part or the friction agitating part can be pushed in, so that burrs generated on the surface of the metal member to be joined can be effectively suppressed or prevented.

  Furthermore, according to one of the other preferable aspects of the present invention, each interface is formed by inserting the tip of the probe to the bonded metal member positioned at the lowest part of the overlapped portion of the bonded metal member. Can be sufficiently generated, and the bonding strength can be further improved.

  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 is a conceptual diagram showing an embodiment of a friction stir spot joining method according to the present invention. Therein, 2 is a superposed part of the metal members to be joined that are subjected to friction stir spot joining according to the present invention, and the friction stir spot joining operation using the rotary tool 10 according to the present invention is performed on this superposed part 2. Is now being implemented.

  More specifically, the superposed portion 2 is composed of three metal plates 4a, 4b and 4c, which are metal members to be joined, stacked in the vertical direction, and the three pieces of metal. The overlapping surfaces of the plate members 4a to 4c, that is, the space between the outermost metal plate member 4a and the lower metal plate member 4b serves as a bonding interface 6a, and the metal plate member 4b and the bottom (lowermost) portion. A joint interface 6b is formed between the metal plate member 4c positioned. The three metal plates 4a to 4c are clamped to be fixed in the same manner as in the past in order to perform the desired friction stir spot joining, and the back surface of the lowermost metal plate 4c. Although not shown here, an appropriate backing jig is arranged to support the three metal plates 4a to 4c.

  Further, a steel double-acting rotary tool 10 similar to the conventional one is disposed on the upper side of the three metal plates 4a to 4c that are overlapped. The rotary tool 10 is inserted into the cylindrical outer shoulder member 12, the cylindrical inner shoulder member 14 inserted in the central hole of the outer shoulder member 12, and the central hole of the inner shoulder member 14. The rod-shaped probe 16 is coaxially arranged, and can be rotated at high speeds around their axes, and independently in their axial directions. And can be moved. The shoulder members 12 and 14 and the probe 16 are configured to be actuated in various known double-acting structures, and at least the metal plate of the shoulder members 12 and 14 and the probe 16 is configured. The parts that are in contact with or pressed against 4a to 4c and are inserted are made of a material harder than the metal plates 4a to 4c, so that their wear can be prevented in the friction stir welding operation. ing.

  When the three metal plates 4a to 4c are joined by the friction stir welding method according to the present invention, first, as shown in FIG. 2 (a), the shoulder surface 12a of the outer shoulder member 12 and While the shoulder surface 14a of the inner shoulder member 14 and the tip end surface 16a of the probe 16 are flush with each other, the shoulder surface 12a, 14a and the shoulder surfaces 12a, 14a are rotated as shown in FIG. The front end surface 16a is pressed against the surface of the outermost metal plate 4a so that an appropriate pressure is applied to the overlapped portion 2 of the metal plates 4a to 4c. By such pressing, while joining the bonding interface 6a between the metal plates 4a and 4b and the bonding interface 6b between the metal plates 4b and 4c, in addition, between the metal plate 4a and the distal end surface 16a of the probe 16, Friction heat is also generated between the metal plate 4a and the shoulder surface 12a or the shoulder surface 14a, and the frictional heat is transmitted from the metal plate 4a to the lower metal plate 4b or the metal plate 4c. Then, the frictional heat generated in this way forms the frictional heat generating portion 18 in a wide range as shown in (c), and a part of the outer shoulder member 12 enters the metal plate 4a to some extent. It becomes a state. At this time, the shoulder members 12 and 14 and the probe 16 constituting the rotary tool 10 can be rotated independently of each other as well as being rotated integrally.

  Thus, with the probe 16 being flush with the shoulder members 12, 14, the tip surface of the probe 16 is brought into contact with the surface of the upper metal plate 4a and rotated at high speed around the axis. As a result, it is possible to effectively generate a large range of friction with an area that is as large as possible compared to the case where only the metal plates 4a to 4c are brought into contact with each other. Since pressure can be applied, the generated frictional heat can be more effectively transmitted to the lower metal plates 4b and 4c, thereby forming a large frictional heat generating portion 18 or a softened region. In addition, it is possible to enjoy the advantage of effectively suppressing or preventing the occurrence of burrs at the initial stage of insertion of the probe 16 which has occurred in the past.

  Next, after the frictional heat generating portion 18 is formed, as shown in FIG. 3A, the inner shoulder member 14 and the probe 16 are in a state where the shoulder surface 14a and the distal end surface 16a are flush with each other. It is inserted until it reaches the metal plate 4b. As a result, the friction stirrer 20 is formed in the form in which the frictional heat generating part 18 is expanded to the metal plate 4b. At this time, by slightly raising the outer shoulder member 12 that has entered the metal plate 4a, the metal material pushed out by the insertion of the inner shoulder member 14 and the probe 16 is absorbed and discharged as burrs to the outside. Will be suppressed.

  Thereafter, as shown in FIG. 3B, the probe 16 is projected from the inner shoulder member 14 and inserted until the tip of the probe 16 reaches the lowermost metal plate 4c. As a result, a large friction stirrer 20 is formed across the metal plates 4a to 4c, so that the overlapping portion 2 of the metal plates 4a to 4c is joined to the friction stir spot. Also in this case, similarly to the insertion of the inner shoulder member 14, by raising the inner shoulder member 14 simultaneously with the insertion of the probe 16, the metal material that is stirred and fluidized is effectively absorbed, Exhaust from the friction stirrer 20 to the outside is effectively suppressed. The insertion depth of the probe 16 is appropriately determined according to the thickness of the metal plate 4c.

  Thus, the friction stir welding operation ends as described above. To remove the rotary tool 10 from the state, simply pulling the rotary tool 10 away from the stirring region portion 20 merely requires the inner shoulder member. 14 and the hole from which the probe 16 is removed (probe hole) remains in the friction stirrer 20 as it is, and here, the following process is advantageously employed when the rotary tool 10 is pulled out. The That is, by performing an operation opposite to the above operation from the state shown in FIG. 3B to the state shown in FIG. 2C through the state shown in FIG. 3A, or While raising the inner shoulder member 14 and the probe 16 at the same time or with an appropriate time delay and pulling them out from the friction stirrer 20, the outer shoulder member 12 is lowered and the upper surface of the friction stirrer 20 is pressed by the shoulder surface 12a. By pushing in, the holes generated by the withdrawal of the inner shoulder member 14 and the probe 16 are embedded by the flow of the metal material from other parts of the friction stirrer 20.

  In this way, when the rotary tool 10 is detached from the friction stirrer 20 and the probe hole is completely embedded, as shown in FIG. 3C, the friction stirrer 20 is connected to the inner shoulder member 14 and the probe. The hole formed by 16 is substantially lost. However, such a probe hole need not be completely erased to the extent that a trace remains or cannot be confirmed, so that the bottom at the maximum depth at which the probe 16 is inserted is sufficiently covered. As long as the hole is embedded with a metal material that can be caused to flow from other parts of the friction stirrer 20, there is no problem even if it exists as a hole having a certain depth.

  In addition, as a specific embedding operation of the hole generated by pulling out the probe 16, the inner shoulder member 14 is lowered (pushed) simultaneously with the raising (pulling) of the probe 16, and a little behind the start of the former raising. Thus, an operation such as starting the lowering of the latter or starting the lowering of the latter after completion of the former can be adopted as appropriate, and the rotary tool 10 is detached from the friction stirrer 20. After that, it is also possible to apply a pressing operation with an appropriate pressing member to flow the material from other parts of the friction stirrer 20 so that the probe hole is embedded.

  As described above, according to the friction stir spot joining method according to the present invention, the shoulder members 12 and 14 of the rotary tool 10 rotated at a high speed and the probe 16 are superposed with their front end surfaces being flush with each other. The metal plate 4a, 4b, 4c, which is a metal member to be joined, is pressed against the outermost metal plate 4a and rotated at a high speed, thereby generating frictional heat with a contact area as large as possible and applying the pressing force to the metal The bonding interfaces 6a and 6b between the plates 4a to 4c are brought into close contact with each other, and the frictional heat generated between the shoulder surfaces 12a and 14a and the tip surface 16a and the metal plate 4a is sufficiently applied to the lower metal plates 4b and 4c. Since the friction stir welding is performed in the state of being transmitted to the inside, the largest possible softening region can be effectively formed, and the lower metal plate 4b and the metal plate 4c are also inserted inside A large friction stirrer 20 can be formed around the shoulder member 14 and the probe 16, and the metal material can be sufficiently stirred or plastically flowed at the joint interfaces 6a and 6b. The joining portion has excellent joining strength.

  By the way, the present invention can be advantageously carried out not only in the above-described form but also in the form shown in FIG. That is, in the joining process by the friction stirring method shown in FIG. 4, the cylindrical burr presser cylinder 30 is extrapolated and arranged on the outer peripheral surface of the outer shoulder member 12 of the rotary tool 10. When the burr holding cylinder 30 is lowered, the three metal plates 4a, 4b and 4c, which are supported by the backing jig 32, can be pressed from above.

  In the friction stir welding operation, the burr pressing cylinder 30 is lowered simultaneously with or before the lowering of the shoulder members 12 and 14 and the probe 16 of the rotary tool 10 to lower the upper metal plate 4a. The surface is pressed. Next, the rotary tool 10 is lowered, and the same friction stir welding operation as in the previous example is performed. At this time, the shoulder surface 12a of the outer shoulder member 12 and the shoulder surface 14a of the inner shoulder member 14 are performed. Further, burrs overflowing from the friction stirrer 20 formed by the friction stir action by the probe 16 are prevented by the presence of the burr pressing cylinder 30. However, the outer shoulder member 12 is subjected to the friction stir operation so that the overflow of the burr is prevented and the increase in the volume of the friction stir unit 20 due to being blocked in the friction stir unit 20 can be absorbed. In FIG. 2, the valve is slightly retracted (raised). The burr pressing cylinder 30 is not rotated and is pressed by a spring or the like with a pressing force that does not allow the burr to enter between the upper metal plate 4a.

  Thereafter, when the friction stir operation by the rotary tool 10 is completed, the inner shoulder member 14 and the probe 16 are pulled out (ascended), and the outer shoulder member 12 is pushed down, so that the inner shoulder member 14 and the probe 16 are moved. The drawing hole is embedded by the flow of the metal material from the other part of the friction stirrer 20, and then the pressure against the metal plate 4 a of the burr holding cylinder 30 is released. Thus, the friction stir spot joining of the target three metal plates 4a, 4b, 4c is realized.

  On the other hand, FIG. 3 shows a case where the friction stir spot joining of the superposed portion 2 formed by superposing three metal plate members 4a to 4c as shown in FIG. 1 is performed using a conventional rotary tool. The state corresponding to (a) is shown in FIG. 5, in which the rotary tool R having the same structure as the conventional one is simply concentrically connected to the tip of the rod-shaped tool body B. Since the probe P is only integrally formed, the probe P is inserted into the overlapping portion 2 first, so that the lower end portion (shoulder portion) of the tool body B comes into contact later. -Even if pressed, the frictional heat generation is not sufficient, and the metal flow area is narrow, and therefore the stirring area A formed around the probe P also becomes a wine cup shape and inevitably narrows. Therefore, the upper bonding interface 6a is still The bonding strength to the joint strength at a joint interface 6b of the lower side, is becoming difficult to sufficiently secure. Even if the outer diameter of the shoulder portion of the tool body B that is brought into contact with and pressed against the upper surface of the superposed portion 2 is increased to increase the amount of heat generated by friction, the heat transfer at the joining interface cannot be sufficiently performed. However, sufficient heat supply cannot be made up to the lower bonding interface 6b, and it still becomes a wine cup-shaped stirring region A as shown in the figure, and the bonding strength (joint strength) cannot be sufficiently improved. In addition, problems also arise in the workability of the friction stir spot joining operation.

  The exemplary embodiments of the present invention have been described in detail above. However, the embodiments are merely examples, and the present invention is limited in any way by specific descriptions according to such embodiments. It should be understood that it is not interpreted.

  For example, in the above embodiment, the point joining method to which the present invention is advantageously applied is adopted as the friction stir welding method. However, the rotary tool 10 is relatively fixed to the metal plates 4a, 4b, and 4c to some extent. The present invention can also be applied to a method of moving the friction stir welding.

  In addition, the plurality of metal plate materials that are the metal members to be joined used in the embodiment may be of the same material or different materials, and there is no problem. The material of the plate material is not particularly limited. For example, it is made of a relatively soft metal such as an aluminum member made of aluminum or an alloy thereof, a copper member made of copper or an alloy thereof, or a magnesium member made of magnesium or an alloy thereof. A known material capable of friction stir welding, such as a relatively hard metal member such as iron or steel, is appropriately selected and used.

  Furthermore, the shape of such a metal member to be joined does not have to be a flat plate as a whole, and at least the superposition site thereof should be a flat plate as long as friction stir spot welding is possible. Therefore, a molded product formed into various shapes by performing various molding operations such as press molding on each metal plate material is used as the bonded metal member in the present invention. It is also possible to use a member having various shapes such as a block shape, a column shape, a cylindrical shape, a box shape, and the like as a metal member to be joined, instead of a plate-like portion other than the overlapping portion. is there. 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.

Furthermore, in the above-described embodiment, the rotary tool 10 is a three-stage double-acting rotary tool, but the number of stages is appropriately changed depending on the number and thickness of the metal members to be joined. is, there is employed, for example, it can also be a further double acting rotary tool and more stages of the four stages of the shoulder member tighten let out to the outside of the outer shoulder member 12. Among them, in the present invention, a double-acting structure having the number of stages (adding the probe as one stage) corresponding to the number of metal members to be joined is advantageously used.

  In addition, as such a rotary tool 10, various known double-acting rotary tools can be used as appropriate. Even if the shape or structure of the probe 16 is not limited to a straight cylindrical shape. Any of various known shapes such as a conical shape or a truncated cone shape tapering toward the tip can be adopted, and the surface thereof is provided with protrusions, ridges, grooves or the like. However, there is no problem. Moreover, even if it exists in the shape of the shoulder surfaces 12a and 14a of the end surface of the shoulder members 12 and 14, it is not specifically limited, Even if it is a flat surface, the concave surface shape curved toward the center may be sufficient. Various conventionally known shapes will be adopted as appropriate.

  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.

Example 1
First, as the metal member to be joined, prepare a laminate of three aluminum plates (6016-T4 material) with a plate thickness of 1 mm, and a backing jig is brought into contact with the lowermost plate side, After fixing using a predetermined clamp member, friction stir spot welding was performed using a three-stage double-acting rotary tool configured as shown in FIG. 1 as the rotary tool.

  In this friction stir spot joining operation, while rotating the rotary tool at a high speed, first, the entire shoulder surface and the tip end surface of the probe are flattened (in a state where they are flush), and the outermost part (rotary tool side) ) Is inserted to a depth of 1/3 of the thickness of the aluminum plate, and then the inner shoulder member and probe are extended to a depth of 1/3 of the thickness of the intermediate aluminum plate, and the lowermost (backing treatment) The probe was inserted until the tip of the probe reached a depth of 1/3 the thickness of the aluminum plate on the tool side), and after friction stir welding, the rotating tool was pulled out according to the reverse process. At this time, the retraction operation of the outer shoulder member and the inner shoulder member was performed in the same manner as in FIG.

  Then, when the cross-sectional structure of the obtained joint was investigated, each of the joint interfaces was agitated by the rotary tool, and the oxide at the original interface was sufficiently divided, so that each plate was sufficiently It was recognized that they were joined to each other. Further, the obtained joint was subjected to a tensile test so that a load was applied in parallel to the joint interface, and each joint interface was subjected to shear fracture. As a result, the shear tensile strength was 2 kN. It was confirmed that it was equivalent to the shear tensile strength when two plates having a thickness of 1 mm were joined by friction stir spot welding.

Example 2
4 sheets of aluminum plate (6016-T4 alloy plate material) having a plate thickness of 1 mm are overlaid and a backing jig is brought into contact with the lowermost plate side, while from the uppermost plate side, as shown in FIG. Friction stir spot welding was performed by the following procedure using a four-stage double-acting rotary tool in which another shoulder member was extrapolated on the outer side of the outer shoulder member of the three-stage double-acting rotary tool.

  First, in a state where all the shoulder surfaces and the tip surface of the probe are flat, the rotary tool is rotated at a high speed and inserted to a depth of 1/3 of the thickness of the outermost aluminum plate, and then the state Then, the probe is inserted to the depth of the lowermost bonding interface, that is, the bonding interface between the lowermost aluminum plate and the upper aluminum plate. Next, while pulling out the inserted probe, the outer shoulder member (the innermost one of the three shoulder members) is moved to the depth of the middle interface (the thickness of the four-layer aluminum plate). And then pulling out the shoulder member, the outer shoulder member of the shoulder member (the shoulder member of the second step from the outside of the three shoulder members) Insert it to the depth of the interface between the aluminum plate of the part and the aluminum plate below it. Finally, after pulling out the second shoulder member, the outermost shoulder member is brought into contact with the vicinity of the surface of the outermost aluminum plate member, and then the rotary tool is detached from the metal plate to obtain a friction stirring point. Bonding was performed. The time required for the above bonding operation was 4 seconds.

  Through these steps, it was confirmed that even after the rotary tool was pulled out, it was possible to perform friction stir spot welding without leaving a probe hole on the surface of the outermost aluminum plate.

Comparative Example 1
Three aluminum plates (6016-T4 alloy plate material) with a thickness of 1 mm are stacked, and a backing jig is brought into contact with the lowermost plate side, while the probe as shown in FIG. Using a rotary tool in which the shoulder member is integrally formed, rotate it at a high speed, insert it in 4 seconds until the shoulder reaches 1/3 of the thickness of the outermost plate, and then pull it out. Thus, friction stir spot welding was performed.

  As a result, the stirrer of the bonding interface between the lowermost plate and the intermediate plate is smaller than that of Example 1, and in the tensile test that shears each bonding interface, the outermost plate and the intermediate plate Although the shear tensile strength at the joint interface was 2 kN, it was confirmed that the shear tensile strength at the joint interface between the lowermost plate and the intermediate plate was as low as 0.4 kN.

It is sectional explanatory drawing which shows one state before joining operation of the friction stir spot joining method according to this invention. It is process explanatory drawing which shows the process of the first half of the friction stirring operation in the friction stir spot joining method according to this invention, 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 latter half process following the friction stirring process shown in FIG. 2, Comprising: (a), (b) and (c) are explanatory drawings which show the form in each process, respectively. It is sectional explanatory drawing which shows 1 process of friction stirring operation in another one aspect | mode of the friction stir spot joining method according to this invention. It is sectional explanatory drawing which shows a friction stirring area | region in the case of carrying out the friction stir spot joining of the overlap part of three board | plate materials using the conventional rotary tool.

Explanation of symbols

2 Superposed part 4a, 4b, 4c Metal plate 6a, 6b Joining interface 10 Rotating tool 12 Outer shoulder member 14 Inner shoulder member 16 Probe 18 Friction heating part 20 Friction stirring part 30 Burr holding cylinder 32 Backing jig

Claims (5)

A plate-like portion located on the uppermost part of the overlapped portion made of three or more metal members to be joined by superimposing the plate-like portions of two or more metal members to be joined on a predetermined metal member to be joined. Friction stirrer in which a probe positioned coaxially at the center of a shoulder member of a rotary tool that is rotated around an axis is inserted while being rotated, and three or more metal members to be joined are spot-joined. Use point joining method
As the rotating tool, and said shoulder member and the probe formed separately, further constitute the shoulder member at mutually coaxially insertable plurality of cylindrical shoulder member, said plurality of cylindrical shoulder sequentially coaxially extrapolation about the member probes, with allowed to place, their probes and a plurality of cylindrical shoulder member, using a double-acting rotary tool comprising a movable separately in the axial direction, the probe In the state where the front end surfaces of the shoulder members are flush with each other, the frictional heat generating portion is formed in the overlapped portion by pressing them against the uppermost plate-like surface of the overlapped portion while rotating them. Then, the probe is inserted, and friction stir welding of the superposed part is performed. The friction stir spot welding method according to claim 1, wherein the double-acting rotary tool is composed of the probe and two or three of the cylindrical shoulder members. The friction stir spot welding method according to claim 1 or 2, wherein the total number of probes and cylindrical shoulder members in the double-acting rotary tool corresponds to the number of metal members to be joined. . The burr holding cylinder is extrapolated to the outer peripheral surface of the shoulder member and brought into contact with the uppermost plate-like surface of the overlapped portion, thereby suppressing the generation of burrs around the shoulder member. The friction stir spot welding method according to any one of claims 1 to 3, wherein the friction stir spot welding method can be prevented. The friction stir spot joining method according to any one of claims 1 to 4 , wherein a tip portion of the probe is inserted into a metal member to be joined located at a lowermost portion of the overlapped portion.

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