JP2003326376A - Friction-stirring joined body and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent joined defect from being caused on the joined part in a friction-stirring joined material. <P>SOLUTION: Butted joining part of shape materials 21 and 22 has an engaged structure to be engaged in the width zone direction. Then, at the friction force giving face side with a round shoulder of a bottom tool 11, a plate material 31 in the width zone having not larger than the diameter of the shoulder face, is fixed along the extending direction of the joining part, both long shape materials are subjected to the friction-stirring joining by adding the friction heat to the shoulder face through the plate material. In this case, the interval between one pair of shoulder parts is set so that it is thicker than the joining part but smaller than the thickness plus that of the plate material. Further, the width of the plate is larger than the width of the engaging part formed in the joining part and not larger than the diameter of the shoulder part. Furthermore, the plate material is desirable to be gradually thinned at the injecting tip part of the bobbin tool. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction stir welding mold material and a method for manufacturing the same, and more particularly to a friction stir welding mold material used for a large structure such as a railway vehicle, a ship, and an aircraft, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, a two-sided structure (panel) such as a long hollow material which is used for a large structure such as a railroad car, a ship, and an aircraft and which extends in the longitudinal direction is formed by extruding a plurality of parallel molded products. It is configured by butt-joining the ones arranged in, and when joining such extrusion mold members,
For example, MIG welding or the like may be used to form a butt joint. However, the method of fusion bonding causes problems such as thermal distortion.

On the other hand, Japanese Patent Publication No. 7-505090 discloses the joining of members by friction stir welding. As a solid phase joining method, a rotary tool made of a material substantially harder than a work piece is used. Insert into the joint of the work piece and rotate
There is a joining method in which the workpieces are joined by plastic flow due to frictional heat generated between the rotating tool and the workpiece by moving the tool while rotating.

In the friction stir welding method, since the joining member can be joined while the softened portion is moved by rotating the rotating tool while the joining member is in a solid state, there is no thermal strain and the joining direction is increased. Thus, even a member having a substantially infinite length can be continuously solid-phase bonded in the longitudinal direction. further,
Since the solid phase joining utilizes the plastic flow of metal due to frictional heat between the rotary tool and the joining member, joining can be performed without melting the joining portion. Further, since the joining temperature is low, the deformation after joining is small. Since the joint is not melted, it has many advantages such as few defects.

In such friction stir welding, since welding is performed while pressing with a tool, an extremely large pressing force acts on the welded portion. Therefore, in order to prevent the mold material from being deformed due to the pressing force, a support member for supporting the pressing force is required on the side opposite to the tool.

On the other hand, when performing friction stir welding, a tool having two shoulder portions so as to sandwich a pin (probe) at predetermined intervals from both ends is used as a tool, and the welding portion is joined by the two shoulder portions. The mold members are joined so as to be sandwiched from the front and back directions. According to this method, the pressing force is extremely small because the joint portion is sandwiched by the two shoulder portions from the front surface and the back surface, and the above-mentioned supporting member and the like are unnecessary.

However, when a tool having two shoulder portions (referred to as a bobbin tool) is used, if there is a gap between the gap between the shoulder portions and the joint portion, no pressure is applied to the joint portion, so that a cavity-like shape is obtained. Defects will occur. When the distance between the shoulder portions and the thickness of the joint portion are the same, the joint portion is thinner than the thickness other than the joint portion. Therefore, a problem may occur in the quality of the joint.

If a gap is present in the joint, the gap cannot be replenished when joining the joint using the bobbin tool, and a joint defect may occur.

In order to deal with such a problem, for example, the one described in Japanese Patent Application Laid-Open No. 2002-18580 is known (hereinafter referred to as a conventional example). In the conventional example, the joining is performed by making the joining thickness of the joining material sandwiched between the upper and lower shoulders larger than the distance between the upper shoulder and the lower shoulder. Specifically, in the conventional example, the joining portion of two joining materials facing each other is set as a fitting structure, the thickness of the joining is locally thicker than the thickness other than the joining portion, and the thickness of the joining portion is further increased. It is larger than the gap between the upper and lower shoulders. This prevents the gap of the joint portion from changing due to frictional heat, and also prevents the thickness of the joint portion after joining from becoming thinner than other portions.

[0010]

However, in the conventional example, it is necessary to locally make the thickness of the joint locally larger than the distance between the upper and lower shoulders beforehand. Considering that the gaps that occur in the joints are different, it is difficult to know in advance how thick the joints should be compared to the portions other than the joints. In other words, considering the gap, it is extremely difficult to locally make the thickness of the joint part larger than the gap between the upper and lower shoulder parts in advance. Even if the gap is locally made larger than the gap, the gap may not be sufficiently filled in the joining process. Therefore, a bonding defect may occur.

It is an object of the present invention to provide a friction stir welding material which does not cause welding defects and a method for producing the same.

[0012]

According to the present invention, a circular shoulder that applies frictional heat to a work piece is rotated while applying frictional heat to the front side or front and back sides of a butt joint between mold members extending in the longitudinal direction. In the friction stir welding material that is formed by plastically flowing near the joint portion to perform friction stir welding of the workpieces, the butt joint portion of the mold members is fitted in the width direction or the height direction. In the fitting structure, a plate member having a width less than or equal to the diameter of the shoulder surface is fixed on the frictional force imparting surface side of the joint portion with the circular shoulder, and the shoulder surface is fixed along the extending direction of the joint portion. The friction stir welding material is obtained in which the mold materials are welded to each other while the friction heat is applied to the welding portion via the plate material and the welding portion is plastically flowed.

According to this invention, the mold members are fitted to each other at their joints, and the plate member having a width less than the diameter of the shoulder surface is fixed to the frictional force imparting surface side along the extending direction of the joints. Therefore, the thickness of the plate material and the like can be easily set according to the gap of the joint portion, and as a result, the gap can be sufficiently filled in the joining process. Therefore, no joint defect occurs.

In the present invention, the tool is preferably a bobbin tool having a pair of shoulder portions located on both front and back sides of the joint with the probe interposed therebetween, and the plate member is formed such that the distance between the pair of shoulder portions is equal to or greater than the thickness of the joint. It is set smaller than the added thickness. With this configuration, sufficient frictional heat can be applied from the shoulder portion to the joint via the plate material, and good friction stir welding can be performed.

In the present invention, the plate material is preferably made of the same material as the mold material or a material having a lower melting point than that of the mold material, and the fixing is performed by an adhesive having a lower evaporation temperature than the temperature caused by the friction heat or by spot welding. It is fixed to the joint. In this way, if the plate material is made of the same material as the mold material or a material having a lower melting point than that, the plate material is friction stir welded together with the mold material, and moreover, the plate material and the mold material are fixed with an adhesive. For example, the adhesive can be easily fixed, and since the evaporation temperature of the adhesive is lower than the temperature due to frictional heat, the adhesive evaporates in the process of friction stir welding, so there is no problem. Furthermore, if the plate member and the mold member are fixed by spot welding, temporary fixing can be easily performed.

In the present invention, it is preferable that the cross-sectional area of the plate member is 1 to 3 times the total area of the fitting gap generated in the joint. By defining in this way, it is possible to perform good friction stir welding. Even if the thickness of the plate member is set to be 1 time or more and 3 times or less of the fitting gap generated in the joining portion, good friction stir welding can be similarly performed.

In the present invention, it is preferable that the width of the plate member is not less than the width of the fitting portion formed at the joint and not more than the shoulder diameter. Here, since the width of the plate material is set to be equal to or larger than the width of the fitting portion formed in the joint portion and equal to or smaller than the shoulder diameter, the plate material does not protrude from the shoulder portion (that is, the tool), and the friction stir welding should be performed well. You can

According to the present invention, the tool projecting end of the plate material is gradually thinned. By doing so, it is possible to easily insert a tool such as a bobbin tool at the starting point of the joining portion during friction stir welding.

Further, according to the present invention, a circular shoulder for applying frictional heat to a workpiece is rotated while applying frictional heat to the front side or front and back sides of a butt joint between mold members extending in the longitudinal direction, In a manufacturing method for forming a friction stir welding material by performing friction stir welding of workpieces while plastically flowing in the vicinity of the joint portion, the butt joint portion of the long shape members is fitted in the width direction or the height direction. And a plate member having a width less than or equal to the diameter of the shoulder surface is fixed to the frictional force imparting surface side of the joining portion with the circular shoulder, and the shoulder surface is fixed. Frictional heat of the above is applied to the joint portion through the plate material,
A method for producing a friction stir welding material is obtained, in which the joining portions are plastically fluidized to join the mold members together. Also in this manufacturing method, for example, the tool is a bobbin tool having a pair of shoulder portions located on both front and back sides of the joint portion with the probe interposed therebetween, and the plate material is provided with a gap between the pair of shoulder portions being equal to or greater than the thickness of the joint portion. May be set to a smaller thickness than the above, and the plate material is made of the same material as the mold material or a material having a lower melting point than that of the die material, and its fixing is performed at an evaporation temperature lower than the temperature due to the friction heat. Alternatively, it may be fixed to the joint with an agent or spot welding.

In addition, the width of the plate member is not less than the width of the fitting portion formed at the joint portion and not more than the shoulder diameter, so that the fitting portion can be fitted by the separating / connecting operation in the width direction. And
It is desirable that the tool projecting end of the plate material be gradually thinned.

[0021]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings. It should be noted that the dimensions, materials, shapes, relative arrangements, and the like of the components described in the illustrated examples are not intended to limit the scope of the present invention thereto unless otherwise specified, but are merely illustrative examples. Absent.

Referring to FIG. 1, the illustrated tool 11 has a thin probe 12 and a pair of shoulder portions 13 and 14 having a circular cross section which sandwiches the probe 12, and such a tool is called a bobbin tool. On the lower surface of the shoulder portion 13 and the upper surface of the shoulder portion 14, circular shoulder surfaces 13a and 1
4a has been generated, and the shoulder surfaces 13a and 14a apply frictional heat to the butt joint between the mold members, which are the workpieces, as will be described later.

As shown, the diameter (A) of the shoulder portions 13 and 14 is larger than the diameter of the probe 12, and the distance between the shoulder portions 13 and 14 (that is, the distance between the shoulder surfaces 13a and 14a) (B) is It is set in accordance with the thickness of the plate material and the thickness of the butt joint portion described later.

With reference to FIG. 2, description will be given here on joining of long-shaped members used in, for example, a railway vehicle. The long mold members 21 and 22 are, for example, extruded mold members having a U-shaped cross section and made of an aluminum alloy. In the illustrated example, the mold material (long mold material) 21 extends in the longitudinal direction (in FIG. 2, the direction from the front side to the back side (long direction) of the paper surface) (for example, about 25 meters), and the face plate portion 21a and 21b is provided. These face plate portions 21a and 21b
Are held at predetermined intervals by rib members 21c arranged perpendicularly to the face plate portions 21a and 21b. A joint portion is defined at one end portion (right side in the drawing) of the long mold member 21, and a fitting groove 21d having a concave shape in the width direction is formed at this one end portion (that is, one end portion of the face plate portions 21a and 21b). There is. The fitting groove extends in the lengthwise direction.

Similarly, the long die member 22 extends in the longitudinal direction and has face plate portions 22a and 22b. The face plate portions 22a and 22b are held at predetermined intervals by a rib member 22c arranged perpendicularly to the face plate portions 22a and 22b. A joint portion is defined at one end portion (left side in the drawing) of the long mold member 22. A fitting protrusion 22d having a convex shape in the width direction is formed on this one end (that is, one end of the face plate portions 22a and 22b), and the fitting protrusion extends in the longitudinal direction.

When the long members 21 and 22 are joined by friction stir welding, the long members 21 and 22 are fixed on a mount (not shown), and the fitting protrusions 22d are fitted in the fitting grooves 21d.
And the long members 21 and 22 are combined (butted). That is, the long mold members 21 and 22 are combined by the fitting structure. At this time, a fitting gap (fitting gap) is inevitably generated. When such a fitting gap occurs, as described above, a defective joint may occur due to the fitting gap. Therefore, the plate member 31 is previously fixed along the joint portion along the extending direction of the joint portion. The plate member 31 is made of the same material as the long-sized members 21 and 22, or a material having a lower melting point than the long-shaped members 21 and 22,
When fixing the plate member 31, the plate member 31 is fixed using an adhesive whose evaporation temperature is lower than the temperature of the frictional heat applied by the bobbin tool 11.

In FIG. 2, the plate member 31 is fixed to the front surface side of the joint portion, but the plate member 31 may be fixed to the rear surface side of the joint portion along the joint portion. That is, the plate material 31 is fixed to the frictional force application surface side on which the bobbin tool 11 applies the frictional force.

Now, with reference also to FIGS. 3 and 4,
When the fitting width is G and the width of the plate member 31 is C, G <C ≦ A
(A is the diameter of the shoulder portions 13 and 14).
Further, the thickness of the joint, that is, the long mold members 21 and 22
Thickness (in other words, the face plate portions 21a, 21b, 22
When the thicknesses of a and 22b) are D and the thickness of the plate member 31 is E, D ≦ B (B is the distance between the shoulder portions 13 and 14), and further, 2 × E + D> B is set.

When performing the friction stir welding, the bobbin tool 11 is moved from the starting point S of the joining portion extending in the longitudinal direction to the end point (not shown). In the illustrated example, the bobbin of the plate member 31 is moved. The tool entry end is gradually thinned into a knife edge. That is, the plate material 31 is inclined in a knife-edge shape so that the thickness thereof becomes thinner toward the front at the starting point S (that is, the starting point S is an inclined end).

Now, the probe 12 and the pair of shoulder portions 13 and 14 are integrally rotated (for example, in the direction indicated by the thick arrow in FIG. 4), and the bobbin tool 11 is inserted from the starting point S. At this time, as described above, since the plate member 31 is inclined in a knife-edge shape so that the wall thickness thereof becomes thin, at the start point S, the thickness of the joint portion is substantially equal to D. Since D ≦ B, the bobbin tool 1 can be easily
1 could be inserted into the joint.

The bobbin tool 11 is moved along the joint while rotating. As described above, since the plate member 31 is inclined in a knife edge shape so that the wall thickness thereof becomes thin, after the start point S, the total thickness of the plate member 31 and the thickness of the joint portion is equal to the shoulder portions 13 and 14. The distance becomes gradually larger than the interval of, and as a result, the frictional force is applied to the joint portion by the shoulder portions 13 and 14 via the plate member 31. Then, after passing through the projecting end (that is, the tip end portion of the plate material 31), the total thickness of the joint portion and the plate material 31 is 2 ×.
As E + D, a strong frictional force is applied to the plate material 31, and the joint portion is bonded to the plate material 3 by frictional heat and a stirring action.
Friction stir welding will be performed together with 1.

At this time, the fitting gap is filled with the plate material 31 from the front surface side and the back surface side of the joint portion. Further, since the evaporation temperature of the adhesive is lower than the temperature due to the frictional heat applied by the bobbin tool 11, when the friction stir welding is performed, the adhesive is evaporated and the quality is not affected.

According to experiments by the inventors, as described above,
When the friction stir welding was performed by varying G <C ≦ A and D ≦ B <2 × E + D while changing the cross-sectional areas of the two plate members 31, this cross-sectional area was measured at the joint. If the total area of the generated fitting gap is 1 to 3 times,
It was found that it was possible to satisfactorily perform friction stir welding by filling the fitting gap.

It has been found that even if the total thickness of the plate members 31 is 1 to 3 times the fitting gap width generated in the joining portion, the fitting gap can be filled and the friction stir welding can be performed well. In friction stir welding, for example, the rotation speed of the bobbin tool 11 is 800 to 2000 rpm, and the feed speed (moving speed of the bobbin tool 11) is 100 to 1000 mm /
Considered as minutes.

In this way, the face plate portions 21a and 22a
After friction stir welding with the groove, invert and in the same manner,
The face plate portions 21b and 22b are friction stir welded, and the long mold members 21 and 22 are made into long friction stir welders by friction stir welding.

In the above example, the adhesive was used to fix the plate material 31, but the plate material 3 is spot-welded.
1 may be temporarily fixed to the joint portion.

In the above-mentioned example, an example in which the fitting groove 21d which is concave in the width direction and the fitting projection 22d which is convex in the width direction are used as the fitting structure has been described, but the fitting structure shown in FIG. 5 is used. You may That is, while forming the concave fitting groove 41a in the thickness (height) direction at one end of the face plate portion 21a,
A fitting protrusion 41b that is convex in the thickness direction is formed. Similarly, the fitting protrusion 4 that is convex in the thickness direction is formed at one end of the face plate portion 22a.
2a is formed, and the fitting groove 42b is concave in the thickness direction.
To form. Although not shown, the face plate portions 21b and 22b are similarly formed with a fitting groove concave in the thickness direction and a fitting protrusion convex in the thickness direction. Then, as shown in FIG. 5, the fitting protrusion 42a is fitted in the fitting groove 41a, and the fitting protrusion 41b is fitted in the fitting groove 42b to combine the long-sized members 21 and 22 ( Butt). Then, as described above, the plate member 31 is fixed along the joining portion, and friction stir welding is performed.

Further, the fitting structure shown in FIG. 6 may be used. That is, one end of the face plate portion 21a is provided with a notch in the thickness direction from the back surface side thereof to form the locking projection 51, and one end of the face plate portion 22a is notched in the thickness direction from the front surface side. Is provided to form the locking piece portion 52. Although not shown, the face plate portions 21b and 22b are similarly formed with the locking projections and the locking pieces. Then, as shown in FIG.
Alternatively, the long members 21 and 22 may be combined (butted) with each other. Then, as mentioned above,
The plate member 31 is fixed along the joint, and friction stir welding is performed.

In the above example, the bobbin tool is used as the tool, but when friction stir welding is performed using a tool in which a probe is vertically installed on one shoulder portion, the plate material is similarly attached to the joint portion. Is fixed and frictional heat is applied through the plate material. In other words, the bobbin tool cannot be used when there is a member (rib member or the like) that receives a pressing force from the shoulder portion at the joint portion, but even at this time, the probe was vertically installed on one shoulder portion. The plate material may be fixed to the joint using a tool and frictional heat may be applied through the plate material.

[0040]

As described above, according to the present invention, as a fitting structure in which a butt joint between mold members is fitted in the width direction or the height direction, a frictional force imparting surface side of the joint with a circular shoulder is provided. In addition, by fixing the plate material in the width range less than the diameter of the shoulder surface along the extending direction of the joint, the frictional heat of the shoulder surface is applied to the joint through the plate, and the mold members are plastically flowed between the mold members. Since the joining is performed, it is possible to easily set the thickness of the plate material according to the gap (gap) of the joining portion, and as a result, it is possible to sufficiently fill the gap in the joining process. There is no bonding defect.

Further, the present invention uses, as a tool, a bobbin tool having a pair of shoulder portions located on both front and back sides of a joint portion with a probe interposed therebetween, and a distance between the pair of shoulder portions is equal to or larger than a thickness of the joint portion. Since the thickness is set to be smaller than the thickness including the plate material, there is an effect that sufficient friction heat can be applied from the shoulder portion to the joint portion through the plate material, and the friction stir welding can be performed well.

Further, according to the present invention, the plate material is made of the same material as the mold material or a material having a lower melting point than that of the mold material, and the plate material is fixed by an adhesive having an evaporation temperature lower than the temperature by frictional heat or spot welding. Therefore, the plate material is friction stir welded together with the mold material, and moreover, if the plate material and the mold material are fixed with an adhesive, they can be easily fixed. Since the temperature is lower than the above temperature, the adhesive evaporates during the process of friction stir welding and does not affect the quality. Even if the plate member and the mold member are fixed by spot welding, temporary fixing can be easily performed.

Further, according to the present invention, since the cross-sectional area of the plate material is set to 1 to 3 times the total area of the fitting gap generated in the joint,
There is an effect that good friction stir welding can be performed. In addition, the thickness of the plate material can be adjusted to 1
If it is set at least twice and not more than three times, similarly, there is an effect that good friction stir welding can be performed.

Further, according to the present invention, since the width of the plate material is set to be larger than the width of the fitting portion formed at the joint portion and equal to or smaller than the shoulder diameter, the plate material does not protrude from the shoulder portion, and good friction stir welding can be performed. There is an effect that can be.

Further, according to the present invention, since the tool projecting end of the plate material is gradually thinned, it is possible to easily insert a tool such as a bobbin tool at the starting point of the joining portion during friction stir welding. There is.

[Brief description of drawings]

FIG. 1 is a side view showing an example of a bobbin tool used in friction stir welding according to the present invention.

FIG. 2 is a perspective view showing a state in which a plate member is fixed to a butt joint between mold members.

FIG. 3 is a cross-sectional view showing a state in which friction stir welding is performed using the bobbin tool shown in FIG.

FIG. 4 is a cross-sectional view showing an example of a state in which butt joints of mold materials are friction stir welded.

FIG. 5 is a cross-sectional view showing another example of a state in which butt joints of mold materials are friction stir welded.

FIG. 6 is a cross-sectional view showing still another example of a state in which butt joints of mold materials are friction stir welded.

[Explanation of symbols]

11 tools (bobbin tools) 12 probes 13,14 Shoulder part 21,22 type material (long type material) 31 plate material

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuhiro Kanagawa             Hiroshima Prefecture Mihara City Itozakicho 5007 Mitsubishi Heavy Industries             Mihara Machinery & Transportation Systems Factory (72) Inventor Hiromi Etsumi             4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima Mitsubishi             Heavy Industry Co., Ltd. Hiroshima Laboratory (72) Inventor Yukio Manabe             4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima Mitsubishi             Heavy Industry Co., Ltd. Hiroshima Laboratory F-term (reference) 4E067 AA05 BG00 CA01 DA13 DA14                       DA17 DC07 EA06 EA08 EA10                       EC01

Claims (12)

[Claims] 1. A circular shoulder for applying frictional heat to a workpiece is rotated while applying frictional heat to the front side or front and back sides of a butt joint between mold members extending in the longitudinal direction, while rotating the vicinity of the joint. In a friction stir welding material formed by performing a friction stir welding between the workpieces by plastic flow, a butt joint between the mold members is a fitting structure fitted in the width direction or the height direction, A plate member having a width less than or equal to the diameter of the shoulder surface is fixed along the frictional force imparting surface side with the circular shoulder of the joint portion along the extending direction of the joint portion, and the friction heat of the shoulder surface is passed through the plate material. The friction stir welding material is characterized in that the mold members are joined to each other while being added to the joining portion to plastically flow the joining portion. 2. The tool is a bobbin tool having a pair of shoulders located on both front and back sides of the joint with the probe interposed therebetween, and the plate member is added when the distance between the pair of shoulders is equal to or larger than the thickness of the joint. The friction stir welding material according to claim 1, wherein the friction stir welding material is set to have a smaller thickness. 3. The plate material is made of the same material as the mold material or a material having a lower melting point than that of the mold material, and the fixing is performed by an adhesive whose evaporation temperature is lower than the temperature caused by the friction heat or by the spot welding. The friction stir welding material according to claim 1, wherein the friction stir welding material is fixed to the portion. 4. The friction stir welding material according to claim 1, wherein a cross-sectional area of the plate material is 1 or more and 3 times or less of a total area of a fitting gap generated in the joining portion. 5. The friction stir welding material according to claim 1, wherein the thickness of the plate material is not less than 1 time and not more than 3 times the clearance between the joint surfaces generated in the joint portion. 6. The friction stir welding material according to claim 1, wherein a width of the plate member is equal to or more than a width of a fitting portion formed in the joint portion and is equal to or less than a shoulder diameter. 7. The friction stir welding material according to claim 1, wherein a tool projecting end of the plate material is gradually thinned. 8. A circular shoulder for applying frictional heat to a workpiece is rotated while applying frictional heat to the front side or front and back sides of a butt joint between mold members extending in the longitudinal direction, thereby rotating the vicinity of the joint. In a manufacturing method for forming a friction stir welding material by performing friction stir welding between workpieces while plastically flowing, a fitting structure in which the butt joint portion of the mold members is fitted in the width direction or the height direction, A plate member having a width smaller than the diameter of the shoulder surface is fixed to the frictional force imparting surface side of the joint portion with the circular shoulder along the extending direction of the joint portion, and the friction heat of the shoulder surface is A method for producing a friction stir welding material, characterized in that, in addition to the joining portion via a plate material, the joining portion is plastically fluidized to join the mold members to each other. 9. The tool is a bobbin tool having a pair of shoulder portions located on both front and back sides of the joint with the probe interposed therebetween, and the distance between the pair of shoulder portions is larger than the thickness of the joint, and the plate material is added. The friction stir welding material manufacturing method according to claim 8, wherein the thickness is set smaller than the thickness. 10. The plate material is made of the same material as the mold material or a material having a lower melting point than that of the mold material, and the fixing is an adhesive whose evaporation temperature is lower than the temperature due to the frictional heat or the spot welding. The method for producing a friction stir welding material according to claim 8, wherein the friction stir welding material is fixed to 11. The method for producing a friction stir welding material according to claim 8, wherein the width of the plate material is set to be not less than the width of the fitting portion formed at the joint portion and not more than the shoulder diameter. 12. The method for producing a friction stir welding material according to claim 8, wherein the tool projecting end of the plate material is gradually thinned.