JP7413690B2 - Joining method - Google Patents

Description

The present invention relates to a joining method.

Friction stir welding is known as a technique for joining metal members together. Friction stir welding has a problem in that when a stirring pin provided on a rotating tool is pulled out from a metal member, a pull-out hole remains. Therefore, a joining method is known that does not leave any pull-out holes in the metal members.

For example, a joining method according to Patent Document 1 discloses a method in which the stirring pin is gradually pulled out while moving, thereby reducing the pullout marks.

Japanese Patent Application Publication No. 2016-87649

However, the joining method of Patent Document 1 has a problem in that when the rotary tool is gradually pulled out, pull-out marks remain in the plasticized region.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a joining method that can prevent the occurrence of pull-out holes and pull-out marks when joining a main body having a recessed portion and a lid member by friction stirring.

The present invention provides a joining method for joining a main body having a recessed portion and a lid member for sealing an opening of the recessed portion by friction stirring, and a rotary tool used in the friction stirring has a base end pin and a distal end pin. The taper angle of the proximal pin is larger than the taper angle of the distal pin, a stepped portion is formed on the outer peripheral surface of the proximal pin, and the main body has a bottom portion. and a peripheral wall portion rising from a peripheral edge of the bottom portion, and a peripheral wall stepped portion having a stepped bottom surface that is one step lower from an end surface of the peripheral wall portion on an inner peripheral wall of the peripheral wall portion, and a stepped side surface that rises from the stepped bottom surface. an approach part whose lower end contacts the end surface of the peripheral wall part and is gently curved and inclined while changing direction; and an inclined surface which is a slope that contacts the upper end of the approach part and gradually rises. The step side surface of the peripheral wall step portion and the side surface of the lid member are separated by a preparation step of preparing a main body having a slope close to the stepped side surface and by placing the lid member on the main body. a mounting step of abutting against each other to form a first abutting portion, and overlapping the bottom surface of the stepped portion of the peripheral wall step portion with the back surface of the lid member to form a second abutting portion; The rotary tool is inserted into one abutment part, and the rotary tool is moved along the first abutment part with the outer circumferential surface of the proximal pin in contact with the end face of the peripheral wall part and the surface of the lid member to perform friction stirring. After performing this, the rotary tool is moved to the approach section, and while being moved from the approach section to the inclined surface, the distal end pin is moved upward along the inclined surface, and the tip side pin is moved upwardly along the inclined surface. The present invention is characterized in that it includes a main joining step of pulling out the tip side pin above the main joining step, and an inclined table removal step of removing the inclined table after the main joining step.

Further, the present invention provides a joining method for joining a main body having a recess and a lid member for sealing an opening of the recess by friction stirring, and a rotary tool used in the friction stirring includes a proximal pin and a distal end pin. a side pin, the taper angle of the proximal pin is larger than the taper angle of the distal pin, a stepped portion is formed on the outer peripheral surface of the proximal pin, and the main body , a peripheral wall step having a bottom portion and a peripheral wall portion rising from a peripheral edge of the bottom portion, and having a stepped bottom surface that is one step lower from an end surface of the peripheral wall portion on an inner peripheral wall of the peripheral wall portion, and a stepped side surface rising from the step bottom surface. an approach part whose lower end contacts the surface of the lid member and is gently curved and inclined while changing direction; and an inclined surface which is a slope that contacts the upper end of the approach part and gradually rises. a preparation step of preparing a lid member having a slope close to a side surface of the lid member, and placing the lid member on the main body so that the stepped side surface of the peripheral wall step portion and the lid a placing step of abutting the side surfaces of the members to form a first abutting portion, and overlapping the step bottom surface of the peripheral wall step portion and the back surface of the lid member to form a second abutting portion; Inserting a side pin into the first abutment part, and moving the rotary tool along the first abutment part with the outer circumferential surface of the proximal pin in contact with the end face of the peripheral wall part and the surface of the lid member. After moving and performing friction stirring, the rotary tool is moved to the approach section, and while being moved from the approach section to the inclined surface, the tip end side pin is moved so as to rise along the inclined surface. The present invention is characterized in that it includes a main joining step of pulling out the tip side pin above the inclined surface, and a ramp removal step of removing the ramp after the main joining step.

According to this welding method, after friction stir welding is performed, the tip side pin can be pulled out using a tilt table provided at a position different from the first abutting portion. Moreover, the ramp can be cut out from the peripheral wall or the lid member. Thereby, it is possible to prevent the occurrence of a pull-out hole and a pull-out mark caused by the tip side pin. Further, according to this joining method, since friction stirring is performed with the outer circumferential surface of the proximal pin having a large taper angle in contact with the end surface of the peripheral wall and the surface of the lid member, it is possible to suppress the generation of burrs. can.

According to the present invention, when a main body having a concave portion and a lid member are joined by friction stirring, it is possible to prevent the occurrence of a pull-out hole and a pull-out mark.

FIG. 1 is a side view showing a rotary tool according to an embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view of the rotary tool. It is a sectional view showing a first modification of a rotary tool. It is a sectional view showing a second modification of the rotary tool. It is a sectional view showing a third modification of a rotary tool. FIG. 3 is an exploded perspective view showing a preparation step of the joining method according to the first embodiment of the present invention. It is a sectional view showing a mounting process of a joining method concerning a first embodiment of the present invention. It is a top view showing the main joining process of the joining method concerning a first embodiment of the present invention. It is a sectional view showing the main joining process of the joining method concerning a first embodiment of the present invention. It is a perspective view of the end position of the main joining process of the joining method concerning a first embodiment of the present invention. It is a sectional view of the end position of the main joining process of the joining method concerning a first embodiment of the present invention. FIG. 7 is a perspective view showing a joining method according to a second embodiment of the present invention. It is a perspective view showing the joining method concerning a third embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to figures and the like. In addition, in the following description, the surface opposite to the "back surface" will be referred to as the "front surface."

First, a rotary tool used in the joining method according to this embodiment will be explained. A rotary tool is a tool used for friction stir welding. As shown in FIG. 1, the rotary tool F is made of tool steel, for example, and mainly includes a base shaft portion F1, a proximal pin F2, and a distal pin F3. The base shaft portion F1 has a cylindrical shape and is a portion connected to the main shaft of the friction stirrer.

The proximal pin F2 is continuous with the base shaft portion F1 and tapers toward the distal end. The proximal pin F2 has a truncated cone shape. The taper angle A of the proximal pin F2 may be set as appropriate, and is, for example, 135 to 160°. When the taper angle A is less than 135° or more than 160°, the bonded surface roughness after friction stirring becomes large. The taper angle A is larger than the taper angle B of the tip end pin F3, which will be described later. As shown in FIG. 2, a step-like pin stepped portion F21 is formed on the outer peripheral surface of the proximal pin F2 over the entire height direction. The pin step portion F21 is spirally formed clockwise or counterclockwise. That is, the pin stepped portion F21 has a spiral shape when viewed from above, and has a stepped shape when viewed from the side. In the first embodiment, in order to rotate the rotary tool F clockwise, the pin stepped portion F21 is set counterclockwise from the base end side to the distal end side.

In addition, when rotating the rotary tool F to the left, it is preferable to set the pin step part F21 clockwise from the base end side to the distal end side. As a result, the plastic flow material is guided to the tip side by the pin stepped portion F21, so it is possible to reduce metal overflowing to the outside of the metal members to be welded. The pin step portion F21 includes a step bottom surface F21a and a step side surface F21b. The distance X1 (horizontal distance) between the vertices F21c and F21c of the adjacent pin step portions F21 is appropriately set according to the step angle C and the height Y1 of the step side surface F21b, which will be described later.

The height Y1 of the stepped side surface F21b may be set as appropriate, and is set to, for example, 0.1 to 0.4 mm. When the height Y1 is less than 0.1 mm, the bonding surface roughness becomes large. On the other hand, if the height Y1 exceeds 0.4 mm, the bonding surface roughness tends to increase, and the number of effective step portions (the number of pin step portions F21 in contact with the metal member to be welded) also decreases.

The step angle C formed between the step bottom surface F21a and the step side surface F21b may be set as appropriate, but is set to 85 to 120 degrees, for example. In this embodiment, the step bottom surface F21a is parallel to the horizontal plane. The step bottom surface F21a may be inclined within a range of -5° to 15° with respect to the horizontal plane from the rotation axis of the tool toward the outer circumference (minus indicates downward with respect to the horizontal plane, positive indicates downward with respect to the horizontal plane). above). The distance X1, the height Y1 of the step side surface F21b, the step angle C, and the angle of the step bottom surface F21a with respect to the horizontal plane are such that when friction stirring is performed, the plastic fluid material does not stay inside the pin step portion F21 and adhere to the outside. It is appropriately set so that the joint surface roughness can be reduced by pressing the plastic flow material at the bottom surface F21a of the step.

As shown in FIG. 1, the distal pin F3 is formed continuously from the proximal pin F2. The tip side pin F3 has a truncated cone shape. The tip of the tip side pin F3 is a flat surface F4 perpendicular to the rotation axis. The taper angle B of the distal pin F3 is smaller than the taper angle A of the proximal pin F2. As shown in FIG. 2, a spiral groove F31 is carved on the outer circumferential surface of the tip end pin F3. The spiral groove F31 may be clockwise or counterclockwise, but in the first embodiment, in order to rotate the rotary tool F clockwise, it is carved counterclockwise from the base end toward the distal end.

In addition, when rotating the rotary tool F counterclockwise, it is preferable to set the spiral groove F31 clockwise from the base end side to the distal end side. As a result, the plastic flow material is guided to the tip side by the spiral groove F31, so it is possible to reduce metal overflowing to the outside of the metal members to be welded. The spiral groove F31 includes a spiral bottom surface F31a and a spiral side surface F31b. The distance (horizontal distance) between the vertices F31c and F31c of adjacent spiral grooves F31 is defined as length X2. The height of the spiral side surface F31b is defined as a height Y2. The spiral angle D formed by the spiral bottom surface F31a and the spiral side surface F31b is, for example, 45 to 90 degrees. The spiral groove F31 has the role of increasing frictional heat by contacting the metal member to be welded and guiding the plastic fluid material to the tip side. Further, the rotary tool F may be attached to a robot arm having a rotary drive means such as a spindle unit at its tip.

The design of the rotary tool F can be changed as appropriate. FIG. 3 is a side view showing a first modification of the rotary tool of the present invention. As shown in FIG. 3, in the rotary tool FA according to the first modification, the step angle C between the step bottom surface F21a and the step side surface F21b of the pin step portion F21 is 85 degrees. The step bottom surface F21a is parallel to the horizontal surface. In this way, the step bottom surface F21a is parallel to the horizontal plane, and the step angle C may be an acute angle within a range where the plastic fluid material stays in the pin step portion F21 during friction stirring and escapes to the outside without sticking. .

FIG. 4 is a side view showing a second modification of the rotary tool of the present invention. As shown in FIG. 4, in the rotary tool FB according to the second modification, the step angle C of the pin step portion F21 is 115°. The step bottom surface F21a is parallel to the horizontal surface. In this way, the step bottom surface F21a may be parallel to the horizontal plane, and the step angle C may be an obtuse angle within the range that functions as the pin step portion F21.

FIG. 5 is a side view showing a third modification of the rotary tool of the present invention. As shown in FIG. 5, in the rotary tool FC according to the third modification, the step bottom surface F21a is inclined upward by 10 degrees with respect to the horizontal plane toward the outer circumferential direction from the rotation axis of the tool. The stepped side surface F21b is parallel to the vertical plane. In this way, the step bottom surface F21a may be formed to be inclined upward from the horizontal plane toward the outer circumferential direction from the rotation axis of the tool within a range that can suppress the plastic flow material during friction stirring. The first to third modified examples of the rotary tool described above can also provide effects similar to those of the embodiment described below.

[First embodiment]
As shown in FIG. 6, in the joining method according to this embodiment, a metal main body 1 and a metal lid member 2 are joined by friction stir welding to form a hollow container.

The main body 1 is a box-shaped body that is open at the top. The main body 1 is composed of a bottom portion 10, a peripheral wall portion 11, and an inclined table 3. Although the main body 1 is made of an aluminum alloy in this embodiment, it can be appropriately selected from metals that can be friction stirred. For example, the main body 1 can be formed of aluminum alloy, magnesium alloy, copper alloy, aluminum, magnesium, titanium, or the like.

The bottom portion 10 has a rectangular plate shape in plan view. The peripheral wall portion 11 is erected on the periphery of the bottom portion 10 and has a rectangular frame shape in plan view. The peripheral wall portion 11 is composed of wall portions 11A, 11B, 11C, and 11D having the same thickness. The wall portions 11A and 11C are short side portions and are opposed to each other. The wall portions 11B and 11D have long sides and face each other. A recess 12 is formed inside the bottom portion 10 and the peripheral wall portion 11 .

A peripheral wall step portion 13 is formed on the end surface 11 a of the peripheral wall portion 11 along the inner peripheral edge of the peripheral wall portion 11 of the main body 1 . The peripheral wall step portion 13 includes a step bottom surface 13a and a step side surface 13b rising from the step bottom surface 13a. The stepped bottom surface 13a is formed at a position one step lower than the end surface 11a.

The inclined table 3 is provided on the end surface 11a. The slope 3 includes a slope side 3a, a slope side 3b, a slope 3c, and a back surface 3d. The slope side surface 3a and the slope side surface 3b are side surfaces of the slope table 3, and are opposed to each other. The inclined table 3 is arranged so that the inclined direction of the inclined surface 3c faces the recess 12. Further, the lower end of the inclined surface 3c is parallel to the inner peripheral edge of the peripheral wall portion 11. The back surface 3d rises perpendicularly from the end surface 11a and is perpendicular to the slope side surface 3a and the slope side surface 3b. The lower end of the inclined surface 3c and the stepped side surface 13b may be brought into contact with each other, but may be separated so as not to come into contact with the rotary tool F during the main joining process (see FIG. 6).

The slope 3c may be a slope that gradually rises, and may be a flat surface or a curved surface. In this embodiment, the inclined table 3 is provided on the end surface 11a of the wall portion 11D, but it may be provided on the end surface 11a of the wall portions 11A, 11B, and 11C. The inclined table 3 has a thickness (such that when the rotating tool F is raised along the inclined surface 3c and moved to the end position Ep, which will be described later), no pull-out holes and pull-out marks are left on the main body 1 by the rotating tool F ( height). That is, the slope 3 has a shape that increases in thickness from the lower end to the upper end of the slope 3c, and has a portion that is thicker than at least the depth at which the tip end pin F3 is inserted into the slope 3. is preferred.

The main body 1 is preferably formed by die casting, for example. By die casting, the main body 1 provided with the inclined table 3 can be easily formed integrally.

The lid member 2 is a plate member that is rectangular in plan view and seals the opening of the main body 1 . The material of the lid member 2 may be the same metal as the main body 1, or may be a different metal. Further, the material of the lid member 2 may be the same type of metal as the main body 1, and the hardness thereof may be changed. The lid member 2 is formed in a size that allows it to be placed on the peripheral wall stepped portion 13 with almost no gap. The plate thickness dimension of the lid member 2 may be larger than the height dimension of the stepped side surface 13b.

Next, a joining method according to this embodiment will be explained. The bonding method according to this embodiment includes a preparation process, a mounting process, a main bonding process, and a slope removal process.

The preparation process is a process of forming a main body 1 having a tilting table 3 and a recess 12, and a lid member 2 to be placed on the main body 1, as shown in FIG. The main body 1 is formed by die casting, for example.

The placing step is a step of placing the lid member 2 on the peripheral wall stepped portion 13 formed on the main body 1, as shown in FIG. The stepped side surface 13b of the peripheral wall stepped portion 13 and the side surface 2c of the lid member 2 are butted against each other to form a first abutting portion J1. Further, the stepped bottom surface 13a of the peripheral wall stepped portion 13 and the bottom surface 2b of the lid member 2 are butted against each other to form a second abutting portion J2. The end surface 11a of the peripheral wall portion 11 and the surface 2a of the lid member 2 are flush with each other.

The main joining process is a process of friction stir welding the main body 1 and the lid member 2, as shown in FIG. The main joining process in this embodiment includes a main process from the start position Sp to the intermediate point S1, and a separation process from the intermediate point S1 to the end position Ep. In this step, friction stir welding is performed using a rotating tool F along the first abutting portion J1. The rotary tool F is inserted into an arbitrarily set starting position Sp, and the rotary tool F is moved clockwise along the first butt portion J1.

As shown in FIG. 9, the insertion depth of the distal pin F3 is set so that the distal end of the distal pin F3 reaches the step bottom surface 13a of the peripheral wall stepped portion 13, and the outer circumferential surface of the proximal pin F2 is It is set so as to contact the end surface 11a of the peripheral wall portion 11 and the surface 2a of the lid member 2. Then, the rotary tool F is moved to trace the first abutting portion J1 while maintaining a constant height position.

A plasticized region W is formed on the movement locus of the rotary tool F. When the rotary tool F that started from the starting position Sp makes one revolution and reaches the starting position Sp, the plasticizing regions W are overlapped and moved to the intermediate point S1. When the rotary tool F reaches the intermediate point S1, the rotary tool F is not detached and moves directly to the detachment step.

The detachment step is a step of moving the rotary tool F from the intermediate point S1 to the end position Ep and detaching it on the inclined table 3, as shown in FIG. In the detachment process, the rotating tool F is moved to the inclined surface 3c of the inclined table 3 while keeping the insertion depth constant. Thereafter, the rotary tool F is moved along the inclined surface 3c while gradually separating from the end surface 11a. When the rotary tool F reaches the end position Ep, the rotary tool F is raised and removed from the inclined table 3.

As shown in FIG. 11, since the rotary tool F is raised along the inclined surface 3c, when the rotary tool F is moved to the end position Ep, the tip side pin F3 and the end surface 11a can be separated. Thereby, the pull-out hole created when the rotary tool F is removed does not remain in the main body 1, but can remain only in the inclined table 3.

The slope removal process is a process of removing the slope 3 from the main body 1. In the slope removal step, the slope 3 is completely removed using the end face 11a as a reference, for example, by cutting or grinding.

According to the joining method according to the present embodiment described above, the end position Ep of the rotary tool F is set on the inclined table 3, and the inclined table 3 is cut off. Thereby, it is possible to prevent a pull-out hole and a pull-out trace from remaining in the main body 1. Furthermore, since no pull-out holes or pull-out marks remain on the surface of the main body 1, a clean finish can be achieved.

In addition, in the present embodiment, in the main joining process, the outer circumferential surface of the proximal pin F2 is brought into contact with the end surface 11a of the peripheral wall portion 11 and the surface 2a of the lid member 2, as shown in FIG. However, since friction stirring is performed, the occurrence of burrs can be suppressed. In addition, since the plastic flow material can be held down by the outer circumferential surface of the proximal pin F2, the stepped groove formed on the joining surfaces (the end surface 11a of the main body 1 and the surface 2a of the lid member 2) can be made smaller. At the same time, the bulge formed on the sides of the stepped groove can be eliminated or made smaller.

Furthermore, since the step-like pin step portion F21 of the proximal pin F2 is shallow and has a wide outlet, the plastic fluid material can easily escape to the outside of the pin step portion F21 while being held down by the step bottom surface F21a. There is. Therefore, even if the plastic flow material is held down by the base pin F2, the plastic flow material is difficult to adhere to the outer circumferential surface of the base pin F2. Therefore, it is possible to reduce the bonding surface roughness and to suitably stabilize the bonding quality.

[Second embodiment]
Next, a joining method according to a second embodiment of the present invention will be described. This embodiment differs from the first embodiment in that a tilt table is formed on the lid member 2. In this embodiment, parts that are different from the first embodiment will be explained.

As shown in FIG. 12, in this embodiment, an inclined table 3B is formed to protrude above the surface 2a of the lid member 2. The slope 3 includes a slope side 3a, a slope side 3b, and a slope 3c. The slope side surface 3a and the slope side surface 3b are side surfaces of the slope table 3, and are opposed to each other. The inclined direction of the inclined surface 3c is perpendicular to the first abutting portion J1. The lower end of the inclined surface 3c and the side surface 2c may be separated from each other so as not to come into contact with the rotary tool F during the main joining process.

The inclined base 3B of the lid member 2 can be formed by die-casting, for example, similarly to the first embodiment. Thereby, the inclined table 3B and the lid member 2 can be easily formed integrally.

This joining process is the same as that of the first embodiment except that it is separated on the inclined table 3B. Further, since the other steps are the same as those in the first embodiment, detailed explanations will be omitted. In this way, even with the joining method according to the second embodiment, substantially the same effects as those of the first embodiment can be achieved.

[Third embodiment]
Next, a joining method according to a third embodiment of the present invention will be described. This embodiment is different from the second embodiment in the direction in which the slope is formed. In this embodiment, parts that are different from the second embodiment will be explained.

In this embodiment, as shown in FIG. 13, the tilting direction of the tilting table 3C is formed parallel to the first abutting portion J1.

The tilt table 3C is provided on the lid member 2. The slope 3C includes a slope side 3a, a slope side 3b, a slope 3c, and an approach portion 3e. The slope side surface 3a and the slope side surface 3b are side surfaces of the slope table 3, and are opposed to each other. The slope side surface 3a is formed at a position spaced apart from the side surface 2c of the lid member 2. The distance from the side surface 3a of the slope table 2 to the side surface 2c of the lid member 2 is preferably set so that the rotary tool F and the slope table 3 do not interfere with each other when performing the main joining process.

The slope 3c may be a slope that gradually rises, and may be a flat surface or a curved surface. The approach portion 3e has a lower end in contact with the surface 2a of the lid member 2 and an upper end in contact with the inclined surface 3c, and is gently curved and inclined while changing its direction by 90 degrees. The lower end of the approach portion 3e and the side surface 2c of the lid member 2 may be separated from each other so as not to come into contact with the rotary tool F during the main joining process.

This joining process is the same as that of the first embodiment except that it is separated on the inclined table 3C. Further, since the other steps are the same as those in the first embodiment, detailed explanations will be omitted.

Even with the joining method described above, substantially the same effects as in the first embodiment can be achieved. Further, by providing the approach portion 3e on the inclined table 3, it is possible to smoothly move the rotary tool F from the first abutting portion J1 to the inclined table 3 without reducing the moving speed. Note that although the tilt table 3C of this embodiment is formed on the lid member 2, it may be formed on the end surface 11a of the main body 1 according to the first embodiment.

Although the present invention has been described above, the present invention is not limited to the embodiments and modified examples described above, and various changes can be made without departing from the spirit of the present invention.
In the above embodiment, the case where the inclined table 3 is integrally formed with the main body 1 is illustrated, but the main body 1 having the inclined table 3 can be prepared by attaching the inclined table to the main body 1 after forming the main body 1. You can. For example, the inclined table 3 can be provided in the main body 1 by arranging the separately formed inclined table 3 on the main body 1. At this time, it is preferable to temporarily attach the inclined table 3 placed on the main body 1 by welding. Similarly, when forming the slope 3 so as to protrude above the surface 2a of the lid member 2, the lid member 2 having the slope 3 is prepared by attaching the slope later after forming the lid member 2. Good too. At this time, it is preferable to temporarily attach the inclined table 3 placed on the lid member 2 by welding.

1 Main body 2 Lid member 3, 3B, 3C Inclined table 10 Bottom part 11 Peripheral wall part 11a End surface 11A Wall part 11B Wall part 11C Wall part 11D Wall part 12 Recessed part 13 Peripheral wall step part 13a Step bottom surface 13b Step side surface J1 First butt part J2 Second Two butt parts F Rotating tool F2 Proximal pin F3 Distal pin F4 Flat surface W Plasticized area

Claims (2)

A joining method for joining a main body having a recess and a lid member for sealing an opening of the recess by friction stirring, the method comprising:
A rotary tool used in friction stirring includes a proximal pin and a distal pin, the proximal pin has a taper angle larger than the distal pin, and the proximal pin has an outer circumferential surface. A step-like step is formed,
The main body has a bottom and a peripheral wall rising from a peripheral edge of the bottom, and an inner peripheral wall of the peripheral wall includes a stepped bottom surface that is one step lower than an end surface of the peripheral wall, and a stepped side surface that rises from the stepped bottom surface. an approach part whose lower end contacts the end surface of the peripheral wall and is gently curved and inclined while changing direction; and a slope which contacts the upper end of the approach part and gradually rises. a preparation step of preparing a main body having a slope and a slope close to the stepped side surface;
By placing the lid member on the main body, the stepped side surface of the peripheral wall stepped portion and the side surface of the lid member are abutted against each other to form a first abutting portion, and the stepped bottom surface of the peripheral wall stepped portion and the lid member are abutted against each other. a placing step of forming a second abutting portion by overlapping the back side of the
Insert the rotating distal end pin into the first abutment part, and move along the first abutment part with the outer circumferential surface of the proximal pin in contact with the end face of the peripheral wall part and the surface of the lid member. After moving the rotary tool to perform friction stirring, the rotary tool is moved to the approach section, and while being moved from the approach section to the inclined surface, the tip side pin is raised along the inclined surface. a main joining step of moving the pin in this manner and pulling out the tip end pin above the inclined surface;
A joining method comprising, after the main joining step, a slope removal step of removing the slope. A joining method for joining a main body having a recess and a lid member for sealing an opening of the recess by friction stirring, the method comprising:
A rotary tool used in friction stirring includes a proximal pin and a distal pin, the proximal pin has a taper angle larger than the distal pin, and the proximal pin has an outer circumferential surface. A step-like step is formed,
The main body has a bottom and a peripheral wall rising from a peripheral edge of the bottom, and an inner peripheral wall of the peripheral wall includes a stepped bottom surface that is one step lower than an end surface of the peripheral wall, and a stepped side surface that rises from the stepped bottom surface. an approach portion whose lower end contacts the surface of the lid member and is gently curved and inclined while changing direction; and an inclined surface that contacts the upper end of the approach portion and gradually rises. a preparation step of preparing a lid member having an inclined surface and a slope proximate to a side surface of the lid member;
By placing the lid member on the main body, the stepped side surface of the peripheral wall stepped portion and the side surface of the lid member are abutted against each other to form a first abutting portion, and the stepped bottom surface of the peripheral wall stepped portion and the lid member are abutted against each other. a placing step of forming a second abutting portion by overlapping the back side of the
Insert the rotating distal end pin into the first abutting part, and move along the first abutting part with the outer circumferential surface of the proximal pin in contact with the end face of the peripheral wall part and the surface of the lid member. After moving the rotary tool to perform friction stirring, the rotary tool is moved to the approach section, and while being moved from the approach section to the inclined surface, the tip side pin is raised along the inclined surface. a main joining step of moving the pin in this manner and pulling out the tip end pin above the inclined surface;
A joining method comprising, after the main joining step, a slope removal step of removing the slope.

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