JP2009039772A - Joining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joining method in which friction stirring is performed in a butted part between metallic members from their surface side and rear side and in which airtightness and watertightness can be improved between both sides of the metallic members. <P>SOLUTION: This is a joining method in which friction stirring is performed for a metallic members 1 to be joined by butting a first and a second metallic member 1a, 1b. The method includes: a first normal welding stage in which friction stirring is performed on the surface A of the metallic members 1 to be joined at the butted part J1 between the first and the second metallic member 1a, 1b; a second normal welding stage in which friction stirring is performed on the rear side B of the metallic members 1 to be joined at the butted part J1; and a welding joining stage in which welding is performed on the side of the metallic members 1 to be joined at the butted part J1. The welding joining stage is characterized in that an unplasticized region is hermetically sealed by covering with a weld metal T, a region between the surface side plasticized region W1 formed in the first normal welding stage and the rear side plasticized region W2 formed in the second normal welding stage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for joining metal members using friction stirring.

  Friction stir welding (FSW = Friction Stir Welding) is known as a method for joining metal members. Friction stir welding is a process of rotating a rotating tool along the abutting portion between metal members, and plastically flowing the metal at the abutting portion by frictional heat between the rotating tool and the metal member. It is what is joined. In general, the rotating tool is formed by protruding a stirring pin (probe) on the lower end surface of a shoulder portion having a cylindrical shape.

14 and 15 are perspective views showing a conventional joining method in which friction stir welding is performed on a pair of metal members. As shown in FIG. 14, when the thickness of the metal members 101, 101 to be joined is larger than the length of the stirring pin of the rotating tool (not shown), after performing the friction stir welding from the surface 102 side of the metal member 101. In some cases, friction stir welding is also performed from the back surface 103 side.
That is, the conventional joining method 100 performs friction stir welding from both sides of the front surface 102 and the back surface 103 along the abutting portion 104 (two-dot chain line) of the metal members 101, 101, and is a plasticized region formed by friction stir welding. It joins so that the center part of the thickness direction of 105,106 may contact. Thereby, in the butt | matching part 104, it can join without a clearance gap.

Japanese Patent Laying-Open No. 2005-131666 (see FIG. 7)

  However, as shown in FIG. 15, when the thickness of the metal members 111 and 111 to be joined is large, even if friction stir welding is performed from the front surface 102 and the back surface 103, the center portion of the abutting portion 104 (two-dot chain line) is not yet present. There is a possibility that a plasticized region will occur. That is, when the thickness of the metal member 111 is very large with respect to the length of the stirring pin of the rotating tool (not shown), even if friction stirring is performed from the front surface 102 and the back surface 103 of the metal member 111, the plasticizing region 105 is obtained. , 106 cannot be brought into contact with the central portion in the thickness direction, and a gap (unplasticized region 119) is generated in the central portion of the abutting portion 104. Thus, when the unplasticized area | region 119 which continues from the one side surface 107 to the other side surface 108 arises, there existed a problem that the watertightness and airtightness between the side surface 107 and the side surface 108 fell.

  Here, if the length of the stirring pin of the rotary tool is increased according to the thickness of the metal member 111, the metal members 111 can be joined together without gaps by performing friction stir welding from the front surface 102 and the back surface 103. is there. However, since the rotating tool moves while the stirring pin is buried in the metal member 111 and rotates at a high speed, if the length of the stirring pin is increased, the load acting on the driving means of the friction stirrer and the stirring pin increases. However, there is a problem that the life of the apparatus is shortened.

  Further, as shown in FIGS. 14 and 15, in the plasticized regions 105 and 106, there may be a cavity defect 109 that continues from one side surface 107 to the other side surface 108. The cavity defect 109 contributes to a decrease in watertightness and airtightness between the side surface 107 and the side surface 108 of the metal members 101 and 111.

  From this point of view, the present invention can perform the friction stir welding of the abutting portions between the metal members from the front side and the back side of the metal member and improve the air tightness and water tightness between the both side surfaces of the metal member. It is an object to provide a simple joining method.

  A joining method according to the present invention that solves such a problem is a joining method in which a rotating tool is moved with respect to a metal member to be joined formed by abutting a first metal member and a second metal member to perform friction stirring. A first main joining step in which friction stir is performed on the surface of the metal member to be joined to the abutting portion between the first metal member and the second metal member, and the metal to be joined to the abutting portion. A second main joining step in which friction agitation is performed on the back surface of the member, and a welding joining step in which welding is performed on a side surface of the metal member to be joined with respect to the abutting portion. An unplasticized region between the front side plasticized region formed in the main joining step and the back side plasticized region formed in the second main joining step is covered with a weld metal and sealed. And

  According to such a joining method, the front surface and the back surface are frictionally stirred, and the abutting portions on the side surfaces are welded to cover the unplasticized region existing between the front surface side plasticized region and the back surface side plasticized region with the weld metal. Therefore, airtightness and watertightness between both side surfaces of the metal member to be joined can be improved.

  Further, the present invention includes a concave groove forming step of forming a concave groove along the abutting portion of the side surface of the metal member to be joined before the welding joint step, and in the welding joint step, It is preferable to fill the groove with the weld metal.

According to such a joining method, by filling the concave groove with the weld metal, the unplasticized region can be more reliably sealed and the strength of the joined portion can be increased.
Here, if friction stir welding is performed on the abutting portion in the first main joining step and the second main joining step, the filling metal for filling the gap of the abutting portion is insufficient due to the occurrence of burrs. There is a possibility that a tunnel-like cavity defect (hereinafter referred to as a tunnel-like cavity defect) that is continuous between both side surfaces is formed inside the region and the back surface side plasticized region. Further, when the friction stir welding in the first main joining step and the second main joining step is applied to the side surface of the metal member to be joined, the oxide film formed on the side surface is changed to the surface side plasticizing region and the back side plasticity. There is a possibility of being caught inside the conversion area.
However, according to the joining method according to the present invention, a concave groove is formed on the side surface even if a tunnel-like cavity defect or an oxide film is generated inside the front side plasticization region and the back side plasticization region. Thus, the oxide film can be removed, and the tunnel-like cavity defect can be divided by filling the groove with the weld metal. Thereby, the watertightness and airtightness between both side surfaces can be improved more.

  Moreover, it is preferable that the width | variety of the said ditch | groove is smaller than the width | variety of the said surface side plasticization area | region and the said back surface side plasticization area | region. According to such a joining method, since the range in which the weld metal is filled can be reduced, work efficiency can be improved.

  Moreover, it is preferable that this invention excises the part which protruded from the side surface of the to-be-joined metal member among the said weld metals after the said welding joining process. According to this joining method, the finished surface can be formed smoothly by cutting away the weld metal protruding from the side surface. In addition, the part which protruded from the side surface of the to-be-joined metal member among weld metals is also hereafter called a build-up part.

  In the present invention, a pilot hole may be formed in advance at a position where the rotary tool is to be inserted. According to such a joining method, it is possible to reduce press-fit resistance when the rotary tool is pushed in. Thereby, while improving the precision of friction stir welding, a joining operation can be performed rapidly.

  According to the joining method according to the present invention, the abutting portions between the metal members can be frictionally stirred from the front surface side and the back surface side of the metal members, and the air tightness and water tightness between both side surfaces of the metal members can be improved.

[First embodiment]
In the joining method according to the present invention, as shown in FIG. 1A, the front surface A and the back surface B of the metal member 1 to be joined formed by abutting the first metal member 1a and the second metal member 1b are joined by friction stirring. In addition, with respect to both side surfaces of the metal member 1 to be joined, as shown in FIG. 1B, after forming the concave groove K, overlay welding is performed on the concave groove K. .
First, the metal member 1 to be bonded of the bonding method according to the present embodiment will be described in detail, and the first tab material 2 and the second tab material 3 used when bonding the metal member 1 to be bonded will be described in detail. To do.

As shown in FIGS. 2A and 2B, the metal member 1 to be joined includes a first metal member 1a and a second metal member 1b that are rectangular in cross-section, and each end face is abutted. Thus, the abutting portion J1 is formed. In the present embodiment, the first metal member 1a and the second metal member 1b are metal materials having the same composition, for example, friction such as aluminum, aluminum alloy, copper, copper alloy, titanium, titanium alloy, magnesium, and magnesium alloy. It consists of a stirrable metal material. Although there is no restriction | limiting in particular in the shape and dimension of the 1st metal member 1a and the 2nd metal member 1b, It is desirable to make the thickness dimension in the abutting part J1 the same at least.
In addition, as shown in FIG. 1, let the surface of the to-be-joined metal member 1 be the surface A, the back surface is the back surface B, one side surface is the 1st side surface C, and the other side surface is the 2nd side surface D. Also, the vertical and horizontal directions in the present embodiment follow the arrows in FIG.

  As shown in FIGS. 2A and 2B, the first tab member 2 and the second tab member 3 are arranged so as to sandwich the butted portion J1 of the metal member 1 to be joined, The seam (boundary line) between the first metal member 1a and the second metal member 1b, which is attached to the bonded metal member 1 and appears on the first side surface C and the second side surface D, is obscured. Although there is no restriction | limiting in particular in the material of the 1st tab material 2 and the 2nd tab material 3, In this embodiment, it forms with the metal material of the same composition as the to-be-joined metal member 1. FIG. Moreover, there is no restriction | limiting in particular also in the shape and dimension of the 1st tab material 2 and the 2nd tab material 3, In this embodiment, the thickness dimension is the same as the thickness dimension of the to-be-joined metal member 1 in the butt | matching part J1. I have to.

  Next, referring to FIG. 4, a rotary tool F used in the temporary joining process (hereinafter referred to as “temporary joining rotary tool F”) and a rotary tool G used in the main joining process (hereinafter referred to as “main joining rotary tool”). G ”) will be described in detail.

  The temporary joining rotary tool F shown in FIG. 4A is made of a metal material harder than the metal member 1 to be joined, such as tool steel, and has a cylindrical shoulder portion F1 and a lower end face F11 of the shoulder portion F1. And an agitating pin (probe) F2 provided in a protruding manner. The size and shape of the temporary bonding rotary tool F may be set according to the material and thickness of the metal member 1 to be bonded, but at least the main bonding rotating tool G used in the first main bonding step described later. (Refer to FIG. 4B). This makes it possible to perform temporary bonding with a load smaller than that of the main bonding, so that it is possible to reduce the load applied to the friction stirrer at the time of temporary bonding. Since the moving speed (feeding speed) can be made faster than the moving speed of the main joining rotary tool G, the working time and cost required for temporary joining can be reduced.

The lower end surface F11 of the shoulder portion F1 is a portion that plays a role of pressing the plastic fluidized metal and preventing scattering to the surroundings, and is formed in a concave shape in this embodiment. There is no particular limitation on the size of the outer diameter X ₁ of the shoulder portion F1, in this embodiment, is smaller than the outer diameter Y ₁ of the shoulder portion G1 of the joining rotation tool G.

The stirring pin F2 hangs down from the center of the lower end surface F11 of the shoulder portion F1, and is formed into a tapered truncated cone shape in this embodiment. In addition, a stirring blade engraved in a spiral shape is formed on the peripheral surface of the stirring pin F2. There is no particular limitation on the size of the outer diameter of the stirring pin F2, in the present embodiment, the maximum outer diameter of the stirring pin G2 of the maximum outer diameter (upper diameter) X ₂ is rotated for the welding tool G (upper end diameter) Y ₂ smaller than, and the minimum outer diameter (bottom diameter) _{X 3} is smaller than the minimum outer diameter (bottom diameter) _{Y 3} of the stirring pin G2. The length L ₂ of the stirring pin F2 is preferably smaller than the stirring pin G2 of the joining rotation tool G length L _{1 (see} FIG. 4 (b)).

  A main rotating tool G for joining shown in FIG. 4B is made of a metal material harder than the metal member 1 to be joined, such as tool steel, and has a cylindrical shoulder portion G1 and a lower end face G11 of the shoulder portion G1. And an agitating pin (probe) G2 provided in a protruding manner.

  The lower end surface G11 of the shoulder portion G1 is formed in a concave shape like the temporary joining rotary tool F. The stirring pin G2 hangs down from the center of the lower end surface G11 of the shoulder portion G1, and is formed into a tapered truncated cone shape in this embodiment. In addition, a stirring blade engraved in a spiral shape is formed on the peripheral surface of the stirring pin G2.

Hereinafter, the joining method according to the present embodiment will be described in detail. The bonding method according to this embodiment includes (1) a first preparation step, (2) a first preliminary step, (3) a first main bonding step, (4) a second preparation step, and (5) a first. It includes two preliminary steps, (6) a second main joining step, (7) a tab material cutting step, (8) a groove forming step, (9) a welding joining step, and (10) a built-up portion cutting step.
In addition, as shown in FIG. 1, (2) 1st preliminary process and (3) 1st this joining process are processes performed in the surface A, (5) 2nd preliminary process and (6 ) The second main joining process is a process executed on the back surface B. In addition, (8) the groove forming step, (9) the welding joining step, and (10) the build-up portion cutting step are steps that are executed on both the first side surface C and the second side surface D.

(1) First Preparation Step The first preparation step will be described with reference to FIGS. A 1st preparation process is a process of preparing the contact member (the 1st tab material 2 and the 2nd tab material 3) in which the start position and completion | finish position of the friction stirring of the to-be-joined metal member 1 are provided. In the present embodiment, the first preparation step includes a butting step of butting the first metal member 1a and the second metal member 1b, and the first tab material 2 and the second on both sides of the butting portion J1 of the metal member 1 to be joined. A tab material arranging step of arranging the tab material 3, and a temporary welding step of temporarily joining the first tab material 2 and the second tab material 3 to the metal member 1 to be joined by welding.

(1-1) Butting Step In the matching step, as shown in FIG. 2B, the end surface 11b of the second metal member 1b is brought into close contact with the end surface 11a of the first metal member 1a. Moreover, as shown in FIG. 3 etc., the surface 12a of the first metal member 1a and the surface 12b of the second metal member 1b are flush with each other, and further, the back surface 13a of the first metal member 1a and the back surface of the second metal member 1b. 13b is flush. Similarly, the first side surface 14a of the first metal member 1a and the first side surface 14b of the second metal member 1b are flush with each other, and the second side surface 15a of the first metal member 1a and the second side of the second metal member 1b. The side surface 15b is flush.

  That is, the surface A is formed by the surface 12a of the first metal member 1a and the surface 12b of the second metal member 1b, and the back surface B is formed by the back surface 13a of the first metal member 1a and the back surface 13b of the second metal member 1b. The first side surface C is formed by the first side surface 14a of the first metal member 1a and the first side surface 14b of the second metal member 1b, and the second side surface D is the second side surface 15a of the first metal member 1a. It is formed by the second side surface 15b of the second metal member 1b.

(1-2) Tab Material Arrangement Step In the tab material arrangement step, as shown in FIG. 2B, the first tab material 2 is arranged on the first side C side of the abutting portion J1, and the contact surface thereof. 21 is brought into contact with the first side face C. Furthermore, the 2nd tab material 3 is arrange | positioned in the 2nd side surface D of the abutting part J1, and the contact surface 31 is made to contact | abut to the 2nd side surface D. FIG. At this time, as shown in FIG. 3B, the surface 22 of the first tab member 2 and the surface 32 of the second tab member 3 are flush with the surface A of the metal member 1 to be joined, and the first tab. The back surface 23 of the material 2 and the back surface 33 of the second tab material 3 are flush with the back surface B of the bonded metal member 1.

(1-3) Temporary Joining Process In the temporary welding process, as shown in FIGS. 2A and 2B, corners 2a and 2b formed by the metal member 1 to be joined and the first tab material 2 are used. Are welded to temporarily join the metal member 1 and the first tab member 2 together. Furthermore, the corners 3 a and 3 b formed by the metal member 1 and the second tab material 3 are welded to temporarily bond the metal member 1 and the second tab material 3 to each other.
In addition, welding may be performed continuously over the entire length of the corners 2a, 2b and 3a, 3b, or welding may be performed intermittently. Further, in the first preparation step, when the temporary welding step is omitted, the abutting step and the tab material arranging step may be performed on a frame of a friction stirrer (not shown).

(2) First Preliminary Step The first preliminary step is a step performed prior to the first main joining step, and in the present embodiment, on the surface A side, the metal member 1 and the second tab member to be joined. (2-1) the second tab material joining step, which joins the butting portion J3 with the joint 3, and the joining portion J1 of the joined metal member 1 are temporarily joined (2-2) the temporary joining step, and the joined metal member 1 (2-3) A pilot hole is formed at the friction stir start position in the first tab material joining step and the first main joining step (2-4). A pilot hole forming step.

In the first preliminary process, as shown in FIG. 6, one temporary joining rotary tool F is moved so as to form a one-stroke writing movement trajectory (bead), with respect to the abutting portions J3, J1, and J2. Continuous friction stir. That is, the stirring pin F2 (see FIG. 4A) of the temporary joining rotary tool F inserted at the friction stirring start position _SP1 is moved to the end position _EP1 without being removed halfway. In this embodiment, the second tab member 3 is provided with the friction stirring start position S _P1 and the first tab member 2 is provided with the end position E _P1 . However, the positions of the start position S _P1 and the end position E _P1 are the same. It is not intended to limit. In the present embodiment, the rotation directions of the temporary welding rotary tool F and the main welding rotary tool G are all rotated clockwise. In this way, by unifying the rotation directions of the temporary joining rotary tool F and the main joining rotary tool G, it is possible to save labor.

The procedure of friction stirring in the first preliminary process of this embodiment will be described in more detail with reference to FIGS.
First, the metal member 1 to be joined that has undergone the temporary welding process is fixed to a frame of a friction stirrer (not shown). Then, as shown in (a) of FIG. 5, positions the rotary tool F for temporary bonding directly on the start position S _P1 provided in place of the second tab member 3, followed by the rotary tool F for temporary joining It is lowered while rotated clockwise presses the start position S _P1 stirring pin F2 with. The rotational speed of the rotary tool F for temporary joining is set according to the size and shape of the stirring pin F2, the material and thickness of the joined metal member 1 to be frictionally stirred, etc. It is set within a range of 500 to 2000 (rpm).

  When the stirring pin F2 comes into contact with the surface 32 of the second tab member 3, the metal around the stirring pin F2 is plastically fluidized by frictional heat, and the stirring pin F2 is moved to the second tab as shown in FIG. Inserted into the material 3.

  When the entire stirring pin F2 enters the second tab member 3 and the entire lower end surface F11 of the shoulder portion F1 contacts the surface 32 of the second tab member 3, as shown in FIG. While rotating F, it is relatively moved toward the starting point s3 of the second tab material joining step.

  The moving speed (feeding speed) of the temporary bonding rotary tool F is set according to the size and shape of the stirring pin F2, the material and thickness of the metal member 1 to be bonded and the like to be frictionally stirred, In many cases, it is set within a range of 100 to 1000 (mm / min). The rotational speed at the time of movement of the temporary joining rotary tool F is the same as or lower than the rotational speed at the time of insertion. Note that when the temporary welding rotary tool F is moved, the axis of the shoulder portion F1 may be slightly inclined to the rear side in the traveling direction with respect to the vertical line. The direction of the joining rotary tool F can be easily changed, and complicated movement is possible. When the rotary tool F for temporary joining is moved, the metal around the stirring pin F2 is plastically fluidized sequentially, and the metal that has been plastically fluidized is hardened again at a position away from the stirring pin F2.

  When the frictional stirring is continuously performed up to the starting point s3 of the second tab material joining process by relatively moving the temporary tool F for the temporary joining, the second tab material joining is performed without removing the temporary joining rotary tool F at the starting point s3. Move to the process.

(2-1) Second Tab Material Joining Step In the second tab material joining step, friction agitation is performed on the abutting portion J3 between the second tab material 3 and the metal member 1 to be joined. Specifically, by setting a friction stir route on the joint (boundary line) between the metal member 1 to be joined and the second tab member 3, and relatively moving the rotary tool F for temporary joining along the route, Friction stirring is performed on the abutting portion J3. In the present embodiment, the friction stir is continuously performed from the start point s3 to the end point e3 of the second tab material joining step without causing the temporary joining rotary tool F to be detached on the way.

  In addition, when the rotary tool F for temporary joining is rotated to the right, there is a possibility that a fine cavity defect may be generated on the left side of the traveling direction of the temporary tool F for temporary joining. It is desirable to set the positions of the start point s3 and the end point e3 of the second tab member joining step so that the metal member 1 to be joined is located on the right side of the first tab member. If it does in this way, since it becomes difficult to generate | occur | produce a cavity defect in the to-be-joined metal member 1 side, it becomes possible to obtain a high quality joined body.

  Incidentally, when the temporary bonding rotary tool F is rotated counterclockwise, a fine cavity defect may occur on the right side of the moving direction of the temporary bonding rotary tool F. It is desirable to set the positions of the start point and end point of the second tab material joining step so that the metal member 1 to be joined is located on the left side of the first tab member. Specifically, although illustration is omitted, a starting point is provided at the position of the end point e3 when the temporary joining rotary tool F is rotated to the right, and the position of the starting point s3 when the temporary joining rotary tool F is rotated to the right. An end point may be provided at.

  When the stirring pin F2 of the temporary joining rotary tool F enters the abutting portion J3, a force acts to separate the metal member 1 to be bonded and the second tab member 3 from each other. Since the corners 3a and 3b (see FIG. 2) formed by the material 3 are temporarily joined by welding, no openings are generated between the metal member 1 to be joined and the second tab material 3. .

(2-2) Temporary joining step When the temporary tool F for temporary joining reaches the end point e3 of the second tab material joining step, the friction stir is continuously performed to the start point s1 of the temporary joining step without terminating the friction stirring at the end point e3. And proceed to the temporary joining process as it is. That is, the frictional stirring is continued without detaching the temporary joining rotary tool F from the end point e3 of the second tab material joining process to the starting point s1 of the temporary joining process, and further, the temporary joining rotary tool F is detached at the start point s1. It moves to a temporary joining process without it. If it does in this way, the separation work of temporary rotating tool F for temporary joining in the end point e3 of the 2nd tab material joining process becomes unnecessary, and also the insertion work of rotating tool F for temporary joining in the starting point s1 of a temporary joining process is unnecessary. Therefore, it becomes possible to improve the efficiency and speed of the preliminary joining work.

  In the present embodiment, the friction stir route from the end point e3 of the second tab material joining process to the start point s1 of the temporary joining process is set to the second tab material 3, and the temporary joining rotary tool F is set to the second tab material joining process. The movement trajectory when moving from the end point e3 to the start point s1 of the temporary joining step is formed on the second tab member 3. If it does in this way, since it becomes difficult to generate | occur | produce a cavity defect in the to-be-joined metal member 1 in the process from the end point e3 of a 2nd tab material joining process to the start point s1 of a temporary joining process, obtaining a high quality joined body. Is possible.

  In the temporary joining step, friction agitation is performed on the abutting portion J1 (see FIG. 6) of the metal member 1 to be joined. Specifically, a route for friction stirring is set on the joint (boundary line) of the metal member 1 to be joined, and the temporary tool rotation tool F is relatively moved along the route so that the total length of the abutting portion J1 is obtained. Friction stirring is continuously performed throughout. In the present embodiment, the friction stir is continuously performed from the start point s1 to the end point e1 of the temporary joining step without causing the temporary joining rotary tool F to be detached.

  When the temporary joining rotary tool F reaches the end point e1 of the temporary joining step, the friction stirrer is continuously performed up to the start point s2 of the first tab member joining step without terminating the friction stirrer at the end point e1, and the first tab member is directly processed. Transition to the joining process. That is, the frictional stirring is continued without detaching the temporary joining rotary tool F from the end point e1 of the temporary joining step to the start point s2 of the first tab material joining step, and further, the temporary joining rotary tool F is detached at the start point s2. It moves to the 1st tab material joining process, without.

  In this embodiment, the friction stir route from the end point e1 of the temporary joining step to the start point s2 of the first tab member joining step is set to the first tab member 2, and the temporary joining rotary tool F is set to the end point e1 of the temporary joining step. The first tab member 2 is formed with a movement locus when moving from the first tab member joining step to the starting point s2. If it does in this way, since a cavity defect becomes difficult to generate | occur | produce in the to-be-joined metal member 1 in the process from the end point e1 of a temporary joining process to the start point s2 of a 1st tab material joining process, obtaining a high quality joined body. Is possible.

(2-3) First Tab Material Joining Step In the first tab material joining step, friction agitation is performed on the abutting portion J2 between the metal member 1 to be joined and the first tab material 2. Specifically, by setting a friction stir route on the joint (boundary line) between the metal member 1 to be joined and the first tab member 2, and moving the rotary tool F for temporary joining relatively along the route, Friction stirring is performed on the abutting portion J2. In the present embodiment, the friction stir is continuously performed from the start point s2 to the end point e2 of the first tab material joining step without causing the temporary joining rotary tool F to be detached on the way.

  Since the temporary joining rotary tool F is rotated to the right, the start point s2 and the end point e2 of the first tab material joining step are set so that the metal member 1 to be joined is positioned on the right side in the traveling direction of the temporary joining rotary tool F. Set the position of.

  Moreover, when the stirring pin F2 of the rotary tool F for temporary joining enters the abutting portion J2, a force acts to separate the bonded metal member 1 and the first tab material 2 from each other, but the bonded metal member 1 and the first tab Since the corners 2 a and 2 b (see FIG. 2) of the material 2 are temporarily joined by welding, no openings are generated between the metal member 1 to be joined and the first tab material 2.

When the rotary tool F for temporary joining reaches the end point e2 of the first tab material joining step, the friction stir is continuously performed to the end position E _P1 provided in the first tab material 2 without terminating the friction stirring at the end point e2. Do. In the present embodiment, the end position E _P1 is provided on the extension line of the seam (boundary line) that appears on the surface A side of the bonded metal member 1. Incidentally, the end position E _P1 is also a friction stirring start position S _M1 in a first main joining process described later.

When the temporary joining rotary tool F reaches the end position E _P1 , the temporary joining rotary tool F is raised while rotating to disengage the stirring pin F2 from the end position E _P1 .

(2-4) Pilot hole forming step Subsequently, a pilot hole forming step is executed. As shown in FIG. 4B, the pilot hole forming step is a step of forming the pilot hole P1 at the friction stirring start position in the first main joining step. In the pilot hole forming process according to the first preliminary process, the pilot hole P1 is formed in S _M1 set on the surface 22 of the first tab member 2.

  The pilot hole P1 is provided for the purpose of reducing the insertion resistance (press-fit resistance) of the stirring pin G2 of the rotary tool G for main joining, and in this embodiment, the stirring pin F2 (see FIG. 4 (see (a)) is formed by expanding the diameter of the punched hole H1 formed with a drill (not shown). If the punch hole H1 is used, the process of forming the pilot hole P1 can be simplified, and the working time can be shortened. Although there is no restriction | limiting in particular in the form of the pilot hole P1, In this embodiment, it is cylindrical. In addition, in this embodiment, although the pilot hole P1 is formed in the 1st tab material 2, there is no restriction | limiting in particular in the position of the pilot hole P1, You may form in the 2nd tab material 3, and the butt | matching part J2 , J3 may be preferably formed on the extended line of the joint (boundary line) of the metal member 1 to be bonded that appears on the surface A side of the metal member 1 to be bonded as in the present embodiment. .

In this embodiment, the case where the diameter of the hole H1 of the stirring pin F2 (see FIG. 4A) of the temporary joining rotary tool F is enlarged to be the pilot hole P1 is illustrated. greater than the minimum outer diameter Y ₃ of the stirring pin G2 of the maximum outer diameter X ₂ is rotating tool G for the bonding, and smaller than the maximum outer diameter Y ₂ of the maximum outer diameter X ₂ of the stirring pin F2 agitation pin G2 In the case of (Y ₃ <X ₂ <Y ₂ ), the hole H1 of the stirring pin F2 may be used as the pilot hole P1 as it is.

(3) 1st main joining process A 1st main joining process is a process of joining the butt | matching part J1 in the surface A side of the to-be-joined metal member 1 in earnest. In the first main joining step according to the present embodiment, the surface of the metal member 1 to be joined is used with respect to the abutting part J1 in a temporarily joined state using the main joining rotating tool G shown in FIG. Friction stirring is performed from the A side.

In a first main bonding step, as shown in FIG. 7 (a) ~ (c), a stirring pin G2 of the joining rotation tool G inserted (press-fitted) into the prepared hole P1 formed in the start position S _M1 Then, the inserted stirring pin G2 is moved to the end position E _M1 without being removed halfway. That is, in the first main joining process, the friction stirring is started from the pilot hole P1, and the friction stirring is continuously performed up to the end position E _M1 .

Here, at the time when the first preliminary process is completed, the friction stirrer provided with the temporary joining rotary tool F is located immediately above the end position E _P1 of the first tab member 2 (see FIG. 6). Therefore, when the start position of the first main joining step is set to _SM1 , the first main joining step can be performed without moving the friction stirrer provided with the main welding rotating tool G. Can be omitted.
In the present embodiment, the first tab member 2 is provided with the friction stirring start position S _M1 and the second tab member 3 is provided with the end position E _M1 . However, the positions of the start position S _M1 and the end position E _M1 are the same. It is not intended to limit.

The first main joining process will be described in more detail with reference to FIGS.
First, as shown in FIG. 7A, the main welding rotary tool G is positioned immediately above the pilot hole P1 (start position S _M1 ), and then the main welding rotary tool G is rotated clockwise and lowered. The tip of the stirring pin G2 is inserted into the pilot hole P1. When the stirring pin G2 enters the pilot hole P1, the peripheral surface (side surface) of the stirring pin G2 comes into contact with the hole wall of the pilot hole P1, and the metal fluidizes plastically from the hole wall. In such a state, the agitation pin G2 is press-fitted while the plastic fluidized metal is pushed away by the peripheral surface of the agitation pin G2, so that the press-fitting resistance in the initial press-fitting stage can be reduced. In addition, since the stirring pin G2 contacts the hole wall of the pilot hole P1 and the frictional heat is generated before the shoulder portion G1 of the main rotating tool G contacts the surface 22 of the first tab member 2, plastic fluidization occurs. It is possible to shorten the time to do. That is, it is possible to reduce the load on the friction stirrer, and in addition, it is possible to shorten the work time required for the main joining.

  When the entire stirring pin G2 enters the first tab member 2 and the entire lower end surface G11 of the shoulder portion G1 comes into contact with the surface 22 of the first tab member 2, as shown in FIG. The main rotating tool G is relatively moved toward one end of the abutting portion J1 of the metal member 1 to be joined while stirring, and further, the abutting portion J2 is traversed to enter the abutting portion J1. When the rotary tool G for main joining is moved, the metal around the stirring pin G2 is plastically fluidized at the same time, and at the position away from the stirring pin G2, the plastic fluidized metal is hardened again and plasticized. A region (hereinafter referred to as “surface-side plasticized region W1”) is formed.

  The moving speed (feeding speed) of the main rotating tool G for welding is set according to the size and shape of the agitating pin G2, the material and thickness of the metal member 1 to be joined by friction stirring, In many cases, it is set within a range of 30 to 300 (mm / min).

  If the amount of heat input to the metal member 1 to be bonded is likely to be excessive, it is desirable to cool the surface of the main rotating tool G by supplying water from the surface A side. In addition, when cooling water enters between the first metal member 1a and the second metal member 1b, there is a possibility that an oxide film may be generated on the joining surfaces (end surfaces 11a and 11b, see FIG. 2B). In the embodiment, since the joint between the bonded metal members 1 is closed by executing the temporary bonding process, it is difficult for the cooling water to enter between the bonded metal members 1 and there is no possibility of deteriorating the quality of the bonded portion.

At the abutting portion J1 of the metal member 1 to be joined, a route of friction stirring is set on the joint of the metal member 1 to be joined (on the movement trajectory in the temporary joining process), and the main rotating tool G is relatively moved along the route. By moving, friction stir is performed continuously from one end to the other end of the abutting portion J1. After the main rotating tool G is relatively moved to the other end of the abutting portion J1, the abutting portion J3 is moved across the abutting portion J3 while performing frictional stirring, and is moved relative to the end position E _M1 as it is.

In the present embodiment, since the friction stirring start position S _M1 is set on the extension line of the joint (boundary line) of the metal member 1 to be bonded that appears on the surface A side of the metal member 1 to be bonded, The route of friction stirring in the main joining process can be made straight. If the route of friction stirring is made straight, the moving distance of the main welding rotary tool G can be minimized, so that the first main welding process can be efficiently performed. The wear amount of the tool G can be reduced.

When the main welding rotary tool G reaches the end position E _M1 , as shown in FIG. 7C, the main welding rotary tool G is raised while rotating and the stirring pin G <b> 2 is moved to the end position E _M1 (FIG. 7). (See (b)). Note that if the stirring pin G2 is separated upward at the end position E _M1 , a punch hole Q1 having substantially the same shape as the stirring pin G2 is inevitably formed, but in this embodiment, it is left as it is.

The rotational speed of the main welding rotary tool G when the stirring pin G2 of the main welding rotary tool G is detached from the end position _EM1 (the rotational speed at the time of separation) may be higher than the rotational speed at the time of movement. desirable. In this case, the separation resistance of the stirring pin G2 becomes smaller than when the rotational speed at the time of separation is the same as the rotational speed at the time of movement, so that the work of removing the stirring pin G2 at the end position E _M1 can be performed quickly. Can be done.

  In this embodiment, the first preliminary process is performed before the first main bonding process, but the first preliminary process is omitted and the first main process is performed immediately after the first preliminary process. A joining process may be performed.

(4) Second preparation step The second preparation step is a preparation step that is performed prior to the second preliminary step. In the present embodiment, a re-installation step is provided in which the back surface B side of the bonded metal member 1 is directed upward and is re-installed in a friction stirrer (not shown).

(4-1) Re-installation process In the re-installation process, after releasing the restraint of the bonded metal member 1 that has finished the first main bonding process, the reverse side of the bonded metal member 1 is reversed and the back surface B side is Place it on the base of the friction stirrer again, facing up. In this embodiment, the metal member 1 to be bonded is rotated halfway around the longitudinal axis shown in FIG. 1 so that the front and back of the metal member 1 to be bonded are reversed.
Here, FIG. 8A is a cross-sectional view facing the first metal member 1a side from the abutting portion J1 after the re-installation step of the second preparation step according to the present embodiment. As shown in FIG. 8A, in the re-installation process, when the upper surface of the metal member 1 to be bonded becomes the back surface B and the first metal member 1a is faced from the abutting portion J1 side, The first tab material 2 is located on the left side, and the second tab material 3 is located on the right side.
Note that, depending on the friction stirrer, the front and back surfaces may be rotated without releasing the restraint of the bonded metal member 1.
(5) Second Preliminary Step The second preliminary step is a step that is performed prior to the second main joining step, and on the back surface B side, the abutting portion J2 between the metal member 1 to be joined and the first tab member 2. (5-1) First tab material joining step, and temporarily joining the butted portion J1 of the metal member 1 to be joined (5-2) Temporary joining step, metal member 1 to be joined and second tab material 3 (5-3) a second tab material joining step, and a pilot hole is formed at a friction stirring start position in the second main joining step (5-4) a pilot hole forming step. It has. In the (5-1) first tab material joining step, (5-2) temporary joining step, and (5-3) second tab material joining step, the temporary joining rotary tool F is used.

(5-1) First tab material joining step, (5-2) Temporary joining step and (5-3) Second tab material joining step (5-1) First tab material joining step, (5-2) Temporary The joining step and the (5-3) second tab material joining step are (2-3) the first tab material joining step, (2-2) the temporary joining step and (2-1 ) The process is substantially equivalent to the second tab material joining process. As shown in FIG. 8 (b), one temporary joining rotary tool F is moved so as to form a one-stroke writing trajectory (bead), and the abutting portions J2, J1, J3 are successively arranged in this order. Friction stirring is performed. That is, the stirring pin F2 (see (a) of FIG. 4) of the temporary welding rotary tool F inserted at the friction stirring start position _SP2 is moved to the end position _EP2 without being removed halfway (5-1 The first tab material joining step, the (5-2) temporary joining step, and the (5-3) second tab material joining step are successively executed. Note that the end position E _P2 is a start position S _M2 of a second main joining process to be performed later.

Here, in the first preliminary step, as shown in FIG. 6, from the second tab member 3 side, (2-1) the second tab member joining step, (2-2) the temporary joining step, and (2-3 ) The first tab material joining step was sequentially performed. On the other hand, in the second preliminary step, when facing the first metal member 1a side from the abutting portion J1, the first tab member 2 is located on the left side of the metal member 1 to be joined and the first main joining step is finished. At this time, since the friction stirrer provided with the main rotating tool G for welding is located above the first tab member 2, from the first tab member 2 side, (5-1) the first tab member joining step ( 5-2) Temporary joining step and (5-3) Second tab material joining step are sequentially performed. In this case, since the moving distance of the friction stirrer provided with the temporary joining rotary tool F is small, work can be saved.
The detailed description of the (5-1) first tab material joining step, (5-2) temporary joining step, and (5-3) second tab material joining step is substantially the same as the first preliminary step. Omitted.

(5-4) prepared hole forming step the prepared hole forming step, as shown in FIG. 9 (a) is the step of forming a prepared hole P2 in the second start position S _M2 of the friction stir in the welding process . That is, the pilot hole forming step is a step of forming the pilot hole P2 at a position where the stirring pin G2 of the main rotating tool G is to be inserted. Thereby, the insertion resistance (press-fit resistance) of the stirring pin G2 of the rotating tool G for main joining can be reduced.
Since the (5-4) pilot hole forming step is substantially the same as the (2-4) pilot hole forming step according to the first preliminary process, detailed description thereof is omitted.

(6) Second Main Joining Step The second main joining step is a step of fully joining the abutting portion J1 on the back surface B side of the metal member 1 to be joined. In the second main joining step according to the present embodiment, the main joining rotating tool G is used, and friction agitation is performed from the back surface B side of the joined metal member 1 to the abutting portion J1 in a temporarily joined state.

In the second main joining step, as shown in FIGS. 9A and 9B, the stirring pin G2 of the main joining rotary tool G is inserted into _SM2 set on the back surface 33 of the second tab member 3. (Press-fitting), and the inserted stirring pin G2 is moved to the end position E _M2 without being removed halfway. In the second main joining step, friction agitation is started from the pilot hole P2, and friction agitation is continuously performed up to the end position _EM2 . When the rotary tool G for main joining is moved, the metal around the stirring pin G2 is plastically fluidized at the same time, and at the position away from the stirring pin G2, the plastic fluidized metal is hardened again and plasticized. A region (hereinafter referred to as “back side plasticizing region W2”) is formed.

Here, when the second preliminary process is completed, the friction stirrer provided with the temporary joining rotary tool F is located immediately above the end position E _P2 of the second tab member 3 (see FIG. 8A). Therefore, when the start position _SM2 of the second main joining process is set above the second tab member 3, the first book is moved without moving the friction stirrer equipped with the main joining rotating tool G. A joining process can be performed and a work can be omitted.
Note that the second main bonding step is substantially the same as the first main bonding step, and thus detailed description thereof is omitted. In the present embodiment, the second preliminary process is performed, but the second preliminary process may be omitted and the second main bonding process may be performed immediately after the first main bonding process.

(7) Tab Material Cutting Process The tab material cutting process is a process of cutting the first tab material 2 and the second tab material 3 from the bonded metal member 1. In this embodiment, the to-be-joined metal member 1 that has finished the second main joining step is once removed from the frame of the friction stirrer, and the first tab member 2 and the butt portion J2 and J3 are used along the abutting portions J2 and J3 using a cutting tool (not shown). The second tab member 3 is cut off.

  FIG. 10 is a perspective view showing the bonded metal member 1 after performing the tab material cutting step. As shown in FIG. 10, the front surface side plasticized region W1 and the back surface side plasticized region W2 are continuously formed from the first side surface C side to the second side surface D side. On the other hand, a fine unplasticized region j extending from the first side C side to the second side D side is formed between the front side plasticized region W1 and the back side plasticized region W2.

Here, in the front side plasticizing region W1 and the back side plasticizing region W2, the traveling direction of the main rotating tool G (see arrows V ₁ and V ₂ ) is on the left side, that is, the second metal member 1b It is assumed that tunnel-like cavity defects R ₁ and R ₂ are generated from the side C side to the second side D side. When the friction stir welding is performed, the tunnel-like cavity defects R ₁ and R ₂ are formed due to insufficient filling metal for filling the gap of the abutting portion J1 due to frequent occurrence of burrs.

Further, as shown in FIG. 10, both ends of the surface side plasticized region W1 and the rear surface side plasticized region W2, it is assumed that the oxide film S ₁ to S ₄ are involved. The oxide films S _{1 to} S ₄ are formed by winding the oxide film formed on the first side surface C or the second side surface D into the bonded metal member 1. For example, the oxide film S ₁ is, since the present joining rotation tool G is rotated clockwise, by involving the oxide film formed on the second side D into the interior of the second metal member 1b, the back surface side plasticized region It is easy to form on the second metal member 1b side related to W2.

(8) Concave Groove Forming Step The concavity groove forming step is a step of forming the concave groove K along the abutting portion J1 on the first side surface C and the second side surface D as shown in FIG. The concave groove K is a concave portion that is filled with a weld metal in a welding joining process described later. In this embodiment, the concave groove K is continuously formed from the back surface B to the front surface A with a constant width m and depth p using a known end mill or the like.

By providing the concave groove K, it is possible to suitably fill the weld metal and perform removal of the oxide films S _{1 to} S ₄ (see FIG. 10) when performing welding joining described later. That is, the width m and the depth p of the concave groove K may be appropriately set according to the size (range) of the oxide films S _{1 to} S ₄ . Moreover, it is preferable that the width m of the concave groove K and the width n of the back surface plasticizing region W2 are formed so that m <n. Thereby, since the range which fills a weld metal in the case of welding joining can be made small, working efficiency can be improved. In addition, in this embodiment, although the ditch | groove K was formed in the cross sectional view rectangle, it is not limited to this, Other shapes may be sufficient.

(9) Welding and joining process The welding and joining process is a process for performing welding and joining along the unplasticized region j according to the first side face C and the second side face D, as shown in FIG. In the present embodiment, it is preferable to perform overlay welding joining by TIG welding, MIG welding, or the like. The concave groove K can be filled with the weld metal T by overlay welding. Thus, the unplasticized region j existing between the front surface side plasticized region W1 and the back surface side plasticized region W2 can be reliably sealed with the weld metal T, and the strength of the joint portion can be increased.
Even if tunnel-like cavity defects R ₁ and R ₂ (see FIG. 10) continuous from the first side C to the second side D are formed, the tunnel K is filled with the weld metal T in the groove K. The hollow cavities R ₁ and R ₂ can be divided and encapsulated in the bonded metal member 1. In addition, although the welding material may differ from the to-be-joined metal member 1, in this embodiment, the same material is used.

(10) Build-up part excision process The build-up part excision process is performed from the surface of the first side face C or the second side face D in the weld metal T filled in the weld joining process, as shown in FIG. This is a step of cutting out the protruding portion (the built-up portion T ′). The surface of the 1st side C or the 2nd side D can be shape | molded smoothly by excising this build-up part T '.

  According to the joining method according to the present invention described above, as shown in FIG. 1, the front surface A and the back surface B side of the abutting portion J1 of the metal member 1 to be joined are joined by friction stirring, and the first side surface C And the second side face D is welded to cover and seal the unplasticized region j existing between the front surface side plasticized region W1 and the back surface side plasticized region W2 with the weld metal T. The airtightness and watertightness between both side surfaces can be improved.

Moreover, a tunnel-like void defects R ₁ communicating from a first side face C to the second _side, even if the R ₂ is formed, a tunnel-like void defects by filling the weld metal T into the groove K R _1, R ₂ Can be divided and encapsulated in the metal member 1 to be joined. Further, even if the oxide film on the surface side plasticized region W1 and the back side plasticized region W2 _S 1 ~S ₄ (see FIG. 10) is involved, the oxide film _S 1 to S at the time of forming the concave groove K ₄ can be excised. Thereby, the airtightness between both the side surfaces of the to-be-joined metal member 1 and watertightness can be improved more.

  Further, in the welding joining process, by performing overlay welding, the recessed groove K can be easily filled with the weld metal T, and the overlay portion T ′ protruding from the side surface of the weld metal T is excised. Thus, the finished surface can be smoothed.

[Second Embodiment]
In the first embodiment, the welding joining process is performed after forming the concave groove K, but the concave groove K may not be provided as in the second embodiment according to the present invention.
FIG. 13 is a diagram illustrating the second embodiment, in which (a) is a perspective view, and (b) is a cross-sectional view taken along the line VI-VI in (a).
In the welding joining process according to the second embodiment, the welding joining is performed along the abutting portion J1 (unplasticized region j) on the first side face C and the second side face D side without providing the groove K. And as shown in FIG.13 (b), the build-up part T 'which protruded from the 2nd side D among the weld metals T is excised, and the surface of the 1st side C and the 2nd side D is made smooth. You may finish it. Even with such a joining method, the airtightness and watertightness between both side surfaces of the metal member 1 to be joined can be improved.

  As mentioned above, although embodiment of this invention was described in detail, in the range which does not deviate from the meaning of this invention, it can change suitably. For example, in the present embodiment, the welding joining process is performed on both side surfaces of the metal member 1 to be joined, but the present invention is not limited to this, and it is only necessary to perform welding joining on one of the side surfaces. Further, the rotation direction and the traveling direction of the main rotating tool G for joining are not limited to those described above.

  In the welding joining process, TIG welding or MIG welding is employed in the present embodiment, but it is merely an example, and other welding joining may be used. In addition, the friction stirrer according to the present embodiment performs the friction stir from above the metal member to be joined, but is not limited to this, and the rotary tool for main welding around the metal member to be joined. Friction stirring may be performed while G moves. Further, the friction stir paths according to the first preliminary process, the first main joining process, the second preliminary process, and the second main joining process are merely examples, and may be other paths. The first metal member 1a and the second metal member 1b may be hollow members.

It is the figure which showed the joining method which concerns on 1st embodiment, Comprising: (a) is a perspective view, (b) is an expansion perspective view in the N section of (a). It is the figure which showed the (1) 1st preparatory process which concerns on 1st embodiment, (a) is a perspective view, (b) is a top view. (1) It is the figure which showed 1st preparatory process which concerns on 1st embodiment, (a) is II sectional view taken on the line of (b) of FIG. 2, (b) is (b) of FIG. Is a sectional view taken along line II-II in FIG. It is the figure which showed the rotary tool which concerns on 1st embodiment, Comprising: (a) is a side view of the rotary tool for temporary joining, (b) is a side view of the rotary tool for main joining. It is the figure which showed the use condition of the rotary tool for temporary joining which concerns on 1st embodiment, (a) is the figure which made the rotary tool for temporary joining contact the 2nd tab material, (b) These are the figures which pushed the rotation tool for temporary joining into the 2nd tab material. It is the top view which showed the 2nd tab material joining process of the 1st preliminary process which concerns on 1st embodiment, the temporary joining process, and the 1st tab material joining process. It is sectional drawing which showed the 1st main joining process which concerns on 1st embodiment by the III-III arrow direction of FIG. 6, Comprising: (a) is a starting position part, (b) is an intermediate part, (c ) Is a diagram showing the friction stir welding at the end position portion. (A) is sectional drawing which faces the 1st metal member 1a side from the abutting part J1 after the 2nd preparatory process which concerns on 1st embodiment. (B) is the top view which showed the 1st tab material joining process of the 2nd preparation process which concerns on 1st embodiment, a temporary joining process, and the 2nd tab material joining process. 8B is a cross-sectional view taken along the line IV-IV in FIG. 8B showing the second main joining step according to the first embodiment, where FIG. 8A is a start position portion, and FIG. 8B is a friction at an intermediate portion. It is the figure which showed stirring joining. It is the perspective view which showed the to-be-joined metal member after the tab material cutting process which concerns on 1st embodiment. It is the perspective view which showed the ditch | groove formation process which concerns on 1st embodiment. It is the figure which showed the welding joining process which concerns on 1st embodiment, Comprising: (a) is the front view seen from the 2nd side surface, (b) is VV arrow sectional drawing of (a). . It is the figure which showed the joining method which concerns on 2nd embodiment, Comprising: (a) is a perspective view, (b) is VI-VI arrow sectional drawing of (a). It is the perspective view which showed the conventional joining method. It is the perspective view which showed the conventional joining method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal member to be joined 1a 1st metal member 1b 2nd metal member 2 1st tab material 3 2nd tab material A surface B back surface C 1st side surface D 2nd side surface F rotary tool for temporary joining G rotational tool for this joining J1 ~J3 butting portion K groove P1~P4 prepared hole R _{1, R 2} tunnel-shaped cavity defects S ₁ to S ₄ oxide film T weld metal W1~W4 start position of the plasticized region S _M main bonding step E _M main bonding step End position

Claims (5)

A joining method in which a frictional stirring is performed by moving a rotating tool with respect to a metal member to be joined formed by abutting a first metal member and a second metal member,
A first main joining step of performing frictional stirring on the surface of the metal member to be joined with respect to the abutting portion between the first metal member and the second metal member;
A second main joining step of performing frictional stirring on the back surface of the metal member to be joined with respect to the abutting portion;
A welding process for welding the side surfaces of the metal members to be joined to the abutting part, and
The welding joint process includes
The unplasticized region between the front side plasticized region formed in the first main joining step and the back side plasticized region formed in the second main joining step is covered with a weld metal and sealed. The joining method characterized by the above-mentioned. Before the welding and joining step, including a groove forming step of forming a groove along the abutting portion of the side surface of the metal member to be joined,
The joining method according to claim 1, wherein the weld metal is filled in the concave groove during the welding joining process.   The joining method according to claim 2, wherein a width of the concave groove is smaller than a width of the front surface side plasticized region and the rear surface side plasticized region.   The joining method according to any one of claims 1 to 3, wherein a portion protruding from a side surface of the weld metal is cut out after the welding joining step. The joining method according to any one of claims 1 to 4, wherein a pilot hole is formed in advance at a position where the rotary tool is to be inserted.

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