JP2019188420A - Friction stir welding method - Google Patents

Abstract

To provide a friction stir welding method in which an uneven recessed groove on a surface of a metal member can be formed smaller and surface roughness of a welded surface can be reduced.SOLUTION: A taper angle of a base end-side pin F2 is set to be larger than a taper angle of a tip-side pin F3. A stair-like uneven part is formed on an outer peripheral surface of the base end-side pin F2, and a flat face F4 perpendicular to a rotating shaft of a rotary tool F for main welding is formed and also a protrusion part F5 that protrudes to the flat face F4 is formed at a tip side of the tip-side pin F3. Friction stirring is performed to a butted part J1 by inserting a tip surface F6 of the protrusion part F5 deeper than a position of an outer peripheral surface 13a of a small diameter part 3 of a first metal member 1a while contacting the base end-side pin F2 and the flat face F4 with the first metal member 1a and a second metal member 1b.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a friction stir welding method.

  As a rotary tool used for friction stir welding, a tool including a shoulder portion and a stirring pin hanging from the shoulder portion is known. The rotary tool performs friction stir welding in a state where the lower end surface of the shoulder portion is pushed into the metal member. By pushing the shoulder portion into the metal member, the plastic fluidizing material can be pressed to suppress the generation of burrs. However, there is a problem that if the height position of the joint is changed, defects are likely to occur, the stepped groove becomes large and a lot of burrs are generated.

  On the other hand, it is a friction stir welding method for joining two metal members using a rotary tool equipped with a stirring pin, and the rotating stirring pin is inserted into the abutting portion between the metal members, and only the stirring pin contacts the metal member There is known a friction stir welding method including a main joining step of performing friction stir welding in a state of being made (Patent Document 1). According to the prior art, a spiral groove is engraved on the outer peripheral surface of the stirring pin, and in order to perform friction stir welding with the base end exposed while only the stirring pin is in contact with the member to be joined, The occurrence of defects can be suppressed even when the height position of the joint changes, and the load on the friction stirrer can be reduced. However, since the plastic fluid material cannot be pressed by the shoulder portion, there is a problem that the stepped groove on the surface of the metal member becomes large and the bonding surface roughness becomes large. Further, there is a problem that a bulging portion (a portion where the surface of the metal member swells compared to before joining) is formed on the side of the step groove.

  On the other hand, Patent Document 2 describes a rotary tool including a shoulder portion and a stirring pin that hangs down from the shoulder portion. Tapered surfaces are formed on the outer peripheral surfaces of the shoulder portion and the stirring pin, respectively. A spiral groove in plan view is formed on the tapered surface of the shoulder portion. The cross-sectional shape of the groove is semicircular. By providing the tapered surface, the metal member can be stably joined even if the thickness of the metal member and the height position of the joining change. In addition, when the plastic fluidized material enters the groove, the flow of the plastic fluidized material can be controlled to form a suitable plasticized region.

JP 2013-39613 A Japanese Patent No. 4210148

  However, in the prior art of Patent Document 2, since the plastic fluid material enters the groove of the tapered surface, there is a problem that the groove does not function. Further, when the plastic fluid material enters the groove, the plastic fluid material is frictionally agitated with the plastic fluid material adhering to the groove, so that there is a problem that the welded metal member and the deposits rub against each other to deteriorate the joining quality. Furthermore, there are problems that the surface of the metal member to be joined becomes rough, burrs increase, and the stepped grooves on the surface of the metal member also increase.

  From such a viewpoint, an object of the present invention is to provide a friction stir welding method capable of reducing the stepped groove on the surface of the metal member and reducing the bonding surface roughness.

  In order to solve such problems, the present invention provides a columnar first metal member having a small diameter portion at an end of a large diameter portion, and a cylindrical second metal member having an outer diameter substantially equal to the large diameter portion. A friction stir welding method for performing friction stir using a rotary tool including a base end side pin and a front end side pin to a butted portion of a metal member to be joined formed by abutting end surfaces of metal members. The taper angle of the end-side pin is larger than the taper angle of the distal-end side pin, and a stepped step portion is formed on the outer peripheral surface of the base-end side pin. While inserting the distal end side pin into the abutting portion, the rotating tool is moved to the metal to be joined while the outer peripheral surface of the proximal end pin is in contact with the outer peripheral surfaces of the first metal member and the second metal member. It is characterized by making a round around the member.

  The present invention also provides a first metal member having a columnar small diameter portion at an end of a columnar large diameter portion, and a cylindrical second metal member having an outer diameter substantially equal to the large diameter portion. A friction stir welding method for performing friction stir using a rotary tool having a base end side pin and a front end side pin against a butted portion of a metal member to be joined formed by abutting the end surfaces of the base end side pins, The taper angle of the distal end side pin is larger than the taper angle of the distal end side pin, a stepped step portion is formed on the outer peripheral surface of the proximal end side pin, and the distal end side pin of the rotated rotating tool is Is inserted into the abutting portion while the outer peripheral surface of the base end side pin is in contact with the outer peripheral surfaces of the first metal member and the second metal member, and the rotating tool is disposed around the metal member to be bonded. It is characterized by making a full circle.

  According to such a joining method, the metal member can be pressed by the outer peripheral surface of the base end side pin having a large taper angle, so that the step groove on the joint surface can be reduced and formed on the side of the step groove. The bulging portion can be eliminated or reduced. Since the stepped step portion is shallow and the outlet is wide, even if the metal member is pressed by the base end side pin, the plastic fluidized material hardly adheres to the outer peripheral surface of the base end side pin. For this reason, the bonding surface roughness can be reduced, and the bonding quality can be suitably stabilized. Moreover, it can insert easily to a deep position by providing a front end side pin.

  Moreover, it is preferable that the start end and the termination | terminus of the plasticization area | region formed in the said butt | matching part overlap, and a part of said plasticization area | region overlaps. According to this joining method, the watertightness and airtightness of the joint can be improved by overlapping a part of the plasticized region.

  Moreover, it is preferable to make a round around the said to-be-joined metal member in the state which located the rotation center axis | shaft of the said rotation tool in the said 1st metal member side rather than the said abutting part. There is a possibility that a bonding defect is formed in the plasticized region formed by friction stir welding, and if the bonding defect is formed on the second metal member side which is a hollow member, there is a possibility that the water tightness and the air tightness are lowered. is there. However, according to such a joining method, even if a joining defect is formed, since it is formed at a position away from the second metal member, it is possible to suppress a decrease in watertightness and airtightness.

  Further, when the first metal member is located on the left side in the advancing direction of the rotary tool, the rotary tool is rotated to the right, and when the first metal member is located on the right side in the advancing direction of the rotary tool, the rotary tool is It is preferable to rotate counterclockwise. In friction stir welding, there is a possibility that a joint defect may occur on the left side in the traveling direction when the rotary tool is rotated to the right, and on the right side in the traveling direction when the rotary tool is rotated to the left. If formed, water tightness and air tightness may be lowered. However, according to such a joining method, even if a joining defect is formed, the joining method is formed at a position away from the second metal member, so that it is possible to suppress a decrease in watertightness and airtightness.

  Further, it is preferable that the rotary tool is moved toward the first metal member from the end of the plasticized region formed in the butting portion, and the drawing position of the rotary tool is provided in the first metal member. According to such a joining method, it is possible to prevent the metal material from flowing into the metal member to be joined. Moreover, since the extraction trace of the rotary tool is formed at a position away from the second metal member, it is possible to suppress a decrease in water tightness and air tightness.

  In addition, prior to the step of friction stir welding with the rotary tool, it is preferable that a part of the butting portion is temporarily joined using a temporary joining rotary tool smaller than the rotary tool. According to this joining method, it is possible to prevent the opening of the first metal member and the second metal member when performing frictional stirring with the rotary tool.

  In addition, a flat surface perpendicular to the rotation axis of the rotary tool is formed on the distal end side of the distal end side pin, and a protrusion protruding to the flat surface is formed. The front end surface of the protrusion is inserted deeper than the position of the outer peripheral surface of the small diameter portion of the first metal member while the surface is in contact with the first metal member and the second metal member. It is preferable to carry out friction stirring. According to this joining method, the plastic fluidized material that is frictionally stirred along the protrusion and wound up on the protrusion is pressed on the flat surface. Accordingly, the periphery of the protrusion can be more reliably frictionally stirred, and the oxide film at the interface can be reliably divided, so that the bonding strength can be increased.

  According to the friction stir welding method according to the present invention, the stepped grooves on the surface of the metal member can be reduced and the bonding surface roughness can be reduced.

It is a side view which shows the rotary tool for this joining used for the joining method which concerns on embodiment of this invention. It is an expanded sectional view of the rotation tool for this joining. It is sectional drawing which shows the 1st modification of this rotation tool for joining. It is sectional drawing which shows the 2nd modification of this rotation tool for joining. It is sectional drawing which shows the 3rd modification of this rotation tool for joining. It is a disassembled perspective view which shows the to-be-joined metal member which concerns on 1st embodiment of this invention. It is sectional drawing which shows the butt | matching state of the to-be-joined metal member which concerns on 1st embodiment of this invention. It is a perspective view which shows the state which joined the to-be-joined metal member which concerns on 1st embodiment. It is a perspective view which shows the temporary joining process of the friction stir welding method which concerns on 1st embodiment. It is a perspective view which shows the start stage of the main joining process of the friction stir welding method which concerns on 1st embodiment. It is II sectional drawing of FIG. It is a perspective view which shows the middle stage of the main joining process of the friction stir welding method which concerns on 1st embodiment. It is a perspective view which shows the completion | finish stage of the main joining process of the friction stir welding method which concerns on 1st embodiment. It is a conceptual diagram which shows the conventional rotation tool. It is a conceptual diagram which shows the conventional rotation tool. It is sectional drawing which shows the modification of this joining process. It is a top view which shows the modification of this joining process.

  Embodiments of the present invention will be described with reference to the drawings as appropriate. First, the main welding rotary tool (rotary tool) F used in the bonding method according to the present embodiment will be described. The main rotating tool F for welding is a tool used for friction stir welding. As shown in FIG. 1, the main rotating tool for joining F is made of, for example, tool steel, and mainly includes a base shaft portion F1, a base end side pin F2, and a front end side 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 base end side pin F2 is continuous with the base shaft portion F1 and tapers toward the tip. The proximal end pin F2 has a truncated cone shape. The taper angle A of the base end side pin F2 may be set as appropriate, and is, for example, 135 to 160 °. When the taper angle A is less than 135 ° or exceeds 160 °, the joint surface roughness after frictional stirring becomes large. The taper angle A is larger than the taper angle B of the distal end side pin F3 described later. As shown in FIG. 2, a stepped step portion F21 is formed over the entire height direction on the outer peripheral surface of the proximal end side pin F2. The step portion F21 is formed in a spiral shape clockwise or counterclockwise. That is, the stepped portion F21 has a spiral shape in plan view and a step shape in side view. In the present embodiment, the stepped portion F21 is set counterclockwise from the proximal end side toward the distal end side in order to rotate the main welding rotary tool F to the right.

  In addition, when rotating this welding rotation tool F counterclockwise, it is preferable to set the stepped portion F21 clockwise from the base end side to the tip end side. Thereby, since the plastic fluidized material is guided to the front end side by the step portion F21, the metal overflowing to the outside of the metal member to be joined can be reduced. The step portion F21 includes a step bottom surface F21a and a step side surface F21b. A distance X1 (horizontal direction distance) between the vertices F21c and F21c of the adjacent stepped portions F21 is appropriately set according to a step angle C and a height Y1 of the step side surface F21b described later.

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

  The step angle C formed by the step bottom surface F21a and the step side surface F21b may be set as appropriate, and is set at 85 to 120 °, for example. In this embodiment, the step bottom surface F21a is parallel to the horizontal plane. The step bottom surface F21a may be inclined in the range of −5 ° to 15 ° with respect to the horizontal plane from the rotation axis of the tool toward the outer circumferential direction (minus is downward with respect to the horizontal plane, plus is with respect to the horizontal plane). Top). 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 the plastic fluidized material stays inside the stepped portion F21 and does not adhere to the outside when performing friction stirring. It sets suitably so that it may come out and a joint surface roughness can be made small by pressing a plastic fluid material in level difference bottom F21a.

  As shown in FIG. 1, the distal end side pin F3 is formed continuously with the proximal end side pin F2. The distal end side pin F3 has a truncated cone shape. A flat surface F4 perpendicular to the rotation axis is formed at the tip of the tip side pin F3. Further, the front end side pin F3 is formed with a protrusion F5 that protrudes from the flat surface F4. That is, a step portion is formed by the flat surface F4 and the protrusion F5. The protrusion F5 is coaxial with the distal end side pin F3. The shape of the protrusion F5 is not particularly limited, but in the present embodiment, it has a cylindrical shape. A spiral groove may be formed on the side surface of the protrusion F5.

  The taper angle B of the distal end side pin F3 is smaller than the taper angle A of the proximal end side pin F2. As shown in FIG. 2, a spiral groove F31 is formed on the outer peripheral surface of the distal end side pin F3. The spiral groove F31 may be either clockwise or counterclockwise. In this embodiment, the spiral groove F31 is engraved counterclockwise from the base end side toward the distal end side in order to rotate the main welding rotary tool F to the right.

  In addition, when rotating this welding rotation tool F counterclockwise, it is preferable to set the spiral groove F31 clockwise from the proximal end side toward the distal end side. Thereby, since the plastic fluid material is guided to the front end side by the spiral groove F31, the metal overflowing to the outside of the metal member to be joined can be reduced. The spiral groove F31 includes a spiral bottom surface F31a and a spiral side surface F31b. A distance (horizontal direction distance) between vertices F31c and F31c of adjacent spiral grooves F31 is defined as a 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 °. The spiral groove F31 has a function of increasing the frictional heat by coming into contact with the metal member to be joined and guiding the plastic fluid material to the tip side.

  The design of the joining 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 main rotating tool FA according to the first modification, the step angle C formed by the step bottom surface F21a and the step side surface F21b of the step portion F21 is 85 °. The step bottom surface F21a is parallel to the horizontal plane. As described above, the step bottom surface F21a is parallel to the horizontal plane, and the step angle C may be an acute angle within a range in which the plastic fluidized material stays in the stepped portion F21 during frictional stirring and comes out to the outside.

  FIG. 4 is a side view showing a second modification of the welding rotary tool of the present invention. As shown in FIG. 4, in the main welding rotary tool FB according to the second modification, the step angle C of the step portion F <b> 21 is 115 °. The step bottom surface F21a is parallel to the horizontal plane. In this manner, the step bottom surface F21a is parallel to the horizontal plane, and the step angle C may be an obtuse angle within a range that functions as the step portion F21.

  FIG. 5 is a side view showing a third modification of the rotating tool for bonding according to the present invention. As shown in FIG. 5, in the main welding rotary tool FC according to the third modification, the step bottom surface F21a is inclined upward by 10 ° with respect to the horizontal plane from the rotation axis of the tool toward the outer peripheral direction. The step side surface F21b is parallel to the vertical surface. As described above, the step bottom surface F21a may be formed so as to incline above the horizontal plane from the rotation axis of the tool toward the outer periphery in a range in which the plastic fluid material can be pressed during the friction stirring. Also according to the first to third modified examples of the main rotating tool for joining described above, an effect equivalent to that of the following embodiment can be obtained.

  Next, the 1st metal member 1a and the 2nd metal member 1b joined by this embodiment are demonstrated. As shown in FIGS. 6A and 6B, in the present embodiment, the substantially cylindrical first metal member 1a and the cylindrical second metal member 1b are joined by friction stirring.

  As shown in FIG. 6A, the first metal member 1 a is a metal member that has a substantially cylindrical shape, and has a large diameter portion 2 and a small diameter portion 3 that has a cylindrical shape protruding from the end surface 11 a of the large diameter portion 2. And have. The large diameter portion 2 and the small diameter portion 3 are formed by concentric shafts. The second metal member 1b is a metal member having a cylindrical shape. The first metal member 1a and the second metal member 1b have substantially the same outer diameter, and the outer diameter of the small diameter portion 3 of the first metal member 1a and the inner diameter of the second metal member 1b are formed to be substantially equal. Yes.

  The first metal member 1a and the second metal member 1b are appropriately selected from metals capable of friction stirring such as aluminum, aluminum alloy, copper, copper alloy, titanium, titanium alloy, magnesium, and magnesium alloy. In the present embodiment, the first metal member 1a and the second metal member 1b are formed of the same metal material, but different metal materials may be used.

  As shown in FIG. 7, the to-be-joined metal member 1 formed by abutting the first metal member 1a and the second metal member 1b makes the relative rotation tool F (see FIG. 1) relative to the outer peripheral surface. It is moved and integrated by friction stir welding. For example, a sealed container, a torque rod, or the like can be formed by the friction stir welding method according to the present embodiment.

  Next, the friction stir welding method according to the first metal member embodiment will be described. In the friction stir welding process according to the present embodiment, a butt process, a temporary bonding process, and a main bonding process are performed.

  As shown in FIGS. 6A and 6B, the butting process is a process of forming the metal member 1 to be joined by butting the first metal member 1 a and the second metal member 1 b at the end surfaces. That is, the end surface 11a of the first metal member 1a and the end surface 11b of the second metal member 1b are brought into close contact with each other. As described above, the outer diameter of the first metal member 1a (the outer diameter of the large-diameter portion 2) and the outer diameter of the second metal member 1b are substantially the same. The outer peripheral surfaces 12a and 12b are flush with each other. Moreover, since the outer diameter of the small diameter part 3 of the 1st metal member 1a and the internal diameter of the 2nd metal member 1b are formed substantially equal, when both members are faced, the outer peripheral surface 13a of the small diameter part 3 and the first The inner peripheral surface 13b of the bimetallic member 1b is in surface contact.

  As shown in FIG. 6B, the end face 11a of the first metal member 1a and the end face 11b of the second metal member 1b are abutted to form a butt portion J1. The butted portion J1 is continuously formed over the outer peripheral surface of the metal member 1 to be joined. The abutting portion J2 is formed by abutting the outer peripheral surface 13a of the small diameter portion 3 and the inner peripheral surface 13b of the second metal member 1b. The metal member 1 to be bonded is fixed so as not to move to a fixing jig that can rotate around an axis.

  As shown in FIG. 8, the temporary joining step is a step of temporarily joining the butt joint J1. In the temporary joining step, the temporary joining rotary tool G rotated clockwise is relatively moved along the abutting portion J1. In the present embodiment, the metal member 1 to be bonded is rotated around the axis while the rotary tool G for temporary bonding is driven to rotate around the rotation axis. In this embodiment, when the temporary joining rotary tool G moves relative to the metal member 1 to be joined, the first metal member 1a is set on the left side in the traveling direction. The temporary joining step may be performed continuously along the butt portion J1, or may be performed intermittently as in the present embodiment.

  As shown in FIG. 9, the main joining step is a step of performing friction stir welding on the abutting portion J1 in earnest using the main joining rotating tool F including the proximal end side pin F2 and the distal end side pin F3. is there. In the main joining step, first, the main welding rotating tool F rotated to the right is inserted into the start position s1 set in the first metal member 1a. Then, the main welding rotary tool F is relatively moved toward the first intermediate point s2 set in the abutting portion J1. The end portion (starting end Wa) of the plasticizing region W at the first intermediate point s2 is a portion that becomes the “starting end of the plasticizing region formed in the butt portion” in the claims.

  When the main welding rotary tool F reaches the first intermediate point s2, the metal member 1 to be bonded is rotated around the axis. In this embodiment, the to-be-joined metal member 1 is rotated so that the first metal member 1a is arranged on the left side with respect to the traveling direction of the main joining rotary tool F. In addition, when rotating the rotation tool F for main joining counterclockwise, the to-be-joined metal member 1 is rotated so that the 1st metal member 1a may be arrange | positioned with respect to the advancing direction of the rotation tool F for main joining.

  As shown in FIG. 10, in the main joining step, friction stir welding is performed in a state where the base end side pin F2 and the front end side pin F3 are in contact with the first metal member 1a and the second metal member 1b. Friction stir welding is performed while pressing the first metal member 1a and the second metal member 1b on the outer peripheral surface of the proximal end side pin F2 while inserting the distal end side pin F3 of the rotating tool F for main joining to be rotated into the abutting portion J1. . That is, friction stir welding is performed in a state where the outer peripheral surface of the base end side pin F2 is in contact with the outer peripheral surface 12a of the first metal member 1a and the outer peripheral surface 12b of the second metal member 1b. The insertion depth of the base end side pin F2 and the front end side pin F3 may be set as appropriate as long as the outer peripheral surface of the base end side pin F2 can press the first metal member 1a and the second metal member 1b. For example, the insertion depth of the base end side pin F2 and the front end side pin F3 is a range in which the outer peripheral surface of the base end side pin F2 can press the first metal member 1a and the second metal member 1b, and You may set so that the front end side pin F3 may reach the outer peripheral surface 13a of the small diameter part 3. FIG. In the present embodiment, the flat surface F4 is set to contact the first metal member 1a and the second metal member 1b, and the tip surface F6 of the protrusion F5 is set to contact only the first metal member 1a. That is, the front end surface F6 of the protrusion F5 is inserted deeper than the position of the outer peripheral surface 13a of the small diameter portion 3 of the first metal member 1a. Moreover, in this embodiment, it has set so that the center part of the height direction of the outer peripheral surface of the base end side pin F2 may contact the 1st metal member 1a and the 2nd metal member 1b. Then, as shown in FIG. 11A, the main joining rotary tool F is moved relative to the metal member 1 to be joined along the abutting portion J1 while maintaining a constant height. A plasticized region W is formed on the movement trajectory of the main rotating tool for welding F.

  When the rotation tool F for main welding makes a round of the abutting portion J1, the first intermediate point s2 is passed through to the second intermediate point s3. As shown in FIG. 11B, the end portion (termination Wb) of the plasticized region W at the second intermediate point s3 is a portion that becomes “the end of the plasticized region formed in the butt portion” in the claims. When the main welding rotary tool F reaches the second intermediate point s3, the rotation of the bonded metal member 1 around the axis is stopped. Then, the main joining rotary tool F is relatively moved to the end position (drawing position) e1 set on the first metal member 1a, and the main joining rotary tool F is detached from the metal member 1 to be joined.

  When the extraction trace of the main joining rotary tool F remains on the metal member 1 to be joined, for example, a repairing process for repairing by overlay welding may be performed.

  Here, for example, as shown in FIG. 12A, in the case of the conventional rotary tool 200, the shoulder portion cannot hold the surface of the metal member 210 to be bonded, so that the stepped groove (the surface of the metal member 1 to be bonded and the plasticized region) There is a problem that the concave surface groove formed with the surface of W becomes large and the bonding surface roughness becomes large. Further, there is a problem that a bulging portion (a portion where the surface of the bonded metal member 1 swells compared to before joining) is formed on the side of the step groove. On the other hand, when the taper angle β of the rotary tool 201 is larger than the taper angle α of the rotary tool 200 as in the rotary tool 201 of FIG. 12B, the surface of the metal member 210 to be bonded can be pressed compared to the rotary tool 200. For this reason, the step groove is reduced and the bulging portion is also reduced. However, since the downward plastic flow becomes strong, a kissing bond is likely to be formed below the plasticized region W.

  On the other hand, the main rotating tool F for joining according to the present embodiment includes a base end side pin F2 and a front end side pin F3 having a taper angle smaller than the taper angle A of the base end side pin F2. . Thereby, it becomes easy to insert the rotation tool F for main joining into the butt | matching part J1. Further, since the taper angle B of the distal end side pin F3 is small, the main joining rotary tool F can be easily inserted to a deep position of the butt portion J1. Further, since the taper angle B of the distal end side pin F3 is small, downward plastic flow can be suppressed as compared with the rotary tool 201. For this reason, it is possible to prevent a kissing bond from being formed below the plasticized region W. On the other hand, since the taper angle A of the base end side pin F2 is large, even if the thickness of the to-be-joined metal member 1 or the height position of joining changes compared with the conventional rotary tool, it can be joined stably.

  In addition, since the plastic fluid can be pressed by the outer peripheral surface of the base end side pin F2, the stepped groove formed on the joining surface can be reduced, and the bulge formed on the side of the stepped groove. Can be eliminated or reduced. Further, since the stepped step portion F21 is shallow and has a wide outlet, the plastic fluid material can easily come out of the step portion F21 while pressing the plastic fluid material with the step bottom surface F21a. Therefore, even if the plastic fluid material is pressed by the proximal pin F2, the plastic fluid material is difficult to adhere to the outer peripheral surface of the proximal pin F2. Therefore, the bonding surface roughness can be reduced and the bonding quality can be suitably stabilized.

  Further, since the projection F5 is formed on the flat surface F4 on the distal end side of the distal end side pin F3, the plastic fluid material that is frictionally stirred along the projection F5 and wound up on the projection F5 is pressed by the flat surface F4. It is done. Accordingly, the friction stir around the protrusion F5 can be more reliably performed, and the oxide film of the abutting portions J1 and J2 can be reliably divided, so that the bonding strength of the abutting portions J1 and J2 can be increased.

  Further, in the main joining step of the present embodiment, since the start end Wa and the end end Wb of the plasticized region W overlap and a part of the plasticized region W overlaps, the water tightness and the air tightness of the joint portion. Can be improved.

  Further, if the main welding rotary tool F is rotated to the right as in the present embodiment, there is a risk that a bonding defect may occur on the left side in the traveling direction. It set so that the metal member 1a might arrange | position. Thereby, even if a joint defect is formed, it is formed on the first metal member 1a side which is a solid member. That is, since a joint defect is formed at a position separated from the second metal member 1b, which is a hollow member, it is possible to suppress a decrease in watertightness and airtightness.

  Further, according to the present embodiment, the main welding rotary tool F is moved to the first metal member 1a side with respect to the plasticizing region W, and the main welding rotary tool F is pulled out on the first metal member 1a. The drawing trace can be formed at a position far from the second metal member 1b which is a hollow member. Thereby, the fall of watertightness and airtightness can be suppressed. Further, when the main joining rotary tool F is moved to the second metal member 1b side from the plasticizing region W, the metal material may flow out into the metal member 1 to be joined, but according to the present embodiment. The problem can be solved.

  In addition, by performing the temporary joining step before the main joining step, it is possible to prevent the first metal member 1a and the second metal member 1b from opening during the main joining step.

<Modification>
Next, a modified example of the present invention will be described. In the main joining step of the embodiment shown in FIG. 10 described above, friction stir welding was performed by setting so that the rotation center axis C of the main welding rotary tool F and the butting portion J1 overlap each other. In the main joining process of the modified example, as shown in FIG. 13A and FIG. 13B, the friction is performed in a state where the rotation center axis C of the main welding rotary tool F is positioned on the first metal member 1a side with respect to the butted portion J1. Stir welding is performed.

  As shown in FIGS. 13A and 13B, also in the main joining process, since the main welding rotary tool F is rotated to the right, the first metal member 1a on the left side with respect to the traveling direction of the main welding rotary tool F is shown. Set to be placed. Also in the main joining process according to the modified example, the butted portion J1 is frictionally stirred, and the first metal member 1a and the second metal member 1b are joined.

  According to the modification, there is a possibility that a bonding defect is formed on the left side in the traveling direction of the main rotating tool F for bonding, but the bonding defect can be formed on the first metal member 1a side which is a solid member. That is, the joint defect in the modified example is formed at a position further away from the second metal member 1b than in the above-described embodiment. Thereby, the fall of the watertightness of the to-be-joined metal member 1 and airtightness can be suppressed more.

  In this modification, the entire height direction of the abutting portion J1 is set to be frictionally stirred. However, the rotation center axis C of the rotary tool F for main welding is such that at least a part of the abutting portion J1 is frictionally stirred. The welding rotary tool F may be moved in a state where is positioned on the first metal member 1a side.

  Although the embodiments and modifications of the present invention have been described above, design changes can be made as appropriate without departing from the spirit of the present invention. For example, the temporary joining step may be performed using the main joining rotating tool F. Moreover, you may perform a temporary joining process by welding.

  Moreover, in this embodiment, although the columnar member and the cylindrical member were joined, it is not limited to this. Other shapes may be used as long as they join a large-diameter portion and a columnar metal member provided with a small-diameter portion in the large-diameter portion and a cylindrical member.

  Moreover, in this embodiment, although the main welding rotation tool F is rotated to the right, it may be rotated to the left. In this case, it arrange | positions so that the 1st metal member 1a may come to the right side of the advancing direction of this rotation tool F for this joining. By setting in this way, an effect equivalent to that of the embodiment can be obtained.

  Moreover, in this embodiment, although this rotation tool F for this joining was made to make one round with respect to the butt | matching part J1, you may make it make two or more rounds. By making two rounds, the joint defect generated in the first round can be frictionally stirred again, so that watertightness and airtightness can be improved. Further, after the second round, the friction stirring may be performed while shifting the main welding rotary tool F toward the first metal member 1a. By doing in this way, a joint defect can be repaired reliably.

  Moreover, when the main joining process is completed, a burr cutting process for cutting off burrs appearing on the surface of the metal member 1 to be joined may be performed. By performing the burr cutting process, the surfaces of the first metal member 1a and the second metal member 1b can be finished finely.

  In the present embodiment, the main-use rotating tool F in which the flat surface F4 and the protrusion F5 are formed on the distal end side of the distal end side pin F3 is used. However, the flat surface F4 and the protrusion are disposed on the distal end side of the distal end side pin F3. You may use the rotation tool F for this joining without the part F5.

DESCRIPTION OF SYMBOLS 1 Metal member to be joined 1a 1st metal member 1b 2nd metal member 2 Large diameter part 3 Small diameter part C Rotation center axis F Rotating tool for rotation (rotary tool)
F2 Base end side pin F3 Front end side pin F4 Flat surface F5 Protruding part G Temporary joining rotary tool J1 Abutting part J2 Abutting part W Plasticization region Wa Start end Wb End

Claims (8)

A column-shaped first metal member having a small-diameter portion at the end of the large-diameter portion and a cylindrical second metal member having an outer diameter substantially equal to that of the large-diameter portion are abutted at the end surfaces. A friction stir welding method for performing friction stir using a rotating tool having a base end side pin and a front end side pin with respect to the butted portion of the joining metal member,
The taper angle of the proximal pin is larger than the taper angle of the distal pin,
A stepped step portion is formed on the outer peripheral surface of the base end side pin,
While inserting the distal end side pin of the rotated rotating tool into the abutting portion, the outer peripheral surface of the proximal end side pin is in contact with the outer peripheral surface of the first metal member and the second metal member, A friction stir welding method comprising rotating a rotating tool around the metal member to be joined.   2. The friction stir welding method according to claim 1, wherein a start end and an end of a plasticized region formed in the butt portion overlap each other, and a part of the plasticized region overlaps.   The rotation center axis of the rotary tool is caused to make a round around the metal member to be joined in a state where the rotation center axis is located closer to the first metal member than the abutting portion. Friction stir welding method. When the first metal member is located on the left side in the traveling direction of the rotary tool, rotate the rotary tool to the right,
4. The friction stir welding method according to claim 1, wherein when the first metal member is positioned on the right side in the traveling direction of the rotary tool, the rotary tool is rotated counterclockwise.   The rotary tool is moved toward the first metal member from the end of the plasticizing region formed in the abutting portion, and the drawing position of the rotary tool is provided in the first metal member. The friction stir welding method according to any one of claims 1 to 4.   Prior to the step of friction stir welding with the rotary tool, a part of the butting portion is temporarily joined using a rotary tool for temporary joining that is smaller than the rotary tool. The friction stir welding method according to any one of the above. A first metal member having a cylindrical small-diameter portion at the end of a cylindrical large-diameter portion and a cylindrical second metal member having an outer diameter substantially equal to the large-diameter portion are butted against each other at the end surfaces. A friction stir welding method for performing friction stir using a rotary tool provided with a base end side pin and a front end side pin with respect to a butt portion of the formed metal member to be joined,
The taper angle of the proximal pin is larger than the taper angle of the distal pin,
A stepped step portion is formed on the outer peripheral surface of the base end side pin,
While inserting the distal end side pin of the rotated rotating tool into the abutting portion, the outer peripheral surface of the proximal end side pin is in contact with the outer peripheral surface of the first metal member and the second metal member, A friction stir welding method comprising rotating a rotating tool around the metal member to be joined. On the distal end side of the distal end side pin, a flat surface perpendicular to the rotation axis of the rotary tool is formed, and a projection protruding to the flat surface is formed,
While the proximal pin and the flat surface are in contact with the first metal member and the second metal member, the distal end surface of the protrusion is deeper than the position of the outer peripheral surface of the small diameter portion of the first metal member. The friction stir welding method according to any one of claims 1 to 7, wherein the friction stir is performed with respect to the butt portion by insertion.

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