JP2007167902A - Friction stir joining method and rotary tool for friction stir joining - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction stir joining method capable of reducing a load applied on an equipment while securing joining strength when conducting friction stir joining, and to provide a rotary tool for the friction stir joining. <P>SOLUTION: In the friction stir joining, an insertion depth (y) of a pin part, which is inserted into members 51, 52 to be joined, is made smaller than a pin-part projection length (x) of a pin part 21, which projects from a shoulder part 11 of a rotary tool 10. When heating and softening the members 51 to be joined that surrounds the pin part 21, by frictional heat and inserting the pin part 21 to the insertion depth (y), the shoulder part 11 of the rotary tool 10 is not brought into direct contact with the member 51 to be joined, so that a joining load required in the joining is greatly reduced. Thus, the load that is applied to the equipment in the joining, i.e. an equipment load, is remarkably made small, and the equipment is miniaturized, so that equipment cost and running costs are remarkably reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a friction stir welding method for friction stir welding of members to be joined such as an aluminum alloy plate and a rotary tool for friction stir welding.

  Conventionally, as a method of joining plate-like members to be joined, there are mechanical joining using bolts and rivets or resistance spot welding. This resistance spot welding has a lighter product, fewer man-hours, and a relatively simple and widely used apparatus compared to mechanical joining using bolts and rivets.

  However, in resistance spot welding, the overlapped members to be joined are sandwiched between the welding electrodes facing each other, and the joined portion is heated to almost the melting temperature by the resistance heat generation, and is pressed and joined between the electrodes. Therefore, the welding electrode requires a large amount of electric power at the time of joining and the life of the welding electrode is short due to contamination and wear, and in addition to the welding power, the cooling water and air piping for cooling, and the wear electrode are consumed with use. Ancillary equipment such as a tip dresser for forming the top of the deformed welding electrode is required, and high equipment cost, running cost and maintenance cost are required. In addition, there is a concern about the influence on the working environment due to sputtering or the like scattered during the joining work.

  In particular, during resistance spot welding of aluminum alloy plates, etc., the welding electrode is heavily consumed, and if the welding spot is close, the current flow is reduced to the adjacent welding spot when energized, resulting in unstable welding joint performance. For this reason, the welding points cannot be brought close to each other, the continuous spot performance is poor, and the desired joint strength may not be obtained.

  As a countermeasure, for example, as shown in Patent Document 1, a rotating tool made of a material harder than a member to be joined is pressed against a joining point while rotating, and the joining point is heated and softened by frictional heat and pressure and joined. There is friction stir welding in which the members to be joined in the vicinity of the point are agitated and joined.

  FIG. 9 is a view showing a tip portion of a rotary tool used for the friction stir welding, and FIG. 10 is a view showing a friction stir welding method.

  The rotary tool 101 has a cylindrical shape, and a cylindrical shoulder portion 102 is formed at the tip thereof. The bottom surface 103 of the shoulder portion 102 is formed in an inverted conical shape so that the center is recessed toward the proximal end side, and the pin portion 106 projects in the distal direction along the axis L from the most recessed center portion. Also, a corner portion 105 extending from the outer peripheral surface 104 to the bottom surface 103 of the shoulder portion 102 is formed with a so-called shoulder R that is smoothly connected in an arc shape, and a portion 107 where the bottom surface 103 and the pin portion 106 are connected is also smooth in an arc shape. A so-called corner R is formed so as to be continuous.

  As shown in FIG. 10A, the friction stir welding method using the rotary tool 101 is a joining point of two members 121 and 122 to be joined on the receiving surface 111a of the work receiving member 111 of the friction stir welding apparatus 100. Arrange them so that P coincides with the axis L. Then, the rotary tool 101 is lowered along the axis L while rotating at high speed.

  When the pin portion 106 of the rotary tool 101 reaches the member to be bonded 121, the member to be bonded 121 is heated and softened by frictional heat between the rotating pin portion 106 and the member to be bonded 121, and the pin portion 106 is inserted. When the pin portion 106 is inserted, the bottom surface 103 of the shoulder portion 102 also comes into contact with the member 121 to be joined, and the vicinity of the joint point P is further heated by frictional heat generated by the bottom surface 103 and the member 121 to be joined. A plastic flow is induced by rotating in a state where the pin portion 106 is inserted into the member 121 that has been heated and softened in this way, and the base material in the vicinity of the joint point P is stirred by the rotating pin portion 106. .

  In this manner, the vicinity of the joining point P is agitated by rotating the rotary tool 101 in a state where the tip 106a of the pin portion 106 exceeds the boundary surface 123 between the joined member 121 and the joined member 122. A plastic flow region is formed, and the joined members 121 and 122 are integrated at the joining point P. After stirring for a predetermined time, the rotary tool 101 is pulled out from the members to be joined 121 and 122 as shown in FIG. When the pin portion 106 is pulled out, the base material that has been plastically flowed is cured, and the joined members 121 and 122 are joined at the joining point P.

  Further, as shown in FIG. 11, when the pin portion 106 and the shoulder portion 102 of the rotary tool 101 are inserted into the members 121 and 122 in the friction stir welding, the mother pushed out and discharged by the pin portion 106 and the shoulder portion 102 is discharged. As shown in FIG. 12, the burr 124 is generated on the surface of the member 121 to be joined by the material 124 a. There is also known a friction stir welding rotary tool provided with a deburring cutter for removing the burr 124 generated on the surface of the member 121 to be joined on the outer periphery of the tip of the rotary tool (see, for example, Patent Document 2).

JP 2001-314982 A JP 2000-334578 A

  According to the friction stir welding described in Patent Document 1, while rotating the rotary tool 101 at a high speed, the pin portion 106 is pressed against the joining point P between the members 121 and 122 to be joined, and the joining point P is heated and softened by the frictional heat. Since the base material is stirred by inserting the pin portion 106 and the joining point P of the joined members 121 and 122 is joined by plastic flow, spot joining can be performed with an extremely small amount of electric power compared to resistance spot welding, and cooling can be performed. Cooling water and air and its incidental facilities are unnecessary. In addition, there is no spatter or the like, and the rotary tool 101 is hardly contaminated or worn out. The rotary tool 101 can be used for a long time, and maintenance costs and running costs can be reduced. Moreover, it is possible to arrange the joint points P close to each other, and it is possible to ensure excellent joint strength.

  However, in the friction stir welding, since the pin portion 106 and the shoulder portion 102 of the rotary tool 101 are inserted into the softened member 121 to be joined, a large pressing force, that is, a joining force, is required to insert the rotary tool 101 into the member 121 to be joined. It is necessary to apply a load.

  Here, as a result of earnest research experiments, the inventor made contact with the member 121 to be joined with respect to the pressing force required for insertion of the pin portion 106 into the member 121 to be joined, that is, the joining load, in the friction stir welding. Further, the present inventors have found that the joining load accompanying the insertion is extremely large, and that the joining load is caused by the time during which the shoulder portion 102 is inserted into the joined member 121, that is, the insertion depth. FIG. 13 is a diagram showing the transition of the welding load of the rotary tool 101 in this friction welding.

  Further, the diameter D of the shoulder portion 102 is usually about 2 to 3 times the diameter d of the pin portion 106, and the load due to the joining load required at the time of joining largely depends on the diameter D of the shoulder portion 102. At this time, particularly in the joining of materials having a large resistance against the insertion of the pin portion 106 and the shoulder portion 102, the load applied to the equipment at the time of joining, that is, the equipment load becomes extremely large, leading to an increase in equipment size and running costs. Increase factor.

  On the other hand, according to Patent Document 2, the appearance quality of the member to be joined can be ensured by removing the burrs generated on the surface of the member to be joined by friction stir welding with the deburring cutter provided in the rotary tool. However, since the rotating tool is provided with the deburring cutter, the rotating tool becomes complicated, resulting in an increase in equipment cost, and a deburring process for removing the deburred with the deburring cutter is unavoidable.

  Accordingly, a first object of the present invention made in view of such a point is to provide a friction stir welding method and a friction stir welding rotary tool that can reduce the equipment load while ensuring the bonding strength in friction stir welding. It is in.

  A second object of the present invention is to provide a friction stir welding method and a friction stir welding rotary tool that can further suppress the generation of burrs in addition to the first object.

  The invention of the friction stir welding method according to claim 1, which achieves the first object, has a rotary tool provided with a pin portion that coaxially projects along the axis from the bottom surface of a cylindrical shoulder portion, A pin whose pin portion is set in advance by rotating the rotating tool around the axis while pressing the pin portion against the joining point of the overlapped members to be welded and heat softening the member to be joined around the pin portion by frictional heat. After the parts to be inserted are inserted to the depth of insertion, the members to be joined in the vicinity of the joining point are agitated by the rotating pin part, and the members to be joined are integrated at the joining point, and then pulled out along the axis line to join the parts to be joined. In the friction stir welding method for spot welding, the pin portion insertion depth is smaller than the pin portion protruding length of the pin portion protruding from the shoulder portion.

  According to a second aspect of the present invention, in the friction stir welding method according to the first aspect, the member is pushed out between the member to be joined and the bottom surface of the shoulder portion as the pin portion is inserted into the pin portion insertion depth. The volume of the base material is the volume of the discharged base material, and the volume between the member to be joined and the bottom surface of the shoulder portion when the pin portion is inserted into the pin portion insertion depth is the shoulder portion volume. The volume is ≧ 1.

  The invention according to claim 3, which achieves the second object, is the friction stir welding method according to claim 1, wherein the member to be joined and the shoulder portion are accompanied by insertion of the pin portion into the pin portion insertion depth. The volume of the base material extruded between the bottom surface of the base material and the bottom portion of the shoulder portion when the volume of the base material to be extruded and the bottom surface of the shoulder portion when the pin portion is inserted into the pin portion insertion depth is the shoulder portion volume. 1 ≦ discharge base material volume / shoulder portion volume ≦ 2.

  According to a fourth aspect of the present invention, in the friction stir welding method according to any one of the first to third aspects, the pin portion reaches a boundary surface of the stacked members to be joined at the pin portion insertion depth. It is characterized by.

  The invention of the rotary tool for friction stir welding according to claim 5 that achieves the first object includes a pin portion that is coaxially projected from the bottom surface of the cylindrical shoulder portion along the axis, and is overlapped. While rotating the pin part while pressing the pin part to the joining point of the joining member, the to-be-joined member around the pin part is heated and softened by frictional heat, and the pin part is inserted to a preset pin part insertion depth. Friction stir welding in which the members to be joined near the joining point are agitated by the rotating pin portion, and the members to be joined are integrated at the joining point, and then the members to be joined are spot-joined at the joining point by drawing along the axis. In the rotary tool for use, the pin portion protruding length of the pin portion protruding from the shoulder is greater than the pin portion insertion depth.

  The friction stir welding rotary tool according to claim 6 is the friction stir welding rotary tool according to claim 5, wherein the member to be welded and the shoulder portion are inserted in accordance with the insertion of the pin portion into the pin portion insertion depth. When the volume of the base material extruded between the bottom surface is the discharge base material volume, and the volume between the joined member and the bottom surface of the shoulder portion at the time of inserting the pin portion into the pin portion insertion depth is the shoulder portion volume, It has the pin part which satisfy | fills the conditions of discharge | emission base material volume / shoulder part volume> = 1, and the bottom face of a shoulder part, It is characterized by the above-mentioned.

  The invention according to claim 7, which achieves the second object, is the rotary tool for friction stir welding according to claim 5, wherein the member to be joined and the shoulder portion are inserted in accordance with the insertion of the pin portion into the pin portion insertion depth. When the volume of the base material extruded between the bottom surface is the discharge base material volume, and the volume between the joined member and the bottom surface of the shoulder portion at the time of inserting the pin portion into the pin portion insertion depth is the shoulder portion volume, It has the pin part which satisfy | fills the conditions of 1 <discharge | emission base material volume / shoulder part volume <= 2, and the bottom face of a shoulder part, It is characterized by the above-mentioned.

  The invention according to claim 8 is the friction stir welding rotary tool according to any one of claims 5 to 7, wherein the pin portion is a boundary surface of the members to be joined that overlap each other at the pin portion insertion depth. It has the pin part protrusion length which reaches | attains.

  The invention according to claim 9 is the friction stir welding rotary tool according to any one of claims 5 to 8, wherein θ> 0 when a shoulder angle formed between a virtual plane perpendicular to the axis and the bottom surface is θ. It is characterized by °.

  According to the friction stir welding method of the first aspect of the present invention, the pin portion insertion depth to be inserted into the member to be joined in the friction stir welding is made smaller than the pin portion protrusion length of the pin portion protruding from the shoulder portion. As a result, the frictional heat between the pin portion and the member to be joined and the member to be joined around the pin portion by the frictional heat of the base material and the shoulder portion pushed between the member to be joined and the bottom surface of the shoulder as the pin portion is inserted. Even if the pin part is inserted to the pin part insertion depth after heat softening, the shoulder part of the rotary tool does not directly contact the member to be joined. Compared to the conventional friction stir welding method in which the members to be joined are integrated, the joining load required at the time of joining can be greatly reduced. Along with a significant reduction in the joining load, the load applied to the equipment at the time of joining, that is, the equipment load becomes extremely small, the equipment can be miniaturized, and the equipment cost, running cost and maintenance cost can be greatly reduced.

  According to the invention of claim 2, when the pin portion is inserted with respect to the discharge base material volume pushed out between the joined member and the bottom surface of the shoulder portion with the insertion of the pin portion into the pin portion insertion depth. By reducing the volume of the shoulder portion between the member to be joined and the bottom surface of the shoulder portion, the space between the member to be joined and the shoulder is filled by the base material pushed out by insertion of the pin portion, and discharging by inserting the pin portion The base material is pushed between the shoulder portion and the member to be joined, the stirring of the member to be joined is promoted, a plastic flow region is secured, and the joining strength is increased.

  According to invention of Claim 3, the discharge | emission base material volume extruded between the to-be-joined member and the bottom face of a shoulder part with insertion of the pin part to pin part insertion depth, and to-be-joined at the time of insertion of a pin part By setting the shoulder portion volume between the member and the bottom surface of the shoulder portion to 1 ≦ discharge base material volume / shoulder portion volume ≦ 2, in addition to the effect of the invention of claim 2, to the pin portion insertion depth As a result of the insertion of the pin portion, the base material pushed between the joined member and the bottom surface of the shoulder portion is prevented from flowing out from between the joined member and the shoulder portion, and burrs are generated. Decrease. By reducing the generation of burrs, it is possible to omit the burr processing work for removing the burrs, or to reduce the deburring work.

  According to invention of Claim 4, since it has the pin part insertion depth which reaches the boundary surface of the to-be-joined member with which the pin part was piled up, the stirring and plastic flow area between each to-be-joined member are ensured, and joining strength Will increase.

  According to invention of Claim 5, the pin part protrusion length of the pin part which protrudes from the shoulder part of a rotary tool is made larger than the pin part insertion depth. As a result, frictional heat between the base material and the shoulder portion pushed out between the pin portion and the member to be joined and between the member to be joined and the bottom surface of the shoulder portion with the insertion of the pin portion causes the covering around the pin portion. Even if the joining member is heated and softened and the pin part is inserted to the pin part insertion depth, the shoulder part of the rotary tool does not directly contact the member to be joined. The load can be greatly reduced. By reducing the joining load, the load applied to the equipment at the time of joining, that is, the equipment load becomes extremely small, the equipment can be downsized, and the equipment cost, running cost and maintenance cost can be greatly reduced.

  According to the invention of claim 6, when the pin portion is inserted with respect to the discharge base material volume pushed out between the joined member and the bottom surface of the shoulder portion with the insertion of the pin portion into the pin portion insertion depth. The bottom surface of the pin portion and the shoulder portion is set so as to reduce the shoulder portion volume between the joined member and the bottom surface of the shoulder portion. As a result, the base material extruded by inserting the pin portion fills the space between the member to be joined and the shoulder portion, the discharge base material by inserting the pin portion is pushed into the inside, and the stirring of the member to be joined is promoted to be plastic. A flow zone is secured, and the bonding strength increases.

  According to the invention of claim 7, by setting the bottom surface of the pin portion and the shoulder portion so that the discharge base material volume and the shoulder portion volume are 1 ≦ discharge base material volume / shoulder portion volume ≦ 2, In addition to the effect of the invention of Item 6, the base material pushed between the joined member and the bottom surface of the shoulder portion with the insertion of the pin portion into the pin portion insertion depth is between the joined member and the shoulder portion. Outflow to the outside is reduced, the generation of burrs is reduced, and the burr processing operation for removing burrs can be omitted or the deburring operation can be reduced.

  According to the invention of claim 8, since the pin portion has a pin portion insertion depth that reaches the boundary surface of the members to be joined, the stirring and the plastic flow region between the members to be joined are ensured and the joining strength is increased. .

  According to the invention of claim 9, by setting the shoulder angle θ to θ> 0 °, the space between the member to be joined and the shoulder portion is filled with the base material pushed out by the insertion of the pin portion. The discharged base material by insertion is pushed into the inside, the stirring of the members to be joined is promoted, the plastic flow region is secured, and the joining strength is increased.

  Embodiments of a friction stir welding method and a friction stir welding rotary tool according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a conceptual diagram showing a main part of the friction stir welding apparatus 1. The friction stir welding apparatus 1 includes a work receiving portion 2 having an upper receiving surface 2a, an induction motor that is disposed opposite to the work receiving surface 2a and that rotates the rotary tool 10 around an axis L extending in the vertical direction. And the rotary tool pushing means 4 such as a servo motor for moving the rotary tool 10 along the axis L in the vertical direction contacting and separating from the receiving surface 2a and applying a bonding load to the rotary tool 10. And.

  The rotary tool 10 has a cylindrical shape, and a cylindrical shoulder portion 11 is formed at the tip thereof, and a pin portion 21 that protrudes along the axis L from the center of the bottom surface 13 of the shoulder portion 11 is formed. As shown in the cross-sectional view of FIG. 2, the bottom surface 13 of the shoulder portion 11 is formed in an inverted conical shape so that the center is recessed toward the proximal end side, and the pin portion 21 extends from the most recessed center portion along the axis L. Protrudes in the direction.

  An angle θ formed by a virtual plane La perpendicular to the axis L and the bottom surface 13 in the annular corner portion 14 extending from the outer peripheral surface 12 and the bottom surface 13 of the shoulder portion 11 is a shoulder angle. A corner portion 14 extending from the outer peripheral surface 12 to the bottom surface 13 serving as the tip of the shoulder portion 11 is formed as a so-called shoulder R that smoothly continues in an arc shape. Further, a portion 15 where the bottom surface 13 and the pin portion 21 are connected also has a so-called corner R which is smoothly connected in an arc shape.

  The pin portion 21 has a cylindrical shape, and a helical screw portion 22 is formed on the outer peripheral surface 22 thereof. A tip 23 of the pin portion 21 protrudes from the corner portion 14 in the direction of the axis L, and from the corner portion 14. The protruding dimension to the tip 23 of the pin portion 21 is the pin portion protruding length x.

  The rotating tool 10 configured in this manner is lowered along the axis L by the rotating tool pushing means 4 while being rotated by the rotation driving means 3, and frictional heat due to the contact between the rotating pin portion 21 and the member 51 to be joined. The to-be-joined members 51 and 52 are heated and softened, and the pin portion 21 is inserted until the corner portion 14 of the shoulder portion 11 approaches the surface 51a of the to-be-joined member 51 as shown in FIG. The base material in the vicinity of the joining point P is agitated by the pin portion 21 that rotates while being inserted into the base 51, and this agitation forms a plastic flow region in the base material. The joined members 51 and 52 are integrated at the joining point P. Become. In FIG. 3, the pin portion insertion depth y is from the surface 51 a of the bonded member 51 to the tip 23 of the pin portion 21 of the rotary tool 10.

  Here, the pin portion insertion depth y of the pin portion 21 is preferably set so as to reach the member to be bonded 52 beyond the boundary surface 53 between the members to be bonded 51 and 52. When the pin portion insertion volume inserted into the joining members 51 and 52 is Vp, the base material extruded onto the surface 51a of the joined member 51 along the outer peripheral surface 22 of the pin portion 21 as the pin portion 21 is inserted. The volume, that is, the discharge base material volume is also Vp (pin portion insertion volume = discharge base material volume = Vp).

  As shown in FIG. 3, when the pin portion 21 is inserted until the corner portion 14 of the shoulder portion 11 approaches the surface 51a of the member 51 to be joined, that is, when the pin portion is inserted to the pin insertion depth y, the pin portion 21 is covered with the discharge base material volume Vp. The volume of the shoulder portion 11 is such that the volume surrounded by the joining member 51 and the bottom surface 13 of the shoulder portion 11, that is, the shoulder portion volume Vs is 1 or more, preferably 1 or more and 2 or less (1 ≦ Vp / Vs ≦ 2). The diameter D, the diameter d of the pin portion 21, the pin portion insertion depth y, the shoulder angle θ, etc. are set.

  Here, an example of the calculation method of the discharge | emission base material volume Vp and the shoulder part volume Vs is demonstrated based on FIG.

  FIG. 4 is a diagram schematically showing a state where the pin portion 21 corresponding to FIG. 3 is at the pin portion insertion depth y. The discharged base material volume Vp is expressed by the following equation.

Discharged base material volume Vp = cross-sectional area of pin portion 21 × pin portion insertion depth
= Π (d / 2) ² × y
On the other hand, as shown in FIG. 4, the volume of the virtual cone whose bottom surface is the shoulder diameter D and the vertex a reaches the axis L at the shoulder angle θ is Va, and the bottom surface is the diameter d of the pin portion 21 and the vertex a at the shoulder angle θ. Vb is the volume of the virtual cone that reaches the axis L, Vc is the volume of the pin portion 21 in the shoulder portion 11, and the virtual annular shape between the virtual plane formed by the corner portion 14 of the shoulder portion 11 and the surface 51a of the member 51 to be joined. If the body volume is Vd, the shoulder volume Vs is expressed by the following equation.

Shoulder part volume Vs = volume Va−volume Vb−volume Vc + volume Vd
Here, volume Va = {π / 3 (D / 2) ² × (D / 2) Tanθ}
Volume Vb = {π / 3 (d / 2) ² × (d / 2) Tanθ}
= Volume ^{Vc {(d / 2) 2} π × (D-d) / 2 × Tanθ)}
Volume Vd = {(D / 2) ² π− (d / 2) ² π} × (xy),
Shoulder volume Vs = {π / 3 (D / 2) ² × (D / 2) Tanθ} − {π / 3 (d / 2) ² × (d / 2) Tanθ} − {(d / 2) ² π × (D−d) / 2 × Tanθ)} + {(D / 2) ² π− (d / 2) ² π} × (xy)
(However, D: shoulder diameter, d: pin portion diameter, θ: shoulder angle, x: protrusion length, y: pin portion insertion depth)

  Here, since the diameter d of the pin portion 21 affects the stirring area, increasing the diameter d of the pin portion 21 increases the plastic flow region and increases the bonding strength. The expansion of the plastic flow region causes the member 51 to be lifted, and a gap is generated at the boundary surface 53 between the members 51 and 52, which causes variations in bonding strength. On the other hand, since the shoulder portion 11 has a function of pushing the discharged base material by inserting the pin portion 21 into the inside to promote stirring, the agitating region is expanded by increasing the diameter D of the shoulder portion 11, resulting in plastic flow. Although the area increases and a strong bonding strength can be obtained, it is required to increase the bonding load and the rotational driving force at the time of bonding. The shoulder angle θ is set so that when the base material discharged by inserting the pin portion 21 is pressed into the interior, the discharged base material is smoothly guided to the inner stirring portion along the bottom surface 13, θ> It is set to 0 °, for example, 15 to 30 °. Further, if the shoulder R formed on the corner portion 14 of the shoulder portion 11 is an excessively acute angle, stress concentrates on the portion, causing cracks and the like. On the other hand, if the shoulder R and the corner R are increased, the pin portion Since the so-called escape that the base material discharged by inserting 21 flows out to the outside of the shoulder portion 11 easily occurs, for example, 0.2 to 0.4 mm is set. The diameter D of the shoulder portion 11, the diameter d of the pin portion 21, the shoulder angle θ, the shoulder R, and the corner R are preferably set based on experiments, simulations, and the like.

  FIG. 5 is a diagram illustrating a friction stir welding method. First, as shown in FIG. 1, on the workpiece receiving surface 2a of the workpiece receiving portion 2 of the friction stir welding apparatus 1 with the joining point P of the two members 51 and 52 made of an aluminum alloy plate aligned with the axis L. In this state, the members to be joined 51 and 52 are clamped to the workpiece receiver 2 by a clamping device (not shown).

  Then, as shown in FIG. 5A, the screw formed on the outer periphery 23 of the pin portion 21 by the rotation driving means 3 such as an induction motor at the raised position where the rotation tool 10 is separated from the member 51 to be joined. In the direction opposite to the spiral direction of the part 22, it is rotated at a high speed of, for example, about 800 to 1500 rpm.

  Next, the rotary tool push means 4 lowers the rotary tool 10 along the axis L. 5B, when the tip 23 of the pin portion 21 of the rotary tool 10 reaches and comes into contact with the member to be joined 51, the member to be joined is caused by frictional heat between the rotating pin portion 21 and the member to be joined 51. 51 and 52 are heated, and the vicinity of the joining point P of the members to be joined 51 and 52 is softened.

  By further pressing by the rotating tool pressing means 4, the rotating pin portion 21 is inserted into the softened members 51 and 52, and the tip 23 of the pin portion 21 is bonded as shown in FIG. 5C. Up to a preset pin insertion depth y that reaches the member to be joined 52 beyond the boundary surface 53 between the members 51 and 52, that is, the corner portion 14 of the shoulder portion 11 approaches the surface 51a of the member 51 to be joined. When reaching a position where a slight gap A is formed between the surface 51a of the joining member 51 and the corner portion 14, the insertion of the pin portion 21 by the rotary tool pushing means 4 is stopped.

  When the pin 21 is inserted into the members 51 and 52 to be joined, the pin 21 is inserted into the members 51 and 52 that are heated and softened by frictional heat between the pin 21 and the members 51 and 52. The softened base material is extruded along the threaded portion 22, that is, the outer peripheral surface of the pin portion 21 and filled between the bonded member 51 and the bottom surface 13 of the shoulder portion 11, and the bottom surface 13 is inclined at the shoulder angle θ. Are guided to the corner 14 side and pushed into the joined member 51 side, that is, the inner side. At this time, the shoulder portion volume Vs formed between the joined member 51 and the bottom surface 13 of the shoulder portion 11 is set smaller than the discharged base material volume Vp pushed out with the insertion of the pin portion 21. As shown in FIG. 5C, the surplus base material, that is, the surplus wall, flows out from the slight gap A between the surface 51 a of the bonded member 51 and the corner portion 14.

  Softened by being heated by frictional heat between the base material filled between the bonded member 51 and the bottom surface 13 of the shoulder portion 11 and the bottom surface 13 of the shoulder portion 11, and frictional heat between the bottom surface 13 and the bonded member 51. When the pin portion 21 is inserted into the joined members 51 and 52 to the pin insertion depth y, the plastic flow is induced, and the rotating pin portion 21 agitates the vicinity of the joining point P. Here, the volume surrounded by the bonded member 51 and the bottom surface 13 of the shoulder portion 11, that is, the shoulder portion volume Vs is in the range of 1/2 to 1 with respect to the discharge base material volume Vp (that is, 1 ≦ Vp / Vs ≦ 2), the base material pushed out by insertion of the pin portion 21 is pushed into the inner side by the bottom surface 13 of the shoulder portion 11, so that the base material around the pin portion 21 becomes dense and is joined. The members 51 and 52 are heated and stirred to promote plastic flow.

  In this way, the plastic flow region of the base material agitated in the vicinity of the joining point P by rotating the rotary tool 10 with the tip 23 of the pin portion 21 exceeding the boundary surface 53 between the members 51 and 52 to be joined. Are formed, and the joined members 51 and 52 are integrated at the joining point P. After stirring for a predetermined time, the rotary tool 10 is pulled out from the members 51 and 52 as shown in FIG. When the pin portion 21 is pulled out, the base material that has been plastically flowed is cured, and the joined members 51 and 52 are joined at the joining point P.

  FIG. 6 is a view showing a cross section of the joining points of the joined members 51 and 52 after joining. As shown by the hatched lines in FIG. 6, an annular shape is formed so as to surround the recess 54 on the surface 51 a side of the member 51 to be joined by the periphery of the recess 54 in which the pin portion 21 is inserted and the bottom surface 14 of the shoulder portion 11. The joined members 51 and 52 are integrated by plastic flow in the portion 55, and the surface 52a of the joined member 52 into which the pin portion 21 is not inserted is maintained in a smooth surface shape.

  In addition, burrs 56 are generated along the outer periphery of the annular portion 55. The burrs 56 are formed between the joined member 51 and the bottom surface 13 of the shoulder portion 11 with respect to the discharged base material volume Vp that is pushed out as the pin portion 21 is inserted. By setting the volume difference of the shoulder portion volume Vs formed therebetween to be small, it is possible to reduce the excess wall flowing out from the gap A between the surface 51a and the corner portion 14 of the member 51 to be joined. Therefore, by reducing the burrs 56, the quality of the joined members 51 and 52 joined can be improved, and the deburring process in the subsequent process can be omitted or the deburring work in the deburring process can be greatly reduced.

  FIG. 7 is a diagram illustrating a relationship between the volume ratio of the discharged base material volume Vp to the shoulder portion volume Vs (discharged base material volume Vp / shoulder portion volume Vs) and bonding strength. The conventional rotary tool in FIG. 7 has a bonding strength obtained by a conventional friction stir welding method using a rotary tool having a shoulder portion and a pin portion having the same diameter as the shoulder portion and the pin portion of the rotary tool in the present embodiment.

  From FIG. 7, the bonding strength of the members to be bonded 51 and 52 is correlated with the volume ratio of the shoulder volume Vs and the discharge base material volume Vp. If the discharge base material volume Vp / shoulder volume Vs is less than 1, the bonding strength is extremely high. It can be confirmed that the strength decreases, and conversely, when the discharge base material volume Vp / shoulder volume Vs is 1 or more, the joining strength can be secured and the joining strength is substantially constant.

  FIG. 8 is a diagram showing a relationship between the volume ratio of the discharged base material volume Vp to the shoulder portion volume Vs (discharged base material volume Vp / shoulder portion volume Vs) and the joining load. The conventional rotating tool in FIG. 8 is a joining load in a conventional friction stir welding method using a rotating tool having the same diameter as the shoulder portion and the same diameter as the pin portion of the rotating tool in the present embodiment.

  FIG. 8 shows that the bonding load is correlated with the volume ratio of the shoulder portion volume Vs and the discharged base material volume Vp, and it can be confirmed that the bonding load increases as the discharged base material volume Vp / shoulder portion volume Vs increases. .

  On the other hand, as the discharge base material volume Vp / shoulder portion volume Vs increases, the base material pushed out from the gap A between the corner portion 14 of the shoulder portion 11 of the rotary tool 10 and the member 51 to be joined increases and burrs are generated. Considering that many occur, by setting the volume ratio of the discharged base material volume Vp to the shoulder portion volume Vs within the range of 1 to 2 (1 ≦ discharged base material volume Vp / shoulder portion volume Vs ≦ 2). Thus, it can be confirmed that the bonding strength can be ensured while reducing the bonding load and the occurrence of burrs can be suppressed, and a good friction stir welding can be obtained.

  According to the friction stir welding method of the present invention, the joining load required for the friction stir welding is greatly reduced, the load applied to the equipment at the time of joining, that is, the equipment load becomes extremely small, and the equipment can be downsized. Cost, running costs and maintenance costs can be greatly reduced.

  Specifically, for example, a friction stir welding apparatus can be mounted on an articulated robot as equipment, and the friction stir welding apparatus can be supported by a balancer so that an operator can hold the friction stir welding apparatus and spot it. Joining work can be performed.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. For example, although the screw part 22 was formed in the outer periphery of the pin part 21 of the rotary tool 10 in the said embodiment, when sufficient plastic flow is securable, a screw part can be abbreviate | omitted and the simplification of a shape can be achieved. . Moreover, in the said embodiment, although the plastic flow was formed by rotating for a set time in the state which inserted the pin part 21 to the pin part insertion depth y, it is set time in the state inserted to this pin part insertion depth y. The rotating holding time can be appropriately set in consideration of the bonding strength and the like.

It is a conceptual diagram which shows the principal part of the friction stir welding apparatus which concerns on embodiment. It is principal part sectional drawing of a rotation tool. It is a figure which shows the insertion state of a pin part. It is a figure explaining calculation of a discharge base material volume and a shoulder part volume. It is a figure which shows the friction stir welding method. It is a figure which shows the cross section of the joining point of the to-be-joined member after joining. It is a figure which shows the relationship between the volume ratio of the discharge | emission base material volume with respect to a shoulder part volume, and joining strength. It is a figure which shows the relationship between the volume ratio of the discharge | emission base material volume with respect to a shoulder part volume, and joining load. It is a figure which shows the front-end | tip of the rotary tool for friction stir welding concerning a prior art example. It is explanatory drawing of a friction stir welding method same as the above. It is explanatory drawing of a friction stir welding method same as the above. It is a figure which shows the cross section of the joining point of the to-be-joined member after joining same as the above. It is a figure which shows transition of the joining load in a friction stir welding method same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Friction stir welding apparatus 3 Rotation drive means 4 Rotation tool pushing means 10 Rotation tool 11 Shoulder part 12 Outer peripheral surface 13 Bottom face 14 Corner part 21 Pin part 22 Screw part 51, 52 Joined member 53 Boundary surface L Axis line P Joint point x Protrusion length y Pin insertion depth Vp Pin insertion volume (discharge base material volume)
Vs Shoulder volume θ Shoulder angle

Claims (9)

It has a rotary tool with a pin part that protrudes along the axis on the same axis from the bottom of the cylindrical shoulder part, and presses the pin part against the joint point of the stacked members to be joined while rotating the rotary tool around the axis The above-mentioned to-be-joined member around the pin part is heated and softened by friction heat, and the pin part is inserted to a preset pin part insertion depth, and the to-be-joined member near the joining point is stirred by the rotating pin part. In the friction stir welding method in which each member to be joined is integrated at the joining point, and then the member to be joined is spot-joined at the joining point by pulling out along the axis.
The friction stir welding method, wherein the pin portion insertion depth is smaller than a pin portion protruding length of the pin portion protruding from the shoulder portion. The volume of the base material pushed between the member to be joined and the bottom surface of the shoulder portion with the insertion of the pin portion into the pin portion insertion depth is the discharge base material volume, and the insertion of the pin portion into the pin portion insertion depth When the volume between the joined member and the bottom surface of the shoulder portion at the time is the shoulder portion volume,
Discharged base material volume / shoulder volume ≧ 1
The friction stir welding method according to claim 1, wherein: The volume of the base material pushed between the member to be joined and the bottom surface of the shoulder portion with the insertion of the pin portion into the pin portion insertion depth is the discharge base material volume, and the insertion of the pin portion into the pin portion insertion depth When the volume between the joined member and the bottom surface of the shoulder portion at the time is the shoulder portion volume,
1 ≦ Volume of discharged base material / Volume of shoulder portion ≦ 2
The friction stir welding method according to claim 1, wherein:   The friction stir welding method according to any one of claims 1 to 3, wherein the pin portion reaches a boundary surface of the overlapped members to be joined at the pin portion insertion depth. It is provided with a pin portion that projects coaxially from the bottom surface of the cylindrical shoulder portion along the axis, and rotates around the axis while pressing the pin portion against the joining point of the overlapped members, and the pin portion is caused by frictional heat. The surrounding members to be joined are heated and softened to insert the pin portion to a preset pin portion insertion depth, and at the rotating pin portion, the members to be joined in the vicinity of the joining point are agitated to join the members to be joined together. In the rotary tool for friction stir welding that is pulled out along the axis and spot-bonded to-be-joined members at the joint points,
A rotating tool for friction stir welding, wherein a pin portion protruding length of a pin portion protruding from the shoulder portion is larger than the pin portion insertion depth. The volume of the base material pushed between the member to be joined and the bottom surface of the shoulder portion with the insertion of the pin portion into the pin portion insertion depth is the discharge base material volume, and the insertion of the pin portion into the pin portion insertion depth When the volume between the joined member and the bottom surface of the shoulder portion at the time is the shoulder portion volume,
Discharged base material volume / shoulder volume ≧ 1
The rotary tool for friction stir welding according to claim 5, comprising a pin portion and a bottom surface of a shoulder portion that satisfy the above condition. The volume of the base material pushed between the member to be joined and the bottom surface of the shoulder portion with the insertion of the pin portion into the pin portion insertion depth is the discharge base material volume, and the insertion of the pin portion into the pin portion insertion depth When the volume between the joined member and the bottom surface of the shoulder portion at the time is the shoulder portion volume,
1 ≦ Volume of discharged base material / Volume of shoulder portion ≦ 2
The rotary tool for friction stir welding according to claim 5, comprising a pin portion and a bottom surface of a shoulder portion that satisfy the above condition.   The friction according to any one of claims 5 to 7, wherein the pin portion has a pin portion protruding length that reaches a boundary surface of the overlapped members to be joined at the pin portion insertion depth. Rotating tool for stir welding. The rotary tool for friction stir welding according to any one of claims 5 to 8, wherein θ> 0 °, where θ is a shoulder angle between a virtual plane orthogonal to the axis and the bottom surface.

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