JP2009269077A - Friction stir welding method and friction stir welding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably obtain the predetermined welding quality regarding the welding strength and the bead appearance or the like irrespective of dimensional errors of a weld part when executing the friction stir welding by butting edges of dissimilar metal materials having different hardness. <P>SOLUTION: When executing the friction stir welding by moving a welding tool 10 along the welding line W, the welding tool 10 is moved along the welding line W while adjusting the X-direction position Lx of the welding tool so that the X-direction load Fx substantially perpendicular to the welding line W is the predetermined target load (the optimum load fxbest). Thus, the excellent welding quality according to the target load is stably obtained irrespective of any difference in the materials (hardness or the like) of a pair of welded members 42, 44 and dimensional errors of a weld part indicated by the welding line W. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a friction stir welding method, and more particularly to a technique for stably obtaining predetermined joining quality when friction stir welding is performed by abutting edges of dissimilar metal materials having different hardnesses.

  While rotating the joining tool with the agitating protrusion protruding at the tip about the axis S, the agitating protrusion is pressed onto the joining line W where the edges of the pair of members to be joined are abutted with each other. The member to be joined is softened by frictional heat so that the stirring protrusion is immersed, and the joining tool is relatively moved along the joining line W so that the vicinity of the edges of the pair of members to be joined A friction stir welding method (FSW: Friction Stir Welding) in which stirring is performed with a stirring protrusion and mixed together is proposed as a method for joining a metal plate such as an aluminum alloy (see Patent Document 1). Specifically, it is used for joining metal plates that make up car bodies such as railway cars and automobiles, and is made by softening the metals below the melting point and joining them together, so laser welding and spot welding. As described above, there are advantages such as lower processing temperature and smaller deformation and distortion compared to melting and joining metals.

  FIG. 7 is a diagram for explaining an example of such a friction stir welding method, where (a) is a perspective view when the edges of a pair of members 30 and 32 are abutted and friction stir welding is performed by the welding tool 10; (b) is an enlarged view of the section VIIB-VIIB in (a). The joining tool 10 is integrally provided with a cylindrical shaft portion 12 and a small-diameter stirring protrusion 14 that is provided concentrically with the shaft portion 12 at the center of the tip of the shaft portion 12. The stirring protrusion 14 has a substantially cylindrical shape (in the figure, a taper shape with a slightly smaller diameter toward the tip side), and the outer peripheral surface thereof is provided with irregularities such as a screw that is reversely twisted in the tool rotation direction. In addition, the tip surface (projection tip surface) 18 has a partial spherical shape. In addition, the annular portion located on the outer peripheral side of the stirring protrusion 14 on the tip surface of the shaft portion 12 is provided with a recess 20 that gradually becomes deeper from the outer periphery toward the stirring protrusion 14. It has been.

The pair of members to be joined 30 and 32 are positioned and placed on the flat support base 34 in a state in which their edges are abutted so as to contact each other. The joining line W is friction stir welded by the joining tool 10. That is, when the welding tool 10 is pressed on the welding line W while being rotated clockwise around the axis S, the vicinity of the edges of the members 30 and 32 to be welded is softened by frictional heat, and the stirring protrusion 14 Is immersed in the softened portion 36, the softened portion 36 is stirred and mixed by the stirring protrusion 14. In this state, when the welding tool 10 is relatively moved along the joining line W as indicated by the arrow A, the softened portion 36 continuously moves along the joining line W, and the softened portion 36 that is the movement source. Are sequentially cooled and hardened, so that both the joined members 30 and 32 are sequentially and integrally joined over the entire length of the joining line W. Reference numeral 38 in FIG. 7A denotes a stir joint where the softened portion 36 is cooled and hardened.
JP 2001-198683 A

  Such a friction stir welding method has been conventionally used when a pair of members to be joined is made of the same metal plate, but a pair of members made of different metals having different hardnesses. When trying to join, a problem has been found that the joining quality such as joining strength and bead appearance greatly changes depending on the positional relationship between the axis S of the tool and the joining line W. That is, according to the experiments and researches of the present inventors, as shown in FIGS. 8A to 8C, when the pair of members 30 and 32 are made of the same metal material (for example, aluminum alloy). The friction stir welding is possible even when the axis S of the welding tool 10 is shifted to the left and right of the welding line W, and substantially the same quality can be stably obtained with respect to the bonding quality such as the bonding strength and the bead appearance. As shown in FIGS. 8D to 8F, in the case of dissimilar metals, that is, when one member 30 is a steel material and the other member 32 is an aluminum alloy, the axis of the joining tool 10 is used. Depending on the positional relationship between S and the joining line W, the joining quality is greatly changed, for example, a gap (nest) is formed in the joined portion due to wear of the stirring protrusion 14 or the joining strength is lowered. There were cases where it was impossible. Specifically, as shown in FIG. 8 (e), the shaft center S of the welding tool 10 is connected to the joining line W so that the stirring protrusion 14 slightly enters the member to be joined (steel material) 30 side. Can also be joined if they are shifted to the member to be joined (aluminum alloy) 32 side, but as shown in (d) and (f), the stirring protrusion 14 is directed to the member to be joined (steel material) 30 side. When the intrusion dimension is increased, a large offset load is generated in the welding tool 10 and the agitation protrusion 14 is abruptly worn.

  Therefore, when the pair of members to be joined 30 and 32 are made of different metals, the intrusion dimension of the stirring protrusion 14 with respect to the hard member to be joined (steel material) 30 is small as shown in FIG. In this way, the friction stir welding may be performed by shifting the axis S of the welding tool 10 to the opposite side of the welding line W, that is, the member to be joined (aluminum alloy) 32, but the actual member 30 to be joined. 32, that is, the joining line W is not always designed and has an error, and it is difficult to control the position of the joining tool 10 by detecting the joining line W, so that a substantially constant joining quality is stable. It is difficult to get. 8 (a) to 8 (f) are all cross-sectional views corresponding to FIG. 7 (b), but are particularly for explaining the positional relationship between the shaft center S and the joining line W. FIG. FIG. 5 is a schematic view in which the softened portion 36 is omitted and the shape of each portion is simplified.

  The present invention has been made against the background of the above circumstances, and the purpose of the present invention is to match the edges of dissimilar metal materials with different hardnesses when performing friction stir welding, regardless of dimensional errors at the joints. The object is to stably obtain a predetermined bonding quality relating to bonding strength, bead appearance, and the like.

  In order to achieve such an object, according to the first aspect of the present invention, the edges of the pair of members to be joined are abutted against each other while the joining tool having a protruding protrusion for stirring at the tip is rotated about the axis S. Pressing the stirring protrusion on the joining line W, softening the member to be joined by frictional heat, immersing the stirring protrusion, and moving the joining tool relative to the joining line W Thus, in the friction stir welding method in which the vicinity of the edges of the pair of members to be joined is agitated and mixed by the stirring protrusions and integrally joined together, (a) the pair of members to be joined are hardened to each other. (B) When performing the friction stir welding by relatively moving the joining tool along the joining line W, the X-direction load Fx intersecting the joining line W Will be a predetermined target load In, and wherein the relatively moving along the joint line W while adjusting the X-direction position of the welding.

  The second invention is the friction stir welding method according to the first invention, wherein (a) the relationship between the X-direction position Lx of the welding tool relative to the welding line W and the X-direction load Fx acting on the welding tool. And a data storage means in which the optimum tool position lxbest set as the X-direction position Lx for obtaining an appropriate joining state is stored in advance, and (b) the joining tool is connected to the joining line. A load detecting step of detecting an actual X-direction load Fx when performing friction stir welding by relatively moving along W, and (c) an X-direction corresponding to the X-direction load Fx based on the load characteristic data A position calculating step for calculating the position Lx, and (d) a position deviation calculating step for calculating a position deviation Mx between the X-direction position Lx and the optimum tool position lxbest, and (e) only the position deviation Mx. in front Characterized in that for displacing the X-direction position Lx of welding.

  In the third aspect of the present invention, while the welding tool having a stirring protrusion projecting at the tip is driven to rotate about the axis S, the edge of the pair of members to be joined is placed on the joining line W where the edges of each other are butted together. The pair of members to be joined is pressed by pressing the protrusions, softening the member to be joined by frictional heat and immersing the stirring protrusion, and relatively moving the joining tool along the joining line W. In the friction stir welding apparatus that stirs and mixes the vicinity of the edges of the edges with a stirring protrusion and integrally joins them, (a) the pair of members to be joined are made of different metals having different hardnesses. (B) a load detecting means for detecting an X-direction load Fx that intersects the joining line W when performing the friction stir welding by relatively moving the joining tool along the joining line W; (c) Detected by the load detection means Wherein as X direction load Fx becomes the target load a predetermined, characterized by having a a X-direction position adjusting means for adjusting the X-direction position of the bonding tool.

  4th invention is the friction stir welding apparatus of 3rd invention, (a) The relationship between the X direction position Lx of the said welding tool on the basis of the said welding line W, and the said X direction load Fx which acts on the said welding tool And a data storage means in which an optimum tool position lxbest set as the X-direction position Lx at which an appropriate joining state is obtained is stored in advance, and (b) the X-direction position adjusting means includes: (B-1) An X-direction position Lx corresponding to an actual X-direction load Fx detected by the load detecting means when performing friction stir welding by relatively moving the joining tool along the joining line W. (B-2) position deviation calculating means for calculating a position deviation Mx between the X-direction position Lx and the optimum tool position lxbest, b-3) Only the position deviation Mx, characterized in that for displacing the X-direction position Lx of the bonding tool.

  The fifth invention is the friction stir welding apparatus according to the third or fourth invention, wherein when the friction stir welding is performed according to actual welding conditions while the welding tool is relatively moved along the welding line W, the welding line W The X-direction position Lx of the joining tool with respect to the welding tool is changed, and the X-direction load Fx acting on the joining tool is detected to express the relationship between the X-direction position Lx and the X-direction load Fx. It has the data acquisition means which acquires load characteristic data, It is characterized by the above-mentioned.

  According to the friction stir welding method of the first invention, when the friction stir welding is performed by relatively moving the welding tool along the welding line W, the X-direction load Fx intersecting the welding line W is determined in advance. Since the relative movement is performed along the joining line W while adjusting the position of the joining tool in the X direction so that the target load becomes the target load, the difference in the material (hardness, etc.) of the pair of joined members and the joining line W Regardless of the dimensional error of the joint portion to be expressed, excellent joint quality according to the target load can be stably obtained. That is, the X-direction load Fx changes according to the positional relationship between the axis S of the joining tool and the joining line W. If the X-direction load Fx is substantially constant, the position between the axis S of the joining tool and the joining line W The relationship is also maintained substantially constant, and a substantially constant joining quality can be stably obtained. In particular, the X-direction load Fx can be detected easily and with high accuracy as compared with the case where the actual joining line W, that is, the butting position of a pair of members to be joined, is detected. Thus, the friction stir welding obtained can be carried out easily.

  Further, since the position in the X direction is adjusted so that the X-direction load Fx becomes the target load in this way, the X-direction load Fx is prevented from becoming excessively larger than the target load, and agitation due to uneven load is prevented. Wear of the projection is suppressed and the life of the joining tool is improved.

  In the second invention, when the friction stir welding is performed by relatively moving the welding tool along the welding line W, the actual X-direction load Fx is detected, and the X-direction load is determined based on preset load characteristic data. An X-direction position Lx corresponding to Fx is calculated, a position deviation Mx between the X-direction position Lx and a predetermined optimum tool position lxbest is obtained, and the X-direction position Lx of the joining tool is displaced by the position deviation Mx. Therefore, for example, the X-direction position Lx is quickly displaced to the optimum tool position lxbest, compared to the case where the X-direction position Lx is feedback-controlled so that the X-direction load Fx matches the target load, and the joining tool is optimal. It becomes possible to hold the tool position lxbest well, and the joining quality is further stabilized.

  The optimum tool position lxbest corresponds to the target load of the X direction load Fx, and the control for displacing the X direction position Lx of the joining tool to the optimum tool position lxbest is performed so that the X direction load Fx becomes the target load. This is substantially the same as adjusting the X-direction position Lx. In other words, in the load characteristic data representing the relationship between the X direction position Lx and the X direction load Fx of the joining tool, the X direction load Fx corresponding to the optimum tool position lxbest is the target load.

  The friction stir welding apparatus according to the third aspect of the invention relates to an apparatus that can suitably carry out the friction stir welding method according to the first aspect of the invention, and substantially the same effects as those of the first invention can be obtained. The fourth invention relates to an apparatus that can suitably carry out the friction stir welding method of the second invention, and substantially the same operational effects as the second invention can be obtained.

  The fifth aspect of the invention changes the X-direction position Lx of the joining tool with respect to the joining line W, detects the X-direction load Fx acting on the joining tool, and detects the X-direction position Lx and the X-direction load. Since data acquisition means for acquiring load characteristic data representing the relationship with Fx is provided, even when friction stir welding is performed under various joining conditions such as different materials of the members to be joined, the actual joining conditions preliminarily By performing friction stir welding, load characteristic data according to actual welding conditions can be easily obtained, and by examining the bonding quality of each part on the bonding line W, the target load and the best load quality can be obtained. The optimum tool position lxbest and the like can be easily set.

  The friction stir welding method and the friction stir welding apparatus of the present invention are preferably used when, for example, an aluminum alloy and a steel material are friction stir welded as a pair of members to be joined, but also when other dissimilar metals are joined. It can be applied as well. As a material of the joining tool, it is necessary to employ a material having higher hardness and superior heat resistance than the member to be joined, and a cemented carbide is preferably used, but is appropriately determined according to the material of the member to be joined.

  As the joining tool, for example, as in the joining tool 10 of FIG. 7, the tip side has a slightly smaller diameter tapered or cylindrical stirring protrusion, and the outer peripheral surface of the stirring protrusion has, for example, Concavities and convexities, such as external threads that are counter-twisted with the tool rotation direction, are provided, and the tip surface of the stirring projection has a partial spherical shape, and is the tip surface of the shaft portion and is more outer than the stirring projection. The annular portion located on the side is preferably provided with a recess that gradually becomes deeper from the outer peripheral edge toward the stirring protrusion, but a prism-shaped stirring protrusion is employed. Various modes are possible, such as providing irregularities other than the male screw and making the tip surface of the shaft portion (the outer peripheral side of the stirring projection) a flat surface.

  The joining line W in which the edges of the pair of members to be joined are abutted is preferably a straight line in relation to relatively move the joining tool along the joining line W. For example, the direction perpendicular to the straight line is Although it is set as the X direction, it is also possible to adopt a joining line W such as a broken line shape connecting a plurality of straight lines or a continuously curved curve shape, that is, an edge shape. In the case of a polygonal line, for example, the X direction, the target load, the optimum tool position lxbest, etc. may be set separately by dividing into a plurality of straight line parts. Various modes are possible, such as dividing the movement path into a large number of straight line portions and separately setting the X direction, the target load, the optimum tool position lxbest, and the like for each straight line portion. Note that the X direction of the X direction load Fx and the X direction position Lx is preferably a direction perpendicular to the joining line W, but a direction intersecting at a predetermined angle other than a right angle may be the X direction.

  In the second and fourth inventions, the X-direction position Lx corresponding to the actual X-direction load Fx is calculated based on preset load characteristic data, and the X-direction position Lx and a predetermined optimum tool position are calculated. The position deviation Mx with respect to lxbest is obtained, and the X-direction position Lx of the welding tool is displaced by the position deviation Mx. However, when the first invention and the third invention are implemented, the X-direction load Fx matches the target load. Various modes are possible, such as feedback control of the X-direction position Lx according to the deviation. When the relative movement of the welding tool along the welding line W is controlled by NC control or the like according to predetermined movement path data, the movement path data itself or the learning correction value can be rewritten by the position deviation Mx or the like. It is also possible to employ known learning control.

  For example, when the joining line W is a straight line, the data acquisition means of the fifth aspect of the invention is a small predetermined with respect to the joining line W so that the stirring protrusion moves from one side to the other across the joining line W. The actual welding conditions at the time of friction stir welding along the welding line W by relatively moving the welding tool along a straight data acquisition line determined to intersect at an angle (for example, 10 ° or less) Under substantially the same conditions, the load characteristic data can be easily obtained by continuously changing the X-direction position Lx of the welding tool with the welding line W as a reference. However, the relationship between the X direction position Lx and the X direction load Fx is expressed by changing the X direction position Lx stepwise or by separately performing a plurality of friction stir weldings with different X direction positions Lx. Various aspects are possible, such as obtaining the load characteristic data and determining the target load by examining the joining state of the stirring joint.

  According to the experiments by the inventors, the rotation direction and the relative movement direction of the welding tool when the friction stir welding is performed along the joining line W of the pair of members to be joined are up-cut with respect to the hard-side members to be joined. It is desirable to set to stir. For example, as shown in FIG. 7, when the friction stir welding is performed by moving the welding tool 10 in the clockwise direction of the axis S as viewed from above and moving the welding tool 10 to the opposite side as indicated by an arrow A, the left workpiece is joined. The member 30 is made of a relatively hard metal material such as a steel material, and the right joined member 32 is made of a relatively soft metal material such as an aluminum alloy. However, depending on the joining conditions such as the rotational speed, the moving speed (feeding speed), the material of both the joined members, etc., it is also possible to perform the friction stir welding by stirring the hard side joined member by down-cutting. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic perspective view when a pair of members to be joined 42 and 44 are friction stir welded using the welding tool 10 by a friction stir welding apparatus 40 according to an embodiment of the present invention. Friction stir welding is performed in the same manner as in the example, but one member 40 is a relatively hard metal material such as a steel material, while the other member 42 is a comparison of aluminum alloy or the like. Soft metal material. The joining tool 10 is rotationally driven around the axis O by a rotational drive device 50 such as an electric motor, and is moved by the three-dimensional movement device 52 in the X, Y, and Z axial directions according to predetermined movement path data. In the state in which the stirring protrusion 14 is immersed in the members to be joined 42 and 44 by a predetermined dimension by NC control by the electronic control unit 54, as shown by the arrow A, the joining line W Is moved along.

  The joining line W is substantially straight, and the pair of members to be joined 42 and 44 are placed on the support base 34 in a posture that is substantially horizontal, that is, substantially perpendicular to the Z-axis direction of the three-dimensional movement device 52, and The joining line W is positioned in a posture that substantially coincides with the Y-axis direction, and the arrow A that is the moving direction of the joining tool 10 substantially coincides with the Y-axis direction. Further, the rotational direction and the moving direction A of the welding tool 10 are determined so as to stir up-cut with respect to the hard-side member 42, and the welding tool 10 is rotated clockwise around the axis S as viewed from above. While being rotationally driven, it is moved along the joining line W in the right back direction in the figure. The joining tool 10 is made of a material having higher hardness and heat resistance than the hard-side member to be joined 42, and is composed of K type cemented carbide in this embodiment.

  On the other hand, the friction stir welding apparatus 40 of the present embodiment is configured so that the stirring protrusion 14 of the welding tool 10 is immersed in the members 42 and 44 to be moved in the moving direction A and friction stir welding is performed along the welding line W. , A load sensor 56 such as a dynamometer that detects an X-direction load Fx acting in the X-axis direction substantially perpendicular to the joining line W is provided, and a signal representing the X-direction load Fx is transmitted to the electronic device. It supplies to the control apparatus 54. This load sensor 56 corresponds to a load detection means.

  The electronic control unit 54 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. A predetermined signal is used in accordance with a program stored in the ROM in advance using the temporary storage function of the RAM. By performing the processing, each function shown in the block diagram of FIG. 2 is executed. In FIG. 2, the three-dimensional position control means 66 moves the welding tool 10 by NC control in accordance with movement path data set in advance for performing friction stir welding along the welding line W. The correcting means 64 is based on the actual X-direction load Fx supplied from the load sensor 56, the load characteristic data stored in advance in the data storage means 60, and the optimum tool position lxbest. The X-direction position Lx controlled by the three-dimensional position control means 66 is corrected so that the direction position Lx substantially coincides with the optimum tool position lxbest. The X direction position correcting means 64 corresponds to the X direction position adjusting means.

  As shown in FIG. 3A, the load characteristic data is acquired in advance by the data acquisition means 62 in relation to the X-direction position Lx of the welding tool 10 and the X-direction load Fx, and is configured by a RAM or the like. Stored in the data storage means 60. For example, as shown in FIG. 3 (b), the data acquisition means 62 is connected to the joining line W so that the stirring protrusion 14 of the joining tool 10 moves from one to the other across the straight joining line W. While the welding tool 10 is moved along a straight data acquisition line Wd determined to intersect with a small predetermined angle (for example, 10 ° or less), the welding conditions such as the rotation speed n and the movement speed f are actually set. The friction characteristic welding is performed in advance (preliminary) under the same conditions as when the friction stir welding is performed, and the load characteristic data is acquired by continuously reading the X-direction load Fx detected by the load sensor 56. The X-direction position Lx is a position in the X-axis direction of the welding tool 10 with respect to the welding line W. In this embodiment, the agitation protrusion 14 is an intrusion dimension that penetrates into the hard member 42 side. The tool 10 is continuously changed by being linearly moved along the data acquisition line Wd. This load characteristic data is stored in the data storage means 60 by a data map, an arithmetic expression, or the like.

Further, the optimum tool position lxbest stored in advance in the data storage means 60 is the X-direction position Lx at which the best joining quality is obtained, and when the load characteristic data is obtained by the data obtaining means 62, the data acquisition line Wd is obtained. The optimum point Q at which the best joining quality is obtained is obtained by examining the joining states of the stir welded portions 38 that are friction stir welded along, for example, the joining strength, the presence or absence of voids, and the bead shape. The X direction position Lx of Q is input and set by the operator as the optimum tool position lxbest. Incidentally, as shown in FIG. 4, one member 42 is made of a steel material “S45C” (JIS symbol) and the other member 44 is an aluminum alloy “A6063” (JIS symbol). When the friction stir welding is performed under the following joining conditions, the optimum tool position lxbest is about 0.1 mm, and the stirring protrusion 14 has entered the steel material to be joined 42 side by 0.1 mm. The best joining quality was obtained when the friction stir welding was performed in a state where the remaining 3.9 mm was located on the aluminum alloy bonded member 44 side. Further, the X-direction load Fx when the friction stir welding was performed at the optimum tool position lxbest≈0.1 mm, that is, the optimum load fxbest (see FIG. 3A) was about 20 MPa.
(Joining conditions)
-Diameter dimension φ of the protrusion 14 for stirring: 4 mm
・ Immersion dimension a of the stirring protrusion 14: 4 mm
・ Rotation speed n of the welding tool 10: 4000 rpm
-Moving speed f of the welding tool 10: 1000 mm / min

  On the other hand, the X-direction position correction means 64 acquires the load characteristic data by the data acquisition means 62 and stores it in the data storage means 60, and after the optimum tool position lxbest is set, the welding tool 10 is actually set. When the agitating protrusion 14 is immersed in the members 42 and 44 to be joined on the joining line W and is moved along the joining line W while being rotationally driven around the axis S, the friction stir welding is performed as shown in FIG. Signal processing is performed according to the flowchart shown in FIG. Step S1 in this flowchart corresponds to a load detection process, step S2 corresponds to a position calculation process, and step S3 corresponds to a position deviation calculation process. Step S2 functions as a position calculation unit, and step S3 functions as a position deviation calculation unit.

  In step S1 of FIG. 5, a signal representing the X-direction load Fx is read from the load sensor 56. In step S2, the X-direction position Lx corresponding to the X-direction load Fx is read from the load characteristic data stored in the data storage means 60. calculate. FIG. 6 shows an example of the load characteristic data, which is the same as that shown in FIG. 3A. When the actual X-direction load Fx is Fxr, Lxr is set as the X-direction position Lx based on the load characteristic data indicated by the solid line. Is calculated. In subsequent step S3, a position deviation Mx which is a difference between the optimum tool position lxbest stored in advance in the data storage means 60 and the X-direction position Lx (= Lxr) is calculated. In step S4, only the position deviation Mx is calculated. A command for changing the X-direction position Lx is output to the three-dimensional position control device 66. As a result, the X-direction position Lx of the welding tool 10 is displaced by the position deviation Mx, and is matched with the optimum tool position lxbest, and the friction stir welding is performed with the optimum load fxbest. This optimum load fxbest corresponds to the target load.

  Thus, according to the friction stir welding apparatus 40 of the present embodiment, when the friction stir welding is performed by moving the welding tool 10 along the welding line W, the X direction substantially perpendicular to the welding line W is performed. In order to move the welding tool 10 along the joining line W while adjusting the position Lx in the X direction so that the load Fx becomes a predetermined target load (optimum load fxbest), a pair of joined members 42 and 44 Regardless of the difference in material (hardness, etc.) and the dimensional error of the joined portion represented by the joining line W, excellent joining quality according to the target load can be stably obtained. In particular, the X-direction load Fx can be detected easily and with high accuracy as compared with the case of detecting the actual joining line W, that is, the butting position of the members 42 and 44 to be joined. Friction stir welding obtained stably can be carried out easily.

  Since the X-direction position Lx is adjusted so that the X-direction load Fx becomes the target load (optimum load fxbest) in this way, the X-direction load Fx greatly exceeds the target load (optimum load fxbest). Thus, the wear of the stirring protrusion 14 due to the uneven load is suppressed, and the life of the welding tool 10 is improved.

  In this embodiment, when the friction stir welding is performed by moving the welding tool 10 along the welding line W, the actual load X in the X direction is detected, and the X direction based on the preset load characteristic data is detected. An X-direction position Lx corresponding to the load Fx is calculated, a position deviation Mx between the X-direction position Lx and a predetermined optimum tool position lxbest is obtained, and the X-direction position Lx of the welding tool 10 is calculated by the position deviation Mx. For example, the X-direction position Lx is quickly displaced to the optimum tool position lxbest compared to the feedback control of the X-direction position Lx so that the X-direction load Fx matches the target load (optimum load fxbest). As a result, the joining tool 10 is well held at the optimum tool position lxbest, and the joining quality is further stabilized.

  In the present embodiment, the X-direction position Lx of the welding tool 10 with respect to the welding line W is continuously changed, and the X-direction load Fx acting on the welding tool 10 is continuously detected. Since the data acquisition means 62 for acquiring the load characteristic data representing the relationship between the X-direction position Lx and the X-direction load Fx is provided, friction stir is performed under various joining conditions such as different materials of the joined members 42 and 44. Even in the case of joining, the load characteristic data corresponding to the actual joining conditions can be easily obtained by performing preliminary friction stir welding along the data acquisition line Wd shown in FIG. The optimum tool position lxbest at which the best joint quality can be obtained from the load characteristic data is obtained by examining the joint quality of each part on the joint line W and obtaining the optimum point Q. It can be easily set as required.

  In the above embodiment, the actual X-direction load Fx is detected, the X-direction position Lx corresponding to the X-direction load Fx is calculated based on preset load characteristic data, and the X-direction position Lx The position deviation Mx with respect to the determined optimum tool position lxbest is obtained, and the X-direction position Lx of the welding tool 10 is displaced by the position deviation Mx. The X-direction load is set with the optimum load fxbest as a target load. The X-direction position Lx may be feedback controlled in accordance with the deviation of these loads so that Fx matches the target load (optimum load fxbest). In this case, the load characteristic data and the optimum tool position lxbest are not necessarily required because it is only necessary to know the optimum load fxbest for obtaining the best joining quality.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention implements in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

It is a schematic perspective view explaining the principal part at the time of carrying out friction stir welding of a pair of to-be-joined member which consists of a dissimilar metal material according to the method of this invention. It is a block diagram explaining the function with which the electronic control apparatus of FIG. 1 is provided. FIGS. 3A and 3B are diagrams illustrating load characteristic data stored in the data storage unit of FIG. 2, in which FIG. 3A is a diagram illustrating an example of load characteristic data, and FIG. It is a figure which demonstrates concretely the dimension of each part, joining conditions, etc. at the time of actually acquiring load characteristic data according to the data acquisition method of (b) of FIG. 3 is a flowchart for specifically explaining a function of an X-direction position correcting unit in FIG. 2. It is a figure explaining the procedure at the time of calculating X direction position Lx from X direction load Fx using load characteristic data at Step S2 of FIG. It is a figure explaining friction stir welding, (a) is a schematic perspective view, (b) is an enlarged view of the VIIB-VIIB cross section in (a). The positional relationship between the joining line W and the tool shaft center S when joining a pair of members to be joined in the friction stir welding in FIG. 7 and the material of the members to be joined were changed, and the feasibility of the friction stir welding was examined. It is a figure explaining a result.

Explanation of symbols

  10: Joining tool 14: Stirring protrusion 40: Friction stir welding device 42, 44: Member to be joined 56: Load sensor (load detection means) 60: Data storage means 62: Data acquisition means 64: X direction position correction means ( X direction position adjusting means) S: Tool axis W: Joining line Lx: X direction position Fx: Load in X direction fxbest: Optimal load (target load) lxbest: Optimal tool position Step S1: Load detection step Step S2: Position calculation Step, position calculation means Step S3: Position deviation calculation step, position deviation calculation means

Claims (5)

While rotating a joining tool having a stirring protrusion protruding at the tip about the axis S, the stirring protrusion is pressed onto a joining line W where the edges of the pair of members to be joined are abutted with each other. , By softening the member to be joined by frictional heat and immersing the stirring protrusion, and by relatively moving the joining tool along the joining line W, the vicinity of the edges of the pair of members to be joined In the friction stir welding method in which the stirring protrusions are agitated and mixed together and integrally joined,
The pair of members to be joined are made of different metals having different hardnesses,
When the friction stir welding is performed by relatively moving the welding tool along the welding line W, the welding is performed so that the X-direction load Fx intersecting the welding line W becomes a predetermined target load. A friction stir welding method, wherein the tool is relatively moved along the joining line W while adjusting the position of the tool in the X direction. Load characteristic data representing the relationship between the X-direction position Lx of the welding tool relative to the welding line W and the X-direction load Fx acting on the welding tool, and the X-direction position where an appropriate joining state is obtained A data storage means in which the optimum tool position lxbest set as Lx is stored in advance;
A load detecting step of detecting an actual X-direction load Fx when performing friction stir welding by relatively moving the welding tool along the welding line W;
A position calculating step of calculating an X direction position Lx corresponding to the X direction load Fx based on the load characteristic data;
A position deviation calculating step of calculating a position deviation Mx between the X direction position Lx and the optimum tool position lxbest;
The friction stir welding method according to claim 1, wherein the position Lx in the X direction of the welding tool is displaced by the position deviation Mx. While rotating a joining tool having a stirring protrusion protruding at the tip about the axis S, the stirring protrusion is pressed onto a joining line W where the edges of the pair of members to be joined are abutted with each other. , By softening the member to be joined by frictional heat and immersing the stirring protrusion, and by relatively moving the joining tool along the joining line W, the vicinity of the edges of the pair of members to be joined In the friction stir welding apparatus that stirs and mixes the stirring protrusions and integrally joins,
The pair of members to be joined are made of different metals having different hardnesses,
Load detecting means for detecting an X-direction load Fx intersecting the welding line W when performing friction stir welding by relatively moving the welding tool along the welding line W;
X-direction position adjusting means for adjusting the position of the joining tool in the X direction so that the X-direction load Fx detected by the load detecting means becomes a predetermined target load;
A friction stir welding apparatus comprising: Load characteristic data representing the relationship between the X-direction position Lx of the welding tool relative to the welding line W and the X-direction load Fx acting on the welding tool, and the X-direction position where an appropriate joining state is obtained A data storage means in which the optimum tool position lxbest set as Lx is stored in advance;
The X-direction position adjusting means is
When performing friction stir welding by relatively moving the welding tool along the welding line W, an X-direction position Lx corresponding to an actual X-direction load Fx detected by the load detection means is used as the load characteristic data. Position calculating means for calculating based on
Position deviation calculating means for calculating a position deviation Mx between the X direction position Lx and the optimum tool position lxbest;
The friction stir welding apparatus according to claim 3, wherein the position Lx of the welding tool is displaced by the position deviation Mx. When the friction stir welding is performed in accordance with actual welding conditions while the welding tool is relatively moved along the welding line W, the X-direction position Lx of the welding tool with respect to the welding line W is changed, and the welding tool The data acquisition means which detects the X direction load Fx which acts on a tool, and acquires load characteristic data showing the relation between the X direction position Lx and the X direction load Fx. 4. The friction stir welding apparatus according to 4.

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