JP4413677B2 - Point joining method for dissimilar metal parts - Google Patents

Description

  The present invention relates to a point joining method for dissimilar metal members, and in particular, when a plurality of metal members having different materials and different hardnesses are overlapped and the overlapped portions are spot joined. The present invention relates to a technique that can effectively improve the bonding strength.

  In recent years, from the viewpoint of protecting the global environment and saving energy, it has been required to suppress the generation of harmful gases and carbon dioxide emitted from automobiles, improve fuel efficiency, and the like. And in order to satisfy such a demand, weight reduction of the automobile is the most effective, and in body members and various parts, conversion from steel materials to aluminum alloy materials is actively studied. However, it is difficult in terms of cost to make all the materials of body members and various parts constituting an automobile into an aluminum alloy. For this reason, when using an aluminum alloy material, different types of steel and aluminum alloy are used. Bonding between metals, so-called hybrid bonding, is unavoidable, and this dissimilar metal bonding is an important issue.

  In addition, the dissimilar metal bonding between the aluminum alloy and the steel is not limited to the transportation field represented by the automobile as described above, but also in various fields such as home appliances and building materials. It has been demanded. Furthermore, not only aluminum alloys but also magnesium alloys or copper alloys, and different types of metal joining steel are required to be firmly joined.

However, when an aluminum (alloy) material and an iron material such as steel are joined by a fusion welding method generally used for joining metal materials, each metal melts at the time of joining, and the joining interface between them. In addition, brittle and hard intermetallic compounds (Fe ₂ Al ₅ , FeAl _3, etc.) are produced, which causes a problem that the bonding strength is weakened.

  For this reason, in dissimilar metal bonding, various bonding methods such as caulking, rivet bonding, mechanical bonding such as bolt bonding, exposure, bonding, and rotary friction welding have been studied in order to ensure sufficient bonding strength. However, any of these methods has some inherent problems to be put into practical use.

  For example, in mechanical clinching (Non-Patent Document 1) such as Tox (R) method and Toglock method, which are mechanical joints, male and female jigs are pressed with a lap joint sandwiched between them. The plate material on the side is caulked with the plate material on the female mold side, but when dissimilar metals are joined by such a joining method, there is no problem of intermetallic compounds as described above, but characteristics such as ductility and thermal expansion coefficient are obtained. Since different metals are mechanically joined together, when pressed, the superposed surfaces of dissimilar metals are in close contact and are not pushed into the female mold, making it impossible to join firmly, or the temperature after joining There was a risk of loosening due to environmental load such as rising. Similarly, in the case of rivet joining and bolt joining, which are mechanical joints, there is a risk that loosening may occur due to an environmental load such as a rise in temperature, and a third member such as a rivet or bolt is necessary. Thus, there is a problem that the joining cost increases. Furthermore, there are problems such as the need to secure large-scale equipment and a place where explosion sound does not become a problem. Adhesion tends to cause deterioration and long-term reliability of bonding strength. There is a problem that it is low and takes time for curing. Further, even in the rotary friction welding, there are problems such as a low reliability of the joint and a restriction that the shape of the joint is limited to a pipe or a rod.

  For this reason, the present inventors, together with the other inventors, previously solid-state bonded in Patent Document 1 in a state where the heat input at the time of bonding is small and the material to be bonded is plastic fluidized without melting. A method of joining a soft aluminum alloy material and a hard steel member by friction stir welding was proposed. More specifically, as shown in FIG. 1, a soft aluminum alloy material 2 and a steel material 3 to be joined are placed on a hard backing member 1 so that the aluminum alloy material 2 is on the upper side. A pin-like hard probe 6 protruding from the shoulder surface 5 of the rod-shaped rotating jig 4 rotated at high speed around the axis is superposed on the superposed portion, and the shoulder surface 5 is made of the aluminum alloy material 2. Insert the probe 6 so that the tip of the probe 6 does not contact the hard steel material 3 until it contacts the surface, generate frictional heat, and stir the aluminum alloy material 2 plastically fluidized by the frictional heat with the hard probe 6. And the method of joining the aluminum alloy material 2 and the steel material 3 was proposed. Then, it was clarified that the generation of intermetallic compounds can be advantageously suppressed or prevented, and the aluminum alloy-steel can be securely bonded, and the bonding strength (joint strength) by tensile shear can be improved. However, even with a bonding material (joint) joined by such a friction stir welding method, it is difficult to say that the joining strength, particularly the cross peel strength, is still sufficient, and it is added to the joint. Depending on the deformation, there is a problem in practical use. For this reason, a further improvement in bonding strength is desired.

  Patent Document 2 also proposes a technique for friction stir welding of dissimilar metal materials, in which the tip of the probe of the friction stir jig extends from the low melting point material side to the high melting point side material. However, since the probe is usually made of steel, when this method is applied to the joining of aluminum alloy and steel, the probe is made of steel. There is a problem that the life of the jig is extremely shortened.

Aluminum Technical Handbook Editorial Committee, “Aluminum Technical Handbook”, new edition, Karos Publishing Co., Ltd., November 18, 1996, p803-804 JP 2003-275876 A JP 2003-170280 A

  Here, the present invention has been made in the background of such circumstances, the problem to be solved is to superimpose the plate-like portions of a plurality of metal members of different materials and different hardness, An object of the present invention is to provide a method for joining dissimilar metal members capable of improving the joining strength without considering the life of the jig when spot-joining the superposed portions.

  In the present invention, in order to solve the above-described problem, a method of overlapping the plate-like portions of the first and second metal members having different materials and different hardnesses, and spot-joining the overlapped portions. Then, the plate-like portion of the first metal member is overlapped with the plate-like portion of the second metal member that is harder than the first metal member, and In the part to be point-joined, a concave jig provided with a depression recess into which the material of the metal member is pushed is arranged on the second metal member side, while on the first metal member side, the concave jig is provided. Rotating around the axis with a structure in which a convex part for pushing the material of the first and second metal members into the concave depression of the concave jig is provided concentrically on the tip surface of the rod-shaped jig body By arranging a possible convex jig, the convex mold for the part to be point-joined After inserting the material of the first and second metal members into the depression recess of the concave jig by inserting the convex part of the tool from the surface side of the plate-like part of the first metal member, the difference Under the inserted state, the rotation of the convex jig is started, and at least the first metal member pushed into the pushing recess is plastically flowed by the friction stir action. A point joining method for dissimilar metal members, characterized in that one metal member and the second metal member are intimately joined to each other, is a first aspect thereof.

  Moreover, in a desirable second aspect of the method for point joining of dissimilar metal members according to the present invention, the tip of the convex part of the inserted convex jig is connected to the plate-like part of the first metal member and the second part. The rotation of the convex jig is started at a position entering the second metal member side rather than the overlapping surface with the plate-like portion of the metal member.

  Furthermore, in the third aspect of the point joining method for dissimilar metal members according to the present invention, the convex portions of the convex jig are inserted, and the first and second metal members are inserted into the depressions of the concave jig. By pushing and filling the material, the material of the first metal member spreads radially outward at the front end portion of the convex portion of the convex jig in the insertion direction. A configuration in which the first metal member is mechanically engaged with the second metal member is advantageously employed.

  In addition, in the fourth aspect of the present invention, as the concave jig, the side surface of the indentation recess is a cylindrical surface, and the bottom surface of the indentation recess is an annular groove formed in the outer peripheral portion. Therefore, a stepped surface in which the depth of the outer peripheral portion is deeper than the depth of the central portion is used.

  Further, in the fifth aspect of the present invention, as the concave jig, a stepped cylindrical surface in which a side surface of the indentation recess bulges radially outward at a portion reaching a predetermined height from the bottom surface; What is being used is used.

  Then, according to the first aspect described above in the point joining method of dissimilar metal members according to the present invention, first, the plate-like portions of a plurality of metal members having different materials and different hardnesses are overlapped and then point joined. The part to be overlapped in the overlapping direction is sandwiched between a pair of convex jigs and concave jigs and pressed, so that the concave parts corresponding to the concave parts of the concave jigs are formed on the plate-like parts of the two metal members. Form. At that time, a convex jig having a convex portion arranged concentrically on the tip surface of the rod-shaped jig main body and rotatable about the axis is used, while a concave concave jig is used as the concave jig. Use the one provided with a place. The pair of the convex jig is positioned on the soft metal member (first metal member) side, and the pair of the concave jig is positioned on the hard metal member (second metal member) side. Are placed opposite each other with two metal members interposed therebetween, and the convex portion of the non-rotating convex jig is moved from the surface side of the plate-like portion of the soft metal member to the concave jig. By inserting into the indentation recess, the material of the two metal members is indented into the indentation recess of the concave jig to form the recess. After that, with the convex portion of the convex jig inserted into the concave portion, the convex jig starts to rotate so that at least the jig main body and the convex portion of the convex jig are in contact with each other. The soft metal member (first metal member) is plastically fluidized with frictional heat and stirred, so that the soft metal member (first metal member) and the hard metal member (second metal) are stirred. Member) will be brought into close contact with each other.

  As described above, in the first embodiment, prior to the friction stir welding, the soft metal member (the first metal member) is pushed into the pressing recesses of the concave jig by being pushed into the two metal members having different materials and different hardnesses. Since the friction stir welding is performed after forming the concave portion where the surface side of the plate-like portion of the metal member of the metal member) is recessed, the joint area is smaller than that of the simple point welding by the conventional friction stir welding method. Is advantageously increased, so that the bonding strength can be effectively improved.

  In addition, since at least the material of the soft metal member is plastically flowed by the friction stir action, the surface of the hard metal member (second metal member) on the superposed surface (joined part) of the concave portion is used. The plastic fluidized soft metal member (first metal member) is spread so that the material does not fit into it, so that a minute gap is not formed. Is realized.

  Further, according to the second aspect of the method for point joining of dissimilar metal members according to the present invention, the tip of the convex portion of the convex jig is around the portion where the convex portions of the plate-like portions of the two metal members are inserted. From the time when the hard metal member (second metal member) side enters the side of the superposed surface, a) the tip surface of the jig body of the convex jig is a soft metal member (first metal member). Until the point of contact with the surface, or b) the position until the tip of the jig body of the convex jig slightly enters the concave jig side from the surface of the soft metal member (first metal member). If the rotation of the convex jig is started, the above-described effect can be obtained more advantageously. In particular, when the tip of the convex part of the convex jig enters the hard metal member (second metal member) side from the superposed surface, the rotation of the convex jig is started. Thus, the plastic flow is induced more quickly, and the point joining can be performed in a short time.

  Furthermore, according to the third to fifth aspects of the point joining method of dissimilar metal members according to the present invention, after the two metal members are brought into a mechanical engagement state, that is, after being mechanically joined, Since the friction stir welding is now performed, the effects of mechanical joining and friction stir welding are combined to improve the joint strength extremely effectively, which greatly improves the reliability of the joint. improves.

  Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

  First, FIG. 2 shows a pair of convex jigs 10 facing each other in a state in which two metal plates 14 and 16 of different materials and different hardness, which are point-bonded according to the present invention, are overlapped in the vertical direction. And the concave jig 12.

  More specifically, of these two metal plates, the upper plate 14 disposed on the side of the convex jig 10 positioned above is a first metal member, for example, aluminum or Among various metal materials such as aluminum alloy, magnesium, magnesium alloy, copper, copper alloy, etc., it is a metal plate made of a relatively soft material, and is disposed so as to be in contact with the upper surface of the concave jig 12 positioned below. The lower plate 16 is a second metal member, for example, a metal plate made of a hard material such as steel or iron. The soft metal plate 14 and the hard metal plate 16 are fixed and restrained by a fixing jig (not shown) so as not to move relatively in the vertical direction and the horizontal direction.

  The convex jig 10 has a jig main body 18 that is rotated at a high speed around an axis by a driving device (not shown) and that can move in a direction (vertical direction) close to and away from the concave jig 12. Configured. The jig main body 18 has a rod shape as a whole, and a cylindrical convex portion 22 that protrudes downward at a predetermined length is concentric at the center of the circular tip surface (shoulder surface) 20 thereof. Provided. And this convex part 22 and the front end surface 20 in which it is provided are formed with the material harder than the soft metal plate 14 at least, and those wear are prevented.

  On the other hand, the concave jig 12 facing the convex jig 10 in the state where the two metal plates 14 and 16 are interposed is made of a hard material, and as is apparent from FIGS. As a whole, it has a cylindrical shape, and a pressing recess 24 having a predetermined depth is formed on the upper surface 23 thereof. More specifically, the indentation recess 24 has a cylindrical surface with a side surface 26 of a cylindrical shape, and a bottom surface 28 of the indentation recess 24 by an annular groove 30 formed in an outer peripheral portion having an arc shape in cross section. The depth of the outer peripheral portion where the groove portion 30 is formed is a stepped surface that is deeper than the depth of the central portion. Further, the depth of the central portion of the depression recess 24 is made larger than the protruding length of the projection 22 of the convex jig 10 described above, and the diameter of the opening of the depression recess 24 is as follows. The diameter of the convex portion 22 of the convex jig 10 is larger than that of the convex portion 10 and smaller than the diameter of the tip surface 22 of the convex jig 10.

  Thus, when performing point joining of the soft metal plate 14 and the hard metal plate 16 having different materials and different hardnesses using the pair of convex jigs 10 and the concave jig 12 as described above, for example, The operation will proceed according to the following procedure.

  That is, first, as described above, the two metal plates 14 and 16 are arranged so that the soft metal plate 14 is disposed on the convex jig 10 side and the hard metal plate 16 is disposed on the concave jig 12 side. While the metal plates 14 and 16 are overlapped in the vertical direction, the metal plates 14 and 16 are recessed so that the portion to be point-joined of the overlapped metal plates 14 and 16 covers the pushing recess 24 of the recessed jig 12. It is arranged on the upper surface 23 of the tool 12, and is fixed and restrained so that they do not move relatively in the horizontal direction or the vertical direction. As described above, since the soft metal plate 14 is disposed on the convex jig 10 side (upper side), a decrease in the life of the convex jig 10 can be advantageously prevented. However, when the hard metal plate 16 is disposed on the convex jig 10 side (upper side), the tip surface 20 and the convex portion 22 of the convex jig 10 have the same material and hardness at the time of friction stir welding described later. This is because the hard metal plate 16 made of the above material is worn out or damaged, resulting in a problem that the life of the convex jig 10 is shortened.

  Thereafter, the convex jig 10 is moved downward toward the opposed concave jig 12, and the convex portion 22 of the convex jig 10 is inserted and pressed from the upper surface side of the soft metal plate 14. is there. Then, by inserting the convex portion 22 of the convex jig 10, the material of the portion to be point-joined of the metal plates 14 and 16 is pressed, and as shown in FIG. The material of the portion to be spot-bonded of the metal plates 14 and 16 is pushed into the place 24. At this time, the convex jig 10 does not rotate around the axis and presses the part to be point-joined between the two metal plates 14 and 16 without rotation. Therefore, in such a portion, the convex portion 22 of the convex jig 10 does not penetrate the soft metal plate 14 in the thickness direction, that is, the tip of the convex portion 22 of the convex jig 10 is hard. There is no contact with the metal plate 16, and the material of the metal plates 14 and 16 is pushed into the pushing recess 24 of the concave jig 12 while being stretched and thinned by so-called drawing.

  Then, the overlapping portion of the metal plates 14 and 16 is pushed in, and the lower surface of the overlapping portion reaches the bottom surface 28 of the pushing recess 24 of the recessed jig 12 (FIG. 4). The convex portion 22 of the jig 10 is moved toward the bottom surface 28 of the indentation recess 24 until the front end surface 20 of the jig main body 18 of the convex jig 10 abuts against the upper surface of the soft metal plate 14 or soft. When inserted to a position where it slightly enters below the upper surface of the metal plate 14, the materials of the metal plates 14 and 16 are buckled at the bottom 28 side of the depression 24 as shown in FIG. 5. The material of the metal plates 14 and 16 is pushed into the groove 30 formed in the outer peripheral portion of the bottom surface 28 of the pushing recess 24 to fill the pushing recess 24.

  Thereby, the soft metal plate 14 located on the upper side extends radially outward at the tip portion (A portion in FIG. 5) on the front side in the insertion direction of the convex portion 22 of the convex jig 10, and projects. In this part, the soft metal plate 14 is mechanically engaged (mechanically joined) so as to bite into the hard metal plate 16. Further, a concave portion 32 having an inner surface having a shape corresponding to the outer surface of the convex portion 22 of the convex jig 10 is formed in the overlapped portion of the metal plates 14 and 16.

  In the present embodiment, as described above, after the convex portion 22 of the convex jig 10 is inserted and mechanically joined, the state is still inserted into the concave portion 32 of the metal plates 14 and 16. Then, by operating a driving device (not shown) and rotating the convex jig 10 around the axis at a high speed, the jig main body 18 and the convex portion 22 are integrally rotated.

  Thereby, as shown in FIG. 6, between the soft metal plate 14 pressed by the front end surface 20 of the jig body 18 rotated at high speed, and the convex portion 22 and the soft metal plate 14 rotated at high speed. In the meantime, frictional heat is generated and the surroundings are heated by the frictional heat, so that at least the material of the soft metal plate 14 of the recessed portion 32 is made in a state in which plastic flow is possible, while the convex portion 22 is formed. By agitating the plastic fluidized material at a high speed rotation, the soft metal plate 14 is brought into close contact with the hard metal plate 16, and the plate materials are joined. At this time, the material of the hard metal plate 16 of the recessed portion 32 is also heated from the interface by the heat conducted from the soft metal plate 14 side, but generally does not reach plastic fluidization. There are many cases.

  Then, after such point joining, as shown in FIG. 7, the convex jig 10 is moved upward while being rotated, and from the concave portion 32 of the overlapping portion of the metal plates 14 and 16. Then, the convex portion 22 of the convex jig 10 is pulled out, and the concave jig 12 is moved downward, so that the concave portion formed in the overlapped portion of the metal plates 14 and 16 from the pushing recess 24 of the concave jig 12. By removing the part 32, one point joining operation is completed. In the present embodiment, since the convex portion 22 of the convex jig 10 is pulled out in a rotated state, the inner surface of the concave portion 32 is a smooth surface compared to the case where it is pulled out in a non-rotating state. It is said. However, the convex portion 22 of the convex jig 10 can be pulled out in a non-rotating state, and the concave portion 32 can of course be filled by a known method.

  Thus, in this embodiment, the recessed part 32 was formed in the overlap part of the two metal plates 14 and 16 from which a material and hardness differ using a pair of convex jig | tool 10 and the concave jig | tool 12. After that, with the convex portion 22 of the convex jig 10 being inserted into the concave portion 32, the convex jig 10 is started to rotate and friction stir welding is performed. Compared with the simple spot welding by the conventional friction stir welding method as shown in FIG. 1, the joining area is advantageously increased. That is, in the present embodiment, the metal plates 14, 16 are not only at the front end side portion of the convex portion 22 of the convex jig 10 but also at the side surface side portion of the convex portion 22 at the interface between the metal plates 14, 16. Since 16 is closely joined, the joining strength can be effectively increased as compared with the point joining by the conventional friction stir welding.

  In addition, since at least the material of the soft metal plate 14 is plastically flowed by the friction stir action of the convex jig 10 in the concave portion 32, the soft metal plate stirred by the convex portion 22 of the convex jig 10 is used. 14 material spreads so that it may become familiar with the surface (interface) of the hard metal plate 16, and they are in close contact with each other, and the material of the heated soft metal plate 14 and the material of the hard metal plate 16 are bonded to each other. Bonding can be realized. Further, since the bonding is performed without melting the soft metal plate 14 having a relatively low melting point, a fragile metal is formed on the overlapping surface (interface) between the soft metal plate 14 and the hard metal plate 16. The formation of intermetallic compounds can also be suppressed or prevented very effectively, and the joining quality can be secured stably.

  Moreover, in the present embodiment, as described above, the two metal plates 14 and 16 are joined by friction stir welding, and the soft metal plate 14 and the hard metal plate 16 are connected to the recessed portion 32. Since the portion on the bottom side (part A in FIG. 5) is mechanically engaged, the joining strength by friction stir welding is further reinforced by mechanical joining. Combined with the effect of bonding, the bonding strength can be greatly improved as compared with the conventional case. As a result, the reliability of the joint is greatly improved.

  Moreover, in this embodiment, after inserting the convex part 22 of the convex jig | tool 10 of a non-rotation state and forming the recessed part 32 in the overlapping part of the metal plates 14 and 16, the convex part 22 inserted is Since the rotation of the convex jig 10 is started as it is in the inserted state without being pulled out, the formation of the recessed portion 32 and the friction stir welding are performed by a series of continuous operations. Thus, it is possible to perform point joining quickly and effectively with good workability. Further, after the convex jig 10 and the concave jig 12 are used as punches and dies in press working (drawing), respectively, they are further used as a friction stir tool and a backing jig in ordinary friction stir welding. Since it is used like a tool, an increase in the number of jigs and tools can be advantageously prevented. For this reason, an increase in bonding cost can be advantageously suppressed or avoided.

  Therefore, according to such a point joining method of dissimilar metal members according to the present invention, it is possible to increase the joining strength of the joining material with good workability, thereby making it possible to use materials such as transportation equipment, building materials, and home appliances. In addition, in a production line that joints workpieces having different hardnesses, joining of dissimilar metal members is advantageously performed.

  The exemplary embodiments of the present invention have been described in detail above. However, the embodiments are merely examples, and the present invention is limited in any way by specific descriptions according to such embodiments. It should be understood that it is not interpreted.

  For example, in the above embodiment, the metal plates 14 and 16 that are plate materials are used as the members to be joined (joined materials), but the shape of the joined materials is not limited to the plate materials. Instead, as long as the superposed portions to which point bonding is performed are plate-shaped or face-plate-shaped, respectively, any can be adopted.

  Further, in the above example, until the tip surface 20 of the jig body 18 of the convex jig 10 abuts on the upper surface of the soft metal plate 14 or until it enters slightly below the upper surface of the soft metal plate 14, In other words, after the bottom dead center or the lowest point (X in FIG. 5) is inserted and the material of the metal plates 14 and 16 is filled into the pressing recess 24 of the concave jig 12, the convex mold is repaired. The tool 10 starts rotating, but the tip of the convex portion 22 of the convex jig 10 is harder than the overlapping surface (Y in FIGS. 4 and 5) of the metal plates 14 and 16. If the rotation of the convex jig 10 is started at a position from the position entering the 16 side to the bottom dead center (X), the bonding strength can be advantageously improved as described above. In particular, while the overlapping portions of the metal plates 14 and 16 are being pushed into the pressing recess 24 of the concave jig 12, the tip of the convex portion 22 of the convex jig 10 is more than the overlapping surface (Y). When the rotation of the convex jig 10 is started when entering the hard metal plate 16 side (downward side), the metal material is compared with the case where it starts when reaching the bottom dead center (X). Thus, the plastic fluidization occurs more quickly, the deformation resistance is lowered, and the point joining can be performed in a shorter time.

  When the rotation of the convex jig 10 is started at a position above the overlapping surface (Y), the metal material is not sufficiently filled into the depression 24 of the concave jig 12. There is a possibility that the soft metal plate 14 and the hard metal plate 16 cannot be mechanically engaged, and the convex portion 22 of the convex jig 10 penetrates in the thickness direction from the upper surface of the soft metal plate 14. Therefore, it is difficult to contact the hard metal plate 16 or to sufficiently increase the bonding area.

  Furthermore, in the above example, as shown in FIGS. 2 to 7, as the concave jig 12, the bottom surface 28 of the push-in recess 24 is a stepped surface whose depth at the center is shallower than the depth of the outer periphery. The (R) type die (die) was adopted, whereby the metal plates 14 and 16 were mechanically joined. In addition to the concave jig 12 having such a structure, For example, a known die (die) used for mechanical joining, such as a toggle lock die (die) shown as the concave jig 34 in FIGS. 8 (a), 8 (b), and 9 is used. Can also be advantageously employed. Specifically, the concave jig 34 is formed by assembling three divided molds 34a, 34b, and 34c made of a hard material that are divided outward in the radial direction, and has a cylindrical shape as a whole. ing. Further, a pressing recess 36 having a predetermined depth is provided on the upper surface. The pushing recess 36 includes a stepped cylindrical surface that bulges out in a circular arc shape in a radially outward direction at a side surface 38 extending from the bottom surface 40 to a half height. Has been. Further, the depth of the pushing recess 36 is made larger than the protruding length of the projection of the convex jig described above, and the diameter of the opening of the pushing recess 36 is set as the convex jig. It is supposed to be larger than the diameter of the convex part. Then, as shown in FIG. 9, when the buckled metal plates 44 and 46 are pushed into the bulging portion 42 of the side surface 38, the soft metal plate 44 located on the convex jig side becomes convex. At the front end portion of the convex portion of the jig in the insertion direction, it expands outward in the radial direction, and the soft metal plate 44 is mechanically engaged with the hard metal plate 46 at this portion. It is.

  Thus, in the above example, the recessed portion 32 is formed by the pushing operation of the metal material into the pushing recess 24 of the recessed jig 12 performed prior to the friction stir welding, while the soft metal plate 14 and the hard metal plate 16 are mechanically engaged with each other. However, in the present invention, the formation of the recessed portion 32 increases the bonding area and improves the bonding strength. Therefore, as described above, the soft metal plate 14 and the hard metal plate 16 do not necessarily need to be mechanically engaged. Therefore, the shape of the depression 24 of the concave jig 12 may be a cylindrical shape or a truncated cone shape.

  In the above example, the metal plates 14 and 16 are overlapped in the vertical direction, and the convex jig 10 is moved downward in the vertical direction with respect to the upper surface of such a superposed portion. It is also possible to move the convex jig 10 upward toward the lower surface of the overlapped portion. Further, the metal jigs 14 and 16 are overlapped in the horizontal direction, and the convex jig is horizontally aligned. It is also possible to move 10. However, in these cases, the concave jig 12 that is paired with the convex jig 10 is disposed so as to face the convex jig 10 with the metal plates 14 and 16 interposed therebetween, and the soft metal plate. 14 is arranged on the convex jig 10 side, and the hard metal plate 16 is arranged on the concave jig 12 side.

  Furthermore, in the said embodiment, although the convex part 22 of the convex jig | tool 10 was made into the column shape, the metal material located in the convex part 22 side was able to be stirred efficiently by this. In the present invention, the shape of the convex portion 22 of the convex jig 10 is not limited to the shape of the above example, but a conical shape or a truncated cone shape in which the diameter of the convex portion tapers toward the tip, Any of various known shapes can be employed. Moreover, even if it exists in the shape of the front end surface 20 of the convex jig | tool 10, it is not specifically limited, A flat surface or the concave shape which curves toward the center may be sufficient, and it is well-known conventionally. These shapes can be adopted as appropriate.

  In addition, although not listed one by one, the present invention can be implemented in a mode with various changes, modifications, improvements, and the like based on the knowledge of those skilled in the art. It goes without saying that all are included in the scope of the present invention without departing from the spirit of the invention.

  Hereinafter, representative examples of the present invention will be shown to clarify the present invention more specifically, but the present invention is not limited by the description of such examples. It goes without saying.

  First, a steel convex jig (i) and a concave jig having a structure as shown in FIG. 2 were prepared. Note that the diameter of the tip surface of the convex jig (i) is 12 mm, the diameter of the convex part of the convex jig: 5 mm, the protruding length of the convex jig: 2.5 mm, and the depression of the concave jig. The diameter was 6.5 mm, and the depth of the center of the indentation was 1.3 mm. For comparison, a convex jig (ii) different from the convex jig (i) and a steel plate-like backing jig were prepared for conventional friction stir welding. The convex jig (ii) had a shoulder diameter of 13 mm, a probe diameter of 4.5 mm, and a probe protrusion length of 0.8 mm.

  On the other hand, as a soft metal member, a 6000 series aluminum alloy (6000 series Al) plate material having a thickness of 1 mm and a 5000 series aluminum alloy (5000 series Al) plate material having a thickness of 1 mm are prepared. Prepared a cold rolled steel sheet (SPCC) having a thickness of 0.7 mm and an alloyed hot-dip galvanized steel sheet (SCGA) having a thickness of 0.7 mm.

  As shown in Table 1 below, in Example 1 and Comparative Examples 1 and 2, a 6000 series Al plate material and an SPCC material are combined, and in Example 2, a 5000 series Al plate material and an SPCC material are combined. Furthermore, in Example 3 and Comparative Example 3, a 6000 series Al plate material and an SCGA material were combined, and the two plate materials were superposed and arranged as shown in FIG. However, in Comparative Example 2, instead of the convex jig (i) and the concave jig, the convex jig (ii) and the backing jig having the dimensions described above were arranged.

  And by inserting the non-rotating convex jig into the materials to be joined in Examples 1 to 3 and Comparative Examples 1 and 3, the metal material was pushed into the depression recess of the concave jig and filled. . Thereby, the to-be-joined material of Examples 1-3 and Comparative Examples 1 and 3 was mechanically joined in the site | part of the lower end side of the recessed part.

  Then, friction stir welding was performed on the workpieces of Examples 1 to 3 by rotating the convex jig at a high speed. The friction stir welding conditions were a rotational speed of 1500 rpm and a welding time of 2 seconds.

  On the other hand, spot welding by the conventional friction stir welding method was performed on the materials to be joined of Comparative Example 2 under the conditions of a rotation speed of 1500 rpm and a joining time of 2 seconds.

Then, as described above, using the bonding material subjected to point bonding, a tensile shear test and a cross peel test were performed, and the bonding strength obtained in each test was determined as “◯”, “Δ”, Evaluation was made in three stages of “x”, and the results are shown in Table 1 below. The evaluation criteria are as follows.
[Tensile shear load] ○: 2.5 kN or more, Δ: 1.5 to 2.5 kN, ×: Less than 1.5 kN [Cross peeling load] ○: 1.5 kN or more, Δ: 1.0 to 1.5 kN, X: Less than 1.0 kN

  As is apparent from the results of Table 1, when Example 1 in which the same combination of metal plates are joined is compared with Comparative Examples 1 and 2, Example 1 has both a tensile shear strength and a cross peel strength. In contrast, in Comparative Example 1, the tensile shear strength is Δ, and in Comparative Example 2, the tensile shear strength is Δ and the cross peel strength is x. Similarly, when Example 3 and Comparative Example 3 are compared, the tensile shear strength is x in Comparative Example 3, but is Δ in Example 3. Therefore, it can be seen that if different kinds of metal members are spot-bonded according to the present invention, joint strength such as tensile shear strength and cross peel strength can be improved advantageously.

It is explanatory drawing which shows an example of the process of carrying out the point joining of the two metal members from which a material and hardness differ according to the conventional friction stir welding method. It is explanatory drawing which shows an example of the process of spot-joining two metal members from which a material and hardness differ according to this invention, Comprising: Two metal members piled up between a pair of convex jig | tool and a concave jig | tool Indicates a state in which is arranged. FIG. 3 is an explanatory plan view of the concave jig shown in FIG. 2. It is explanatory drawing which shows an example of another process of point-joining two metal members from which a material and hardness differ according to this invention, Comprising: The convex part of a convex jig | tool is inserted with respect to the two metal members piled up. It shows the status. It is explanatory drawing which shows an example of another process of carrying out the point joining of the two metal members from which a material and hardness differ according to this invention, Comprising: The material of the two metal members piled up in the pressing recess of a concave jig | tool is The filled state is shown. It is explanatory drawing which shows an example of another process of spot-joining two metal members from which a material and hardness differ according to this invention, Comprising: The state which rotated the convex jig | tool at high speed is shown. It is explanatory drawing which shows an example of another process of carrying out the point joining of the two metal members from which a material and hardness differ according to this invention, Comprising: A convex jig | tool and a concave jig | tool are joined from two joined metal members. The separated state is shown. It is explanatory drawing which shows another example of the concave jig | tool employ | adopted in this invention, Comprising: (a) is a plane explanatory drawing, (b) is bb cross-sectional explanatory drawing of (a). It is explanatory drawing which shows an example of the process of carrying out the point joining of the two metal members from which a material and hardness differ using the concave jig | tool shown by FIG. 8, Comprising: Two piled up in the pressing recess of a concave jig | tool A state in which the material of the metal member is filled is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Convex jig | tool 12, 34 Concave jig | tool 14,44 Soft metal plate 16,46 Hard metal plate 18 Jig body 20 Front end surface 22 Convex part 24,36 Pushing recess 26,38 Side face 28,40 Bottom face 30 Groove part 32 Recessed part 42 Swelling part

Claims (5)

A method in which the plate-like portions of the first and second metal members having different materials and different hardnesses are overlapped, and the superposed portion is spot-joined,
The plate-like portion of the first metal member is overlapped with the plate-like portion of the second metal member, which is harder than the first metal member, and the joined plate-like portions are spot-joined. In a portion to be provided, a concave jig provided with a pressing recess into which the material of the metal member is pushed is disposed on the second metal member side, while the concave jig is disposed on the first metal member side. Convex part that is concentrically provided on the front end surface of the rod-shaped jig body, and that can be rotated around the axis. The concave jig is arranged by inserting the convex part of the convex jig from the surface side of the plate-like part of the first metal member into the part to be spot-bonded by arranging the mold jig. After pushing the material of the first and second metal members into the indentation recess of Then, by starting the rotation of the convex jig and performing plastic flow by friction stir action of at least the material of the first metal member pushed into the pushing recess, the first metal A point joining method for dissimilar metal members, characterized in that a member and the second metal member are brought into close contact with each other for point joining.   The tip of the convex portion of the convex jig inserted is more than the overlapping surface of the plate-like portion of the first metal member and the plate-like portion of the second metal member. The point joining method of dissimilar metal members according to claim 1, wherein rotation of the convex jig is started at a position entering the side.   By inserting the convex part of the convex jig and pressing the material of the first and second metal members into the indentation recess of the concave jig, the material of the first metal member is The front end portion of the convex portion of the convex jig expands outward in the radial direction, and the first metal member is mechanically mechanical with respect to the second metal member. The point joining method of the dissimilar metal member of Claim 1 or Claim 2 made into an engagement state.   As the concave jig, the side surface of the indentation recess is a cylindrical surface, and the bottom surface of the indentation recess is formed by an annular groove formed in the outer periphery, so that the depth of the outer periphery is the depth of the center. The point joining method of dissimilar metal members according to claim 3, wherein a stepped surface deeper than that is used. The said recessed jig | tool is what uses the side surface of the said depression recess as the stepped cylindrical surface which bulges radially outward in the site | part which reaches a predetermined height from a bottom face. Point joining method of different metal members.

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