JP4957093B2 - Dissimilar metal joining method - Google Patents

Description

  The present invention provides an electron beam or laser beam with a joint in which a metal material having a melting point lower than these, such as an aluminum alloy, is sandwiched between plates made of a high melting point metal material such as a steel material. It is related with the method of joining using high energy beams, such as these.

  Conventionally, in the joining of dissimilar materials using a high energy beam such as an electron beam or a laser beam, the defocused high energy beam is applied to the high melting point material side in order to suppress the formation of brittle intermetallic compounds. A method has been used in which the low melting point material side of the bonding interface is melted and bonded by irradiation and heat transfer from the high melting point material side.

  In such a case, the welding conditions are controlled, only the material on one side (low melting point material) is melted at the joining interface, and the growth of the intermetallic compound layer is suppressed by joining using the diffusion of the material. By reducing the thickness, it is considered that the strength per unit area of the joint can be increased as compared to the case where both materials are melted and joined together. In addition, a method is described in which a steel plate is stacked on an aluminum alloy and a laser beam is irradiated from above the steel plate to join different materials with the interface in a solid phase / liquid phase state.

Non-Patent Document 2 describes a method of joining an aluminum alloy panel to a steel body frame structure by mechanical fastening, that is, driving a rivet or the like from the aluminum alloy side.
“Overview of the National Conference of the Japan Welding Society”, Japan Welding Society, April 2003, Vol. 72, p. 152 Mitsubishi Motors Technical Review 2004, No. 16, p. 82

However, in the method described in Non-Patent Document 1, the aluminum alloy at the bonding interface is melted by heat transfer from the steel plate. Therefore, the steel plate is always stacked on the aluminum alloy, and the laser beam is emitted from the outer side on the steel plate side. There was a restriction on the structural design of the joints that had to be irradiated.
That is, for the purpose of improving fuel efficiency and athletic performance by reducing the weight of the vehicle, a vehicle body structure using a light alloy such as an aluminum alloy for the vehicle body panel is required. For example, in order to enhance the performance improvement effect by lowering the center of gravity When an aluminum alloy is used for the roof panel, the joining structure between the steel member and the aluminum alloy member, which is a vehicle body skeleton structure, is formed by stacking the roof panel made of aluminum alloy on the steel member, and the proximity of the laser head. This is a joint structure in which a laser beam must be irradiated from the outside of the body frame structure, that is, from the side of the roof panel made of aluminum alloy. Moreover, not only the roof panel, but also when using an aluminum alloy for other vehicle body outer panel, because it becomes a structure in which the aluminum alloy vehicle body panel is overlaid on the steel vehicle body skeleton structure, as described above, A method of irradiating a laser beam from the steel plate side cannot be applied.

  Therefore, in practice, the use of the mechanical fastening method described in Non-Patent Document 2 is conceivable. However, this method has a problem in that there may be restrictions on the appearance and the degree of freedom of design. It was.

  The present invention has been made in view of the above problems in the joining technique of dissimilar metal materials. For example, when applied to the joining of a vehicle body structure using a light alloy roof panel, the invention can be applied from the outside of the vehicle body. It is an object of the present invention to provide a dissimilar metal joining method capable of joining these dissimilar metal materials to each other without impairing the appearance and the degree of freedom of design.

  In order to achieve the above-mentioned object, the present inventors have made extensive studies, and as a result, a steel plate material is further stacked and joined on a light alloy roof panel stacked on a steel body member. Thus, the inventors have found that the above problems can be solved, and have completed the present invention.

That is, the present invention is based on the above knowledge, and in the dissimilar metal joining method of the present invention, the first plate material made of a high melting point material and the second plate material made of a low melting point material are overlapped, When the plate members are lap-joined by irradiation with a high energy beam from the plate member side, a through hole is provided in the second plate member in a stitch shape, and a third high melting point material of the same type as the first plate member is provided on the second plate member. A plate material is further stacked, and the through hole is formed by a high energy beam applied to the third plate material in a state where a protrusion formed on at least one of the first and third plate materials is fitted to the through hole of the second plate material. In this case, the first plate member and the third plate member are intermittently melt-bonded to each other, and then the vicinity of the melt-bonding is pressurized.

  According to the present invention, when a first plate made of a high melting point material and a second plate made of a low melting point material are overlapped, and these plate members are lap-joined by high energy beam irradiation from the second plate side, Since the third plate made of the same high melting point material as that of the first plate is further overlapped and joined to the second plate, for example, the vehicle body having the skeleton structure as described above with a low center of gravity. Assembling of different materials is also possible by irradiating with high energy beam from the outside of the car body, so the restrictions on the joint structure are eliminated and structural design with a high degree of freedom is possible. The degree of freedom can be improved.

  In the following, the method for joining dissimilar metals of the present invention will be described in more detail and specifically.

  In the dissimilar metal joining method of the present invention, as described above, the high energy is obtained with the second plate made of the low melting point material sandwiched between the first plate made of the high melting point material and the third plate. Because the beam is irradiated, a high energy beam is irradiated on the surface of the high melting point material from either side, and in the assembly of an automobile body, the low center of gravity is also obtained by beam irradiation from the outside of the vehicle body. It becomes possible to cope with dissimilar material joining in a skeleton structure vehicle body, and the restrictions on structural design and welding construction are eliminated.

  That is, by passing a second plate material made of a material having a lower melting point than that by a high energy beam irradiated on the surface of the third plate material, the first and third plate materials are melt-bonded. A single plate can be joined at a time. At this time, joining is performed under welding conditions such that the second plate material is penetrated and the first plate material is melted.

When the first plate and the third plate are melt-bonded by penetrating the second plate, the second plate is provided with a through hole in the second plate in advance, and the through hole is provided. Further, a third plate made of a high melting point material of the same type as the first plate is overlaid, and the first plate and the third plate are made to pass through the through-hole by a high energy beam irradiated on the surface of the third plate. By melt-bonding and pressurizing the vicinity of the melt-joint, both sides of the second material are joined to the first and third materials in the vicinity of the melt-joint by this pressurization and heat transfer from the melt-joint, respectively. In the same way as above, restrictions on the joint structure are eliminated, and a structural design with a high degree of freedom becomes possible. In addition to fusion bonding of high melting point materials, a high melting point material is provided around the fusion joint. And low melting point material Therefore, so that the high joint strength can be obtained.

  In the present invention, the first plate material and the third plate material are made of the same kind of high melting point material. In the present invention, “same type” means the same metal structure and component system, and the same. In the present invention, as long as it has a ferrite structure even if it is a different standard such as carbon steel and alloy steel, mild steel and high-tensile steel, etc., it will be “same type” in the present invention.

  FIG. 1 and FIG. 2 are explanatory views of the procedure for joining dissimilar metals in the present invention. FIG. 1 is a side view seen from the direction of movement of the high energy beam B, that is, the direction perpendicular to the joining line. ) To (c) are cross-sectional views taken along cutting lines a, b, and c in FIG.

As shown in these drawings, a second plate material 2 made of a low melting point material (for example, an aluminum alloy material) is overlaid on a first plate material 1 made of a high melting point material (for example, a steel material).
At this time, in the second plate member 2, a long hole 2a (through hole) whose longitudinal direction is the joining progress direction is intermittently formed in advance in a stitch shape, and on the second plate member 2, A third plate 3 made of a high melting point material (for example, steel) is stacked.

A laser beam B focused on the surface of the second plate 2 from the side of the third plate 3 is irradiated as a high energy beam at a position directly above the long hole 2a while moving along the long hole 2a. As shown in FIG. 2 (b), the third plate 3 is melted down and melted together with the first plate 1, and the plate 3 and the plate 1 are melted and joined, and immediately after the laser irradiation position is added. The third roller 3 is pressed by the pressure roller 10 in the direction in which it is pressed against the first plate 1.
The second plate material 2 is heated by heat transfer from the joint portion of the plate material 3 and the plate material 1 which are melt-bonded by the irradiation of the laser beam B, and the heating and pressurization by the pressure roller 10 cause the heating to occur in FIG. As shown, the interface between the first plate member 1 and the second plate member 2 and the interface between the third plate member 3 and the second plate member 2 are joined at the joints 4 and 5.

At this time, as shown to Fig.3 (a)-(c), the shape of the long hole 2a formed in the 2nd member 2 in one or both of the said 1st board | plate material 1 and the 3rd board | plate material 3 Protrusions 1a and 3a matching the size and interval of the first plate member 1 and the third plate member 1 are provided in advance. Since it becomes easier to contact the board | plate material 3, it becomes possible to melt-bond these board | plate materials 1 and 3 efficiently.
In addition, although the said figure shows the example which formed protrusion 1a, 3a in both board | plate materials 1 and 3, and made these protrusion front-end | tips contact previously, protrusion 1a or 3a is shown only in one side of board | plate materials 1 and 3. May be provided. Further, it is not always necessary to bring the tip of the protrusion into contact with the mating plate material, and the plate materials 1 and 3 come closer to each other by forming the protrusion, so that a certain effect can be obtained.

  At this time, between the first plate 1 and the second plate 2 and between the third plate 3 and the second plate 2, these materials are different from each other, and the first plate It is desirable to interpose at least one of the third plate members 1 and 3 and the second plate member 2 with a fourth material that causes eutectic melting. By doing so, the first plate member 1 and the second plate member 2 are disposed. Since eutectic melting occurs at a relatively low temperature at the dissimilar material interface in the vicinity of the melt-bonded portion due to heat transfer and pressurization from the melt-bonded portion to the oxide joint, the oxide film is removed from the bond interface at a lower temperature. It is possible to prevent the rise of the bonding interface temperature, suppress the formation of intermetallic compounds, and the new surfaces of the plate materials made of different metals will be firmly bonded together, especially like aluminum materials and magnesium materials A dense oxide film is formed on the surface It can be suitably used for bonding dissimilar metals including fees.

  At this time, as a specific means for interposing the fourth material between the plate materials, it is desirable to plate the fourth material on at least one joint surface of the plate materials to be joined. The process of sandwiching the above material as an insert material between the panels can be omitted, and not only the work efficiency is improved by reducing the processing man-hours, but also the plating layer melted by the eutectic reaction together with the surface impurities around the joints. After being discharged, an extremely clean new surface appears from under the plating layer, and a stronger bond is possible.

  For example, when joining a dissimilar metal panel made of a light alloy panel such as an aluminum alloy material or a magnesium alloy material and a steel material, zinc, which is a fourth metal that forms a low melting point eutectic with aluminum or magnesium, is used as the steel material. Can be used a so-called galvanized steel sheet whose surface is pre-plated. In this case, it is possible to use a normal commercial steel material that has been galvanized for the purpose of rust prevention as it is without any new plating or special preparation. This makes it possible to perform strong bonding of dissimilar metal panels.

Here, an example of an Al—Zn alloy will be described for eutectic melting.
FIG. 4 shows an Al—Zn-based binary phase diagram. As shown in the figure, the eutectic point (Te) in the Al—Zn system is 655 K, which is much lower than the melting point of Al 933 K. A eutectic reaction occurs at temperature.
Therefore, by using the eutectic points shown in the figure to create eutectic melting of Al and Zn, and using them for bonding effects such as oxide film removal and interdiffusion during bonding of aluminum materials, low temperature bonding can be performed. The growth of intermetallic compounds at the bonding interface can be extremely effectively suppressed.

Here, eutectic melting means melting utilizing a eutectic reaction, and when the composition of an interdiffusion region formed by mutual diffusion of two metals (or alloys) becomes a eutectic composition, a holding temperature. If is equal to or higher than the eutectic temperature, a liquid phase is formed by the eutectic reaction. For example, in the case of aluminum and zinc, the melting point of aluminum is 933 K and the melting point of zinc is 692.5 K, whereas this eutectic metal melts at 655 K, which is lower than the respective melting points.
Therefore, a reaction occurs when the clean surfaces of both metals are brought into contact and heated to 655K or higher. This is called eutectic melting, and Al-95% Zn has a eutectic composition, but the eutectic reaction itself is a constant change unrelated to the alloy components, and the alloy composition only increases or decreases the amount of eutectic reaction. Absent.

On the other hand, an oxide film exists on the surface of the aluminum material, and this is physically destroyed by plastic deformation of the aluminum material due to heating by irradiation with a high energy beam and pressurization at a predetermined temperature immediately after that. Will be.
That is, microscopic projections on the surface of the material rub against each other by pressurization, so eutectic melting occurs from the part where aluminum and zinc contact due to local destruction of some oxide films, and this liquid phase is generated. By accelerating the reaction in which the nearby oxide film is crushed and decomposed and further eutectic melting spreads over the entire surface, the destruction of the oxide film and the joining via the liquid phase are achieved.

  Since the eutectic composition is spontaneously achieved by interdiffusion, composition control is not necessary. The essential condition is that a low melting eutectic reaction exists between the two metals or alloys. In the case of eutectic melting of aluminum and zinc, when using Zn-Al alloy instead of zinc, The composition must be at least 95% zinc.

FIGS. 5A to 5E are schematic views showing an example of joining a galvanized steel sheet (high melting point metal panel) and an aluminum alloy sheet (low melting point metal panel) as a joining process of dissimilar metal panels according to the present invention. is there.
First, as shown in FIG. 5A, a galvanized steel sheet 1 provided with a galvanized layer 1p functioning as a third metal material that forms a eutectic with Al on at least the surface on the bonding interface side, and aluminum An alloy material 2 is prepared, and as shown in FIG. 5B, the galvanized steel sheet 1 and the aluminum alloy material 2 are overlapped so that the galvanized layer 1p is on the inside. An oxide film 2 c is generated on the surface of the aluminum alloy material 2.

  Next, when the galvanized steel sheet 1 is irradiated with a high energy beam and the joining interface reaches a predetermined temperature range, both panels are pressurized and the joining surfaces are relatively pressed, so that plastic deformation and thermal shock are caused by the pressing. As a result, the oxide film 2c is locally broken at the microscopic contact portion of the material surface as shown in FIG.

  As a result, local contact between zinc and aluminum occurs, and depending on the temperature state at that time, as shown in FIG. 5 (d), eutectic melting of zinc and aluminum occurs, which is oxidized together with the eutectic molten metal Me. A discharge material composed of the film 2c and impurities at the bonding interface is discharged to the outside (in the direction of the arrow) of the bonded portion, so that a predetermined bonded area is secured. As a result, as shown in FIG. The new surfaces of the alloy material and the steel material are directly joined by the extremely thin reaction layer L, and a strong metal joint between the steel plate 1 and the aluminum alloy material 2 is obtained. Although a thin diffusion layer of zinc to steel may occur between the reaction layer L and the steel material 1 depending on the material and joining conditions, there is little influence on the joining strength and there is no substantial problem.

As a specific combination of the plate materials in the joining method of different metals of the present invention, for example, a combination of a steel material and an aluminum alloy material can be mentioned. At this time, a fourth material interposed between the two materials is an aluminum alloy. As long as it is a material that forms a low melting point eutectic, there is no particular limitation. For example, in addition to zinc (Zn), copper (Cu), tin (Sn), silver (Ag), nickel (Ni) or the like can be used.
That is, the eutectic metal of these metals and Al melts below the melting point of the aluminum alloy material, which is the base material, so that even when joining steel materials and aluminum alloy materials where fragile intermetallic compounds are easily formed, oxidation occurs at a low temperature. The film can be removed, the formation of intermetallic compounds at the bonding interface during the bonding process can be suppressed, and strong bonding becomes possible.

Moreover, when considering the application of the joining method of the present invention to the assembly of an automobile body, the material of the panel to be joined is mostly a combination of steel and aluminum, but in the future, steel and magnesium or aluminum A combination with magnesium is also conceivable.
When joining a steel panel and a magnesium panel, it is possible to cause a eutectic reaction between zinc and magnesium plated on the steel side in the same manner as in the examples described later. Furthermore, when joining an aluminum panel and a magnesium panel, it is possible to utilize zinc or silver as the fourth material.

  In the present invention, the fourth material is not necessarily limited to the pure metal as described above, and eutectic metal includes both binary alloys and ternary alloys, and therefore, at least one of these metals. An alloy containing may be used.

Therefore, in the explanatory view shown in FIGS. 1 to 3, by using a galvanized steel plate as the first plate member 1 and the third plate member 3, strong dissimilar material joining by using a eutectic reaction is more easily performed. be able to.
That is, the laser beam B is irradiated from the side of the third plate 3 to the position immediately above the long hole 2a, and the third plate 3 is melted down as shown in FIG. The plate material 3 and the plate material 1 are melt-bonded, and the periphery of the melt-bonded portion is pressed by the pressure roller 10 as shown in FIG.

The second plate member 2 is heated by heat transfer from the melt-bonded portion of the plate member 3 and the plate member 1, and the interface between the first plate member 1 and the second plate member 2, and the interface between the third plate member 3 and the second plate member 2. Is maintained at a predetermined temperature at which eutectic reaction occurs and is maintained at a predetermined pressure by the pressure roller 10, eutectic melting of zinc and aluminum occurs, and an oxide film, impurities, etc. together with the eutectic molten metal Is smoothly discharged from the bonding interface, the new surfaces of the plate members are directly bonded to each other at the bonding portions 4 and 5, and the first and third plate members 1 and 3 and the second plate member 2 (aluminum alloy material) A strong metal bond can be obtained.
The pressure surface 10a of the pressure roller 10 is desirably provided with a curved surface having an appropriate curvature, which improves the discharge performance from the bonding interface such as an oxide film or a eutectic reaction product. Can be made.

  For example, as shown in FIG. 6 (a), a melt bonding portion between the plate material 3 and the plate material 1 using two pressure rollers 11 having a pressure surface, that is, a contact surface with the third plate material 3 is convex. The pressure roller 12 having a shape such that two pressure rollers 11 are connected to each other as shown in FIG. It is desirable to pressurize both side portions, and by using the roller 11 or 12 having such a cross-sectional shape, by giving a pressure distribution such that the central portion is high at the portion to be pressed, the high melting point material is used. The eutectic molten metal and the like can be efficiently discharged from the bonding interface between the plate materials 1 and 3 and the plate material 2 made of a low melting point material, so that sound and high strength bonding is possible.

Furthermore, as shown in FIG. 7, it is also desirable to form protrusions 1b and 3b that are convex toward the second plate 2 on the first and third plates 1 and 3 made of a high melting point material. That is, by providing such projections 1b and 3b in advance on the plate material and giving the pressure distribution such that the central portion is high at the part to be pressed, eutectic molten metal or the like from the joint interface is similarly obtained. Emission can be increased.
By joining in the above procedure, it becomes possible to join the three plate materials at a high efficiency at a time.

  Hereinafter, the present invention will be specifically described based on examples. In addition, this invention is not limited only to these Examples.

Example 1
FIG. 8 shows an example in which the dissimilar metal joining method of the present invention is applied to the roof structure of an automobile body, and is a cross-sectional view showing the joining procedure.
As shown in the drawing, a steel rail inner 11 (plate thickness: 1.4 mm), a rail outer 12 (plate thickness: 0.8 mm), and a side outer 13 (plate thickness: 0.8 mm) were assembled by welding. A roof panel 21 (plate thickness: 1.0 mm) made of a 6000 series aluminum alloy is stacked from above the vehicle body member.

The side outer 13 of the vehicle body member is provided with a joining surface 13a, and a joining flange 21a formed at the end of the roof panel 21 is overlapped with this part.
Further, a steel retainer 31 (plate thickness: 0.8 mm) is overlaid on the joining flange 21a of the roof panel 21 (second member).

  Then, the laser beam B focused on the surface of the retainer 31 is irradiated in a stitch shape from the retainer 31 side.

As the laser beam B, an Nd: YAG laser is used. Regarding the irradiation conditions, the surface of the retainer 31 is irradiated with the laser beam, and both the retainer 31 and the joining flange 21a of the roof panel 21 are penetrated and melted. The laser defocus diameter, the laser output, and the feed rate were set so that a part of 13 was melted.
Specifically, using a laser oscillator with a maximum output of 3 kW and a lens with a focal length of 150 mm, the focal point is adjusted so that the focus is just on the surface of the retainer 31, and the laser output is 2.0 kW and the feed rate is 0.7 to 1. Irradiation was performed at 0.0 m / min. During laser irradiation, argon gas was flowed at a flow rate of 25 L / min to shield the joint.

  At this time, the laser beam B is configured to be movable relative to the vehicle body member. While moving the laser beam B along the joining flange 21a of the roof panel 21, the vehicle body member is viewed from the retainer 31 side. , The molten portion passes through the joining flange 21a of the retainer 31 and the roof panel 21, reaches a part of the side outer 13 of the vehicle body member, and sandwiches the joining flange 21a of the roof panel 21 so as to sandwich the retainer 31. And the side outer 13 are melt-bonded, and the roof panel is fixed to the side outer 13.

(Example 2)
9 and 10 show an example in which the dissimilar metal joining method of the present invention is applied to the roof structure of an automobile body. FIG. 9 is a perspective view showing the joining structure of the car body, and FIG. It is sectional drawing which shows the junction point.
As shown in the figure, the steel rail inner 11 (plate thickness: 14 mm), rail outer 12 (plate thickness: 0.8 mm), and side outer 13 (plate thickness: 0.8 mm) were assembled by welding. A roof panel 22 (plate thickness: 1.0 mm) made of a 6000 series aluminum alloy is stacked from above the vehicle body member.
The side outer 13 of the vehicle body member is provided with a joining surface 13a, and a joining flange 22a formed at the end of the roof panel 22 is overlapped on this portion. The joining flange 22a has a long hole 22b (through hole). It is open intermittently.

Further, a steel retainer 31 (plate thickness: 0.8 mm) is overlaid on the joining flange 21a of the roof panel 22 (second member).
The side outer 1 (first plate material) 3 and the retainer 3 (third plate material) 1 are made of commercially available galvanized steel sheets whose surfaces are galvanized.

  Immediately after irradiating the surface of the retainer 31 with a laser beam B along the surface of the retainer 31 along the position of the elongated hole 22b formed intermittently in the joint flange 22a of the roof panel 22, The pressure roller 10 presses the joining flange 22a of the retainer 31 and the roof panel 22 in a direction in which the position is pressed against the side outer 13 of the vehicle body member.

As the laser beam B, an Nd: YAG laser is used. As for the irradiation conditions, the surface of the retainer 31 is irradiated with the laser beam, and the retainer 31 and the side outer 13 of the vehicle body member are melt-bonded. Based on heat transfer and pressure applied by the pressure roller 10, the laser is heated to a temperature above which eutectic melting occurs at the joint interface where the roof panel 22 made of aluminum alloy, the side outer 13 made of galvanized steel and the retainer 31 are in close contact. The defocus diameter, laser output, and feed rate were set.
Specifically, using a laser oscillator with a maximum output of 3 kW and a lens with a focal length of 150 mm, the focus is adjusted so that the focus is just on the surface of the retainer 31, and the laser output is 1.0 kW and the feed rate is 0.7 to 1. Irradiation was performed at 0.0 m / min. During laser irradiation, argon gas was flowed at a flow rate of 25 L / min to shield the joint.

At this time, the laser beam B and the pressure roller 10 are configured to be relatively movable with respect to the vehicle body member. First, the laser beam B is intermittently opened on the joining flange 22a of the roof panel 22. When irradiating the body member from the side of the retainer 31 while moving along the long hole 22b, the retainer 31 and the side outer 13 are melt-bonded through the long hole 22b of the joining flange 22a (see FIG. 2B). .
Following this, the joining flange 22a of the roof panel 22 is pressed against and brought into close contact with the joining surface 13a of the side outer 13 by the pressure of the pressure roller 10, and from the fusion joining portion of the retainer 31 and the side outer 13 Due to this heat transfer, the periphery of the long hole 22b formed in the joining flange 22a is heated, and the joining interface between the retainer 31 and the joining flange 22a and the joining interface between the side outer 13 and the joining flange 22a are brought to a temperature at which a eutectic reaction appears. Since it is held and pressed by the pressure roller 10, eutectic melting occurs at the bonding interface as shown in FIGS. 5A to 5E, and the eutectic molten metal becomes an oxide at the interface. As a result of being smoothly discharged from the joint interface together with other products, no intermetallic compound is generated, and the roof panel 21 and Outer 13, roof panel 22 and the retainer 31 are joined in the vicinity of the melting joint.

  Here, compared with the rigidity of the joining flange 22a of the retainer 31 and the roof panel 22 made of aluminum alloy, the rigidity of the vehicle body member, which is a steel structural member, is sufficiently high. Compared to the case of joining with rivets R as shown in FIG. 11, since the presser T from the vehicle interior side is not required, the joining position and structure of the roof panel 22 and the vehicle body member can be set relatively freely. Since the degree of freedom is high and the width of the joining flange can be narrower than that of rivet joining, the appearance quality as a vehicle body is improved.

It is a figure explaining the joining point of the dissimilar metal by this invention, Comprising: It is the side view seen from the direction orthogonal to a joining line. (A)-(c) is each sectional drawing about the cutting lines a, b, and c in FIG. (A)-(c) is each sectional drawing about the cutting lines a, b, and c in this invention. It is a graph which shows the eutectic point in an Al-Zn type binary phase diagram. (A)-(e) is process drawing which shows roughly the joining process of the dissimilar-metal panel which interposed the 3rd material. (A) And (b) is explanatory drawing which shows the embodiment of a pressure roller. It is explanatory drawing which shows the example of embodiment which formed the protrusion in the 1st and 3rd board | plate material. It is sectional drawing which shows the joining procedure of the steel vehicle body member and aluminum roof panel by the 1st Example of this invention. It is a perspective view which shows the joining structure of the steel vehicle body member and aluminum roof panel by the 2nd Example of this invention. FIG. 10 is a cross-sectional view showing a joining procedure of the steel vehicle body member and the aluminum roof panel shown in FIG. 9. It is a schematic sectional drawing which shows the example of a joining structure by the rivet of a steel vehicle body member and an aluminum roof panel.

Explanation of symbols

1, 13 First plate (steel plate, galvanized steel plate: high melting point material)
1a Protrusion 1p Zinc plating layer (4th material)
2, 21, 22 Second plate material (aluminum alloy material: low melting point material)
2a, 22b Long hole (through hole)
3, 31 Third plate (steel plate, galvanized steel plate: high melting point material)
3a protrusion B Laser beam (high energy beam)

Claims (8)

When a first plate made of a high melting point material and a second plate made of a low melting point material are overlapped and a high energy beam is irradiated from the side of the second plate, the two plate members are overlapped. a through hole in the stitch-shaped and formed in at least one of the further second plate the first plate member and the overlapping third plate made of refractory material of the same type Rutotomoni, the first and the third plate After the projection is fitted into the through hole of the second plate member, the first plate member and the third plate member are intermittently melt-bonded through the through hole by the high energy beam irradiated to the third plate member. After that, the dissimilar metal joining method characterized by pressurizing the vicinity of the melt joint. It said interposed different fourth material between the first and third plate and these materials during a second plate, by irradiation and the pressure of the high-energy beam, the first and third plate and the second A part of the oxide film of the plate material is broken and brought into local contact with the fourth material, and eutectic melting generated between the fourth material and the fourth material is expanded from the contact portion as a starting point. Destroying the oxide film at the bonding interface between the plate material and the second plate material, removing the oxide film together with the eutectic molten metal from the bonding interface, and bonding the first and third plate materials to the second plate material. The method for joining dissimilar metals according to claim 1 , characterized in that: The method for joining dissimilar metals according to claim 2 , wherein plating with a fourth material is performed on at least one of the first and third plate members and the second plate member. The dissimilar metal joining method according to claim 3 , wherein the first and third plate members are galvanized steel plates, and zinc plated on the galvanized steel plates is used as a fourth material. . 5. The method for joining dissimilar metals according to claim 4 , wherein the second plate material is made of an aluminum alloy. In pressurizing the molten bonding vicinity of the plate material, applying plane with two rollers forming a convex, any one of the claims 2-5, characterized in that pressurizing the sides of the melted joint The joining method of the dissimilar metals as described in the item. 3. When pressurizing the vicinity of the melt-bonded portion of the plate material, both sides of the melt-bonded portion are pressed using a roller formed by integrating two rollers whose pressurizing surfaces are convex . 6. The method for bonding dissimilar metals according to any one of 5 above. The curved surface which protrudes in the 2nd board | plate material side is provided in the joint surface with the 2nd board | plate material in the said 1st and 3rd board | plate material, The statement of any one of Claims 2-7 characterized by the above-mentioned. Dissimilar metal joining method.

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