JP2008000754A - Method and structure of joining different kinds of metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of joining different metals by which the corrosion (electric corrosion) caused by contact of the different metals is prevented and a different material joint excellent in corrosion resistance and bonding strength is obtained in a member which is composed by joining the different metals, and to provide a joining structure by such a method. <P>SOLUTION: When superimposing and joining the different metals, welding is performed in the state where a sealant 5 is arranged so as to encircle the predetermined joining part 1a between the different metal materials 1, 2. At this time, desirably, after forming a recessed part 3a or a projecting part 4a so as to encircle the predetermined joining part 1a on the joint surface of the material 1, the sealant 5 is arranged around the recessed part 3a or the projecting part 4a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for joining dissimilar materials made of metals having different ionization tendencies and a dissimilar metal joining structure obtained by such a method.

  For example, steel materials have been widely used for automobile bodies, but in addition to this, in recent years, the use of light metals such as aluminum alloys has been promoted for the purpose of reducing the weight of automobile bodies, and formed of aluminum alloys and the like. The applied vehicle body member (for example, an aluminum alloy roof panel) is applied to the vehicle body.

It is known that when different kinds of metals as described above are used in combination at the joint portions of these members, the different kinds of metals come into contact with each other and are electrically connected to accelerate corrosion.
Corrosion due to contact of different metals is considered to occur when a potential difference occurs between these metals due to the difference in the ionization tendency of the metals, and a corrosion current flows. Conventionally, in order to prevent corrosion due to different metal contacts, The following measures are known.

That is, in Patent Document 1, for example, a first member made of steel and a second member made of aluminum or an alloy thereof, for example, with a sealant interposed between the two members, for example, a rivet or a reinforcing member There has been proposed a joining structure for vehicle body members that is joined by the joining means.
In Patent Document 2, a member in which an iron-based material and aluminum or an aluminum alloy material are bonded is immersed in a solution containing a fluoro complex ion and zinc ion, and a dense, strong, and adhesive layer is formed in the vicinity of the bonded portion. It is described that metal zinc having a high ionization tendency between aluminum and iron is deposited, thereby improving the corrosion resistance of different metals at the joint.
JP 2000-272541 A JP 2005-154844 A

However, in the technique described in Patent Document 1, since the melting point and the linear expansion coefficient of both materials are different, it avoids fusion bonding such as spot welding and employs mechanical fastening such as rivets and bolts. There is a problem that the weight and cost of the joined members increase.
Further, in the technique described in Patent Document 2, the joined member is immersed in a solution containing a fluoro complex ion and zinc ion. However, only zinc deposited on the surface of the joining material is used for an automobile part. In addition to not being able to fully satisfy the required corrosion resistance performance, incorporating a process of immersing car body parts in such a solution during the production process of automobiles will lead to new capital investments such as immersion tanks. Necessary and cost increases.

  The present invention has been made in view of the above-mentioned problems in conventional dissimilar metal joining technology, and the object of the present invention is to prevent corrosion due to dissimilar metal contact and to be excellent in corrosion resistance and joint strength. It is an object to provide a joining method of dissimilar metals that can obtain a dissimilar material joint at low cost, and a joining structure by such a method.

  As a result of intensive investigations to achieve the above object, the present inventors have achieved the above object by interposing a sealing material in a portion other than the part where the joint between the different dissimilar metal materials is formed. The inventors have found that this can be solved, and have completed the present invention.

That is, the present invention is based on the above knowledge, and in the method for joining dissimilar metals according to the present invention, when materials composed of dissimilar metals are lap-joined, a portion to be joined is surrounded between the overlapped materials. As described above, the sealing material is arranged and then welded.
In addition, the dissimilar metal joining structure of the present invention is obtained by such a method, and is characterized in that a sealing material is interposed between the overlapped materials so as to surround the joining portion. To do.

  According to the present invention, when different metal materials are lap-joined, a sealing material is disposed between the two overlapped materials so as to surround a site to be joined, and welding is performed in this state. It is possible to produce a dissimilar metal joint excellent in corrosion resistance and bonding strength at low cost without contacting metals having different tendencies or leaving a sealing material at the joint.

  The dissimilar metal bonding method and bonding structure of the present invention will be described in more detail and specifically below.

  In the dissimilar metal bonding method according to the present invention, as described above, a portion to be bonded is surrounded between the overlapped dissimilar metal materials, in other words, a position where the bonding portion is formed is avoided and the periphery is sealed. Since the material is arranged and welded in a state where there is no sealing material at the joining site, it is possible to prevent the joint strength from being lowered due to the sealing material remaining at the joining interface, and to have different ionization tendency depending on the sealing material. Contact between each other can be prevented, and both strength and corrosion resistance can be achieved. At this time, it is not particularly necessary to add new equipment, and cost increase factors such as the cost of the sealing material and the number of man-hours for the sealing can be minimized.

In the joining method of the present invention, as the sealing material, for example, an epoxy resin-based material, a synthetic rubber-based material, a synthetic rubber / PVC-based material, or the like can be used. It can be applied to the surface or sandwiched between the two materials.
In this case, when applying the sealing material, it is necessary to apply the portion to be bonded to avoid joining the portion to be bonded, that is, the position where the bonding portion is formed. It is necessary to form a through hole in advance at the location to be performed.

In addition, as long as the objective of this invention can be achieved, it will not be limited to these.
Further, by using a material having an adhesive function for the sealing material, it is possible to improve the bonding strength in addition to the sealing effect for preventing electrolytic corrosion.

Further, in the joining method of the present invention, a convex portion protruding toward the joining surface is formed at the planned joining portion of the material to be joined, or the convex portion or the concave portion is surrounded on the joining surface of the joined material around the planned joining portion. It is desirable to form such protrusions and recesses on the joint surface in advance, thereby positioning the sealing material, controlling the coating amount, and positioning the sheet-like sealing material with through holes. This makes it easy to improve work efficiency and reduce man-hours.
In addition, as a shape of the convex part formed in the to-be-joined site | part of a to-be-joined material, it is desirable to provide the surface curved, for example in circular arc shape, and, thereby, the oxide film which intervenes in a joining surface, and various kinds produced in joining processes The discharge property of the reaction product and the like from the joint is improved, and a high-strength joint can be obtained.

  In the dissimilar metal joining method of the present invention, the welding method is not particularly limited, and includes not only fusion welding such as resistance welding, laser welding, and high frequency welding, but also friction stir welding, ultrasonic joining, diffusion joining, and the like. Various welding methods can be applied up to the solid phase bonding, and the method is not limited to the bonding method.

  The joining structure of dissimilar metals according to the present invention is such that a sealing material is interposed between the dissimilar metal materials overlapped so as to surround the joint, and can be obtained by the joining method of the present invention described above. And as described above, it has excellent corrosion resistance and strength.

In the joint structure of the present invention, the joint is made into a spot (spot) shape, and a concave portion or a convex portion is formed surrounding the dotted joint portion, and a sealing material is interposed around the concave portion or the convex portion. Compared to the structure that collectively encloses the plurality of point joints described below, the seal material can be disposed at a position closer to the joint part, so that higher waterproof and corrosion resistance can be exhibited. it can.
On the other hand, it is also possible to provide the above-described recesses or projections so as to surround the periphery of a plurality of adjacent point-like joints. In this case, the plurality of point-joint parts can be collectively blocked from the outside by a sealing material. As a result, work efficiency is improved.

  Furthermore, the joint portion is linear, and a concave portion or a convex portion is formed surrounding the linear joint portion, and a sealing material can be interposed around the concave portion or the convex portion, and is continuous. It is possible to achieve both excellent corrosion resistance and strength in wire bonding and intermittent wire (stitch) bonding.

In addition, the concave portion or the convex portion can be crushed and the sealing material interposed around the concave portion or the convex portion can be adhered to both materials. By adopting such a joint structure, the adhesiveness between the two materials, the joint portion, and the sealing material can be obtained. As a result, higher waterproofness and corrosion resistance can be exhibited.
Furthermore, the edge on the joint side of the recess formed around the joint can rise substantially perpendicular to the joint surface so that the sealing material does not enter the inside of the joint. No sealant remains at the joint interface, and the sealant can be located at a position close to the joint, so it can exhibit higher waterproofing and corrosion resistance, preventing strength reduction and excellent corrosion resistance It is possible to achieve both.

Hereinafter, the present invention will be specifically described based on examples. The present invention is not limited to these examples. For example, in the following examples, an example of joining an aluminum alloy and a galvanized steel sheet was shown. However, as a combination of different metals, in addition to the above combinations, electrolytic corrosion such as magnesium alloy and aluminum alloy, steel material and magnesium alloy, etc. It can be applied to all dissimilar metal joints in question.
In addition, as described below, the joining method such as resistance spot welding and resistance seam welding was used for spot joining, but the joining method is not limited to these. All the bonding methods that can be implemented are applicable.

  1 and 2 show the overall structures of a resistance spot welding device and a resistance seam welding device used in the embodiments of the present invention, respectively, where both are AC power supply type plates, A galvanized steel sheet 1 having a thickness of 0.55 mm and a 6000 series aluminum alloy sheet 2 having a thickness of 1.0 mm were joined.

(Example 1)
As shown in FIGS. 3 (a) and 3 (b), on the joining surface side of the galvanized steel sheet 1, the recess 3a is formed in a ring shape surrounding the planned joining portion 1a, and the outer portion excluding the inside of the recess 3a. Then, an epoxy resin adhesive was applied as the sealing material 5.
In addition, the inner edge W of the concave portion 3a on the planned joining portion side rises substantially perpendicular to the joining surface, and the seal material 4 does not penetrate into the concave portion 3a, that is, inside the planned joining portion 1a. It has become.

  Then, by superposing the aluminum alloy material 2 and applying a 24000 A alternating current for 0.24 seconds while applying a pressure of 300 kgf using the resistance spot welding apparatus shown in FIG. After spot welding at the site to be joined 1a, the portion projecting in a ring shape (the back side of the recess 3a) around the formed weld nugget 6 (joint) is crushed in the direction of the arrow, and the sealing material 5 is used as both materials. It was made to adhere to 1 and 2.

In this embodiment, the provision of the recesses 3a in the galvanized steel sheet 1 facilitates the positioning and application amount control when applying the sealing material 5 and improves the working efficiency. And by providing the recessed part 3a surrounding the circumference | surroundings of the point junction part 6, since the sealing material 5 can be arrange | positioned in the position close | similar to the junction part 6, higher waterproof and corrosion resistance performance could be exhibited.
In this case, since the edge W on the side close to the joining portion 6 stands substantially perpendicular to the joining surface, the sealing material does not enter and the sealing agent does not remain at the joining interface after joining. And since the seal | sticker 5 can be arrange | positioned in the position close | similar to the junction part 6 as mentioned above, the higher waterproof and corrosion resistance performance was able to be exhibited.

Further, by crushing the concave portion 3a provided surrounding the periphery of the joint portion 6 from the surface side and bringing the seal material 5 into close contact with the material to be joined 1 and 2, the material to be joined 1, 2 and the joint portion 6 and the seal material 5 As a result, it was possible to achieve higher waterproofness and corrosion resistance.
As a result, it was possible to achieve both the prevention of strength reduction due to the remaining sealing material at the joint interface and excellent corrosion resistance.

  In addition, in this Example, as shown in FIG.3 (b), although the example which formed the recessed part 3a surrounding the joining plan site | part 1a in the joining surface of the galvanized steel plate 1 was shown, FIG.3 (c) As shown in FIG. 5, it has been confirmed that the same effect can be obtained even if the galvanized steel sheet 1 is formed in a ring shape surrounding the part to be joined 1a with the convex part 4a protruding to the joining surface side.

(Example 2)
As shown in FIGS. 4 (a) and 4 (b), on the joining surface side of the galvanized steel sheet 1, the recesses 3b are formed in a rectangular shape surrounding a plurality of planned joining portions 1a (two places in the figure). The sealing material 4 similar to the above was applied to the outer portion excluding the inner side of the recess 3b.
Thereafter, as in the first embodiment, after both the materials 1 and 2 are spot-welded at the planned joining portion 1a, the protruding portion by the concave portion 3b is crushed from the surface side, and the sealing material 5 is similarly joined. The materials 1 and 2 were adhered.

  In this embodiment, the same effect as described above can be obtained, and since the recesses 3b are provided so as to surround the plurality of joints 1a, the plurality of joints 6 can be collectively blocked by the sealing material by the sealing material. Increased efficiency.

  In addition, it replaces with the said recessed part 3b, and as shown in FIG.4 (c), the convex part 4b which protrudes in the joining surface side is formed in the rectangular shape so that the some joining plan site | part 1a may be enclosed in the galvanized steel plate 1. It is also possible to do so.

(Example 3)
As shown in FIGS. 5 (a) and 5 (b), on the joining surface side of the galvanized steel sheet 1, a concave portion 3c is formed in a rectangular shape surrounding the linear joining planned portion 1a. The sealing material 4 similar to the above was applied to the outer portion excluding the inner side of the recess 3c.
Then, the aluminum alloy material 2 is overlapped, and a resistance seam welding apparatus shown in FIG. 2 is used, a constant pressure of 400 kgf is applied between both roller electrodes, and an alternating current of 30000 A is applied, and 1.8 m After seam welding the two materials 1 and 2 at the planned joining site 1a at a speed of / min, the back surface side of the recessed portion 3c protruding around the formed weld line 16 (joined portion) is crushed in the direction of the arrow and the sealing material 5 was adhered to both materials 1 and 2.

In this way, by forming the concave portion 3c into a long rectangular shape extending along the planned joining portion 1a so as to surround the joining planned portion 1a having a linear shape, the strength of the seam welding is reduced due to the remaining sealing material. It was possible to achieve both prevention and deterioration of corrosion resistance due to contact with different metals.
In place of the recess 3c, as shown in FIG. 5C, the same effect can be obtained even if the protrusion 4c protruding toward the bonding surface is formed in a rectangular shape surrounding the linear bonding planned site 1a. This is exactly the same as in the first and second embodiments.

Example 4
6 (a) and 6 (b) are explanatory views relating to a fourth embodiment of the present invention. Here, a hat-shaped cross-sectional member 1 made of a galvanized steel sheet having a thickness of 0.8 mm, and a thickness 1 An example is shown in which a 0.0 mm 6000 series aluminum alloy sheet 2 is spot-welded via a sheet-like sealing material 15.

As shown in FIG. 6 (b), arc-shaped convex portions 2a projecting toward the joining surface are respectively formed at the planned joining portions at both ends of the aluminum alloy sheet material 2, and a sealing material 15 having a sheet shape is formed. Is provided with a through-hole 15a in advance at the position to be joined, that is, at a position corresponding to the convex portion 2a.
Next, the sealing material 15 is placed on both ends of the aluminum alloy plate material 2 and aligned so that the convex portion 2a of the plate material 2 fits into the through hole 15a of the sealing material 15, and galvanized thereon. The flange part of the steel plate member 1 was overlapped.

Then, while applying a pressure of 300 kgf using a resistance spot welding apparatus as shown in FIG. 1, an alternating current of 20000 A is energized for 0.24 seconds, whereby both materials 1 and 2 are to be joined (projection) In 2a), each was joined by spot welding.
In this embodiment, by using a sheet-like material provided with through-holes 15a at a location corresponding to the site to be joined as the sealing material, the sealing material application step can be omitted, and only sandwiched between both materials, Corrosion resistance can be imparted to many joints at once. Further, the convex portion 2a makes it easy to position the sheet-like sealing material 15, and it is possible to achieve both the prevention of strength reduction due to the remaining sealing material and excellent corrosion resistance with high productivity.

By making the projecting surface of the convex portion 2a a gentle arc-shaped curved surface, a zinc-aluminum eutectic melt existing as a plating layer on the steel sheet surface, an oxide film of aluminum, and various other processes generated in the joining process As a result, the discharge property of the reaction product from the bonding interface is improved, and a stronger bonding becomes possible.
In addition, although the example which provided the convex part 2a in the joining surface of the aluminum alloy board | plate material 2 was shown here, you may provide a convex part in the steel material 1 side or both of these.

(Comparative example)
Using the galvanized steel sheet 1 and the aluminum alloy sheet 2 used in Example 1, spot welding was performed under the same conditions as in Example 1 without applying a sealing material to the joint surfaces (Comparative Example 1).
On the other hand, spot welding was performed under the same conditions in a state where the sealing material 5 was applied to the entire joint surface including the planned joining portion of the galvanized steel sheet 1 (Comparative Example 2), and these were compared. The results are shown in FIGS. 7 (a) and (b).

When bonded without applying a sealing material, as shown in FIG. 7A, a diffusion reaction layer D is formed at the bonded portion, and a zinc and aluminum eutectic melt around the plating layer is formed around the diffusion reaction layer D. E was observed, and a good bonding state was confirmed. However, a difference in ionization tendency between the two materials caused a potential difference between the two materials, and a corrosion current flowed to cause corrosion.
On the other hand, when bonded in a state where the sealing material 5 is applied to the entire bonding surface, although the penetration of water and the like is prevented and corrosion resistance is obtained, as shown in FIG. Since the sealing material 5 is only partially formed and remains at the bonding interface, the bonding strength is reduced. In both cases, the strength is prevented from being reduced due to the remaining sealing material at the bonding interface. In addition, it is impossible to realize both prevention of deterioration of corrosion resistance due to electric corrosion. Table 1 shows a comparison between these comparative examples and the performance of Example 1 of the present invention.

It is the outline which shows the structure of the resistance spot welding apparatus used for the Example of this invention. It is the outline which shows the structure of the resistance seam welding apparatus used for the Example of this invention. It is sectional drawing (c) at the time of forming a convex part instead of the top view (a), sectional drawing (b), and recessed part of the junction part obtained by Example 1 of this invention. It is sectional drawing (c) at the time of replacing with a top view (a), sectional drawing (b), and a recessed part of the junction part obtained by Example 2 of this invention. It is sectional drawing (c) at the time of replacing with the top view (a) of sectional part obtained by Example 3 of this invention, sectional drawing (b), and a recessed part, and forming a convex part. It is the perspective view (a) and sectional drawing (b) which show the junction point in the 4th Example of this invention. It is sectional drawing which shows the joining structure (a) obtained by welding without using a sealing material as a comparative example, and the joining structure (b) which apply | coated and welded the sealing material to the whole joining surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Galvanized steel plate 1a Joining part 2 Aluminum alloy material 2a Convex part 3a, 3b, 3c Concave part 4a, 4b, 4c Convex part 5,15 Seal material 6,16 Joint part 15a Through-hole

Claims (11)

  A method for joining dissimilar metals, characterized in that when a material composed of dissimilar metals is lap-joined, welding is performed in a state where a sealing material is disposed between the overlapped materials so as to surround a site to be joined.   The method for joining dissimilar metals according to claim 1, wherein a projecting portion is formed at a planned joining site on at least one joining surface of the both materials.   The method for joining dissimilar metals according to claim 2, wherein the convex portion has a curved surface.   2. The method for joining dissimilar metals according to claim 1, wherein a concave portion or a convex portion surrounding the portion to be joined is formed on at least one joint surface of the two materials.   The dissimilar metal according to any one of claims 1 to 3, wherein a sheet-like sealing material having a through-hole is interposed between the overlapped materials at a portion corresponding to the joint portion. Joining method.   It is a joining structure obtained by the method according to any one of claims 1 to 5, wherein a sealing material is interposed between the superposed materials so as to surround the joining portion. Metal junction structure.   7. The joint according to claim 6, wherein the joint has a dot shape, a recess or a projection is formed surrounding the spot joint, and a sealing material is interposed around the recess or the projection. Bonding structure of dissimilar metals.   7. The joint according to claim 6, wherein the joint is formed in a dot shape, and a plurality of dot joints are formed to form a recess or a projection, and a sealing material is interposed around the recess or the projection. The junction structure of the dissimilar metals described.   The said joining part comprises linear form, a recessed part or a convex part is formed surrounding this linear joined part, and the sealing material is interposing the said recessed part or convex part, It is characterized by the above-mentioned. Bonding structure of dissimilar metals.   The joint structure of dissimilar metals according to any one of claims 7 to 9, wherein the concave portion or the convex portion is crushed and a surrounding sealing material is in close contact with both materials.   The dissimilar metal according to any one of claims 7 to 10, wherein a concave portion is provided around the joint portion, and an edge on the joint portion side of the concave portion rises substantially perpendicular to the joint surface. Bonding structure.

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