JP2009000728A - Method and structure for joining different metals - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a different metal joining method capable of achieving both of the corrosion resistance by a sealant and prevention of degradation of the joint strength by a remaining sealant without increasing the weight of a joint or the cost by a new equipment investment, and a joining structure by the method. <P>SOLUTION: When performing the lap joining of lapped different metals 10, 20 while a sealant S is coated in a vicinity of a joining part 11 by applying high-energy beams B, the joining part 11 is joined by providing a sealant flow-in preventive means such as a bank part 13 having a shape rising in a projecting shape from a joining surface between a coating position 12 of the sealant S and the joining part 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for joining dissimilar metals such as a steel material and an aluminum alloy material, and more specifically, when dissimilar metal materials are joined to each other by irradiating with a high energy beam such as an electron beam or a laser beam. The present invention relates to a dissimilar metal joining method capable of achieving both prevention of corrosion due to metal contact and prevention of reduction in joining strength due to the presence of a sealing material, and a joining structure of dissimilar metals joined by such a method. .

  In recent years, for the purpose of reducing the weight of automobile bodies and the like, in addition to steel materials that have been widely used in the past, body members made of light metals such as aluminum alloys (for example, roof panels made of aluminum alloys) Application has been made.

It is known that when dissimilar metals are used in combination at the bonding sites in these members, the dissimilar metals come into contact with each other and are electrically connected, thereby promoting corrosion.
Corrosion due to the contact of different kinds of metals is caused by the difference in ionization tendency of the metals, causing a potential difference between the metals and causing a corrosion current to flow. Conventionally, in order to prevent such corrosion caused by contact between different kinds of metals, Such measures are known.

  For example, Patent Document 1 discloses a first member made of steel and a second member made of aluminum or an alloy thereof, with a sealing material interposed between the two members, such as a rivet or a reinforcing member. There has been proposed a joining structure for vehicle body members that is joined by 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. Proposals have been made to deposit metal zinc having a high ionization tendency that is intermediate between aluminum and iron, thereby improving the corrosion resistance of dissimilar metals at the joint.
JP 2000-272541 A JP 2005-154844 A

  However, in the technique described in Patent Document 1, since the melting points and the linear expansion coefficients of the two materials are different, mechanical fastening such as rivets and bolts is employed without performing welding, so that the materials are used for joining. There is a problem in that the weight and cost of the vehicle body member increase as the number of parts increases.

  Further, in the technique described in Patent Document 2, the joined member is immersed in a solution containing fluoro complex ions and zinc ions. Incorporating the step of immersing the body parts into the vehicle requires a new investment in equipment such as a dip tank, which increases the cost. Furthermore, it is difficult to sufficiently satisfy the corrosion resistance required for automobile parts only with zinc deposited on the surface of the bonding material.

  As described above, in joining different kinds of metal materials, it is essential to take measures against electrolytic corrosion to prevent corrosion due to contact with different kinds of metals, and therefore, a method of joining with a sealing material at the joining interface is conceivable. At this time, in the case of a welding method that can directly pressurize the welded portion, such as resistance spot welding, the sealing material sandwiched between the joint interfaces can be discharged from the joint interface by laser welding. In the case of bonding by irradiation with a high energy beam, it is structurally difficult to directly pressurize the position where the high energy beam is irradiated with a pressurizing means. Since a method is employed in which the pressure is applied immediately after heating with a pressure roller or the like, this method has a problem that the sealing material tends to remain at the bonding interface and the bonding strength is greatly reduced.

  The present invention has been made in view of the above-mentioned problems in conventional dissimilar metal bonding using a high-energy beam, and its object is to increase the weight of joints and increase costs due to new capital investment. In addition, it is an object of the present invention to provide a method for joining dissimilar metals that can ensure both the corrosion resistance of the sealing material and the prevention of a decrease in joint strength due to the remaining sealing material, and a joining structure using such a method.

  As a result of intensive studies to achieve the above object, the present inventors applied a seal material in the vicinity of the joint portion while avoiding the joint portion, and between the seal material application portion and the joint portion. In addition, the present inventors have found that the above problem can be solved by taking a means for preventing the seal material from flowing into the joint, and have completed the present invention.

  That is, the present invention is based on such knowledge, and in the dissimilar metal joining method of the present invention, a high energy beam is applied to the dissimilar metal material superposed in a state where a sealant is applied in the vicinity of the joint. Means to prevent the inflow of the sealing material, such as a bank or a groove, between the application position of the sealing material and the joint, A means is provided.

  Further, the dissimilar metal lap joint structure of the present invention is such that the superposed dissimilar metal materials are directly or intermittently directly joined at the joint, and have a convex shape or a stepped shape near the joint. A structure including a bank and a sealant interposed between the two materials on the anti-bonding side of the bank, or a groove formed in a concave shape near the joint, and the anti-bonding section of the groove between the two materials It is characterized by having a structure in which the sealing material interposed on the side flows into the groove.

  According to the present invention, since the inflow prevention means such as a convex or stepped bank portion or a concave groove portion is provided between the application position of the sealing material and the joint portion, both materials are overlapped. Even when the seal material is crushed and spread between the two materials in the lateral direction, the seal material can be prevented from flowing into the joint, and there is no rust preventive material at the joint interface. Therefore, stable bonding is possible, and it is possible to achieve both high bonding strength and ensuring corrosion resistance with a sealing material.

  Below, the joining method and joining structure of the dissimilar metals of this invention are demonstrated concretely and in detail based on drawing.

  1 (a) to 1 (c) show an example of a laser welding apparatus used in the present invention. The laser welding apparatus shown in FIG. 1 (a) is connected to a laser oscillator (not shown) and is dissimilar. Laser irradiation head 50 (laser irradiation) which irradiates metal beam, for example, aluminum alloy plate 10 and steel plate 20, which is a high melting point side material stacked on the upper side, with laser beam B defocused obliquely from the front side. 1 (b), which is a front view from the front side in the traveling direction at the position), and the laser irradiation head 50, together with the laser irradiation head 50, moves to the left in the figure and pressurizes the position immediately after the laser irradiation to join both materials. It is mainly composed of a roller 51 (see FIG. 1 (c) showing a front view at a pressure position). In the welding apparatus, continuous movement and laser irradiation are performed so that both materials are continuous. They are joined can, so that it is multi-point bonding-stitch bonding or spot by intermittently irradiated with a laser beam.

  In the present invention, the combination of dissimilar metal materials to be joined is not particularly limited, and a high energy beam such as a laser is irradiated from the high melting point material side to transfer heat from the high melting point material. Although both materials are joined, here, description will be continued by taking as an example the combination of an aluminum alloy plate and a steel plate as described above.

  FIG. 2 shows the first embodiment of the present invention. When the steel plate 20 is stacked on the aluminum alloy plate 10, the joint 11 is formed on the aluminum alloy plate 10, which is the lower melting point material. As a means for preventing the seal material S from flowing into the joint portion 11 at a position between the seal material and the application position 12 of the seal material, the ridge portion 13 rising from the joint surface and forming a convex shape is continuously formed along the joint line. On the other hand, a step 21 is continuously formed on the steel plate 20, which is a high melting point material, along the bank portion 13 provided on the aluminum alloy plate 10.

Next, after continuously applying the sealing material S along the bank portion 13 to the application position 12 of the sealing material of the aluminum alloy plate 10, the steel plate 20 is stacked on the aluminum alloy plate 10.
At this time, the sealing material S pressed in the thickness direction is crushed and spreads in the lateral direction, but the convex bank portion 13 prevents the sealing material S from spreading, and the sealing material S to the joint portion 11 is spread. Inflow can be prevented.

Then, the steel plate 20 is heated by irradiating the joint 11 while moving the laser beam B defocused from the side of the steel plate 20 along the joining line.
Then, immediately after the laser irradiation position is pressed by the roller 51 in the direction in which the steel plate 20 is pressed against the aluminum alloy plate 10, the steel plate 20 and the aluminum alloy are transferred by heat transfer from the steel plate 20 heated by the irradiation of the laser beam B. Since the joining interface of the joining portion 12 of the plate 10 is heated and maintained at a predetermined temperature and is also maintained at a predetermined pressure by the roller 51, the steel plate 20 and the aluminum alloy plate 10 are joined at the joining portion 11. become.

  After joining both the materials 10 and 20 by laser beam irradiation and pressurization by the roller 51, the sealing material S is continuously applied along the end portion to the right end portion of the steel plate 20 in the drawing. As a result, the overlapping portions of different metals are sealed from both sides by the sealing material S, and the water-tightness of the overlapping portions is maintained, so that it is possible to prevent electrolytic corrosion.

In this way, by forming the bank portion 13 between the joint portion 11 and the application position 12 of the sealing material, since the joining can be performed without the sealing material S at the interface of the joint portion, stable joining is possible and high. A joining strength is obtained, and a dissimilar material joint with high corrosion resistance is obtained.
As the sealing material S, a thermosetting resin adhesive is typically used. However, not only such an adhesive but also a two-component chemical reaction type adhesive or a solvent remains after the solvent is evaporated. It is also possible to use a solution-based adhesive that adheres when the solute is cured.

Here, as the shape of the bank portion, as shown in FIG. 3, the rising on the application position 12 side has a two-step shape, and a gap generated between the two materials when the mating joining materials are overlapped is a joining. It is desirable to use the bank portion 14 having a structure that becomes narrower toward the side closer to the portion 11.
That is, when the sealing material S made of a thermosetting resin enters a narrow gap on the side close to the joint portion 11, this portion of the sealing material S becomes thin and has a small volume. Since it can be easily heated to the curing temperature and can be cured quickly, when the material to be bonded is irradiated with a high energy beam B at the time of bonding, a seal having a small volume on the side closest to the bonding portion 11 due to heat transfer of the material. The material S can be locally cured continuously in a direction parallel to the joining line, and as a result, the seal material S can be prevented from flowing into the joining portion 11 more efficiently. Since the bonding can be performed without the sealing material S at the interface, stable bonding is possible and high bonding strength is obtained.

The shape of the bank portion as the inflow blocking means for preventing the seal material S from flowing into the joint portion 11 is not limited to the convex shape as described above, and the same effect can be exhibited by other shapes. Can do.
For example, as shown in FIG. 3, it can be set as the bank part 15 of the shape rising from a sealing material application surface, and also in this case, the bank part 15 was crushed like the above-mentioned embodiment example. The spreading of the sealing material S can be blocked to prevent the sealing material S from flowing into the joint portion 11.

Such a bank portion can exhibit the following derivative effects in addition to the above-described effect of preventing the inflow of the sealing material.
That is, since the bank portion 13 is provided continuously in parallel with the joining line, the bank portion 13 functions as a reinforcing bead as shown in FIG. Thus, the rigidity and strength of the member against bending in the joining line direction are improved.

Moreover, as shown in FIG. 6, since the step 21 along the bank 13 formed in the aluminum alloy plate 10 is continuously provided also on the side of the steel plate 20 covered from the upper side, When the 20 is overlapped, the vertical walls of the bank portion 13 and the step 21 are brought into contact with each other, so that the two plates to be joined can be easily positioned in the vertical direction and the tact time at the time of manufacture is reduced. Can contribute to reduction.
At the same time, due to the contact between the walls 13 and the vertical walls of the steps 21 in both materials 10 and 20, a tensile load was applied in a direction perpendicular to the joining line and parallel to the plate as shown in FIG. In this case, the load is applied between the vertical walls, and the load applied to the joint portion 11 is reduced. As a result, the strength of the joint can be improved.

In addition, when joining dissimilar metal materials, the linear expansion coefficients of the two materials are different, so when heat is applied to these materials, the difference in elongation between the two materials causes a shift between the materials, resulting in a shear force at the joint. However, as shown in FIG. 8, in the case of the combination of the steel plate 20 and the aluminum alloy plate 10, the elongation of the aluminum alloy plate 10 is larger than the elongation of the steel plate 20.
However, since the step 21 of the steel plate 20 presses down the vertical wall of the bank portion 13 of the aluminum alloy plate 10 and bears a load between the vertical walls, the shear force actually applied to the joint portion 11 is caused by the step 21 and the bank portion 13. Compared to the case where there is no, it is possible to make it smaller.

FIG. 9 shows an example in which a groove portion is formed in a material to be joined as means for preventing the seal material S from flowing into the joint portion 11 as another embodiment of the present invention.
That is, as shown in the figure, the aluminum alloy plate 10 is continuously formed along the joining line with a groove 16 that is recessed from the joining surface between the joining portion 11 and the application position 12 of the sealing material S. In addition, a groove 22 having a shape recessed from the joint surface is continuously formed on the side of the steel plate 20 at a position corresponding to the groove 16 of the aluminum alloy plate 10.

Next, after continuously applying the sealing material S along the groove portion 16 to the application position 12 of the sealing material in the aluminum alloy plate 10, the steel plate 20 is stacked on the aluminum alloy plate 10.
At this time, the sealing material S pressed in the thickness direction spreads in the lateral direction in the figure. However, since the moved sealing material S flows into the internal spaces of the groove portions 16 and 22 having a concave shape, the joint portion 11. It is possible to prevent the sealing material S from flowing into.

  And like the said each embodiment, while moving the laser beam B defocused from the steel plate 20 side, irradiating the joining part 11 and heating the steel plate 20, and pressurizing the roller 51 immediately after that, By the heat transfer from the steel plate 20 heated by the irradiation of the laser beam B, the steel plate 20 and the aluminum alloy plate 10 are joined at the joint 11. Furthermore, after joining both the materials 10 and 20, the sealing material S is continuously applied to the right end portion of the steel plate 20 in the drawing, so that the overlapping portions of different metals are sealed from both sides by the sealing material S, and overlapped. Since the water-tightness of the part is maintained, it is possible to prevent electrolytic corrosion due to contact with different metals.

  Thus, by forming the groove portions 16 and 22 between the joint portion 11 and the sealing material application position 12, it becomes possible to join without the sealing material S at the interface of the joint portion, and stable joining is achieved. Thus, a high joint strength can be obtained, and a dissimilar joint joint having high corrosion resistance can be obtained.

  FIG. 10 shows an example in which both a groove part and a bank part are formed in a material to be joined as a means for preventing the sealing material S from flowing into the joint part 11. As shown in FIG. The plate 10 has a groove 17 that is recessed from the joint surface and an embankment 18 that rises in a convex shape adjacent to each other between the joint 11 and the application position 12 of the sealing material S. In addition, on the side of the steel plate 20, a groove portion 22 having a shape recessed from the joint surface is continuously formed at a position corresponding to the bank portion 18 of the aluminum alloy plate 10.

Then, after continuously applying the sealing material S along the groove portion 17 to the application position 12 of the sealing material in the aluminum alloy plate 10, the steel plate 20 is stacked on the aluminum alloy plate 10.
At this time, since the groove portion 22 of the steel plate 20 is placed on the bank portion 18 of the aluminum alloy plate 10, the alignment of both plate materials becomes easy. Further, the sealing material S is crushed and spreads in the lateral direction in the figure, but the sealing material S flows into the concave groove portion 17 and is blocked by the bank portion 18. The inflow of the sealing material S to the portion 11 is prevented.

  Next, similarly, the steel plate 20 and the aluminum alloy plate 10 are joined at the joint portion 11 by heating by irradiation with the defocused laser beam B and pressurization by the roller 51 at a position immediately thereafter. Finally, the steel plate 20 By continuously applying the sealing material S to the end of the metal, the joining and sealing process of both metal materials is completed, and a dissimilar joint joint having both high joint strength and good corrosion resistance is obtained.

FIG. 11 shows, as still another embodiment of the present invention, an example in which the present invention is applied to the joining of a steel body member and a light alloy rule panel in an automobile roof structure. An aluminum alloy roof panel 34 is stacked from above a steel body member 30 in which a steel rail inner 31, a steel rail outer 32 and a steel side outer 33 are assembled by welding. The side outer 33 is provided with a joint portion 33a, and a joint flange 34a formed at the end of the roof panel 34 is overlapped with the joint portion 33a.

  Further, the side outer 33 is provided with a bank portion 33c formed in a step shape with respect to the joint surface as a sealing material inflow prevention means between the joint portion 33a and the sealing material application position 33b.

When joining the roof panel 34 made of aluminum alloy to the steel side outer 33, first, the sealing material S is continuously applied to the sealing material application position 33b of the side outer 33, and then the roof panel 34 is attached to the side outer 33. It overlaps with the joint part 33a.
At this time, the sealing material S crushed in the thickness direction spreads in the lateral direction. However, since the bank portion 33c formed in a step shape blocks the flow of the sealing material S, the sealing material S flows into the joint portion 33a. Can prevent

Here, the laser beam B and the pressure roller 52 are disposed so as to be relatively movable with respect to the vehicle body member 30. First, the laser beam B is moved along the joining flange 34 a of the roof panel 34. The portion exposed from the joining flange 34 a of the side outer 33 is irradiated to heat the side outer 33.
By doing so, the joint 33 a and the joint flange 34 a of the roof panel 34 are heated by heat transfer from the heated side outer 33.

  The joining flange 34a of the roof panel 34 is pressed against the joining portion 33a by the pressure applied by the roller 52, and is brought into close contact with the joining portion 33a, whereby the interface between the joining flange 34a and the joining portion 33a of the vehicle body member 30 is achieved. Is heated to a predetermined temperature and further pressurized by the roller 52, the joint flange 34a of the roof panel 34 and the joint portion 33a of the vehicle body member 30 are joined.

FIG. 12 shows another example of joining to the roof structure of an automobile composed of a steel material and an aluminum alloy material.
That is, the steel vehicle body member 30 includes a steel rail inner 31, a steel rail outer 32, and a steel side outer 35 that are similarly assembled by welding. Then, an aluminum alloy roof panel 36 is stacked.

A joint portion 35 a is set on the side outer 35 of the vehicle body member 30, and a joint flange 36 a that is an end portion of the roof panel 36 overlaps the joint portion 35 a.
The side outer 35 is provided with a bank portion 35c having a step shape with respect to the joint surface as a means for preventing the inflow of the seal material between the joint portion 35a and the application position 35b of the seal material.

In joining, first, the sealing material S is continuously applied to the application position 35b of the sealing material of the side outer 35, and then the roof panel 36 is overlaid on the joint 35a of the side outer 35.
When the roof panel 36 is piled up, the seal material S crushed by the pressure spreads in the lateral direction, but the flow of the seal material S is blocked by the bank portion 35c that rises in a step shape from the application surface, to the joint portion 35a. Inflow can be prevented.

Here, while moving the laser beam B along the joining portion of the roof panel 36 and the side outer 35, the side outer 35 is irradiated from the gap between the two, and the steel side outer 35 is heated. As a result, the joining portion 35 a and the joining flange 36 a of the roof panel 36 are heated by heat transfer from the heated side outer 35.
The joining flange 36a of the roof panel 36 is pressed and brought into close contact with the joining portion 35a of the side outer 35 by the pressure applied by the roller 53 arranged to follow the laser beam B, and the joining is performed by heat transfer from the joining portion 35a. When the interface between the flange 36a and the joint portion 35a of the vehicle body member 30 is heated to a predetermined temperature and further applied with pressure by the roller 53, the joint flange 36a of the roof panel 36 and the vehicle body member 30 are joined at the joint portion 35a. become.

As mentioned above, although the joining of the dissimilar metal which consists of an aluminum alloy plate and a steel plate has been demonstrated, this invention is not limited to these form examples.
For example, the combination of dissimilar metals is not limited to an aluminum alloy plate and a steel plate, but can be applied to various combinations where there is a concern about electrical corrosion due to contact of dissimilar metals. In addition, the present invention can be applied to stitch-like joining and multi-point spot joining. In addition to the cylindrical roller, various forms can be considered as the pressing means, and various applications are possible within the basic concept of the present invention.

It is a schematic explanatory drawing which shows the structural example of the laser welding apparatus used for this invention. It is sectional explanatory drawing which shows embodiment of this invention which formed the bank part as an inflow prevention means of a sealing material. It is sectional explanatory drawing which shows embodiment by the other example of a shape of a bank part. It is sectional explanatory drawing which shows embodiment by the example of another shape of a bank part. It is a schematic explanatory drawing which shows the other effect in the dissimilar material joint shown in FIG. It is a schematic explanatory drawing which shows the further another effect in the dissimilar material joint shown in FIG. It is a schematic explanatory drawing which shows another effect in the dissimilar material joint shown in FIG. It is a schematic explanatory drawing which shows another effect in the dissimilar material joint shown in FIG. It is sectional explanatory drawing which shows embodiment which formed the groove part as an inflow prevention means of a sealing material. It is sectional explanatory drawing which shows embodiment which formed both the groove part and the bank part as an inflow prevention means of a sealing material. It is sectional explanatory drawing which shows the example applied to the roof structure in a motor vehicle body as embodiment of this invention. It is sectional explanatory drawing which shows the other example of application to the roof structure in a motor vehicle body as embodiment of this invention.

Explanation of symbols

10 Aluminum alloy sheet steel (dissimilar metal material)
DESCRIPTION OF SYMBOLS 11 Junction part 12 Application | coating position of sealing material 13, 14, 15, 18 Bank part 16, 17 Groove part 20 Steel plate (dissimilar metal material)
22 Groove B Laser beam (High energy beam)
S sealing material

Claims (6)

  When dissimilar metal materials that are superposed with a sealant applied in the vicinity of the joint are irradiated with a high energy beam to join both materials together, the sealant A method for joining dissimilar metals, characterized by comprising inflow blocking means for preventing inflow into the joint.   The dissimilar metal joining method according to claim 1, wherein the inflow blocking means is a bank portion having a convex shape or a stepped shape with respect to the joining surface.   The method for joining dissimilar metals according to claim 1 or 2, wherein the inflow blocking means is a groove portion recessed in a concave shape with respect to the joining surface.   The said sealing material consists of thermosetting resins, and the said bank part is equipped with the multistage shape, The joining method of the dissimilar material of Claim 2 characterized by the above-mentioned.   The superposed dissimilar metal materials are directly or intermittently directly joined at the joint, and provided with a convex or stepped bank in the vicinity of the joint, and the opposite of the bank between the two materials is provided. A lap joint structure of dissimilar metals, characterized in that a sealing material is interposed on the joint side.   Overlapping dissimilar metal materials are directly or intermittently directly joined at the joint, and are provided with a concave groove in the vicinity of the joint, and are interposed on the anti-joint side of the groove between the two materials. A lap joint structure of dissimilar metals, wherein a sealing material flows into the groove.

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