JP2023100531A - Dissimilar material joining method - Google Patents

Abstract

To provide a dissimilar material joining method that ensures a sufficient strength while suppressing an increase in cost of manufacture even if a metal plate with a through hole is joined.SOLUTION: A rivet 30 comprising a shade part 31 and a shank 33, an aluminum plate 40 having a through hole 40a with a diameter larger than the shaft 33 and iron plates 50, 60, an upper electrode 3 and a lower electrode 5 are prepared. The method includes: a process in which the rivet 30 of which the shank 33 is inserted in the through hole 40a, and the aluminum plate 40 and the iron plates 50, 60 are pinched between the upper electrode 3 and the lower electrode 5 so that the shade part 31, the aluminum plate 40 and the iron plate 50 are arranged in this order; and a pressurization and electric conduction process in which the rivet 30, and the aluminum plate 40 and iron plates 50, 60 are pressurized and electrically conducted. In the pressurization and electric conduction process, electric conduction is conducted at a high current value and in a short time so that a nugget 71 is generated between the shank 33 and the iron plate 50, and a clearance C between the shank 33 and the through hole 40a is filled.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a method for joining dissimilar materials, and more particularly to a method for joining a plurality of metal plates by resistance welding using rivets.

BACKGROUND ART Conventionally, a dissimilar metal joining method is known in which dissimilar metal members are joined by resistance welding using a metal rivet having a cap portion and a shaft portion. In this method of joining dissimilar materials, for example, a rivet, an aluminum plate and an iron plate are sandwiched between two electrodes so that the cap portion, the shaft portion, the aluminum plate and the iron plate are arranged in this order, and the aluminum plate is pressed and energized. By creating a nugget between the shaft penetrating through and the iron plate, and sandwiching the aluminum plate between the cap and the iron plate, the aluminum plate and the iron plate, which are difficult to weld, are joined.

By the way, for example, if the aluminum plate and the iron plate are separated due to imperfect joining, after removing the old rivet, insert a new rivet into the hole formed by the rivet penetrating during the initial joining. It is known to perform repair (re-welding) by Then, during such re-welding, since the through-holes have already been formed in the aluminum plate, it is only necessary to form a nugget between the rivet and the iron plate, so normal iron spot welding conditions ( A relatively low current value) is generally applied.

However, in re-welding using such normal iron spot welding conditions, there is a gap between the aluminum plate (more precisely, the wall surface that defines the through hole) and the inserted rivet, so the strength is not sufficient. There is a problem that it becomes difficult to secure

Here, although it does not relate to re-welding, for example, Patent Document 1 describes a method for fixing a part having a hole formed thereon to a basic part by means of a bolt so that the tip surface of the bolt inserted into the hole is basically A technique is disclosed in which electric welding is applied to the surface of a component, and the shaft portion of the bolt softened by heating is crushed (plastically deformed so as to swell in the direction perpendicular to the axis) to fill the gap with the hole.

JP-A-2008-538232

If the technique of Patent Literature 1 is applied to re-welding, the collapsed shaft fills the gap between the aluminum plate and the rivet (bolt), so it seems possible to secure strength.

However, in the method of Patent Document 1, the plastic deformation of the shaft requires a separate reinforcing rivet to fill the gap between the aluminum plate and the rivet, which increases the manufacturing cost. There is

In addition, such a problem is not limited to re-welding when joining failure occurs, but also applies to joining metal plates that originally have a through hole with a larger diameter than the outer diameter of the shaft of the rivet. is.

The present invention has been made in view of this point, and its object is to ensure sufficient strength while suppressing an increase in manufacturing cost even when joining metal plates having through holes. To provide a dissimilar metal joining method capable of

In order to achieve the above object, in the method for joining dissimilar materials according to the present invention, a nugget is formed by applying a high current value for a short period of time without separately preparing a reinforcing rivet. I'm trying to fill the gap between

Specifically, the present invention is directed to a dissimilar metal joining method for joining a plurality of metal plates, including metal plates made of different metal materials, by resistance welding using rivets.

In this dissimilar material joining method, a metal rivet having a cap portion and a shaft portion and a through hole having a diameter larger than the outer diameter of the shaft portion of the rivet are formed of a metal material different from that of the rivet. A plurality of metal plates including a first metal plate and a second metal plate made of the same metal material as the rivet, and first and second electrodes are prepared; and the second metal plate are arranged in this order, the rivet having the shaft portion inserted into the through hole and the plurality of stacked metal plates are connected to the first electrode and the second metal plate. and a pressurization energization step of pressurizing and energizing the rivet and the plurality of metal plates by the first and second electrodes, wherein the pressure energization step includes the shaft portion and the second metal plate, and the first metal plate melts so that the gap between the shaft portion and the through hole is filled by melting the first metal plate. It is characterized in that current is supplied for a short period of time at a current value which is approximately the same as the current value required to pass through the shaft portion.

According to this configuration, when the shank of the rivet inserted in the through-hole and the second metal plate are welded together, the current value is approximately the same as the current value required to pass the shank through the first metal plate. In other words, since the energization is performed at a current value higher than that of a normal iron spot, not only a nugget is generated between the shaft portion and the second metal plate, but also the first metal The gap between the shaft and the through hole can be filled by melting the plate.

In this way, by applying current at a high current value, it is possible to fill the gap between the shaft and the through-hole without separately preparing a reinforcing rivet. can be sufficiently secured.

In addition, since the energization at a high current value is kept for a short period of time, the volume expansion of the molten first metal can be suppressed by the cap portion of the rivet, so the molten first metal is released. burrs can be suppressed.

As described above, according to the method for joining dissimilar materials according to the present invention, it is possible to sufficiently ensure strength while suppressing an increase in manufacturing cost even when joining metal plates having through holes.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which illustrates typically the outline|summary of the dissimilar material joining method which concerns on embodiment of this invention. FIG. 2(a) is a diagram schematically showing a main part of a resistance welding apparatus, and FIG. 2(b) is a diagram schematically showing an energization pattern in a method for joining dissimilar materials. FIG. 3(a) is a diagram schematically showing a general energization pattern, and FIG. 3(b) is a diagram schematically explaining a case where a high current is applied for a long period of time. It is a graph diagram which shows typically the test result of a shear strength. It is a figure explaining typically the correspondence at the time of the conventional joint failure. It is a figure which illustrates typically an example of the conventional method of joining dissimilar materials.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated based on drawing. 1 to 6, the rivet 30, the aluminum plate 40, the iron plates 50 and 60, etc. are shown in cross-sectional views for the sake of clarity.

-Device configuration-
FIG. 1 is a diagram schematically explaining the outline of the method for joining dissimilar materials according to this embodiment. FIG. 2(a) is a diagram schematically showing the main part of the resistance welding apparatus 1, and FIG. 2(b) is a diagram schematically showing an energization pattern in the method of joining dissimilar materials. As shown in FIG. 1(b), this dissimilar metal joining method uses a resistance welding apparatus 1 and rivets 30 to join a plurality of metal plates 40, 50, 60 including metal plates made of different metal materials. They are joined by resistance welding. In this embodiment, the aluminum plate 40 and the iron plates 50 and 60 are exemplified as the "plurality of metal plates", but the material of each metal plate is not limited to aluminum and iron.

The resistance welding device 1 includes an upper electrode 3 and a lower electrode 5, as shown in FIG. 2(a). The upper electrode (first electrode) 3 is formed in a cylindrical shape and configured as a flat electrode having a flat tip surface. The upper electrode 3 presses the rivet 30 downward against the laminated aluminum plate 40 and iron plates 50 and 60 . The lower electrode (second electrode) 5 is formed in a substantially columnar shape and configured as a radius electrode having a spherical tip surface. The lower electrode 5 is provided so as to face the upper electrode 3 with an aluminum plate 40 and iron plates 50 and 60 stacked vertically therebetween, and presses the aluminum plate 40 and the iron plates 50 and 60 upward. It's becoming

In this embodiment, as shown in FIG. 2A, the rivet 30 includes a substantially disk-shaped cap portion 31, a shaft portion 33 extending downward from the central portion of the cap portion 31, and a An iron one having an outer peripheral wall portion 35 extending in the same direction as the shaft portion 33 and forming a groove 37 between itself and the shaft portion 33 is used. The rivet 30 is set in the resistance welding device 1 so that the cap portion 31 is orthogonal to the stacking direction.

When joining the aluminum plate 40 and the iron plates 50 and 60, which are different metal materials, using the resistance welding device 1 and the rivet 30 configured as described above, the cap portion 31, the shaft portion 33, the aluminum plate 40 , iron plate 50 , iron plate 60 , rivet 30 , aluminum plate 40 , iron plate 50 and iron plate 60 are sandwiched between the upper electrode 3 and the lower electrode 5 in this order from top to bottom. , the aluminum plate 40, the iron plate 50 and the iron plate 60, while applying pressure with the upper electrode 3 and the lower electrode 5, a current is applied.

At this time, generally, as shown in FIG. 3( a ), a relatively high current is applied for a short time at the beginning of the energization to cause the shaft portion 33 of the rivet 30 to pass through the aluminum plate 40 . Then, after the middle period of energization, the shaft portion 33 of the rivet 30 penetrates the aluminum plate 40, and spot welding is performed between iron (the rivet 30 and the iron plates 50 and 60), so a relatively low current is applied. By applying the voltage for a long period of time, nuggets 70 as shown in FIG.

In this way, the shaft portion 33 of the iron rivet 30 and the iron plates 50 and 60 are welded together, and the aluminum plate 40 is sandwiched between the cap portion 31 of the rivet 30 and the iron plate 50, thereby making it possible to weld an aluminum plate that is difficult to weld. Joining 40 and iron plate 50 is a general dissimilar metal joining method.

However, in the present embodiment, as shown in FIGS. 1(a) and 2(a), the aluminum plate 40 already has a through hole 40a before resistance welding. Secondly, dissimilar materials are joined together using a technique different from the general method of joining dissimilar materials described above.

-Responding to conventional joint failures-
Here, in order to facilitate understanding of the present embodiment, a conventional countermeasure (repair) for joint failure will be described. FIG. 5 is a diagram schematically illustrating a conventional response to poor bonding. 5, the same resistance welding device 1 and rivet 30 as in the present embodiment are used.

As shown in FIG. 5( a ), a poor connection occurred between the rivet 30 ′ and the iron plate 50 (for example, the nugget 70 was formed between the iron plate 50 and the iron plate 60 , but the rivet 30 ′ and the nugget 70 was not joined), so that the aluminum plate 40 and the iron plate 50 are separated.

In this case, the old rivet 30' is removed and the new rivet 30 is used for the repair. As shown, a through hole 40 a having an inner diameter larger than the outer diameter of the shaft portion 33 of the new rivet 30 is formed in the aluminum plate 40 . Therefore, at the time of repair, a gap C is generated between the shaft portion 33 of the new rivet 30 inserted into the through hole 40a and the through hole 40a.

Then, as shown in FIG. 5(c), a current is applied while pressure is applied by the upper electrode 3 and the lower electrode 5. Since welding is performed, a relatively low current is applied over a relatively long period of time to weld the nugget 70 generated between the iron plates 50 and 60 and the shaft portion 33 . Since a relatively low current is applied in this way, the aluminum plate 40 is not affected by the energization, and a gap C remains between the shaft portion 33 of the rivet 30 and the through hole 40a. .

The repair is completed by re-welding the shaft portion 33 of the rivet 30 and the nugget 70 generated between the iron plates 50 and 60 as described above. As shown in FIG. 5(d), a gap C remains between the shaft portion 33 of the rivet 30 and the through hole 40a. For this reason, in the conventional countermeasure, since breakage occurs between the aluminum plate 40 and the rivet 30, there is a problem that the joint strength (shear strength) of the dissimilar metal joint member 110 is lowered.

Here, although it does not relate to re-welding, it is conceivable to employ a dissimilar metal joining method as shown in FIG. The conventional method for joining dissimilar materials shown in FIG. 6 is a method for unremovably fixing a component 140 having a hole 140a to a basic component 150 by means of a bolt 130, and the front end surface of the bolt 130 inserted into the hole 140a is used as a base. The bolt 130 is electrically welded to the surface of the component 150, and the shaft portion 133 of the heated and softened bolt 130 is crushed (plastically deformed so as to expand in the direction perpendicular to the axis) to fill the gap with the hole 140a. If this conventional method of joining dissimilar materials is applied to re-welding, the crushed shaft fills the gap C between the aluminum plate 40 and the rivet, so it seems possible to secure the strength.

However, in this conventional method for joining dissimilar materials, the plastic deformation of the shaft requires a separate reinforcing rivet to fill the gap between the aluminum plate 40 and the rivet, which increases the manufacturing cost. There is a problem.

－Dissimilar material joining method－
Therefore, in the method for joining dissimilar materials according to the present embodiment, the nugget 71 is generated and the gap between the rivet 30 and the through hole 40a is generated by applying a high current value for a short period of time without separately preparing a reinforcing rivet. I'm trying to fill the gap C.

Specifically, in the method of joining dissimilar materials of this embodiment, as shown in FIG. a step of sandwiching between the upper electrode 3 and the lower electrode 5 the new rivet 30 with the shaft portion 33 inserted into the through hole 40a and the laminated aluminum plate 40 and iron plates 50 and 60 so as to be arranged in order; and a pressurizing and energizing step of pressurizing and energizing the rivet 30 , the aluminum plate 40 and the iron plates 50 and 60 by the upper electrode 3 and the lower electrode 5 .

Then, in the pressurizing and energizing step, as shown in FIG. 1B, a nugget 71 is generated between the shaft portion 33 and the iron plate 50, and the vicinity of the through hole 40a in the aluminum plate 40 is melted. Thus, a relatively high current value is applied for a short time so that the gap C between the shaft portion 33 and the through hole 40 a is filled with the molten aluminum 41 .

Here, in order to generate the nugget 71 between the shaft portion 33 and the iron plate 50, when a relatively low current for generating the nugget 70 is applied as shown in FIG. As described above, since the aluminum plate 40 is not affected by the energization, the gap C remains between the shaft portion 33 of the rivet 30 and the through hole 40a.

Therefore, the “relatively high current value” in the present embodiment refers to a current value as high as the current value required to pass the shaft portion 33 through the aluminum plate 40 . As described above, in the method for joining dissimilar materials of the present embodiment, since the current value is approximately the same as the current value required to pass the shaft portion 33 through the aluminum plate 40, the aluminum plate 40 is melted, As shown in FIG. 1B, the gap C between the shaft portion 33 and the through hole 40a can be filled. As a result, as shown in FIG. 1C, the iron plate 50 with the nugget 70 already formed between it and the iron plate 60, the shaft portion 33 of the rivet 30 inserted into the through hole 40a of the aluminum plate 40, It is possible to manufacture the dissimilar metal joining member 10 in which the nugget 71 is generated between and the gap C between the shaft portion 33 and the through hole 40a is filled.

In addition, as shown in FIG. 3A, in the relatively long-time energization for generating the nugget 70, if a relatively high current value ( If a current value approximately equal to the current value is used, the "volume expansion of the molten aluminum 41" exceeds the "holding force of the cap portion 31 of the rivet 30". Moreover, the molten aluminum 41 may be discharged outside the cap portion 31 of the rivet 30 and become a burr.

In this regard, in the dissimilar metal joining method of the present embodiment, a relatively high current value is applied for a short period of time, and the aluminum base material is also removed to some extent when the old rivets 30' are removed. Therefore, even if a relatively high current is applied, the volume of expanding aluminum can be reduced. Therefore, since the "volumetric expansion of the molten aluminum 41" does not exceed the "pressing force of the cap portion 31 of the rivet 30", it is possible to suppress the occurrence of burrs.

-Test results-
Next, a test conducted to confirm the effect of the method for joining dissimilar materials according to this embodiment will be described. The test consisted of a dissimilar-materials-joined member with no joint failure, a dissimilar-materials-joined member 110 (conventional example) repaired by the conventional method shown in FIG. ) were processed into test pieces specified in JIS standard Z2201-5, and then subjected to a tensile test.

FIG. 4 is a graph diagram schematically showing the test results of shear strength. As shown in FIG. 4, in the conventional example in which the gap C between the shaft portion 33 and the through hole 40a remains, the tensile shear strength is reduced by about 25% compared to the dissimilar material joined member with no joint failure. On the other hand, in the example, it was confirmed that the same level of tensile shear strength as that of the dissimilar-materials-joined member with no joint failure could be ensured.

As described above, according to the method for joining dissimilar materials according to the present embodiment, it is possible to sufficiently ensure strength while suppressing an increase in manufacturing cost even when joining metal plates having through holes 40a. .

(Other embodiments)
This invention is not limited to embodiments and can be embodied in various other forms without departing from its spirit or essential characteristics.

In the above embodiment, three metal plates (aluminum plate 40 and iron plates 50 and 60) are joined, but the present invention is not limited to this, and for example, four or more metal plates may be joined.

In the above embodiment, the present invention is applied to repair defective joints, but the present invention is not limited to this, and may be applied to new joints of metal plates having through holes, for example.

Furthermore, in the above embodiment, the stacking direction and pressing direction of the metal plates are aligned with the vertical direction. However, the stacking direction and pressing direction are not limited to this. You may make it

Thus, the above-described embodiments are merely examples in all respects and should not be construed in a restrictive manner. Furthermore, all modifications and changes within the equivalent scope of claims are within the scope of the present invention.

According to the present invention, even when joining metal plates having through holes, it is possible to sufficiently ensure strength while suppressing an increase in manufacturing costs. It is extremely useful when applied to a method for joining dissimilar materials.

3 upper electrode (first electrode)
5 lower electrode (second electrode)
30 Rivet 31 Cap 33 Shaft 40 Aluminum plate (first metal plate)
40a through hole 50 iron plate (second metal plate)
71 nugget C gap

Claims (1)

A dissimilar material joining method for joining a plurality of metal plates including metal plates made of different metal materials by resistance welding using rivets,
a metal rivet comprising a cap and a shaft;
A first metal plate made of a metal material different from that of the rivet and having a through hole with a diameter larger than the outer diameter of the shaft of the rivet, and a second metal plate made of the same metal material as that of the rivet. a plurality of metal plates, including plates;
providing first and second electrodes;
The rivet having the shaft portion inserted into the through hole and the plurality of laminated metal plates are arranged in this order such that the cap portion, the first metal plate and the second metal plate are arranged in this order. sandwiching between the electrode of and the second electrode;
a pressurizing and energizing step of pressurizing and energizing the rivet and the plurality of metal plates by the first and second electrodes;
In the pressurizing and energizing step, a nugget is generated between the shaft portion and the second metal plate, and the gap between the shaft portion and the through hole is closed by melting the first metal plate. A method for joining dissimilar materials, wherein a current is supplied for a short period of time at a current value approximately equal to a current value necessary for passing the shaft portion through the first metal plate so as to be buried.

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