JPH08155653A - Resistance welding method for aluminum materials - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a resistance welding method for an aluminum-based material, which can obtain high joint strength at a relatively low current when joining two or more materials to be welded made of aluminum or aluminum alloy by resistance welding. To do. [Structure] When joining materials to be welded made of aluminum or aluminum alloy by lap resistance welding, one or more patch plates made of aluminum or aluminum alloy are attached to both sides or one side of the welded joint to form a material to be welded. Aluminum or aluminum alloy,
Weld the backing plate at the same time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lap resistance welding method for aluminum-based materials made of aluminum or aluminum alloy.

[0002]

2. Description of the Related Art Lap resistance welding of an aluminum-based material made of aluminum or an aluminum alloy (hereinafter referred to simply as an aluminum-based material) is a pair of two or more plate-shaped materials to be welded made of an aluminum-based material. In this method, the material is held by electrodes, and the material to be welded is pressed by the electrodes to be energized to generate electric resistance and heat-weld the material to be welded made of an aluminum-based material. Lap resistance welding (hereinafter,
Resistance welding is generally widely used in various manufacturing industries.

However, aluminum-based materials are steel-based materials such as carbon steel or stainless steel (hereinafter referred to as steel-based materials).
In addition to having high electrical conductivity and high thermal conductivity, the resistance is small and it is difficult to generate heat and at the same time the heat easily escapes.Therefore, aluminum-based materials have been conventionally resistance welded by applying a large current for a short time. ing.

Therefore, a welding machine for steel having a small capacity cannot obtain a large current, and an existing welding machine for steel cannot be diverted for resistance welding of an aluminum material, and an expensive welding machine of a large capacity is used. Need to be introduced. In addition, the welder becomes large and it is not portable.

On the other hand, since the aluminum-based material has a high thermal conductivity, the temperature gradient in the plate thickness direction is small, and the cross-section penetration shape in the welded part shows a large penetration in the plate thickness direction, and the melted part (nugget) is welded. Spreads near the surface of the material. For this reason, when the tip of the electrode is worn away due to continuous spot welding, the molten area reaches the surface of the material to be welded, or the surface of the welded part becomes cracked, which greatly deteriorates the appearance of the welded part and at the same time results in electrode contamination. It also causes

Further, since an oxide film having high resistance exists on the surface of the aluminum-based material, the contact resistance between the material to be welded and the electrode is large, and the temperature gradient in the plate thickness direction is small. Becomes extremely high and easily press-bonds with the electrode made of copper alloy. Therefore, in the case of continuous spot welding of an aluminum material, it is necessary to frequently polish the electrode surface.

As described above, in the conventional resistance welding of the aluminum-based material, the problem of the welding machine due to the high required current, the melting region reaching the surface of the material to be welded, or the surface of the welded portion There are problems in welding quality such as cracking, and in that the service life of the continuous electrode is short and frequent polishing is required, resulting in a decrease in productivity.

Various measures have been taken to solve these problems and improve the resistance weldability of aluminum-based materials. First, there is a technique for reducing the welding current by increasing the resistance of the joint interface of the materials to be welded by interposing a substance having a higher resistance than the aluminum-based material of the materials to be welded. For example, JP-A-4-123879 and JP-A-4-123879
This technique is disclosed in Japanese Patent Application Laid-Open No. 5-69155 and Japanese Patent Application Laid-Open No. 6-12080.

However, it is very difficult to increase the resistance only at the joint interface, which is a problem of the technique for reducing the welding current by increasing the resistance at the joint interface between these materials to be welded. When increasing the resistance of the joint interface by surface treatment of the aluminum-based material to be welded, not only it is difficult to surface treat only one side, but also the surface-treated surface must be assembled so that it becomes the joint interface, There is a problem in the assembly process due to restrictions on the design.

Further, the method of inserting a high resistance substance at the joint interface cannot be interposed only in the welded portion (inside the nugget). For example, when Fe powder is used as the high resistance substance, Fe in the vicinity of the welded portion is used. There is a problem in that the powder always remains, and it comes into contact with the aluminum-based material of the material to be welded to cause electrolytic corrosion, so that anticorrosion treatment must be performed.

As a second technique for reducing the electric current in the resistance welding of the aluminum-based material, the current is reduced by interposing a metal having a higher specific resistance than the aluminum-based material between the material to be welded and the welding electrode. There is technology. For example, this technique is disclosed in Japanese Patent Application Laid-Open No. 57-56175 and Japanese Patent Application Laid-Open No. 6-71455.

However, a technique for reducing the current by interposing a metal having a higher specific resistance than the aluminum-based material between the material to be welded and the welding electrode is a surface side (electrode side) of the material to be welded. The heat generated in the above case becomes larger than that at the joint interface, and the surface of the welded portion of the material to be welded is melted. Therefore, when these intervening metals having a high specific resistance are removed after welding, there is a problem in the appearance of the welded portion. On the other hand, if these metals are not removed even after welding, using a dissimilar metal such as a steel-based material as a metal material having a higher specific resistance than an aluminum-based material causes corrosion problems similar to the above, so corrosion There are problems such as having to process.

Further, various developments have also been made on a technique for extending the life of electrodes in resistance welding of aluminum-based materials. For example, a method for reducing the contact resistance between the material to be welded and the electrode by surface treatment to prolong the life of the electrode in Japanese Patent Laid-Open No. 4-358094, and the material to be welded in Japanese Patent Laid-Open No. 4-322886. And the electrode are energized through a metal material so that the material to be welded does not come into direct contact with the electrode to prolong the life of the electrode, or to extend the life of the electrode in resistance spot welding of aluminum-based materials. For this purpose, various electrode materials and welding equipment have been developed.

There is also a weld bond method in which a joining method using an adhesive and a resistance spot welding method are used together. According to this weld bond method, since the bonded portion contributes to the joint strength, the joint strength per point becomes high, and the number of welding points to obtain the required joint strength is smaller than that of the resistance spot welding method only. It is said that productivity will improve as a result.

[0015]

However, for example, in the technique of reducing the contact resistance between the material to be welded and the electrode by surface treatment, it is difficult to surface-treat only one side as described above, and the surface-treated surface is Since the electrode must be assembled so that it is on the electrode side, there are restrictions on the design of the structure, and there are problems in the assembly process. Considering the cost, etc., it has not been put to practical use.

The present invention has various problems in the resistance welding of the above-mentioned aluminum-based material, that is, a problem due to a higher required current as compared with the resistance welding of the steel-based material, and deep penetration in the plate thickness direction. In order to solve the problems caused by the above and the problems caused by the short continuous spotting property, it is an object of the present invention to provide a resistance welding method for an aluminum-based material capable of obtaining high joint strength with a relatively low current.

[0017]

According to the present invention, when joining a material to be welded made of an aluminum-based material by lap resistance welding, one or more contact plates made of the aluminum-based material are provided on both sides or one side of the welded joint. In addition, it is a resistance welding method for an aluminum-based material in which a material to be welded and a backing plate are simultaneously welded. Further, the thickness of the patch plate is 1/10 or more and 4 mm or less of the thickness of the thinnest workpiece, and the size of the patch plate is 5 mm or more in the minimum length from the center. This is a resistance welding method for aluminum-based materials in which the material to be welded has a plate thickness of 0.4 mm or more and 2.0 mm or less and the same or different thickness.

[0018]

In the case of resistance-welding a material to be welded made of an aluminum-based material, as shown in FIG. 1, welding is performed without a conventional backing plate, and a tensile shear test is performed as shown in FIG. It deforms and breaks at the weld. This is because, since it is a lap joint, a step is generated in the direction in which the load is applied, and a moment is generated in the welded portion, which causes deformation. If the rigidity of the material to be welded increases, such as an increase in the plate thickness, the material will break even if the deformation is small.

Therefore, as shown in FIGS. 2 and 3, when a patch plate made of an aluminum-based material is attached to at least one side of the welded joint portion and the material to be welded and the patch plate are simultaneously welded, the rigidity of the patch plate is increased. As shown in FIG. 7, even if a high tensile shear load is applied, the welded joint portion is less likely to be deformed, and as a result, high joint strength can be obtained. Further, in some cases, a joint having a high strength that does not break only at the welded portion and also breaks the base metal as shown in FIG. 8 can be obtained.

On the other hand, when lap resistance welding is performed on a material to be welded made of an aluminum-based material, it is said that the thicker the thickness of the material to be welded, the larger the welding current required to obtain the required joint strength. By adding a backing plate, the interface between the material to be welded and the material to be welded increases, and as a result, the resistance between the electrodes increases, so a large amount of heat can be obtained with a relatively low current compared to conventional welding without a backing plate. It was found that welding is possible even with electric current.

Therefore, even if a patch plate is attached to one side of the welded joint, the effect of increasing the strength of the welded joint and reducing the welding current can be recognized, but if the patch plates are attached to both sides of the welded joint, the effect will be improved. It gets even bigger.

Further, the thicker the thickness of the patch plate is, the more the effect of increasing the strength of the welded joint can be expected, but the welding current becomes low when the thickness of the thickest welded material is more than double the thickness. Is no longer effective. On the contrary, if the thickness is thinner than 1/10 of the thickness of the thinnest material to be welded, the effect of increasing the strength of the welded joint is reduced. The most preferable thickness of the backing plate is equal to or more than the thickness of the thinnest material to be welded, and the thickness of the thickest material to be welded is 2
It is less than twice.

Further, according to the resistance welding method of the present invention, the joint efficiency per welding point is much higher than that in the conventional welding method without a contact plate. Therefore, the number of welding points for constructing a required welded structure is It requires less than the conventional method. In addition, the required joint strength can be obtained with a welding current lower than that of the conventional method, and because the thickness of the welded part increases due to the addition of a backing plate, the penetration does not deepen near the electrode-side surface of the workpiece. As compared with the conventional method, the temperature of the electrode-side surface of the material to be welded does not rise. As a result, it is not necessary to wear the welding electrode made of copper alloy, and the service life of the welding electrode is extended.

Regarding the size of the backing plate, when the backing plate becomes smaller, the heat capacity of the backing plate itself becomes smaller and resistance heat is easily generated, so that the effect of lowering the current can be expected, but the minimum length from the center of the backing plate is expected. If is less than 5 mm, the effect of increasing the strength of the welded joint is diminished. The larger the patch, the higher the joint strength, but the preferred minimum length of the patch is 10 mm.
That is all. Although the shape of the patch is not particularly limited,
Determine as necessary, such as polygonal or circular.

On the other hand, when the plate thickness of the material to be welded is increased, the rigidity of the material to be welded itself becomes high, so that the welded portion is less likely to be deformed even when a tensile shear load is applied, and the strength of the welded joint is increased by the method of the present invention. The effect cannot be expected so much. On the contrary, if the material to be welded has a small thickness, the required joint strength can be obtained even with a relatively low welding current. Even if the thickness of the material to be welded is too thin, the effect of the method of the present invention cannot be expected so much because it does not exist. Therefore, the thickness of the material to be welded may be 0.4 mm or more and 2.0 mm or less, and may be the same or different.

Even if the pad plate of the present invention can be a part of the structure, there is no problem. The effects of the present invention are not lost. Further, only the welded portion of the material to be welded can be folded back in double or triple to substitute for the backing plate in the present invention.

[0027]

EXAMPLES Examples of the present invention will be described below. Example 1 As a material to be welded, A5182 plate thickness 1.0 mm was applied in accordance with JIS Z 3136 spot welding joint tensile shearing method, 30 mm width × 100 m
A test piece cut to m length was prepared. On the other hand, as the backing plate, the same A5182 plate thickness 1.0 mm cut into 30 mm width x 30 mm length was used. As shown in Figs. 1 to 4, when the backing plate was not provided (comparative example), the backing plate was welded to the joint part. When attached to one side,
When one patch plate is attached to each side of the welded joint, and when two patch plates are attached to each side of the welded joint, lap resistance welding is performed and a tensile shear test is performed to determine the tensile shear load and welded part. The fracture diameters of were compared and examined. Table 1 shows the results.

The welding conditions are shown below. Welding machine: Single-phase AC resistance spot welding machine Electrode: R type electrode with 16mmφ and tip diameter of 100mm (Chromium copper alloy) Pressurizing force: 3000N One-step constant pressurization time: 140ms Welding current: 16kA, 24kA, 32kA

[0029]

[Table 1]

As shown in Table 1, the welding conditions are fixed,
When there is no patch plate (comparative example), when the patch plate is attached to one side of the weld joint, when one patch plate is attached to both sides of the weld joint, and when the patch plate is attached to both sides of the weld joint As a result of comparing the cases of adding one by one, compared with the case without a contact plate (comparative example), even if only one contact plate was attached to one side of the welded joint, the tensile shear load increased by 110% or more,
If one patch plate is attached to each side of the welded joint, 1
70% or more, and 190% or more when a patch plate was attached to each side of the welded joint.

Comparing the fracture diameters of the welded portions, the diameter of the fractured portion becomes larger when the patch plate is added even under the same welding conditions, and the fracture diameter becomes larger and the tensile shear load also increases as the number of patch plates increases. . In addition, when one or more patch plates were attached to both sides of the welded joint, welding at a current of 24 kA or more resulted in fracture of the welded material, resulting in fracture of the base metal and a very high tensile shear load of about 5000 N or more was obtained. . On the other hand, when welding at a low current of 16kA, the tensile shear load is only 1400N at most without the contact plate (comparative example), but even if only one contact plate is attached to one side of the welded joint,
It increased by 150% and increased by about 200% when one patch plate was attached to each side of the welded joint, and increased by about 300% when two patch plates were attached to each side of the welded joint. That is, even with a relatively low current of 16 kA, one patch plate was attached to one side of the weld joint to about 2000N, and one patch plate was attached to each side of the weld joint to produce 2700N,
By attaching two patches to each side of the weld joint
A high tensile shear load of 4000 N or more is obtained.

Example 2 In this example, as in Example 1, the material to be welded was A5182 plate thickness.
A test piece was prepared by cutting 1.0 mm into 30 mm width × 100 mm length in accordance with the tensile shearing method of JIS Z 3136 spot welded joint. On the other hand, the backing plate is 5000 series from 0.2 mm to 4.0 mm
Laminated resistance welding was performed using a 30 mm wide x 30 mm long piece of (Al-Mg series) aluminum material, and the relationship between the thickness of the backing plate and the tensile shear load was investigated. One patch plate was attached to each side of the welded joint, welding conditions were fixed as follows, welding was performed while changing the thickness of the patch plate, and a tensile shear test was performed. The results are shown in FIGS. 9 and 10.

The welding conditions are shown below. Welding machine: Single-phase AC resistance spot welding machine Electrode: R type electrode with 16mmφ and tip diameter of 100mm (Chromium-copper alloy) Pressurizing force: 3000N One step constant pressurization time: 140ms Welding current: 20kA, 24kA

As shown in FIG. 9, when the welding current is 20 kA, in the case of the comparative example without the patch plate, only a tensile shear load of at most 1800 N / point can be obtained, but even a thin plate of 0.2 mm can be used as the patch plate. A tensile shear load of 3000 N or more per point can be obtained by welding one piece on each side of the weld.
Since the rigidity of the welded joint increases as the thickness of the patch plate increases, the tensile shear load per point increases, and when the plate thickness of the patch plate is 1.2 mm or more, about 5000 N / point or more. A tensile shear load of was obtained. The thickness of the backing plate is 2 mm
The tensile shear load decreases as above, but this is because the thickness of the backing plate becomes too thick and the heat capacity of the joint increases, resulting in a nugget with the same size as when the backing plate thickness is 1.2 mm or 1.6 mm. This is because a larger heat input, that is, a welding current is required to obtain the above.

In the case of this example, the breaking diameter when the thickness of the backing plate was 2 mm was 5.55 mm on average for two pieces. On the contrary,
When the patch plate thickness is 1.2 mm, the breaking diameter is the average of 2 pieces.
If 6.40mm and the thickness of the caul plate is 1.6mm, the breaking diameter is 2
The average of the number was 6.24 mm. As described above, when the thickness of the pad plate becomes too thick, the nugget does not become large and the tensile shear load decreases. When the thickness of the backing plate is 1.2 mm and 1.6 m
Comparing the case of m, the breaking diameter at 1.2 mm is 6.40 m
The fracture diameter for m and 1.6 mm is 6.24 mm, and even though the fracture diameter is slightly smaller for 1.6 mm, higher strength is obtained than for 1.2 mm. It is thought that this is because the effect of the backing plate was exhibited because the rigidity of 1.6 mm was greater. Furthermore, when the thickness of the backing plate is increased, 1.2 mm
Although the tensile shear load is lower than in the case of 1.6 mm and 1.6 mm, the tensile shear load of 3000 N / point or more is obtained even with the 4.0 mm patch plate, and the strength is about twice as high as the comparative example without the patch plate. Has become.

On the other hand, when the welding current is increased to 24 kA, the tensile shear load is increased as a whole as shown in FIG. 10, and when the breaking mode is thin, the button breaks as shown in FIG. However, if the backing plate becomes thicker than 1.0 mm, the base metal will break as shown in Fig. 8 and extremely high joint strength can be obtained. Therefore, the same welding conditions can be applied to a 0.2 mm thin patch plate and a 4.0 mm thick patch plate (when 4.0 mm, the welding current is 20 kA).
In the case of welding with, the joint strength higher than that in the case without the contact plate of the comparative example is obtained. Especially when the material to be welded is 1.0 mm,
Welding with a contact plate of 1.0 mm to 2.0 mm (from the same thickness as the material to be welded and twice the thickness) results in extremely high joint strength, which results in fracture of the base metal.

However, in this embodiment, from 1.0 mm
The highest joint strength was obtained when the 2.0 mm patch was added, but this result suggests that the best thickness range will be different if the thickness of the material to be welded is different. The thickness of the material to be welded
When the thickness is 2.0 mm or less, even if a thin plate of 0.2 mm is added as a backing plate, one piece on each side of the welded joint, the diameter of the fusion zone (nugget) will be larger and the tensile shear load will be higher than the comparative example without the backing plate. . On the contrary, if a thin aluminum plate of 0.4 mm is used as the material to be welded and a thick patch plate of 2.0 mm is attached under the same welding conditions (welding current: 20 kA), it will be about 3 times that of the comparative example without the patch plate. A tensile shear load of is obtained.

Therefore, in the present invention, the thickness of the patch plate is limited to 1/10 or more of the thickness of the material to be welded, and the thickness of the patch plate is too thick if it is too thick (appearance). The effect was confirmed in this example from the problem of increasing the weight of the welded structure due to the addition of a contact plate and a contact plate, and the effect was confirmed in this example to be 4 mm or less.
The thickness range of double or more and 2 mm or less is limited as the best thickness range of the patch plate.

Example 3 As in Example 1, the material to be welded was A5182 plate thickness 1.0 mm JIS Z
In accordance with the 3136 spot welded joint tensile shear method,
A test piece cut into 30 mm width × 100 mm length was prepared. On the other hand, as the backing plate, as in Example 1, A5182 plate thickness of 1.0 mm was used, and a square having a side length of 10 mm to 50 mm and a width of 30 mm.
Prepare a rectangular backing plate with a length of 10 mm to 100 mm and attach it to both sides of the weld joint as shown in Figs. 11 and 12.
The influence of the size of the patch plate (length of one side) and the length of the patch plate on the welded joint strength was investigated by carrying out lap resistance welding with each piece attached and performing a tensile shear test. Fig. 13 and Fig. 14 show the results of investigations with the welding conditions fixed as shown below and the size (length of one side) of the caul plate and the length of the caul plate changed.

The welding conditions are shown below. Welding machine: Single-phase AC resistance spot welding machine Electrode: R type electrode with 16mmφ and tip diameter of 100mm (Chromium copper alloy) Pressurizing force: 3000N One-step constant pressurizing time: 140ms Welding current: 20kA

As shown in FIG. 13, even if a small square aluminum plate having a side length of 10 mm is used as a backing plate, a tensile shear load about twice that of the comparative example without the backing plate can be obtained. It was The joint strength increases as the length of one side of the caul plate increases and the size of the caul plate increases, but even if the caul plate exceeds 30 mm, the joint strength does not increase so much. On the other hand, regarding the influence of the length of the backing plate, if the length of the backing plate is 10 mm or more as shown in FIG. 14, a tensile shear load about twice that of the comparative example without the backing plate is obtained. The effect of adding a backing plate is recognized.

In this example, a patch plate made of a square or a rectangle having a side length of 10 mm or more was investigated, but the effect of the present invention is not lost even if the patch plate is not a square or a rectangle. For example, as shown in FIG. 15, a polygonal shape, a circular shape, an elliptical shape, or the like may be superior in terms of aesthetics of the welded portion depending on the welded structure.

Example 4 In this example, the patch plate was fixed to A5182 1.2 mm plate thickness × 30 mm width × 30 mm length, and the plate thickness of the material to be welded was changed to obtain the effect of the method of the present invention on the plate thickness of the material to be welded. investigated. A5 as the material to be welded
182 Plate thickness 0.4mm, 0.8mm, 1.0mm, 1.2mm, 2.0mm 5
Similar to Example 1, aluminum materials having different plate thicknesses are used.
A test piece was prepared by cutting it into a width of 30 mm and a length of 100 mm. Welding conditions were fixed as follows, and lap resistance welding was performed for the case without a backing plate (comparative example) and the case where one backing plate was attached to both sides of the weld joint, and a tensile shear test was performed. The tensile shear load and the fracture diameter of the weld were compared and examined. The results are shown in Table 2.

The welding conditions are shown below. Welding machine: Single-phase AC resistance spot welding machine Electrode: R type electrode with 16mmφ and tip diameter of 100mm (Chromium copper alloy) Pressurizing force: 3000N One-step constant pressurizing time: 140ms Welding current: 20kA

As shown in Table 2, the welding conditions were fixed,
Comparing the case without a backing plate (comparative example) and the case where one backing plate is attached to both sides of the welded joint, when the thickness of the material to be welded is 0.4 mm, a backing plate of 1.2 mm is welded to the joint. Even if the welding conditions are the same, by adding one sheet on each side of the part, the tensile shear load is increased by 200% or more compared to the case without the contact plate (Comparative Example). This increase rate increases as the plate thickness of the material to be welded increases to 0.8 mm, 1.0 mm, and 1.2 mm, and increases to over 300% for 1.0 mm and 1.2 mm. When the plate thickness of the material to be welded is as thick as 2.0 mm, the rigidity of the material to be welded becomes high, so the rate of increase in tensile shear load is low, but it is 150% compared to the case without a patch (comparative example).
The tensile shear load is increasing.

[0046]

[Table 2]

Example 5 In this example, it is assumed that the present invention is applied to the joining of aluminum plates in an actual structure instead of a test piece, and A518 is used.
2 When two aluminum plates cut from a plate thickness of 1.0 mm to a width of 400 mm and a length of 100 mm were subjected to lap resistance welding, the case of applying the present invention was compared with a comparative example without a patch plate.

The welding method is A5182 1.0 mm plate thickness x 400 mm width x
As shown in Fig. 16, a plate with a length of 100 mm is piled up by 30 mm, and a plate of 35 mm
We welded 11 spots on the pitch. Further, in the present invention example, as the patch plate, a patch plate of A5182 1.0 mm plate thickness × 30 mm width × 400 mm length was attached to each side of the weld joint part as shown in Fig. 17, and a case of A5182 1.0 mm plate. Figure of a patch plate of thickness × 30 mm width × 30 mm length
There are two types when 18 pieces are attached to both sides of the welded joint as shown in 18. The welding conditions were fixed as follows.

The welding conditions are shown below. Welding machine: Single-phase AC resistance spot welding machine Electrode: R type electrode with 16mmφ and 100mm tip diameter (chromium copper alloy) Pressurizing force: 3000N One-step constant pressurizing time: 140ms Welding current: 24kA

After welding, a test piece having a width of 30 mm was cut out at each welding point and subjected to a tensile shear test. Figure 19 shows the result.
Shown in Although the welding conditions are the same, the tensile shear load is 2000 N to 3000 N per point in the case of the comparative example without the patch plate, whereas in the case of the present invention, it is approximately 5000 N.
A tensile shear load about twice that of the comparative example was obtained with N.

Although the embodiment of the method of the present invention has been described above, the effect of the present invention is not lost even if the welding machine, welding conditions, electrode shape, etc. are changed. Further, although the effect of the method of the present invention has been evaluated by the tensile shear load per welding point, it is easy to obtain high strength at a relatively low current by the method of the present invention in the cross tension test as well from the examples. Can be estimated. Further, according to the method of the present invention, since the welded portion is reinforced by the contact plate, it is apparent that the fatigue strength and impact performance of the welded joint are significantly improved as compared with the comparative example without the contact plate. Further, even if the surface condition of the material to be welded is poor such as oil adherence and the weldability (continuous spotting property) is inferior, if only the surface condition of the patch plate material of the method of the present invention is good, the welding electrode It can be easily estimated that welding can be performed without being contaminated.

[0052]

As is apparent from the above description,
According to the present invention, a very high joint strength can be obtained with a relatively low welding current as compared with the conventional resistance welding method, and even a welding machine with a small capacity can perform welding, and the number of welding points for obtaining the required joint strength can be obtained. It is effective in improving the productivity of the welded structure because there is less.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a conventional resistance welding method.

FIG. 2 is a diagram illustrating a resistance welding method of the present invention.

FIG. 3 is a diagram illustrating a resistance welding method of the present invention.

FIG. 4 is a diagram illustrating a resistance welding method of the present invention.

FIG. 5 is a diagram illustrating a tensile shear test of a joint by a conventional resistance welding method.

FIG. 6 is a diagram illustrating a fracture mode of a joint by a conventional resistance welding method after a tensile shear test.

FIG. 7 is a diagram illustrating a tensile shear test of a joint by the resistance welding method of the present invention.

FIG. 8 is a diagram illustrating a fracture mode after a tensile shear test of a joint by the resistance welding method of the present invention.

FIG. 9 is a diagram showing the relationship between the thickness of the backing plate and the tensile shear load when the welding current is 20 kA.

FIG. 10 is a diagram showing a relationship between a thickness of a patch plate and a tensile shear load when a welding current is 24 kA.

FIG. 11 is a schematic view showing the shape of a test piece of Example 3.

FIG. 12 is a schematic view showing the shape of a test piece of Example 3.

FIG. 13 is a diagram showing the relationship between the length of one side of a backing plate and the tensile shear load.

FIG. 14 is a diagram showing a relationship between a length of a patch plate and a tensile shear load.

FIG. 15 is a schematic diagram showing the shape and size of a backing plate.

16 is a schematic diagram showing the shape of a test piece of Example 5. FIG.

FIG. 17 is a schematic diagram showing the shape of a test piece of Example 5.

FIG. 18 is a schematic view showing the shape of a test piece of Example 5.

19 is a diagram showing test results of Example 5. FIG.

[Explanation of symbols]

1 ... material to be welded, 2 ... electrode, 3 ... patch plate, M ... minimum length from center of patch plate.

Claims (6)

[Claims] 1. When welding a material to be welded made of aluminum or an aluminum alloy by lap resistance welding, one or more caul plates made of aluminum or an aluminum alloy are attached to both sides of the welded joint to form the material to be welded. A resistance welding method for an aluminum-based material, which comprises simultaneously welding aluminum or an aluminum alloy and the patch plate. 2. When joining materials to be welded made of aluminum or aluminum alloy by lap resistance welding, at least one patch plate made of aluminum or aluminum alloy is attached to only one side of the welded joint portion to form a material to be welded. A resistance welding method for an aluminum-based material, which comprises simultaneously welding a certain aluminum or aluminum alloy and the contact plate. 3. The aluminum-based material according to claim 1 or 2, wherein the thickness of the patch plate is 1/10 or more of the thickness of the thinnest material to be welded and 4 mm or less. Resistance welding method. 4. The resistance welding method for an aluminum-based material according to claim 1, wherein the thickness of the patch plate is not less than the thickness of the thinnest material to be welded and not more than 2 mm. 5. The aluminum according to claim 1, 2 or 3 or 4, wherein the shape of the backing plate is a polygon, a circle or an ellipse whose minimum length from the center is 5 mm or more. Resistance welding method for base materials. 6. The material to be welded has a thickness of 0.4 mm or more, 2.
The resistance welding method for an aluminum-based material according to claim 1, 2 or 3 or 4 or 5, wherein the thickness is 0 mm or less and the thickness is the same or different.