JPH08309551A - Lap seam welding method for aluminum-based metal sheets - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a seam welding method for an aluminum-based metal sheet, which reduces welding current. [Structure] When seam welding is performed by continuously applying seam welding to a lap joint formed by stacking aluminum-based metal plates on each other through a seam welding electrode, applying a pressing force, a welding current, and a rotational driving force to the seam welding electrode. On the surface where the welding electrode contacts,
The seam welding is performed from above the thin plate with a thin plate made of a material having a higher melting point and a higher electric resistance than aluminum interposed. By doing so, Joule heat necessary for aluminum welding is generated and sufficient welding strength can be obtained even with a welding current value and pressure that are lower than when directly seam welding an aluminum-based metal sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lap seam welding method for aluminum-based metal sheets.

[0002]

2. Description of the Related Art Conventionally, lap seam welding of aluminum-based metal sheets requires a large current because aluminum has low electric resistance and high thermal conductivity, and there is an oxide film on the surface of aluminum. The heat generated between the electrode and the welding electrode increases the frequency of shaping the electrode surface, which promotes early wear of the electrode, which limits its use as seam welding of aluminum-based metallic materials.

Electric resistance welding of aluminum-based metal plates is
Spot welding, seam welding, flash welding, etc. have been put to practical use, and in the past, they were used only for special applications such as aircraft materials. Recently, it has been widely used in applications such as automobiles, vehicles, home appliances, and building materials. In resistance spot welding, the aluminum-based metal plate of the welded product is pretreated before welding, and the electrode surface is shaped and cleaned. Is performed frequently to enable welding. Seam welding requires a larger current than spot welding, and the use of aluminum seam welding is less popular than resistance spot welding.

[0003]

SUMMARY OF THE INVENTION The present invention focuses on the fact that conventional seam welding of aluminum-based metal plates requires a large current and a large pressing force, making it difficult to save the machine labor.
The aim is to expand the applications of aluminum seam welding by developing a seam welding method that reduces the welding current value required for welding aluminum-based metal materials and contributes to improved weldability.

[0004]

In order to achieve the above-mentioned object, the present invention takes the following technical means. The lap joint formed by stacking aluminum-based metal plates on top of each other is pressed through the electrode for seam welding.
When continuous seam welding is performed by applying a welding current and a rotational driving force, a thin plate made of a material having a higher melting point and higher electric resistance than aluminum is interposed on the side where the seam welding electrode is in contact, and The present invention provides a method for lap seam welding of an aluminum-based metal plate, which is characterized in that the seam welding is performed.

[0005]

In the above-mentioned structure, when aluminum seam plates are overlapped and seam welded, a thin plate of, for example, mild steel, stainless steel, brass, bronze, or titanium is attached to the surface of the welded joint where the seam welding electrode contacts. Since this thin plate has a higher melting point and higher electrical resistance than the aluminum base metal, sufficient Joule heat is generated with a smaller welding current value than when aluminum-based materials are directly seam welded. Furthermore, since mild steel, stainless steel, brass, bronze, and titanium have lower thermal conductivity than the aluminum base metal, the heat generated in the thin metal layer is efficiently transferred to the aluminum base metal without diffusion into the thin metal layer. As a result, the Joule heat necessary for aluminum welding can be generated even if the welding current value is small, and sufficient welding strength for aluminum welding can be secured. Moreover, the Joule heat generated between the thin plate layer and the aluminum layer is difficult to be transmitted to the electrode by these thin plate layers having a small thermal conductivity, and as a result, the temperature rise to the electrode is prevented. The number of dressings can be reduced and the electrode life can be extended. Further, since the interposed thin plate is in contact with the electrode having a large heat capacity, the temperature rise is small and the melting point is high, so that it is difficult to form an alloy with aluminum and no metallurgical problem occurs.
In addition, power saving and downsizing can be realized in the aluminum seam welding machine.

[0006]

FIG. 1 is a schematic view showing an embodiment of the method of the present invention. A thin plate is interposed on the surface of the aluminum-based metal plate of the workpiece to be contacted with the seam welding electrode. The surfaces where the aluminum base materials overlap each other have no inclusions, and the lap joint is formed so that the aluminum members contact each other. Then, this lap joint is pressed from above and below through the seam welding electrode to apply current to the thin plate material to drive the electrode wheel to form a continuous weld.

The following table shows experimental values of welding conditions when an experiment of the lap joint seam welding method of the present invention was conducted. [Experimental value] ○ Welding conditions Welding pressure KN Welding speed m / min Welding current value A Energization / Pause time cycle Welding evaluation 1. 1.0 1 6000 3/3 ◎ 2. 1.2 1 8000 3/3 x 3. 1.2 1 9000 3/3 ◎ 4. 1.2 1 10000 3/3 ◎

According to this experimental method, the lap joints of aluminum-based metal plates are sandwiched by seam welding electrodes from above and below for welding. In this case, for a thin plate made of a material having a higher melting point and a higher electric resistance than an aluminum-based metal plate, for example, titanium (Ti) having a thickness of about 0.3 mm is used, which is a pure wire having a thickness of 1.2 mm with which the seam welding electrode contacts. It is placed on the surface of an aluminum-based metal plate (Al). Then, the aluminum side was inlaid so that the aluminum base materials were in contact with each other, and the welded parts were pressed and energized with the seam welding electrode wheel over the titanium, and the electrode wheel was driven to rotate. Seam welding was performed.

Welding evaluation by this experiment was carried out according to the above items 1 and 3
As a result of performing a peel test on a work piece welded under the welding conditions described in Sections 4 and 4, a welding strength of 8.5 KN was obtained, and good welding results were obtained even with low welding current and pressure.

Compared with the case of directly welding aluminum to each other, under the conventional general seam welding conditions, a high welding current of 20,000 amperes or more is required, but when this is seam welded from above a titanium-based material, a welding current of 10,000 ampere or less is required. It was confirmed that even with this, sufficient Joule heat necessary for seam welding can be obtained.

The reason for this is that in seam welding of aluminum, a thin plate having a high melting point and a high electric resistance is placed on the side in contact with the electrode to prevent heat conduction escaping to the electrode and to be a high electric resistance material. This thin plate itself also generates heat, but this heat is transmitted to the electrode with a large heat capacity, and is transmitted to the aluminum side without being diffused into the titanium material with lower thermal conductivity, which contributes to the resistance weldability of aluminum. it is conceivable that.

As an embodiment of the method of the present invention, in addition to previously placing the thin titanium material on the upper and lower sides of the lap seam welded portion as described above, a butt portion formed by superposing two aluminum plates as shown in FIG. Seam welding under the same welding conditions as above is also a kind of the method of the present invention, while supplying a thin titanium material wound in a ribbon tape shape to the side where the seam welding electrode is in contact with from above and below.

[0012]

As described above, according to the aluminum resistance seam welding method of the present invention, when the aluminum-based metal plates are overlapped and seam-welded, the aluminum-based metal plates are overlaid with the same aluminum material. A lap joint is formed, and a thin plate with a high melting point and high electrical resistance is placed on the surface of the lap joint where the seam welding electrode wheel abuts, and pressure is applied from above the thin plate through the seam welding electrode wheel. Since a continuous welding part is formed by rotating this while applying a welding current, it is possible to perform seam welding of aluminum even with a relatively small pressure and a small current, and it is possible to downsize the welding machine and save labor. realizable.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a combination of dissimilar metal plates in a seam welded joint portion according to the method of the present invention.

FIG. 2 is a schematic diagram when the seam welding method of the present invention is used for lap butt welding.

Claims (1)

[Claims] 1. When continuous seam welding is performed by applying a pressure force, a welding current, and a rotational driving force to a lap joint portion formed by superposing aluminum-based metal plates on each other through an electrode for seam welding, An aluminum-based metal plate characterized in that a seam-welding material having a higher melting point and a higher electric resistance than the aluminum-based metal plate is interposed on the side where the seam-welding electrode is in contact, and the seam-welding is performed from above the thin-metal plate. Lap seam welding method.