JPS60216983A - Seam welding method of metallic sheets having insulating surface films - Google Patents

Abstract

PURPOSE:To obtain a stable joint part of metallic sheets having insulating surface films without removing preliminarily the surface films from the parts to be joined by fitting a U-shaped metallic sheet to the edges mated face to face of said sheets and subjecting the edges to seam welding. CONSTITUTION:The end faces at edges on at least one side of the metallic sheets 1, 2 having the insulating surface films are superposed to face the same direction. The U-shaped metallic sheet (stainless steel sheet) 5 is fitted to the position to be welded of the superposed edges. Pressurizing force is exerted to both side faces of said sheet 5 by a pair of disk electrodes 6, 7 and a voltage is impressed to the electrodes, by which the metallic sheets are seam-welded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a seam welding method for metal plates having an insulating surface coating on one or both sides, and particularly relates to a method for seam welding metal plates having an insulating surface coating on one or both sides. This is related to seam welding methods. Traditionally, metal plate structures, containers, and the outer sheaths that surround them are generally manufactured by joining metal plates, and then depending on the material of the metal plates, corrosion resistance, appearance, etc. Painting is applied to the surface of the metal plate from the surface, but this type of painting generally has a short service life and has the disadvantage that it must be repainted every few years.

In order to improve the above-mentioned drawbacks, painted copper plates or laminated steel plates have recently been developed and put on the market.

Since the above-mentioned coated steel sheets are generally baked and painted, their service life is significantly longer than conventional ones coated at room temperature, and the above-mentioned laminated steel sheets are also becoming important because they can be used for a long period of time.

However, if painted or laminated steel sheets are to be used, for example, as structures, containers, or surrounding envelopes, the steel sheets must be joined and welded.

However, since the coating applied to the surface of the painted plow board or laminated steel plate is electrically insulating in nature, it is not possible to overlap the ends of the steel plates with these surface coatings and immediately weld them together. . Therefore, in order to weld and join steel plates that have such an insulating surface film, it is necessary to remove the surface film on the parts to be joined before welding, and removing such a film requires a lot of effort. It has the disadvantage that it takes a long time.

In order to eliminate the above-mentioned drawbacks, a coated steel sheet having a conductive film in which conductive metal powder is mixed into the insulating surface film is disclosed in Japanese Utility Model Application Publication No. 55-70234. However, such coated steel sheets are not only expensive, but also have the disadvantage that they tend to scatter during welding, and the electrodes are subject to considerable wear and tear.

JP-A-58-20384 discloses a method for eliminating and improving the various defects that occur when welding coated steel sheets having such insulating or conductive surface coatings in terms of the welding process. This method is a seam welding method for painted steel plates in which a substantially U-shaped shunt bar is fitted to the welding start edge of the painted steel plate, and the shunt bar is used as the welding start point.

In this method, the resistance heat generated when electricity is applied to the shunt bar by a pair of disk electrodes burns and carbonizes the coating film on the painted steel sheets, and the welding current is shunted between the polymerized painted steel sheets, which serves as the welding starting point. It is characterized by
The gist of this is that the applied welding current flows through the shunt bar, and the resulting heat destroys the paint film directly below, completely welding the part. This initial heat generation sequentially destroys the coating film along the weld line of the painted steel plate, so that subsequent seam welding can be completed and a good welding effect can be obtained as a whole. ”.

Generally, seam welding (2) involves overlapping a number of metal plates.

Pressure is applied with a pair of electrodes, and the welding current that flows in a certain part of both electrodes in a very short time causes resistance heat generation in the metal plate and gold 11.
Since it cleverly utilizes heat dissipation from the surface of the gold plate to the electrode, the temperature of the part of the gold bi plate in contact with the electrode is relatively low, and the temperature of the part of the gold bi plate in contact with the electrode is slightly off. The area to be welded in the direction in which the disk electrode moves forward is at a temperature close to room temperature. Therefore, the above-mentioned Japanese Patent Application Laid-Open No. 58-2
As in the method disclosed in No. 0384, when the electrode ring comes off the shunt bar and is on the insulating coating film of the painted steel plate, the coating film is sequentially destroyed along the weld line of the painted steel plate due to initial heat generation. However, it is difficult to maintain and continue welding.

Even if it were possible to weld by destroying the coating film due to heat conduction from the initial heat generation, it is inevitable that the speed at which the electrode wheel advances would be extremely slow, resulting in a significant drop in work efficiency.

Furthermore, according to this method, the welding conditions change at the end where the electrode ring comes off from the shunt bar, which not only destroys the thermal equilibrium balance and makes the welding unstable, but also causes the base metal The worst case scenario is that a hole is drilled in a coated steel plate, and it is difficult to use this method industrially due to the above two reasons.

The object of the present invention is to provide a seam welding method that can eliminate or improve the flaws observed in the seam welding method for metal plates having an insulating surface film, and the present invention is directed to a 1% allowance. The above objects can be achieved by providing a seam welding method as described herein. That is, the present invention overlaps the end surfaces of at least some of the edges of metal plates having insulating surface films so that they face the same direction, and performs so-called interlocking. A letter-shaped metal plate is fitted, and the U-? The present invention relates to a method of seam welding the out-of-plane surface of a :-shaped metal plate while holding it under pressure with a pair of disc electrodes.

The invention will now be explained in detail with reference to the drawings.

In Figure 1, the ends of the painted metal plates 1 and 2 are bent to form flanges 3 and 4, and after these flanges 3 and 4 are interlocked, a U-shaped shape is formed so as to cover the edges of the flanges 3 and 4. FIG. 7 is a perspective explanatory view showing one embodiment of the present invention in which a metal plate 5 is fitted and both sides of the U-shaped metal plate 5 are 7-m welded with a disk electrode 6.7.

Next, the present invention will be described in detail as follows.

When a pressure is applied to both sides of the U-shaped metal plate 5 by the disk electrode 6.7 and a voltage is applied between the two electrodes 6.7, a shunt current flows through the U-shaped metal plate 5, and the current The area directly below the dense electrode generates heat and reaches a high temperature, and the coating on the flanges 3 and 4 immediately below the disk electrode 6゜7 burns and carbonizes, causing the U-shaped metal plate 5 and flanges 3 and 4 to burn. A welding current flows between them to form a nugget and welding is performed. disk electrode 6,
The above-mentioned phenomenon is repeated as the rotational movement of 7 is repeated, and the seam welding progresses. 8 is a seam weld line welded in this manner.

The present invention will be described below with reference to Examples.

In conducting this experiment, the base material, U-shaped metal plate, shunt bar, welding conditions, etc. were as follows.

(1) Base material 8US 304 and 5US430: Surface coating Silicone modified acrylic resin coated twice, baked twice Coating thickness 20μ Reverse coating Acrylic resin baked Coating thickness 5μ 80G2
: JIS G3312 colored galvanized iron plate (2) U-shaped metal plate (total length 2m or more) 8PGR: JjS G3302 galvanized iron plate SUB 30
4 j JIS G4305 stainless steel plate (3)
Shunt bar SUS 304: Stainless steel plate Mild steel plate: Cu (4) Welding part 1 In the case of the embodiment according to the present invention, the length H of both sides of the U-shaped metal plate 5 is 2011111 as shown in FIG.
Then, a location H/2 from the tip of the curved portion of the U-shaped metal plate 5, that is, a location IOwta, was the welding location.

(5) Seam welding machine electrode: Internal water cooling Material: Chrome-steel Control method: Power synchronized type (single-phase AC) In the experiment of Comparative Example 7, the plate width W of the shunt bar IO was changed as shown in Fig. 4. A plurality of pieces were fitted onto the edge parts 3 and 4 of the painted metal plates 1 and 2 with a spacing S of 2Qma and a spacing S of 30 degrees.

Arranged and seam bathed. In addition, in the experiments of experiment numbers 8 and 9 of the comparative example, the width of one plate of the shunt bar was set to 20 mm, and this was used as the welding starting point.

As can be seen from the table, good seam welding could be performed in all of the experiments Nos. 1 to 6 of the examples according to the present invention. That is, when seam welding is performed by the method of the present invention using 5US304, 430 painted steel plates and 80G2 as base materials and BUS 304 and 8PGR, which have high electrical resistance values, as U-shaped metal plates, the formation of nuggets at the welding area is extremely good. Fully seam welded along the entire length of the edge of the painted metal plate. In particular, the best results were obtained when the U-shaped metal plate was a stainless steel plate such as 5US304.

On the other hand, according to Comparative Example Experiment No. 7, welding in the area with the shunt bar was good, but welding in the area without the shunt bar was not possible, and furthermore, at the boundary between the area with and without the shunt bar, welding was successful. The base material was burnt and holes were formed. The reason for the formation of holes in the base metal in this way is thought to be that the welding conditions change rapidly at the boundary, causing the base metal to melt.

Further, as a result of experiments using a copper plate as the shunt bar in Experiment Nos. 8 and 9 of the comparative example, it was not possible to seam weld the portion where the shunt bar was removed.

As is clear from the above results, according to the present invention, since seam welding is performed only on the U-shaped metal plate, there are the following various effects.

(1) Seam welding can be performed on painted metal plates at almost the same speed as unpainted metal plates.

(2) Heat is concentrated in the center of the overlapping part, resulting in a stable joint.

(3) There is almost no scattering.

(4) There is very little damage to the electrodes of the welding machine.

(5) It is safe because the U-shaped metal plate protects the cut portion of the joint.

(6) The U-shaped gold knitted plate and the painted metal plate have a W11 sum.
As a result, it has a beautiful appearance.

As described above, according to the present invention, when applying a polymerized coated copper plate or a laminated steel plate to a building, a container, an outer cover surrounding these, etc., it is very easy to apply it to any place that has a polymerized edge. It can be applied economically and has great practical effects.

[Brief explanation of drawings]

Fig. 1 is a perspective explanatory view showing one embodiment of the present invention, Fig. 2 is a perspective explanatory view of three insulating coated metal plates stacked together and fitted with a U-shaped metal plate, and Fig. 3 is a perspective explanatory view showing one embodiment of the present invention. An explanatory diagram showing the welding area, Figure 4 shows the shunt bar fitted to the edge of the painted metal plate,
It is a perspective explanatory view in the case of arrangement|positioning. 1, 2.9... Painted gold a plate, 3, 4... Flange,
・5... U-shaped metal plate, 6.7... Disc electrode, 8.
... Seam mm, 10... Shunt bar. Special d'1 Applicant Nippon Yakin Kogyo Co., Ltd. Agent Patent Attorney Mura 1) Political Patent Attorney Takuya Hatano Figure 1

Claims (1)

[Scope of Claims] l Metal plates having an insulating surface film are overlapped so that the end faces of at least some of the edges face in the same direction, and a U-shaped part is formed on the part of the overlapped edges to be welded. A metal plate having an insulating surface film, characterized in that a metal plate is fitted onto the U-shaped metal plate, and both outer surfaces of the U-shaped metal plate are pressed and clamped by a pair of disc electrodes, and then seam welded. seam welding method. 2. The seam welding method according to claim 7, wherein the U-shaped metal plate is a stainless steel plate.