JP3067519B2 - Resistance seam welding method for resin coated steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for resistance seam welding of a resin-coated steel sheet obtained by applying an organic resin to the surface of a galvanized steel sheet or a zinc-based alloy-coated steel sheet.

[0002]

2. Description of the Related Art A resin-coated steel sheet obtained by applying an organic resin to the surface of a galvanized steel sheet or a zinc-based alloy-coated steel sheet has been widely used in the industrial fields such as automobiles and electric machines due to its good corrosion resistance. However, when performing resistance welding on resin-coated steel sheets in the assembly process, etc., the organic resin, which is an electrical insulating material, inhibits the electrical conductivity, and tends to cause insufficient welding strength, poor weld bead shape, surface melting of the steel sheet, etc. Become
This makes it difficult to perform stable resistance welding work.

To prevent such a decrease in the resistance weldability of the resin-coated steel sheet, a method of spot welding in which spot welding is performed is disclosed in Japanese Patent Laid-Open No. 1-29079.
No. 8 discloses a technique for improving resistance weldability by limiting the components of an organic resin. Japanese Patent Application Laid-Open No. 2-145774 discloses a method for improving the resistance weldability by increasing the surface roughness of a steel sheet to make the thickness of the resin film non-uniform, and setting the thin portion of the resin film as a current-carrying point. Techniques are disclosed.

[0004] However, in the improvement of the material as described above,
The original function of corrosion resistance may be reduced, and the effect of improving the resistance weldability is limited due to the non-conductivity of the organic resin. Furthermore, even in the case of resistance spot welding, the same welding principle is used, but in resistance seam welding, in which welding is performed continuously while rotating a disk-shaped welding electrode to obtain tightness, the occurrence of poor welding is airtight. It becomes defective and becomes a big problem. Therefore, it is absolutely necessary to establish welding conditions for performing a stable welding operation, but such a resistance seam welding method has not been found yet.

[0005]

As described above, in the resistance seam welding of resin-coated steel sheets, an effective welding method capable of improving the weldability has not been established. Accordingly, an object of the present invention is to provide a resistance seam welding method for a resin-coated steel sheet that can improve resistance seam weldability and achieve good weld joint quality by performing a stable welding operation.

[0006]

The resistance seam welding method for a resin-coated steel sheet according to the present invention comprises applying an organic resin to a surface of a galvanized steel sheet or a zinc-based alloy-coated steel sheet in a thickness of 0.1 to 2.0 μm. when performing the resistance seam welding of the resin-coated steel plate obtained by, tree configuration to weld interface to the electrode pressurizing force applied from the welding electrode to be welded material satisfying the equation relationship of the following
A resistance seam welding method for a resin-coated steel sheet, wherein a stable energization path is secured by breaking and pulverizing a grease film . That is, P ≧ 50 · W · t ² where, P: electrode pressing force (kgf) W: welding electrode width (mm) t: thickness of resin-coated steel sheet (mm)

[0007]

According to the method for resistance seam welding of a resin-coated steel sheet according to the present invention, the electrode pressure is appropriately set.
The resin film at the welding interface is broken and crushed so that a stable current path can be secured. The electrode pressure is measured per unit width of the welding electrode, and in consideration of the fact that the greater the thickness of the resin-coated steel plate, the greater the bending stiffness and the less the concentration of the pressure on the welding interface, the necessary electrode pressure is considered. Pressure P
Is given by an equation proportional to the square of the sheet thickness t, which is related to the welding electrode width W and the section modulus of the resin-coated steel sheet.

[0008] The welding conditions such as welding current, welding speed and the like are reduced by the destruction and pulverization of the resin film at the welding interface. The same condition range as that described above can be set, and by performing a stable resistance seam welding operation, good welded joint quality can be obtained.

The contact length between the welding electrode and the material to be welded varies depending on the diameter of the welding electrode, and the surface pressure received by the material to be welded from the welding electrode varies. However, the contact length is approximately 1 / the diameter of the welding electrode.
Since it is proportional to the square, the effect is small if the outer diameter is in the range of about 100 to 400 mm, which is considered to be generally used industrially. Also, the distribution of surface pressure applied to the material to be welded varies depending on the curvature of the welding electrode tip, but when the curvature is large, the actual pressure receiving surface becomes narrower but the surface pressure increases, so that the same as when the welding electrode tip is flat The effect of is shown. Therefore, it is sufficient to consider the apparent average surface pressure, and the shape of the welding electrode need not be particularly limited.

The thickness of the resin film is intended to be 0.1 to 2.0 μm which is usually used, and the thickness of the resin film exceeding 2.0 μm is required to obtain higher corrosion resistance. About those which gave, destroying the resin film of the weld interface by the pressure of the welding electrodes, it becomes difficult to ensure a stable current path to ground and out of the scope of the present invention.

[0011]

EXAMPLES The effects of the present invention will be described below with reference to specific examples. As shown in FIG. 1, one surface galvanized or zinc - resistance seam resin-coated steel plate 1 where the organic resin is applied on the nickel alloy plating, a surface coated with an organic resin in the weld interface side in various welding conditions Welding was performed, and when the appropriate welding current width was 2 kA or more, the weldability was determined to be good (○), and when less than 2 kA, the weldability was determined to be poor (x). Here, the appropriate welding current width is defined as the minimum welding current (lower limit appropriate welding current) required to obtain welding strength that does not break at the welding interface, resulting in an unstable weld bead shape or a surface melting of the steel sheet. This is the range of the welding current up to the welding current (upper limit appropriate welding current) that is limited so as not to cause the welding, and it is necessary that the appropriate welding current width is 2 kA or more for stable resistance seam welding work.

The plating amount of the resin-coated steel sheet 1 was set to 20 g / m ² in a usual range. The welding electrode 2 was made of chromium copper and had an outer diameter of 150 to 250 mm, and the welding speed was set to a condition used in normal resistance seam welding in which continuous energization was performed at 2.5 to 3.5 m / min. Table 1 shows the results.

[0013]

[Table 1]

As can be seen from Table 1, the electrode pressure P is
If the relationship of P ≧ 50 · W · t ² is satisfied with respect to the electrode width W and the steel plate thickness t, the appropriate welding current width is 2 kA or more, and a stable resistance seam welding operation can be performed.

In the above-described embodiment, the case where the resin coating is provided only on the welding interface side is shown. However, even when the resin coating is provided on both surfaces, the resistance seam welding method for the resin-coated steel sheet according to the present invention can be applied. In other words, if an electrode pressure sufficient to destroy the resin film at the welding interface is applied, the resin film on the welding electrode side to which the electrode pressure is directly applied is naturally destroyed,
This is because a stable energizing path can be ensured even when there is a resin film on both surfaces.

In the resistance seam welding method for a resin-coated steel sheet according to the present invention, the upper limit of the electrode pressing force P to be applied is not specified, but an excessive electrode welding force is considered in consideration of the durability of the resistance seam welding machine. It goes without saying that the pressure P should not be used.

[0017]

As described above, according to the present invention, the resistance seam weldability can be improved by applying an appropriate electrode pressing force when performing resistance seam welding of a resin-coated steel sheet. Joint quality can be stably ensured.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a state of resistance seam welding of a resin-coated steel sheet.

[Explanation of symbols]

 1 Resin coated steel plate 2 Welding electrode

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B23K 11/00 B23K 11/36 330

Claims (1)

(57) [Claims] An electrode pressing force is applied when performing resistance seam welding of a resin-coated steel sheet obtained by applying an organic resin to a surface of a galvanized steel sheet or a zinc-based alloy-coated steel sheet in a thickness of 0.1 to 2.0 μm. the set so as to satisfy the equation of relation of the following welding
A resistance seam welding method for a resin-coated steel sheet, wherein a stable energization path is secured by breaking and pulverizing a resin film at an interface . P ≧ 50 · W · t ² where, P: electrode pressure (kgf) W: welding electrode width (mm) t: thickness of resin-coated steel sheet (mm)