JPH0224191B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for welding the edges of hot-dip galvanized steel strips.

In conventional continuous coating equipment for galvanized steel sheets, for example, two steel sheet coils are arranged in parallel, and when one coil finishes unwinding the steel sheet, the other coil starts unwinding, and even after one coil finishes unwinding the steel sheet. Painting was performed continuously without stopping the equipment. When the end of the steel plate of one coil and the tip of the steel plate of the other coil are overlapped and welded, the disc-shaped electrode is rolled along the welding line,
Continuous welding was performed by passing welding current continuously.

However, in such continuous welding, the welding line is continuous, so the welding current is not concentrated at the welded part, but is branched to the already welded part. In addition, especially with thin plates, the welding surface and the electrode contact surface are close, so if the welding current is even slightly less than the appropriate amount, the welding surface will not melt and the welding will be defective.On the other hand, if the welding current is even slightly higher than the appropriate amount, the plate will melt to the electrode contact surface and the electrode will contact the electrode. The weld will adhere to the weld, causing breakage and holes in the weld. For this reason, the range of appropriate conditions is narrow, and even a slight change in conditions results in poor welding.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for solving the above-mentioned drawbacks and minimizing defects in welds.

In order to achieve this object, the configuration of the present invention is such that when strip steel strips are alternately paid out from two parallel molten-plated steel coils, and the steel plate feeding end of one coil is overlapped with the steel plate feeding start end of the other coil and welded, In the steel strip having a thickness t of 0.2 to 0.6 mm, welding is performed intermittently in the width direction within a range of a welded portion length H = 10 to 50 mm and a non-welded portion length C = 3 to 10 mm.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Steel strips W are alternately fed out from two parallel galvanized steel coils 1 and 2, and the steel plate feeding end of one coil is overlapped with the steel plate feeding start end of the other coil and welded by disk-shaped electrodes 3, 3. Note that 4 is a direction change roll, 5 is a pretreatment device, and 6 is a coating device.

Now, when welding, the electrodes 3, 3
Intermittent welding is performed by periodically energizing the welded part length H and the non-welded part length C. In the case of plate thickness t (mm) = 0.27 and overlap margin S (mm) = 2.0, good results were obtained with H = 25 mm and C = 5 mm.

Note that H=10 to 50 mm is desirable; if it is less than 10, the welding strength will be insufficient, and if it exceeds 50, the effect of intermittent welding will be lost due to shunt. Further, it is desirable that C=3 to 10 mm; if it is less than 3, welding may be continuous, and if it is more than 10, the welding strength will be insufficient.

The present invention is also applicable to aluminium-plated steel sheets and zinc-aluminum alloy-plated steel sheets.

As described above, in the present invention, since intermittent welding is performed, the welding current is effectively concentrated in the welded part, and a good welding result can be obtained. In particular, it has a remarkable effect on thin plated steel sheets of 0.2 mm to 0.6 mm.

[Brief explanation of drawings]

Figure 1 is an overall system diagram showing the implementation status of this method;
FIG. 2 is an enlarged view of the main part, and FIG. 3 is a sectional view thereof. W... Galvanized steel plate, 1, 2... Coil, 3
……electrode.

Claims (1)

[Claims] 1. When steel strips are alternately fed out from two parallel molten-plated steel coils, and the steel plate feeding end of one coil is overlapped with the steel plate feeding start end of the other coil and welded, the thickness of the steel band is t = 0.2 to 0.6 mm.
The weld length in the width direction H = 10 to 50
A method for welding edges of hot-dip galvanized steel strips, characterized by welding intermittently in the range of 3 mm to 10 mm, and the length of the non-welded portion C = 3 to 10 mm.