JPS62185864A - Hot dipping method - Google Patents

Abstract

PURPOSE:To inhibit the sticking of dross to a steel strip to be hot dipped and to enhance the quality and yield of a hot dipped steel strip by placing a small tank at the upper part of a molten metallic bath in a hot dipping tank, immersing the lower part of a guide roll in a molten metallic bath in the small tank and introducing the steel strip to be hot dipped into the small tank to carry out hot dipping. CONSTITUTION:A small tank 4 is placed at the upper part of a molten metallic bath 3 in a hot dipping tank 2. A guide roll 6 is put in the tank 4 so that a part of the roll 6 under the axial core 7 is immersed in a molten metallic bath 5 in the tank 4. A steel strip 8 to be hot dipped is introduced into the tank 4, where it is hot dipped. At this time, the steel strip 8 is positioned in the bath 5 before it is brought into contact with the roll 6. The molten metal 3 in the tank 2 is supplied to the small tank 4 during hot dipping.

Description

[Detailed description of the invention] (Industrial application field) ~ The present invention relates to a molten metal plating method.

(Prior art and its problems) As a method for plating molten metal, for example, plating zinc, aluminum, etc., as described in Japanese Patent Publication No. 48586/1986 and Japanese Patent Application Laid-open No. 177169/1982, a guide roll in a bath is used. By guiding the plated steel strip by positioning it directly on the surface, the guide rolls prevent the dross accumulated at the bottom of the bath from spreading into the bath, and also reduce the accumulation of dross, which prevents the coating steel from adhering to dross. Although there are methods to prevent deterioration of the surface cleanliness of the strip, even with such techniques, it is difficult to reliably prevent surface deterioration due to dross, and satisfactory results cannot be obtained.

The present invention has been made to advantageously solve these difficulties.

(1!!!!! [Means for solving the problem) The present invention provides a method in which a small bathtub is arranged in the upper part of the bath of the molten metal plating bathtub, and the upper part of the roll is positioned in the bath of the small bathtub. The plated steel strip is guided and plated so that it is located in the bath of the small bathtub at the point where the plated steel strip contacts the guide roll, and the molten plated metal in the molten metal plating bath is plated. This is a molten metal plating method characterized by replenishing a small bathtub.

(effect) The operation of the present invention will be explained with reference to the drawings.

As shown in the PtIJ1 diagram, the end 1 of the pretreatment furnace is located in the bath 5 of the small bath 4 placed above the bath 3 of the molten metal plating bath 2, and a guide roll is placed on the outlet side of this end 1. Place 6.

The guide roll 6 is positioned below the axis 7 of the roll into the bath 5, and the steel strip 8 is positioned W1 into the bath 5 as shown in the figure before contacting the guide roll 6 via the deflector roll 9.
(pass through) and lead (possibly plated on both sides, bath 5
The amount of plating deposited is controlled by gas injection from the gas injection nozzle 10.

On the other hand, the plating metal is replenished into the small bathtub 4 by an electromagnetic pump 11 (or an in-vehicle type metal pump, etc.).
A bath 3 in the molten metal plating bath 2 is introduced through the bath 2, and a plating mass corresponding to the amount of plating consumed is introduced into the bath 3,
Adjust to the specified bath composition and bath temperature.

However, by providing the small bathtub 4 as described above,
Since the residence time of the bath 5 is shortened, the growth of dross is almost eliminated, so even if dross adheres to the surface of the plated steel strip, it does not become a defect that impairs the quality. That is, if there is no small bathtub 4, substances that cause dross such as intermetallic compounds and oxides will enter the bath from the steel strip 8, plating equipment, etc.
This floats and settles as fine dross and grows over time, becoming enlarged and gigantic dross. If this adheres to the plated steel strip, it will cause quality problems, but if the small bath 4 is installed, the amount of the bath 5 is small, so the residence time of the plating bath will be reduced due to plating consumption, and the agitation of the dross, Dispersion is promoted and the amount of deposits in the bath is reduced. Further, the generation of fine dross is suppressed, and at the same time, the growth of enlarged dross does not adhere to the plated steel strip and be carried out, thereby impairing quality.

Further, the small bath Wg4 can be arranged separately from the molten metal plating bathtub 2, and it is also effective to provide a heating medium in the guide roll 6 and the deflector roll 9 and heat it as necessary. .

(Example) Next, examples of the method of the present invention will be listed together with comparative examples.

■ Idroll (roll material: tungsten surface sprayed roll) diameter: 800 m5 ■ Position of guide roll in bath: 200-1 immersion ■ Metsuto bath: Zinc bath (480℃) ■ Line speed: 100 m/min ■Small bathtub volume 0.7 cm In this way, steel strip width 1450s, thickness 0,8
When 10,000 pieces were continuously plated at a plating thickness of 45 g/2 mm, no dross was observed to accumulate in the small bath, and of course there were no quality defects in the plated steel strip due to dross.

14+a' without arranging a small bathtub as in the present invention
When the plating bath was carried out under the same conditions as in the example, 8
After 1,000 tons of plating, dross adhesion, which was a quality problem, was observed, so the stripping process was stopped and the dross was removed.

(Effects of the invention) By doing this, the adhesion of dross that is detrimental to the quality of the plated steel strip is eliminated, the quality and yield can be improved, and IL during thrusting due to dross adhesion can be avoided. , excellent effects such as improved line operation rate and increased productivity can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the present invention. DESCRIPTION OF SYMBOLS 1... End of pretreatment furnace, 2... Molten metal plating bathtub, 3... Bath, 4... Small bathtub, 5... Bath, 6...
Guide roll, 7... Axis core, 8... Steel strip, 9...
Deflector roll, 10... Gas injection nozzle, 11
...Electromagnetic pump, 12...Piping.

Claims (1)

[Claims] (1) A small bathtub is placed in the upper part of the bath of the molten metal plating bathtub, a guide roll is placed in the bath of the small bathtub and the part below the axis of the roll is placed, and the plated steel strip comes into contact with the guide roll. A molten metal plating method characterized by first guiding and plating a plated steel strip so as to be positioned in a bath of a small bathtub, and at the same time supplying molten plated metal in the molten metal plating bath to the small bathtub.