JPS62192570A - Hot dip metal coating method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

[Conventional technology]

In continuous hot-dip metal plating, a continuous plating line is used that can appropriately switch between different plating steps such as zinc plating and red plating. Conventionally, the following method has been adopted for switching plating on such a continuous line.

(When performing cutting using two plating tanks, the molten metal used is pumped out and the plating tank is emptied, and then other metal is put in and melted.

(2) Two plating tanks are prepared and used selectively by moving the plating tank to the plating position depending on the metal to be used.

(3) Two plating tanks are installed in tandem at separate locations to melt different metals in each tank, and when switching between them, the pass line of the strip is switched.

[Problem that the invention seeks to solve]

However, among these switching methods, method (11) requires a long time to replace the molten metal because the plating bath melts and holds about 300 tons of molten metal.
The drawback is that production has to be halted during this period. In addition, methods (2) and (3) have the fundamental problem of having to install two large-capacity plating tanks as described above, and the equipment and work required for switching is also a major loss. It has no choice but to become a thing.

As described above, in the past, it has not been possible to efficiently switch the plating from the intermediate set, such as when the plating tank itself has a large capacity.

Recently, there has been an increasing demand for materials with different types of plating layers on the front and back sides that are suitable for each corrosive environment, but until now there has been no plating method for obtaining such steel plates relatively easily.

The present invention was made in view of such conventional problems,
The purpose of the present invention is to provide a molten metal plating method that can perform plating with a small amount of molten metal retained, and therefore can easily switch plating, and can also perform true rock plating on the front and back sides relatively easily. .

Means for Solving Problem C] For this reason, the present invention supplies molten metal in a raised manner at the lower part of the horizontal or inclined pass line portion of the strip, and brings the strip into contact with the molten metal. plate the surface of the strip, then invert the strip with its non-plated surface in contact with a reversing roll, thereby supplying the molten metal by straining it so as to raise it at the bottom of the horizontal or inclined pass line portion of the strip; Its basic feature is that the other side of the strip is plated by bringing the strip into contact with the molten metal.

〔Example〕

FIG. 1 and FIG. 2 show an embodiment of the present invention.
la) (lb) (tc) is the deflector roll, (2
A) (2B) is a molten metal supply nozzle that supplies molten metal (3) in an upward heaping manner, (4 people) (4B)
(5) is a metal melting tank, and (5) is a pump for supplying molten metal from these metal melting tanks to a molten metal supply nozzle.

The strip (6) first passes through the deflector roll (1a) (1
b) A horizontal pass line portion (A) is formed between the two.

A molten metal supply nozzle (2A) is arranged at the bottom of this horizontal pass line part (A).
Molten metal (3) is supplied from A) in a rising manner, and the lower surface of the strip (6) comes into contact with this molten metal (3), so that one side of the strip (6) is plated.

The strip (6) is then reversed with its non-plated side wound around a deflector roll (lb) (reversing roll);
Horizontal pass line part C between deflector roll (1c)
B) is formed. A molten metal supply nozzle (2B) is also arranged at the bottom of this horizontal pass line part (B), and the molten metal (3) is supplied from this molten metal supply nozzle (2B) in a rising manner, and the strip (6 ) comes into contact with the molten metal (3) on its lower side, and from this the other side of the strip is also plated.

At the position facing the deflector roll (lb) (lc) through which the strip (6) passes after each single-sided plating.

A gas jet device fft (7) for adjusting the coating amount is provided, and a gas jet is sprayed onto the plating surface at the longitudinal center position where the strip (6) is wound around each deflector roll (1), thereby adjusting the coating amount. It will be done.

Each of the molten metal supply nozzles (2) is supplied with molten metal (3
), and the molten metal (3) not deposited on the strip (6) is returned to the melting tank (4) by suitable recovery means.

In addition, when contacting molten metal (3), strips and protrusions (
The surface temperature in step 6) is heated above the melting point of the molten metal, so the plating atmosphere must be kept inert so as not to damage the surface condition activated in the previous reduction and annealing process. be.

Each pass line portion on which single-sided plating is performed is not limited to a horizontal pass line, but may be appropriately sloped.

In this method of the present invention, the amount of molten metal retained can be significantly reduced compared to the conventional plating method using the cypress immersion method, making it extremely easy to switch between plating between different types of molten metal. can be done.

Furthermore, by plating each single side with different types of molten metal using the molten metal supply nozzles (2A) (2M), it is possible to easily produce a steel plate with different types of plating on the front and back sides.

One implementation condition of the method of the present invention is shown below.

CD double-sided homogeneous plating A cold-rolled steel sheet that had been reduced and activated with H2 gas was galvanized under the following conditions while being maintained in an N3 gas atmosphere.

・Strip: 500℃ width, 0.6 thickness ・Slit nozzle = 50% x 1000 yen.

Medium retention zinc i: 800 per slit nozzle?・Zinc transfer bong: Impeller set transfer pump O zinc temperature = 46
0℃・Strip temperature: 470℃ [■] Double-sided dissimilar plating, Zn in one melting tank, At5 in the other metal melting tank
%-Zn bath, H plating was performed on one side and 115%-Zn plating was performed on the other side under the following conditions.

Urn strip: 500vmrp, 0.6'X thickness
Slit nozzle: 50%X1tlOO%・Retained zinc amount 2800Kg・Retained aluminum-zinc amount: 780Kf・Zinc transfer pump: Impeller set transfer pump Zinc temperature: 460℃ ・Aluminum-zinc temperature: 460℃ ・Strip temperature: 47QC [ [Effects of the Invention] According to the present invention described above, appropriate l
This plating can be done.

This has the effect of making it easy to change plating in a continuous plating line that performs two or more types of plating.In addition, by plating each single side with a different type of molten metal, one front and back side can be plated differently. Steel plates can be manufactured relatively easily.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 show an embodiment of the present invention, with FIG. 1 being a side view and FIG. 2 being a front view. In the figure, (ia) (lb) (tc) is a deflector roll, (2A) (2I5) is a molten metal supply nozzle, (6n is a strip, (A) CB) is a horizontal pass line part. Patent applicant Nippon Kokan Co., Ltd. No. 1 Figure 6 2A

Claims (2)

[Claims] (1) Plating one side of the strip by supplying molten metal in a heaping manner at the bottom of the horizontal or inclined pass line portion of the strip and bringing the strip into contact with the molten metal, and then plating the strip on its unplated surface. The strip is inverted so that its surface is in contact with a reversing roll, molten metal is supplied in a heaping manner at the bottom of the horizontal or inclined pass line portion of the strip, and the other side of the strip is brought into contact with the molten metal. A molten metal plating method characterized in that the surface of the molten metal is plated. (2) A molten metal plating method according to claim 1, characterized in that each side of the strip is brought into contact with a different type of molten metal so that both sides of the strip are plated with different types.