JPH036358A - Method for controlling deposition amount of molten metal plating - Google Patents

Abstract

PURPOSE:To uniformly and surely control the coating wt. of a molten metal for hot dip plating without scattering the molten metal by moving control plates for controlling the coating wt. of a molten metal for hot dip plating arranged on the surface of a molten metal bath for hot dip plating to regulate the gap between each of the control plates and a steel strip at the outlet side of the bath. CONSTITUTION:Control plates 3, 3a for controlling the coating wt. of a molten metal for hot dip plating are arranged on the surface of a molten metal bath 2 for hot dip plating over the entire width of both sides of a steel strip 1 at the outlet side of the bath 2. The steel strip 1 hot dip plated in the bath 2 rises between the control plates 3, 3a. At this time, the gap between each of the plates 3, 3a and the strip 1 is regulated by moving the plates 3, 3a and the coating wt. of the molten metal 2a for hot dip plating on the strip 1 is surely and uniformly controlled. The coating wt. can be made different on both sides of the strip 1 by regulating the height of the plates 3, 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for controlling the amount of molten metal plating deposited.

Conventional technology A well-known method for controlling the amount of adhesion in molten metal plating is to introduce a metal strip such as a steel strip into a plating bath, pull it upwards, and use a gas wipe to control the amount of adhesion when the plated metal is not solidified. ing.

In this type of control method, it is difficult to make the gas discharge pressure uniform across the steel strip gold mine, which results in uneven wiping of the plated metal, which impairs quality, and also prevents the gas from reaching the plated surface. The plated metal is scattered due to the collision, and this may adhere to the surface of the plated steel strip after adhesion control, or the scattered plated metal may harden and fall to the bath surface, becoming floating dross and contaminating the bath. This deteriorates the plated surface of the steel strip.

Further, there are drawbacks such as high gas injection noise, which worsens the working environment.

For this reason, it has been disclosed that the amount of plating metal deposited is controlled by the electromagnetic force of a linear motor (Japanese Patent Laid-Open No. 81-227158, etc.), but the wiping power is weak, the power consumption is large, and the cost is high. There are disadvantages such as becoming

Problems to be Solved by the Invention The present invention has been made to advantageously solve these drawbacks.

Means for Solving the Problems The present invention provides a means for solving the problems by applying an I
1. A method for controlling the coating amount of molten metal plating, comprising adjusting the gap between the plated metal coating amount control plate and the steel strip by moving the control plate.

and over the gold mine on both sides of the steel strip exit side on the surface of the molten metal plating bath,
The present invention relates to a method for controlling the amount of deposited metal plating, which is characterized by adjusting the height of a plated metal deposit amount control plate.

In other words, hot-dip metal plating in wood invention includes zinc, aluminum, tin, turn metal, etc.Also, alloy plating can be performed by adding small amounts of other metals to these metals, and after plating, if necessary, It is also possible to perform alloying treatment by heat treatment.

Next, the mechanism of controlling the coating amount of plating according to the invention will be explained with reference to the drawings.

In FIG. 1, a steel strip 1 is immersed in a molten metal plating bath 2, moves upward after plating, and is pulled up onto the surface of the plating bath 2. At this time, the plated metal 2 is attached to both sides of the steel strip 1. Therefore, a plating metal adhesion control plate 3.3a (for example, a material having heat resistance and corrosion resistance such as ceramics can be used) is arranged on both sides of the steel strip 1 exit side of the surface of the plating bath 2. The amount of plating metal deposited on the steel strip 1 is controlled by adjusting the gap between the steel strip 3a and the steel strip 1.

That is, when the steel strip 1 passes between the control plates 3.3 and 3.3, it receives a reaction force from the accompanying plated metal 2a, which is a so-called hydroplaning phenomenon, causing the control plates 3.3 and 3.
Since it moves while being held in the center between 3&, the amount of plating deposited on both sides of the steel strip 1 can be controlled to be almost uniform.

Therefore, by adjusting the gap between the control plate 3.3a and the steel strip 1 by adjusting the movement yJ, the amount of plating deposited on the steel strip 1 can be accurately controlled.

In other words, it is possible to reliably control the coating amount over a wide range of 20 to 90 g/fl12, and the sheet passing speed can be increased without scattering of the plated metal due to the coating amount control, thereby significantly improving productivity.

In addition, when performing so-called differential thickness plating, which changes the amount of plating on the front and back surfaces of the steel strip 1, as shown in FIG.
As shown in the figure, the other control plate 3a is made high with a uniform gap between the control plate 3.3a and the steel strip 1, so that the steel strip 1 surface on the control plate 3a side is connected to the steel strip 1 on the control plate 3 side. The amount of coating can be made thicker than the surface.

The reason is that the plated metal between the steel strip 1 and the control plate 3.
(Bath) Depending on the growth rate of the viscous flow, the velocity distribution within the plating layer discharged from the wiping zone along with the surface of the steel strip 1 differs.The longer the control plate is, the longer the viscous flow is held in the plane Grows long and full.

Therefore, as shown in FIG. 5, as the velocity distribution approaches a linear distribution, even points far away from the steel strip have a high linear velocity, and the range where the surface tension with the control plate edge portion can be overcome is expanded.

Therefore, a large amount of molten metal remains in the steel strip so that it can be made thicker.

Example Next, examples of the present invention will be described.

Example 1 Continuous hot-dip galvanizing was carried out as follows.

(1) Plating bath composition: Normal plating bath (2) Plating bath temperature: 480℃ (3) Plating material: Steel strip (Q, 8mm thick, 800m+
(4) Sheet threading speed: Loom/min (5) Plating metal adhesion amount control board: See Figure 3 a, a
: 30mm, b, b' : 20mm,
R, R': 5mm (6) Gap between plated metal coating amount control plate and steel strip = 1.0 layer resin (common gap on both sides of m band) When zinc plating was applied continuously in this way, both sides were uniformly coated. The amount of adhesion could be controlled to Bog/m2 (one side).

Example 2 It was carried out under the same conditions as Example 1, and the height of the plated metal adhesion control plate was changed as shown below to perform differential plating.

Plating metal adhesion amount control plate: See Figure 4 a: 30mm, a': 40mm, b
: 20mm, b': 30+a+m.

R, R: 5mm When plating was applied in this way, the steel strip surface on the control plate 3a side Bog/r12. Steel strip surface on control plate 3 side 50g/m
It was possible to perform plating with a difference in thickness of 2.

Effects of the Invention The present invention enables high-speed threading without the occurrence of splash due to coating amount control, improving productivity, and ensuring uniform coating amount control over the entire plated material. Quality can also be improved.

Furthermore, compared to gas wipes and the like, it does not require energy to control the amount of adhesion, reducing costs.

Furthermore, almost no space is required for arranging the coating amount control plate, the supporting distance between the zinc roll at the bottom of the bath and the upper roll can be shortened, and warping in the width direction (zero warping) of the plated steel strip can be almost eliminated. Many excellent effects can be obtained, such as uniform alloying treatment in the alloying treatment furnace after plating.

[Brief explanation of drawings]

1 and 2 are explanatory views showing the present invention, FIGS. 3 and 4 are explanatory views of a control board showing an embodiment of the present invention, and FIG.
The figure is an explanatory diagram showing the relationship between the viscous flow of molten metal and the molten metal linear velocity distribution. 1. Gold steel belt, 2.. Fist plating bath, 2a... Accompanied plating metal, 3.3a... Adhesion amount control plate.

Claims (2)

[Claims] (1) A method for controlling the coating amount of molten metal plating, which comprises adjusting the gap between the plated metal coating amount control plate and the steel strip by moving the control plate over the entire width of both sides of the steel strip exit side of the surface of the molten metal plating bath. . (2) A method for controlling the amount of deposited metal plating, which comprises adjusting the height of a plated metal deposit control plate over the entire width of both sides of the steel strip exit side of the surface of the molten metal plating bath.