JPH06330273A - Production of hot dip coated steel sheet and its production - Google Patents

Abstract

PURPOSE:To produce the hot dip coated steel sheet with excellent productivity by allowing the temp. of a hot rolled steel sheet to fall down to an adequate tempt., then removing the oxide scale on the surfaces in an inert gaseous atmosphere and subjecting the steel sheet to hot dip metal coating. CONSTITUTION:The high-temp. hot rolled steel sheet is directly sent to a cooling machine 6 of a hot dip coating line and its temp. is allowed to fall down to the adequate temp. necessary for coating the steel sheet with molten metal at the time of plating the surfaces of the high-temp. hot rolled steel sheet W produced by hot rolling with the metal, such as Zn, Sn, Pb or Al. This steel sheet is then sent into a casing 1 of the inert gaseous atmosphere of inert gas, such as N2 or others, from an inert gaseous atmosphere supplying device 4 and the oxide scale on the steel sheet surfaces is removed by shot blasting in this casing 1; thereafter, the steel sheet is plated with the molten metal with excellent adhesive power by a hot dip metal coating machine in the clean state in which the surfaces are not reoxidized by the inert gaseous atmosphere. The hot rolled steel sheet is subjected to the hot dip metal coating by reheating after the steel sheet is coiled and cooled and, therefore, the hot dip coated steel sheet is produced with the good thermal efficiency and productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the surface of a steel sheet containing zinc,
The present invention relates to a method and apparatus suitable for hot-dip plating of metals such as tin, lead and aluminum.

[0002]

2. Description of the Related Art Conventionally, when hot-dip galvanized steel sheets are manufactured, a rolled steel sheet in a high temperature state obtained by rolling crude steel is wound by a winding machine and stored as a coil material.
The coil material is again drawn out, the oxide scale generated on the surface of the steel sheet is removed by shot blasting, and then the steel sheet is heated to an appropriate temperature for hot dipping.
Therefore, the conventional hot-dip galvanized steel sheet production involves many steps for handling rolled steel sheets, which results in poor productivity and takes time to obtain the final product.

On the other hand, in the industry, from the viewpoint of improving productivity, the appearance of an apparatus for continuously performing rolling to hot dipping at once is demanded, but a steel sheet in a high temperature state is blasted to remove an oxide scale. However, since it is in a state of contacting with air at a high temperature, there is a problem that an oxide scale is generated again and the hot dip plating process cannot be performed, so that it has not been put into practical use. The present invention has been made in view of the above problems, and an object of the present invention is to provide a method and an apparatus for manufacturing a hot-dipped steel sheet in a high temperature state before winding to produce a hot dip plated steel sheet.

[0004]

[Means for Solving the Problems] In order to achieve the above-mentioned problems, a method for producing a hot-dip steel sheet according to the present invention comprises a step of cooling a steel sheet in a high temperature state by rolling to an appropriate temperature,
A step of introducing the steel sheet cooled to the appropriate temperature into an inert gas atmosphere to remove the oxide scale generated on the surface of the steel sheet by shot blasting, and the oxidation in the inert gas atmosphere. The step of performing hot dip plating on the surface of the steel sheet from which the scale has been removed is characterized by comprising:
A cooling machine for lowering the temperature of the rolled steel sheet to an appropriate temperature is arranged in the middle of the moving line of the rolled steel sheet, and a shot steel blasting machine and a hot dip galvanizing machine are arranged downstream of the cooling machine and the shot blasting machine. Further, the hot dip coating machine is surrounded by a casing that creates an inert gas atmosphere.

[0005]

According to the present invention, by adopting the above-mentioned solution means, the rolled steel sheet in the high temperature state is
After being cooled to an appropriate temperature, introduced into an inert gas atmosphere, shot-blasted to remove the oxide scale, and then subjected to hot dip plating in an inert gas atmosphere in which the oxide scale is not regenerated. As a result, the hot dip plating process can be performed in a series of lines from rolling of crude steel to winding.

[0006]

[Test Example] As shown by the solid line in FIG. 1, a shot blasting machine 1 and a hot dip coating machine 2 are sequentially arranged, and the shot blasting machine 1 and the hot dipping machine 2 are casing 3.
The shot blasting machine 1, the hot dip galvanizing machine 2 and the casing 3 are made to coincide with each other through lines of the steel plate W (composed of a driving roller (not shown)), and the casing 3 is surrounded by The casing 3 is kept in an inert gas atmosphere by communicating with the active gas supplier 4, and the steel plate (100
(0 × 1000 × 2.3 mm thickness) heated to various temperatures of 400 to 800 ° C. in a heating furnace is fed into the above-mentioned apparatus, and the results of performing the plating by the shot blasting treatment and the hot dipping treatment are shown in the table below. Shown in 1. For the evaluation of the plating characteristics, the quality was judged by comparing the uniformity of the plating layer, the thickness of the film with pinholes, and the like with those of the conventional method.

[0007]

[Table 1]

From the above results, the steel sheet heated to a temperature slightly higher than the temperature of the steel sheet required for the hot dip coating is shot blasted in an inert gas atmosphere to be discharged.
It was confirmed that good plating can be performed by performing the hot dipping treatment by lowering the temperature of the steel plate to a temperature range suitable for hot dipping at the same time as ringing. In the above test example, a steel plate having a thickness of 1000 × 1000 × 2.3 mm was used, but in an actual production line, a continuous long high temperature steel plate is continuously treated, and a case for creating an inert gas atmosphere is used. A cooler 5 for cooling and lowering the steel plate W to an appropriate temperature is arranged upstream of the thing 3 as shown by a dotted line to function as a device.

[0009]

According to the present invention, as is apparent from the above description, the steel sheet in a high temperature state is cooled to an appropriate temperature and introduced into an inert gas atmosphere for shot blasting and hot dipping. The oxide scale on the surface of the steel sheet is completely removed, and hot-dip galvanizing is carried out in an inert gas atmosphere that does not regenerate. It is significant that it has the effect of greatly improving it.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a test example of the present invention.

[Explanation of symbols]

 1 Shot blasting machine 2 Hot dip coating machine 3 Casing 4 Inert gas supply machine 5 Cooling machine

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[Procedure amendment]

[Submission date] March 11, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title: Method and apparatus for manufacturing hot dip plated steel sheet

Claims (2)

[Claims] 1. A step of lowering the temperature of a rolled steel sheet in a high temperature state to a proper temperature, and introducing the steel sheet cooled to the proper temperature into an inert gas atmosphere and performing shot blasting treatment on the surface of the steel sheet. Hot dip plated steel sheet, which comprises a step of removing the oxidized scale that has been formed, and a step of performing hot dip coating on the surface of the steel sheet from which the oxidized scale has been removed in the inert gas atmosphere. Manufacturing method 2. A cooling machine for lowering the temperature of the rolled steel sheet to an appropriate temperature is arranged midway along the line for moving the rolled steel sheet, and a shot blast machine and a hot dip galvanizing machine for penetrating the rolled steel sheet are arranged downstream of the cooling machine. An apparatus for producing a hot-dip plated steel sheet, characterized in that the shot blasting machine and the hot dip coating machine are surrounded by a casing that creates an inert gas atmosphere.