JPH0533112A - Method and apparatus for manufacturing alloyed molten zinc plated steel sheet - Google Patents

Abstract

(57) [Summary] [Structure] Steel plate 1 is passed through a hot dip zinc bath 2 to adjust the amount of zinc deposited, and then the cooling roll 9 causes insufficient alloying in the state where the solidification of the plating layer is not completed. After the surface of the edge overcoat portion is rapidly cooled to increase the plate surface emissivity of the overcoat portion, alloying treatment is performed in the alloying furnace 6. [Effect] According to the present invention, alloying of the steel sheet edge portion can be effectively promoted, and the alloy can be uniformly alloyed in the sheet width direction. In addition, it is possible to eliminate the drawbacks of the conventional products in which the powdering resistance is deteriorated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing an alloyed hot dip galvanized steel sheet by heating and heat-retaining a steel sheet immediately after hot dip galvanizing mainly by radiant heat transfer.

[0002]

2. Description of the Related Art Conventionally, when a steel sheet immediately after hot dip galvanizing is heated and retained mainly by radiant heat to produce an alloyed hot dip galvanized steel sheet, the edge portion of the steel sheet tends to be overcoated, There is a problem that alloying of the edge portion does not proceed sufficiently. As a countermeasure against this, conventionally, the operation has been carried out so that the edge portion where the alloying has not progressed the most is within the lower limit of alloying, so that there is a problem that the alloying progresses too much and the powdering resistance is poor.

Therefore, for example, as disclosed in Japanese Patent Laid-Open No. 59-31858, a method has been developed in which a burner dedicated to the edge portion is installed and only the edge portion is heated. But this method
It has a drawback that it can only heat a fixed distance from the edge of the steel sheet and cannot cope with the case where the alloying failure portion of the edge changes. Further, there is a problem that the effect is small because the heating length cannot be long.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for manufacturing an alloyed hot-dip galvanized steel sheet which solves the above problems.

[0005]

According to the method of the present invention, after the steel sheet is passed through a molten zinc bath to adjust the zinc deposition amount, the alloying is not sufficiently alloyed by a cooling roll in the state where the solidification of the plating layer is not completed. After quenching the surface of the overcoat part of the steel plate edge to increase the plate surface emissivity of the overcoat part,
A method for manufacturing an alloyed hot-dip galvanized steel sheet, which is characterized by performing an alloying treatment in an alloying furnace, and an alloy in a plate width direction by an alloying degree meter during or after the alloying treatment. It is characterized in that the galvanized distribution is detected, and the plated steel sheet is rapidly cooled by a cooling roll based on the detected alloying distribution.

In the apparatus of the present invention, a steel sheet is passed through a molten zinc bath, the zinc adhesion amount is adjusted by a zinc adhesion amount adjusting device such as gas wiping, and then an alloying treatment is performed in an alloying furnace. In the apparatus for producing hot-dip galvanized steel sheet, a cooling roll is provided between the zinc adhesion amount adjusting apparatus and the alloying furnace to rapidly cool the surface of the overcoat portion of the steel sheet edge to increase the plate surface emissivity. It is an apparatus for producing an alloyed hot-dip galvanized steel sheet, which is also a cooling method in which the cooling roll allows a cooling medium to pass through, and a variable cooling range in the width direction of both edges of the plated steel sheet. Further, an adjusting device for the cooling range in the width direction of both edges of the plated steel sheet by the cooling roll, and a command for controlling the adjusting device are sent, and an alloying distribution in the plate width direction is provided. Inspection That it comprises a alloyed meter that is characterized in.

[0007]

[Operation] The temperature of the hot-dip galvanized steel sheet in the alloying furnace is mainly heated by radiation rather than by convection of the gas in the furnace. On the other hand, the surface of the hot-dip galvanized steel sheet after the gas wiping exhibits luster, so that the radiant heat is not efficiently absorbed. This is because the higher the plate surface emissivity, the better the heat absorption in the alloying furnace.

Here, the inventors of the present invention have come to the conclusion that it is possible to improve the absorption of radiant heat by increasing the plate surface emissivity of the hot-dip galvanized steel sheet after gas wiping. Has reached the present invention. Generally, as a spangle erasing method for non-alloyed hot dip plated steel sheet, the surface of the hot dip plated steel sheet is sprayed with a spray liquid while it is not solidified to rapidly cool it, thereby making the plating film fine crystals to have a gloss level. It is being dropped.

The present invention is an application of this, and the principle of the present invention is to increase the plate surface emissivity of the edge portion by rapidly cooling the edge portion of the steel sheet, which tends to be insufficiently alloyed, with a cooling roll. The insufficient alloying of the edge portion is solved by heating the edge portion from the other in the alloying furnace.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of an embodiment of the present invention. Figure 2
FIG. 3 is a perspective view of a main part of an embodiment of the present invention. FIG. 3 is a partial cross-sectional perspective view of an embodiment of the cooling roll of the present invention.

1 to 3, 1 is a plated steel plate, 2 is a zinc bath, and 3 is a zinc bath. Reference numeral 4 is a wiping nozzle for adjusting the amount of plating adhered, and 5 is an edge detection device for the plated steel sheet 1. 6 is an alloying furnace, 7 is a heating zone, and 8 is a heat retaining zone. Reference numeral 9 is a cooling roll for rapidly cooling the plating layer, which is installed at a location where the solidification of the plating layer is not completed.
An inner pipe 10 is provided inside the cooling roll 9 and has a double pipe structure. A pair of left and right partition plates 11a and 11b are fixed near the center of the inner pipe 10, and
Partition plates 12a and 12b, which are movable along the inner tube 10, are mounted on the outer sides of 11a and 11b, respectively. Partition plates 12a, 12b
A hole 13 that communicates with the outside of the inner pipe 10 and a hole 14 that communicates with the inside of the inner pipe 10 are provided in each.

Reference numeral 15 is a cooling roll driving and partition plate position adjusting device. A cooling medium such as cooling water or air is supplied to the inside of the cooling roll 9 from the left and right sides of the cooling roll 9,
Circulate separately on the left and right. That is, the cooling medium is separately supplied from the left and right sides of the cooling roll 9 to the outside of the inner pipe 10 by the pipe 16, cools the plated steel sheet 1, passes through the inside of the inner pipe 10 through the holes 13 and 14, and from the pipe 17. Is discharged.

At this time, the positions of the partition plates 12a and 12b are adjusted to control the cooling rate in the plate width direction,
The alloying treatment can be performed uniformly in the plate width direction. That is, in the cooling roll 9, the surface state is changed (disappeared) and the plate surface emissivity is increased only in the edge portions of the plated steel sheet that is rapidly cooled by contacting the left and right regions in which the cooling medium circulates. As a result, the amount of heat rise in the edge portion in the alloying furnace increases, alloying proceeds more than other portions, and the alloying treatment can be performed uniformly in the plate width direction.

The inlet temperature of the cooling medium supplied to the cooling roll 9 is preferably adjusted. Further, in the present embodiment, the alloying degree in the plate width direction is detected by the alloying degree meter 18,
The partition plates 12a and 12b are automatically positioned. Next, specific examples of the present invention will be described.
Using the apparatus shown in FIGS. 1 to 3, a plate thickness of 1.0 mm, a plate width of 1200 mm, a line speed of 60 m / min, a bath temperature of 460 ° C., an adhesion amount of 45/45 g / m, a heat retention temperature of 500 ° C., and a holding time of 10 seconds were used. FIG. 4 shows the result of heating zone outlet side plate temperature distribution in the sheet width direction, and FIG. 5 shows the result of alloying degree (wt%) distribution. The results when the cooling roll of the present invention is not used are also shown in FIGS.

It can be seen from FIG. 5 that in the case of the present invention, alloying at the edge portion was promoted and the insufficient alloying was eliminated. FIG. 6 shows the results of controlling by detecting the alloying degree distribution in the plate width direction. The results when the cooling roll of the present invention is not used are also shown in FIG. It can be seen that by adjusting the position of the partition plate in the cooling roll of the present invention, it becomes possible to sufficiently respond to the fluctuation in the range where the alloying has not progressed from the edge.

[0016]

As described above, according to the present invention, the alloying of the edge portion of the steel sheet can be effectively promoted and the alloy can be uniformly alloyed in the sheet width direction. In addition, it is possible to eliminate the drawbacks of the conventional products in which the powdering resistance is deteriorated. Also, since the heat absorption rate has increased overall, there is also the advantage of reducing the basic unit.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

FIG. 2 is a perspective view of a main part of an embodiment of the present invention.

FIG. 3 is a partial cross-sectional perspective view of an embodiment of the cooling roll of the present invention.

FIG. 4 is a graph showing a heating zone outlet side plate temperature distribution in the plate width direction.

FIG. 5 is a graph showing the alloying degree distribution in the plate width direction.

FIG. 6 is a graph showing the effect of controlling the width direction of the cooling roll of the present invention.

[Explanation of symbols]

1 plated steel sheet 2 zinc bath 3 zinc bath 4 Wiping nozzle 5 Edge detector 6 alloying furnace 7 heating zone 8 tropical heat 9 cooling rolls 10 inner tube 11a Partition plate 11b Partition plate 12a Partition plate 12b partition 13 holes 14 holes 15 Cooling roll drive and partition plate position adjustment device 16 piping 17 Piping 18 Alloying degree meter

Claims (5)

[Claims] 1. A steel sheet is passed through a hot-dip zinc bath to adjust the amount of zinc deposited, and then the surface of the overcoat portion of the steel sheet edge where alloying is insufficient is cooled by a cooling roll in a state where the solidification of the plating layer is not completed. A method for producing an alloyed hot-dip galvanized steel sheet, which comprises quenching and increasing the plate surface emissivity of an overcoat portion, and then performing an alloying treatment in an alloying furnace. 2. During the alloying treatment or after the alloying treatment,
The alloyed hot-dip galvanized steel sheet according to claim 1, wherein the alloying distribution in the plate width direction is detected by an alloying degree meter, and the plated steel sheet is rapidly cooled by a cooling roll based on the detected alloying distribution. Manufacturing method. 3. Production of an alloyed hot dip galvanized steel sheet in which a steel sheet is passed through a hot dip zinc bath, the zinc adhesion amount is adjusted by a zinc adhesion amount adjusting device such as gas wiping, and then an alloying treatment is performed in an alloying furnace. In the apparatus, an alloy characterized in that a cooling roll is provided between the zinc adhesion adjusting device and the alloying furnace to rapidly cool the surface of the overcoat portion of the steel plate edge to increase the plate surface emissivity. Equipment for producing hot-dip galvanized steel sheet. 4. The alloyed molten zinc according to claim 3, wherein the cooling roll is a cooling system in which a cooling medium is passed inside, and the cooling range in the width direction of both edges of the plated steel sheet is variable. Manufacturing method of plated steel sheet. 5. An adjusting device for adjusting a widthwise cooling range of both edges of a plated steel sheet by a cooling roll, and an alloying degree meter for sending an instruction for controlling the adjusting device and detecting an alloying distribution in the plate width direction. The manufacturing apparatus of the alloyed hot-dip galvanized steel sheet of Claim 3 or 4 characterized by the above-mentioned.