KR20030049752A - Stabilizing roll with anti-dross property - Google Patents

Abstract

PURPOSE: A dross resistant stabilizing roll in hot dip galvanizing pot is provided which suppresses floating dross inside the hot dip galvanizing pot from sticking to the stabilizing roll. CONSTITUTION: The dross resistant stabilizing roll in hot dip galvanizing pot comprises a sleeve(20a) of ceramic material; a shaft(20b) of metallic material inserted into the sleeve(20a) and shrinkage fitted to the sleeve(20a) at a high temperature as the shaft(20b) of metallic material has a higher thermal expansion coefficient than the sleeve(20a); and a flange(30) to which the sleeve(20a) and shaft(20b) are cohesively clamped by a bolt member(30b) at both ends of the shaft(20b), wherein the bolt member(30b) is perpendicularly clamped to the shaft(20b) by penetrating the circumferential surface of the flange(30), and the bolt member(30b) is clamped to the sleeve(20a) parallel to each other by penetrating the flange(30), and wherein the ceramic material is alumina (Al2O3), zircon (ZrO3), sailon, silicon nitride (SiN), mullite (Al2O3-SiO2), or a mixture thereof, and the metallic material is SUS316L or DCH-23.

Description

Stabilizing roll with anti-dross property in molten zinc bath

The present invention relates to a dross resistant Stabilizing Roll of a molten zinc bath (Zinc Pot, 100), and more particularly, to a dross (Zn) present in a zinc pot when continuous galvanizing of a steel sheet surface. The present invention relates to a stabilizing roll assembly comprising a ceramic sleeve, which is a non-metallic inorganic material, and an axis fitted thereto, in order to prevent quality defects from being caused by adhesion of Dross) to the roll surface.

In general, in the continuous galvanizing line, the greatest quality of the surface quality of the plated product is in the zinc pot, which means that the molten zinc is kept constant at a suitable temperature for plating. It is important.

In the zinc pot, as illustrated in FIG. 1, a sink roll (SINK Roll) 30 and an air knife (Air Knife), which change the direction of the steel sheet (Strip, 200) deposited on molten zinc after being heat treated in an annealing furnace, are shown in FIG. There are two stabilizing rolls 10 for preventing vibration of the steel sheet generated during the wiping of 300.

As shown in FIG. 2, the conventional stabilizing roll has a shaft 10a formed by centrifugally casting STS316L or DCH-23 developed in Japan in order to withstand high temperature and high corrosion. The welding method is mainly used, but this is because dross (Dross, 120, see FIG. 5), which is a zinc float, is attached to the surface of the roll to generate quality defects such as marks and scratches on the surface of the steel sheet. This has been a factor to shorten the roll service life.

This will be described in more detail as follows.

The iron (Fe) component eluted from the steel sheet reacts with the zinc (Zn), a composition of molten zinc, and the aluminum (Al) component to facilitate the control of the coating amount and to prevent the alloying delay after the plating treatment. Compounds such as -Zn-based, Fe-Al-based, and Fe-Zn-Al-based compounds (ie, dross 120) are formed.

The dross is scattered in the upper, lower, and baths in the zinc bath due to the specific gravity difference, and then agitated flow is formed by the movement of the steel sheet, the rotation of the sink roll, and the stabilizing roll, and then adhered to the roll and rotated. It generates fine scratches or defects that stick to the steel sheet. These defects become a criterion for changing the rolls according to the degree, which shortens the roll life.

In general, the degree of defects is increased in proportion to the use time, the sink roll deeply locked in the zinc port, the diameter is large, the rotational speed is low, the rotation speed is slow, and groove grooves on the surface of the roll to minimize the friction area with the steel sheet (30) Rather than), the defect factor due to the stabilizing roll 10 having a short time and distance from which the dross can be separated by molten zinc attached to the steel plate is located near the zinc pot bath surface.

On the other hand, it is very difficult to fundamentally prevent the production of dross generated in the zinc pot. In order to minimize the defects as described above, the method of removing dross of the molten zinc bath is melted in Japanese Patent Publication No. 96-188859. A technique for inducing a dross by installing an inclined plate inside a zinc bath is disclosed. In the Republic of Korea Patent Publication 1998-042952, a dross is removed by a mobile dross recovery device, but this may be effective in reducing the amount of dross. It was difficult to prevent dross from sticking.

In addition, Korean Patent 97-00488 has developed a method for coating the surface of the dross to prevent the dross from sticking to the stabilizer roll to prevent dross adhesion. The present inventors have also used dross and molten zinc on the surface using the same coating technology. Ceramic spray treatment was performed to minimize adhesion to the roll, but the spray layer on the surface of the roll was thin (0.1MM) and peeling occurred during use.However, dross adheres to the surface due to wear of the spray layer over time. As a result, marks (MARK) and scratches (SCRATCH) are generated on the surface of the steel sheet, which is a factor of shortening the roll life.

Therefore, it is judged that it is insufficient to effectively prevent defects caused by dross attachment by the conventional method, and thus, the present invention has been reached after the intensive study.

Accordingly, an object of the present invention is to provide a dross resistant stabilizing roll for inhibiting the floating dross in the molten zinc bath from adhering to the stabilizing roll.

1 is a schematic cross-sectional view of a zinc potrol.

2 is a cross-sectional view of the stabilizing roll according to the prior art

3 is a cross-sectional view of the stabilizing roll assembly according to the present invention

Figure 4 is an exploded perspective view of the stabilizing roll according to the present invention

5 is a cross-sectional view showing the stabilizing roll action according to the present invention.

In order to achieve the above object, the present inventors have repeatedly studied through data and several experiments on basic properties of dross and ceramic, and have come to the following conclusions.

The present invention assists the assembly of the sleeve and the shaft by assisting the assembly of the sleeve and the shaft to allow the roll to be rotated by the sleeve 20a in direct contact with the steel plate and the shaft through-assembled and fixed to the stabilizing roll arm. It consists of flanges to prevent slippage due to slipping.

That is, the present invention includes a sleeve made of a ceramic material and a metal insert inserted into the sleeve having a larger coefficient of thermal expansion than the sleeve and a flange for tightly coupling the sleeve and the shaft by bolt members at both ends of the shaft. Can be.

Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings.

3 and 4, in the dross resistant stabilizing roll of the present invention, the sleeve 20a which is in direct contact with the steel sheet is made of alumina, which is a ceramic material having low corrosion resistance and heat resistance and abrasion resistance, and having low reactivity with zinc. Al₂O₃), etc. (In addition, Zircon-ZrO₃, Mullite-Al₂O₃-SiO₂, Silol-Sailon, Silicon Nitride-SiN, etc. can be used) Pinholes for fixing the flange 30 on both sides Shaft (20b) is assembled with the sleeve using a corrosion-resistant STS316L (SUS316L) material and forms a pinhole for fixing the flange in the direction perpendicular to the axis of the flange assembly.

On the other hand, the flange 30 is fixed to the shaft 20b, and then fixed with a setting bolt 30b in a right angle direction, and having a fixing pin 30a in the axial direction, one of the holes formed in the ceramic sleeve 20a. The other side is fixed to the flange with nuts (Nut, 30c) to assist in the assembly of the sleeve and the shaft to prevent slipping due to the sleeve and the shaft in the abnormal assembly state.

The excellence in the dross resistance of the ceramic material is improved in the dross resistance through the thermal spray coating of the ceramic powder in the Republic of Korea Patent 97-00488, dross reduction by installing the ceramic auxiliary roll under the stabilizing roll in Korea Application No. 1999-57119 It has been described in detail in the previously filed patent.

However, the present invention can be said to be characterized in that it is embodied as a roll which is a direct driving body rather than an auxiliary characteristic by overcoming the fact that it cannot be manufactured as a roll due to the difficulty of integrating a metal and a nonmetal.

The assembly process will be described below.

When the outer diameter of the shaft 20b is naturally fitted due to the tolerance sufficient for the inner diameter of the ceramic sleeve 20a, the flanges 30 which are shrinked on both sides of the shaft are fixed to the sleeve by the fixing pins 30a, and the set bolts 30b are fixed. The assembly is completed by setting the flange to the shaft and then attaching the support arm to the bearing (not shown).

The assembled stabilizer roll is preheated by gradual heating in a preheating furnace of the same temperature condition (450 ± 10 ° C) before being deposited in the molten zinc bath. In this process, the ceramic sleeve 20a and the shaft having different thermal expansion coefficients are Between 20b, it becomes the assembly state of an interference fit, and it becomes possible to play a role as a roll.

In other words, the temperature coefficient of use is high as 1000 ~ 2000 ℃ and the coefficient of thermal expansion is low (7 X 10 ^-6 / ℃) at about 450 ℃ ceramic sleeve 20a almost no change in diameter and the coefficient of thermal expansion is higher than that of ceramic (16 X 10 ^-6 / ℃) The shaft 20b made of STS316L has a large amount of expansion, so that a negative tolerance occurs between the sleeve and the shaft, so that it is fixed. (50 ± 5 ° C / Hr) will occur, but the short time to deposition will prevent the molten zinc from entering between the sleeve and the shaft.

In addition, if the fitting cannot be made in the port due to unexpected reasons such as machining and abrasion of the sleeve and shaft, the assembly pin is assisted by fixing pin (bolt member) to prevent slipping of the sleeve and shaft. It is to be fixed by the setting bolt (30b) to prevent the separation from the flange 30 is sewn.

Meanwhile, the stabilizing roll assembled as described above has a repulsive force acting to push each other between the metal material and the dross 120 due to the characteristics of the surface ceramic sleeve 20a (see FIG. 5). It can be prevented from adhering to the rolling roll position, thereby preventing the dross floating in the bath and adhering to the roll surface when rotating in the molten zinc bath.

Stabilizing rolls acting as described above can be used for a long time and the replacement factor is reduced due to poor surface, but is composed of a sink roll frame and a set. If the replacement factor is caused by wear or tearing of the rotating part of the stabilizer roll, the sleeve 20a may be caused by contraction of the shaft 20b by naturally cooling the stabilizer roll drawn from the molten zinc bath at room temperature. After removing the flange 30 fixing pin (30a) and the sleeve auxiliary setting bolt (30b) and then hitting the shaft will be able to disassemble the roll without applying a large external force.

As described above, according to the present invention, the dross 120 suspended in the molten zinc bath is prevented from adhering to the surface of the steel sheet 200 and the stabilizing roll, thereby preventing quality defects such as marks and scratches. On the other hand, it is possible to obtain a practical effect of extending the service life of the stabilizing roll by eliminating replacement factors due to poor roll surface.

Claims (3)

In the stabilizing roll in the molten zinc bath, a sleeve made of a ceramic material 20a and a metal material inserted into the sleeve 20a and having a thermal expansion coefficient greater than that of the sleeve 20a are fixed to the sleeve 20a at a high temperature. Hot dip zinc bath comprising a flange (30) for fastening the sleeve (20a) and the shaft (20b) by a bolt member at both ends of the shaft (20b) and the shaft (20b) of the Dross resistant stabilizer roll. The method of claim 1, wherein the bolt member 30b penetrates the circumferential surface of the flange 30 to be perpendicular to the shaft 20b, and the bolt member 30a penetrates the flange 30 to the sleeve. A dross resistant stabilizing roll in a molten zinc bath, characterized in that it is fastened in parallel with (20a). According to claim 1 or 2, wherein the ceramic material is alumina (Al₂O₃), zircon (ZrO₃), silol (Sailon), silicon nitride (SiN) or Mullite (Al₂O₃-SiO₂) or a mixture thereof, The metal material is SUS316L or DCH-23, dross resistant stabilizing roll in the molten zinc bath.