JPH05195177A - Roll in molten-metal plating bath - Google Patents

Abstract

PURPOSE:To prevent the defective rotation of a roll used in a molten-metal plating bath in the non-driven state and to eliminate the scratching of the surface of a plated steel strip. CONSTITUTION:A steel roll 1 is used as the support roll in a molten-metal plating bath, and a ceramic film 2 is thermally sprayed over the surface of the roll 1. A dull 3 having 1-30mum roughness Ra is formed on the film 2 surface, or a chemically densified film consisting of a chromium-oxide ceramic layer is formed on the film 2 surface and then the dull is formed thereon. Consequently, the friction coefficient of the roll surface is increased, the contact force with a plated steel strip is enhanced, the friction coefficient between the roll and steel strip is increased, the roll is satisfactorily rotated even when not driven, and thereby the surface of the plated steel strip is not scratched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll in a molten metal plating bath, and particularly to a support generated due to a slip phenomenon between a support roll in a molten metal plating bath and a plated steel strip and wear of a roll bearing portion. The present invention relates to a roll in a molten metal plating bath, which can prevent the roll from rotating poorly and the scratches on the surface of the plated steel strip caused by the poor rotation of the support roll.

[0002]

2. Description of the Related Art In recent years, surface-treated steel sheets, such as hot-dip galvanized steel sheets, which are excellent in corrosion resistance, weldability and paintability, are rapidly growing in demand for applications such as automobiles, civil engineering, construction and home appliances. . As a method of manufacturing this surface-treated steel sheet,
Continuous hot-dip galvanizing, continuous hot-dip aluminum and other continuous hot-dip metal plating methods are mainly used.
In the continuous hot-dip metal plating method, as shown in FIG. 5, the steel strip 21 whose mechanical properties have been adjusted and whose surface has been cleaned and activated in a continuous furnace has a molten metal bath 23 through a snout 22.
The support roll 2 is immersed in the plating metal 24 inside and the direction of travel is changed by the sink roll 25 in the bath.
After being pulled up from the molten metal bath 23 via Nos. 6 and 27, a gas is jetted from the wiping nozzle 28 to squeeze out an excessive amount of the plating solution to adjust the amount of plating to be applied. After that, it is cooled to room temperature.

The rolls in the molten metal plating bath, such as the support rolls 26 and 27, which are immersed in the molten metal bath of the above-mentioned continuous metal plating method or used in a place where the molten metal is easily scattered, are the support rolls due to the constitution of the apparatus. 26, 27 and the plated steel strip 21 have a small wrap angle, resulting in a weak rotating force, or an increase in roll rotation resistance due to wear of the bearing portion of the roll, a decrease in friction force due to wear of the roll surface, Due to slippage caused by adhesion of foreign matter such as dross, rotation failure of the support rolls 26, 27 in the plating bath frequently occurs, causing surface defects such as scratches on the surface of the plated steel strip 21. In particular, when the support rolls 26 and 27 were used without being driven, the rotation failure was remarkable.

Conventionally, such a support roll in the molten metal plating bath is most generally a system in which a solid roll having a fluffy surface is driven by an external motor. FIG. 6 shows an example thereof, in which a drive motor 30 arranged outside the molten metal tank 23 drives the support roll 26 via a speed reducer 31, a joint 32, and a drive shaft 33. Further, the support of the support roll 26 in this system is, as shown in FIG. 7, a system in which the roll shaft 34 of the support roll 26 is supported by a cylindrical bearing metal 36 welded and fixed to the roll frame 35, as shown in FIG. A method of welding and fixing a semi-circular bearing metal 37 inclined at 45 degrees to the horizontal to the roll frame 35 (Japanese Patent Laid-Open No. 55-2730), or as shown in FIG.
Those in which 8, 39, 40 were welded and fixed to the roll frame 35 and the roll shaft retainer 41 were used.

On the other hand, as a roll in the hot-dip galvanizing bath, in a roll having a roll surface coated with a corrosion-resistant metal, a dull process is formed on the corrosion-resistant metal surface, and the surface is coated with a non-ferrous metal. (JP-A-57-210965) has been proposed. In addition, as a method for preventing surface defects of the plated steel strip due to the slip phenomenon of the roll and the steel strip in the molten metal plating bath and for preventing wear of the roll neck bearing, contact with the material to be plated in the molten metal plating bath. The supporting roll that rotates with
There has been proposed a non-drive rotation supporting method (Japanese Patent Laid-Open No. 3-253547) of a support roll for hot dip plating, in which the roll neck bearing is made of ceramic by subjecting the wear resistant metal to thermal spraying or overlaying.

[0006]

However, in the method of driving the support roll by an external motor, it is difficult to completely synchronize the peripheral speed of the support roll and the moving speed of the steel strip, and the steel strip and the roll are not synchronized with each other. The slip phenomenon occurs and scratches are generated on the surface of the steel strip, resulting in yield loss and chatter marks due to the drive system. Also,
In all of the conventional bearings, the fixing to the roll frame and the fixing of the bearings are usually performed by welding from the viewpoint of ensuring the strength of the bearing in the plating bath. Therefore, in repairing the bearing after pulling it up from the plating bath, the weld metal is removed by gouging or the like, and then the bearing is removed and disassembled. Therefore, in repairing the bearing, not only it takes a long time to remove from the roll frame and disassemble, but also the roll frame or the bearing metal is often damaged by gouging, which shortens the life of the bearing or requires a new repair work. There was a case that required. Further, the metallic bearing gold has a problem in wear resistance in a plating bath and a problem that the bearing life is short.

The roll disclosed in Japanese Patent Laid-Open No. 57-210965 has a main purpose of adjusting the surface of the roll for the purpose of evenly lifting the plating bath, and forming a dull on the surface of the corrosion-resistant metal. The surface is coated with a non-ferrous metal by thermal spraying or the like. Therefore, the roll is not formed with roughness on the outermost surface, and it is difficult to solve problems such as rotation failure in the plating bath. Further, the support roll in which the roll neck portion of the hollow roll disclosed in Japanese Patent Laid-Open No. 3-253547 has a heat-resistant and wear-resistant metal sprayed or overlaid, and the roll neck bearing is made of ceramic is caused by the bearing portion. Although the rotation failure of the roll can be prevented, the slip phenomenon due to the reduction of the frictional force between the roll and the plated steel strip cannot be prevented.

The object of the present invention is, in a bath roll used in a molten metal plating bath, particularly in a support roll, a rotation failure that occurs during use in a plating bath in a non-driving state, and plating resulting therefrom. It is an object of the present invention to provide a roll in a molten metal plating bath capable of preventing the occurrence of scratches on the surface of a steel strip.

[0009]

[Means for Solving the Problems] The inventors of the present invention have conducted an earnest test study in order to achieve the above object. As a result, the roll in the molten metal plating bath is made of a steel roll, and a dull having a predetermined roughness is formed on the surface of the ceramic coating sprayed on the surface of the steel roll, or a chromium oxide ceramic coating layer is formed on the surface of the ceramic coating. After forming the chemical densification treatment film or before forming the chemical densification treatment film, by forming a dull having a predetermined roughness, the friction coefficient of the roll surface becomes large and the plated steel in the plating bath is increased. It was clarified that the contact force with the strip was increased and the slip phenomenon between the roll and the plated steel strip could be prevented, and the present invention was reached.

That is, according to the present invention, the support roll in the plating bath which rotates in contact with the plated steel strip in the molten metal plating bath is a steel roll, and the surface of the steel roll is mainly composed of oxide or carbide. In the roll for hot-dip metal plating bath sprayed with a ceramic coating, the roll for hot-dip metal plating bath has a dull having a roughness of Ra 1.0 to 30 μm formed on the surface of the sprayed coating of the roll in bath.

Further, the support roll in the plating bath which rotates in contact with the plated steel strip in the molten metal plating bath is a steel roll, and the surface of the steel roll is a ceramic film containing oxide or carbide as a main component. In a roll in a bath for hot-dip plating of molten metal, a chemical densification treatment film consisting of a chromium oxide ceramics coating layer is formed on the surface of the thermal spray coating of the roll in the bath, and Ra is formed on the surface of the chemical densification treatment film.
It is a roll in a molten metal plating bath in which a dull having a roughness of 1.0 to 30 μm is formed.

Further, the support roll in the plating bath which rotates in contact with the plated steel strip in the molten metal plating bath is a steel roll, and the surface of the steel roll is a ceramic film containing oxide or carbide as a main component. In the roll in the molten metal plating bath sprayed with, the surface of the sprayed coating of the roll in the bath is Ra.
A roll in a molten metal plating bath in which a dull having a roughness of 1.0 to 30 μm is formed and then a chemical densification treatment film made of a chromium oxide ceramics coating layer is formed.

A roll in a molten metal plating bath, wherein the roll neck portion of the roll in the molten metal plating bath is subjected to thermal spraying or overlaying of heat-resistant and abrasion-resistant metal and the bearing of the roll is made of ceramics.

[0014]

The roll in the hot-dip galvanizing bath of the present invention is made of oxide or carbide ceramics by thermal spraying on the surface of a steel roll, or a mixture of them with a metal having excellent heat resistance and corrosion resistance such as Co and Ni. A chemical densification treatment film consisting of a chromium oxide ceramics coating layer is formed on the surface of the roll on which the thermal spray coating of cermet (hereinafter collectively referred to as cermet including this cermet) is formed, or on the surface of the roll on which the thermal spray coating is formed. After being formed, Ra 1.0 to
Since the dull having a roughness of 30 μm is formed, the friction coefficient of the roll surface becomes large, and the contact force between the roll and the plated steel strip in the plating bath can be increased.

Further, in the roll in the molten metal plating bath of the present invention, the roll neck is subjected to thermal spraying or overlaying of heat-resistant and wear-resistant metal, and the bearing of the roll is made of ceramics. The amount can be reduced and the bearing can be made sound. As a result, the roll in the molten metal plating bath of the present invention can prevent rotation failure in the molten metal plating bath, and prevents the occurrence of scratches on the plated steel strip surface due to the rotation failure of the roll in the bath, Product yield can be improved.

The ceramic sprayed coating on the surface of the steel roll according to the present invention may be formed by either a plasma spraying method or a high-speed gas flame spraying method. As the ceramic spray material, a ceramic such as an oxide or carbide, or they to Co, heat such as Ni, can be exemplified cermet consisting of a mixture obtained by mixing a metal excellent in corrosion resistance, the TiO ₂ 0. A containing 5 to 50%
l ₂ O ₃ -TiO ₂ solid solution composite are preferred. If the thickness of the sprayed coating is less than 20 μm, the effect of coating is not recognized, and if it exceeds 600 μm, the effect as a protective layer does not increase, and it takes a lot of time and cost for spraying, which is not economical and peels off. 20-600μ because the probability of wear increases
It is preferably m.

The formation of the chemical densification treatment film comprising the chromium oxide ceramics coating layer on the surface of the thermal spray coating of the in-bath roll of the present invention is carried out by immersing the in-bath roll having the thermal spray coating in an aqueous solution containing chromic acid. Alternatively, the surface of the roll is sprayed with an aqueous solution containing chromic acid in a bath. By this treatment, the surface of the sprayed coating is coated with chromic acid, and if pinholes are present in the sprayed coating, the chromic acid aqueous solution will penetrate into it. Then, the chromic acid film that covers the roll surface is applied at 200 to 500 ° C.
Heat to. By this treatment, the moisture in the chromic acid is evaporated and Cr ₂ O ₃ remains as a residue on the spray coating or in the pinholes, forming a thin chromium oxide ceramic coating layer on the surface of the spray coating of the roll. To be done. The thickness of the chromium oxide ceramic coating layer is
Since it is usually only a few μm, the chemical densification treatment may be carried out after adjusting the roughness of the surface of the sprayed coating in some cases.

[0018]

EXAMPLES The details of the roll in the molten metal plating bath of the present invention will be described below with reference to FIGS. 1 is a partial cross-sectional view of a roll in a molten metal plating bath of the present invention, FIG. 2 is a side view of a bearing portion of the roll in a molten metal plating bath of FIG. 1, and FIG. FIG. 4 is a partial cross-sectional view of one example, and FIG. 4 is a partial cross-sectional view of another example of the roll in the molten metal plating bath of the present invention.

Example 1 In FIG. 1, 1 is a solid support roll made of a heat-resistant material of martensitic stainless steel, and 2 is a WC formed on the surface of the solid support roll 1 with a thickness of 50 to 150 μm.
The surface of the sprayed coating 2 is a sprayed coating of -12% Co. After spraying the surface of the sprayed coating with a grindstone or the like,
Ra3 by dull processing by alumina grit projection
Dull 3 having a roughness of 5 μm was formed. For the roll shaft 4 of the solid support roll 1, CrC having excellent corrosion resistance and wear resistance is used.
The material of the system is built up 5.

As shown in FIG. 2, the roll in the molten metal plating bath is fitted with wear-resistant bearing members 11 and 12 on the contact wear surface with the roll shaft 4 of the bearing, which is obliquely divided into two parts. The collars 14 at both ends of 13 are fitted to both sides of the roll frame 15 and inserted into the notches 16. Then, after setting the roll shaft 4, the locking claw 18 provided at one end of the upper bearing metal 17 is fitted into the engaging groove 19 of the lower bearing metal 13 and placed.
The upper and lower bearing metals 13, 17 were sandwiched between the bearing metal retainer 20 and the roll frame 15 and supported in the plating bath of the actual hot dip galvanizing line. Then, it was continuously used in a non-driving state for about one month. As a result, during the use period, there is no occurrence of defective rotation of the support roll,
Moreover, there was no problem in the surface quality of the plated steel strip.

Example 2 In FIG. 3, 1 is a solid support roll made of a heat-resistant material of martensitic stainless steel, 2 is a WC formed on the surface of the solid support roll 1 with a thickness of 50 to 150 μm.
The surface of the sprayed coating 2 is a sprayed coating of -12% Co. After the surface of the sprayed coating is sprayed, the surface of the sprayed coating is adjusted with a grindstone or the like.
After forming the ceramic coating layer 6 of chromium oxide to a thickness of several μm by the chemical densification treatment, the dull 7 having a roughness Ra of 3 to 5 μm was formed by dull processing by alumina grit projection as described above. On the roll shaft 4 of the solid support roll 1, a CrC-based material having excellent corrosion resistance and wear resistance is overlaid 5. The roll in the hot-dip galvanizing bath was supported in the hot-dip galvanizing line of an actual machine in the galvanizing bath in the same manner as in Example 1. Then, it was continuously used in the same non-driving state for about 22 days. As a result, during the period of use, there was no occurrence of defective rotation of the support roll, and there was no problem with the surface quality of the plated steel strip.

Example 3 In FIG. 4, 1 is a solid support roll made of a heat-resistant material of martensitic stainless steel, and 2 is 50 to 150 on the surface of the solid support roll 1 using a high-speed gas flame spraying method.
A WC-12% Co spray coating formed with a thickness of μ, the surface of the spray coating 2 is Ra3-5 μm by dull processing by alumina grit projection after the surface of the spray coating is adjusted by polishing with a grindstone or the like. Dull 3 having a roughness of 1 was formed. Then, a ceramic coating layer 6 of chromium oxide having a thickness of several μm was formed by the chemical densification treatment. The roll shaft 4 of the solid support roll 1 has corrosion resistance,
A CrC-based material having excellent wear resistance is overlaid 5.
The roll in the hot-dip galvanizing bath was fixed in the hot-dip galvanizing line of the actual machine in the same manner as in Example 1. Then, similarly, continuous use was performed in a non-driving state. As a result, there was no rotation failure of the support roll, and there was no problem with the surface quality of the plated steel strip.

[0023]

As described above, the roll in the molten metal plating bath of the present invention improves the frictional force between the roll and the plated steel strip due to the formation of the roughness on the roll surface, and the roll in the bath is not driven. Even when used in a state, it is possible to prevent defective rotation of the in-bath roll and defective surface quality of the plated steel strip such as scratches and chatter marks resulting from this, thus improving product yield.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a roll in a plating bath of the present invention in Example 1.

FIG. 2 is a side view of a bearing portion of a roll in a plating bath in Example 1.

FIG. 3 is a partial cross-sectional view of a roll in a molten metal plating bath according to the present invention in Example 2.

FIG. 4 is a partial cross-sectional view of a roll in a molten metal plating bath of the present invention in Example 3.

FIG. 5 is a schematic diagram showing an outline of a general continuous hot-dip metal plating line.

FIG. 6 is a schematic explanatory view of a drive type support roll.

FIG. 7 is a side view of a bearing portion of a conventional support roll.

FIG. 8 is a side view of a bearing portion of a conventional support roll.

FIG. 9 is a side view of a bearing portion of a conventional support roll.

[Explanation of symbols]

 1 Solid Roll 2 Thermal Spray Coating 3,7 Dull 4,34 Roll Shaft 5 Overlay 6 Ceramic Coating Layer 11,12 Bearing Member 13 Lower Bearing Gold 14 Tsuba 15,35 Roll Frame 16 Notch 17 Upper Bearing Metal 18 Locking Claw 19 Engagement groove 20 Bearing metal retainer 21 Steel strip 22 Snout 23 Molten metal tank 24 Sink roll 25 Plated metal 26, 27 Support roll 28 Wiping nozzle 29 Top roll 30 Drive motor 31 Reduction gear 32 Joint 33 Drive shaft 36, 37, 38, 39, 40 Bearing gold 41 Roll shaft retainer

Claims (4)

[Claims] 1. A steel roll is used as a support roll in a plating bath that rotates in contact with a plated steel strip in a molten metal plating bath, and a ceramic coating containing oxide or carbide as a main component on the surface of the steel roll. In the roll in the hot-dip galvanized metal plating bath, Ra 1.0 is applied to the surface of the sprayed coating of the roll in the bath.
A roll in a molten metal plating bath, characterized in that a dull having a roughness of -30 μm is formed. 2. A steel roll is used as a support roll in a plating bath which rotates in contact with a plated steel strip in a molten metal plating bath, and a ceramic coating containing oxide or carbide as a main component on the surface of the steel roll. In a roll in a hot-dipped metal plating bath, the chemical densification treatment film consisting of a chromium oxide ceramics coating layer is formed on the surface of the thermal spray coating of the in-bath roll, and Ra1.
A roll in a molten metal plating bath, characterized in that a dull having a roughness of 0 to 30 μm is formed. 3. A steel roll is used as a support roll in the plating bath which rotates in contact with a plated steel strip in a molten metal plating bath, and a ceramic coating containing oxide or carbide as a main component on the surface of the steel roll. In the roll in the hot-dip plating bath, the surface of the sprayed film on the roll in the bath has Ra 1.0.
A roll in a molten metal plating bath, characterized in that after a dull having a roughness of -30 μm is formed, a chemical densification treatment film consisting of a chromium oxide ceramics coating layer is formed. 4. A heat-resistant and abrasion-resistant metal is sprayed or overlaid on the roll neck portion of the roll in the molten metal plating bath,
The roll in the molten metal plating bath according to claim 1, wherein the bearing of the roll is made of ceramics.