JP3087011B2 - Sink roll for hot-dip metal plating bath - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the in the molten metal bath dip roll in the molten metal plating apparatus and the like of the steel strip
The present invention relates to a sink roll for reversing a traveling direction of a traveling strip when plating a steel strip.

[0002]

2. Description of the Related Art Conventionally, in hot-dip galvanizing, hot-dip aluminum plating, and hot-dip zinc-aluminum alloy plating bath apparatuses, the direction rolling roll of a running strip in the bath is called a sink roll. In order to perform uniform plating on the steel strip, it is required that the rotation of the sink roll be uniform. In order to meet this demand, a cross-groove-shaped groove is provided on the outer peripheral surface of the sink roll (Japanese Patent Laid-Open No.
No. 79356) and providing a large number of spiral grooves in the roll width direction (Japanese Patent Laid-Open No. 2-228458) has been proposed.

[0003]

However, in these rolls, the optimum conditions are not always grasped, and slip between a steel strip and a sink roll or transfer of a roll groove pattern called a sink roll mark to a plated steel strip is not performed. Had occurred.

[0004] In the prior art, the effect of reducing the adhesion of foreign matter in the plating bath, which easily adheres to the surface of the plated steel strip, can be expected by providing grooves regularly on the surface of the sink roll. The problem of slip phenomenon due to the adhesion of the alloy layer to the periphery and generation of sink roll marks due to changes in plating bath conditions have not been solved. The present invention solves the above-mentioned conventional problems, and provides a hot-dip galvanizing bath, a hot-dip aluminum plating bath, and a roll for a hot-dip metal plating bath that does not generate a sink roll mark on a steel strip plating surface in a hot-dip zinc-aluminum alloy plating bath. It is intended to provide.

[0005]

In order to achieve the above object, the present inventors have improved the operating conditions such as the running speed of the steel strip, the tension of the steel strip, and the shape of the groove formed on the outer peripheral surface of the sink roll. As a result of repeated studies to eliminate slips and sink roll marks, it was found that sink grooves could be eliminated by eliminating grooves engraved on the outer surface of the sink roll. As a result, it has been found that the running speed of the steel strip and the surface roughness of the outer peripheral surface of the roll have a close relationship with respect to the occurrence of slip, and the present invention has been completed.

That is, according to the present invention based on the above findings, the roll outer peripheral surface in contact with the steel strip is only an irregular rough surface, and the roughness is Rmax. Exceeding 150 μm, Rmax. The gist of the present invention is a sink roll for a hot-dip metal plating bath, wherein the thickness is less than 500 μm. The gist of the present invention is also a sink roll for a hot- dip metal plating bath provided with a coating layer of boride, carbide or oxide or a cermet material thereof on a part or the whole of the outer peripheral surface of the roll together with the rough surface condition .

[0007]

The structure and operation of the present invention will be described. Cross-groove-shaped grooves on the outer peripheral surface of the sink roll described above (Japanese Patent Laid-Open No.
79356) or a large number of spiral grooves in the roll width direction (Japanese Patent Laid-Open No. 228458/1990), no sink roll mark is generated on the steel strip even if plating is performed.

However, the running speed of the steel strip is 40 m /
min. Is exceeded, a slip occurs between the steel strip and the sink roll. When the groove is cut, the running speed of the steel strip is 100 m / min. Although no slip occurred, it was found that sink roll marks were generated on the plated surface depending on the steel strip tension and the plating bath conditions.

Therefore, in the present invention, the surface roughness Rmax. Is made only the rough surface larger than the size of the foreign matter in the plating bath, so that the running speed of the steel strip is 100 m / mi.
n. However, it was confirmed that no slip occurred and a plated surface without sink roll marks could be obtained.

[0010] That is, the present invention molten metal plating bath Shin
Crawl is the roll outer surface only without rough surface of the groove, its roughness Rmax. Over 150 μm, Rma
x. It is necessary that it be less than 500 μm. Any of cutting processing, rolling processing, electric discharge processing, grid blast processing or a combination thereof can be applied to the rough surface formation.

When the sink roll comes into contact with the steel strip in the hot-dip metal plating bath, the molten metal is interposed at the contact surface between the outer peripheral surface of the roll and the steel strip. Slip occurs depending on the tension condition. The grooves on the outer peripheral surface of the sink roll disclosed in JP-A-64-79356 and JP-A-2-228454 have a difference in running speed of the steel strip that does not slip when compared with the case where they are not cut. It is believed that it acts as a path for discharging the molten metal interposed between the sink roll and the strip. It is also conceivable that the groove causes a difference in surface pressure and a difference in bath component between a contact portion and a non-contact portion between the sink roll and the steel strip, and acts as a cause of the generation of a sink roll mark.

Therefore, in order to analyze the action of the groove on the outer peripheral surface of the sink roll, various experiments were performed to reproduce slip and the occurrence of a sink roll mark by changing the groove sectional area and the ratio of the groove to the contact surface. As a result, the groove cross section contributes to slip,
It has been found that by increasing the cross-sectional area, an effect on slip is obtained by acting as a path for discharging the intervening molten metal. Also, it was found that the ratio of the groove to the contact surface contributes to the generation of the sink roll mark, and that the ratio of 1: 1 acts as the surface pressure dispersion and the bath component difference dispersion, thereby obtaining an effect on the sink roll mark. did.

However, an object of the present invention is to eliminate a slip or a sink roll mark in a sink roll, and does not seek a solution for only one of them. To seek both solutions, the relationship between the groove and the contact surface is
Focusing on the relationship between the peaks and valleys in the sectional curve in the limit, the maximum depth Rmax. Using as an index, the outer peripheral surface of the sink roll in the hot-dip galvanizing bath was roughened to observe the occurrence of slip and sink roll marks.

Table 1 (Example of the present invention) and Table 2 (Comparative Example) show the surface roughness Rmax. And the relationship between the occurrence of slip during roll use and sink roll marks on the surface of the plated steel strip. In the example of the present invention, neither a slip nor a sink roll mark occurs, but in the comparative example, a slip occurs when the surface roughness is small, and when the surface roughness is large, the pattern is transferred to a state similar to the sink roll mark. It was confirmed that it became. As a result, Rmax. Exceeding 150 μm, Rmax. 50
It became clear that neither a slip nor a sink roll mark occurred in the sink roll whose surface roughness was adjusted to a range of less than 0 μm.

[0015]

[Table 1] * Remarks: No occurrence △: May occur ×: Always occur **: Grid blast processing

[0016]

[Table 2] * Remarks: No occurrence △: May occur ×: Always occur ―: Slip occurs at steel strip speed 100m / min., Evaluation not possible ***: Electric discharge machining

[0017]

EXAMPLES The present invention will be described specifically with reference to Examples.
This does not limit the invention. Example 1 Molten zinc with a diameter of 650 mm and a roll body length of 1500 mm
On the outer peripheral surface of the roll of the sink roll for the aluminum alloy plating bath, Rmax. 196 μm (see FIG. 1) was subjected to surface roughness adjusting rolling and used in a plating bath. As a result, the running speed of the steel strip was 100 m / min. It could be used without slip or sink roll mark.

Example 2 A surface roughness adjusting process was performed on a roll outer peripheral surface of a hot-dip galvanizing bath sink roll having a diameter of 650 mm and a roll body length of 1500 mm, and boric cermet was coated on its surface with a thickness of 60 μm.
Thermal spraying, and the final surface roughness is set to Rmax. 174 μm (see FIG. 2), as a result of use in a plating bath, a conventional groove was cut without generation of slip or sink roll mark, and a boride cermet was sprayed at 60 μm, and the final surface roughness was set to R.
max. Compared with a roll used at 50 μm (see FIG. 3), the life of the conventional product was extended to 70 days, which is three times more than the life of the conventional product.

[0019]

According to the present invention, as described above, it is possible to perform a stable plating process of a quality that does not generate a slip or a sink roll mark, and further to perform a boride, carbide or oxide or By forming these cermet material coating layers, the surface roughness change is suppressed,
The effect is that the roll life can be further extended,
It has great industrial value and is extremely useful in industry.

[Brief description of the drawings]

FIG. 1 is an enlarged explanatory view schematically showing a three-dimensional surface roughness profile roll-formed on a roll outer peripheral surface of a sink roll for a molten metal plating bath of the present invention.

FIG. 2 is an enlarged explanatory view schematically showing a three-dimensional surface roughness profile obtained by cutting and spraying the outer peripheral surface of a sink roll for a molten metal plating bath of the present invention.

FIG. 3 is an enlarged explanatory view schematically showing a three-dimensional surface roughness profile of a roll outer peripheral surface of a conventional plating bath sink roll.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tomio Kondo 4-5-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd. (56) References Japanese Utility Model No. 1-149458 (JP, U) JP-A-3-74654 (JP, U) JP-A-3-128656 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16C 13/00 C23C 2/00 C23C 4/00 C23C 4/10 C23C 30/00

Claims (2)

(57) [Claims] 1. An outer peripheral surface of a roll in contact with a steel strip is only an irregular rough surface, and its roughness is RmaX. 150μ
m, RmaX. A sink roll for a hot-dip metal plating bath having a thickness of less than 500 μm. 2. A hot-dip metal plating bath thin coating according to claim 1, wherein a coating layer of boride, carbide or oxide or a cermet material thereof is provided on a part or the whole of the outer peripheral surface of the roll.
Click roll.