JPH10249406A - Manufacture of metallic sheet excellent in gloss - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the occurrence of a scratch and wear of a roll, and to improve the gloss on the surface of a material to be rolled by using work roll made of a sintered hard alloy ground in the axial direction in at least one stand when rolling the metallic sheet in a tandem rolling mill train. SOLUTION: The material (metallic sheet) 1 is rolled while rolling mill lubricant for lubrication, cooling or its emulsion is supplied from nozzles 4A to 4E. The work rolls to be mounted on a fifth stand must be those made of a 12% WC-Co alloy ground in the axial direction. Consequently, the metallic sheet excellent in the gloss on the surface and in the endurance of its gloss level, can be efficiently and stably manufactured. For the sintered hard alloy as a roll material, the one obtained by adding cobalt, nickel, chrome, titanium, etc. to WC (tungsten carbide), is recommendable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a metal sheet having excellent gloss, and more particularly to a method for manufacturing a metal sheet having excellent gloss by cold tandem rolling.

[0002]

2. Description of the Related Art Conventionally, when cold rolling a metal plate by a pair of upper and lower work rolls, for example, to improve the surface gloss of a metal plate such as a stainless steel plate, JP-A-8-71603 and JP-A-8-39103. It is known that a cemented carbide roll such as a tungsten carbide (hereinafter referred to as WC) alloy roll may be used as disclosed in Japanese Patent Application Laid-Open Publication No. H10-163,036.

[0003] Similarly, for example, in Japanese Patent Application Laid-Open No. 5-96309, it is effective to perform rolling using a steel-based work roll (hereinafter referred to as an axial polishing roll) provided with a polishing grain in the axial direction of the roll. It is disclosed that there is.

[0004]

When cold rolling is performed using a cemented carbide roll as a work roll as described above, for example, when the roll is rolled on the final stand of a row of cold tandem rolling mills, a rolled material is obtained. Micro-defects called scratches are generated on the surface by the transfer of the work roll grinding marks. If such scratches are present on the sheet surface, even after annealing and temper rolling, which are post-processes of cold rolling, these scratches remain, and the sheet surface gloss of the final product uses a steel roll. There is a problem that it is slightly improved compared to the case.

[0005] When rolling is performed using a roll polished in the axial direction at the final stand of the cold tandem rolling mill row, the surface of the steel sheet is smoothed due to relative slip between the rolling roll and the surface of the material to be rolled. Although the gloss is improved, the surface roughness of the roll surface due to abrasion progresses very quickly, and there is a problem that the effect of improving the gloss is not maintained when rolling is continued.

The present invention has been made in view of the above-described problems relating to the surface gloss of a sheet, and in a method of manufacturing a metal sheet by cold tandem rolling, both generation of scratches and roll wear are reduced to reduce the surface gloss of a material to be rolled. The purpose is to significantly improve.

[0007]

SUMMARY OF THE INVENTION According to the present invention, at least one tandem rolling mill in which a plurality of sets of rolling mills for cold rolling a metal plate by a pair of upper and lower work rolls are arranged in tandem is used. This is a method for producing a metal plate having excellent gloss, wherein the work roll of the stand is a cemented carbide roll polished in the axial direction.

In the present invention, it is preferable that the stand using the work roll as a cemented carbide roll includes a final stand.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The glossiness of a metal plate surface depends on the surface roughness. Usually, micro defects with a depth of about several tens of μm called oil pits are formed on the surface of the metal plate after rolling.
There is a micro defect having a depth of about several μm, which is caused by the transfer of a grinding roll of a work roll called a scratch.

[0010] When the work roll is rolled using a cemented carbide roll, the roll flatness due to the rolling load is smaller, the oil film inside the roll bite becomes thinner, and the oil becomes thinner than when rolling is performed using a steel work roll. Although the number of pits is reduced, the transfer of the roll-grinding to the metal plate becomes remarkable and the number of scratches increases. on the other hand,
In rolling with a steel roll polished in the axial direction, the micro defects are reduced by the roll and the metal plate surface sliding relatively in the rolling direction in the roll bite and the roll grind smoothing the metal plate surface. However, abrasion of the roll grinding progresses much faster than the rolling using a roll polished in the normal circumferential direction, and if the rolling is continued, the gloss improvement effect is not maintained, so the roll replacement frequency has to be increased. Did not.

[0011] The inventors of the present invention have studied to solve these problems, and as a result, have found that the wear of the cemented carbide roll hardly progresses during the rolling operation. Then, the cemented carbide roll polished in the axial direction is used. An abrasion-promoting experiment was performed by using the same, and it was found that the cemented carbide roll polished in the axial direction hardly wears the grinding pit unlike the conventional steel roll polished in the axial direction.

Further, by the test rolling of the stainless steel sheet using the cemented carbide roll, the generation of oil pits and scratches can be effectively suppressed, and the steel sheet has a synergistic effect of improving the roll material and the polishing direction of the roll. The gloss of the roll is greatly improved, and the frequency of roll changes
The present invention was completed by finding that the frequency of replacement of a cemented carbide roll having grinding edges in the circumferential direction is equivalent to that of a conventional steel-based roll, and the frequency is significantly lower than that of a conventional steel roll.

In order to obtain such a gloss improving effect, it is necessary to use the cemented carbide roll having the above-mentioned axially ground grain as a work roll of at least one stand of a row of cold tandem rolling mills. . Then, the metal plate rolled by the cemented carbide roll should not be rolled by the conventional roll at the subsequent stand in order to maintain the surface properties there. The roll stand preferably includes the final stand.

[0014] In addition, the cemented carbide as a roll material,
What added cobalt, nickel, chromium, titanium, etc. to WC (tungsten carbide) is recommended.

[0015]

The following is a comparison between the conventional method and the invention method. A SUS304 (austenitic) stainless steel sheet having a material thickness of 4.0 mm was rolled to 2.0 mm in a cold tandem rolling mill row of four-stage mills and five stands shown in FIG. In FIG. 1, a material to be rolled (metal plate) 1 is rolled from left to right in the figure while supplying rolling oil or an emulsion thereof for lubrication and cooling from nozzles 4A to 4E. Each rolling stand has a pair of work rolls 2A to 2E and a backup roll 3A to
3E, the work rolls of the first to fourth stands are ordinary circumferentially polished steel rolls (5% chromium cast steel).

The work roll mounted on the fifth stand is
(A) Axial polished WC-Co12
% Alloy roll, (b) Cemented carbide (WC-12% Co alloy) roll polished in the circumferential direction, (c) Steel roll (5% chromium cast steel) polished in the axial direction, and (d) ) Circumferentially polished steel rolls, changing the four conditions, the above rolling is continuously performed 10 coils, rolling-annealing-pickling-temper rolling-buff polishing of the product surface The change in gloss was investigated. The gloss is measured in accordance with the JIS Z 8741 gloss measurement method (GS20
°).

FIG. 2 is a transition diagram of the glossiness according to the number of coil rolls under each condition. Conventional steel rolls
From a comparison between the condition (c) of using the axial polishing roll and the condition (d) of using the circumferential polishing roll, the condition (c) improves the glossiness immediately after the start of rolling, but reduces the wear of the grinding surface. It can be seen that the process proceeds remarkably quickly and the gloss immediately drops to the level of the condition (d). On the other hand, under the condition (a) using the cemented carbide roll of the embodiment, the condition (c) of the conventional example was used.
There is almost no decrease in gloss due to wear of grinding eyes like
In addition, as compared with the conditions (b) and (d), the gloss is good, and it can be seen that the level can be maintained even when the number of rolling coils increases.

As described above, according to the present invention, by rolling using a cemented carbide roll polished in the axial direction,
The surface gloss of the metal plate is significantly improved, and the improved gloss level is maintained, so that stable productivity is excellent. Also, in the same cold tandem rolling mill row, when the cemented carbide roll of the embodiment condition (a) is applied to each of the first to fourth stands, rolling-annealing-pickling-temper rolling-buffing is also performed. The change in the gloss of the product surface after polishing with the number of rolling coils was investigated.

FIG. 3 shows the results. In FIG. 3, #
1 to # 5 are data when applied to the first to fifth stands, respectively. # 5 is the same data as (a) in FIG. 2, and (d) is the same data as (d) in FIG. From FIG. 3, it can be seen that the higher the rank of the stand to which the cemented carbide roll is applied, the higher the effect of improving the glossiness. It goes without saying that the present invention is not limited to the range of the rolling mill, steel type, plate thickness and the like used in the examples.

[0020]

According to the present invention, it is possible to efficiently and stably produce a metal plate having much better surface gloss than the conventional one by cold tandem rolling.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a cold tandem rolling mill train suitable for carrying out the present invention.

FIG. 2 is a transition diagram of glossiness according to the number of rolling coils in Examples and Conventional Examples.

FIG. 3 is a graph showing a relationship between a change in glossiness and an order of a stand for applying an axially polished cemented carbide roll.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolled material (metal plate) 2A-2E Work roll 3A-3E Backup roll 4A-4E Nozzle 5 Rolling oil or its emulsion

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuhito Kenmochi 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel (72) Inventor Masato Iri 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Address: Kawasaki Steel Corporation Chiba Works (72) Inventor Hajime Nagai 1 Kawasaki-cho, Chuo-ku, Chiba-shi

Claims (2)

[Claims] When rolling a metal plate with a tandem rolling mill row in which a plurality of rolling mills for cold rolling a metal plate by a pair of upper and lower work rolls are arranged in tandem, the work rolls of at least one stand are axially moved. A method for producing a metal plate having excellent gloss, which is a polished cemented carbide roll. 2. The method according to claim 1, wherein the stand in which the work roll is a cemented carbide roll includes a final stand.