JPH10235409A - Manufacture of metallic sheet excellent in gloss - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably improve the surface gloss of a material to be rolled by establishing a rolling method by which the generation of scratch and oil pit is suppressed in cold tandem rolling. SOLUTION: At the time of rolling a metallic sheet in a tandem mill train is which plural sets of rolling mills for cold-rolling the metallic sheet 1 with a pair of upper and lower work rolls 2A-2E are arranged, the work rolls of at least one stand, preferably the final stand are taken as cemented carbide rolls and, in the stand using the cemented carbide rolls, preferably the final stand, the axial center of the upper and lower work rolls are mutually crossed on a plane parallel to the face of the rolled sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, when cold rolling a metal plate with 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, Japanese Patent Laid-Open Publication No.
It is known that a cemented carbide roll such as a tungsten carbide (hereinafter, WC) alloy roll may be used as disclosed in JP-A-71603 and JP-A-8-39103.

For the same purpose, for example, Japanese Unexamined Patent Publication (Kokai) No. 4-71701 discloses that the axes of the upper and lower work rolls (the upper roll axis 20T and the lower roll axis 20) are arranged as shown in FIG.
It is disclosed that it is also effective to cross roll B) in a plane (corresponding to the paper surface) parallel to the rolled plate surface (corresponding to the paper surface) (hereinafter, WR cross rolling). Note that the bisecting angle between the upper roll axis 20T and the lower roll axis 20B is called a cross angle and is represented by θ. That is, in the WR cross rolling, rolling is performed in a state where the axis of the work roll is inclined vertically and inversely by the cross angle θ with respect to the axis position in the normal rolling (parallel rolling).

[0004]

In the case where the WC alloy roll is cold rolled as a work roll, for example, when the roll is rolled on the final stand of a cold tandem rolling mill row using such a roll, the rolled material is not used. On the surface of the surface, a minute defect called a scratch due to the transfer of the work roll ground is generated. When such scratches are present on the sheet surface, even if annealing and temper rolling, which are post-processes of the cold rolling, are performed, the scratches remain, and the sheet surface gloss of the final product is obtained when a normal roll is used. There is a problem that is only slightly improved as compared with.

When WR cross rolling is performed at the last stand of a cold tandem rolling mill row, no scratch occurs, but a minute defect called an oil pit due to an oil film of rolling oil occurs. When oil pits are present, the surface gloss of the sheet after rolling is improved as compared with normal rolling, but there is a problem that the sheet surface gloss of the final product subjected to annealing and temper rolling is only slightly improved.

Therefore, the present invention solves the above-mentioned problems relating to the surface gloss of the sheet, establishes a rolling method capable of suppressing the occurrence of scratches and oil pits in cold tandem rolling, and reduces the surface gloss of the material to be rolled. The purpose is to significantly improve.

[0007]

SUMMARY OF THE INVENTION According to the present invention, 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 a tandem rolling mill array in which a plurality of sets of rolling mills are arranged. The work roll of the stand is a super hard roll, and at least the stand using the super hard roll is characterized by crossing the axes of the upper and lower work rolls mutually in a plane parallel to the rolled plate surface. It is a manufacturing method.

Further, the present invention provides a method for rolling a metal plate by a tandem rolling mill row 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. This is a method for manufacturing a metal plate having excellent gloss, characterized in that a carbide roll is used and at least at the final stand, axes of upper and lower work rolls are crossed with each other in a plane parallel to the rolled plate surface.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The glossiness of a steel sheet surface depends on the surface roughness. On the steel sheet surface after normal rolling, micro defects with a depth of about several tens of μm called oil pits and micro defects with a depth of about several μm caused by the transfer of grinding marks on the work roll called scratches. Exists.

[0010] When rolling is performed using a carbide roll as a work roll, the flatness of the roll due to the rolling load is smaller, the oil film inside the roll bite becomes thinner, and oil pits are reduced as compared with the case of rolling using a normal work roll. However, since the transfer of the roll grinding marks becomes remarkable and scratches increase, the margin for improving the gloss is small. Therefore, when a carbide roll is used, measures are taken to reduce the roughness of the roll, but this measure increases the risk of slippage.

On the other hand, in the WR cross rolling, the microdefects are reduced because the rolled edges are inclined with respect to the rolling direction so that the grounded edges move in the roll bite so as to smooth the steel sheet surface in the width direction. However, since oil pits are not sufficiently reduced, there is a limit in improving gloss. Also, W
In the R cross rolling, the wear of the grinding line progresses faster than in the normal rolling, and the frequency of replacing the rolls increases.

The inventors of the present invention have studied to solve these problems of the prior art and, as a result, have noticed that WC alloy rolls have almost no wear during rolling. By rolling the rolls, it is possible to prevent the occurrence of oil pits and scratches, greatly improving the gloss of the steel plate.In addition, the roll roughness can be made coarser so that slipping can be prevented, and the frequency of roll change It has been found that the frequency of replacement of WC alloy rolls when ordinary parallel rolling is performed may be equivalent.

As the WC cemented carbide, it is preferable to use an alloy mainly composed of WC and further containing cobalt, nickel, chromium, titanium and the like. The cross angle θ is 0
Preferably, the roll roughness is in the range of 0.05 to 1.5 μmRa. The cross angle has a great influence not only on the gloss but also on the plate shape. The optimum value of the roll roughness differs depending on the surface roughness of the steel sheet on the entrance side of each rolling stand. It is preferable to use a rough roll on the front side and a fine roll on the rear side.

[0014]

EXAMPLE A SUS430 (ferritic) stainless steel sheet having a material thickness of 4.0 mm was rolled to 2.0 mm by a cold rolling mill (tandem rolling mill row) having four stands and five stands shown in FIG. The present invention has been practiced and its effects have been confirmed. In FIG. 1, a material to be rolled (metal plate) 1 is rolled from left to right in the figure. Each rolling stand has a pair of work rolls 2A to 2E and a backup roll 3A to
3E, work rolls 2A to 2D are vertically arranged in parallel from the first stand to the fourth stand with rolls of a normal material (5% Cr forged steel, the same applies hereinafter),
In the fifth stand, the work rolls 2E can be arranged crosswise as shown. In FIG. 1, reference numerals 4A to 4E denote nozzles for injecting a rolling oil or an emulsion 5 thereof onto the material 1 to be rolled on the entrance side of each rolling stand.

[0015]

[Embodiment 1] Here, in the fifth stand, the material and the vertical arrangement of the work roll 2E are crossed by (a) WC alloy (WC-20Co cemented carbide, the same applies hereinafter) roll (roll roughness 0.2 μmRa). (Θ = 0.5 °, hereinafter the same) [corresponding to the embodiment of the present invention], (b) WC alloy roll (roll roughness 0.2 μmRa)
(C) WC alloy roll (roll roughness 0.08μmRa)
(D) Normal material roll (roll roughness 0.2 μmRa)
, Cloth (e) Normal material roll (roll roughness 0.2 μmRa
) Is changed to 5 types of parallel
After performing 0 coils, the surface gloss of the steel sheet after rolling, annealing, pickling, and temper rolling, the presence or absence of slip during rolling, and changes in roll surface roughness (center line average roughness) were examined.

The surface glossiness was measured according to JIS Z 8741 Glossiness Measurement Method 5 (GS20 °). FIG. 2 shows the result. The numbers 1 to 10 on the horizontal axis in FIG. 2 represent the degree of progress of rolling (time elapsed) in the number of rolling coils. First, FIG.
As shown in (A), by comparing the condition (e) and the condition (c), it can be seen that the gloss is improved by using the WC alloy roll. Also, by comparing the difference between conditions (d) and (e) and the difference between conditions (a) and (b),
It can be seen that the use of a WC alloy roll significantly increases the degree of gloss improvement by WR cross rolling.

Further, from the comparison between the condition (b) and the condition (c), W
It can be seen that if the roughness of the C alloy roll is further reduced, the gloss is further improved. However, as shown in FIG. 2B, in that case, slip occurs frequently (2 to 4 in the condition (c)).
(Slip occurs at the 6th, 10th, and 10th strokes). Further, from FIG. 2 (C), when the WC alloy roll is used, the roll surface is hardly roughened even by WR cross rolling (condition (a)). It can be seen that a similar roll exchange frequency is sufficient.

[0018]

Embodiment 2 Similarly, in each of the first to fourth stands, the work roll is a tungsten carbide alloy (WC-20Co) roll and a cloth (roll roughness 0.2 μmR) is used.
a, a cross angle of 0.5 °), the above rolling was performed for 10 coils, and the surface gloss of the steel sheet after rolling, annealing, pickling, and temper rolling was investigated.
When a steel sheet of 450 to 500 points is obtained stably and crossed with a normal material roll at the final stand (Example 1 conditions)
It was found that the gloss was further improved as compared with (d)) and that the roll was hardly worn.

As described above, using the WC alloy roll, the WR
It can be seen that cross-rolling can improve all aspects of the steel sheet surface gloss, slip and roll wear. It goes without saying that the present invention is not limited to the range of the rolling mill, the steel type, and the sheet thickness according to this embodiment.

[0020]

According to the present invention, it is possible to produce a metal plate having an excellent surface gloss by cold rolling using a tandem rolling mill train.

[Brief description of the drawings]

FIG. 1 is a schematic view of a tandem rolling mill train in which the present invention is implemented.

FIG. 2 shows the effect of the present invention and shows conditions (a) to (e).
FIG. 4 is a graph showing changes with time in (A) glossiness, (B) presence or absence of slip, and (C) roll surface roughness with progress of rolling, shown for each case.

FIG. 3 is an explanatory diagram of WR cross rolling and a cross angle θ.

[Description of Signs] 1 Rolled material (metal plate) 2A to 2E Work roll 3A to 3E Backup roll 4A to 4E Nozzle 5 Rolling oil or emulsion 20T Upper roll axis 20B Lower roll axis

Continued on the front page (72) Inventor Kazuhito Kenmochi 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Pref. In Kawasaki Steel Research Laboratory (72) Inventor Masato Iri 1-Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Pref. (72) Inventor Hajime Nagai 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Chiba Works Chiba Works

Claims (2)

[Claims] When rolling a metal plate with a tandem rolling mill row 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, a work roll of at least one stand is replaced with a carbide roll. A method of manufacturing a metal plate having excellent gloss, wherein at least a stand using a carbide roll crosses the axes of upper and lower work rolls in a plane parallel to a rolled plate surface. 2. 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, at least the work roll of the final stand is made of a carbide roll. A method of manufacturing a metal plate having excellent gloss, wherein at least at the final stand, axes of upper and lower work rolls are crossed with each other in a plane parallel to a rolled plate surface.