JP2726593B2 - Manufacturing method of high gloss metal plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling method for performing cold rolling by a roll cross rolling method, and more particularly to a method for producing a metal sheet having excellent glossiness with high efficiency.

[0002]

2. Description of the Related Art In recent years, demands from customers for the quality of rolled sheets of various metals including stainless steel sheets (hereinafter referred to as "metal sheets") have become increasingly severe.
Of these, stainless steel sheets are often used as they are cold-rolled, so that those with high glossiness are particularly required.

[0003] The glossiness of a metal plate is mainly affected by the surface roughness of a material to be rolled before cold rolling and the amount of lubricating oil during rolling. If the surface roughness of the material to be rolled is large, or if the amount of the lubricating oil during rolling increases, the glossiness decreases.

[0004] The metal sheet before cold rolling is usually pickled to remove scale on the surface of the metal sheet generated by hot rolling. At this time, to increase the scale removal capacity,
Mechanical descaling such as blasting or grinding is often used together. As a result, the surface of the metal plate becomes extremely rough, and its irregularities become large. Therefore, in order to obtain a metal plate having a high glossiness, it is necessary to remove minute defects using a coil grinder and to smooth the unevenness on the surface of the metal plate and then to perform cold rolling.

[0005] In order to obtain a metal plate having a high gloss, cold rolling using a Sendzimir mill is generally performed. When rolling using a Sendzimir mill, the work roll diameter is small,
Since the rolling speed is low, the amount of lubricating oil introduced into the roll bite is reduced, and the gloss of the metal plate is improved. However, on the other hand, the cold rolling by the Sendzimir mill has a problem that the rolling pass is repeated by a reverse method and that the productivity is low due to a low rolling speed due to a small roll diameter.

[0006] Recently, as the demand for a metal plate having a high glossiness has increased, attempts have been made to efficiently perform production using a tandem rolling mill capable of high-speed rolling.

For example, Japanese Patent Application Laid-Open No. 61-49701 discloses 15
After performing cold rolling using a tandem rolling mill equipped with a large-diameter work roll of 0 mmφ or more, the surface is subjected to finish cold-rolling using a Sendzimir mill using a small-diameter roll of 100 mmφ or less as a work roll. A cold rolling method for obtaining a stainless steel sheet having few defects and excellent corrosion resistance is disclosed. Further, the above publication discloses that if the surface roughness of the material before cold rolling is reduced to 25 μm or less in maximum height (Rmax) and then rolling is performed using a tandem rolling mill and a Sendzimir mill in combination, the surface properties after cold rolling can be improved. It is also shown that the effect is great. However, this method requires two types of equipment, a tandem rolling mill and a Sendzimir mill, and furthermore, since the Sendzimir mill is used finally, there is a problem that the rolling speed is still limited and productivity is not improved.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a method of cold rolling using only a tandem rolling mill having high productivity without smoothing the surface irregularities of a metal plate after pickling using a coil grinder. An object of the present invention is to develop a technology capable of rolling a metal plate having excellent gloss comparable to a product rolled at a low speed by a Sendzimir mill, particularly a stainless steel sheet with high efficiency.

[0009]

SUMMARY OF THE INVENTION In the course of research for increasing the gloss of a metal plate, the present inventors have limited the surface roughness of the material to be rolled to a relatively small range, and then optimized the cross angle to obtain a roll. It has been found that by performing cold rolling by the cross rolling method, it is possible to obtain a metal plate having extremely excellent glossiness.

The gist of the present invention is the following rolling method.

A hot-rolled sheet having a center line average roughness (Ra) of 3.0 μm or less is subjected to cold rolling by a roll cross rolling method in which a cross angle is 0.3 ° or more, and a high gloss metal sheet is provided. Manufacturing method.

When cold rolling is performed by the roll cross rolling method in the method of the present invention, only the upper and lower work rolls may be crossed and rolled in a plane parallel to the rolling surface, or the upper and lower backup rolls and the work may be crossed. Rolls may be paired and rolled in a plane parallel to the rolling plane. The former rolling method in which only the work rolls intersect is called a "work roll cross rolling method", and the latter rolling method in which a backup roll and a work roll are paired and intersected is called a "pair cross rolling method". Hereinafter, these are collectively referred to as “roll cross rolling method”.

[0013]

According to the present invention, a tandem rolling mill, which is a high-speed rolling mill with high productivity, is used, and cold rolling is performed by a roll cross rolling method.

Hereinafter, cold rolling by the roll cross rolling method will be described first.

FIG. 1 is a plan view for explaining rolling by a roll cross rolling method.

As shown in FIG. 1, the upper work roll 1 and the lower work roll 2 are crossed at a cross angle θ in a plane parallel to the rolling surface, and the metal plate 3 is rolled in the rolling direction X. This is rolling by a roll cross rolling method. When rolled by this roll cross rolling method, the upper work roll 1
Is shifted by an angle θ with respect to the direction of the rolling speed Vs of the metal plate, so that a slip component force Fc ₁ is generated on the upper surface of the metal plate 3 in the direction of the plate width Y. Similarly, since the direction of the peripheral rotation speed of the lower work roll 2 is shifted by an angle θ with respect to the direction of the rolling speed of the metal plate,
A sliding component force Fc ₂ is generated on the lower surface in the plate width direction. This sliding component gives a shear deformation to the surface layer of the metal plate 3 in the width direction of the metal plate 3 to smooth the surface of the metal plate 3.

FIG. 2 is a diagram schematically showing a contact relationship between a work roll and a metal plate in a plate width direction.

As shown in FIG. 2, when rolling is performed by a roll cross rolling method, for example, the convex portion of the polished eye of the upper work roll 1 moves relatively to the metal plate 3 in the width direction Y of the metal plate.

This movement increases the metal contact between the upper work roll 1 and the metal plate 3 and causes the surface of the metal plate 3 to be ground, so that the surface of the metal plate 3 is further smoothed and the glossiness is increased. .

In order to effectively exert the effect of rolling by the roll cross rolling method as described above, the cross angle θ of the work roll was confirmed by experiments, and it was necessary to set the cross angle to 0.3 ° or more. It turned out to be. If the cross angle is less than 0.3 °, the smoothing effect due to the slip component and the grinding effect due to the movement of the convex portion of the polishing eye are weakened, and the effect of improving the glossiness of the metal plate is reduced.

Next, the surface roughness of the material to be rolled will be described.

In order to improve the glossiness of the metal plate, it is important to reduce the amount of lubricating oil introduced between the work roll and the metal plate and bring the work roll into direct contact with the metal plate. Normally, circumferential polishing lines remain on the surface of the work roll, and peaks and valleys are formed. During rolling, the peaks of the polishing line contact the metal plate, and the valleys of the polishing line are filled with the lubricating oil and are separated from the metal plate. On the other hand, if there is a large recess on the surface of the metal plate, the recess is filled with the lubricating oil. The lubricating oil present in the valleys of the polished eyes or the concave portions on the surface of the metal plate not only does not directly contact the work roll with the metal plate, but also causes minute defects called oil pits. That is, when the lubricating oil is sealed between the work roll and the metal plate, the surface of the metal plate in which the lubricating oil is sealed is not restrained by the work roll and is freely deformed. As a result, minute irregularities are generated on the surface of the metal plate due to the oil pressure of the contained lubricating oil. Such minute defects further reduce the gloss of the metal plate. Therefore, it is necessary to make the valleys of the polished eyes and the recesses on the surface of the metal plate as small as possible to reduce the amount of lubricating oil trapped therein. However, when the amount of the lubricating oil is insufficient and the rolling oil film breaks, seizure (heat scratch) occurs. As described above, since the lubricating oil trapped in the valleys of the polished eyes and the recesses on the surface of the metal plate has an important function of preventing seizure, the work roll that determines the amount of lubricating oil trapped is determined. It is extremely important to determine the surface roughness of each of the metal plate and the metal plate.

The size of the valleys of the polished eyes on the work roll surface is 0.2 mm as the center line average roughness (Ra) of the work roll surface.
The thickness is desirably about 0.5 μm, which can be obtained by a usual roll polishing method for polishing a work roll in a circumferential direction.

On the other hand, the size of the concave portion on the surface of the metal plate must be 3.0 μm or less in terms of the center line average roughness (Ra) of the surface of the metal plate. The center line average roughness (Ra) of the metal plate surface is 3.
If it is 0 μm or less, even under lubricating conditions in which oil pits are generated, by performing cold rolling by the roll cross rolling method in the method of the present invention, it is possible to obtain a metal plate having excellent glossiness. it can. If the center line average roughness (Ra) of the metal plate surface exceeds 3.0 μm, the effect of the rolling by the roll cross rolling method described above cannot be exerted, and it is difficult to improve the glossiness of the metal plate. . Therefore, the upper limit of the center line average roughness (Ra) of the surface of the metal plate to be rolled is set to 3.0 μm.

[0025]

EXAMPLES Table 1 shows rolling conditions when cold rolling was performed to confirm the effect of the method of the present invention.

Table 2 shows the gloss of the metal plate after cold rolling under each rolling condition.

First, the diameter is 550 mmφ and the surface roughness is Ra 0.
Using a 4Hi tandem rolling mill with three types of work rolls of 3 μm, diameter 400 mmφ, surface roughness Ra 0.4 μm and diameter 105 mmφ, surface roughness Ra 0.1 μm,
An annealed and pickled steel strip of ferritic stainless steel (SUS430) having a thickness of 1.0 mm was used as a test material and cold-rolled in only one pass by a pair-cross rolling method. At this time, the case where the surface of the steel strip is smoothed by the coil grinder,
The steel strip was classified into a case where the surface of the steel strip had been pickled without using a coil grinder, and the surface roughness of each steel strip was measured before rolling. Note that the cross angle θ is set to 0.0
The rolling speed is 450m / min,
Rolling was performed using an emulsion (viscosity 60 cSt, at 40 ° C.) having a particle diameter of 5 to 6 μm as a lubricating oil with a rolling reduction of 20%.

[0028]

[Table 1]

Next, the glossiness of the metal plate after cold rolling is
It was measured with a gloss meter at an incident angle of 45 ° specified in JIS. ◎ indicates that the gloss is 600 or more, ○ indicates that the gloss is 400 or more and less than 600, Δ indicates that the gloss is 200 or more and less than 400.
Those having a value of less than 00 are ranked in four stages as x marks, and are shown in Table 2.
Shows the measurement results.

[0030]

[Table 2]

Test Nos. 1 to 12 shown in Table 2 are examples of the present invention. That is, a rolled material having a center line average roughness (Ra) of 3.0 μm or less is subjected to cold rolling by a roll cross rolling method in which a cross angle is 0.3 ° or more. In addition, these rolled materials do not use coil grinders, the surface of the rolled material is pickled, and the roll diameter is 400 mmφ or more. Rolling. The glossiness of the metal plate after cold rolling is extremely excellent at 600 or more.

Test Nos. 13 to 23 shown in Table 2 are comparative examples. That is, the center line average roughness (Ra) of the rolled material is 3.0
μm or less, but cold rolling was performed by a method other than the roll cross rolling method (that is, a parallel roll rolling method). Among them, Test Nos. 13 to 18 were performed by rolling after smoothing the surface of the material to be rolled by a coil grinder, and the gloss of the metal plate after cold rolling was 600.
In particular, when cold rolling is performed using a large-diameter roll with a roll diameter of 400 mmφ or more, the gloss of the metal plate is 400
Was less than. In Test Nos. 19 to 23, the rolled material was rolled without pickling the surface of the material to be rolled without using a coil grinder, and the gloss of the metal plate was even lower. In particular, when cold rolling was performed using a large-diameter roll having a roll diameter of 400 mmφ or more, the glossiness of the metal plate was less than 200.

Test Nos. 24 to 26 shown in Table 2 are also comparative examples. That is, although the cold rolling is performed by a roll cross rolling method in which the cross angle is 0.3 ° or more, a rolled material having a center line average roughness (Ra) exceeding 3.0 μm is used. The glossiness of the metal sheet after cold rolling was less than 600, and the glossiness of the metal sheet decreased as the center line average roughness (Ra) of the material to be rolled increased.

When the cold rolling of the method of the present invention is performed, the surface of the material to be rolled is pickled and the roll diameter is 400 mmφ.
It can be seen that even if the above-mentioned large-diameter roll is used for rolling, a metal plate having extremely excellent gloss can be obtained.

The effect of the present invention does not depend on the type of rolling oil and the material of the material to be rolled. Incidentally, when the steel strip of austenitic stainless steel (SUS304) and the steel strip of low carbon steel were subjected to the cold rolling in the method of the present invention, a metal plate having extremely high gloss was obtained.

[0036]

According to the cold rolling of the method of the present invention, a metal sheet having extremely excellent gloss can be obtained even if the surface of the material to be rolled is rolled without pickling without being smoothed by a coil grinder. can get. In addition, since a tandem rolling mill provided with a large-diameter roll having a roll diameter of 400 mmφ or more is used, high-speed rolling is possible, and it is possible to efficiently produce a stainless steel sheet in which glossiness is particularly important.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating rolling by a roll cross rolling method.

FIG. 2 is a diagram schematically showing a contact relationship between a work roll and a metal plate in a plate width direction.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toru Kaneko 3 Kashima-cho, Kashima-gun, Ibaraki Prefecture, Kashima Works, Sumitomo Metal Industries Co., Ltd. No. 22 Mitsubishi Heavy Industries, Ltd.Hiroshima Works (72) Inventor Kanji Hayashi 4-6-22 Kanon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture 4-6-22 Shinmachi, Hiroshima Research Laboratory, Mitsubishi Heavy Industries, Ltd. (56) References JP-A-4-71701 (JP, A)

Claims (1)

(57) [Claims] 1. A hot rolled sheet having a center line average roughness (Ra) of 3.0 μm or less is subjected to cold rolling by a roll cross rolling method in which a cross angle is 0.3 ° or more, characterized by high glossiness. Manufacturing method of metal plate.