JP2001239308A - Roll for rolling and method of cold rolling metal plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely cold roll a steel plate of which the quality of the surface is regarded as important without decreasing the quality of the surface caused by convex portions existing on the surface of a work roll and generating seizure. SOLUTION: The roll for rolling is coated with a hard film comprising carbide and nitride at least on its roll surface which contacts a rolled material according to PVD method, having a dull working face wherein average roughness RA of a center line is 0.10-1.0 μm in the longitudinal direction and in the circumferential direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll for rolling and a method for cold rolling a metal sheet, and more specifically, to a stainless steel sheet which is required to have excellent surface quality such as uniform surface roughness and high glossiness. The present invention relates to a rolling roll suitable for rolling a metal plate such as a titanium alloy plate and an aluminum alloy plate, and a cold rolling method for the metal plate.

[0002]

2. Description of the Related Art In cold rolling of a metal plate such as a stainless steel plate, a titanium alloy plate, and an aluminum alloy plate in which surface quality such as surface roughness and surface gloss is important, for example,
Multi-pass rolling using a small-diameter work roll having a diameter of 150 mm or less, or tandem mill rolling is performed. These rolled work roll materials include iron and steel materials such as alloy tool steel (herein referred to as “die steel”) and high-speed steel (herein referred to as “high-speed steel”) whose surface hardness has been increased by heat treatment. Is used.

By the way, the metal plate before being rolled by these work rolls has a surface roughness of 1.0 μm or more, and a concave portion exists on the surface. For this reason, the lubricating oil trapped in these recesses during cold rolling exerts hydrostatic pressure between the metal plate and the work roll, causing the surface of the metal plate to freely deform and generating oil pits (micro defects). Lowers the surface gloss.

[0004] Therefore, before rolling, the surface of the work roll applied to the rough pass or the preceding stand is made to have a relatively large surface roughness with a center line average roughness Ra of about 1.0 μm by cylindrical grinding using a grindstone. By reducing the recesses and oil pits by increasing the contact ratio between the metal plate and the work roll, and rolling the work roll by adjusting the surface roughness of the work roll to a smaller size in the downstream stand, and then finishing the work or finishing stand The surface of the work roll applied for use has a center line average roughness Ra of 0.05μ.
A rolling method of obtaining a metal plate having a desired high glossiness by performing rolling with a mirror finished surface of m or less is employed. Note that the center line average roughness Ra is related to the roll body length direction, that is, the direction perpendicular to the rolling direction.

[0005]

By the way, the protrusions present on the surface of the work roll are not only in the roll body length direction but also in the roll circumferential direction due to the work roll being ground in the circumferential direction. Also, there is a rolling direction of the metal plate.

For this reason, even when the metal plate is rolled by the above-mentioned conventional rolling method, the concave portion present in the width direction of the metal plate is divided to some extent by the convex portion present in the roll body length direction. However, there is a limit to what can be done, so that a decrease in surface gloss cannot be sufficiently suppressed. Further, the effect of reducing the concave portions of the metal plate in the rolling direction is insufficient, and the surface gloss in the width direction of the metal plate cannot be particularly improved.

In order to improve the surface quality of the rolled metal plate, it is effective to reduce the thickness of the oil film existing at the interface between the metal plate and the work roll as much as possible to increase the transfer rate of the roll surface. It is. However, conventional work rolls made of a steel material such as die steel or high-speed steel are liable to adhere to a metal plate, resulting in frequent surface gloss defects and seizure defects, resulting in poor quality.

[0008] As a work roll that is hard to adhere to a metal plate,
Ceramic rolls and super hard rolls have been put to practical use.
However, since these work rolls are extremely difficult to grind, it is almost impossible to adjust the surface roughness to the aforementioned center line average roughness. In addition, since these work rolls are inherently fragile, there is a major problem in durability in terms of strength when used in rolling.

Furthermore, in recent years, the rolling speed has been increased in order to improve the productivity of metal sheets requiring a high surface gloss, and tandem mill rolling has been performed using a work roll having a diameter of 200 mm or more. Is being considered,
When such rolling is performed, poor gloss, seizure and the like are more likely to occur.

Here, an object of the present invention is to use a metal plate, such as a stainless steel plate, a titanium alloy plate, or an aluminum alloy plate, on which the surface quality such as surface roughness and surface gloss is important, for example. An object of the present invention is to provide a roll for rolling and a method for cold rolling a metal plate, which can surely perform cold rolling without deteriorating the surface quality or seizure caused by the convex portion.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have obtained the following new findings (i) to (iii) to complete the present invention. did.

(I) By making the surface of the work roll an isotropic dulling surface and improving the form of the surface roughness,
The concave portions existing on the surface of the metal plate before rolling can be effectively removed to such an extent that deterioration of the surface quality can be prevented.

(Ii) By forming a hard coating made of a material other than a steel material having a property of hardly adhering to a metal plate on at least the surface of the work roll in contact with the material to be rolled, seizure is effectively prevented. Can be prevented.

(Iii) By combining the above items (i) and (ii), a metal plate having both a uniform surface roughness and a high surface gloss and having a much higher surface quality than conventional ones can be obtained. It can be manufactured stably.

The present invention is a roll for rolling, in which at least the roll surface in contact with the material to be rolled is formed of a hard coating, and the center line average roughness Ra in each of the body length direction and the circumferential direction is 0.1 mm. It is a roll for rolling characterized by having a dulling surface of 10 to 1.0 μm.

In the present invention described above, the hard coating is exemplified by a powder sintered body such as a ceramic, a cemented carbide or a cermet, or a carbide, a nitride, an oxide or a composite compound thereof. . In this case,
It is desirable that the hard coating be formed by a PVD method or a CVD method.

According to another aspect of the present invention, at least the roll surface in contact with the material to be rolled is formed of a hard coating,
Rolling a metal plate using a rolling roll having a dulling surface whose center line average roughness Ra in each of the body length direction and the circumferential direction is 0.10 to 1.0 μm. This is a cold rolling method for a sheet.

In the present invention, it is exemplified that the material to be rolled is a metal plate, such as a stainless steel plate, a titanium alloy plate or an aluminum alloy plate, whose surface quality such as surface roughness and surface gloss is important. .

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a rolling roll and a method for cold rolling a metal plate according to the present invention will be described in detail.

First, the rolling roll according to the present invention will be described. The rolling roll according to the present invention has significant characteristics in two points: (1) material and (2) surface roughness. Hereinafter, these will be described.

(1) Material In the rolling roll according to the present invention, at least the surface of the roll in contact with the material to be rolled is made of a material other than a steel material having a property of hardly adhering to the material to be rolled. In the present invention,
By making the protrusions on the roll surface as evenly and evenly in contact with the surface of the metal plate as possible, poor surface gloss is prevented. However, if the roll surface in contact with the metal plate is made of a steel material such as die steel or high-speed steel, adhesion to the metal plate is likely to occur, resulting in poor gloss and seizure. Is reduced.

Therefore, in the present invention, at least the material constituting the roll surface that is in contact with the material to be rolled is limited to a hard sintered body material having a property of hardly adhering to a metal plate. Specifically, there are powder sintered bodies such as ceramics and cemented carbides, and those having a hard coating such as carbide or nitride formed thereon and surface-modified.

Further, it is desirable that these hard coatings are coated by a PVD method or a CVD method, because the adjustment of the roll surface roughness is easy and the durability in terms of strength is excellent. PVD method or CVD
The processing conditions of the method may be in accordance with well-known and ordinary conditions, and are not limited to specific conditions. For example, in the case of PVD, an ion plating method is preferable, and in the case of CVD, a plasma CVD method is preferable in terms of bonding strength.
Conditions for coating a film of N, TiCN, TiAlN, CrN or the like with an appropriate thickness of several to 10 μm are exemplified.

Examples of the composition of the hard coating thus formed include TiN, TiCN, TiAlN, CrN and the like.

In the present invention, it is sufficient that at least the roll surface in contact with the material to be rolled is made of a material other than the above-mentioned steel material having a property of hardly adhering to the material to be rolled. No limitation is required. That is,
The roll for rolling according to the present invention may be a composite roll in which the core material is made of a material different from the above-described hard coating, or an integrated roll in which the hard coating and the core material are integrally formed of the same material. Is also good. The composition of the core material of the composite roll is, for example, C: 1.0-2.0%, Si: 0.2-2.
0%, Mn: 0.2 to 2.0%, Cr: 3.0 to 20.0
%, Mo: 0.5 to 10.0%, V: 6.0% or less, Co:
10.0% or less, W: 10.0% or less.

(2) Surface Roughness The roll for rolling according to the present invention has a dulled surface whose center line average roughness Ra in the body length direction and the circumferential direction is 0.10 to 1.0 μm.

The surface roughness of the metal plate before cold rolling is 1 μm or more in center line average roughness Ra, and recesses having a depth of about several μm are scattered. In rolling in the rough pass of the cold rolling or in the former stand, digging and digging at the convex portion existing on the roll surface, that is, efficiently removing the concave portion on the surface of the metal plate by shearing action and suppressing the generation of oil pits That is. Therefore, if the protrusions on the roll surface are in a straight line in the roll circumferential direction (rolling direction) like a normal cylindrical grinding surface, it is not possible to effectively divide the recess present on the surface of the metal plate,
The fact that the protrusions present on the roll surface are isotropically distributed in the roll surface is effective for accurately removing the recesses present on the surface of the metal plate.

Therefore, in the present invention, the form of the roll surface roughness is defined as a dulling surface in which convex portions are isotropically dispersed at least in the body length direction and the circumferential direction. The dulling means may be a known and commonly used means, and is not limited to a specific means. For example, discharge dull processing and laser dull processing are exemplified.

On the other hand, if the center line average roughness Ra of the dulling surface exceeds 1.0 μm, the degree of transfer of the roll projections becomes too high, and conversely, the generation of depressions on the surface of the metal plate may increase. There is. Therefore, in the present invention, it is desirable to limit the center line average roughness Ra of the dulling surface to 1.0 μm or less.

On the other hand, when the rolling roll according to the present invention is applied to finish rolling, the center line average roughness Ra of the dulled surface is reduced.
If it is less than 0.10 μm, the surface of the metal plate is not sufficiently constrained by the roll projections, causing local free deformation, which may generate minute defects and lower the surface gloss instead. Therefore, in the present invention, it is desirable to limit the center line average roughness Ra of the dulled surface to 0.10 μm or more.

From such a viewpoint, the rolling roll according to the present invention may have a dulled surface having a center line average roughness Ra of 0.10 to 1.0 μm in the body length direction and the circumferential direction. desirable.

The rolling roll according to the present invention has the material and surface roughness described above. Next, a method for rolling a metal sheet according to the present invention will be described. In the present invention, the metal plate is cold-rolled using the above-described rolling roll according to the present invention.

The cold rolling conditions may be according to well-known and ordinary means, and are not limited to any particular means. For example, using a tandem mill, the center line average roughness Ra of the dulled surface is 1.
Rough rolling is performed using the rolling roll according to the present invention having a large surface roughness of about 0 μm, and rolling is sequentially performed using the rolling roll according to the present invention in which the center line average roughness Ra of the dulled surface is reduced. Finally, finish rolling is performed using a rolling roll according to the present invention having a small surface roughness of about 0.10 μm in the center line average roughness Ra of the dulling surface.

At the time of the rough rolling to the finish rolling, the surface of the rolling roll according to the present invention has a height that can effectively remove the concave portions existing on the surface of the metal plate. Since the convex portions are isotropically distributed, the concave portions on the surface of the metal plate can be efficiently removed, and generation of oil pits can be suppressed.

Further, in any of the rolling rolls according to the present invention, at least the surface of the roll in contact with the material to be rolled is made of a material other than a steel material having characteristics that are hardly adhered to the material to be rolled. No seizure occurs at the time.

Further, since the rolling rolls according to the present invention each have a sufficient strength, there is no problem regarding durability even in rolling use.

Therefore, according to the present invention, it is possible to manufacture a metal plate having high surface glossiness and uniform surface roughness and excellent surface quality by cold rolling.

For this reason, in recent years, in order to improve the productivity of a metal plate requiring a high surface gloss, it is necessary to increase the rolling speed or to perform tandem mill rolling using a work roll having a diameter of 200 mm or more. Etc. are also possible, and the productivity can be dramatically improved.

[0039]

EXAMPLE Surface-modified rolls adjusted to the surface roughness shown in Table 1 (conditions 1 to 3; TiN-coated rolls by PVD treatment)
And SUS3 (condition 4; first to third passes are die steel rolls, fourth and fifth passes are high-speed rolls).
The effect of the roll surface roughness on the surface glossiness of the material to be rolled was evaluated.

[0040]

[Table 1]

The composition of the hard coating of the surface-modified roll was TiN, and the composition of the core material was C: 1.5.
%, Si: 0.4%, Mn: 0.4%, Cr: 12.0%, M
o: 1.0% and V: 0.4%.

On the other hand, the composition of the steel roll is as described above for the die steel, and for the high-speed steel, C: 1.5%, Si: 0.3%,
Mn: 0.3%, Cr: 4.0%, Mo: 4.0%, V: 4.0%
3%, Co: 5.0%, W: 5.5%.

In this example, the surface-modified rolls (conditions 1 to 3) and the steel rolls (condition 4) shown in Table 1 each had a roll diameter of 80 mm and were formed by a 5-pass Sendzimir mill in five passes. Rolling. The thickness of the material to be rolled before rolling was 2.0 mm, and the thickness after the fifth pass was 1.0 mm. Mineral oil was used as lubricating oil.

Under condition 1, the rolling roll according to the present invention was applied to the first to fourth passes, and the roughness (low roughness) was out of the range of the present invention only in the fifth pass. In the condition 2, the rolling roll according to the present invention was applied to the second to fifth passes, and the first pass was out of the range of the present invention (high roughness). Conditions 3 and 4 are comparative examples in which the surface was adjusted by conventional cylindrical polishing.

The results of the measurement of the glossiness (indicated by GS60 degrees) after each pass are shown in the graph of FIG. In the first to fourth passes of the first condition of the present invention, a higher surface glossiness was obtained as compared with the other conditions, and in particular, a very high value of GS500 or more was obtained in the fourth pass.

However, in the fifth pass having a low roughness outside the range of the present invention, the gloss was conversely reduced.

Further, under the condition 2 in which the surface roughness of the first pass is out of the range of the present invention, the surface gloss obtained in the first pass was insufficient, so that the improvement of the gloss after the second pass was not achieved. Delayed (or limited). Further, the improvement margin was small from the viewpoint of the glossiness under the conditions 3 and 4 as the comparative examples. Further, under the condition 4 using a steel roll, adhesion of the rolled material to the roll surface occurred in the fifth pass, resulting in uneven gloss.

[0048]

As described above in detail, according to the present invention, it is possible to efficiently remove the concave portions existing on the surface of the metal plate, and to reduce the surface quality and the seizure caused by the convex portions of the work roll. The present invention provides a roll for rolling and a method for cold rolling a metal plate, which can surely and stably perform cold rolling without causing the problem.

The significance of the present invention having such an effect is extremely remarkable.

[Brief description of the drawings]

FIG. 1 is a graph collectively showing measurement results of surface glossiness after each pass.

Claims (5)

[Claims] 1. A roll for rolling in which at least a roll surface in contact with a material to be rolled is formed of a hard coating, and has a center line average roughness R in each of a body length direction and a circumferential direction.
a. A roll for rolls, characterized by having a dulled surface in which a is 0.10 to 1.0 μm. 2. The rolling according to claim 1, wherein the hard coating is made of a powdered sintered body such as a ceramic, a cemented carbide, a cermet, or a carbide, a nitride, an oxide, or a composite compound thereof. For roll. 3. The method according to claim 1, wherein the hard coating is a PVD method or a CVD method.
The roll for rolling according to claim 1 or 2, which is formed by a method. 4. The roll surface at least in contact with the material to be rolled is formed of a hard coating, and the center line average roughness Ra in each of the body length direction and the circumferential direction is 0.10 to 0.10.
A cold rolling method for a metal plate, wherein the metal plate is rolled using a rolling roll having a dulling surface of 1.0 μm. 5. The method according to claim 4, wherein the material to be rolled is a stainless steel plate, a titanium alloy plate or an aluminum alloy plate.