JPH0596309A - Roll for cold rolling and rolling method for metallic sheet - Google Patents

Abstract

PURPOSE:To provide a rolling roll for improving the surface gloss of metallic sheet that high-speed rolling is executed with large diameter roll and rolling method using the same. CONSTITUTION:(1) A roll for cold rolling with the diameter of >=150mm which has ground stripes parallel to the rotation axis of roll and arithmetic mean deviation of profile (Ratheta) in the circumferential direction is 0.10-0.60mum. (2) A cold rolling method for metallic sheet using the roll of the claim clause 1 (not reproduced) as a work roll in at lest the final pass in the case of rolling with a reverse mill or in at least the final stand in the case of rolling with a tandem mill. (3) This method is a method for cold rolling the metallic sheet with the reverse mill (or tandem mill) and a roll mentioned in the claim clause 1 having the Ratheta of roll of 0.25-0.60mum is used in a 1st pass (or 1st stand), a roll having the Ratheta of 0.1-0.4mum is used as a work roll in the final pass and, in the case the (1) roll is used as a work roll in a 2nd and succeeding passes, the Ratheta of that roll is set to 0.10-0.40mum and also the roll of which the Ratheta is smaller than that of a roll which is used in the 1st pass is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work roll for cold rolling having a special surface polishing state and a cold rolling method for a thin steel sheet having excellent surface properties using the work roll.

[0002]

2. Description of the Related Art Cold rolling of stainless steel sheets and the like, which emphasizes surface gloss, is usually carried out by a Sendzimir mill using a work roll of a small diameter of 100 mmφ or less. But,
In recent years, 150φmm capable of high-speed rolling with the aim of improving productivity
As described above, tandem mills for normal steel rolling using large-diameter work rolls and rolling with a levers mill have come to be performed. This is because, in these mills, rolls having a large diameter as described above are used as work rolls, and a water-soluble emulsion having a large cooling capacity is used as rolling oil, so high-speed rolling is possible and high productivity can be expected.

However, the metal sheet rolled by a rolling mill for ordinary steel is inferior in surface glossiness to that obtained by rolling by a Sendzimir mill. This is because an oil film is formed between the work roll and the material to be rolled when high speed rolling is performed with the large diameter work roll as described above, and at this time, the surface of the rolled material is freely deformed without being constrained and minute defects called oil pits are generated. Because it occurs.

Several proposals have been made to solve the problem of deterioration of the surface glossiness.
For example, Japanese Unexamined Patent Publication (Kokai) No. 2-92402 proposes a method in which the center line average roughness (Ra) of a work roll is reduced to 0.2 μm or less and the rolling oil concentration is set to 2% or less. However, in this method, the oil film thickness is extremely thin, and the local convex portions on the roll surface cause insufficient lubrication, causing seizure due to oil film breakage, and high-speed rolling cannot be performed. Further, Japanese Patent Application Laid-Open No. 60-227904 discloses a method of rolling in which the direction of the grinds present on the surface of the rolled material and the direction of the grinds on the surface of the work roll are crossed. This method is intended to eliminate oil pits by assuming that the surface of the rolled material has grinds in the longitudinal direction, and cutting the grinds with the grinds of the roll. Therefore, it cannot be applied to the rolling material surface without longitudinal grinding marks (defects), and it is inefficient to preliminarily make such grinding marks because the number of steps increases.

As described above, adjustment of the surface roughness of the work roll has been proposed so far in order to improve the surface gloss of the rolled metal plate, but it is still industrially effective and effective. There is no way. In addition, even if the glossiness can be improved to some extent as a whole product, in the ordinary rolling, the glossiness varies depending on the direction of the plate (the rolling direction and the direction perpendicular thereto). This problem is still unsolved.

Occurrence of oil pits due to excessive oil film, transfer of roll surface, seizure due to local lack of lubrication, slip due to insufficient work roll roughness, etc. are particularly noticeable when using a high-speed rolling machine with high productivity. Remarkably, the deterioration of the surface glossiness of the rolled product and the anisotropy of the glossiness reduce the commercial value and offset the high productivity.

[0007]

DISCLOSURE OF THE INVENTION The present invention has excellent surface properties (especially glossiness) comparable to those of products rolled at low speed with a Sendzimir mill even when using a high-speed rolling mill with high productivity.
The purpose was to develop a technology that enables highly efficient rolling of metal sheets with a stainless steel sheet, especially stainless steel sheets. To provide a rolling method.

[0008]

The gist of the present invention is the following roll (1) and the rolling methods (2) to (4) using the roll.

(1) It has polishing grains parallel to the rotation axis of the roll and has a center line average roughness (Raθ) of 0.10 in the roll circumferential direction.
Rolls for cold rolling of metal sheets with diameters of 150 mm or more that are ~ 0.60 μm.

(2) A cold rolling method for a metal sheet, wherein the roll of (1) above is used as a work roll in at least the final pass in the case of rolling with a lever mill and at least in the final stand in the case of rolling with a tandem mill.

(3) A method of cold rolling a metal sheet with a reversing mill, wherein in the first pass, the centerline average roughness (Raθ) in the circumferential direction of the roll is 0.25 to 0.60 μm. In the final pass, the roughness Raθ in the roll circumferential direction was 0.1 to 0.
When a roll of 4 μm is used as a work roll and the roll of (1) above is used as a work roll after the second pass, the center line average roughness (Raθ) in the circumferential direction of the roll is 0.10 to A cold rolling method characterized in that a roll having a size of 0.40 μm and a Raθ smaller than that of the roll used in the first pass is used.

(4) A method of cold rolling a metal sheet in a tandem mill, wherein the center line average roughness (Raθ) in the circumferential direction of the roll is 0.25 to 0.60 μm in the first stand. Roughness of the roll in the circumferential direction at the final stand Raθ
Use a roll of 0.1 to 0.4 μm as a work roll,
When the roll of (1) above is used as a work roll after the second stand, the center line average roughness (Raθ) in the circumferential direction of the roll is 0.10 to 0.40 μm, and the first stand A cold rolling method characterized in that a roll having Raθ smaller than that of a roll to be used is used.

When carrying out the rolling methods (2) to (4), it is desirable that the rolling reduction is 15% or more per pass in the levers mill and in one stand in the tandem mill.

[0014]

According to the present invention, many problems mentioned above are solved by adjusting the polishing pattern (roughness pattern) of the roll surface by devising the polishing state of the work roll having a diameter of 150 mm or more and capable of high speed rolling. It was born from the idea that it would be solved all at once.

The surface of the rolled material before cold rolling usually has a center line average roughness (hereinafter referred to as Ra) of about 2 to 3 μm. The lubricating oil trapped in the recesses of this roughness exerts hydrostatic pressure on the surface of the rolled material, the recesses do not disappear, and the work roll and the steel plate are separated by an oil film. At this time,
The surface of the rolled material is not constrained and is freely deformed, and new minute defects (oil pits) occur and the glossiness decreases. In order to reduce these minute defects, it is said that it is preferable to use a roll having a relatively large roughness and to increase the contact ratio between the roll and the surface of the rolled material for rolling. However, with this method, although the fine defects are reduced, the roughness of the roll is transferred to the surface and the glossiness is not improved.

FIG. 1 is a diagram for explaining the basic concept of the present invention. FIG. 1 (a) is a diagram for explaining the inclination (inclination angle α) of a polishing grain on the roll surface, and FIG. 1 (b) is for a normal roll surface. FIG. 3 is a diagram showing the direction of the polishing mesh, FIG. 6C is a diagram showing the direction of the polishing mesh of the roll of the present invention, and FIG.

As shown in (a), when the angle between the polishing eye and the circumferential direction of the roll (herein referred to as the tilt angle) is α,
In a normal roll, α is almost 0 as shown in (b). That is, the grind is in the roll circumferential direction (direction perpendicular to the axis). The polishing marks are transferred to the rolled material in a form extending in the longitudinal direction. The transfer of the roll roughness adversely affects the glossiness in the width direction of the rolled material, and when the glossiness of the surface is measured, the value measured in the longitudinal direction of the rolled material is higher than that in the width direction.

FIG. 1 (c) shows a roll of the present invention in which the polishing stitches are parallel to the roll axis direction. Hereinafter, this roll may be referred to as a "parallel polishing roll". Α in this case is almost 90
°. The gloss improving mechanism when such a roll is used will be described below.

FIG. 2 (a) shows the case of rolling with the normal roll shown in FIG. 1 (b). As shown in (d) of FIG. 1, when the rolled material S is rolled from the thickness t ₁ to the thickness t ₂ , at the point N (neutral point), the speed v of the rolled material and the roll peripheral speed V
Is the same as. Let v _{1 be} the rolling material speed at the point A on the rear side (roll entrance side, called the reverse area) and v ₂ be the rolling material speed at the point B on the front side (roll exit side, called the advanced area), v ₁ < V, v ₂ > V. Therefore, the movement of the roll surface on the surface of the rolled material, which is an abrasive grain, becomes A → N → B as shown in FIG. As long as the grinds are lined up in the rolling direction, the rolled material has slip flaws in addition to the transfer of the roll grinds, and both are overlapped and emphasized. When the transfer pattern of the roll surface roughness is viewed in a cross section in the width direction of the rolled material, the unevenness is sharp as shown in FIG. 2 (c). Moreover, as shown in FIG. 2 (d), when rolling with a normal roll, an oil film exists in the valley portion of the roughness in the width direction, and a new depression (small defect) is formed in the shaded portion of the corresponding steel plate surface. Occur.

FIG. 3 shows a state of rolling with the roll of the present invention. In this case, as shown in (b), the grinds perpendicular to the rolling direction move in the above A → N → B. The polishing marks transferred and left are near the exit side, and the polishing marks transferred on the input side and newly generated microdefects are crushed by the peaks of the adjacent polishing marks sliding on the surface of the rolled material. Will almost disappear. That is, in the shaded portion on the surface of the rolled material in (b), heat scratches, slip flaws, etc. generated on the surface during rolling in the previous pass or rolling in the previous stand in continuous rolling are also crushed and smoothed. Therefore, the unevenness in the plate width direction becomes gentle as shown in (c), and the gloss in the plate width direction is significantly improved.

FIG. 4 is a diagram schematically showing a state of relative sliding (change in positional relationship with time) between the roll and the rolled material. As shown in the figure, the contact point between the top of the roll roughness and the rolled material moves from (a) to (d) over time, and the amount of this movement, that is, the amount of slip corresponding to the length of the arrow in the figure, covers the entire width of the rolled material. The small defects are reduced and smoothed, and the surface of the steel sheet becomes less uneven as shown in FIG.

The above effect becomes more remarkable as the inclination angle α increases. The roll having the maximum α of 90 ° is the roll of the present invention, that is, the roll having the polishing grain parallel to the roll axial direction.

As described above, in the roll of the present invention, the polishing grain is parallel to the roll axis, and at the same time, Raθ in the roll circumferential direction is
Must be 0.10 to 0.60 μm. The action such as smoothing of the surface by the roll having the polishing eyes parallel to the roll axis is due to the grinding or crushing of the surface defects and the polishing eye transfer marks by the polishing eyes as described above. Raθ is 0.
If the thickness is less than 10 μm, the roughness is too small relative to the oil film thickness to cause many oil pits, and the peaks of the roll roughness do not reach the valleys of the oil pits, so the effects of grinding and crushing cannot be seen. On the other hand, when Raθ exceeds 0.60 μm, the rolled material sinks into the valley portion of the roll roughness, and a deep transfer mark is formed to make the roughness rough after rolling. In addition, local burning defects
(Heat scratch) and scratches caused by abrasion powder on the crests of the roll polishing also increase, and the effect of smoothing decreases.

Next, an example of the polishing method for producing the roll of the present invention will be described.

FIG. 6 shows a method of setting the roll and the grindstone for polishing, (a) is a side view,
(B) is a plan view. As shown in the drawing, the rotary shaft 4 of the cup-shaped or disc-shaped grindstone 3 having a radius r is tilted by ψ with respect to the normal line 5 of the roll and only one end is contacted, and the rotary shaft of the grindstone is moved by X with respect to the roll shaft. Install by offsetting.

Here, the roll rotation speed (V _R ) and the roll rotation direction component (V _T cos) of the grindstone rotation speed at the contact point P
If X and V _T are selected so that α) is equal to
By the velocity component indicated by V _X in the figure, polishing stitches parallel to the roll axis direction can be provided.

When cold rolling is performed using the roll of the present invention described above, this roll may be used as a work roll for all passes of rolling (all stands in the case of tandem mill). If the smoothing, beautification, and high gloss of the surface in the first half pass (the first pass in the case of a tandem mill) proceed, the action and effect in the second half pass or the second stand will be saturated, which is uneconomical. The rolling mill using the roll of the present invention as a work roll is 2
Hi or 4Hi mills and 6Hi mills, and levers type and tandem type rolling mills such as multi-stage cluster mills having 6 or more stages are not particularly limited to the types of rolling mills. Further, the roll of the present invention can be used not only as a work roll but also as an intermediate roll and a backup roll.

Next, a method of selecting an appropriate circumferential roughness of the roll when using the roll of the present invention having a polishing grain parallel to the axial direction for cold rolling, that is, the rolling method according to claims 3 and 4. Will be described.

When rolling a steel sheet, in order to effectively use the roll of the present invention, the top of the circumferential roughness of the roll must be in contact with the trough of the surface roughness of the steel sheet. Further, since the circumferential roughness of the roll is transferred to the steel plate surface, it is necessary to set an upper limit on the roughness and manage the roughness of the transferred steel plate surface.

The form of the surface roughness of the steel sheet in ordinary rolling changes as follows, as shown in FIG. That is,
In the initial pass, since the surface roughness of the steel sheet is large, the entire valley is not filled with the lubricating oil. AA 'in FIG. 5 (a)
The lines below the line BB ′ in FIG. 5 (b) are filled with oil, but since there is no oil above these lines, the ridges are quickly crushed. On the other hand, the portions below the lines AA 'and BB' are hardly crushed.

As shown in FIG. 5 (c), after the mid-pass when the surface roughness was such that all the surface irregularities were filled with lubricating oil, the lubricating oil exerted a hydrostatic effect on the surface of the steel sheet and the irregularities did not decrease. The roughness does not change significantly. That is, although there is a difference depending on the rolling conditions and the like, the surface of the steel sheet in rolling in multiple passes or in multiple stands has a relatively large roughness until the first one pass or after rolling in one stand and has two or two passes.
It can be said that it has a relatively small roughness after the stand, although there is some increase or decrease.

Considering the influence of the transfer of the roughness in the circumferential direction of the roll on the surface of the steel sheet, it is desirable that the roughness in the circumferential direction is the minimum necessary. Considering the material surface smoothing mechanism by the roll of the present invention, the necessary minimum roughness is the size in contact with the bottom of the steel plate surface roughness. From the above changes in the steel plate surface roughness, by using a roll with a large Raθ in one pass or one stunt with a large steel plate surface roughness and a roll with a small Raθ in two passes or two or more stands where the steel plate surface roughness is small. It is considered that rolling can be performed with few micro defects and with the transfer of Raθ to the steel plate surface suppressed as much as possible.

When rolling was performed using work rolls of various circumferential roughness based on the above consideration, the circumferential surface center line average roughness (Raθ) of the parallel polishing roll of the present invention was in the first pass or the first stand. At 0.25 to 0.60 μm
Range: 0.10 to 0.40 after the 2nd pass or the 2nd stand
When the roll roll Raθ used in the 1st pass or the 1st stand is larger than the Raθ roll of the work roll used in the subsequent pass or the stand in the μm range ... Improvement was achieved.

As shown in FIG. 5, the surface roughness of the steel sheet is generally large on the entry side of the initial pass, and the steel sheet surface roughness decreases as the number of rolling passes increases. By increasing the circumferential surface centerline average roughness (Raθ) of the roll surface in the initial pass so that the crests of the roll surface contact the troughs of the steel plate during rolling, the roll and the steel plate are relatively The slippage of the steel sheet suppresses the generation of microscopic defects on the surface of the steel sheet and improves the gloss. Since the unevenness is reduced in the first pass as described above, the roll roughness (Raθ) after the second pass is so small that the peaks of the roll surface come into contact with the valleys of the reduced steel plate.

As described above, the reduction of various defects (irregularities) on the surface of the rolled material is achieved by the relative slip between the work roll and the steel plate. The smaller the axial surface roughness of the work roll of the present invention is, the better. The work roll and the steel plate contact each other over substantially the entire width of the rolled material, and the defect reduction area is represented by the product of the width of the steel plate and the slip amount. In the conventional work roll, the unevenness of the surface roughness in the axial direction is steep,
Only the top of the steel sheet comes into contact with the surface of the rolled material, and microscopic defects occur on the surface of the steel sheet that does not come into contact with the top of the work roll roughness.

In the work roll of the present invention, as shown in FIG. 4 (d), if the amount of slippage between the work roll and the steel plate is equal to or larger than the ridge interval of the work roll surface circumferential direction roughness, the top of the work roll surface roughness is obtained. Comes into contact with the entire surface of the steel sheet, and most of the surface defects disappear.

The slip amount between the work roll and the rolled material is determined by the draft amount, the roll diameter, the neutral point position, the rolling load, etc., but simply changing the slip amount between the work roll and the steel sheet by the rolling reduction per pass When piled up, Re. ≧ 15% (However, Re. Is the rolling reduction per pass)
······························ It has been found that the surface defects are drastically reduced and the glossiness of the steel sheet surface is significantly improved.

Although the glossiness of the steel sheet is significantly improved by rolling satisfying the above-mentioned conditions (1) and (2), a cold-rolled metal sheet plate having an extremely high gloss can be obtained by satisfying the above conditions together. ..

Next, the present invention will be described more specifically with reference to Examples.

[0040]

[Example 1] As shown in Table 1, various metal plates having surface defects such as oil pits, heat scratches, slip flaws, etc. were put on a commercially available synthetic ester rolling oil (viscosity 60 cSt / 50 with a 2Hi rolling mill having a roll diameter of 380 mm). Cold rolling using the roll of the present invention under the conditions of a rolling reduction of 25% and a rolling speed of 400 m / min using a 3% emulsion of (.degree. C.), and measuring the surface condition and surface gloss after rolling at an incident angle of 20 °. It was measured with a reflection type gloss meter with an angle of 20 °. As a comparative example, a test was conducted in which a roll other than the roll of the present invention was used and rolling was performed under the same conditions.

Table 2 shows the rolling conditions and results of the examples of the present invention and the comparative examples.

According to rolling using the roll of the present invention,
It can be seen that the beautification of the metal surface after rolling progresses and the surface becomes highly glossy, and that effect has little to do with the material of the metal.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Embodiment 2] A backup roll driven 4Hi lever smill with a work roll diameter of 105 mm and a backup roll diameter of 330 mm was subjected to SUS4 under the conventional roll roughness conditions shown in Table 3.
30 steel, thickness 2.5mm, width 250mm, hot-rolled and annealed material (pickled) were rolled up to 4 passes according to the rolling schedule in Table 4, and then 5th pass under the roll roughness conditions shown in Table 5. Rolling was carried out. Rolling was carried out until the rolling length reached 10 km.

The rolling oil used in this case was a mineral oil-based rolling oil (viscosity 40 cSt / 40 ° C.) and was supplied neat (as it was) to the work rolls. The rolling speed was 100 m / min in each pass. The surface condition and surface gloss after rolling were measured in the same manner as in Example 1, and are also shown in Table 5. The surface gloss after four passes was 250 (Gs 20 °).

In the rolling method of the present invention, when the parallel polishing roll is used not only for the work roll but also for the back roll, it can be seen that the gloss after rolling shows a stable and high value for the longest time. ..

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

[Table 5]

[0051]

[Example 3] Table 6 in a 5-stand 4Hi tandem mill with a work roll diameter of 450 mm and a backup roll diameter of 1450 mm
SUS430 steel, thickness 2.5mm, width with pass schedule shown in
A 1000 mm hot rolled annealed material (pickled) was rolled. At that time, the rolls used in each stand are combined as shown in Table 7, and the rolling oil is a synthetic ester rolling oil (viscosity 60
cSt / 50 ° C) 3% emulsion.

The surface gloss after rolling is also shown in Table 7.

When the rolling method of the present invention is carried out in a tandem mill, it is found that it is most effective to carry out it in the final stand.

[0054]

[Table 6]

[0055]

[Table 7]

[0056]

[Example 4] A ferritic stainless steel was used with a two-stage rolling mill having a work roll with a diameter of 380 mm and a barrel length of 400 mm.
(SUS 430) hot rolled annealed material (thickness 3.2 mm, width 50 mm) (pickled) was used as a test material and cold rolled by levers rolling. Table 8 shows the rolling schedule. As the lubricating oil, a mineral oil-based rolling oil (used in neat) with a viscosity of 40 ° C and 90 cSt was used and rolled at a rolling speed of 20 m / min. Table 9 shows the surface roughness of the work rolls used and the inclination angle (α) described above. Corresponds to the roll of the present invention, and corresponds to the conventional roll. In this case, roll exchange was not performed until the end of all passes.

After each pass, the glossiness in the longitudinal direction and the widthwise direction of the steel plate surface was measured by a reflection type gloss meter having an incident angle of 20 ° and a measuring angle of 20 °. The results are shown graphically in FIG.

As shown in FIG. 7, when rolled using the roll of the present invention, the glossiness of the surface is dramatically improved in both the longitudinal and width directions of the steel sheet. Moreover,
There is almost no difference in glossiness in both directions.

[0059]

[Table 8]

[0060]

[Table 9]

[0061]

[Example 5] Using a six-stage lever smill with a work roll having a diameter of 380 mm and a barrel length of 1450 mm, the same ferritic stainless steel (SUS430) as in Example 4 with a thickness of 3.2 mm and a width of 1000 mm was annealed (pickled). Cold-rolling was carried out by reversal rolling using the finished material. The rolling oil used was a synthetic oil system of 45 cSt at 40 ° C, a 3% emulsion, and a particle size of 3.5 µm. As shown in Table 11, the surface roughness of work rolls is No. 2 and 3
The same for each pass (without roll exchange), No. 1 and 4
, 5 changed the roll and changed the surface roughness by the pass. The rolls used in Nos. 2 to 5 are the rolls of the present invention with α = 90 °, and the rolls used in No. 1 are normal rolls.

The rolling schedules for Nos. 1 to 4 in Table 11 are shown in Table 8 and No. 5 in Table 11 is used.
Was rolled according to the schedule shown in Table 10.

The glossiness of the steel sheet surface after each pass was measured in the same manner as in Example 4. The result is shown in FIG.

As is apparent from FIG. 8, by using the roll of the present invention and by appropriately selecting the circumferential roughness and the reduction rate per pass, the glossiness of the steel sheet surface is further improved. ..

[0065]

[Table 10]

[0066]

[Table 11]

[0067]

EFFECTS OF THE INVENTION When the roll of the present invention is used for rolling, particularly by the above-mentioned method of the present invention, the occurrence of minute defects on the surface of a metal plate, which is a problem in high-speed rolling using a large-diameter roll,
The surface gloss of the product is lowered due to the transfer of the roll surface, and the difference in the surface gloss depending on the measuring direction is significantly reduced, and a metal plate having a high gloss and excellent surface properties can be rolled with high efficiency.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the basic principle of the present invention,
(A) is a figure explaining the inclination angle (alpha) of the grinding | polishing eyes of the roll surface,
(B) is a figure which shows the grinding | polishing mark of a normal roll, (c) is a figure which shows the grinding | polishing mark of the roll of this invention, (d) is a figure which shows the relationship between the roll at the time of rolling, and a rolling material.

FIG. 2 is a diagram for explaining rolling by a normal roll and a transfer mechanism of a roll polishing eye at that time.

FIG. 3 is a diagram for explaining rolling by a roll of the present invention and a transfer mechanism of a roll-polished grain at that time.

FIG. 4 is a diagram illustrating a gloss improving mechanism by relative sliding of a roll and a rolled material according to the present invention.

FIG. 5 is a diagram for explaining changes in a surface roughness form of a rolled material for each pass (stand).

FIG. 6 is a diagram showing an example of a polishing method for producing the roll of the present invention.

FIG. 7 is a diagram showing the surface glossiness for each measurement direction of stainless steel obtained by cold rolling using the roll of the present invention and a normal roll.

FIG. 8 is a diagram showing the average surface gloss when performing multi-pass rolling using rolls of the present invention having different surface roughness for each pass, as compared with the case of using a normal roll.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Ken Masui 4-53-3 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. (72) Inventor Yukihiko Matsudaira 2-12, Minatomachi, Joetsu City, Niigata Prefecture No. 1 inside Japan Naoetsu Works

Claims (5)

[Claims] 1. A center line average roughness (Raθ) in the circumferential direction of the roll is 0.10 to 0.60, which has polishing grains parallel to the rotation axis of the roll.
Rolls for cold rolling of metal sheets with a diameter of 150 mm or more, which is μm. 2. A cold rolling method for a metal sheet, wherein the roll according to claim 1 is used as a work roll in at least a final pass in the case of rolling with a levers mill and in at least a final stand in the case of rolling with a tandem mill. 3. A roll according to claim 1, which is a method of cold rolling a metal plate with a levers mill, wherein in the first pass, the centerline average roughness (Raθ) in the circumferential direction of the roll is 0.25 to 0.60 μm. In the final pass, the roughness Raθ in the roll circumferential direction was 0.1 to 0.
When a roll of 4 μm is used as a work roll and the roll according to claim 1 is used as a work roll after the second pass, the center line average roughness (Raθ) in the circumferential direction of the roll is 0.10 to A cold rolling method characterized in that a roll having a diameter of 0.40 μm and a Raθ smaller than that of the roll used in the first pass is used. 4. A roll according to claim 1, which is a method of cold rolling a metal plate in a tandem mill, wherein the center line average roughness (Raθ) of the roll in the first stand is 0.25 to 0.60 μm. On the final stand, the roughness Raθ in the roll circumferential direction is
Use a roll of 0.1-0.4 μm as a work roll,
When the roll according to claim 1 is used as a work roll after the other second stand, the center line average roughness (Raθ) in the circumferential direction of the roll is 0.10 to 0.40 μm, and moreover, in the first stand. A cold rolling method characterized in that a roll having a Raθ smaller than that of the roll used is used. 5. The cold rolling method according to claim 2, 3 or 4, wherein the rolling ratio is 15% or more per pass in the levers mill and per stand in the tandem mill.