JP3236553B2 - Roll for rolling metal sheet and rolling method using the roll - Google Patents

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 rolling a metal sheet (hereinafter simply referred to as "roll").
In particular, the present invention relates to a roll for rolling a metal sheet, which is suitable for improving the surface gloss of a metal sheet as-rolled or further subjected to post-treatment, applied to cold tandem rolling, and a rolling method using the same.

[0002]

2. Description of the Related Art Conventionally, in the cold rolling of a metal plate using a pair of upper and lower rolls, for example, the rolling of a stainless steel plate requiring the highest surface gloss, a small-diameter roll having a roll diameter of about 80 mmφ is provided. Using a cluster-type rolling mill, low-speed (about 10 cSt (about 40 ° C.)) mineral lubricating lubricating oil was neat-lubricated and performed at low speed. On the other hand, in recent years, in order to reduce the production cost, the improvement of the surface gloss has been directed even in tandem rolling using a large-diameter roll, which is generally inferior to the above-mentioned rolling method, in terms of surface gloss. Was. For example, Japanese Patent Application Laid-Open No. 8-267109 discloses that it is effective to perform rolling using a roll provided with a mesh-shaped roll abrasive grain that is inclined at substantially equal angles on both sides with respect to the roll axis. ing.

[0003]

However, in general, a polished stitch that forms a predetermined angle with respect to the above-mentioned axial center is substantially symmetrically machined on both sides with respect to the axial direction (or rolling direction), that is, symmetrically. However, there is a problem that the polishing is difficult regardless of the method for imparting the polishing grain, and the production is difficult. For example, if an attempt is made to apply polishing lines inclined at 45 ° to the rolling direction with an accuracy of ± 1 ° on both sides, the setting and adjustment of polishing conditions (abrasive material, roll diameter, roll rotation speed, grinding wheel rotation speed, etc.) must be performed. Although it is necessary to perform it delicately, it is not easy to keep it within the above range. Further, in the roll according to the above-described conventional technology, the effect of improving the gloss at the beginning of rolling is great,
Since the abrasion progresses much faster compared to the grinding line parallel to the normal rolling direction, the gloss decreases even with a small amount of rolling, and it is stable for a long time without replacing the roll with a glossy steel plate. There was also a problem that rolling was difficult.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and it is easy to manufacture industrially, and when used for cold tandem rolling of a metal plate, it is excellent. An object of the present invention is to provide a rolling roll capable of producing a rolled material having a surface gloss. Another object of the present invention is to provide a metal sheet rolling roll suitable for use in cold tandem rolling, which has low abrasion and can stably maintain excellent surface gloss after rolling for a long period of time. .

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have studied in detail the angle of the polishing line formed on the peripheral surface of the roll, particularly in relation to the material of the roll, and have achieved the present invention. It was completed. That is, the gist configuration of the present invention is as follows. (1) On the peripheral surface of the roll, abrasive grains parallel to each other, which are inclined at an angle of 0.5 to less than 90 ° on one side with respect to the circumferential direction (rolling direction) of the roll, and on the other side, 0-90 °
A roll for rolling a metal sheet, characterized in that polished stitches which are less than and inclined at an angle different from the above-mentioned angle and which are substantially parallel to each other are provided in a stitch shape. (2) The roll for rolling a metal sheet according to the above (1), wherein the roll material is a cemented carbide. (3) A composite roll in which the shaft center is steel and the outer layer is a cemented carbide sleeve having a Young's modulus of 35000 kgf / mm ² or more, wherein the thickness of the outer layer is 3% or more of the roll radius. The roll for rolling a metal sheet according to the above (1). (4) A rolling method characterized by rolling a metal plate using the roll according to any one of (1) to (3). (5) As the cemented carbide, Co, Ni, Cr,
A WC alloy to which Ti or the like is added is preferable.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below by taking the case of cold rolling of a steel sheet as an example, including the background of the inventors' idea of the present invention. Although the gloss of the steel sheet surface depends on the surface roughness, the surface of a normal rolled steel sheet is caused by micro defects having a depth of about several μm called oil pits and the transfer of polished eyes of the roll called scratches. There are micro defects with a depth of less than 1 μm. By the way, when low-speed rolling is performed by using a small-diameter mirror roll and low-viscosity neat oil by the cluster rolling mill described above, the roll surface is mirror-finished, so that scratches can be prevented. Therefore, since the bite angle is large, the lubricating oil has a low viscosity and the rolling speed is low, the oil film of the rolling oil drawn into the roll bite becomes thin. As a result, since the roll and the steel plate are sufficiently in contact with each other and the generation of oil pits is reduced, good surface gloss can be obtained.

On the other hand, in the case of tandem rolling,
Since the diameter of the roll is large, the rolling speed is high, and since high-viscosity rolling oil is used to prevent seizure (heat streak), the oil film of the rolling oil drawn into the roll bite becomes thick. As a result, a large number of oil pits are generated, and since the roll roughness cannot be reduced to prevent slipping, the scratch becomes deep. For these reasons, the surface of the steel sheet after general tandem rolling has large surface roughness and low surface gloss. In addition, since it is necessary to perform tandem rolling at high speed, it is difficult to change the roll diameter and the rolling oil in order to improve gloss.

Now, under the circumstances described above, the inventors have:
In order to improve the surface gloss of the tandem-rolled steel sheet, an attempt was made to change the polishing grain on the roll surface. On the surface of a normal rolling roll, there is a polishing grain substantially parallel to the rolling direction. During rolling, the relative slip direction between the steel sheet surface and the roll surface coincides with the direction of the polishing grain on the roll surface. The roll roughness is transferred to the roller, causing scratches. Therefore, the present inventors, when the abrasive grain is applied to the roll surface inclining with respect to the rolling direction, the shear deformation in the rolling direction near the surface in the roll bite increases, the steel sheet surface is smoothed, and the gloss is good. Was found.

According to the study by the inventors, micro-defects such as oil pits and scratches existing on the surface of a steel sheet are several μm in size, while relative slip in the rolling direction in a roll bite is tandem rolling. Several meters for large diameter rolls
m. Therefore, the inventors need not continuously apply polishing lines for smoothing micro defects of several μm, and even if intermittent, the relative slip distance becomes several hundred times or more. The roll of the present invention was conceived, considering that the gloss should be improved.

In the roll of the present invention, as shown in FIG.
The surface of the roll is inclined to one side with the circumferential direction of the roll (same as the rolling direction) interposed therebetween, and polished eyes parallel to each other,
A polished stitch that is inclined to the other side and parallel to each other intersects each other to form a stitch shape. At this time, it is necessary to form the polished eyes of the roll at a predetermined angle with respect to the circumferential direction, but both inclination angles sandwiching the circumferential direction in FIG.
It is not necessary to work (symmetrically) so that θ ₁ and θ ₂ are equal. As described above, when θ ₁ and θ ₂ are asymmetric, the productivity at the time of providing a polishing grain is remarkably improved.
Further, since these polishing stitches may be intermittent, it is not necessary to mirror-finish the roll surface before polishing, and the polishing stitches can be easily and efficiently applied.

In the case of a roll having such a polished surface on the surface, when the material of the roll is a normal steel (5% Cr forged steel), the gloss of the rolled material surface is reduced by rolling for a relatively short period of time. That was inevitable. This phenomenon is a schematic diagram of FIG. 2. From the initial state shown in FIG. 2 (a), as shown in FIG. 2 (b), the convex portion of the polishing eye is rapidly worn, and the polishing eye is stably maintained. Is described as becoming difficult. Therefore, the inventors also studied a roll material that can withstand abrasion. As a result, it was concluded that a roll employing a cemented carbide in the surface layer of the roll exhibited excellent results, and that the surface gloss of the rolled material could be stably maintained for a long period of time.

Next, the present invention will be described in detail with reference to the experimental results which are the basis of the present invention. A SUS 430 ferritic stainless steel having a material thickness of 4.0 mm was rolled to a thickness of 2.0 mm at a rolling speed (roll speed of the final stand) of 300 m / min by a cold rolling mill having a four-stage mill and five stands shown in FIG. In addition,
In FIG. 3, a metal plate 1 to be rolled is rolled from left to right in the figure. Each rolling stand has a pair of upper and lower rolls 2A to 2E and backup rolls 3A to 3E.
It consists of. In this rolling mill, the polishing stitches of the rolls of the fifth stand are angled with respect to the circumferential direction (θ ₁ and θ _{2 in} FIG. 1; these polishing stitches are inclined to both sides with respect to the circumferential direction). The roll material was changed to 5% Cr forged steel (Young's modulus: 21
000 kgf / mm ² ) or WC cemented carbide (Young's modulus 35000 kgf /
mm ² or more), the above rolling was performed for each of 30 coils, and annealing, pickling, and temper rolling were performed. In Table 1, the roll of condition A is a normal polishing roll, and the roll of condition B is
This is one in which a polished grain is provided by the conventional technique described in JP-A-8-267109. The rolls under the conditions C to F correspond to the present invention, and one or both of θ ₁ and θ ₂ are reduced.
The surface of the steel sheet obtained by rolling in this manner was examined for glossiness (JIS Z 8741 glossiness measurement method (GS 20 °)). The results are shown in FIG. 4 and FIG. In addition, regardless of the difference in the inclination angle of the polishing line, there was no problem such as meandering or seizure, and stable rolling was possible.

[0013]

[Table 1]

The following results were found from the obtained results. In other words, the angle of the stitches polished in a stitch shape does not have to be inclined at the same angle on both sides with respect to the circumferential direction, and one angle with respect to the circumferential direction is extremely slightly inclined with respect to the circumferential direction. What is necessary is that if one polishing line is inclined at a predetermined angle with respect to the circumferential direction, the condition is satisfied even if the angle of the other polishing line is 0 ° (the same as the circumferential direction). As shown in C, the scratch can be reduced and the gloss can be improved, and the gloss improving effect obtained by such a stitch-like polished stitch can be obtained even when the roll material is a conventional steel type. In this case, it can be sustained for a much longer period than steel-based ones.

The present inventors have studied in more detail the angle of the polished line inclined to both sides with respect to the circumferential direction forming the stitch, and as a result, the inclination angle of one polished line is 0.5 to 90.
It has been found that gloss improvement can be obtained when the angle is less than 5 °, preferably 5 to 85 ° from the viewpoint of easy polishing. This is because if the inclination angle is less than 0.5 °, the scratch is transferred and the gloss is not improved, and if it is 90 °, it becomes parallel to the axial direction and polishing becomes difficult. In addition, 5
~ 85 °, ± 5 ° for 10 ° (or 80 °) setting
And the polishing is facilitated.In addition, the inclination angle of the other polished eye may be any number of times within the range of 0 to less than 90 °, and in consideration of the ease of polished eye application, it is preferable. It is also found that the angle should be 0 to 85 °. Here, the angle is set to 0 ° or more because 0 ° is a normal circumferential direction and can be easily realized.

The inventors have also investigated the material of the roll in detail. FIG. 6 shows that the angle of the stitch-like
5 ° / 45 ° (Condition D in Table 1), the same rolling was performed with various changes in the Young's modulus of the roll material, and then annealing,
It is the result of measuring the glossiness of the steel sheet surface after pickling and temper rolling. From Fig. 6, the Young's modulus was set to 21000 kg for steel rolls.
The gloss gradually increases with f / mm ² , 25000 kgf / mm ² of zirconia (ZrO ₂ ), and 30000 kgf / mm ^{2 of} Sialon. Gloss increases remarkably when it exceeds 35000 kgf / mm ^{2 of} cemented carbide. It was found to improve. 35 cemented carbide Young's modulus
In order to increase the pressure to 000 kgf / mm ² or more, a WC (tungsten carbide) -based cemented carbide is preferable.
A WC-Co alloy added in a range of 50 wt% or less is preferable.

As described above, when a cemented carbide represented by a WC-Co alloy is applied to a work roll for cold rolling, the surface gloss of the steel sheet can be obtained even when the entire roll is made of a WC alloy. Although there is no problem, there is a problem that the production cost becomes extremely high when it is assumed to be used for a large-diameter roll for a tandem rolling mill. Therefore, the sleeve material is made of cemented carbide material and the core material is made of steel material.
If the surface layer of the roll is made of a cemented carbide by using a sleep type composite roll having a structure in which both are fitted, the above problem can be solved, which is extremely effective in reducing costs.

However, when such a composite roll is used for rolling, it is conceivable that the flatness of the roll during rolling is different from the case of an integral roll of a WC alloy. Since the gloss of the steel sheet surface after rolling is greatly related to the flat roll radius, when rolling using a composite roll, the flat radius does not greatly differ from the WC alloy integrated roll, and the production cost is also taken into consideration. Above, it is necessary to set the outer layer thickness appropriately.

From this point of view, the inventors of the present invention have found that, in a composite roll in which a WC cemented carbide having a Young's modulus of 35,000 kgf / mm ² or more is fitted as a sleeve to a steel-based core material, the inclination angle with respect to the circumferential direction of the roll is considered. Rolls with a 15 ° / 45 ° (Table 1 condition D) polished line and various thicknesses of the sleeve were prepared. Here, the Young's modulus of the WC sleeve is
Regardless of the wall thickness, all were set to 35000 kgf / mm ² . Using this roll, the same rolling as in the experiment of FIG. 5 was performed, and then the surface gloss of the steel sheet that had been annealed, pickled, and temper rolled was measured. FIG. 7 shows the result.

FIG. 7 shows that if the ratio t / r between the thickness t of the WC sleeve and the radius r of the roll is 3% or more, the difference in glossiness between the WC integrated roll and the WC integrated roll falls within 10%, and is comparable to the WC integrated roll. It shows that it is possible to obtain a sufficient gloss improving effect. Therefore, in the present invention, the thickness of the cemented carbide sleeve, which is the outer layer of the composite roll, is desirably 3% or more of the roll radius. Note that the upper limit of t / r may be appropriately set according to the margin of roll manufacturing cost. In addition, as a cemented carbide, WC is Co,
WC alloys with improved fracture toughness by adding Ni, Cr, Ti, etc. are preferred, and among them, WC alloys with 10 to 50 wt% of Co added
-Co alloys are more preferred.

As described above, on the circumferential surface of the roll, substantially parallel polished stitches inclined at an angle of 0.5 to less than 90 ° on one side with respect to the circumferential direction, and 0 to 0 on the other side. By providing, in a stitch shape, substantially parallel polished stitches that are less than 90 ° and inclined at an angle different from the above-mentioned angle, it is possible to improve the gloss of the metal plate. By making this roll material a cemented carbide, it is possible to obtain a stable surface gloss for a longer period of time. In particular, the shaft center is made of steel, and the outer layer is made of 3% or more of the roll radius, Young, By using a cemented carbide sleeve having a rate of 35,000 kgf / mm ² or more, it is possible to reduce the cost of the roll that provides such an effect. The effect is that scratches due to the relative slip of the polishing eyes are reduced, and that the polishing eyes are stitched, preventing the inclusion of rolling oil and reducing the number of oil bits, and that there is almost no wear on the polishing day. Brought by. According to the roll of the present invention, a great effect is brought about without causing a problem such as meandering.

It should be noted that the polished lines inclined at one side with respect to the circumferential direction at an angle within a predetermined range need only be substantially parallel and not necessarily all parallel. In such a case, the average inclination angle should satisfy the condition of the present invention. Furthermore, the polishing lines do not necessarily have to be continuous, but are preferably intermittent in terms of manufacturability. The polishing surface of the roll surface may be provided by any processing method such as polishing with a rotary grindstone or loose abrasive, grinding with a grinding tool, or etching.

[0023]

Embodiments will be described below with reference to embodiments. Example 1 A WC-Co alloy to which Co20 wt% was added, a Young's modulus was 35,000 kgf / mm ² , and a wall thickness was a fifth stand of a cold rolling mill comprising five stands of a four-stage mill shown in FIG. A sleeve having a radius of 3% of the roll radius is polished on the peripheral surface of the composite roll fitted to the steel core material at an inclination angle of 0.5 ° / 15 ° (condition E in Table 1) with respect to the circumferential direction on both the upper and lower sides by rotating grindstone processing. (Invention Example) and a roll of 5% Cr forged steel integrated with a mesh with polished stitches inclined 45 ° symmetrically to both sides with respect to the rolling direction by rotating whetstone processing. Applying a roll (conventional example) equipped with a material thickness of 4.0 mm
SUS 430 ferritic stainless steel, 2.0
The steel sheet was rolled to 100 mm by 100 mm, and the surface gloss of the steel sheet after annealing, pickling, and temper rolling was investigated.

As a result, in the prior art, the roll was changed every 20 coil rolling, and a total of 5 sets of rolls were required, and the average glossiness (Gs20 °) was 432 points. The difference in average gloss between the eye and the 20th coil was 100 points or more. On the other hand, in the case of the inventive roll, all 100 coils could be rolled by one set of rolls. The average gloss (Gs20 °) was a good value of 550 points, and the difference in average gloss between the first coil and the 100th coil was at most 30 points, and stable gloss was obtained.

Example 2 A WC-Co alloy containing 35 wt% of Co and a Young's modulus of 40,000 kgf / mm ² was added to the fifth stand of a cold rolling mill comprising five stands of a four-stage mill shown in FIG. A sleeve with a wall thickness of 3% of the roll radius is applied to the peripheral surface of a composite roll fitted to a steel core material, and the upper and lower inclined angles with respect to the circumferential direction are 30 ° / 60 ° (Table 1, Condition F) by rotating grindstone processing. The surface of a 5% Cr forged steel integrated roll is symmetrically inclined at 30 ° to both sides with respect to the rolling direction by a rotating grindstone on the surface of a roll (invention example) with a knitted stitch. Is applied to a roll with a mesh shape (conventional example), and the material thickness is 4.0 m
m SUS 304 austenitic stainless steel was rolled by 100 coils to 2.0 mm each, and annealed, pickled, temper rolled, and buffed (one pass). The surface gloss of the steel sheet thus obtained was investigated.

As a result, in the prior art, the rolls were changed every 18 coil rolling, and a total of 6 sets of rolls were required. In addition, the average gloss (Gs20 °) was 550 points. The difference in average gloss between the first coil and the 18th coil was 120 points or more. On the other hand, in the case of the inventive roll, all 100 coils can be rolled by one set of rolls, and the average gloss (Gs20 °) is
A good value of 700 points was obtained, and the difference in average gloss between the first coil and the 100th coil was 43 points, and stable gloss was obtained.

[0027]

As described above, according to the present invention,
Since the knitted polished stitches provided on the roll peripheral surface are asymmetric in the rolling direction, it is easy to manufacture, and it is possible to provide a roll that can be used for tandem rolling of a metal plate to manufacture a metal plate having excellent surface gloss. Further, according to the present invention, by providing a surface material of the roll with a cemented carbide, it is possible to provide a rolling roll capable of producing a metal plate having a stable surface gloss for a long time. In particular, if the shaft is made of steel and the outer layer is made of a cemented carbide sleeve and fitted as a composite roll, such effects can be achieved at low cost, contributing to a significant reduction in the manufacturing cost of metal plates. I do.

[Brief description of the drawings]

FIG. 1 is a diagram showing the arrangement of polished eyes on the roll peripheral surface of the roll of the present invention.

FIG. 2 is a schematic diagram for explaining a wear process of a polished eye processed on a roll peripheral surface.

FIG. 3 is a view showing a tandem rolling mill to which the roll of the present invention is applied.

FIG. 4 is a diagram showing a change with time in glossiness of a stainless steel sheet rolled with steel rolls having different polishing angles θ ₁ and θ ₂ .

FIG. 5 is a graph showing a change over time in glossiness of a stainless steel sheet rolled with WC alloy rolls having different inclination angles θ ₁ and θ ₂ of the polishing line.

FIG. 6 is a graph showing the relationship between the Young's modulus of a roll material and the glossiness of a stainless steel plate.

FIG. 7 is a graph showing a relationship between a sleeve thickness (t) of a composite roll / a roll radius roll (r) and a glossiness of a stainless steel plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolled material 2 Roll 3 Backup roll 4 Coolant nozzle 5 Coolant (rolling oil)

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI B21B 27/03 510 B21B 27/03 510 (72) Inventor Hajime Nagai 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Chiba Inside the steelworks (72) Inventor Yasumori Sunamori 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Corporation Chiba Works (56) References JP 8-267109 (JP, A) JP 11-239808 (JP, A) JP-A-10-249403 (JP, A) JP-A-8-243606 (JP, A) JP-A-11-197721 (JP, A) JP-A 9-129009 (JP, A) JP-A-9-76003 (JP, A) JP-A-5-253604 (JP, A) JP-A-7-265913 (JP, A) JP-A-2-169108 (JP, A) (58) Int.Cl. ⁷ , DB name) B21B 27/02 B21B 1/22 B21B 3/02 B2 1B 27/00 B21B 27/03 510

Claims (4)

(57) [Claims] 1. A roll having a circumferential surface inclined at an angle of 0.5 to less than 90 ° on one side with respect to a circumferential direction of the roll.
A roll for rolling a metal sheet, comprising: a plurality of substantially parallel polished stitches; and a substantially parallel polished stitch on the other side, which is inclined at an angle of less than 0 to 90 ° and different from the aforementioned angle. 2. The roll for rolling a metal sheet according to claim 1, wherein the roll material is a cemented carbide. 3. The shaft center is made of steel, and the outer layer has a Young's modulus of 35,000 kgf.
^{2. The} roll according to claim 1, wherein the outer layer has a thickness of 3% or more of a radius of the roll, which is a composite roll having a cemented carbide sleeve having a thickness of not less than / mm ² . 4. A rolling method, comprising rolling a metal plate using the roll according to claim 1.