JP2658765B2 - Work roll for cold rolling, method for manufacturing the same, and method for rolling a metal plate using the work 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 (hereinafter, referred to as a roll) for producing a metal plate having a high gloss by cold rolling.
A roll) and a method for producing the same, and a method for cold rolling a metal plate using the roll.

[0002]

2. Description of the Related Art When a metal plate is rolled, flaws or irregularities on the surface of the roll are transferred to the surface of the metal plate. Therefore, it is necessary to grind the surface of the roll according to the surface quality required for the product. is there. Therefore, when a cold-rolled metal plate requires excellent gloss, the roll is polished with a high-counting grindstone and used for rolling. However, as the surface roughness of the roll is reduced, the time required for the polishing operation increases.

[0003] On the other hand, for steel materials whose required surface quality is not so severe, a water-soluble emulsion having a large cooling capacity is used as a rolling oil, and a tandem mill, which is a rolling mill for ordinary steel using a large-diameter roll of 180 mmφ or more, is used. High-speed rolling is performed by a reversing mill, but the thin steel sheet that is high-speed rolled by a normal steel mill having a large-diameter roll has a depression called an oil pit due to the oil pressure of an oil film generated between the roll and the steel sheet, and the glossiness is high. Therefore, this method cannot be applied to cold rolling of a thin steel sheet such as a stainless steel sheet which requires high glossiness. Therefore, the production of thin steel sheets with high glossiness is performed at a low speed by a multi-high rolling mill called a Sendzimir mill using a small-diameter roll of 100 mmφ or less.

[0004] The minute concave defects called the oil pits are formed by the hydrostatic pressure of the rolling oil trapped in the concave portions on the surface of the metal plate and the concave portions on the roll surface. Moreover,
At this time, if the oil film formed between the metal plate and the roll is thick, a concave portion on the metal plate before rolling also remains. Japanese Patent Application Laid-Open No. 60-227904 proposes a method of rolling by intersecting the direction of the grinding line existing on the steel sheet surface with the direction of the grinding line on the roll surface for the purpose of preventing the glossiness from being reduced by the oil pit. ing. However, if there is no flaw on the surface of the steel material, it is inefficient to newly form a grinding line because the number of steps increases.

Japanese Patent Publication No. 62-11922 discloses that cold rolling using a microscopically patterned rolling cylinder prevents seizure and is suitable for subsequent coating. Have been. However, in such a structure in which motifs are repeatedly formed, rolling oil or metal powder generated by abrasion of rolls is unlikely to flow, so that oil pits are formed and the cylinder surface is flattened due to clogging of concave portions.

In order to prevent the formation of oil pits by rolling and not to leave the original concave portions on the metal plate, the rolling reduction should be increased so that the roll and the metal plate are sufficiently in contact with each other. It is good to roll. However, such a method can prevent the remaining of the concave portion of the metal plate and the generation of oil pits, but the polished eyes of the roll are transferred to the metal plate to increase the roughness of the metal plate surface, There is a problem that seizure occurs due to the shortage.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a cold rolling technique capable of producing a metal plate having the same luster as that of a low-speed rolling by a Sendzimir mill without producing oil pits even at a high rolling speed. The purpose is to provide.

[0008]

Means for Solving the Problems The present inventor has proposed that even when a roll having a surface roughness approximately equal to that of a normal roll is rolled using a roll having a crater row substantially parallel to the roll axis direction. Has found that the surface glossiness of the metal plate is remarkably improved as compared with the conventional case where the roll is polished with a roll having a polished line in the circumferential direction. That is, the gist of the present invention resides in the following (1) to (4).

(1) A work roll having crater rows formed on the surface by laser processing, wherein the crater rows satisfy the following conditions:

[0010] The crater rows are arranged substantially parallel to the axial direction of the roll.

The crater row has a depth of 2 to 20 μm and a width of 2 to 20 μm.
It is 50 to 300 μm.

The circumferential repetition interval of the crater row is 50 to
800 μm.

(2) The length of one crater row in the axial direction is 3 to 50 times its width, and the crater row is repeated in the axial direction at an interval of 1 to 3 times its length. (1) The work roll for cold rolling.

(3) When laser processing is performed while rotating the work roll to process the surface of the roll, the number of rotations of the roll and the number of rotations of the chopper blade for blocking laser light are determined by the crater row. It is adjusted so that it is formed substantially in parallel with the axial direction.
Perform laser processing so that the laser beam advances in the axial direction by 0.1 to 1 times the crater diameter every rotation or several rotations
A method for producing the work roll for cold rolling according to (1) or (2).

(4) The metal plate is cold-rolled by using the cold-rolling work roll (1) or (2) at least at the final pass in the reversing mill rolling and at least the final stand in the tandem mill rolling. how to.

In the present invention, a crater means a minute unevenness formed on the surface of a metal plate when a metal plate is subjected to laser processing, and has a concave portion 1 shown in FIG. , Including the raised convex portion 2. When the convex portion is ground and used after the formation of the crater, the crater is only the concave portion. In addition, the crater row means that the craters are formed continuously and linearly.

The fact that the crater row is substantially parallel to the axial direction of the roll means that the crater row has an irregular arrangement such as a slight bend or that the crater row is slightly (axial) with respect to the roll axis. (Approximately ± 5 to 6 degrees with respect to the direction), such deviation of the error range is allowed, and the concave portions of adjacent crater rows are parallel to each other so as not to overlap.

FIG. 2 is an enlarged view of a cross section in the circumferential direction of the roll. FIG. 2A shows a case where the circumferential repetition interval of the crater row (c in the figure) is large and the protrusions of the craters do not overlap. (B) is a diagram showing a case where the portions overlap each other, and (c) is a diagram showing a case where polishing is performed after forming the crater row in the state of (a). The crater depth in the present specification is:
In cases (a) and (b), it refers to the distance from the top of the projection to the bottom of the recess, and in case (c), the distance from the flat portion between the craters to the bottom of the recess. I do. The width of the crater row means the distance between the vertices at both ends (a in the figure). In the case of (c), it is the distance between the flat portion and the adjacent flat portion.

FIG. 3 is a plan view in the case where the crater rows are repeatedly present with an appropriate length in the axial direction. The hatched portion in this figure is a portion encased at the apex of the convex portion, and is an example of a case where the roll surface is spirally masked and laser-processed. In the figure, a and c represent the crater width and its circumferential repetition interval as in FIG. 2, b represents the axial length of the crater row, and d represents its axial repetition interval.

[0020]

FIG. 4 is a view for explaining that a roll surface and a metal plate surface slip during cold rolling. (a) is a cross-sectional view in the rolling longitudinal direction of the roll bite portion, and (b) is a diagram showing a locus drawn on a metal plate by a point on the roll.
If the roll 1 is cold-rolled in the direction of X such that the thickness t ₂ of the metal plate S from the thickness t _1, the rolling speed v of the metal plate S
Is the neutral point (point N in the figure)
Call. The N backward (roll entry side) is referred to as the reverse range than point, the rolling speed at the point A in FIG. And v _1. Also,
The area ahead of the point N (roll exit side) is called the advanced area, and B in the figure
The rolling speed at the point and v _2. At this time, v ₁ <v ₂
It is.

Therefore, the roll peripheral speed V and the rolling speeds v ₁ and v ₂ of the metal plate S are v ₁ <V <v ₂ , and the rolling speeds of the metal plate in the advanced zone and the reverse zone are different. When a point above rotates in the directions of points A, N and B, this point draws a locus as shown in FIG. As shown in this figure, it can be seen that a trajectory that is opposite to the rolling direction is drawn in the advanced region.

FIG. 5 shows the transfer of a roll polishing pattern (hereinafter referred to as a transfer pattern) formed on the surface of a metal plate when cold rolling is performed using a normal roll whose polishing direction is parallel to the roll circumferential direction. FIG. When a roll whose polishing direction is parallel to the circumferential direction of the roll is rolled as shown in FIG. 5 (a), relative slip between the roll and the metal plate occurs as described above. As a result, the roll 1 has a sliding flaw on the surface of the metal plate S. Therefore, in addition to the transfer of the polished stitches of the roll 1 to the surface of the metal plate S, a long sliding flaw is formed in the circumferential direction.
As shown in the figure, the surface of the roll polishing surface is emphasized. When the roll polishing line is parallel to the circumferential direction,
Since the oil pit generated at this time cannot be crushed, the oil pit remains as shown in FIG.

On the other hand, a transfer pattern when cold rolling is performed using the roll of the present invention will be described with reference to FIG. At this time, as described with reference to FIG. 5, the metal plate S and the roll 1 slip as shown in FIG. 6B, and a long crater row slides in the roll axis direction, so that the metal plate S Has long sliding flaws in the roll axis direction. The surface of the metal plate S is partially smoothed due to the presence of the sliding flaw. Therefore, the transferred traces of the crater rows and the generated oil pits are crushed and disappear by the crater rows, and the cross section of the rolled metal plate in the width direction and the rolling direction is shown in FIG. A smooth surface as shown in FIG. The minute convex shape generated on the surface is a shape in which the surface of the metal plate is swelled into the concave portion of the roll when slippage occurs.

FIG. 7 shows an enlarged plan view and a cross-sectional shape of the surface of the metal plate after cold rolling has been performed with a roll having an abrasive grain parallel to the circumferential direction of the roll. FIG. 8 is an enlarged plan view and a cross-sectional view of the surface of the metal plate after cold rolling with the roll of the present invention.

In both figures, the scale of the cross-sectional shape in the direction perpendicular to the plate (thickness direction of the plate) is set to be 100 times larger than the transverse direction (the plate longitudinal direction or the plate width direction) of the plate cross section. Comparing the two figures, the case of rolling using the roll of the present invention (case of FIG. 8) is smoother than the case of rolling using the conventional roll (case of FIG. 7). It has a cross-sectional shape, and it can be seen that oil pits are reduced.

In the present invention, a laser processing method is used as a method for forming the crater rows on the roll. Normal,
In the method of forming the polishing line by polishing, it is necessary to adjust the position and speed of the roll and the grindstone in a complicated manner so that the polishing line is in the axial direction, and the finished roughness in the width direction is not uniform due to the wear of the grinding wheel. It is easy to be uniform.

The effect of the present invention can be obtained even if the crater row is inclined to a certain degree with respect to the roll axis. However, when the crater row is substantially parallel to the roll axis, stress is applied in the axial direction. It is the most efficient because no twist deformation occurs.

FIGS. 9 (a), 9 (b), 9 (c) and 9 (d) are views for explaining the continuous formation of craters. Are classified according to the relationship between the center distance L and the outer diameter D of the crater. As shown in FIG.
When / D is 1 or more, craters do not overlap with each other, so that the object intended in the present invention cannot be achieved. Conversely, if the L / D is less than 0.1, the thermal effect of the laser beam on the roll is remarkable, so that the surface of the roll is softened and the unevenness tends to disappear due to abrasion. That is, adjacent craters in the same crater row are L / D
Is preferably processed so as to overlap within a range of 0.1 to 1. The “crater row” of the present invention also includes those in which L / D is 1 and the recesses are not actually in contact with each other.

In order to perform such processing, the number of rotations of the work roll and the number of rotations of the chopper blade for blocking the laser beam are adjusted so that the craters are formed side by side in the axial direction. Laser processing may be performed so that the laser beam advances in the axial direction by 0.1 to 1 times the crater diameter every one rotation or several rotations. Specifically, the number of rotations of the roll is one or an integer times the number of rotations of the chopper blade. What is necessary is just to adjust and process it. In addition,
When this crater row is used with an appropriate length, the object can be achieved by performing masking at equal intervals in the axial direction on the roll surface before processing and then performing the processing. This masking is preferably performed in a spiral shape from the viewpoint of workability and finished shape. For masking, a material that reflects or absorbs laser light, such as a wire such as steel, aluminum, or copper, or a metal foil having an appropriate thickness and width may be used.

The appropriate depth of the crater row is 2 to 20 μm. If it is less than 2 μm, not only is it difficult to process, but also the oil pits tend to occur because the unevenness of the roll is too small compared to the oil film thickness. On the other hand, if it exceeds 20 μm, the surface of the metal plate has too much sliding flaws. When the craters do not overlap each other as shown in FIG. 2 (a) and the projection is used without grinding, the distance from the top of the projection to the bottom of the recess is 2 to 20 μm.
And the width of the convex portion is preferably 5 to 50 μm. If it is less than 5 μm, it is easy to wear, and if it exceeds 50 μm, the number of protrusions present in the contact arc (A → N → B in FIG. 4) during rolling is reduced, and the smoothing action due to slip is reduced. In this case, the depth of the concave portion (the distance between the apex of the convex portion and the surface of the base material) existing between the crater portion and the adjacent crater portion does not exceed the depth of the crater by laser processing.

The appropriate width of the crater row is 50 to 300 μm. If it is less than 50 μm, the difference between the concave portion and the convex portion is small, so that it is easy to wear during rolling. If it exceeds 300 μm, the number of protrusions existing in the contact arc during rolling (A → N → B in FIG. 4) decreases, and the smoothing effect due to slip decreases.

In addition, the crater rows are 50 to 50 in the circumferential direction of the roll.
It should be present at a repetition interval of 800 μm. If it is less than 50 μm, the vertices of the crater projections overlap, and it is difficult to obtain an accurate crater arrangement. If it exceeds 800 μm, smoothing cannot be performed uniformly.

The repetition interval does not need to be constant as long as the effect of the present invention is achieved. When the repetition interval is large when the width of the crater row is small, the smoothing effect may be reduced. In such a case, the repetition interval is preferably set to 500 μm or less.

The crater row of the roll according to the present invention may be continuously connected to the roll in the axial direction, but when the length of the continuous continuation in the axial direction exceeds 15000 μm, the action of scraping the rolling oil into the roll bite portion greatly works. Therefore, the oil film becomes thick, and the smoothed state of the surface is easily affected by the rolling speed.
At this time, it is preferable to set the thickness to less than 15000 μm from the viewpoint that abrasion powder of the metal plate generated by the smoothing easily accumulates in the concave portion of the crater and the depth of the groove portion is difficult to be constant. this,
Considering the balance between the action of rolling oil into the crater portion and the effect of grinding the surface of the metal plate, the axial length of the crater row is preferably 3 to 50 times its width.

At this time, the repetition interval in the axial direction is desirably 1 to 3 times the length in the axial direction so that the smoothing can be performed as uniformly as possible.

When performing cold rolling using the roll of the present invention, at least in the final pass when using a reversing mill,
In the case of using a tandem mill, at least when applied to the final stand, in addition to the effect of smoothing the oil pits, it is also possible to smooth the seizure flaws and slip flaws generated on the surface of the metal plate in the previous pass or stand. it can.

Next, the present invention will be described based on examples.

[0038]

Example 1 The surface of a JIS SUJ-2 steel roll having a diameter of 380 mmφ and a length of 400 mm was polished to obtain a bright roll having a maximum height (Rmax) of 0.5 μm. in it with C0 ₂ laser beam processing machine, pulse frequency: 20000 Hz, ^{power: 4 × 10 6 W / cm} 2
The surface was processed.

At this time, various rolls shown in Table 1 were obtained by adjusting the number of rotations of the roll, the number of rotations of the chopper blade, and the feed speed of the laser beam in the roll axis direction.

Using these rolls, SUS430 steel (thickness 3.2 mm, width 100 mm, hot-rolled annealed material, pickled) was rolled in 4-
Cold rolling was performed up to 5 passes using a Hi5 stand tandem rolling mill according to the rolling schedule shown in Table 2. As a conventional roll, a normal roll having a polishing line in the circumferential direction of the roll was used. Table 3 shows the rolls used in each pass and the properties of the metal plate surface after rolling. As a lubricating oil during rolling, synthetic ester-based rolling oil (viscosity at 50 ° C of 10 cSt
And two 25 cSt) 3% emulsions.

The rolls Nos. 1 to 4 were used as they were after the laser processing, and the rolls Nos. 5 to 7 were used after the laser processing and the protruding portions were ground.

The glossiness in Table 3 was evaluated in terms of specular glossiness (Gs45 °) at a measurement angle of 45 ° according to JIS: 450 or more as ○, 300 or more and less than 450 as Δ, and less than 300 as ×. Regarding the presence or absence of uneven gloss, oil pits, and seizure flaws, the presence was indicated by x, and the absence was indicated by ○. Even if they were present, they were marked as △ if they were insignificant so as not to cause a problem. In the overall evaluation, if there was at least one x, the result was evaluated as x, all cases were evaluated as ○, and other cases, that is, when both ○ and △ were mixed, were evaluated as ○.

As can be seen from Table 3, when the roll of the present invention is rolled using at least the final pass, glossiness, gloss unevenness, and the like are reduced as compared with the case of rolling with a conventional roll.
It can be seen that both oil pits and seizure flaws are significantly improved.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

Example 2 After winding a wire made of aluminum having a diameter of 450 μm on the surface of the roll at a pitch of 2500 μm in a helical manner so that the winding angle is 30 ° with respect to the circumferential direction of the roll, the same as in Example 1 was carried out. Surface treatment was performed in the same manner to produce the rolls shown in Table 4. FIG. 10 shows a schematic view of performing this processing by performing masking. As lubricating oil, synthetic ester rolling oil (viscosity at 50 ° C of 10 cSt, 25 cSt, 50 cSt
Cold rolling was performed in the same manner as in Example 1 except that a 3% emulsion was used.

The rolls Nos. 12 to 15 were used as they were after the laser processing, and the rolls Nos. 16 to 18 were used after the laser processing and the protruding portions were ground.

Table 5 shows the rolls used in each pass and the properties of the metal plate surface after rolling.

As can be seen from Table 5, when the roll of the present invention is rolled using at least the final pass, the glossiness, gloss unevenness, and the like are reduced as compared with the case of rolling with the conventional roll.
It can be seen that both oil pits and seizure flaws are significantly improved. Further, it can be seen that the rolling oil shows a high glossiness even with a high viscosity oil of 25 cSt or more.

[0051]

[Table 4]

[0052]

[Table 5]

[0053]

When the roll of the present invention is used at the time of cold rolling, oil pits, slip flaws, and seizure flaws are less likely to occur even at a high rolling speed. That is, a metal plate having excellent glossiness can be rolled with high productivity.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross-sectional shape of a crater formed on a roll surface by laser processing.

FIG. 2 is a diagram illustrating the width of a crater and the circumferential repetition interval of a crater row.

FIG. 3 is a plan view of the roll surface when the crater row is repeated with an appropriate length in the axial direction.

FIG. 4 is a diagram illustrating that a roll surface and a metal plate surface slip during cold rolling. (a) is a cross-sectional view in the rolling longitudinal direction of the roll bite portion, and (b) is a diagram showing a locus drawn on a metal plate by a point on the roll.

FIG. 5 is a diagram illustrating the transfer of roll polishing eyes formed on the surface of a metal plate when cold rolling is performed using a normal roll whose polishing direction is a circumferential direction.

FIG. 6 is a diagram illustrating a transfer pattern when cold rolling is performed using the roll of the present invention.

FIG. 7 is an enlarged plan view and a cross-sectional view of the surface of a metal plate after performing cold rolling with a conventional roll having a polished edge in the circumferential direction of the roll.

FIG. 8 is an enlarged plan view and a cross-sectional view of the surface of a metal plate after performing cold rolling with the roll of the present invention.

FIG. 9 is a diagram illustrating a form of a crater arrangement in a roll axis direction.

FIG. 10 is a schematic diagram showing a state in which processing for forming a crater row on a roll by performing masking is performed.

[Explanation of symbols]

1. 1. recess (of the crater); Convex part (of crater),
3. Base material surface, a. Crater width, b. Crater length, c. Circumferential repeat interval (for crater rows),
d. Axial repetition interval (of crater rows), Metal plate,
R. Roll, L. Crater center distance,
D. Crater outer diameter, M. Masking, LB.
Laser light

Claims (4)

(57) [Claims] 1. A work roll having a crater row formed on its surface by laser processing, wherein the crater row is:
A work roll for cold rolling, which satisfies the following conditions: The crater rows are arranged substantially parallel to the axial direction of the roll. Crater rows have a depth of 2-20 μm and a width of 50-300 μm
It is. The repetition interval in the circumferential direction of the crater row is 50 to 800 μ
m. 2. The length of one crater row in the axial direction is 3 to 50 times its width, and the crater row is repeated in the axial direction at an interval of 1 to 3 times the axial length. The work roll for cold rolling according to claim 1, wherein: 3. When the laser processing is performed while rotating the work roll to process the surface of the work roll, the number of rotations of the work roll and the number of rotations of the chopper blade for blocking the laser beam are determined by the crater row. The laser processing is performed such that the laser beam is advanced in the axial direction by 0.1 to 1 times the crater diameter each time the work roll makes one or several rotations. The method for producing a work roll for cold rolling according to claim 1 or 2, wherein: 4. A cold rolling work roll according to claim 1 or 2, wherein at least a final pass is used for rolling in a reversing mill, and at least a final stand is used for rolling in a tandem mill. Cold rolling method.