Method for rolling sheet to be rolled

Abstract

To provide a method for rolling a sheet to be rolled, which can eliminate meander and camber of a sheet to be rolled which are caused by a lateral difference in friction coefficient between a work-roll and the sheet to be rolled, by a control end other than the lateral difference in friction coefficient, in cross rolling.SOLUTION: In cross rolling in which a rolling machine provided with a pair of work rolls crossed each other in a rolling surface rolls a sheet to be rolled, a meander amount of the sheet to be rolled is measured at least at either of an inlet side and an outlet side of the rolling machine, and a vertical difference in friction coefficient between the work-rolls and the sheet to be rolled is adjusted on the basis of the meander amount of the sheet to be rolled. This can eliminate the meander of the sheet to be rolled, without applying a wedge to the sheet to be rolled.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a method for rolling a plate in cross rolling, in which the plate is rolled by a rolling mill having a pair of work rolls crossed in the rolling plane. [Background technology]

[0002] It is known that meandering and camber of a rolled sheet occur due to asymmetry in the rolling state. One example of the asymmetry in the rolling state is the difference in the reduction rate between the left and right sides, i.e., a change in the wedge ratio. In order to suppress the occurrence of meandering and camber, many methods have been proposed for eliminating the asymmetry in the rolling state by reducing the difference in the reduction rate between the left and right sides, i.e., by leveling the difference, thereby bringing the change in the wedge ratio closer to zero (for example, Patent Document 1).

[0003] Here, a factor that can cause left-right asymmetry in the rolling state other than changes in the wedge ratio is an asymmetric distribution of the friction coefficient, i.e., a difference between the left and right friction coefficients. For example, Patent Document 2 describes that if camber occurs while rolling a metal material with its widthwise movement restrained at the entry side of the rolling mill, a friction coefficient adjusting means is used to adjust the friction coefficient between the outer region of the metal material and the work rolls of the rolling mill so that it becomes smaller. That is, the technique described in Patent Document 2 suppresses the occurrence of camber by controlling the difference between the left and right friction coefficients. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 61-269914 [Patent Document 2] Japanese Patent Application Publication No. 5-237528 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the difference in the coefficient of friction between the left and right rolls is unavoidable and changes over time due to, for example, differences in the roughness of the roll surface between the left and right rolls, differences in the surface properties of the rolled sheet between the left and right rolls, differences in the lubrication state between the left and right rolls, etc. Therefore, there has been a problem in that it is difficult to stably suppress meandering of the rolled sheet by controlling only the difference in the coefficient of friction between the left and right rolls. In other words, if the meandering and camber of the rolled sheet caused by the difference in the coefficient of friction between the left and right rolls could be eliminated by controlling factors other than the difference in the coefficient of friction between the left and right rolls, the flexibility of rolling operations could be improved.

[0006] A widely used method for suppressing meandering and camber in a rolled sheet is leveling control, which controls the difference in the amount of reduction between the left and right sides of the rolled sheet. However, leveling control results in a wedge (a difference in thickness between the left and right sides) in the rolled sheet.

[0007] Therefore, the present invention has been made in consideration of the above problems, and an object of the present invention is to provide a rolling method for a rolled sheet that can eliminate the meandering and camber of the rolled sheet that occur due to the difference in friction coefficient between the left and right sides in cross rolling by using a control end other than the difference in friction coefficient between the left and right sides. [Means for solving the problem]

[0008] To solve the above problems, the present inventors focused on the fact that in cross rolling using a cross rolling mill, such as a pair cross rolling mill, which has a pair of work rolls crossed in the rolling plane, meandering and camber occur in the rolled sheet due to the difference in the coefficient of friction between the top and bottom work rolls. As an extreme example, consider a situation where the top surface of the rolled sheet is stuck to the work roll and the bottom surface is completely sliding relative to the work roll. In other words, if there is a difference in the coefficient of friction between the top work roll and the rolled sheet and the bottom work roll and the rolled sheet, the rolled sheet will move in a direction perpendicular to the rotation axis of the work roll with the larger coefficient of friction, resulting in meandering and camber. Therefore, they believed that meandering and camber caused by the difference in the coefficient of friction between the left and right sides can be compensated for in cross rolling by the difference in the coefficient of friction between the top and bottom work rolls.

[0009] That is, according to one aspect of the present invention, there is provided a method for rolling a rolled sheet in cross rolling, in which the rolled sheet is rolled using a rolling mill equipped with a pair of work rolls crossed within the rolling plane, in which the amount of meandering of the rolled sheet is measured at least on either the entry side or exit side of the rolling mill, and the difference in the coefficient of friction between the work rolls and the rolled sheet is adjusted based on the amount of meandering of the rolled sheet.

[0010] Here, when the work rolls cross each other so that on the drive side of the rolling mill the upper work roll barrel is located on the exit side of the rolling mill relative to the lower work roll barrel, and on the work side of the rolling mill the upper work roll barrel is located on the entry side of the rolling mill relative to the lower work roll barrel, if the plate to be rolled meanders toward the drive side of the rolling mill on the exit side of the rolling mill, at least one of adjustments may be made to increase the coefficient of friction between the upper work roll and the plate to be rolled, or adjustments may be made to decrease the coefficient of friction between the lower work roll and the plate to be rolled, and if the plate to be rolled meanders toward the work side of the rolling mill on the exit side of the rolling mill, at least one of adjustments may be made to increase the coefficient of friction between the lower work roll and the plate to be rolled, or adjustments may be made to decrease the coefficient of friction between the upper work roll and the plate to be rolled

[0011] Furthermore, when the work rolls cross each other so that on the drive side of the rolling mill the upper work roll barrel is located on the exit side of the rolling mill relative to the lower work roll barrel, and on the work side of the rolling mill the upper work roll barrel is located on the entry side of the rolling mill relative to the lower work roll barrel, if the plate to be rolled meanders toward the drive side of the rolling mill at the entry side of the rolling mill, at least one of adjustments may be made to increase the coefficient of friction between the lower work roll and the plate to be rolled, or adjustments may be made to decrease the coefficient of friction between the upper work roll and the plate to be rolled, and if the plate to be rolled meanders toward the work side of the rolling mill at the entry side of the rolling mill, at least one of adjustments may be made to increase the coefficient of friction between the upper work roll and the plate to be rolled, or adjustments may be made to decrease the coefficient of friction between the lower work roll and the plate to be rolled

[0012] On the other hand, if the work rolls cross so that on the drive side of the rolling mill the upper work roll barrel is located on the entry side of the rolling mill relative to the lower work roll barrel, and on the work side of the rolling mill the upper work roll barrel is located on the exit side of the rolling mill relative to the lower work roll barrel, then if the plate to be rolled meanders toward the drive side of the rolling mill at the exit side of the rolling mill, at least one of adjustments to increase the coefficient of friction between the lower work roll and the plate to be rolled, or adjustments to decrease the coefficient of friction between the upper work roll and the plate to be rolled, may be made; and if the plate to be rolled meanders toward the work side of the rolling mill at the exit side of the rolling mill, at least one of adjustments to increase the coefficient of friction between the upper work roll and the plate to be rolled, or adjustments to decrease the coefficient of friction between the lower work roll and the plate to be rolled, may be made.

[0013] Furthermore, when the work rolls cross each other so that on the drive side of the rolling mill the upper work roll barrel is located on the entry side of the rolling mill relative to the lower work roll barrel, and on the work side of the rolling mill the upper work roll barrel is located on the exit side of the rolling mill relative to the lower work roll barrel, if the plate to be rolled meanders toward the drive side of the rolling mill at the entry side of the rolling mill, at least one of adjustments may be made to increase the coefficient of friction between the upper work roll and the plate to be rolled, or adjustments may be made to decrease the coefficient of friction between the lower work roll and the plate to be rolled, and if the plate to be rolled meanders toward the work side of the rolling mill at the entry side of the rolling mill, at least one of adjustments may be made to increase the coefficient of friction between the lower work roll and the plate to be rolled, or adjustments may be made to decrease the coefficient of friction between the upper work roll and the plate to be rolled

[0014] Here, the difference in the coefficient of friction between the upper and lower work rolls may be adjusted by changing the amount of lubricant supplied between the upper and lower work rolls.

[0015] Alternatively, the difference in the coefficient of friction between the upper and lower work rolls may be adjusted by changing the concentration of the lubricant between the upper and lower work rolls.

[0016] Furthermore, the difference in the coefficient of friction between the top and bottom work rolls may be adjusted by changing at least one of the surface roughness of the work rolls or the surface properties of the rolled sheet between the top work roll side and the bottom work roll side.

[0017] The rolling mill that rolls the plate to be rolled may be a pair cross rolling mill. [Effects of the Invention]

[0018] As described above, according to the present invention, meandering and camber of the rolled sheet caused by the difference in the coefficient of friction between the left and right sides in cross rolling can be eliminated by a control limit other than the difference in the coefficient of friction between the left and right sides. [Brief explanation of the drawings]

[0019] [Figure 1]1 is an explanatory diagram showing a configuration example of a rolling device according to an embodiment of the present invention; [Figure 2] FIG. 10 is an explanatory diagram showing the meandering state of the rolled sheet when the driving side friction coefficient μDS is larger than the work side friction coefficient μWS. [Figure 3] 10 is a graph showing an example of the relationship between the difference between the left and right friction coefficients and the amount of meandering of the rolled sheet. [Figure 4] FIG. 1 is an explanatory diagram showing a simple model used to predict the camber curvature of a rolled sheet on the delivery side of a rolling mill due to a difference in friction coefficient between the left and right sides. [Figure 5] 1 is an explanatory diagram showing the meandering state of a rolled sheet when the lower friction coefficient μBot is larger than the upper friction coefficient μTop. FIG. [Figure 6] 10 is a graph showing an example of the relationship between the difference between the upper and lower friction coefficients and the amount of meandering of the rolled sheet. [Figure 7] 3 is a flowchart showing an example of a rolling method for a rolled sheet according to the embodiment. [Figure 8] 8 is an explanatory diagram illustrating suppression of meandering of a rolled sheet by the rolling method of a rolled sheet shown in FIG. 7. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant explanations will be omitted.

[0021] [1. Configuration of rolling equipment] First, a schematic configuration of a rolling mill 1 equipped with a cross rolling mill 10 according to one embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is an explanatory diagram showing an example of the configuration of the rolling mill 1 according to this embodiment.

[0022] In the following description, the upstream side of the cross rolling mill 10 in the rolling direction (X direction) is also referred to as the "entrance side," and the downstream side of the cross rolling mill 10 in the rolling direction (X direction) is also referred to as the "exit side." The reference direction is the left-right direction of the cross rolling mill 10, i.e., the direction (Y direction) perpendicular to the rolling direction within the rolling plane (XY plane) on which the cross rolling mill 10 rolls the sheet S. The reference direction is the direction along the longitudinal direction of the barrels of the work rolls 11 and 12 (i.e., the roll axes). Here, when viewing the cross rolling mill 10 from the upstream side in the rolling direction, one side of the barrels of the work rolls 11 and 12 located on the right side (near the paper) is also referred to as the "working side," and the other side of the barrels of the work rolls 11 and 12 located on the left side (farther from the paper) is also referred to as the "drive side." Note that Figure 1 shows a schematic configuration of the rolling mill 1, and the work rolls 11, 12 are shown in a state where they have no cross angle, but in the cross rolling mill 10, at least one of the work rolls 11, 12 is installed so that the roll axis on the rolling surface has an angle with respect to a reference direction.

[0023] As shown in Fig. 1, the rolling mill 1 according to this embodiment comprises a cross rolling mill 10, a meandering meter 20, lubricant supply devices 31 and 32, and a control device 100. The cross rolling mill 10 has a top work roll 11 and a bottom work roll 12. At least one of the top work roll 11 and the bottom work roll 12 is installed so that the roll axis is angled with respect to a reference direction on the rolling surface, and they intersect within the rolling surface.

[0024] A meandering meter 20 for measuring the meandering amount of the rolled sheet S is installed on the delivery side of the cross rolling mill 10 shown in Figure 1. The meandering meter 20 may also be installed on the entry side of the cross rolling mill 10. The type of meandering meter 20 is not particularly limited, and for example, an image of the rolled sheet S may be taken with a CCD camera, and the edge position of the rolled sheet S may be detected by image processing to calculate the meandering amount. Measurement information from the meandering meter 20 is output to the control device 100.

[0025] At the entry side of the cross rolling mill 10, a lubricant supplying device 31 that supplies lubricant to the upper work roll 11 and a lubricant supplying device 32 that supplies lubricant to the lower work roll 12 are arranged. The lubricant supplying devices 31, 32 may be configured, for example, by arranging multiple flat spray nozzles along the length of the roll barrels of the work rolls 11, 12. While the present embodiment illustrates the case where the lubricant is sprayed onto the work rolls 11, 12, it may also be sprayed onto the rolled sheet S or the auxiliary rolls. For example, a synthetic ester-based lubricant oil commonly used as a hot rolling oil may be used as the lubricant. The lubricant supplying devices 31, 32 operate independently, and the amount and concentration of lubricant supplied by the upper lubricant supplying device 31 and the lower lubricant supplying device 32 can be changed based on control information from the control device 100.

[0026] The control device 100 performs various controls of the rolling mill 1. In this embodiment, the control device 100 controls the rolling mill 1, for example, so that the meandering amount of the rolled sheet S obtained based on the detection results of the meandering meter 20 becomes zero. At this time, the control device 100 changes the amount and concentration of lubricant supplied by the lubricant supply devices 31 and 32, changes the amount of grinding of the surfaces of the top work roll 11 and the bottom work roll 12 by a roll grinding device (not shown) installed in the cross rolling mill 10, and changes the pressure and flow rate of descaling water on the top and bottom sides of the rolled sheet S by a descaling device (not shown) installed upstream of the cross rolling mill 10. In this way, it is possible to adjust the difference in the coefficient of friction between the work rolls 11 and 12 and the rolled sheet S based on the amount of meandering of the rolled sheet S.

[0027] [2. Suppression of meandering of rolled sheets] [2-1. Relationship between the amount of meandering of the rolled sheet and the coefficient of friction] In a rolling mill, a difference in the coefficient of friction between the left and right sides can cause meandering or camber in the rolled sheet S. This phenomenon occurs regardless of the mill type. The coefficient of friction between the work rolls 11, 12 and the rolled sheet S on the drive side (DS) from the center of the width direction of the rolled sheet S (hereinafter also referred to as the "drive side coefficient of friction") is defined as μ DSThe coefficient of friction between the work rolls 11, 12 and the rolled sheet S on the work side (WS) from the center of the width direction of the rolled sheet S (hereinafter also referred to as the "work side coefficient of friction") is μ WS When this is the case, the friction coefficient on the driving side μ DS and the working side friction coefficient μ WS If there is a difference between the left and right sides, the direction of travel of the rolled sheet S will be inclined to the side with the smaller coefficient of friction.

[0028] For example, consider a rolling mill in which the top work roll 11 and bottom work roll 12 are arranged perpendicular to the rolling direction, as shown in Figure 2. In this case, it is assumed that there is no difference between the coefficient of friction between the top work roll 11 and the rolled sheet S and the coefficient of friction between the bottom work roll 12 and the rolled sheet S on the drive side (DS) and work side (WS) of the width center of the rolled sheet S. In the following explanation, it is assumed that there is no wedge in the rolled sheet S. Furthermore, the amount of meandering of the rolled sheet S is represented as zero when there is no meandering, with meandering towards the drive side (DS) being a positive value and meandering towards the work side (WS) being a negative value.

[0029] In such a rolling mill, the driving side friction coefficient μ DS is the working side friction coefficient μ WS If the coefficient of friction on the drive side is larger than , the rolled sheet S will snake towards the work side (WS) at the exit side of the rolling mill, as shown in Figure 2. DS and the working side friction coefficient μ WS Left-right difference Δμ DW (=μ DS -μ WS ) increases, the amount of meandering of the rolled sheet S at the delivery side of the rolling mill increases in the negative direction, as shown in Figure 3. On the other hand, the work-side friction coefficient μ WS is the driving side friction coefficient μ DS If the friction coefficient μ is larger than 1 / μm, the rolled sheet S will snake toward the drive side (DS) at the exit side of the rolling mill. DS and the working side friction coefficient μ WS Difference between left and right Δμ DW (=μ DS -μ WS ) becomes smaller (i.e., the absolute value |Δμ DW| increases), the amount of meandering of the rolled sheet S at the delivery side of the rolling mill increases in the positive direction.

[0030] Here, it was also found that the meandering direction of the rolled sheet S due to the difference in the coefficient of friction between the left and right sides is characterized by being opposite on the entry side and exit side of the rolling mill. It was also found that the meandering of the rolled sheet S due to the difference in the coefficient of friction between the left and right sides is characterized by not being accompanied by a change in the wedge ratio of the rolled sheet S. Therefore, if this is compensated for by leveling control, not only will wedges occur in the rolled sheet S, but it will also result in a phenomenon in which trying to suppress meandering on the exit side of the rolling mill will increase meandering on the entry side of the rolling mill, and conversely, trying to suppress meandering on the entry side of the rolling mill will increase meandering on the exit side of the rolling mill.

[0031] The inventors of the present application have conducted numerical analysis and experiments to determine the difference in the friction coefficient between the left and right Δμ DW It was clarified that the mechanism by which meandering and camber occur in the rolled sheet S due to the friction coefficient is as follows. Figure 4 shows a simple model used to predict the camber curvature κ of the rolled sheet S at the delivery side of the rolling mill due to the difference in the friction coefficient between the left and right sides. In Figure 4, the friction coefficient μ WS is the driving side friction coefficient μ DS For the sake of simplicity, the rolled sheet S is separated into left and right halves, and the forward slip ratio f s Calculate the longitudinal velocity V at the roll bite exit surface. out Let the peripheral speed of the work rolls 11 and 12 be V R , the leading rate is f s Then, the exit speed V of the rolled sheet S at the work side (WS) out WS , the exit speed V of the rolled sheet S on the drive side (DS) out DS are calculated using the following formulas (1) and (2), respectively.

[0032]

number

[0033] Here, the forward rate f sThe higher the friction coefficient μ, the lower the forward slip rate f s It is known that the higher the friction coefficient μ, the greater the exit speed V out It will also be faster.

[0034] In this way, the exit speed V out Since the rolled sheet S, which has a difference in width between the left and right sides, deforms as a single unit, a camber with a curvature κ with the high-speed side on the outside is generated in the rolled sheet S at the exit of the roll bite. If the width of the rolled sheet S is W and the angle of the camber is θ, the following equations (3) and (4) are obtained.

[0035]

number

[0036] From the above formulas (1) to (4), the following formula (5) is obtained.

[0037]

number

[0038] Meanwhile, the inflow velocity of the rolled sheet S into the roll bite is determined based on the sheet thickness and outflow velocity at the inlet and outlet sides, so as to maintain a constant volume. Therefore, the inflow velocity of the rolled sheet S on the side with the faster outflow velocity, i.e., the side with the larger friction coefficient, is faster than the inflow velocity of the rolled sheet S on the side with the smaller friction coefficient. Therefore, a camber occurs on the rolled sheet S at the inlet side of the roll bite, with the side with the larger friction coefficient facing inward, through a mechanism similar to that which causes camber on the rolled sheet S at the outlet side of the roll bite. In the experiment, due to the influence of material flow and constraints between the left and right rolled sheets, the camber curvature κ was smaller than the value calculated by Equation (5). However, the positive / negative difference in the left and right friction coefficients, the meandering of the rolled sheet S at the inlet and outlet sides of the roll bite, and the direction of the camber were consistent with the directions predicted based on the above estimations.

[0039] In this way, the difference in the friction coefficient between the left and right Δμ DWIt is thought that this appears as a widthwise distribution of the longitudinal speed of the rolled sheet S through the difference between the left and right front-reverse rates. DW When there is a difference in the friction coefficient between the left and right, it is clear that the direction of the camber generated in the rolled sheet S is different between the entry side and the exit side of the roll bite. DW It can be seen that when there is a difference in leveling (difference between the wedge and the amount of reduction between the left and right sides) in the rolled sheet S, the rolled sheet S will meander.

[0040] On the other hand, in cross rolling, it is known that meandering and camber occur in the rolled sheet S due to the difference in the friction coefficient between the top and bottom. The friction coefficient μ between the top work roll 11 and the rolled sheet S (hereinafter also referred to as the "upper friction coefficient") Top and the coefficient of friction between the bottom work roll 12 and the rolled sheet S (hereinafter also referred to as the "lower side coefficient of friction") μ Bot When there is a difference between the upper and lower work rolls, the direction of travel of the rolled sheet S is inclined in a direction perpendicular to the rotation axis of the work roll on the side with the larger coefficient of friction.

[0041] For example, consider a pair cross rolling mill in which the drive side (DS) of the barrel of the top work roll 11 is located downstream in the rolling direction and the work side (WS) of the barrel is located upstream in the rolling direction, as shown in Figure 5, and the drive side (DS) of the barrel of the bottom work roll 12 is located upstream in the rolling direction and the work side (WS) of the barrel is located downstream in the rolling direction. In this case, it is assumed that there is no difference in the coefficient of friction between the work rolls 11, 12 and the sheet S to be rolled. In the following explanation, it is assumed that there is no wedge in the sheet S to be rolled. Furthermore, the amount of meandering of the sheet S to be rolled is represented as zero when there is no meandering, with meandering toward the drive side (DS) being a positive value and meandering toward the work side (WS) being a negative value.

[0042] In such a pair cross rolling mill, the lower friction coefficient μ Bot is the upper friction coefficient μ Top , as shown in Figure 5, the rolled sheet S snakes toward the drive side (DS) at the exit side of the pair cross rolling mill so as to approach a direction perpendicular to the rotation axis of the bottom work roll 12. Botand the upper friction coefficient μ Top The difference Δμ BT (=μ Bot -μ Top ) increases, the amount of meandering of the rolled sheet S at the delivery side of the pair cross rolling mill increases in the positive direction, as shown in Figure 6. On the other hand, the upper friction coefficient μ Top is the lower friction coefficient μ Bot When the lower friction coefficient μ is larger than 1 / μm, the rolled sheet S snakes toward the work side (WS) at the exit side of the pair cross rolling mill so as to approach a direction perpendicular to the rotation axis of the upper work roll 11. In this case, the lower friction coefficient μ Bot and the upper friction coefficient μ Top The difference Δμ BT (=μ Bot -μ Top ) becomes smaller (i.e., the absolute value |Δμ BT | increases), the amount of meandering of the sheet S to be rolled in pair cross rolling increases in the negative direction.

[0043] Furthermore, the meandering direction of the rolled sheet S due to the difference in the coefficient of friction between the top and bottom in pair cross rolling is characterized in that it is opposite on the entry side and exit side of the rolling mill. In addition, it was also discovered that the meandering of the rolled sheet S due to the difference in the coefficient of friction between the top and bottom in pair cross rolling is characterized in that it is not accompanied by a change in the wedge ratio of the rolled sheet S.

[0044] Thus, when rolling a rolled sheet S, meandering and camber occur in the rolled sheet S due to the difference in the coefficient of friction between the left and right sides, and in pair cross rolling, meandering and camber occur in the rolled sheet S due to the difference in the coefficient of friction between the top and bottom. Based on the knowledge that meandering of the rolled sheet S is caused not only by the difference in the coefficient of friction between the left and right sides but also by the difference in the coefficient of friction between the top and bottom in pair cross rolling, the inventors of the present application conceived that meandering of the rolled sheet S caused by the difference in the coefficient of friction between the left and right sides, which is unavoidable and changes over time, can be suppressed by adjusting the difference in the coefficient of friction between the top and bottom in a pair cross rolling mill. If meandering of the rolled sheet S caused by the difference in the coefficient of friction between the left and right sides, which is unavoidable and changes over time, can be eliminated by adjusting the difference in the coefficient of friction between the top and bottom in a pair cross rolling mill, the flexibility of rolling operations can be improved.

[0045] Furthermore, the meandering of the rolled sheet S caused by the difference in the coefficient of friction between the left and right sides is in the opposite direction at the entry and exit of the rolling mill, just like the meandering of the rolled sheet S caused by the difference in the coefficient of friction between the top and bottom in pair cross rolling. Therefore, unlike compensation by leveling control, in pair cross rolling, by appropriately providing a difference in the coefficient of friction between the top and bottom, the meandering of the rolled sheet S caused by the difference in the coefficient of friction between the left and right sides can be compensated for and offset at both the entry and exit of the rolling mill. In addition, like the meandering of the rolled sheet S caused by the difference in the coefficient of friction between the top and bottom in pair cross rolling, the meandering of the rolled sheet S caused by the difference in the coefficient of friction between the left and right sides does not involve a change in the wedge ratio of the rolled sheet S. Therefore, unlike compensation by leveling control, if the meandering of the rolled sheet S caused by the difference in the coefficient of friction between the left and right sides in pair cross rolling is compensated for and offset by providing a difference in the coefficient of friction between the top and bottom, no wedging occurs in the rolled sheet S.

[0046] [2-2. Rolling method for rolled sheet] The rolling method for a rolled sheet S according to this embodiment will be described below with reference to Figures 1, 7, and 8. Figure 7 is a flowchart showing an example of the rolling method for a rolled sheet S according to this embodiment. Figure 8 is an explanatory diagram illustrating suppression of meandering of the rolled sheet S by the rolling method for a rolled sheet S shown in Figure 7. In the following description, it is assumed that the cross rolling mill 10 is a pair cross rolling mill, and that in this pair cross rolling mill, as shown in Figure 8, the work rolls 11, 12 cross so that on the drive side of the rolling mill, the top work roll barrel is located on the exit side of the rolling mill relative to the bottom work roll barrel, and on the working side of the rolling mill, the top work roll barrel is located on the entry side of the rolling mill relative to the bottom work roll barrel.

[0047] In the rolling method for the rolled sheet S according to this embodiment, first, the meandering amount of the rolled sheet S at the delivery side of the cross rolling mill 10 is measured by the meandering meter 20 installed at the delivery side of the cross rolling mill 10 (S10). The meandering meter 20 outputs the measurement results to the control device 100. The control device 100 calculates the meandering amount based on the measurement results.

[0048] Next, the control device 100 determines the direction of meandering of the rolled sheet S at the delivery side of the cross rolling mill 10 based on the calculated meandering amount (S20). If a state in which there is no meandering is represented as zero, and meandering toward the drive side (DS) is represented as a positive value, and meandering toward the work side (WS) is represented as a negative value, it can be determined that if the meandering amount is a positive value, the rolled sheet S is meandering toward the drive side (DS) at the delivery side of the cross rolling mill 10, and if the meandering amount is a negative value, the rolled sheet S is meandering toward the work side (WS) at the delivery side of the cross rolling mill 10.

[0049] For example, in the pair cross rolling mill shown in Fig. 8, in the state shown in the upper part of Fig. 8, the rolled sheet S snakes toward the drive side (DS) at the delivery side of the rolling mill. Here, as explained based on Figs. 2 to 4, the work side friction coefficient μ WS is the driving side friction coefficient μ DS When the work side friction coefficient μ is larger than 1 / μm, the rolled sheet S snakes toward the drive side (DS) at the exit side of the rolling mill. Therefore, in the state shown in the upper part of Figure 8, WS is the driving side friction coefficient μ DS It can be seen that the state is larger than

[0050] In step S20, the control device 100 determines the direction of meandering of the rolled sheet S at the delivery side of the cross rolling mill 10, and then calculates the difference Δμ between the upper and lower friction coefficients between the work rolls 11, 12 and the rolled sheet S so as to eliminate the meandering. BT As explained based on Fig. 5 and Fig. 6, in the pair cross rolling mill having the configuration shown in Fig. 8, the upper friction coefficient μ Top is the lower friction coefficient μ Bot When the lower friction coefficient μ is larger than 1 / μ, the rolled sheet S snakes toward the work side (WS) at the exit side of the pair cross rolling mill. Bot is the upper friction coefficient μ Top If the rolling speed is larger than 1 / 2, the rolled sheet S will snake toward the drive side (DS) at the delivery side of the pair cross rolling mill.

[0051] Based on this knowledge, when the rolled sheet S meanders toward the work side (WS) at the delivery side of the cross rolling mill 10, the control device 100 calculates the lower friction coefficient μ Bot is the upper friction coefficient μ Top(i.e., the lower friction coefficient μ Bot >Upper friction coefficient μ Top ) the lower friction coefficient μ Bot Adjustment to increase the upper friction coefficient μ Top At least one of the adjustments to reduce the

[0052] On the other hand, when the rolled sheet S meanders toward the drive side (DS) at the delivery side of the cross rolling mill 10, the control device 100 calculates the upper friction coefficient μ Top is the lower friction coefficient μ Bot (i.e., the upper friction coefficient μ Top > Lower friction coefficient μ Bot ) the lower friction coefficient μ Bot Adjustment to reduce the upper friction coefficient μ Top In this way, as shown in the lower part of Fig. 8, the meandering caused by the difference in the coefficient of friction between the left and right sides during rolling of the rolled sheet S is offset by the meandering caused by the difference in the coefficient of friction between the top and bottom, thereby suppressing the meandering.

[0053] Specifically, the difference in the coefficient of friction between the upper and lower work rolls in steps S30 and S40 can be adjusted by, for example, changing the amount or concentration of lubricant supplied by the upper lubricant supply device 31 and the lower lubricant supply device 32, or by changing at least one of the surface roughness of the upper work roll 11 or the lower work roll 12 or the surface properties of the rolled sheet S.

[0054] Increasing the amount of lubricant supplied by the lubricant supply devices 31, 32 reduces the coefficient of friction between the work rolls 11, 12 and the rolled sheet S. In addition, increasing the concentration of the lubricant supplied by the lubricant supply devices 31, 32 reduces the coefficient of friction between the work rolls 11, 12 and the rolled sheet S. Therefore, in step S30, the lower friction coefficient μ Bot To increase the upper friction coefficient μ, for example, the amount of lubricant supplied from the lubricant supply device 32 may be reduced or the concentration may be lowered. TopTo reduce this, for example, the amount of lubricant supplied from the lubricant supply device 31 may be increased or the concentration of the lubricant may be increased.

[0055] On the other hand, in step S40, the upper friction coefficient μ Top To increase the lower friction coefficient μ, for example, the amount of lubricant supplied from the lubricant supply device 31 may be reduced or the concentration may be lowered. Bot To reduce this, for example, the amount of lubricant supplied from the lubricant supply device 32 may be increased or the concentration of the lubricant may be increased.

[0056] The difference in the coefficient of friction between the work rolls 11, 12 and the sheet S to be rolled is Δμ BT When adjusting the lubricant supply amount, either one of the lubricant supply devices 31 and 32 may be operated, or both of the lubricant supply devices 31 and 32 may be operated.

[0057] The coefficient of friction between the work rolls 11, 12 and the sheet S to be rolled can also be adjusted by changing the surface roughness of the work rolls 11, 12 or the surface properties of the sheet S to be rolled. For example, by grinding the surfaces of the work rolls 11, 12 using a roll grinding device (not shown) installed in the cross rolling mill 10, the surface roughness of the work rolls 11, 12 can be reduced, thereby reducing the coefficient of friction between the work rolls 11, 12 and the sheet S to be rolled. Therefore, in step S30, the lower friction coefficient μ Bot is the upper friction coefficient μ Top If it is desired to adjust the upper friction coefficient μ to be larger than 1, for example, the roll surface of the upper work roll 11 may be ground to adjust the upper friction coefficient μ Top On the other hand, in step S40, the upper friction coefficient μ Top is the lower friction coefficient μ Bot If it is desired to adjust the lower friction coefficient μ to be larger than 1 / 2, for example, the roll surface of the bottom work roll 12 may be ground to adjust the lower friction coefficient μ Bot can be made smaller.

[0058] Similarly, by improving the surface quality of the rolled sheet S by increasing the pressure and flow rate of the descaling water in the descaling device (not shown) installed upstream of the cross rolling mill 10, it is possible to reduce the coefficient of friction between the work rolls 11, 12 and the rolled sheet S. By applying this principle, the difference Δμ between the upper and lower friction coefficients between the work rolls 11, 12 and the rolled sheet S can be BT Just change the following.

[0059] Based on this information, the control device 100 generates control information, from the amount of meandering of the rolled sheet S measured by the meandering meter 20, such as the amount of lubricant to be supplied, the position where the concentration is changed and the amount of lubricant to be supplied and the concentration after the change, the position and amount of grinding for the surfaces of the work rolls 11, 12, or the descaling conditions for the rolled sheet S. Then, the control device 100 outputs the control information to the lubricant supply devices 31, 32, the roll grinding device or the descaling device, and calculates the difference Δμ between the upper and lower friction coefficients. BT These devices are driven to adjust the

[0060] At this time, it is preferable to obtain in advance the relationship between the amount of lubricant supplied, the concentration, the surface roughness of the work rolls 11 and 12, or the descaling conditions, and the amount of meandering of the rolled sheet S. However, even if these relationships are unknown, the amount of lubricant supplied, the concentration, the amount of surface grinding of the work rolls 11 and 12, or the descaling conditions may be adjusted with reference to the amount of meandering of the rolled sheet S measured by the meandering meter 20.

[0061] The rolling method for a rolled sheet according to this embodiment has been described above. According to this embodiment, the difference Δμ between the left and right friction coefficients between the work rolls 11, 12 and the rolled sheet S is DW Based on the amount of meandering of the rolled sheet S caused by the above, the difference Δμ in the coefficient of friction between the work rolls 11, 12 and the rolled sheet S is BT This adjusts the difference in the friction coefficient between the left and right, Δμ, which inevitably changes over time. DW The meandering of the rolled sheet caused by the above is controlled by the difference in the friction coefficient between the top and bottom, Δμ BTThis can be resolved by adjusting the above, thereby improving the flexibility of rolling operations.

[0062] In the above explanation, the amount of meandering of the rolled sheet S was measured at the exit side of the cross rolling mill 10 (S10), but the present invention is not limited to this example, and the amount of meandering of the rolled sheet S may also be measured at the entry side of the cross rolling mill 10. In this case, if the rolled sheet S is meandering toward the drive side of the rolling mill at the entry side of the rolling mill, at least one of adjustments to increase the coefficient of friction between the bottom work roll 12 and the rolled sheet S or adjustments to decrease the coefficient of friction between the top work roll 11 and the rolled sheet S is performed. On the other hand, if the rolled sheet S is meandering toward the work side of the rolling mill at the entry side of the rolling mill, at least one of adjustments to increase the coefficient of friction between the top work roll 11 and the rolled sheet S or adjustments to decrease the coefficient of friction between the bottom work roll 12 and the rolled sheet S may be performed.

[0063] Furthermore, in the above explanation, the cross rolling mill 10 is a pair cross rolling mill, and as shown in FIG. 8, the pair cross rolling mill has work rolls 11, 12 crossed so that on the drive side of the rolling mill the top work roll barrel is located on the exit side of the rolling mill relative to the bottom work roll barrel, and on the working side of the rolling mill the top work roll barrel is located on the entry side of the rolling mill relative to the bottom work roll barrel. However, the present invention is not limited to this example.

[0064] For example, if the work rolls 11, 12 of the pair cross rolling mill are crossed so that the upper work roll barrel is located on the entry side of the rolling mill relative to the lower work roll barrel on the drive side of the rolling mill, and the upper work roll barrel is located on the exit side of the rolling mill relative to the lower work roll barrel on the work side of the rolling mill, the direction of travel of the rolled sheet S due to the difference in the upper and lower friction coefficients will be opposite to that shown in Figure 5. That is, if the upper friction coefficient μ Top is the lower friction coefficient μ Bot If the lower friction coefficient μ is greater than 1, the rolled sheet S will snake toward the drive side (DS) at the exit side of the cross rolling mill 10. On the other hand, if the lower friction coefficient μ Bot is the upper friction coefficient μ TopIf the rolling speed is larger than 1 / 2, the sheet S to be rolled will snake toward the work side (WS) at the exit side of the cross rolling mill 10.

[0065] Therefore, in such an arrangement of the work rolls 11, 12, when the rolled sheet S meanders toward the work side (WS) at the exit side of the cross rolling mill 10, the control device 100 calculates the upper friction coefficient μ Top is the lower friction coefficient μ Bot (i.e., the upper friction coefficient μ Top > Lower friction coefficient μ Bot ) the lower friction coefficient μ Bot Adjustment to reduce the upper friction coefficient μ Top On the other hand, when the rolled sheet S meanders toward the drive side (DS) at the delivery side of the cross rolling mill 10, the control device 100 adjusts the lower friction coefficient μ Bot is the upper friction coefficient μ Top (i.e., the lower friction coefficient μ Bot >Upper friction coefficient μ Top ) the lower friction coefficient μ Bot Adjustment to increase the upper friction coefficient μ Top At least one of the following adjustments is performed:

[0066] In addition, when the rolled sheet S meanders toward the work side (WS) at the inlet side of the cross rolling mill 10, the control device 100 calculates the lower friction coefficient μ Bot is the upper friction coefficient μ Top (i.e., the lower friction coefficient μ Bot >Upper friction coefficient μ Top ) the lower friction coefficient μ Bot Adjustment to increase the upper friction coefficient μ Top On the other hand, when the rolled sheet S meanders toward the drive side (DS) at the inlet side of the cross rolling mill 10, the control device 100 adjusts the upper friction coefficient μ Top is the lower friction coefficient μ Bot (i.e., the upper friction coefficient μ Top > Lower friction coefficient μBot ) the lower friction coefficient μ Bot Adjustment to reduce the upper friction coefficient μ Top In this way, meandering caused by the difference in the coefficient of friction between the left and right sides during rolling of the rolled sheet S can be offset by meandering caused by the difference in the coefficient of friction between the top and bottom, thereby suppressing meandering.

[0067] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0068] For example, in the above embodiment, a pair cross rolling mill has been described as an example of the cross rolling mill 10, but the present invention is not limited to such an example. For example, the cross rolling mill 10 may be a work roll monocross rolling mill. [Explanation of symbols]

[0069] 1. Rolling equipment 10 Cross Rolling Mill 11 Upper work roll 12 Lower work roll 20 Meandering meter 31, 32 Lubricant supply device 100 control device S Rolled plate

Claims

1. In cross rolling, a rolling mill is provided with a pair of work rolls crossed in the rolling plane to roll a plate to be rolled, measuring the meandering amount of the rolled sheet at least at either the entry side or the exit side of the rolling mill; A rolling method for a rolled plate, comprising adjusting a difference in the coefficient of friction between the work roll and the rolled plate on the basis of the amount of meandering of the rolled plate.

2. When the work rolls cross each other so that on the drive side of the rolling mill the upper work roll barrel is located on the exit side of the rolling mill relative to the lower work roll barrel, and on the work side of the rolling mill the upper work roll barrel is located on the entry side of the rolling mill relative to the lower work roll barrel, When the rolled sheet meanders toward the drive side of the rolling mill at the delivery side of the rolling mill, at least one of adjustments is made to increase the coefficient of friction between the top work roll and the rolled sheet, or adjustments are made to decrease the coefficient of friction between the bottom work roll and the rolled sheet, 2. The method for rolling a rolled plate according to claim 1, wherein, when the rolled plate meanders toward the work side of the rolling mill at the delivery side of the rolling mill, at least one of an adjustment to increase the coefficient of friction between the lower work roll and the rolled plate or an adjustment to decrease the coefficient of friction between the upper work roll and the rolled plate is carried out.

3. When the work rolls cross each other so that on the drive side of the rolling mill the upper work roll barrel is located on the exit side of the rolling mill relative to the lower work roll barrel, and on the work side of the rolling mill the upper work roll barrel is located on the entry side of the rolling mill relative to the lower work roll barrel, When the rolled sheet meanders toward the drive side of the rolling mill at the inlet side of the rolling mill, at least one of adjustments is made to increase the coefficient of friction between the bottom work roll and the rolled sheet, or adjustments are made to decrease the coefficient of friction between the top work roll and the rolled sheet, 2. The method for rolling a rolled plate according to claim 1, wherein, when the rolled plate meanders toward the work side of the rolling mill at the entry side of the rolling mill, at least one of an adjustment to increase the coefficient of friction between the top work roll and the rolled plate or an adjustment to decrease the coefficient of friction between the bottom work roll and the rolled plate is carried out.

4. When the work rolls cross each other so that on the drive side of the rolling mill the upper work roll barrel is located on the entry side of the rolling mill relative to the lower work roll barrel, and on the work side of the rolling mill the upper work roll barrel is located on the exit side of the rolling mill relative to the lower work roll barrel, When the rolled sheet meanders toward the drive side of the rolling mill at the delivery side of the rolling mill, at least one of adjustments is made to increase the coefficient of friction between the bottom work roll and the rolled sheet, or adjustments are made to decrease the coefficient of friction between the top work roll and the rolled sheet, 2. The method for rolling a rolled plate according to claim 1, wherein, when the rolled plate meanders toward the work side of the rolling mill at the delivery side of the rolling mill, at least one of an adjustment to increase the coefficient of friction between the upper work roll and the rolled plate or an adjustment to decrease the coefficient of friction between the lower work roll and the rolled plate is carried out.

5. When the work rolls cross each other so that on the drive side of the rolling mill the upper work roll barrel is located on the entry side of the rolling mill relative to the lower work roll barrel, and on the work side of the rolling mill the upper work roll barrel is located on the exit side of the rolling mill relative to the lower work roll barrel, When the rolled sheet meanders toward the drive side of the rolling mill at the inlet side of the rolling mill, at least one of adjustments is made to increase the coefficient of friction between the top work roll and the rolled sheet, or adjustments are made to decrease the coefficient of friction between the bottom work roll and the rolled sheet, 2. The method for rolling a rolled plate according to claim 1, wherein, when the rolled plate meanders toward the work side of the rolling mill at the entry side of the rolling mill, at least one of an adjustment to increase the coefficient of friction between the lower work roll and the rolled plate or an adjustment to decrease the coefficient of friction between the upper work roll and the rolled plate is carried out.

6. 6. The method for rolling a rolled sheet according to claim 1, wherein the difference in the coefficient of friction between the top and bottom work rolls is adjusted by changing the amount of lubricant supplied between the top work roll side and the bottom work roll side.

7. 6. The method for rolling a rolled sheet according to claim 1, wherein the difference in the coefficient of friction between the top and bottom work rolls is adjusted by changing the concentration of the lubricant on the top work roll side and the bottom work roll side.

8. 6. The method for rolling a rolled plate according to claim 1, wherein the difference in the coefficient of friction between the top and bottom work rolls is adjusted by changing at least one of the surface roughness of the work rolls or the surface properties of the rolled plate between the top work roll side and the bottom work roll side.

9. The rolling method for a rolled plate according to any one of claims 1 to 5, wherein the rolling mill that rolls the rolled plate is a pair cross rolling mill.

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