Method of setting reduction leveling

Abstract

To enhance dimensional accuracy after rolling by suppressing occurrence of meandering and camber.SOLUTION: A method of setting reduction leveling in a rolling stand group includes: setting, for a front-stage rolling stand group (a first stand to an M-th stand), a reduction leveling amount of each rolling stand based on at least one of a metal flow in a width direction of material to be rolled or difference in friction coefficient between left and right so that an entry side camber amount of the first stand becomes a target camber amount on an exit side of the M-th stand; calculating, for a rear-stage rolling stand group (the (M + 1) - th stand to the N-th stand), thickness wedge ratio on the exit side of the M-th stand; and setting the reduction leveling amount of each rolling stand based on at least one of the metal flow in the width direction of the material to be rolled or the difference in friction coefficient between left and right so that the thickness wedge ratio on the exit side of each rolling stand of the rear-stage rolling stand group becomes the thickness wedge ratio on the exit side of the M-th stand.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for setting roll leveling for a rolling stand group having a plurality of rolling stands. [Background technology]

[0002] One of the important challenges in rolling operations for rolling materials such as metal plates is to equalize the elongation rate of the material on the work side and the drive side. If the elongation rate of the material is uneven on the work side and the drive side, it can cause threading problems due to meandering of the material, or poor shape due to camber. To equalize the elongation rate of the material on the work side and the drive side, the difference between the reduction position on the work side and the reduction position on the drive side of the rolling mill, i.e., leveling, is corrected.

[0003] For example, Patent Document 1 discloses a method for setting roll leveling in which the camber amount and thickness wedge amount of the rolled material at the entry side of a tandem plate rolling mill are measured or estimated, and a roll leveling amount is set based on these and the rolling schedule of the rolling mill. In this roll leveling setting method, in a group of one or more front-stage rolling mills including a first rolling mill of the tandem plate rolling mill, a roll leveling amount is set for each rolling mill so as to correct the mill entry camber amount to a target camber amount at the exit side of the front-stage rolling mill group, a thickness wedge ratio at the exit side of the front-stage rolling mill group is predicted based on the mill entry thickness wedge amount, the rolling schedule of the front-stage rolling mill group, and a roll leveling setting value, and in a group of rear-stage rolling mills following the front-stage rolling mill group, a roll leveling amount is set for each rolling mill so that the thickness wedge ratio at the exit side of each rolling mill is equal to the thickness wedge ratio at the exit side of the front-stage rolling mill group. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-126813 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the method described in Patent Document 1, when the influence of metal flow in the width direction due to rolling, the influence of a difference in friction coefficient between the left and right sides, etc. cannot be ignored, an error occurs between the actual camber amount and the target camber amount at the delivery side of the front-stage rolling mill group, and this has become apparent, resulting in an increase in strip threading troubles and shape defects.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for setting roll leveling that can suppress the occurrence of meandering or camber and improve the dimensional accuracy after rolling, taking into consideration the influence of metal flow in the width direction and the influence of the difference in friction coefficient between the left and right sides. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, according to one aspect of the present invention, there is provided a method for setting roll gap leveling in a rolling stand group having a plurality of rolling stands, the method comprising the steps of: determining a roll gap leveling amount S of each rolling stand in a front-stage rolling stand group (first stand to Mth stand) including at least a first stand installed on the most upstream side of the rolling stand group; df i:1~M and a step of setting the front-stage roll reduction leveling amount S for each rolling stand in the rear-stage rolling stand group (the M+1st stand to the Nth stand) consisting of the rolling stands installed downstream of the front-stage rolling stand group. df i:M+1~N and a step of setting a rear-stage reduction leveling amount in which the inlet camber amount κ of the first stand is set. 0 is the target camber amount κ at the exit of stand M aim The amount of roll reduction leveling S of each rolling stand of the front-stage rolling stand group is determined based on at least one of the metal flow in the width direction of the rolled material or the difference in the friction coefficient between the rolled material and the roll on the work side and the drive side. df i:1~MIn the step of setting the leveling amount for the rear reduction, the entry thickness wedge amount h df 0 and the rolling schedule and rolling leveling amount S of the front-stage rolling stands. df i:1~M Based on this, the thickness wedge ratio ψ at the outlet of the Mth stand M and the strip thickness wedge ratio ψ on the delivery side of each rolling stand in the rear-stage rolling stand group is calculated. i:M+1~N is the thickness wedge ratio ψ at the outlet of stand M M Based on at least one of the metal flow in the width direction of the rolled material or the difference between the left and right friction coefficients, the roll reduction leveling amount S of each rolling stand of the rear rolling stand group is df i:M+1~N A method for setting a leveling pressure is provided.

[0008] When setting the amount of reduction leveling based on the metal flow in the width direction of the rolled material, coefficient α, which represents the ratio of the actual camber curvature change to the theoretically calculated value of the camber curvature change, may be calculated by the following formula (A) using the projected contact arc length L of the rolled material, the entry thickness H, constants A and B.

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[0009] Strip thickness wedge ratio ψ at the delivery side of the i-th stand of the front-stage rolling stand group i:1~M The absolute value of the thickness wedge ratio ψ at the entry side of the ith stand i-1 If the absolute value of ψ is larger than the value of ψ, the thickness wedge ratio ψ at the delivery side of the i-th stand i is the thickness wedge ratio ψ at the entrance of the i-th stand i-1 The rolling leveling amount of the ith stand may be set so as to coincide with

[0010] Target camber amount κ aim may be set based on rolling performance data up to the previous material.

[0011] The difference in thickness wedge ratio between the entry and delivery sides of the i-th stand in the front-stage rolling stand group is called the thickness wedge ratio change Δψ. i:1~M The absolute value of the upper limit value Δψ of the preset thickness wedge ratio change i(Limit) The leveling amount S of the i-th stand is set as follows: df i:1~M may be set.

[0012] Target camber amount κ aim or the upper limit of the thickness wedge ratio change Δψ Limit At least one of the above may be set based on rolling performance data up to the previous material. [Effects of the Invention]

[0013] As described above, according to the present invention, the influence of metal flow in the width direction and the influence of the difference in friction coefficient between the left and right sides are taken into consideration, and the occurrence of meandering or camber can be suppressed, thereby improving the dimensional accuracy after rolling. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is an explanatory diagram showing an example of the configuration of a tandem rolling mill equipped with a plurality of rolling stands according to an embodiment of the present invention. FIG. [Figure 2] 4 is a flowchart showing a method for setting a roll-down level according to the embodiment; [Figure 3] 1 is a graph showing an example of the relationship between the projected contact arc length L of the rolled material onto the roll and the ratio of the actual camber curvature change to the theoretically calculated value of the camber curvature change when the inlet thickness H of the rolled material and the rolling reduction are changed. [Figure 4] 4 is a graph showing the relationship between the entry thickness H of the rolled material and the magnitude of the proportionality coefficient (-Δα / ΔL), obtained from the results of FIG. 3. [Figure 5] FIG. 2 is an explanatory diagram showing an example of a method for measuring a friction coefficient. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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.

[0016] [1. Composition of rolling stands] First, a schematic configuration of a rolling stand group according to an 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 a tandem rolling mill equipped with a plurality of rolling stands according to this embodiment.

[0017] As shown in Figure 1, a tandem rolling mill 10 is an apparatus that rolls a material S to be rolled to a predetermined thickness by passing it through multiple (N; N is an integer of 2 or greater) rolling stands. The tandem rolling mill 10 shown in Figure 1 is composed of seven rolling stands F1 to F7 arranged along the rolling direction, with the first stand F1 being the rolling stand most upstream in the rolling direction of the material S. Each of the rolling stands F1 to F7 is, for example, a four-high rolling mill equipped with a pair of work rolls 1, 2 and a pair of backup rolls 3, 4 that support the work rolls 1, 2. The reduction position of each of the rolling stands F1 to F7 is adjusted by a reduction device 40.

[0018] At the entrance side of the tandem rolling mill 10, the camber amount (curvature κ 0 ) and the thickness wedge amount (left and right thickness difference h df 0 ) are installed. The measured values ​​of the camber measuring device 20 and the thickness distribution measuring device 30 are output to the calculation device 50. The calculation device 50 calculates the roll reduction leveling setting value (S df i Before rolling is started in each of the rolling stands F1 to F7, the calculation device 50 outputs the calculated roll leveling set value to the roll reduction device 40, causing it to adjust the roll reduction position.

[0019] [2. Rolling leveling method] A method for setting roll gap leveling for a rolling stand group having a plurality of rolling stands will be described with reference to Fig. 2. Fig. 2 is a flowchart showing a method for setting roll gap leveling according to this embodiment. Below, as an example, roll gap leveling setting for the tandem rolling mill 10 shown in Fig. 1 will be described.

[0020] (S10: Obtaining the entry camber amount and entry plate thickness wedge amount) In the method for setting the roll gap leveling according to this embodiment, as shown in FIG. 2, first, the camber amount on the entry side of the first stand of the tandem rolling mill 10 ("entry camber amount κ 0 ") and thickness wedge amount ("entry thickness wedge amount h df 0 ") is measured or estimated (S10). 0 is expressed by the camber curvature and can be detected by the camber measuring device 20 shown in Figure 1. df 0 represents the difference in thickness in the width direction of the rolled material S (i.e., the difference in thickness between the left and right sides), and can be measured by the thickness distribution measuring instrument 30 shown in FIG. 1. Alternatively, the entry camber amount κ 0 and entry thickness wedge amount h df 0 The entry camber amount κ may be estimated based on the rolling performance of a rolling mill installed upstream of the tandem rolling mill 10 in the rolling direction. 0 and entry thickness wedge amount h df 0 is output to the arithmetic unit 50.

[0021] (S20: Obtaining the reduction schedule) Next, the arithmetic device 50 acquires the reduction schedule for each rolling stand F1 to F7 of the tandem rolling mill 10 (S20). In the reduction schedule for each rolling stand F1 to F7, for example, the inlet / outlet (average) plate thickness H / h, plate width b, predicted rolling load P, etc. are set. The arithmetic device 50 acquires the various values ​​set in the reduction schedule.

[0022] (S30: Get target camber amount) The calculation device 50 also calculates a target camber amount κ on the exit side of the Mth stand, which is specified in advance. aim is acquired (S30). Here, of the multiple rolling stands constituting the tandem rolling mill 10, one or more rolling stands arranged on the upstream side in the rolling direction are referred to as a front rolling stand group, and one or more rolling stands arranged on the downstream side in the rolling direction are referred to as a rear rolling stand group. The front rolling stand group and the rear rolling stand group can be set arbitrarily. In the following, in a tandem rolling mill consisting of N rolling stands, the first to Mth stands are referred to as a front rolling stand group, and the M+1th to Nth stands are referred to as a rear rolling stand group (M is a positive integer). When M=1, the first stand is referred to as a front rolling stand group, and the second to Nth stands are referred to as a rear rolling stand group.

[0023] Target camber amount κ at the exit of stand M aim is set in advance based on the rolling performance data up to the previous material. The calculation device 50 calculates the set target camber amount κ on the outlet side of the Mth stand. aim Get.

[0024] (S40: Setting of rolling leveling amount (pre-rolling stands)) Then, the calculation device 50 calculates the entry camber amount κ of the first stand using the various values ​​acquired in steps S10 to S30. 0 is the target camber amount κ at the exit of stand M aim The amount of reduction leveling S of each rolling stand in the front-stage rolling stand group is df i:1~M is calculated and set (S40). df i:1~M In the calculation of , at least one of the width direction metal flow and the difference between the left and right friction coefficients is taken into consideration. df i:1~M may be calculated, for example, by the following procedure.

[0025] First, the camber (curvature) change Δκ in each rolling stand is calculated using the following formula (1). i:1~M Calculate.

[0026]

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[0027] The camber (curvature) change Δκ at each rolling stand calculated using the above formula (1) i From the above, the rolling leveling amount S of each rolling stand is calculated using the following formula (2). df i Calculate.

[0028]

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[0029] where σ i-1 is the entry tension of the ith stand, σ i is the tension at the exit of the i-th stand, P i is the predicted rolling load, D (i) is the dimension parameter of the ith stand, K (i) is the stiffness parameter of the ith stand. h df i-1 is the thickness wedge amount at the entrance of the i-th stand, and the thickness wedge ratio ψ for the i-1-th stand is obtained by the formula (4) described later. i-1 Plate thickness h i-1 It is evaluated by multiplying α i is a coefficient that takes into account the metal flow in the width direction of the rolled material (0<α≦1), μ W i is the friction coefficient on the working side, μ D i is the friction coefficient on the driving side.

[0030] In the method for setting the roll gap leveling according to this embodiment, as shown in the above formula (2), the roll gap leveling amount S df iWhen calculating, the influence of the widthwise metal flow of the rolled material and the influence of the difference in the left-right friction coefficient between the work side and the drive side are taken into consideration. If significant widthwise metal flow of the rolled material occurs, part of the change in the thickness wedge ratio is absorbed by the widthwise metal flow, so the change in camber curvature will be smaller than the theoretically calculated value. Therefore, if the influence of widthwise metal flow is not taken into consideration, it may not be possible to obtain a sufficient camber correction effect in the front-stage rolling stands. Furthermore, if there is a difference in the left-right friction coefficient between the work side and the drive side, meandering or camber without a change in the thickness wedge ratio may occur. Therefore, the roll reduction leveling amount S is calculated by taking into consideration the influence of widthwise metal flow of the rolled material and the influence of the difference in the left-right friction coefficient between the work side and the drive side. df i By calculating this, the camber is properly corrected and meandering is suppressed.

[0031] The influence of metal flow in the width direction of the rolled material is expressed by coefficient α i This can be taken into account by including it as a parameter in equation (2) above. The coefficient α represents the ratio of the actual camber curvature change amount, which is mitigated by the influence of metal flow in the width direction, to the theoretically calculated value of the camber curvature change. If there is no influence of metal flow in the width direction, the coefficient α should be set to 1, and a value between 0 and α should be set to 1 depending on the influence of metal flow in the width direction.

[0032] Here, the value of coefficient α under each rolling condition was evaluated by FEM analysis. The results are shown in Figures 3 and 4. Figure 3 is a graph showing an example of the relationship between the projected contact arc length L of the rolled material and the ratio of the actual camber curvature change to the theoretically calculated value of camber curvature change when the entry thickness H of the rolled material and the reduction ratio are changed. Figure 4 is a graph showing the relationship between the entry thickness H of the rolled material and the magnitude of the proportionality coefficient (-Δα / ΔL) obtained from the results of Figure 3.

[0033] In the FEM analysis, a leveling reduction amount that would result in a 200μm delivery wedge when there was no difference in the left and right friction coefficient was added as a disturbance. The friction coefficients on the work side and the drive side were both set to 0.3. The entry thickness H of the rolled material was set to 60mm and 40mm, assuming rolling in the front rolling stand, and 20mm and 5mm, assuming rolling in the rear rolling stand.

[0034] First, the projected contact arc length L was changed by changing the reduction ratio for each entry thickness H of the rolled material. As a result, as shown in Figure 3, it was found that coefficient α, which represents the ratio of the actual camber curvature change to the theoretically calculated value, correlates with the projected contact arc length L and the entry thickness H. Furthermore, when an approximation line representing the relationship between the projected contact arc length L and coefficient α is obtained for each entry thickness H of the rolled material, it is found that the magnitude of the slope of the approximation line (-Δα / ΔL) changes depending on the entry thickness H of the rolled material. It is found that the change in the magnitude of the slope of the approximation line (-Δα / ΔL) due to changes in the entry thickness H of the rolled material can be approximated by a power, as shown in Figure 4. From these results, coefficient α can be found using the following equation (3).

[0035]

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[0036] Here, A and B are constants. The constants A and B may be values ​​obtained from an approximation curve of the FEM analysis results as shown in Fig. 4, for example, or may be determined by identifying them from the measured values ​​of the change in camber curvature when actual rolling is performed while changing the entry thickness H or the reduction ratio.

[0037] In addition, the influence of the difference in the friction coefficient between the left and right sides is W i and the friction coefficient μ on the drive side D i This can be taken into account by including it in the parameters of the above formula (2). Note that the difference in the left and right friction coefficients Δμ is the friction coefficient μ W i and the friction coefficient μ on the driving side D iand the difference (Δμ=μ W i -μ D i ).

[0038] The friction coefficient μ between the work roll and the material being rolled is the friction coefficient on the work side (material-roll friction coefficient). W i and the friction coefficient μ on the drive side D i can be obtained using a known technique (for example, Japanese Patent Application Laid-Open No. 4-284909). In this method, in order to obtain the coefficient of friction between the material and the roll, the roll stand on the upstream side of the tandem rolling mill receives a load cell ON signal from the roll stand, and calculates the delivery speed V0 and the roll peripheral speed V1 as shown in FIG. R Measure the exit speed V0 and roll peripheral speed V R The forward slip ratio is obtained from the ratio of the exit speed V0 to the roll speed. The exit speed V0 can be measured by an exit speed meter 61 arranged on the exit side of the rolling stand. Then, the coefficient of friction between the material S to be rolled and the roll is calculated from the forward slip ratio based on the measured value and the actual value of the rolling load P measured by the load meter 63. In this case, if at least one exit speed meter 61 is installed on each of the work side and the drive side, the coefficient of friction between the material S and the roll can be calculated on both the work side and the drive side.

[0039] It is also generally known that the coefficient of friction between a material and a roll depends on the surface roughness of the object. Therefore, for example, before assembling the rolls, the relationship between the surface roughness of the work rolls and the rolled material and the coefficient of friction between the material and the roll is determined in advance, and this relationship is obtained as a table. A table showing the relationship between the surface roughness of the work rolls and the rolled material and the coefficient of friction between the material and the roll can be obtained, for example, by preparing test pieces made of the same material as the surfaces of the work rolls and the rolled material but with different surface roughnesses, and measuring the coefficient of friction using a friction and wear tester or the like.

[0040] Then, after the rolls are assembled, the surface roughness of the work rolls and the rolled material can be measured before rolling begins, and the coefficient of friction between the material and the roll can be estimated by referring to a previously obtained table. The surface roughness of the work rolls can be measured using a work roll surface roughness meter 65 installed on the exit side of the rolling stand, as shown in FIG. 5. The surface roughness of the rolled material can be measured using a rolled material surface roughness meter 67 installed on the entry side of the rolling stand, as shown in FIG. 5. In this case, if at least one work roll surface roughness meter 65 and one rolled material surface roughness meter 67 are installed on the work side and the drive side, the coefficient of friction between the material and the roll can be calculated for the work side and the drive side, respectively.

[0041] In the above formula (2), both the influence of the metal flow in the width direction of the rolled material and the influence of the difference in the friction coefficient between the work side and the drive side are taken into consideration, but the camber correction effect can be obtained by taking at least one of these into consideration. For example, in cases where lubrication is uniform in the width direction and it can be considered that there is no difference in the friction coefficient between the left and right, or in cases where no delivery speed meter or roughness meter is installed on the rolling stand, the reduction leveling amount S can be calculated by taking only the influence of the metal flow in the width direction of the rolled material. df i Furthermore, when there is a difference in the friction coefficient between the left and right, the rolling leveling amount S can be calculated to compensate for the camber curvature change caused by the difference in the friction coefficient between the left and right, taking into consideration the influence of the metal flow in the width direction of the rolled material as well as the friction coefficient on the work side and the friction coefficient on the drive side. df i may be calculated.

[0042] Table 1 shows an example of the value of coefficient α obtained from the results shown in Figure 3. Table 1 shows the values ​​of coefficient α when the entry plate thickness H is 20 mm, 40 mm, and 60 mm, and the reduction ratio r, which correlates with the projected contact arc length L, is set to 0.1, 0.3, and 0.5. When actually performing rolling, coefficient α may be set from the above formula (3), but coefficient α, which represents the influence of metal flow, may also be set for each rolling condition (entry plate thickness, reduction ratio) based on a table such as that shown in Table 1 below. Alternatively, for simplicity, the average value within the range of conditions (for example, the average value (0.77) of the nine points shown in Table 1) may be set as coefficient α, and this may be set as a fixed value regardless of the rolling conditions.

[0043] [Table 1]

[0044] Table 2 shows the difference in camber curvature change between the case where there is a difference in the friction coefficient between the left and right sides of 0.01 and the case where there is no difference in the friction coefficient between the left and right sides under the same rolling conditions as in Figure 3 [×10 -4 / m]. Table 2 also shows that the camber curvature change changes depending on whether there is a difference in the friction coefficient between the left and right sides. When actually rolling, the roll leveling amount S for each rolling stand is calculated based on the estimated result of the difference in the friction coefficient between the left and right sides, as shown in Table 2 below. df It should be noted that Table 2 shows the results when a leveling amount that results in an exit wedge of 200 μm is applied as a disturbance, but the camber due to the difference in friction coefficient between the left and right does not depend on the change in the wedge ratio, and even if the exit wedge is set to a different value, the difference in the camber curvature change shown in Table 2 does not change significantly. Therefore, the leveling amount S for each rolling stand can be calculated based on the results calculated by setting the exit wedge to a different value (for example, no exit wedge). df may be set.

[0045] [Table 2]

[0046] From the above, for example, when the entry thickness H=20 mm and the reduction ratio r=0.1, the coefficient α can be set to 0.84 from Table 1. Also, for a certain change in the wedge ratio, the theoretical value of the change in camber curvature Δκ can be calculated from Table 2. T Then, the camber curvature change is Δκ T ×α-0.41×10 -4 [ / m]. Based on this, you can calculate the required amount of leveling.

[0047] (S50, S60: Setting of rolling leveling amount (rear rolling stands)) In step S40, the roll leveling amount S of each rolling stand of the front-stage rolling stand group is calculated. df i:1~M When the calculation is performed, the calculation device 50 calculates the roll leveling amount S of each rolling stand for the rear-stage rolling stand group consisting of the rolling stands installed downstream of the front-stage rolling stand group. df i:M+1~N Calculate.

[0048] First, the calculation device 50 calculates the inlet thickness wedge amount h of the first stand. df 0 and the rolling schedule and rolling leveling amount S of the front-stage rolling stands. df i:1~M Based on this, the thickness wedge ratio ψ at the outlet of the Mth stand M (S50) The thickness wedge ratio ψ at the outlet of the Mth stand is calculated. M can be calculated for the final rolling stand (i=M) of the group of front-stage rolling stands using the following formula (4).

[0049]

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[0050] The wedge ratio on the delivery side relative to the leveling amount changes depending on the metal flow in the width direction of the rolled material. On the other hand, the difference in the friction coefficient between the left and right sides usually does not change with the wedge ratio. Therefore, in the above formula (4), the friction coefficient μ on the work side W i and the friction coefficient μ on the drive sideD i In addition, if the difference in the friction coefficient between the left and right sides has an effect that significantly changes the rolling load between the left and right sides, the friction coefficient μ W i and the friction coefficient μ on the drive side D i may be considered.

[0051] The calculation device 50 calculates the thickness wedge ratio ψ at the outlet of the Mth stand. M Substituting this into the following equation (5), the reduction leveling amount S of the rear rolling stands is obtained. df i:M+1~N is calculated (S60).

[0052]

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[0053] From the above formula (5), the strip thickness wedge ratio ψ at the outlet of the Mth stand is M is maintained in the downstream rear rolling stands (i=M+1 to N) (i.e., ψ i:M+1~N =ψ M The amount of reduction leveling S of the rear rolling stands to df i:M+1~N is calculated.

[0054] As shown in the above formula (5), the rolling stand leveling amount S df iWhen calculating , the influence of metal flow in the width direction of the rolled material and the influence of the difference in left-right friction coefficient between the work side and the drive side are taken into consideration. In the technology described in Patent Document 1 above, the aim was to keep the thickness wedge ratio constant in the rear-stage rolling stands so that the camber corrected in the front-stage rolling stands would not reoccur in the rear-stage rolling stands. However, it has been found that, for example, in cases where there is a difference in the left-right friction coefficient in the rear-stage rolling stands, camber will reoccur even if the aim is to keep the thickness wedge ratio constant. Therefore, in the method for setting roll gap leveling according to this embodiment, the influence of metal flow in the width direction of the rolled material in the rear-stage rolling stands and the influence of the difference in left-right friction coefficient are taken into consideration, and a roll gap leveling amount S is set to allow for changes in the wedge ratio and to prevent camber from reoccurring in the rear-stage rolling stands. df i:M+1~N Calculate.

[0055] (S70: Press down position adjustment) Then, the calculation device 50 calculates the roll leveling amount S of each rolling stand of the tandem rolling mill 10 calculated in steps S40 and S60. df i:1~N The screw down device 40 outputs the leveling amount S df i:1~N Based on this, the pressing position is adjusted (S70).

[0056] The method for setting roll gap leveling according to this embodiment has been described above. According to this embodiment, for the front-stage rolling stands, the entry camber amount κ of the first stand is determined by taking into consideration at least one of the width direction metal flow of the rolled material and the difference between the left and right friction coefficients. 0 is the target camber amount κ at the exit of stand M aim The amount of reduction leveling S of each rolling stand is df i:1~M For the rear-stage rolling stand group, the strip thickness wedge ratio ψ on the delivery side of each rolling stand is set. i:M+1~N is the thickness wedge ratio ψ at the outlet of stand M MThe rolling leveling amount S is determined by taking into consideration at least one of the width direction metal flow of the rolled material or the difference between the left and right friction coefficients. df i:M+1~N This makes it possible to suppress the occurrence of meandering or camber and improve the dimensional accuracy after rolling.

[0057] As mentioned above, the front rolling stand group may be a group of one or more rolling stands including at least the first stand installed at the most upstream of the tandem rolling mill. For example, only the first stand may be the front rolling stand group, and the second stand to the final stand may be the rear rolling stand group. In this case, the following simplified formulas (1'), (2'), (4'), and (5') may be used instead of the above formulas (1), (2), (4), and (5).

[0058]

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[0059] where λ i is the extension at stand i (=H i / h i ), m i is the plasticity coefficient, K D 1 is the parallel stiffness, a i is the distance between the supports of the screw down device 40.

[0060] Furthermore, the target camber amount κ of the Mth stand set in step S30 described above aim may be set to zero or a small value that does not cause practical problems in terms of strip threading, product dimensional accuracy, winding shape accuracy, etc. In the case where it is desired to correct the camber shape as much as possible and not to worsen the strip thickness wedge ratio in terms of strip thickness dimensional accuracy, for example, the delivery strip thickness wedge ratio ψ of the ith stand calculated by the above-mentioned formula (4) can be set to i and the entry thickness wedge ratio ψ of the i-th stand i-1 Compared with [Outlet thickness wedge ratio ψ i Absolute value of entry thickness wedge ratio ψ i-1, for example, ψ on the right side of the above formula (5) M ψ i-1 Instead of the above, the rolling leveling amount S of the rolling stand (i-th stand) df i can be calculated.

[0061] Furthermore, when excessive meandering and camber due to excessive changes in the thickness wedge ratio are expected to occur in the front-stage rolling stand group, the upper limit value Δψ of the thickness wedge ratio change allowed in the i-th stand in the front-stage rolling stand group is set to i(Limit) is determined in advance, and the entry thickness wedge ratio ψ of the i-th stand calculated by equation (4) is used. i-1 and delivery thickness wedge ratio ψ i (However, ψ 0 is the measured or estimated entry thickness wedge h of the first stand df 0 is the entry thickness of the first stand h 0 If the absolute value of the difference between the thickness wedge h of the i-th stand and the thickness wedge h of the i-th stand is limited by the following formula (6), df i(Limited) The rolling leveling amount S of the i-th stand is calculated using, for example, the following formula (7). df i Just calculate it.

[0062]

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[0063] Furthermore, in the roll gap leveling setting method according to this embodiment, it is sufficient to perform at least one of setting the roll gap leveling amount for the front-stage rolling stand group in step S40 and setting the roll gap leveling amount for the rear-stage rolling stand group in steps S50 and S60.

[0064] For example, as shown in Figure 3, whether the entry thickness H of the material to be rolled assumed to be rolled in the front rolling stands is 60 mm or the entry thickness H of the material to be rolled assumed to be rolled in the rear rolling stands is 5 mm, the value of coefficient α changes depending on the value of projected contact arc length L. Therefore, even if only one of setting the roll clearance leveling amount for the front rolling stands (S30) and setting the roll clearance leveling amount for the rear rolling stands (S50, S60) is performed, the camber amount can be reduced. Also, for example, if the influence of the difference in friction coefficient is significant only in the front rolling stands due to characteristics unique to the rolling mill, the effect of reducing the camber amount is significant even if only setting the roll clearance leveling amount for the front rolling stands in step S30. [Example]

[0065] For a tandem rolling mill consisting of seven rolling stands as shown in Figure 1, the roll gap positions of each rolling stand were set, and the amount of camber that occurred during rolling of a steel plate was measured. In Examples 1 to 3, the roll gap positions were set based on the roll gap leveling setting method according to one embodiment of the present invention as shown in Figure 2. In Example 1, the influence of metal flow in the width direction was taken into consideration, in Example 2 the influence of the difference in friction coefficient between the left and right sides was taken into consideration, and in Example 3 the influence of metal flow in the width direction and the influence of the difference in friction coefficient between the left and right sides were taken into consideration. In Comparative Example 1, the roll gap positions were set based on the roll gap leveling setting method of Patent Document 1 mentioned above. That is, in Comparative Example 1, the roll gap positions were set without taking into consideration the influence of metal flow in the width direction and the influence of the difference in friction coefficient between the left and right sides.

[0066] In this verification, the first rolling stand was the only stand in the front-stage rolling stand group, and stands 2 to 7 were the rear-stage rolling stand group. The target camber amount on the delivery side of the first stand was set to zero. The entry thickness of the first stand was 30 to 50 mm, and a total of 100 steel plates were rolled.

[0067] The average amount of camber that occurred (actual camber amount) is shown in Table 3. The actual camber amounts shown in Table 3 are shown as relative values ​​when the average value of the amount of camber that occurred in Comparative Example 1 is set to 100. Furthermore, for Examples 1 and 3, the average value of the coefficient α that represents the influence of metal flow set in the front-stage rolling stand group (i.e., the first stand) is shown, and for Examples 2 and 3, the average value of the left-right difference Δμ in the coefficient of friction of the front-stage rolling stand group (i.e., the first stand) is shown.

[0068] [Table 3]

[0069] As can be seen from Table 3, the amount of camber was reduced in Examples 1 to 3, which considered at least one of the effects of widthwise metal flow and the effect of the difference in friction coefficient between left and right, compared to Comparative Example 1, which did not consider the effects of widthwise metal flow and the effect of the difference in friction coefficient between left and right. In particular, by considering the effects of widthwise metal flow and the effect of the difference in friction coefficient between left and right, as in Example 3, the amount of camber that occurred could be further reduced. Furthermore, the dimensional accuracy of the product was also significantly improved.

[0070] 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.

[0071] The following configurations are also included in the technical scope of the present disclosure.

[0072] (1) A method for setting roll leveling in a rolling stand group having a plurality of rolling stands, comprising: For the front-stage rolling stand group (1st stand to Mth stand) including at least the 1st stand installed on the most upstream side of the rolling stand group, the roll reduction leveling amount S of each rolling stand df i:1~M a step of setting a leveling amount for the first stage reduction; Regarding the rear-stage rolling stand group (M+1 stand to Nth stand) consisting of rolling stands installed downstream of the front-stage rolling stand group, the roll reduction leveling amount S of each rolling stand is df i:M+1~N a post-press leveling amount setting step for setting the post-press leveling amount; At least one of the following will be implemented: In the step of setting the leveling amount for the first stage reduction, the inlet camber amount κ of the first stand is set. 0 is the target camber amount κ at the exit side of the M stand aim The amount of roll leveling S of each rolling stand of the front-stage rolling stand group is determined based on at least one of the metal flow in the width direction of the rolled material or the difference in the friction coefficient between the rolled material and the roll on the work side and the drive side. df i:1~M Set In the step of setting the leveling amount for the latter stage reduction, The entry thickness wedge amount h of the first stand df 0 and the rolling schedule and rolling leveling amount S of the front-stage rolling stand group. df i:1~M Based on this, the thickness wedge ratio ψ at the outlet of the Mth stand is M Calculate The strip thickness wedge ratio ψ on the delivery side of each rolling stand of the rear-stage rolling stand group i:M+1~N is the thickness wedge ratio ψ at the outlet of the stand M M Based on at least one of the metal flow in the width direction of the rolled material or the difference between the left and right friction coefficients, the roll reduction leveling amount S of each rolling stand of the rear-stage rolling stand group is determined. df i:M+1~N Setting method for pressure leveling.

[0073] (2) The method for setting roll reduction leveling according to (1) above, wherein when setting the roll reduction leveling amount based on the metal flow in the width direction of the rolled material, a coefficient α representing the ratio of the actual camber curvature change amount to the theoretically calculated value of the camber curvature change is calculated by the following formula (A) using the projected contact arc length L of the rolled material, the entry plate thickness H, a constant A, and a constant B.

[0074]

number

[0075] (3) a strip thickness wedge ratio ψ on the outlet side of the ith stand of the front-stage rolling stand group; i:1~M The absolute value of the thickness wedge ratio ψ at the entry side of the i-th stand i-1 If it is greater than the absolute value of The thickness wedge ratio ψ at the outlet of the i-th stand i is the thickness wedge ratio ψ at the entry side of the i-th stand i-1 The method for setting roll reduction leveling according to (1) or (2) above, wherein the roll reduction leveling amount of the i-th stand is set so as to coincide with

[0076] (4) the target camber amount κ aim The method for setting the roll leveling according to any one of the above (1) to (3), wherein the roll leveling is set based on rolling performance data up to the previous material.

[0077] (5) The thickness wedge ratio change Δψ is the difference between the thickness wedge ratios at the entry side and delivery side of the i-th stand of the front-stage rolling stand group. i:1~M The absolute value of the upper limit value Δψ of the preset thickness wedge ratio change i(Limit) The leveling amount S of the i-th stand is set as follows: df i:1~M The method for setting a roll-down leveling according to any one of (1) to (3) above, wherein the roll-down leveling is set.

[0078] (6) the target camber amount κaim or the upper limit value Δψ of the thickness wedge ratio change Limit At least one of the above is set based on rolling performance data up to the previous material. [Explanation of symbols]

[0079] 10 Tandem rolling mill 20 Camber measuring device 30 Plate thickness distribution measuring device 40 Screw down device 50 Arithmetic unit 61 Exit speedometer 63 Load cell 65 Work roll surface roughness meter 67 Rolled material surface roughness meter

Claims

1. A method for setting roll leveling in a rolling stand group having a plurality of rolling stands, comprising: For the front-stage rolling stand group (1st stand to Mth stand) including at least the 1st stand installed on the most upstream side of the rolling stand group, the roll reduction leveling amount S of each rolling stand ｄｆ ｉ：１～Ｍ a step of setting a leveling amount for the first stage reduction; For the rear-stage rolling stand group (M+1 stand to N stand) consisting of rolling stands installed downstream of the front-stage rolling stand group, the roll reduction leveling amount S of each rolling stand is ｄｆ ｉ：Ｍ＋１～Ｎ a post-press leveling amount setting step for setting the post-press leveling amount; At least one of the following will be implemented: In the step of setting the leveling amount for the first stage reduction, the inlet camber amount κ of the first stand is set. ０ is the target camber amount κ at the exit side of the M stand ａｉｍ The amount of reduction leveling S of each rolling stand of the front-stage rolling stand group is determined based on at least one of the metal flow in the width direction of the rolled material or the difference in the friction coefficient between the rolled material and the roll on the work side and the drive side. ｄｆ ｉ：１～Ｍ Set In the step of setting the leveling amount for the latter stage reduction, The inlet thickness wedge amount h of the first stand ｄｆ ０ and the rolling schedule and rolling leveling amount S of the front-stage rolling stand group. ｄｆ ｉ：１～Ｍ Based on this, the thickness wedge ratio ψ on the outlet side of the Mth stand is calculated. Ｍ Calculate The strip thickness wedge ratio ψ on the delivery side of each rolling stand of the rear-stage rolling stand group ｉ：Ｍ＋１～Ｎ is the thickness wedge ratio ψ at the outlet of the Mth stand Ｍ Based on at least one of the metal flow in the width direction of the rolled material or the difference between the left and right friction coefficients, the roll reduction leveling amount S of each rolling stand of the rear-stage rolling stand group is determined. ｄｆ ｉ：Ｍ＋１～Ｎ Setting method for pressure leveling.

2. 2. A method for setting roll gap leveling according to claim 1, wherein, when setting a roll gap leveling amount based on the metal flow in the width direction of the rolled material, a coefficient α representing a ratio of an actual camber curvature change amount to a theoretically calculated value of the camber curvature change is calculated by the following formula (A) using the projected contact arc length L of the rolled material, the entry plate thickness H, a constant A, and a constant B: [Equation 1]

3. a strip thickness wedge ratio ψ on the outlet side of the i-th stand of the front-stage rolling stand group; ｉ：１～Ｍ The absolute value of the thickness wedge ratio ψ at the entry side of the i-th stand ｉ－１ If it is greater than the absolute value of The thickness wedge ratio ψ at the outlet of the i-th stand ｉ is the thickness wedge ratio ψ at the entry side of the i-th stand ｉ－１ 3. The method for setting roll reduction leveling according to claim 1, wherein the roll reduction leveling amount of the i-th stand is set so as to coincide with:

4. the target camber amount κ ａｉｍ The method for setting the roll gap leveling according to claim 1 or 2, wherein the roll gap leveling is set based on rolling performance data up to the previous material.

5. A thickness wedge ratio change Δψ, which is the difference between the thickness wedge ratios at the entry side and delivery side of the i-th stand of the front-stage rolling stand group ｉ：１～Ｍ The absolute value of the upper limit value Δψ of the preset thickness wedge ratio change ｉ（Ｌｉｍｉｔ） The leveling amount S of the i-th stand is set as follows: ｄｆ ｉ：１～Ｍ The method for setting a roll-down leveling according to claim 1 or 2, wherein the roll-down leveling is set.

6. the target camber amount κ ａｉｍ or the upper limit value Δψ of the thickness wedge ratio change Ｌｉｍｉｔ 6. The method for setting a roll gap level according to claim 5, wherein at least one of the above is set based on rolling performance data up to the previous material.

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