Plate thickness control device of rolling mill

Abstract

The movement distance calculation unit calculates the movement distance of the rolling material from the rolling mill. The reel rotation angle calculation unit calculates the rotation angle of a reel provided on at least one of the entry side and the exit side of the rolling mill. The plate thickness deviation calculation unit calculates a plate thickness deviation. The plate thickness deviation input determination unit determines the input timing of the plate thickness deviation on the basis of the movement distance of the rolled material calculated by the movement distance calculation unit and the rotation angle of the reel calculated by the reel rotation angle calculation unit. The plate thickness deviation storage unit adds and stores the plate thickness deviations calculated by the plate thickness deviation calculation unit on the basis of the input timing determined by the plate thickness deviation input determination unit. The plate thickness deviation output determination unit determines the output timing of the plate thickness deviation on the basis of the rotation angle of the reel calculated by the reel rotation angle calculation unit. The operation amount calculation unit reads the integrated value of the plate thickness deviation stored in the plate thickness deviation storage unit on the basis of the output timing determined by the plate thickness deviation output determination unit, and calculates the operation amount of the screw down device of the rolling mill on the basis of the integrated value.

Description

Technical Field

[0001] The present invention relates to a plate thickness control device for a rolling mill, and particularly to a plate thickness control device that is preferably applied to a rolling mill for cold rolling metals and the like. Background Art

[0002] For example, during the rolling process, the gap between the upper and lower working rolls of the rolling mill (hereinafter referred to as "roll gap") is appropriately adjusted by a screw-down device, thereby controlling the plate thickness of the material being rolled to a target plate thickness value (also referred to as product plate thickness, set plate thickness).

[0003] Generally, a reel for winding the rolled material is disposed on at least one of the inlet side and the outlet side of the rolling mill. In such a reel, typically, the rolled material is wound in such a manner that the front end is inserted into the gap of the portion (mandrel) where winding is performed. In this case, due to the bulging of the front end portion of the rolled material, Figure 8 eccentricity of the reel as shown occurs. As a result, each time the reel rotates, a tension variation of the rolled material occurs between the rolling mill and the reel. The tension variation affects the plate thickness on the outlet side of the rolling mill, resulting in a reduction in product quality.

[0004] For example, methods for suppressing the above-mentioned tension variation are proposed in Patent Documents 1 and 2. In Patent Document 1, a tension deviation is stored in an offset register according to the rotation angle of the reel, and a value corresponding to the rotation angle is taken out from the offset register, and based on this, the motor torque of the reel is operated, thereby suppressing the tension variation associated with the eccentricity of the reel. In Patent Document 2, the amount of change in the reel diameter is stored in association with the reel rotation position, and a correction value for the rotation speed of the reel is generated based on the amount of change in the reel diameter, and the tension variation is suppressed by controlling the rotation speed of the reel. In either method, the improvement of the plate thickness accuracy, which is an index of product quality, is achieved by reducing the tension variation caused by the eccentricity of the reel.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Laid-Open No. 11-285730

[0008] Patent Document 2: Japanese Patent Laid-Open No. 2015-36150 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] However, in Patent Document 1, a phase advance element is inserted in consideration of the response delays of the current control system, the tension generation system, and the tension detector. However, since the tension generation system is a physical phenomenon, there are sometimes deviations from the delays inferred by theoretical formulas, and it is not easy to sufficiently suppress tension fluctuations. In Patent Document 2, the rotational speed is corrected based on the amount of change in the reel diameter so that there is no speed difference with the rolling mill. However, the response of the speed control system is generally not very fast, so it may not be possible to sufficiently reduce the tension fluctuations caused by reel eccentricity.

[0011] The present invention has been completed to solve the above problems, and an object thereof is to provide a plate thickness control device for a rolling mill that can reduce the influence of reel eccentricity on the plate thickness on the outlet side of the rolling mill even when tension fluctuations of the rolled material occur due to reel eccentricity caused by winding of the rolled material onto the reel.

[0012] Means for Solving the Problems

[0013] A first aspect relates to a plate thickness control device for a rolling mill. A thickness gauge is provided on the outlet side of the rolling mill. The plate thickness control device includes a moving distance calculation unit, a reel rotation angle calculation unit, a plate thickness deviation calculation unit, a plate thickness deviation input determination unit, a plate thickness deviation storage unit, a plate thickness deviation output determination unit, and an operation amount calculation unit. The moving distance calculation unit calculates the distance that the rolled material moves from the rolling mill after being rolled by the rolling mill. The reel rotation angle calculation unit calculates the rotation angle of at least one of the reels provided on the inlet side and the outlet side of the rolling mill. The plate thickness deviation calculation unit calculates a plate thickness deviation based on the plate thickness measurement value of the rolled material measured by the thickness gauge. The plate thickness deviation input determination unit determines the input timing of the plate thickness deviation based on the moving distance of the rolled material calculated by the moving distance calculation unit and the rotation angle of the reel calculated by the reel rotation angle calculation unit. The plate thickness deviation storage unit adds and stores the plate thickness deviation calculated by the plate thickness deviation calculation unit based on the input timing determined by the plate thickness deviation input determination unit. The plate thickness deviation output determination unit determines the output timing of the plate thickness deviation based on the rotation angle of the reel calculated by the reel rotation angle calculation unit. The operation amount calculation unit reads out the cumulative value of the plate thickness deviation stored in the plate thickness deviation storage unit based on the output timing determined by the plate thickness deviation output determination unit, and calculates the operation amount of the rolling mill's rolling reduction device based on this cumulative value.

[0014] A second aspect further has the following features on the basis of the first aspect. A plate speed meter is provided on the outlet side of the rolling mill. The moving distance calculation unit calculates the distance that the rolled material moves from the rolling mill after being rolled by the rolling mill based on the speed of the rolled material measured by the plate speed meter.

[0015] The third aspect further has the following features based on the first aspect. The sheet thickness deviation input determination unit and the sheet thickness deviation output determination unit are configured to compensate for at least one of the measurement delay caused by the sheet thickness gauge, the delay caused by signal transmission and calculation, and the response delay of the rolling mill's screwdown device, and respectively determine the input timing and the output timing.

[0016] The fourth aspect further has the following features based on the first aspect. The sheet thickness deviation storage unit is configured to multiply the sheet thickness deviation stored in the sheet thickness deviation storage unit by a forgetting coefficient less than 1, and add the sheet thickness deviation calculated by the sheet thickness deviation calculation unit.

[0017] The fifth aspect further has the following features based on the first aspect. The operation amount calculation unit is configured to, when calculating the operation amount of the screwdown device, obtain an adjustment coefficient corresponding to the coil diameter of the rolled material wound on the reel, and use the obtained adjustment coefficient to adjust the operation amount.

[0018] The sixth aspect further has the following features based on any one of the first to fifth aspects. A tension meter is provided on at least one of the inlet side and the outlet side of the rolling mill, and the motor of the reel is controlled so that the tension measured by the tension meter becomes the tension target value. The operation amount calculation unit is configured to calculate a correction amount of the tension target value based on the operation amount of the screwdown device.

[0019] Advantages of the Invention

[0020] According to the first aspect, by establishing a correspondence between the sheet thickness deviation and the rotation angle of the reel, it is possible to extract the periodic sheet thickness variation caused by reel eccentricity. The operation amount of the screwdown device is calculated based on the sheet thickness variation extracted corresponding to the rotation angle of the reel, and the screwdown device with a faster response than the conventional speed control system is operated. Therefore, even if a tension variation of the rolled material occurs due to reel eccentricity caused by winding of the rolled material onto the reel, the influence of reel eccentricity on the sheet thickness at the outlet side of the rolling mill can be reduced.

[0021] According to the second aspect, by using the speed of the rolled material measured by the sheet speed meter, it is possible to accurately calculate the moving distance of the rolled material after being rolled by the rolling mill.

[0022] According to the third aspect, by compensating for various delays, it is possible to accurately determine the input timing and the output timing.

[0023] According to the fourth aspect, by multiplying the stored sheet thickness deviation by the forgetting coefficient λ, the weight of the stored sheet thickness deviation can be reduced when adding the sheet thickness deviation. The fourth aspect can be well applied to the case where the correspondence between the rotation angle of the reel and the sheet thickness deviation measurement position deviates over time.

[0024] According to the fifth aspect, an adjustment coefficient corresponding to the coil diameter can be used to adjust the operation amount of the roll gap control device.

[0025] However, when the roll gap control device is operated to reduce the sheet thickness variation caused by the reel eccentricity, sometimes the tensions on the entry side and the exit side of the rolling mill change, and the deviation between the tension measured by the tension meter and the tension target value becomes large. In this case, if the tension control is performed such that the measured tension becomes the tension target value, it may instead have an adverse effect on the sheet thickness on the exit side of the rolling mill (deterioration of the sheet thickness control accuracy). Therefore, by calculating the correction amount of the tension target value and correcting the tension target value as in the sixth aspect, it is possible to prevent an adverse effect on the sheet thickness on the exit side of the rolling mill. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram showing the configuration of the sheet thickness control device of the rolling mill according to the embodiment.

[0027] Figure 2 is a schematic diagram showing the configuration of the process control computer which is the sheet thickness control device of the rolling mill according to the embodiment.

[0028] Figure 3 is a diagram for explaining dividing the reel into equal rotation angles and assigning division numbers to the divided parts.

[0029] Figure 4 is a diagram showing the first table stored in the sheet thickness deviation input determination unit.

[0030] Figure 5 is a diagram showing the second table stored in the sheet thickness deviation storage unit.

[0031] Figure 6 is a diagram for explaining an example of setting the adjustment coefficient.

[0032] Figure 7 is a diagram showing an example of the hardware configuration of the process control computer implementing the sheet thickness control device.

[0033] Figure 8 is a diagram for explaining the eccentricity of the reel. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, with reference to the drawings, taking as an example the case of applying to a rolling mill provided in a cold rolling mill set RP, embodiments of the present invention will be described. In addition, in each figure, the same reference numerals are assigned to common elements and redundant explanations are omitted.

[0035] Figure 1It is a schematic diagram showing the configuration of a cold rolling plant to which a plate thickness control device of a rolling mill according to an embodiment is applied. The rolling mill 1 uses steel or other metal materials as the rolling material M and rolls the rolling material M into a specified target product plate thickness.

[0036] The rolling mill 1 includes one rolling stand 11. The rolling stand 11 includes a pair of upper and lower work rolls 111, a pair of upper and lower backup rolls 112, and a motor 113 for roll rotation. A screw-down device 114 is provided on the backup roll 112, and the screw-down opening of the screw-down device 114 is controlled by a screw-down opening control device 115, thereby controlling the roll gap between the upper and lower work rolls 111.

[0037] An entry side reel 2 is arranged on the entry side of the rolling mill 1, and an exit side reel 3 is arranged on the exit side of the rolling mill 1. The rolling material M wound on the entry side reel 2 is transported in one direction (from left to right) as indicated by the arrow while being rolled by the rolling mill 1 and then taken up by the exit side reel 3. In addition, when the rolling mill 1 is a reversing mill, the rolling material M is rolled back and forth between the two reels 2 and 3 multiple times until the target plate thickness is achieved.

[0038] Motors 21 and 31 for reel rotation are provided on the entry side reel 2 and the exit side reel 3, respectively, and the motors 21 and 31 are controlled by torque control devices 22 and 32. Rotation angle detectors 4 and 5 for detecting the rotation angle of each reel 2 and 3 are respectively provided on the entry side reel 2 and the exit side reel 3. As the rotation angle detectors 4 and 5, for example, known detectors composed of a pulse generator, a counter, etc. can be used, so further description is omitted. In addition, tension gauges 6 and 7 for measuring the tension of the rolling material M are respectively provided between the entry side reel 2 and the rolling mill 1 and between the exit side reel 3 and the rolling mill 1. The torque control devices 22 and 32 determine the torque (or current) of the motors 21 and 31 based on the correction amount of the tension control, and the tension control is performed in such a way that the tensions of the rolling material M on the entry side and the exit side of the rolling mill 1 measured by the torque (or current) tension gauges 6 and 7 become the given tension target values.

[0039] A sheet speed meter 8 for measuring the speed of the rolling material M and a sheet thickness meter 9 for measuring the actual plate thickness of the rolling material M are provided on the exit side of the rolling mill 1. In addition, although not shown in the figure, when the rolling mill 1 is a reversing mill, a sheet speed meter and a sheet thickness meter are also provided on the entry side of the rolling mill 1.

[0040] The cold rolling plant RP is operated (manipulated) by a computer-based control system. The computer includes a host computer 40 and a process control computer 41 that are interconnected via a network. The process control computer 41 is connected to an interface screen 42, which is the operation screen of the operator, via a network. The operator can perform input operations of control conditions and the like on the interface screen 42.

[0041] The process control computer 41 performs setting calculations and control of control objects during a series of rolling processes. In addition, the process control computer 41 also has a function of controlling the screw-down opening of the screw-down device 114. The target plate thickness (product plate thickness) h of the rolled material M is input to the process control computer 41 from the host computer 40 REF [mm].

[0042] Based on the target plate thickness h REF [mm], control conditions given from the interface screen 42, etc., the process control computer 41 appropriately controls each device. The process control computer 41 calculates the settings of each device that can achieve the target plate thickness h REF , and operates the actuators of each device based on these set values. During the operation of each device, the actions of the actuators are corrected according to the values obtained from various measuring instruments. The process control computer 41 operates the screw-down device 114 of the rolling stand 11 of the rolling mill 1 to adjust the roll gap so that the measured plate thickness (actual plate thickness) h of the rolled material M becomes the target plate thickness (that is, the plate thickness deviation is eliminated).

[0043] In the present embodiment, since the responsiveness is low if the motors 21 and 31 are controlled to keep the tension constant when tension fluctuations caused by reel eccentricity occur, it is characterized in that instead of this tension constant control, the screw-down device 114 with higher responsiveness is operated. Hereinafter, the plate thickness control device having this feature will be described in detail.

[0044] Figure 2 is a schematic diagram showing the configuration of the process control computer 41 which is the plate thickness control device of the rolling mill according to the embodiment. Figure 3 is a diagram for explaining dividing the reels 2 and 3 by equal rotation angles and the division numbers given to the divided parts. Figure 4 is a diagram showing the first table Tb1 stored in the plate thickness deviation input determination unit. Figure 5 is a diagram showing the second table Tb2 stored in the plate thickness deviation storage unit.

[0045] The process control computer 41 includes a moving distance calculation unit 411, a reel rotation angle calculation unit 412 (412a, 412b), a plate thickness deviation calculation unit 413, a plate thickness deviation input determination unit 414 (414a, 414b), a plate thickness deviation storage unit 415 (415a, 415b), a plate thickness deviation output determination unit 416 (416a, 416b), and an operation amount calculation unit 417 (417a, 417b).

[0046] In addition, in the present embodiment, for the sake of simplicity of explanation, the first reel rotation angle calculation unit 412a and the second reel rotation angle calculation unit 412b are not separately described, but are described as the reel rotation angle calculation unit 412. The same applies to the plate thickness deviation input determination unit 414, the plate thickness deviation storage unit 415, the plate thickness deviation output determination unit 416, and the operation amount calculation unit 417.

[0047] The moving distance calculation unit 411 calculates the distance ΔL that the rolled material M advances during the operation cycle Δt [sec] according to the following formula (1) based on the speed v [m / s] of the rolled material M measured by the plate speed meter 8. The operation cycle Δt can be set according to the speed v [m / s] of the rolled material M, and can be set to 20 msec, for example.

[0048] ΔL = v × 1000 × Δt ··· (1)

[0049] In addition, when the plate speed meter 8 is not provided on the output side of the rolling mill 1, or when the plate speed meter 8 cannot be used due to a failure or the like, the moving distance ΔL of the rolled material M can also be calculated according to the circumferential speed of the work roll of the rolling mill 1 (hereinafter referred to as "roll circumferential speed") V R [m / s] and the forward slip ratio f according to the following formula (2).

[0050] ΔL = V R × (1 + f) × Δt ··· (2)

[0051] The reel rotation angle calculation unit 412 sets the rotation angle value detected by the rotation angle detector 4 as the rotation angle of the inlet side reel 2, and sets the rotation angle value detected by the rotation angle detector 5 as the rotation angle of the outlet side reel 3. When the rotation angle detectors 4 and 5 emit pulses corresponding to the rotation of the respective reels 2 and 3, the reel rotation angle calculation unit 412 can count the pulses emitted by the rotation angle detectors 4 and 5 and calculate the rotation angles of the respective reels 2 and 3.

[0052] The plate thickness deviation calculation unit 413 calculates the plate thickness deviation Δh MEAS [mm] according to the following formula (3) based on the plate thickness measurement value h x [mm] measured by the plate thickness meter 9.

[0053] Δh x = h MEAS - h REF ··· (3)

[0054] In the above formula (3), h REF is the target plate thickness value [mm]. In addition, when the plate thickness deviation Δh x [mm] is transmitted from the plate thickness meter 9 to the plate thickness deviation calculation unit 413, it can be used directly.

[0055] The sheet thickness deviation input determination unit 414 determines the timing for inputting the sheet thickness deviation Δh calculated by the sheet thickness deviation calculation unit 413 x to the sheet thickness deviation storage unit 415. As Figure 3 shown, one revolution of each of the inlet side reel 2 and the outlet side reel 3 is divided into N equal rotation angles, and division numbers from 0 to N - 1 are assigned in advance. As Figure 4 shown, the sheet thickness deviation input determination unit 414 has a first table Tb1 capable of storing N elements corresponding to the division numbers N (i.e., division number n) of each of the inlet side reel 2 and the outlet side reel 3. In the first table Tb1, the distance L 0 ~L N-1 .

[0056] When it becomes the calculation timing (control cycle k), the sheet thickness deviation input determination unit 414 adds the moving distance ΔL calculated by the moving distance calculation unit 411 to each element in the lower row of the first table Tb1 (refer to the following formula (4)). For example, when the rolled material M moves 50 mm in each calculation cycle Δt, the distance L 0 ~L N-1 of each element is added by 50 mm at each calculation timing. The control cycle k can be the same as the calculation cycle Δt or different from the calculation cycle Δt

[0057] Ln[k]=Ln[k - 1]+ΔL[k]···(4)

[0058] In the above formula (4), Ln[k] is the moving distance [mm] of the part of the rolled material M rolled at the division number n in the control cycle k from the rolling mill 1, and ΔL[k] is the moving distance [mm] in the control cycle k calculated by the moving distance calculation unit 411

[0059] Next, the sheet thickness deviation input determination unit 414 judges the input timing. Here, it can be considered that the division number n - 1 of the sheet thickness deviation storage unit 415 is the moment when the input of the sheet thickness deviation ends. At this time, the sheet thickness deviation input determination unit 414 confirms whether the division number n reaches the input timing. That is, when the following formula (5) is satisfied, the sheet thickness deviation input determination unit 414 determines that it is the input timing of the division number n

[0060] Ln[k]≥L x ···(5)

[0061] In the above formula (5), L xis the distance between the rolling mill 1 and the thickness gauge 9 provided on the exit side of the rolling mill 1. When the above formula (5) is not satisfied, at the next operation timing, it is confirmed again whether the division number n has reached the input timing. This confirmation is sequentially repeated from division number 0 to N - 1. If it reaches division number N - 1, the division number 0 is returned.

[0062] Moreover, the sheet thickness deviation input determination unit 414 sets the distance Ln from the rolling mill 1 corresponding to the division number n to zero if the rotation angles of the input side reel 2 and the output side reel 3 calculated by the reel rotation angle calculation units 412a and 412b reach the rotation angle corresponding to the division number n.

[0063] Through the above series of operations, it can be known at which rotation angle corresponding to each division number of the input side reel 2 and the output side reel 3 the sheet thickness measured by the thickness gauge 9 is rolled.

[0064] However, the measurement delay of the thickness gauge 9 is not considered in the operation of the above sheet thickness deviation input determination unit 414. Therefore, depending on the degree of this delay, the sheet thickness control becomes vibratory. Therefore, it is preferable to compensate for the measurement delay of the thickness gauge 9 as a first-order delay. In addition, delays caused by signal transmission and calculation occur, and it is preferable to include these delays for compensation. As a compensation method, instead of the above formula (5), the following formulas (6) and (7) are used for the input side reel 2, and the following formulas (8) and (9) are used for the output side reel 3 to determine the input timing.

[0065]

[0066] In the above formulas (6) to (9), L n＿ENT 、L n＿DEL is the moving distance [mm] of the portion rolled at the division number n of the input side reel 2 from the rolling mill 1, and the moving distance [mm] of the portion rolled at the division number n of the output side reel 3 from the rolling mill 1. D ENT 、D DEL are the coil diameters [mm] of the rolled material M wound on the input side reel 2 and the output side reel 3, H is the input side sheet thickness [mm], and h is the output side sheet thickness [mm]. T x is the thickness gauge time constant [s], ω ENT 、ω DEL are the rotational angular velocities [rad / s] of the input side reel 2 and the output side reel 3.

[0067] Here, the rotational angular velocities ω ENT 、ω DEL[rad / s], for example, can be obtained by taking the difference of the rotation angles calculated by the reel rotation angle calculation unit 412. By compensating for the measurement delay of the thickness gauge 9 as described above, it is possible to improve the accuracy of the thickness control.

[0068] The thickness deviation storage unit 415 has the same structure as the thickness deviation input determination unit 414. As Figure 5 shown, the thickness deviation storage unit 415 has a second table Tb2 that can store N elements corresponding to the number of divisions N (i.e., division number n) of each of the inlet side reel 2 and the outlet side reel 3. In the second table Tb2, the cumulative value of the thickness deviation obtained by adding the thickness deviations calculated by the thickness deviation calculation unit 413 based on the input timing determined by the thickness deviation input determination unit 414 is stored in correspondence with the rotation angles of the inlet side reel 2 and the outlet side reel 3 when the rolled material M is rolled by the rolling mill 1, that is, the division number n (n = 0 to N - 1). For example, at the input timing of the division number n, the thickness deviation storage unit 415 performs the operation of the following formula (10), and stores the operation result again as the cumulative value of the thickness deviation under the division number n in the lower part of the second table Tb2.

[0069] Δh n [k]=λ×Δh n [k - 1]+Δh x [k]···(10)

[0070] In the above formula (10), Δh n [k] is the cumulative value [mm] of the thickness deviation for the division number n in the control period k, λ is a forgetting coefficient taking a value between 0 and 1, and Δh x [k] is the thickness deviation [mm] in the control period k calculated by the thickness deviation calculation unit 413.

[0071] Here, when the forgetting coefficient λ is set to 1, the thickness deviation in the control period k and the thickness deviations stored (already stored) before the control period k (k - 1, k - 2,...) are stored with equal weights. On the other hand, by multiplying the thickness deviation stored before the control period k by the forgetting coefficient λ, the weight of the thickness deviation stored before the control period k can be reduced. For example, in the case where the correspondence between the division number (rotation angle) and the thickness deviation measurement position deviates over time, by setting the forgetting coefficient λ to less than 1, the weight of the thickness deviation measured in the past can be reduced, and as a result, it is possible to improve the accuracy of the thickness control, which is more advantageous.

[0072] The sheet thickness deviation output determination unit 416 determines the timing for outputting the cumulative value of the sheet thickness deviation from the sheet thickness deviation storage unit 415. That is, the sheet thickness deviation output determination unit 416 determines the output timing of the cumulative value of the sheet thickness deviation corresponding to the division number when the rotation angles of the input-side reel 2 and the output-side reel 3 calculated by the reel rotation angle calculation unit 412 become the rotation angles corresponding to the division number.

[0073] At this time, similar to the sheet thickness deviation input determination unit 414, the sheet thickness deviation output determination unit 416 preferably sets the response delay of the pressing device 114 to one-time delay to compensate for the response delay of the pressing device 114. For example, the output timing for the division number n is determined by using the following formulas (11) and (12) for the input-side reel 2 and formulas (13) and (14) for the output-side reel 3, respectively.

[0074]

[0075] In the above formulas (11) to (14), θ ENT and θ DEL are the input-side reel rotation angle [rad] and the output-side reel rotation angle [rad], respectively, and θ n is the rotation angle [rad] corresponding to the division number n. T H is the time constant [s] of the pressing device 114, and ω ENT and ω DEL are the rotation angular velocities [rad / s] of the input-side reel 2 and the output-side reel 3, respectively.

[0076] The operation amount calculation unit 417 calculates the correction amount of the roll gap control device 115 based on the output timing determined by the sheet thickness deviation output determination unit 418. For example, at the output timing of the division number n, the operation amount calculation unit 417 performs the calculation of the following formula (15) and outputs the calculation result ΔS to the roll gap control device 115.

[0077] ΔS = {K × M / (M + Q) × Δh n} ··· (15)

[0078] In the above formula (15), ΔS is the roll gap operation amount of the pressing device 114 (hereinafter also referred to as "operation amount") [mm], K is the adjustment coefficient, M is the mill constant [kN / mm] of the rolling mill 1, Q is the plastic coefficient [kN / mm] of the rolled material M, and Δh n is the cumulative value of the sheet thickness deviation of the division number n [mm].

[0079] Here, the influence of the eccentricity of the reels 2 and 3 is larger when the coil diameter (also referred to as the coil diameter) of the rolled material M wound around the reels 2 and 3 is smaller, and gradually decreases as the coil diameter increases. Therefore, it is also possible to Figure 6As shown, the adjustment coefficient K is preset in accordance with the change in the coil diameter. When calculating the rolling reduction opening operation amount ΔS, the adjustment coefficient K corresponding to the coil diameter is obtained, and the obtained adjustment coefficient K is used (multiplied) to adjust the operation amount ΔS. Accordingly, when the coil diameter is small, the sheet thickness control effect based on the operation amount ΔS can be improved, and when the coil diameter is large, the rolling reduction opening operation amount ΔS can be suppressed so as not to become an external disturbance to the sheet thickness control.

[0080] Moreover, the operation amount calculation unit 417 may also be configured to set upper and lower limit values for the operation amount (correction amount) ΔS of the rolling reduction opening control device 115 obtained by the above formula (15) as shown in the following formula (16), and when it exceeds this range, the operation amount ΔS is set to the upper and lower limit values.

[0081] ΔS LL ≤ΔS≤ΔS UL ···(16)

[0082] In the above formula (17), ΔS LL is the lower limit value, and ΔS UL is the upper limit value. When the calculated operation amount ΔS is lower than the lower limit value ΔS LL , the operation amount ΔS is replaced with the lower limit value ΔS LL , and when it exceeds the upper limit value ΔS UL , the operation amount ΔS is replaced with the upper limit value ΔS UL . Accordingly, although the operation amount ΔS is restricted and there is a sheet thickness deviation, stable rolling of the rolling mill 1 can be achieved by preventing instability of the rolling reduction opening control.

[0083] However, when the press-down device 114 is operated, the tensions on the entry side and the exit side of the rolling mill 1 change. As a result, the deviation between the tensions measured by the tensiometers 6 and 7 and the tension target value becomes larger. If the tension control is performed in such a way that the measured tension becomes the tension target value (that is, if the excessive tension control is performed in such a way that the deviation disappears), it may have an adverse effect on the sheet thickness on the exit side of the rolling mill 1 (the accuracy of the sheet thickness control deteriorates). To suppress this influence, the operation amount calculation unit 417 calculates the correction amount of the tension target value based on the operation amount ΔS of the press-down opening, and corrects the tension target value. As a result, the deviation between the corrected tension target value and the tension target value becomes smaller than before the correction, and the excessive tension control is not performed, so that it is possible to prevent an adverse effect on the sheet thickness on the exit side of the rolling mill 1. At this time, similar to the operation amount ΔS of the press-down opening of the press-down device 114, upper and lower limit values can also be set for the correction amount of the tension target value, and the correction can be performed within the range. Here, the relationship between the operation amount ΔS of the press-down opening and the change in tension can be preset in such a way that the press-down opening of the press-down device 114 is changed through experiments and the change in tension at this time is measured, or the correlation between the press-down opening change amount (ΔS) and the tension change amount is obtained through simulation.

[0084] The specific configuration of the process control computer 41 is not limited, but as an example, it can be as follows. Figure 7 is a diagram showing an example of the hardware configuration of the process control computer 41. The functions of the process control computer 41 can be realized by Figure 7 the processing circuit shown. This processing circuit can be the dedicated hardware 41a. This processing circuit can also include a processor 41b and a memory 41c. This processing circuit can also be such that a part thereof is formed as the dedicated hardware 41a, and includes a processor 41b and a memory 41c. Figure 7 An example of this is that a part of the processing circuit is formed as the dedicated hardware 41a, and the processing circuit also includes a processor 41b and a memory 41c.

[0085] At least a part of the processing circuit can also be at least one dedicated hardware 41a. In this case, the processing circuit corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a circuit formed by combining these.

[0086] The processing circuit can also include at least one processor 41b and at least one memory 41c. In this case, the respective functions of the process control computer 41 are realized by software, firmware, or a combination of software and firmware. The software and the firmware are described as programs and stored in the memory 41c. The processor 41b reads and executes the programs stored in the memory 41c, thereby realizing the functions of the respective parts of the sheet thickness control device 41.

[0087] The processor 41b is also known as a CPU (Central Processing Unit), a central processing device, a processing device, an arithmetic unit, a microprocessor, a microcomputer, or a DSP. The memory 41c corresponds to, for example, a non-volatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM.

[0088] In this way, the processing circuit can implement the various functions of the process control computer 41 through hardware, software, firmware, or a combination of these.

[0089] As described above, according to the present invention, the plate thickness on the output side of the rolling mill 1 is measured by the thickness gauge 9, and the plate thickness deviation between the measured plate thickness and the target plate thickness value is correlated with the rotation angles of the reels 2 and 3, whereby the periodic plate thickness variation (the influence on the plate thickness on the output side of the rolling mill 1) caused by the reel eccentricity can be extracted. The correction amount of the screw-down opening control device 115 is calculated based on the plate thickness variation extracted corresponding to the rotation angles of the reels 2 and 3, and the screw-down device 114, which responds faster than the conventional speed control system, is operated. Thus, even if the tension of the rolled material M changes due to the reel eccentricity caused by the winding of the reels 2 and 3, the influence of the reel eccentricity on the plate thickness of the rolled material M on the output side of the rolling mill 1 can be reduced. As a result, the plate thickness accuracy on the output side of the rolling mill 1 can be maintained well.

[0090] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various modifications can be made and implemented without departing from the gist of the present invention. When numerical values such as the number, quantity, amount, and range of each element are mentioned in the above embodiments, the present invention is not limited to the mentioned numerical values, except in cases where it is specifically stated or determined to that value in principle. In addition, the structures and the like described in the above embodiments are not essential to the present invention, except in cases where it is specifically stated or determined thereto in principle.

[0091] In the above-described embodiment, the measurement delay of the thickness gauge 9 and the delays caused by signal transmission and calculation are compensated by the plate thickness deviation input determination unit 414, and the response delay of the rolling-down device 114 is compensated by the plate thickness deviation output determination unit 416. However, the present invention is not limited thereto. It is also possible to compensate the measurement delay of the thickness gauge 9 by the plate thickness deviation input determination unit 414 and compensate the response delay of the rolling-down device 114 and the delays caused by signal transmission and calculation by the plate thickness deviation output determination unit 416. In this case, the same effect as that of the above-described embodiment can also be obtained. Moreover, it is also possible to compensate the measurement delay of the thickness gauge 9, the response delay of the rolling-down device 114, and the delays caused by signal transmission and calculation all at once by the plate thickness deviation input determination unit 414. In this case, in addition to obtaining the same effect as that of the above-described embodiment, it is also possible to make the software design easier. Additionally, it is also possible to compensate the measurement delay of the thickness gauge 9, the response delay of the rolling-down device 114, and the delays caused by signal transmission and calculation all at once by the plate thickness deviation output determination unit 116. Further, it is possible to compensate at least one of the measurement delay of the thickness gauge 9, the delays caused by signal transmission and calculation, and the response delay of the rolling-down device 114 of the rolling mill 1.

[0092] In the above-described embodiment, the moving direction of the rolled material M is set as Figure 1 the direction from left to right indicated by the arrow in the figure. However, the present invention is not limited thereto. Even when the moving direction is the opposite direction (from right to left), the present invention can also be applied.

[0093] Additionally, in the above-described embodiment, the case where torque control is performed on the motors 21 and 31 of the reels 2 and 3 is taken as an example for description. However, the present invention can also be applied in the case of speed control.

[0094] Moreover, in the above-described embodiment, the case where a four-high rolling mill (rolling mill having 4 rolls 111 and 112) 1 is used is taken as an example for description. However, the rolling mill 1 is not limited thereto. In the above-described embodiment, the case where the rolling mill 1 includes one rolling mill stand 11 is taken as an example for description. However, it may also include two or more rolling mill stands. In this case, the operation amount ΔS of the rolling-down opening of the rolling-down device of each rolling mill stand may be calculated in the same manner as in the above-described embodiment.

[0095] Description of symbols

[0096] 1: Rolling mill, 114: Gauge control device, 2: Inlet side reel, 3: Outlet side reel, 4, 5: Rotary angle detector, 6, 7: Tensiometer, 8: Sheet speed meter, 9: Sheet thickness meter, 41: Sheet thickness control device, Process control computer, 411: Moving distance calculation unit, 412: Reel rotation angle calculation unit, 413: Sheet thickness deviation calculation unit, 414: Sheet thickness deviation input determination unit, 415: Sheet thickness deviation storage unit, 416: Sheet thickness deviation output determination unit, 417: Operation amount calculation unit, M: Rolled material.

Claims

1. A plate thickness control device for a rolling mill, wherein, a thickness gauge is provided on the outlet side of the rolling mill, and the plate thickness control device includes: a moving distance calculation unit that calculates the distance that the rolled material after being rolled by the rolling mill moves from the rolling mill; a reel rotation angle calculation unit that calculates the rotation angle of a reel provided on at least one of the inlet side and the outlet side of the rolling mill; a plate thickness deviation calculation unit that calculates a plate thickness deviation based on the plate thickness measurement value of the rolled material measured by the thickness gauge; a plate thickness deviation input determination unit that determines the input timing of the plate thickness deviation based on the moving distance of the rolled material calculated by the moving distance calculation unit and the rotation angle of the reel calculated by the reel rotation angle calculation unit; a plate thickness deviation storage unit that adds and stores the plate thickness deviation calculated by the plate thickness deviation calculation unit based on the input timing determined by the plate thickness deviation input determination unit; a plate thickness deviation output determination unit that determines the output timing of the plate thickness deviation based on the rotation angle of the reel calculated by the reel rotation angle calculation unit; and an operation amount calculation unit that reads out the cumulative value of the plate thickness deviation stored in the plate thickness deviation storage unit based on the output timing determined by the plate thickness deviation output determination unit, and calculates the operation amount of the screw-down device of the rolling mill based on this cumulative value.

2. The plate thickness control device for a rolling mill according to claim 1, wherein, a plate speed meter is provided on the outlet side of the rolling mill, and the moving distance calculation unit calculates the moving distance of the rolled material after being rolled by the rolling mill based on the speed of the rolled material measured by the plate speed meter.

3. The plate thickness control device for a rolling mill according to claim 1, wherein, the plate thickness deviation input determination unit and the plate thickness deviation output determination unit are configured to compensate for at least one of the measurement delay of the thickness gauge, the delay caused by signal transmission and calculation, and the response delay of the screw-down device of the rolling mill, and respectively determine the input timing and the output timing.

4. The plate thickness control device for a rolling mill according to claim 1, wherein, the plate thickness deviation storage unit is configured to multiply the plate thickness deviation already stored in the plate thickness deviation storage unit by a forgetting factor less than 1, and add the plate thickness deviation calculated by the plate thickness deviation calculation unit.

5. The plate thickness control device for a rolling mill according to claim 1, wherein, the operation amount calculation unit is configured to obtain an adjustment coefficient corresponding to the coil diameter of the rolled material wound on the reel when calculating the operation amount of the screw-down device, and use the obtained adjustment coefficient to adjust the operation amount.

6. The plate thickness control device for a rolling mill according to any one of claims 1 to 5, wherein, a tension meter is provided on at least one of the inlet side and the outlet side of the rolling mill, and the motor of the reel is controlled so that the tension measured by the tension meter becomes a tension target value, and the operation amount calculation unit is configured to calculate a correction amount of the tension target value based on the operation amount of the screw-down device.

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