Rolling mill thickness control device

Abstract

In the present invention, a movement distance calculation unit calculates the movement distance of a rolled stock from a rolling mill. A reel rotation angle calculation unit calculates a rotation angle of a reel installed on at least one of the entrance side and the exit side at the rolling mill. A plate thickness deviation calculation unit calculates a plate thickness deviation. A 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 stock calculated by the movement distance calculation unit and the rotation angle of the reel calculated by the reel rotation angle calculation unit. A plate thickness deviation storage unit adds and stores the plate thickness deviation calculated by the plate thickness deviation calculation unit on the basis of the input timing determined by the plate thickness deviation input determination unit. A 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. An operation amount calculation unit reads, on the basis of the output timing determined by the plate thickness deviation output determination unit, the integrated value of the plate thickness deviations stored in the plate thickness deviation storage unit and calculates an operation amount of a screw-down device in the rolling mill on the basis of the integrated value.

Description

[Technical Field]

[0001] The present disclosure relates to a plate thickness control device for a rolling mill, and in particular to a device that is suitably applied to a rolling mill that cold rolls metals or the like. [Background technology]

[0002] For example, in a rolling process, the thickness of the material being rolled is controlled to a target thickness value (also called the product thickness or set thickness) by appropriately adjusting the gap between the upper and lower work rolls of the rolling mill (hereinafter referred to as the "roll gap") using a reduction device.

[0003] A rolling mill typically has a reel on at least one of the entry and exit sides that winds the rolled material. With such reels, the leading edge of the rolled material is typically inserted into the gap in the mandrel that winds the material. In this case, the leading edge of the rolled material bulges, causing the reel to become eccentric, as shown in Figure 8. This results in tension fluctuations in the rolled material between the rolling mill and the reel with each rotation of the reel. These tension fluctuations affect the thickness of the plate at the exit of the rolling mill, resulting in a decrease in product quality.

[0004] Methods for suppressing the above-mentioned tension fluctuations are proposed in, for example, Patent Documents 1 and 2. In Patent Document 1, tension deviations are stored in a shift register according to the reel rotation angle, and a value corresponding to the rotation angle is extracted from the shift register. Based on this, the motor torque of the reel is controlled, thereby suppressing tension fluctuations due to reel eccentricity. In Patent Document 2, the amount of reel diameter fluctuation is stored in association with the reel rotation position, and a correction value for the reel rotation speed is generated based on this reel diameter fluctuation, and the reel rotation speed is controlled to suppress tension fluctuations. In both methods, reducing tension fluctuations due to reel eccentricity aims to improve plate thickness accuracy, which is an indicator of product quality. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 11-285730 [Patent Document 2] Japanese Patent Publication No. 2015-36150 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in Patent Document 1, a phase lead element is inserted to take into account response delays in the current control system, tension generation system, and tension detector, but because the tension generation system is a physical phenomenon, there may be a deviation from the delay estimated by the theoretical formula, making it difficult to sufficiently suppress tension fluctuations.In Patent Document 2, the rotational speed is corrected based on the amount of fluctuation in the reel diameter to prevent a speed difference from the rolling mill, but because the response of the speed control system is generally not very fast, there is a risk that tension fluctuations due to reel eccentricity may not be sufficiently reduced.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a plate thickness control device for a rolling mill that can reduce the effect of reel eccentricity on the plate thickness at the exit side of the rolling mill, even if tension fluctuations in the rolled material occur due to reel eccentricity caused by winding the rolled material around the reel. [Means for solving the problem]

[0008] The first aspect relates to a thickness control device for a rolling mill. A thickness gauge is installed on the delivery side of the rolling mill, and a tension gauge is installed on at least one of the entry side and exit side of the rolling mill, and the reel motor is controlled so that the tension measured by the tension gauge becomes a target tension value. The thickness control device includes a travel distance calculation unit, a reel rotation angle calculation unit, a thickness deviation calculation unit, a thickness deviation input determination unit, a thickness deviation storage unit, a thickness deviation output determination unit, and an operation amount calculation unit. The travel distance calculation unit calculates the distance traveled from the rolling mill by the rolled material rolled by the rolling mill. The reel rotation angle calculation unit calculates the rotation angle of a reel installed on at least one of the entry side and exit side of the rolling mill. The thickness deviation calculation unit calculates the thickness deviation based on the thickness measurement value of the rolled material measured by the thickness gauge. The thickness deviation input determination unit determines the input timing of the thickness deviation based on the movement distance of the rolled material calculated by the movement distance calculation unit and the reel rotation angle calculated by the reel rotation angle calculation unit.The thickness deviation storage unit adds and stores the thickness deviation calculated by the thickness deviation calculation unit based on the input timing determined by the thickness deviation input determination unit.The thickness deviation output determination unit determines the output timing of the thickness deviation based on the reel rotation angle calculated by the reel rotation angle calculation unit.The operation amount calculation unit reads out the integrated value of the thickness deviation stored in the thickness deviation storage unit based on the output timing determined by the thickness deviation output determination unit, and calculates the operation amount of the reduction device of the rolling mill based on this integrated value. The screw down device is operated based on the operation amount of the screw down device calculated by the operation amount calculation unit. The operation amount calculation unit is configured to calculate a correction amount for the tension target value based on the operation amount of the screw down device.

[0009] The second aspect has the same features as the first aspect, but further includes the following: a strip speed meter is provided on the delivery side of the rolling mill, and a travel distance calculation unit calculates the travel distance of the rolled material rolled by the rolling mill based on the speed of the rolled material measured by the strip speed meter.

[0010] The third aspect has the following characteristics in addition to the first aspect: The thickness deviation input determination unit and the thickness deviation output determination unit are configured to determine the input timing and the output timing, respectively, by compensating for at least one of a delay in measurement by the thickness gauge, a delay due to signal transmission or calculation, and a response delay of the screw down device of the rolling mill.

[0011] The fourth aspect has the following characteristics in addition to the first aspect: The thickness deviation storage unit is configured to multiply the thickness deviation stored in the thickness deviation storage unit by a forgetting factor smaller than 1, and add the thickness deviation calculated by the thickness deviation calculation unit.

[0012] The fifth aspect has the following feature in addition to the first aspect: when calculating the manipulated variable of the screw down device, the manipulated variable calculation unit is configured to obtain an adjustment coefficient corresponding to the coil diameter of the rolled material wound around the reel, and adjust the manipulated variable using the obtained adjustment coefficient. [Effects of the Invention]

[0014] According to the first aspect, by associating the thickness deviation with the reel rotation angle, periodic thickness fluctuations due to reel eccentricity can be extracted. The amount of operation of the screw down device is calculated from the thickness fluctuations extracted according to the reel rotation angle, and the screw down device is operated with a faster response than conventional speed control systems. Therefore, even if tension fluctuations in the rolled material occur due to reel eccentricity caused by winding the rolled material onto the reel, the impact of reel eccentricity on the thickness at the delivery side of the rolling mill can be reduced.

[0015] According to the second aspect, by using the speed of the rolled material measured by the strip speed meter, it is possible to accurately calculate the travel distance of the rolled material rolled by the rolling mill.

[0016] According to the third aspect, various delays are compensated for, thereby making it possible to determine input timing and output timing with high precision.

[0017] According to the fourth aspect, by multiplying the stored thickness deviation by the forgetting factor λ, the weight of the stored thickness deviation can be reduced when adding up the thickness deviations. The fourth aspect can be suitably applied to a case where the correspondence relationship between the reel rotation angle and the thickness deviation measurement point shifts over time.

[0018] According to the fifth aspect, the operation amount of the screw down device can be adjusted using an adjustment coefficient according to the coil diameter.

[0019] Incidentally, when the screw down device is operated to reduce thickness fluctuations due to reel eccentricity, the tension on the entry side and delivery side of the rolling mill changes, and the deviation between the tension measured by the tension meter and the target tension value may become large. In this case, if tension control is performed so that the measured tension becomes the target tension value, there is a risk that this will have an adverse effect on the thickness of the strip on the delivery side of the rolling mill (deteriorating the accuracy of strip thickness control). Therefore, as in the sixth aspect, by calculating a correction amount for the target tension value and correcting the target tension value, it is possible to prevent adverse effects on the thickness of the strip on the delivery side of the rolling mill. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic diagram showing a configuration of a plate thickness control device for a rolling mill according to an embodiment. [Figure 2] 1 is a schematic diagram showing a configuration of a process control computer that is a plate thickness control device for a rolling mill according to an embodiment. FIG. [Figure 3] FIG. 10 is a diagram illustrating division numbers assigned to the divided portions obtained by dividing a reel at equal rotation angles. [Figure 4] FIG. 4 is a diagram showing a first table stored by a plate thickness deviation input determination unit. [Figure 5] FIG. 10 is a diagram showing a second table stored in the plate thickness deviation storage unit. [Figure 6] FIG. 10 is a diagram illustrating an example of setting an adjustment coefficient. [Figure 7] FIG. 1 is a diagram illustrating an example of a hardware configuration of a process control computer that implements a plate thickness control device. [Figure 8] FIG. 10 is a diagram illustrating eccentricity of the reel. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, with reference to the drawings, an embodiment of the present disclosure will be described, taking as an example a case where the present disclosure is applied to a rolling mill installed in a cold rolling plant RP. Note that elements common to the various drawings are assigned the same reference numerals, and duplicated explanations will be omitted.

[0022] 1 is a schematic diagram showing the configuration of a cold rolling plant to which a rolling mill thickness control device according to an embodiment is applied. The rolling mill 1 rolls steel or other metallic material as a rolled material M to a predetermined target product thickness.

[0023] The rolling mill 1 has one rolling stand 11. The rolling stand 11 has a pair of upper and lower work rolls 111, a pair of upper and lower backup rolls 112, and an electric motor 113 for rotating the rolls. The backup rolls 112 are provided with a screw down device 114, and the screw down opening of the screw down device 114, and therefore the roll gap between the upper and lower work rolls 111, is controlled by a screw down opening control device 115.

[0024] An entry reel 2 is arranged on the entry side of the rolling mill 1, and an exit reel 3 is arranged on the exit side of the rolling mill 1. The rolled material M wound around the entry reel 2 is rolled by the rolling mill 1 while being transported in one direction (from left to right) as indicated by the arrow, and is then wound up on the exit reel 3. If the rolling mill 1 is a reversible type, the rolled material M is rolled back and forth between the reels 2 and 3 multiple times until it reaches the target thickness.

[0025] The entry reel 2 and the delivery reel 3 are provided with electric motors 21 and 31 for rotating the reels, and the electric motors 21 and 31 are controlled by torque control devices 22 and 32. The entry reel 2 and the delivery reel 3 are provided with rotation angle detectors 4 and 5, respectively, for detecting the rotation angles of the reels 2 and 3. Known devices such as pulse generators and counters can be used as the rotation angle detectors 4 and 5, and further explanation will be omitted. Furthermore, tension meters 6 and 7 for measuring the tension of the rolled material M are provided between the entry reel 2 and the rolling mill 1, and between the delivery reel 3 and the rolling mill 1, respectively. The torque control devices 22 and 32 determine the torque (or current) of the electric motors 21 and 31 based on a tension control correction amount that controls the tension of the rolled material M at the entry and delivery sides of the rolling mill 1, measured by the tension meters 6 and 7, to a given tension target value.

[0026] On the delivery side of the rolling mill 1, there are installed a strip speed meter 8 that measures the speed of the rolled material M and a strip thickness meter 9 that measures the actual thickness of the rolled material M. Although not shown, if the rolling mill 1 is a reversible type, a strip speed meter and a strip thickness meter are also installed on the entry side of the rolling mill 1.

[0027] The cold rolling plant RP is operated by a control system using a computer. The computer includes a host computer 40 and a process control computer 41, which are connected to each other via a network. An interface screen 42, which is an operation screen for an operator, is connected to the process control computer 41 via the network. The operator can perform operations such as inputting control conditions on the interface screen 42.

[0028] The process control computer 41 executes setting calculation and control of the control object in a series of rolling processes. The process control computer 41 also has a function of controlling the screw down opening of the screw down device 114. The process control computer 41 receives from the host computer 40 the target thickness value (product thickness) h of the rolled material M. REF [mm] is entered.

[0029] The process control computer 41 calculates the target thickness h REF [mm] and the control conditions given from the interface screen 42. The process control computer 41 controls each piece of equipment appropriately based on the target thickness value h REF The process control computer 41 calculates the settings for each piece of equipment that can achieve this, and operates the actuators of each piece of equipment based on those settings. While each piece of equipment is operating, the operation of the actuators is 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 and adjusts the roll gap so that the measured thickness value (actual thickness) h of the rolled material M becomes the target thickness value (i.e., so as to cancel out the thickness deviation).

[0030] In this embodiment, when tension fluctuations occur due to reel eccentricity, controlling the electric motors 21, 31 to keep the tension constant has low responsiveness, so instead of such constant tension control, the device operates the highly responsive screw down device 114. A plate thickness control device having such characteristics will be described in detail below.

[0031] Fig. 2 is a schematic diagram showing the configuration of a process control computer 41, which is a strip thickness control device for a rolling mill according to an embodiment. Fig. 3 is a diagram for explaining division numbers assigned to the divided portions obtained by dividing the reels 2 and 3 at equal rotation angles. Fig. 4 is a diagram showing a first table Tb1 stored in the strip thickness deviation input determination unit. Fig. 5 is a diagram showing a second table Tb2 stored in the strip thickness deviation storage unit.

[0032] The process control computer 41 includes a movement distance calculation unit 411, a reel rotation angle calculation unit 412 (412a, 412b), a thickness deviation calculation unit 413, a thickness deviation input determination unit 414 (414a, 414b), a thickness deviation memory unit 415 (415a, 415b), a thickness deviation output determination unit 416 (416a, 416b), and an operation amount calculation unit 417 (417a, 417b).

[0033] In this embodiment, for the sake of simplicity, the first reel rotation angle calculation unit 412a and the second reel rotation angle calculation unit 412b will not be described individually, but will be described as a reel rotation angle calculation unit 412. The same applies to the thickness deviation input determination unit 414, the thickness deviation storage unit 415, the thickness deviation output determination unit 416, and the operation amount calculation unit 417.

[0034] The travel distance calculation unit 411 calculates the distance ΔL that the rolled material M has traveled during a calculation period Δt [sec] from the speed v [m / s] of the rolled material M measured by the strip speed meter 8, using the following formula (1): The calculation period Δt can be set according to the speed v [m / s] of the rolled material M, and can be set to, for example, 20 msec. ΔL=v×1000×Δt (1)

[0035] In addition, when the strip speed meter 8 is not installed on the delivery side of the rolling mill 1, or when the strip speed meter 8 cannot be used due to a malfunction or the like, the peripheral speed V of the work roll of the rolling mill 1 (hereinafter referred to as "roll peripheral speed") R The moving distance ΔL of the rolled material M may be calculated from the forward speed [m / s] and the forward slip ratio f by the following formula (2). ΔL=V R ×(1+f)×Δt (2)

[0036] 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 in-side reel 2, and sets the rotation angle value detected by the rotation angle detector 5 as the rotation angle of the out-side reel 3. When the rotation angle detectors 4 and 5 emit pulses according to the rotation of each of the 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 each of the reels 2 and 3, respectively.

[0037] The thickness deviation calculation unit 413 calculates the thickness measurement value h measured by the thickness meter 9. MEAS Based on [mm], thickness deviation Δh x [mm] is calculated using the following formula (3). Δh x =h MEAS -h REF ···(3)

[0038] In the above formula (3), h REF is the target thickness value [mm]. The thickness deviation Δh x If [mm] is transmitted, it can be used as is.

[0039] The thickness deviation input determination unit 414 determines the thickness deviation Δh calculated by the thickness deviation calculation unit 413. x The timing for inputting the thickness deviation data into the thickness deviation storage unit 415 is determined. As shown in FIG. 3, one rotation of each of the inlet reel 2 and the outlet reel 3 is divided into N equal rotation angles, and division numbers from 0 to N-1 are assigned in advance. As shown in FIG. 4, the thickness deviation input determination unit 414 has a first table Tb1 that can store N elements corresponding to the division number N (i.e., division number n) of each of the inlet reel 2 and the outlet reel 3. The first table Tb1 stores distances L0 to L1 that the part rolled by the rolling mill 1 has moved from the rolling mill 1 in association with the rotation angles of the inlet reel 2 and the outlet reel 3 when the rolled material M is rolled by the rolling mill 1, i.e., division number n (n=0 to N-1). N-1 I remember.

[0040] At the calculation timing (control cycle k), the thickness deviation input determination unit 414 adds the movement distance ΔL calculated by the movement distance calculation unit 411 to each element in the lower row of the first table Tb1 (see the following formula (4)). For example, if the rolled material M moves by 50 mm for each calculation cycle Δt, 50 mm is added to each element distance L0 to L1 at each calculation timing. N-1 The control period k may be the same as the calculation period Δt, or may be different from the calculation period Δt. Ln[k]=Ln[k-1]+ΔL[k] (4)

[0041] In the above equation (4), Ln[k] is the movement distance [mm] from the rolling mill 1 to the location of the rolled material M that was rolled at division number n in control cycle k, and ΔL[k] is the movement distance [mm] in control cycle k calculated by the movement distance calculation unit 411.

[0042] Next, the thickness deviation input determination unit 414 determines the input timing. Here, consider the time when input of the thickness deviation to division number n-1 in the thickness deviation storage unit 415 is completed. At this time, the thickness deviation input determination unit 414 checks whether division number n has reached the input timing. In other words, when the following formula (5) is satisfied, the thickness deviation input determination unit 414 determines that it is the input timing for division number n. Ln[k]≧L x ···(5)

[0043] In the above formula (5), L x is the distance between the rolling mill 1 and the thickness gauge 9 installed on the exit side of the rolling mill 1. If the above formula (5) is not satisfied, at the next calculation timing, it is checked again whether the input timing has been reached for division number n. This is repeated sequentially from division numbers 0 to N-1, and when division number N-1 has been reached, it returns to division number 0.

[0044] Furthermore, when the rotation angles of the inlet reel 2 and the outlet reel 3 calculated by the reel rotation angle calculation units 412a, 412b reach the rotation angle corresponding to the division number n, the thickness deviation input determination unit 414 clears the distance Ln from the rolling mill 1 corresponding to the division number n to zero.

[0045] By the above series of operations, it is possible to determine at which rotation angle the thickness measured by the thickness gauge 9 was rolled, which corresponds to which division number of the entry reel 2 and the delivery reel 3.

[0046] Incidentally, the operation of the thickness deviation input determination unit 414 described above does not take into account the delay in measurement by the thickness gauge 9. Therefore, depending on the degree of this delay, thickness control may become oscillatory. Therefore, it is preferable to compensate for the delay in measurement by the thickness gauge 9 as a first-order delay. Furthermore, delays occur due to signal transmission and calculation, and it is preferable to compensate for these delays as well. As a compensation method, instead of the above formula (5), the following formulas (6) and (7) are used for the inlet reel 2, and the following formulas (8) and (9) are used for the outlet reel 3 to determine the input timing.

[0047] Ln_ENT -(1 / 2)×D ENT ×φ ENT ×H / h≧L x ···(6) φ ENT =tan -1 (ω ENT ×T x )+ω ENT ×T d ···(7) L n_DEL -(1 / 2)×D DEL ×φ DEL ≧L x ···(8) φ DEL =tan -1 (ω DEL ×T x )+ω DEL ×T d ···(9)

[0048] In the above formulas (6) to (9), L n_ENT ,L n_DEL is the distance [mm] traveled from the rolling mill 1 to the point where the entry reel 2 was rolled when the division number was n, and the distance [mm] traveled from the rolling mill 1 to the point where the exit reel 3 was rolled when the division number was n. D ENT ,D DEL is the coil diameter [mm] of the rolled material M wound around the inlet reel 2 and the outlet reel 3, H is the inlet plate thickness [mm], and h is the outlet plate thickness [mm]. T x is the thickness gauge time constant [s], and ω ENT ,ω DEL is the rotational angular velocity [rad / s] of the inlet reel 2 and outlet reel 3.

[0049] Here, the rotational angular velocity ω of the inlet reel 2 and outlet reel 3 is ENT ,ω DEL [rad / s] can be obtained, for example, by taking the difference in the rotation angle calculated by the reel rotation angle calculation unit 412. By compensating for the delay in measurement by the thickness gauge 9 as described above, the accuracy of thickness control can be improved.

[0050] The thickness deviation storage unit 415 has a structure similar to that of the thickness deviation input determination unit 414. As shown in FIG. 5, the thickness deviation storage unit 415 has a second table Tb2 that can store N elements corresponding to the division number N (i.e., division number n) of each of the inlet reel 2 and the outlet reel 3. The second table Tb2 stores an integrated value of the thickness deviation to which the thickness deviation calculated by the thickness deviation calculation unit 413 based on the input timing determined by the thickness deviation input determination unit 414 is added, in association with the rotation angle of the inlet reel 2 and the outlet reel 3 when the rolled material M is rolled by the rolling mill 1, i.e., division number n (n = 0 to N-1). For example, when the input timing of division number n is reached, the thickness deviation storage unit 415 calculates the following equation (10) and stores the calculation result in the lower section of the second table Tb2 as a new integrated value of the thickness deviation for division number n. Δh n [k]=λ×Δh n [k-1]+Δh x [k] (10)

[0051] In the above formula (10), Δh n [k] is the integrated value [mm] of the thickness deviation for division number n in control cycle k, λ is the forgetting factor that takes a value between 0 and 1, and Δh x [k] is the thickness deviation [mm] in the control cycle k calculated by the thickness deviation calculation unit 413.

[0052] Here, when the forgetting factor λ is set to 1, the thickness deviation in control cycle k and the thickness deviations stored (already stored) before control cycle k (k-1, k-2, ...) are stored with equal weight. On the other hand, by multiplying the thickness deviations stored before control cycle k by the forgetting factor λ, the weight of the thickness deviations stored before control cycle k can be reduced. For example, in cases where the correspondence between the division number (rotation angle) and the thickness deviation measurement location shifts over time, setting the forgetting factor λ to a value smaller than 1 can reduce the weight of thickness deviations measured in the past, which is advantageous in that it can improve the accuracy of thickness control.

[0053] The thickness deviation output determination unit 416 determines the timing for outputting the integrated value of the thickness deviation from the thickness deviation storage unit 415. That is, the thickness deviation output determination unit 416 determines that the output timing for the integrated value of the thickness deviation corresponding to the division number is when the rotation angles of the input reel 2 and the output reel 3 calculated by the reel rotation angle calculation unit 412 become rotation angles corresponding to the division number.

[0054] At this time, it is preferable that the thickness deviation output determining unit 416, like the thickness deviation input determining unit 414, compensates for the response delay of the screw down device 114 by regarding the response delay of the screw down device 114 as a first-order delay. For example, the output timing for division number n is determined for the inlet reel 2 using the following equations (11) and (12), and for the outlet reel 3 using the following equations (13) and (14), respectively. θ ENT +φ ENT ≧θ n ···(11) φ ENT ≧tan -1 (ω ENT ×T H )···(12) θ DEL +φ DEL ≧θ n ···(13) φ DEL ≧tan -1 (ω DEL ×T H )···(14)

[0055] In the above formulas (11) to (14), θ ENT ,θ DEL is the rotation angle of the incoming reel [rad], the rotation angle of the outgoing reel [rad], and θ n is the rotation angle [rad] corresponding to the division number n. H is the time constant [s] of the screw down device 114, and ω ENT ,ω DEL is the rotational angular velocity [rad / s] of the inlet reel 2 and outlet reel 3.

[0056] The operation amount calculation unit 417 calculates the correction amount for the screw gap opening control device 115 based on the output timing determined by the plate thickness deviation output determination unit 418. For example, when the output timing is for 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 screw gap opening control device 115. ΔS={K×M / (M+Q)×Δh n}···(15)

[0057] In the above formula (15), ΔS is the amount of operation of the screw down 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 plasticity coefficient [kN / mm] of the rolled material M, and Δh n is the integrated value [mm] of the thickness deviation of division number n.

[0058] Here, the effect of eccentricity of the reels 2, 3 is large when the coil diameter (also referred to as coil diameter) of the rolled material M wound around the reels 2, 3 is small, and gradually decreases as the coil diameter increases. Therefore, as shown in Figure 6, it is preferable to set the adjustment coefficient K in advance in accordance with changes in the coil diameter, obtain the adjustment coefficient K corresponding to the coil diameter when calculating the roll gap opening manipulated variable ΔS, and adjust the manipulated variable ΔS using (multiplying by) the obtained adjustment coefficient K. According to this, when the coil diameter is small, the strip thickness control effect by the manipulated variable ΔS can be increased, and when the coil diameter is large, the roll gap opening manipulated variable ΔS can be suppressed to prevent it from becoming a disturbance to the strip thickness control.

[0059] Furthermore, the operation amount calculation unit 417 may be configured to set upper and lower limit values ​​as shown in the following equation (16) for the operation amount (correction amount) ΔS of the roll down opening control device 115 calculated by the above equation (15), and to set the operation amount ΔS to the upper or lower limit value when this range is exceeded. ΔS LL ≦ΔS≦ΔS UL ···(16)

[0060] In the above formula (17), ΔS LL is the lower limit, and ΔS ULis the upper limit value. When the calculated manipulated variable ΔS is lower than the lower limit value ΔS LL When the operating amount ΔS falls below the lower limit ΔS LL and the upper limit ΔS UL When the operation amount ΔS exceeds the upper limit value ΔS UL According to this, although the operation amount ΔS is limited and the plate thickness deviation remains, by preventing fluctuations in the control of the roll gap, stable rolling by the rolling mill 1 can be realized.

[0061] Incidentally, when the screw down device 114 is operated, the tension on the entry side and delivery side of the rolling mill 1 changes. This increases the deviation between the tension measured by the tension meters 6 and 7 and the target tension value. If tension control is performed so that the measured tension becomes the target tension value (i.e., if excessive tension control is performed to eliminate the deviation), there is a risk of adversely affecting the thickness of the strip on the delivery side of the rolling mill 1 (deteriorating the accuracy of thickness control). To prevent this, the manipulated variable calculation unit 417 calculates a correction amount for the target tension value in accordance with the manipulated variable ΔS of the roll down aperture, and corrects the target tension value. As a result, the deviation between the corrected target tension value and the target tension value becomes smaller than before the correction, and excessive tension control is not performed, preventing adverse effects on the thickness of the strip on the delivery side of the rolling mill 1. In this case, as with the manipulated variable ΔS of the roll down aperture of the screw down device 114, upper and lower limits may be set for the correction amount of the target tension value, and correction may be performed within that range. Here, the relationship between the manipulated variable ΔS of the roll gap opening and the change in tension can be set in advance by, for example, changing the roll gap opening of the roll gap device 114 through an experiment and measuring the change in tension at that time, or by determining the correlation between the change in roll gap opening (ΔS) and the change in tension through a simulation.

[0062] The specific structure of the process control computer 41 is not limited, and may be as follows, for example. FIG. 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 the processing circuit shown in FIG. 7. This processing circuit may be dedicated hardware 41a. This processing circuit may include a processor 41b and a memory 41c. This processing circuit may be partially formed as dedicated hardware 41a, and may further include a processor 41b and a memory 41c. In the example of FIG. 7, part of the processing circuit is formed as dedicated hardware 41a, and the processing circuit also includes a processor 41b and a memory 41c.

[0063] At least a portion of the processing circuitry may be at least one dedicated hardware 41a, such as a single circuit, a multiple circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

[0064] The processing circuit may include at least one processor 41b and at least one memory 41c. In this case, each function of the process control computer 41 is realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in the memory 41c. The processor 41b realizes the functions of each part of the plate thickness control device 41 by reading and executing the programs stored in the memory 41c.

[0065] The processor 41b is also called a CPU (Central Processing Unit), central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP. The memory 41c corresponds to, for example, a non-volatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, or EEPROM.

[0066] In this way, the processing circuit can realize each function of the process control computer 41 by hardware, software, firmware, or a combination of these.

[0067] As described above, according to the present disclosure, the thickness of the strip at the delivery side of the rolling mill 1 is measured by the thickness gauge 9, and the thickness deviation between the measured thickness and the target thickness value is associated with the rotation angle of the reels 2, 3, thereby making it possible to extract periodic thickness fluctuations due to reel eccentricity (the effect on the thickness at the delivery side of the rolling mill 1). A correction amount for the screw down aperture control device 115 is calculated from the thickness fluctuations extracted according to the rotation angle of the reels 2, 3, and the screw down device 114, which has a faster response than the speed control system of the conventional example, is operated. As a result, even if the tension of the rolled material M varies due to reel eccentricity caused by winding on the reels 2, 3, the effect of reel eccentricity on the thickness of the rolled material M at the delivery side of the rolling mill 1 can be reduced, and as a result, good thickness accuracy at the delivery side of the rolling mill 1 can be maintained.

[0068] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments and can be implemented in various modifications without departing from the spirit of the present disclosure. When the numbers, quantities, amounts, ranges, etc. of each element are mentioned in the above embodiments, the present invention is not limited to the mentioned numbers unless otherwise specified or clearly specified in principle. Furthermore, the structures, etc. described in the above embodiments are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

[0069] In the above embodiment, the thickness deviation input determination unit 414 compensates for the measurement delay of the thickness gauge 9 and the delay due to signal transmission and calculation, and the thickness deviation output determination unit 416 compensates for the response delay of the screw down device 114, but this is not limited to this. The thickness deviation input determination unit 414 may compensate for the measurement delay of the thickness gauge 9, and the thickness deviation output determination unit 416 may compensate for the response delay of the screw down device 114 and the delay due to signal transmission and calculation, and in this case, the same effects as those of the above embodiment can be obtained. Furthermore, the thickness deviation input determination unit 414 may collectively compensate for the measurement delay of the thickness gauge 9, the response delay of the screw down device 114, and the delay due to signal transmission and calculation, in this case, in addition to obtaining the same effects as those of the above embodiment, software design can be simplified. Furthermore, the thickness deviation output determination unit 116 may collectively compensate for the measurement delay of the thickness gauge 9, the response delay of the screw down device 114, and the delay due to signal transmission and calculation. It is possible to compensate for at least one of the delay in measurement by the thickness gauge 9, the delay in signal transmission and calculation, and the response delay of the screw down device 114 of the rolling mill 1.

[0070] In the above embodiment, the movement direction of the rolled material M is described as being from left to right as indicated by the arrow in Figure 1, but this is not limited to this, and the present disclosure can also be applied when the movement direction is the opposite (from right to left).

[0071] Furthermore, in the above embodiment, the torque control of the electric motors 21, 31 of the reels 2, 3 has been described as an example, but the present disclosure can also be applied to the case of speed control.

[0072] Furthermore, in the above embodiment, an example has been described in which a four-high rolling mill (a rolling mill having four rolls 111, 112) 1 is used, but the rolling mill 1 is not limited to this. In the above embodiment, an example has been described in which the rolling mill 1 includes one rolling stand 11, but the rolling mill 1 may include two or more rolling stands. In this case, similar to the above embodiment, it is sufficient to calculate the manipulated variable ΔS of the reduction opening of the reduction device of each rolling stand. [Explanation of symbols]

[0073] 1... rolling mill, 114... screw down device, 2... inlet reel, 3... outlet reel, 4, 5... rotation angle detector, 6, 7... tension meter, 8... strip speed meter, 9... strip thickness meter, 41... strip thickness control device, process control computer, 411... travel distance calculation unit, 412... reel rotation angle calculation unit, 413... strip thickness deviation calculation unit, 414... strip thickness deviation input determination unit, 415... strip thickness deviation memory unit, 416... strip thickness deviation output determination unit, 417... operation amount calculation unit, M... rolled material

Claims

1. A plate thickness control device for a rolling mill, A thickness gauge is installed on the delivery side of the rolling mill, a tension meter is installed on at least one of the entry side and delivery side of the rolling mill, and a reel motor is controlled so that the tension measured by the tension meter becomes a target tension value, a movement distance calculation unit that calculates a distance that the rolled material rolled by the rolling mill has moved from the rolling mill; a reel rotation angle calculation unit that calculates the rotation angle of the reel and is installed on at least one of the entry side and the exit 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 plate thickness meter; A thickness deviation input determination unit that determines the input timing of the thickness deviation based on 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; A thickness deviation storage unit that adds and stores the thickness deviation calculated by the thickness deviation calculation unit based on the input timing determined by the thickness deviation input determination unit; a thickness deviation output determination unit that determines the timing of outputting the thickness deviation based on the rotation angle of the reel calculated by the reel rotation angle calculation unit; An operation amount calculation unit that reads out the integrated value of the thickness deviation stored in the thickness deviation storage unit based on the output timing determined by the thickness deviation output determination unit, and calculates the operation amount of the reduction device of the rolling mill based on this integrated value; and configured to operate the screw down device based on the operation amount of the screw down device calculated by the operation amount calculation unit, The plate thickness control device for a rolling mill is configured so that the operation amount calculation unit calculates a correction amount for the tension target value based on the operation amount of the screw down device.

2. 2. The plate thickness control device for a rolling mill according to claim 1, further comprising a plate speed meter on the delivery side of the rolling mill, The travel distance calculation unit is a plate thickness control device for a rolling mill that calculates the travel distance of the rolled material rolled by the rolling mill based on the speed of the rolled material measured by the plate speed meter.

3. 2. 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 determine the input timing and the output timing, respectively, by compensating for at least one of a delay in measurement by the plate thickness gauge, a delay due to signal transmission or calculation, and a response delay of a reduction device of the rolling mill.

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

5. 2. 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 a coil diameter of the rolled material wound around the reel when calculating the operation amount of the screw down device, and to adjust the operation amount using the obtained adjustment coefficient.

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