JP2014028387A - Rolling control device, plant control device and rolling control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the oscillation of control such as tension control which uses a rolling mill speed as a final control element, even when a control gain is large.SOLUTION: A rolling control device controls a tandem rolling mill in which a plurality of pairs of rolls are used to roll a material to be rolled. According to the deviation of a state quantity measured between adjacent pairs of rolls, the rolling control device controls the rotational speed of a pair of rolls arranged on the upstream side, of the adjacent pairs of rolls, and the rotational speed of a pair of rolls arranged on the further upstream side. The rolling control device detects the oscillation of the state quantity measured between the adjacent pairs of rolls, and changes a control response in the control of the rotational speed of the pair of rolls arranged on the upstream side, of the adjacent pairs of rolls between which the oscillation is detected.

Description

  The present invention relates to a rolling control device, a plant control device, and a rolling control method, and more particularly to suppression of control oscillation when a control gain is large.

  In a hot tandem rolling mill, the tension and rolling load applied to the material to be rolled, and the rolling mill outlet side thickness are controlled using the roll gap, which is the distance between the upper and lower work rolls, and the roll speed of the equipment before and after the rolling mill. The rolling operation is performed. Between the rolling mill stands, a looper for supporting a material to be rolled between the stands is installed. By changing the support state of the material to be rolled by the looper, the tension applied to the material to be rolled changes, so that the tension of the material to be rolled can be detected by measuring the pressure applied to the looper. As for the looper, the constant height control is performed by the proportional integral control by the pressure by the hydraulic cylinder.

  The plate thickness control is a set value in which the plate thickness on the delivery side of the rolling mill is determined in advance using the detection result of the thickness meter or the estimated thickness value from the rolling load and the roll gap. Control to be. Tension control is necessary to prevent the material to be rolled from sagging between the stands of the rolling mill or to reduce the sheet width due to over tension. Control is implemented.

  In a general hot tandem rolling mill, the plate thickness is controlled by adjusting the roll gap of each stand, and the tension is controlled by adjusting the roll speed on the front side of the adjacent stand roll. Further, as the tension detecting means, the tension received by the looper from the material to be rolled is detected from the pressure applied to the load cell or the hydraulic cylinder of the looper.

  In a tandem rolling mill in which a plurality of rolling stands are arranged in series, when the i-th roll speed is adjusted, both the tension between the i-1th and the tension between the i + 1th are affected. Such an effect may cause oscillation due to interference of tension control between the stands, leading to deterioration of plate pressure accuracy. In order to solve such a problem, there is a method of correcting the gap between rolls according to the upstream tension results and setting response speeds of tension control means installed between adjacent rolling stands to different characteristics. It is already known (see, for example, Patent Document 1).

JP-A-5-15913

  In a hot tandem rolling mill, since a material to be rolled having various product specifications is rolled, it is necessary to set a control gain according to the product specifications. On the other hand, there is a problem that the control gain setting error is large because the rolling phenomenon model and the parameters of the rolling phenomenon model such as the deformation resistance, the friction coefficient, and the plate temperature used in the model calculation are inaccurate.

  In a tandem rolling mill, the roll speed of each rolling mill is controlled by a speed control device. When roll speed is used as the operation end of tension control, the tension control system is designed taking into account the response of the speed control system including the speed control device and the rolling mill. When the gain is set to be large or when a high control gain is set to improve the control response, the control may vibrate due to the response of the speed control system. This is because the speed control system is simply approximated as a second-order lag system, but has a resonance frequency.

  In that case, when the tension control system performs control stepwise in response to a large tension disturbance, the vibration at the resonance frequency continuously remains (oscillation) or the vibration amplitude gradually increases ( Divergence, hereinafter included in oscillation). In addition, when there is a tension disturbance (for example, hardness variation of the material to be rolled or mechanical vibration of the rolling mill) having a frequency component near the resonance frequency, the tension variation may increase.

  Therefore, it takes a lot of time to adjust the tension control, such as when starting a new hot tandem rolling mill or starting production of a new product, resulting from control failure caused by excessive or insufficient control gain. There was a problem that the rolling operation was stopped and product defects occurred.

  The technique disclosed in Patent Document 1 is a method for suppressing oscillation in advance, and is not suitable as a method for suppressing oscillation when it occurs. The above-described problem is not limited to a tandem rolling mill, but is a plant control that repeats the same type of control as in a tandem rolling mill, and the control amount of a certain control point is changed. If it affects the control of the previous control point, it can be a problem as well.

  The present invention addresses the above-described problems, and an object of the present invention is to suppress the oscillation of control using the rolling mill speed as an operation end, such as tension control, even when the control gain is large.

  One aspect of the present invention is a rolling control device that controls a tandem rolling mill that rolls a material to be rolled with a plurality of pairs of rolls, and a roll corresponding to a measurement position based on a deviation of a measured state quantity and its A roll speed control unit that controls the rotation speed of a roll arranged on the upstream side or the downstream side, an oscillation detection unit that detects oscillation of a state quantity to be measured, a roll according to the measurement position where the oscillation is detected, and An oscillation control unit that changes a control response in the control of the rotational speed of the same roll as the control of the rotational speed based on the deviation of the state quantity among the rolls arranged on the upstream side or the downstream side thereof. And

  Another aspect of the present invention is a plant control apparatus that controls a plant that repeats the same type of processing in a plurality of control objects, and the control object according to the measurement position based on the deviation of the measured state quantity and A state control unit that changes the control state of the control object on the upstream side or the downstream side, an oscillation detection unit that detects oscillation of a state quantity to be measured, a control target in which oscillation is detected, and an upstream or downstream side of the control target An oscillation control unit that changes a control response in a change in the control state of the same control target as the change in the control state based on the state quantity deviation among the control targets is included.

  Still another aspect of the present invention is a rolling control method for controlling a tandem rolling mill that rolls a material to be rolled with a plurality of pairs of rolls, and based on a deviation of a measured state quantity, depending on a measurement position. The rotation speed of the roll and the roll arranged upstream or downstream thereof is controlled, the oscillation of the state quantity to be measured is detected, and the roll corresponding to the measurement position where the oscillation is detected and the upstream or downstream thereof Among the rolls arranged on the side, the control response in the control of the rotational speed of the same roll as the control of the rotational speed based on the deviation of the state quantity is changed.

  By using the present invention, even when the control gain is large, it is possible to suppress the oscillation of the control using the rolling mill speed as the operation end, such as tension control.

It is a figure showing the whole rolling device composition concerning the embodiment of the present invention. It is a figure which shows operation | movement of the looper in the rolling apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of the feedback control in a general rolling apparatus. It is a figure which shows the frequency response of the control gain in a general rolling apparatus. It is a figure which shows the convergence, oscillation, and divergence of the state quantity by the difference in control gain. It is a figure which shows the structure of the speed control system which concerns on a prior art and embodiment of this invention. It is a figure which shows the example of the step response of a speed control system. It is a figure which shows the example of the closed loop response of a speed control system. It is a figure which shows the example of a phase shift and an amplitude change. It is a figure which shows the Bode diagram of the example of control of tension control between stands. It is a figure which shows the example of the suppression aspect of the oscillation state of tension control between stands. It is a figure which shows the example when there exists disturbance of a resonant frequency. It is a figure which shows the control structure of the tandem rolling mill which concerns on a prior art. It is a figure which shows the structure of the stand speed determination apparatus which concerns on a prior art. It is a figure which shows the structure of tension control between stands concerning a prior art. It is a figure which shows the structure of the speed control system which concerns on embodiment of this invention. It is a figure which shows the control structure of the tandem rolling mill which concerns on embodiment of this invention. It is a figure showing the composition of tension control between stands concerning the embodiment of the present invention. It is a flowchart which shows the operation | movement of the speed response adjustment which concerns on embodiment of this invention. It is a figure which shows the adjustment aspect of the speed response which concerns on embodiment of this invention. It is a figure which shows the adjustment aspect of the speed response which concerns on embodiment of this invention. It is a figure showing the hardware constitutions of tension control between stands concerning the embodiment of the present invention.

Embodiment 1 FIG.
Hereinafter, an embodiment of the present invention will be described taking tension control between rolling mill stands in a hot rolling mill as an example. FIG. 1 is a diagram showing a tension control system according to the present embodiment. As shown in FIG. 1, the inter-stand tension control unit 10 applies a tension applied to the material to be rolled 8 between the i-1 stand rolling mill 1 and the i stand rolling mill 2 of the hot tandem rolling mill to the looper 7. The roll speed of the i-1 stand rolling mill 1 is controlled by detecting the tension meter 9 installed and changing the speed command for the i-1 stand speed controller 11.

  The looper 7 has a looper arm 15 that can be rotated around a looper fulcrum 14 in a mechanically fixed position, and a hydraulic pressure for changing the position of the looper roll 16 by rotating the looper arm 15 around the looper branch 14. It comprises a cylinder 13 and a cylinder position detector 17 for detecting the cylinder position. The looper roll 16 receives tension applied to the material to be rolled 8 by pushing up the material 8 to be rolled. By measuring the force applied to the looper roll 16 with the tension meter 9, the inter-stand tension control unit 10 acquires the tension applied to the material 8 to be rolled.

  2A and 2B show the operation of the looper 7. When the material to be rolled tip 30 is between the i-1 stand rolling mill 1 and the i stand mill 2, the looper roll 16 collides with the material to be rolled 30 and the machine is damaged. As shown to Fig.3 (a), it waits in the position lower than the passage position of the to-be-rolled material 8. FIG. When the workpiece 30 reaches the i-stand rolling mill 2, the looper roll 16 moves to a position where the workpiece 8 is lifted as shown in FIG. The tension can be measured with the tension meter 9.

  Since the tension of the material 8 to be rolled is transmitted from the looper roll 16 to the hydraulic cylinder 13 via the looper arm 15, when the tension of the material 8 to be rolled fluctuates, a difference occurs between the pressure of the hydraulic cylinder 13 and the cylinder position changes. To do. As a result, the position of the looper roll 16 changes. Since the position fluctuation of the looper roll 15 becomes a tension fluctuation and affects the stability of the rolling operation, looper position control is performed to keep the position constant. The looper position control device 20 controls and controls the pressure of the hydraulic cylinder 13 using the cylinder position measured by the cylinder position detector 17 so that the position of the looper roll 16 is constant.

  FIG. 3 is a block diagram showing a configuration of tension control between stands in a conventional hot tandem rolling mill. The inter-stand tension control unit 10 outputs a control command to the i-1 stand speed control device 11 so as to remove the deviation between the tension command and the actual tension using proportional integral control, and the i-1 stand roll speed. To change. When the i-1 stand roll speed is changed, the actual tension is changed by the speed-tension response 31. This change is detected by the tension meter 9 and used as the actual tension.

  The fluctuation of the actual tension results in the fluctuation of the hydraulic cylinder 13 due to the plate tension-cylinder pressure 32 which is a mechanical system. When the pressure of the hydraulic cylinder 13 fluctuates, the cylinder position changes, and the looper mechanical system 35 causes the looper position to change. The inter-stand plate path length varies depending on the fluctuation, that is, the looper position-the inter-stand plate path length 34.

The plate length variation between the stands becomes a tension variation due to the plate length change-tension response 33, and the actual tension changes. Here, the speed-tension response 31 is expressed by the following formula (1), and the plate path length change-tension response 33 is expressed by the following formula (2).

The speed-tension response 31 and the plate path length change-tension response 33 are due to a rolling phenomenon, and change depending on the material, sheet thickness, rolling speed, and the like (hereinafter referred to as a rolling schedule) of the material 8 to be rolled. Conversely, if these values are known, the response of the i-1 stand speed control device 11 can be approximated by a second-order lag system by the following equation (3).

  Since the response of the i-1 stand speed control device 11 according to the above formula (2) does not depend on the rolling schedule, the control gain of the inter-stand tension control unit 10 can be set as shown in FIG.

In general, it is considered that the order of T _sigma is the order of a few ms, 1 / T _sigma is greater than the response omega _n of the speed control system. Thus, Bode diagram of the loop transfer function to become as shown in FIG. 4, to set the crossover frequency at ω ≦ 1 / T _I. Here, assuming that ω _c = α / T _I (where α ≦ 1.0), the following equation (4) is established.

Accordingly, the gain K _P of the inter-stand tension controller 10 is expressed by the following equation (5).

Obtained in FIG. 4 shows a control response simulation result when the control gain K _P of the interstand tension controller 10 in accordance with the rolling schedule is excessive in FIG 5 (a) ~ (c) . 5A to 5C show control responses when a tension deviation disturbance (tension disturbance) is applied stepwise. FIG. 5A shows a control gain of 5 times and FIG. FIG. 5B shows a case where the actual tension is oscillated (vibrates while the amplitude is constant) 10.35 times, and FIG. 5C shows a case where the actual tension is 20 times the control gain diverges due to vibration.

From the above, when the response of the speed control system is approximated by a second-order lag system, the tension variation between the stands of the hot tandem rolling mill may oscillate or diverge when the control gain exceeds 10 times. I understand. The _KσV in the speed-tension response 31 differs depending on the rolling schedule, and it can be predicted that the difference may be larger than 10 times. Therefore, even when the control gain setting has an error, it can be stably controlled. A control method is required.

  6A and 6B are block diagrams of a speed control system which is the i-1 stand speed control apparatus 11 approximated by a second-order lag system in FIG. FIG. 6A is a block diagram of a normal speed control system. An FB-ASR (Feedback Automatic Speed Regulator) 900 outputs a current command to an ACR (Automatic Current Regulator) 901 by proportional-integral control based on the deviation between the speed record and the speed command. In the ACR 901, control is performed so that the actual current flowing through the electric motor 902 matches the current command.

  The ACR 901 is actually an FB control that matches the current command and the current performance, but the control response is sufficiently faster than the response of the FB-ASR 900, and can be approximated by a first-order lag system. The electric motor 902 converts the current into torque from the current-torque conversion coefficient ζφ, and changes the rolling mill speed according to the moment of inertia J of the rolling mill roll.

FIG. 6B is a diagram showing a speed control system block diagram in the case where an FF-ASR (Feed Forward ASR) 903 is provided. FF-ASR 903 includes FF-ASR command compensation 904 and FF-ASR current compensation 905. In FF-ASR directive compensation 904, by placing the first-order lag of time constant _{T FF} on the speed command, a first-order lag and response according to the time constant _{T FF.} In FF-ASR current compensation 904, with respect to the speed command containing the first-order lag time constant T _FF, the acceleration and deceleration current command corresponding thereto, to create the differential conversion gain T _M. If the operation of the FF-ASR current compensation 905 is appropriate, the speed command to the FB-ASR 900, which is the output of the FF-ASR command compensation 903, matches the speed record, so the FB-ASR 900 hardly operates (current control) Some operations occur due to system dead time).

FIGS. 7A to 7D are diagrams showing step responses of the speed control system. FIG. 7A shows a response when a normal speed control system is used. Here, in the control response of the FB-ASR 900, the gain crossover frequency ω _c of the loop transfer function is set to ω _c = 20 [rad / s]. The broken line indicates the speed command given in a step shape, the solid line indicates the speed result that is the control result of the speed control system, and the alternate long and short dash line indicates the case where the primary delay system set at ω _FF = 20 [rad / s] is included in the speed command Speed command. This is the same as the output of the FF-ASR speed compensation 904 in the speed control system with FF-ASR.

  FIG. 7B shows the response when the FF-ASR 903 is provided and the result when the FF-ASR current compensation 905 is implemented 100%. In this case, the speed record can be matched with the output of the FF-ASR speed compensation 904. FIG. 7C shows a response when the FF-ASR current compensation 905 is not performed (0% compensation amount). The response becomes worse because the stepped speed command becomes the first order lag system by the FF-ASR command compensation 904. FIG. 7D shows a step response when the response of FF-ASR is ωFF = 40 [rad / s]. Since the FF-ASR current compensation 905 is performed 100%, the control response matches the first order lag of 40 [rad / s].

8A to 8D show Bode diagrams of the closed loop response of the speed control system corresponding to FIGS. 7A to 7D. It is possible to change the response of the speed control system by changing the gain ω _{FF of} the FF-ASR 903 or the gain of the FF-ASR current compensation 905.

  With respect to the control output of the inter-stand tension control 10 in FIG. 3, the phase delay and magnitude are converted by the frequency by the i-1 stand speed control device 11, and the tension result becomes the tension fluctuation amount by the control in the speed-tension response 31. To correct. The tension fluctuation amount by the control with respect to the actual tension results in a phase shift that varies depending on the frequency, but the resonance point is determined by the balance between the phase shift and the actual speed fluctuation attenuation with respect to the speed command.

  FIG. 9 shows how Δy becomes relative to Δx as a result of subtracting a gain obtained by giving a sine wave as Δx and adding a phase difference to Δx. In FIG. 9, the solid line indicates a gain of 1.0, the broken line indicates a gain of 0.5, and the dotted line indicates a gain of 0.3. As the phase shift increases, the amplitude of Δy increases. For example, when the phase difference is 180 degrees and the gain is 1 time, Δy is doubled. Even if the control deviation Δx is to be removed due to the relationship between the gain and the phase, Δy may increase as a result. Even if the phase difference increases, Δy decreases as the gain decreases.

  For the tension control of the hot tandem rolling mill shown in FIG. 3, the speed control device shown in FIGS. 7 (a) to (d) and FIGS. 8 (a) to (d) is used as the i-1 stand speed control device 11. FIG. 10 shows a Bode diagram of tension control in the case of the occurrence of the tension. The control gain of the inter-stand tension control 10 is constant. By changing the response of the FF-ASR 903, the frequency characteristic of the tension control between the stands can be changed. Accordingly, the resonance point also varies.

  As described above, even if the response of the FB-ASR 900 is constant, the frequency of the resonance point can be changed by changing the response of the FF-ASR 903 that is a response to the control output of the inter-stand tension control 10. When this is used, it is possible to suppress the tension control between the stands that oscillates at the resonance point.

  The tension control 10 between the stands of the hot tandem rolling mill shown in FIG. 3 is set to a gain at which the tension deviation oscillates and oscillates in a step response. An example in which the gain is changed from 0 to 0.1 is shown in FIG. It can be seen that by changing the gain of the FF-ASR current correction, the oscillation state has been eliminated because the resonance frequency has shifted.

  FIG. 12 shows an example when a tension disturbance between the stands of the resonance frequency component occurs. In FIG. 12, the tension disturbance is increased by the inter-stand tension control 10. In this case, when the FF-ASR current correction is changed from 0% to 100%, the resonance frequency shifts, and thus a control effect can be obtained. In this case, the control effect is obtained because the resonance frequency is shifted in the direction of increasing, but the tension disturbance is not increased (the control effect is attenuated) even when the resonance frequency is shifted down. If a problem occurs when the resonance frequency is shifted in the higher direction (such as approaching the resonance frequency of the mechanical system), the resonance frequency may be shifted in the direction of decreasing.

  FIG. 13 shows an inter-stand tension control system for a 4-stand tandem rolling mill as an example of a hot tandem rolling mill. As shown in FIG. 13, # 1 to # 4 stand rolling mills 801 to 804, # 1 to # 4 stand speed control devices 811 to 814, # 1 to # 2 stand tension meter 841, and # 2 to # 3 stands The inter-stand tension control 831 to 833 is performed on the rolling mill constituted by the tensiometer 842 and the # 3- # 4 inter-stand tension meter 843.

The i-1 stand speed control device 11 described in FIG. 6A corresponds to # 1 to # 4 stand speed control devices 811 to 814 in FIG. In speed reference setting device 850, it determines the speed _{V R4} of the fourth stand rolling mill 804. As a determination method, manual operation by an operator or automatic acceleration / deceleration according to the rolling state can be considered.

In a rolling mill, since the exit side plate thickness is different in each rolling mill stand, the rolling speed is different in each stand. Since the thickness of the outlet side of each rolling mill stand and the tension setting between the stands are determined by the product specifications of the material to be rolled, the advance rate of each rolling mill stand is determined according to the rolling model and is used to determine each stand speed determining device 821. In ~ 823, the calculation as shown in FIG. 14 is performed to determine the speed setting value V _Ri0 for each stand. Here, h _i shown in FIG. 14 indicates the outlet side plate pressure of the #i stand, and f _i indicates the advanced rate of the #i stand.

As shown in FIG. 15, the tension control between the stands 831 to 833 includes the actual tensions T _12fb , T _23fb and T _34fb from the inter-stand tension meters 841 to ₈₄₃ , and the set tension targets T _12ref , T _23ref and T _34ref. The ATR (tension control) speed command is obtained by proportional integral control. Here, each tension target described above is set by the tension reference generator 851 by a predetermined method such as table lookup or model calculation according to the product specifications of the material to be rolled.

In a tandem rolling mill, it is important that the speed ratio V _Ri / V _{Ri + 1} of each rolling mill stand does not fluctuate even if V _R4 changes due to acceleration / deceleration. Based on this, a value such as the following equation (6) is output as a tension control command. In this way, the tensile force control command output is the roll stand speed reference _{V Ri0} and respectively multiply and eventually speed command _V R1ref to each roll _{stand, V R2ref, V R3ref, V} R4ref is determined The

For example, when # 2-3 stand tension control changes the # 2 rolling mill stand speed, the speed ratio V _R1 / V _{R2 of the} # 1 rolling mill stand and the # 2 rolling mill stand is prevented from fluctuating accordingly. Therefore, the # 1 rolling mill stand speed is also changed at the same ratio. If it does in this way, the relationship of the following formulas (7) will be realized.

  As a result, the ratio between the # 1 rolling mill stand speed and the # 2 rolling mill stand speed does not change, which affects the tension between the # 1 rolling mill stand and the # 2 rolling mill stand and the # 2 rolling mill stand exit side plate thickness. Does not occur. This is called successful. In the 4-stand tandem rolling mill, there is a successive 835 of control output of # 3-4 inter-stand tension control 833 and a successive 836 of control output of # 2-3 inter-stand tension control 832. There are cases where the succession is not implemented.

In summary, the speed commands to the speed control devices 811 to 814 of each rolling mill stand are represented by the following equations (8) to (11).

  The speed command to each of the rolling mill stand speed control devices 811 to 814 is obtained by multiplying three types of speed reference, stand tension control command, and successive. As described above, the response of the FF-ASR 903 is changed only for the tension control command between the stands to shift the resonance frequency of the speed control system, and the speed reference is common to each rolling mill stand. The response should be the same as the response to the tension control output between the stands.

  For example, # 3-4 inter-stand tension control output succession is performed for # 1 stand and # 2 stand, but this is done according to the speed control system response of # 3-4 stand tension control output. The # 2-3 stand tension control output succession is performed for the # 1 stand, which is performed in accordance with the speed control system response of the # 2-3 stand tension control output.

FIG. 16 shows the configuration of the speed control system in the present invention for realizing this. When considering a 4-stand tandem rolling mill, in # 1 stand, the # 3-4 tension for the tension control between the stands, the # 2-3 the tension for the tension control between the stands, and the # 1-2 stand tension control output It is necessary to input three control commands ΔV ₁ , ΔV ₂ , ΔV ₃ and # 1 stand speed reference V ₀ . Therefore, in FIG. 16, in addition to the speed reference V ₀ , ΔV ₁ , ΔV ₂ , ΔV ₃ as control commands, speed reference response time constants T _FF0 , control command response time constants T _FF1 , T _FF2 , T _FF3 As an input. In the case of the configuration as shown in FIG. 16, the FF-ASR command is expressed by the following equation (12), and the primary delay response can be changed by each control command.

Further, by performing FF-ASR current correction 905 using V _FFref , the actual speed V _fb can be set as the FF-ASR command V _FFref . In this case, when the gain of the FF-ASR current correction 905 is changed, the response to all of the speed reference and the control command changes. Therefore, in order to change the control response for each of the control commands ΔV ₁ , ΔV ₂ , ΔV ₃ , The primary delay time constants T _FF1 , T _FF2 , and T _FF3 for the control command are changed.

  FIG. 17 is a diagram showing an inter-stand tension control system for a 4-stand tandem rolling mill according to the present embodiment. As shown in FIG. 17, in the inter-stand tension control system according to the present embodiment, # 1 to # 4 stand speed control devices 611 to 614 are used instead of # 1 to # 4 stand speed control devices 811 to 814. It is done. Further, instead of the tension control between the stands 831 to 833, the tension control between the stands 631 to 633 is used. The # 1 to # 4 stand speed control devices 611 to 614 correspond to the speed control system described in FIG.

FIG. 18 is a diagram showing details of tension control 631 to 633 between the stands. As shown in FIG. 18, each of the inter-stand tension controls 631 to 633 according to the present embodiment uses the control outputs as speed change amounts ΔV _R12ATR , ΔV _R23ATR , ΔV _R34ATR as the respective inputs described in FIG. The response settings T _12ATRFF , T _23ATRFF , and T 34ATRFF for the speed control devices 611 to ₆₁₄ are output. In other words, each inter-stand tension control 631 to 633 functions as a roll speed control unit and an oscillation control unit.

Then, as shown in FIG. 17, the speed change amounts ΔV _R12ATR , ΔV _R23ATR , ΔV _R34ATR and the response settings T _12ATRFF , T _23ATRFF , T _34ATRFF are the rolls arranged immediately before the position where the actual tension is detected, that is, This is input not only to the roll speed control device corresponding to the measurement position of the actual tension, but also to the roll speed control device arranged upstream thereof. For example, the actual tension between the # 3 stand mill 803 and the # 4 stand mill 804 is not only for the control of the # 3 stand mill, which should reflect the actual tension on the roll speed, but also on the upstream side. Are also used for controlling the # 2 stand rolling mill 802 and the # 1 stand rolling mill 801 arranged in the No. 1 stand. This suppresses the oscillation of the actual tension by adjusting the speed control of the immediately preceding roll, and further adjusts the speed control of the upstream roll to adjust another roll based on the speed control of the immediately preceding roll. The influence that occurs in the meantime can be canceled.

  FIG. 19 is a flowchart showing the operation of the speed response adjusting device 660 shown in FIG. As shown in FIG. 19, the speed response adjustment device 660 performs FFT (frequency analysis) of the actual tension at regular intervals (for example, every 1 second) (S1901), and controls the speed control system and the inter-stand tension control system. Based on the set value, the frequency component intensities in the resonance frequency region (for example, ± 5% centered on the resonance frequency) calculated in advance are summed (S1902), and the threshold value (for example, the tension set value 10%) (S1903 / YES), it is considered that resonance of the speed control system has occurred, and the control response is changed by ± ΔT (S1904). That is, in S1902 and S1903, the speed response adjustment device 660 functions as an oscillation detection unit, and in S1904, the speed response adjustment device 660 functions as an oscillation control unit.

This ΔT is ΔT _12ATRFF , ΔT _23ATRFF , ΔT _R34ATRFF shown in FIG. 17, and is used not only for the speed control of the upstream stand between the stands where the oscillation of the tension is detected, but also for the speed control of the upstream stand. Applied. Thereby, even when the speed control between the stands is adjusted by the oscillation of tension between any one of the stands, it is possible to cancel in advance the effect on the tension between the other stands. .

  As ΔT to be changed, a value such as 1 [rad / s] is set in advance. When the tension control between the stands resonates and the actual tension changes, the vibration is suppressed by changing the control response. However, when the tension disturbance of the resonance frequency component occurs, the vibration is reduced only to some extent. For this reason, the control response may be changed indefinitely without being less than the threshold value. Therefore, an upper / lower limit value is set for the control response, and a change exceeding the upper / lower limit value is not performed. This upper limit is, for example, a lower limit of 0.5 times a standard set value determined from equipment specifications, an upper limit of 2.0 times, and the like.

  Such an operation is repeated until the rolling of one material to be rolled is completed (S1905 / NO), and when the rolling of one material to be rolled is completed (S1905 / YES), a standard control response can be determined in advance. Initialized to a value (S1906).

  When changing the control response, whether + ΔT or -ΔT is set to + ΔT from the viewpoint of not lowering the control response, but since there is an upper and lower limit value of the control response, once it has been raised to the upper limit side, A method of lowering to the lower limit side as the − side and increasing to the upper limit side as the + side again is also conceivable.

20 (a), 20 (b), 21 (a), and 21 (b) show an outline of the operation of the speed response adjusting device. Fig.20 (a) is a figure which shows the change of the rolling speed of rolling operation. FIG. 20B is a diagram illustrating an example of the actual tension in a range indicated by a dashed ellipse in FIG. In FIG. 20B, a case where tension oscillation as shown in the figure occurs is considered. In this case, FIG. 21A is a diagram showing a result of performing the FFT using the actual tension for 2 seconds at the timing t ₁ in FIG. 20B. Thus, oscillation can be easily detected by using FFT.

As shown in FIG. 21A, if the FFT result exceeds the threshold value in the resonance frequency region, the control response is changed. Here, a case where the control response is changed by -ΔT (0.05) is taken as an example. Figure 21 (b) is a diagram showing an FFT result at the time of the timing _{t 2} in FIG. 20 (b). The control response by sampling every second continuously lowered, as shown in FIG. 21 (b), when the timing t FFT result at _two time points is below a threshold value at the resonant frequency domain, at which time Stop changing the control response. Oscillation can be suitably suppressed by such processing. When the rolling is completed, the control response is initialized to a preset standard value to prepare for the rolling of the next material to be rolled.

  By doing the above, when performing inter-stand tension control with the stand stand speed as the operating end, the inter-stand tension results are monitored to detect oscillation near the resonance frequency of the speed control system, and the speed control system The oscillation can be suppressed by changing the response. Oscillation can be prevented by detecting the oscillation phenomenon of the control system at an early stage, without deteriorating the operation efficiency such as lowering the rolling speed, and without sacrificing the response of tension control between stands. Improvement and product quality improvement can be achieved.

  Note that the control configuration of the tension control between stands as shown in FIG. 18 is realized by a combination of software and hardware. Here, hardware for realizing each function of tension control between stands according to this embodiment as shown in FIG. 18 will be described with reference to FIG. FIG. 22 is a block diagram showing a hardware configuration of tension control between stands according to the present embodiment. As shown in FIG. 2, the information processing apparatus according to the present embodiment has the same configuration as an information processing terminal such as a general server or a PC (Personal Computer).

  That is, the information processing apparatus according to the present embodiment includes a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102, a ROM (Read Only Memory) 103, an HDD (Hard Disk Drive) 104, and an I / F 105. Connected through. Further, an LCD (Liquid Crystal Display) 106 and an operation unit 107 are connected to the I / F 105.

  The CPU 101 is a calculation unit and controls the operation of the entire information processing apparatus. The RAM 102 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 101 processes information. The ROM 103 is a read-only nonvolatile storage medium and stores a program such as firmware.

  The HDD 104 is a nonvolatile storage medium that can read and write information, and stores an OS (Operating System), various control programs, application programs, and the like. The I / F 105 connects and controls the bus 108 and various hardware and networks. The I / F 105 is also used as an interface for each device to exchange information or input information to the rolling mill.

  The LCD 106 is a visual user interface for an operator to check the state of the information processing apparatus. The operation unit 107 is a user interface such as a keyboard and a mouse for an operator to input information to the information processing apparatus. In such a hardware configuration, a program stored in a recording medium such as the ROM 103, the HDD 104, or an optical disk (not shown) is read into the RAM 102, and the CPU 101 performs calculations according to the program, thereby configuring a software control unit. . The function of the control configuration of the tension control between the stands according to the present embodiment is realized by a combination of the software control unit configured as described above and hardware.

Other embodiments.
In the above embodiment, the oscillation of the tension control between the stands is detected by FFT (frequency analysis). However, from other means, for example, the correlation with the sine wave of the resonance frequency or the phase relationship between the speed command and the actual speed. It is also possible to change the control response of the speed control system by detecting oscillation.

  In the above embodiment, the oscillation of the tension control between the stands is detected from the actual tension and the control response is changed to suppress the oscillation of the tension control between the stands. However, the response of the speed control system is regularly constant. Even if the change is made regularly or randomly within the range, the oscillation can be suppressed when the tension control between the stands oscillates.

  Moreover, in the said embodiment, although the tension control between stands of the hot tandem rolling mill of 4 stands was demonstrated, it is the same as that of the hot tandem rolling mill of arbitrary number of stands and the cold tandem rolling mill of arbitrary numbers of stands. The method is applicable. In the above-described embodiment, the tension control between the stands using the speed as the operation end has been described. However, the same method can be applied to any control using the speed as the operation end, for example, a plate thickness control.

  For example, in the case of plate thickness control, the exit side plate thickness of each stand is used as a state quantity to be measured so as to control the roll speed of the # 3 stand rolling mill 803 based on the exit side plate thickness of the # 3 stand rolling mill 803. The roll speed of the stand is controlled based on the measured outlet thickness. That is, the exit side of each stand is a measurement position, and the roll whose exit side plate pressure is measured is a roll corresponding to the measurement position. And the state quantity control based on the exit side plate thickness of # 3 stand rolling mill 803 is not only for # 3 stand rolling mill 803 but also for # 2 stand rolling mill 802 and # 1 stand rolling mill 801 arranged on the upstream side thereof. Also used for.

  Moreover, in the said embodiment, although the hot tandem rolling mill which uses speed as an operating end was demonstrated, the same method is applicable also in the control system which uses the speed of arbitrary plants as an operating end. That is, as in the case of the tandem rolling mill described above, it is a plant control that repeats the same type of control, and a change in the control amount of a certain control point affects the control of the control point in the preceding stage. For example, the same effect can be obtained by applying the control according to the embodiment. Moreover, in the said embodiment, although demonstrated by adjusting a speed response with a speed control apparatus, adjustment of a speed response is the same also when implemented by the computer side which implements tension control or plate thickness control. The method is applicable.

DESCRIPTION OF SYMBOLS 1 i-1 stunt rolling machine 2 i stand rolling mill 7 Looper 8 Rolled material 9 Tension system 10 Intertension tension control 11 i-1 Stand speed control device 12 i Stand speed control device 13 Hydraulic cylinder 14 Looper branch 15 Looper arm 16 Looper roll 17 Cylinder position detector 20 Looper position control device 30 Rolled material tip 31 Speed-Tension response 32 Plate tension-Cylinder pressure 33 Plate path length change-Tension 34 Looper position-Stand tension 35 Looper machine system 101 CPU
102 RAM
103 ROM
104 HDD
105 I / F
106 LCD
107 Operation Unit 108 Bus 611 # 1 Stand Speed Controller 612 # 2 Stand Speed Controller 613 # 3 Stand Speed Controller 614 # 4 Stand Speed Controller 631 Intertension Tension Control 632 Interstand Tension Control 633 Interstand Tension Control 660 Speed Response adjustment device

Claims (5)

A rolling control device for controlling a tandem rolling mill that rolls a material to be rolled with a plurality of pairs of rolls,
A roll speed control unit for controlling the rotation speed of the roll according to the measurement position and the roll arranged upstream or downstream based on the deviation of the measured state quantity;
An oscillation detection unit that detects oscillation of a state quantity to be measured;
The control response in the control of the rotational speed of the same roll as the control of the rotational speed based on the deviation of the state quantity among the roll corresponding to the measurement position where the oscillation is detected and the roll arranged upstream or downstream thereof. A rolling control device comprising:   The rolling control device according to claim 1, wherein the oscillation detection unit detects the oscillation of the state quantity based on a frequency analysis result of the actual state quantity to be measured. The oscillation detection unit repeatedly detects the oscillation of the state quantity at predetermined intervals,
The oscillation control unit continues to gradually change the control response while the oscillation is detected, and stops changing the control response when the oscillation is no longer detected. The rolling control apparatus described. A plant control device that controls a plant that repeats the same type of processing in a plurality of control targets,
A state control unit that changes the control state of the control object according to the measurement position and the control object on the upstream side or the downstream side based on the deviation of the state quantity to be measured;
An oscillation detection unit that detects oscillation of a state quantity to be measured;
An oscillation control unit that changes a control response in a change in the control state of the control target that is the same as the change in the control state based on the deviation of the state quantity among the control target in which oscillation is detected and the control target upstream or downstream A plant control device comprising: A rolling control method for controlling a tandem rolling mill that rolls a material to be rolled with a plurality of pairs of rolls,
Based on the deviation of the state quantity to be measured, the rotational speed of the roll corresponding to the measurement position and the roll arranged upstream or downstream thereof is controlled,
Detects the oscillation of the measured state quantity,
The control response in the control of the rotational speed of the same roll as the control of the rotational speed based on the deviation of the state quantity among the roll corresponding to the measurement position where the oscillation is detected and the roll arranged upstream or downstream thereof. The rolling control method characterized by changing.

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