JP5838534B2 - Manufacturing method of hot-rolled steel strip - Google Patents

Description

  The present invention relates to a method for producing a hot-rolled steel strip, and in particular, in a hot rolling facility having a configuration in which a pinch roll is provided on the finish mill exit side and the steel strip is cooled by a quenching device provided between the mill and the pinch roll. The present invention relates to a method for manufacturing a hot-rolled steel strip that is suitable for stabilizing the rolling by suppressing fluctuations in tension generated in the steel strip and obtaining a steel strip of good quality.

  The following are known as conventional techniques for suppressing tension fluctuations for similar equipment. In Patent Document 1, which is the first prior art, in order to stabilize cooling, a tension is quickly applied between the pinch roll on the exit side of the finishing mill and the finishing mill to increase the flatness of the plate. A method of cooling is shown.

  Patent Document 2 as a second prior art shows a method of estimating the tension of a steel strip from the current of a motor driving a pinch roll, and controlling the speed of the pinch roll based on the deviation between the estimated tension and the target tension. Has been.

JP 2001-246414 A JP 2003-136108 A

  However, these conventional techniques have the following problems. In the technique of Patent Document 1, there is no disclosure of a technique for suppressing the tension fluctuation of the steel sheet generated before and after cooling or during the cooling, and there is a problem that the threading board becomes unstable due to the tension fluctuation or the quality of the steel sheet is deteriorated. there were.

  Further, the technique of Patent Document 2 has a problem that the accuracy of tension control depends on the accuracy of tension estimated from the motor current of the pinch roll. In general, the steel sheet on the finish mill exit side is thin, and is not a large value as the force acting on the pinch roll. Since the tension fluctuation is estimated from the fluctuation of the motor current corresponding to this force, the tension value may not be estimated properly, and there is a possibility that the tension control cannot be performed properly.

  Therefore, the problem to be solved by the present invention is to stabilize the rolling by properly controlling the tension between the finishing mill and the pinch roll in the hot rolling equipment having a pinch roll on the exit side of the finishing mill. It is to obtain a steel strip of a high quality.

  In order to solve this problem, in the present application, a tension detecting looper is provided between the finishing mill and the pinch roll on the exit side of the finishing mill, and a conventional speed control method during standby and ASR ( In addition to the method of switching the speed control method called Automatic Speed Regulator, a current control method that keeps the pinch roll motor current constant, a speed control method that minimizes the deviation between the detected tension and the target tension, It has a speed control method that minimizes the effect on the tension, detects the state of the steel strip passing through, and switches each control method to be optimal for suppressing the tension fluctuation of the steel strip to control the motor of the pinch roll. It was set as the structure which performs.

  The pinch roll on the exit side of the hot rolling mill has a desired steel strip tension on the entry side of the pinch roll at the timing when the tip of the steel strip is engaged with the pinch roll from the state where the speed is controlled by the waiting speed command. Switch to a method that controls the motor current so that the tension can be detected by the looper, and switch to tension control that minimizes the deviation between the detected tension and the target tension, and the tip of the steel strip is wound around the downcoiler. Switch to a speed control method that minimizes the effect of pinch rolls on the steel strip tension, and switch to a speed control method that uses the steel strip moving speed as a command immediately before the tail end of the steel strip exits the hot rolling mill. .

  As a result, the tension fluctuation of the steel strip can be minimized between the hot rolling mill and the pinch roll, and the rolling can be stabilized and the steel strip quality can be improved.

The figure which shows the structure of the hot rolling control apparatus 100 and its control object 150. FIG. The figure which shows the process of the setup means 110. FIG. The figure which shows the structure of the setup table 111. FIG. The figure which shows the structure of the work roll motor control means 113. The figure which shows the structure of the 1st pinch roll motor control means. The figure which shows the process of the control system switching means 560. FIG. The figure which shows the structure of the looper height control means 115. FIG. The figure which shows the process of the looper position command switching means 710. The figure which shows the structure of the 2nd pinch roll motor control means. The figure which shows the process of the control system switching means 940. The figure which shows the structure of the downcoiler motor control means 117. The figure which shows the process of the control system switching means 1140. The figure which shows the process of the rapid cooling apparatus control means 121 immediately after. The figure which shows the process of the cooling device control means. The figure which shows the process of the 1st pinch roll motor control means. The figure which shows the example of the tension simulation of the steel strip 170.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows the configuration of a hot rolling control device 100 and its controlled object 150 realized in the present invention. The hot rolling control device 100 receives various signals from the control target 150 and outputs control signals to the control target 150.

  First, the configuration of the control target 150 will be described. The control object 150 in the present embodiment includes a hot rolling mill 151 and a rapid cooling device 153 provided immediately downstream thereof, a weir roll 154, a first pinch roll 155, a cooling device 158, a second pinch roll 159, and a downcoiler 160. It is comprised including.

  In FIG. 1, the hot rolling mill 151 is a single rolling facility, but normally has a configuration of a tandem rolling mill in which a plurality of such rolling mills are arranged. In this case, the hot rolling mill 151 is the final rolling mill of the tandem rolling equipment. The hot rolling mill 151 includes a work roll 152 that directly rolls the steel strip 170 and a motor 180 that drives the work roll 152.

  In FIG. 1, the steel plate moves from left to right in the figure. The steel strip 170 having a thickness of about 1 mm to 10 mm finally rolled by the hot rolling mill 151 is immediately cooled by the rapid cooling device 153.

  The weir roll 154 is driven by a motor 181 and functions to prevent the cooling water of the quenching device 153 from flowing downstream.

  The first pinch roll 155 is driven by a motor 182 and applies tension 170 to the steel strip between the hot rolling mill 151 and controls the tension value to coincide with the target value.

  The looper 156 includes a tension detector 157 that supports the steel strip 170 to absorb a variation in tension between the hot rolling mill 151 and the first pinch roll 155 and detect the tension. The driving method of the looper 156 was once an electric method, but in recent years, a hydraulic method has become mainstream.

  The cooling device 158 is a facility for cooling so that the temperature when the steel strip 170 is wound around the downcoiler 160 becomes a target value, and is provided in a normal hot rolling facility.

  The second pinch roll 159 is provided close to the entry side of the downcoiler 160 and functions to enhance the winding property and winding property of the steel strip 170 in the downcoiler 160. Second pinch roll 159 is driven by motor 183.

  The downcoiler 160 is driven by a motor 184 and winds the steel strip 170 into a coil.

  Note that the control target 150 is actually composed of many other devices, but in the present embodiment, description will be limited to the devices constituting the present invention.

  Next, the configuration of the hot rolling control device 100 will be described. The hot rolling control apparatus 100 includes an input unit 101 that captures the state of each device, the position of the leading end of the steel strip 170, and the like from the control target 150, and a control unit that calculates a control command for each device to operate the control target 150. 103, and an output unit 102 that actually outputs the output of the control unit 103 to the control target 150.

  The control means 103 receives information necessary for rolling, such as a steel type, a target plate thickness, and a target plate width, from the host computer 50 for each steel strip 170 to be rolled. Furthermore, the status information of the control object 150 is fetched from the input means 101. In addition, a control command for each device necessary for operating the control target 150 is calculated from these pieces of information.

  Further, the control means 103 refers to the contents of the setup table 111 from the steel type, target plate thickness, target plate width, etc., and calculates the control command for each device of the control target 150, and the speed command received from the setup means 110. The work roll motor control means 113 for controlling the rotation speed of the work roll 152 according to the above, the first pinch roll motor control means 114 for controlling the rotation speed and motor current of the first pinch roll 155, and the rotation of the second pinch roll 159 The second pinch roll motor control means 116 for controlling the speed and motor current, the down coiler motor control means 117 for controlling the rotational speed and motor current of the downcoiler 160, the opening and closing of the cooling valve of the rapid cooling device 153 and the flow rate of the cooling water are controlled. Immediately after the cooling, the cooling device control means 121 and the cooling device 158 are cooled. And a cooling device control unit 122 for controlling the opening and closing of the valve.

  The hot rolling control apparatus 100 is actually configured to include many other control means, but in the present embodiment, the description will be limited to the control means constituting the present invention.

  Hereinafter, the operation of each unit will be described in detail. FIG. 2 shows processing executed by the setup unit 101. The setup means 101 receives information necessary for rolling, such as the steel type of the steel strip to be rolled, the target plate thickness, and the target plate width, from the host computer 50, and then controls the steel strip prior to rolling the steel strip. Calculate the command.

  In the process of the setup means 110 shown in FIG. 2, first, table data is fetched from the setup table 111 in process step S11. The setup table 111 is configured as shown in FIG.

  In the setup table 111 shown in FIG. 3, the steel type, target plate thickness, and target plate width of the steel strip 170 are stored in association with each other. Furthermore, the moving speed of the steel strip 170 with respect to the target plate width (steel strip speed: the speed at which the steel strip 170 is fed out and then proceeds to the downcoiler 160), the height of the looper 156, hot rolling The tension command 1 which is the target value of the tension of the steel strip 170 between the mill 151 and the first pinch roll 155, and the tension command 2 which is the target value of the tension of the steel strip 170 between the first pinch roll 155 and the downcoiler 160 are Stored.

For example, when the steel plate 170 having a steel grade of SS400 is to be rolled to a target plate thickness of 2.0 to 3, 0 (mm) and a target plate width of 1000 to 1400 (mm), this table is a steel strip. The speed should be controlled to 650 (mpm), the height of the looper 156 to 15 (deg), the tension command 1 to 1.5 (kg / mm ² ), and the tension command 2 to 1.5 (kg / mm ² ). Means. The tension command 1 and the tension command 2 are normally set to the same value for the purpose of making the tension value the same on the entry side and the exit side of the first pinch roll.

  In general, the set-up means 110 is omitted from FIG. 1 in addition to the rolling position, rolling load and rotational speed of the work roll 152 of the hot rolling mill, information for identifying the open nozzle of the cooling device, the standby position and pressing force of the pinch roll. However, it is necessary to determine many control commands such as how to move ancillary equipment such as side guides and output them to the controlled object. In this embodiment, the description is limited to the commands related to the present invention, and the setup table 111 is also configured to store only the commands related to the present invention.

  With reference to the setup table 111, a command signal for the control means of each unit is obtained from these numerical values selected according to the conditions. First of all, the steel strip speed will be examined.

  First, when the outer peripheral speed of the roll is divided by π × (roll diameter), it is the rotational speed of the roll. Since both are simply associated with each other, the speed command and the actual speed in the present invention are the rotational speed of the roll. The peripheral speed shall be indicated.

  In accordance with such premise, here, the steel strip obtained by referring to the setup table 111 as a speed command to the first pinch roll motor control means 114, the second pinch roll motor control means 116, and the down coiler motor control means 117 of FIG. The speed is output as it is.

On the other hand, since the speed command of the work roll 152 is different from the steel strip speed, the speed command to be output to the work roll motor control means 113 is calculated in processing step S12. Velocity _{V W} of the work rolls 152 can be calculated by equation (1). However, V _S is a steel sheet speed obtained from the setup table 111, f is the forward slip.

  The advance rate is a value obtained by subtracting 1 from a value obtained by dividing the steel strip speed on the exit side of the work roll 152 by the outer peripheral speed of the work roll 152 when the work roll 152 rotates. The calculation of the advanced rate is described in detail in Chapter 2 (two-dimensional rolling theory) of “Theory and Practice of Sheet Rolling (Japan Steel Association)”. The advance rate can be calculated by a function such as entry side plate thickness, exit side plate thickness, roll diameter, entry side tension, exit side tension, deformation resistance of the steel strip of the hot rolling mill 151.

  In the processing step S13 of FIG. 2, the value extracted from the setup table 111 and the calculated value are output to the corresponding control means 113 to 122 for the corresponding steel strip.

FIG. 4 shows the processing of the work roll motor control means 113. Here, based on the speed command V _{W-ref of} the work roll 152 calculated according to the equation (1) and the difference ΔV _W between the speed results V _W-act of the work roll 152 taken in from the input means 101, the automatic speed adjuster. (Hereinafter referred to as ASR (Automatic Speed Regulator)) 401 calculates a current command C _W-ref output to the motor 180. The automatic speed adjuster 401 calculates the current command C _W-ref by, for example, proportional-integral control shown in Equation (2). In Equation (2), _Gw is a proportional gain, _Tw is an integration time, and S is a Laplace operator.

Actually, the actual current value of the motor 180 is taken in as a minor loop, and closed-loop control (automatic current regulator ACR: Automatic Current Regulator) is performed between the current command C _W-ref. It is omitted because it is not directly related.

  FIG. 5 shows processing of the first pinch roll motor control means 114. The first pinch roll motor control means 114 includes five control means of a first control means 501 to a fifth control means 505, and the tail edge of the steel belt 170 before the first pinch roll is bitten. At each timing during a break, select one of them and execute. The switching of the first control unit 501 to the fifth control unit 505 is processed by the control method switching unit 560. First, the processing of each control unit will be described, and then the processing of the control method switching unit 560 will be described.

The first control unit 501 includes a lead addition unit 510 and an ASR 511. The lead adding means 510 adds a constant speed to the speed command V _p1-ref received from the setup means 110, and outputs a new speed command V _p1-ref + ΔV _lp1 . Here, the speed command V _p1-ref is a value corresponding to the steel strip speed Vs received from the set-up means 110. By adding ΔV _lp1 to this speed command, the first pinch roll 155 rotates at a peripheral speed somewhat faster than the steel strip speed Vs.

The ASR 511 outputs to the motor 182 based on the difference ΔV _p1 between the speed command V _p1 -ref + ΔV _lp1 obtained by the lead adding means 510 and the speed record V _p1 -act of the first pinch roll 155 taken from the input means 101. The current command C _p1-ref to be calculated is calculated. The ASR 511 calculates the current command C _p1-ref by, for example, proportional-integral control shown in Equation (3). G _p1-1 is a proportional gain, and T _p1-1 is an integration time.

The second control unit 502 includes a current value conversion unit 521. The current value conversion means 521 calculates the current command C _p1-ref by, for example, the equation (4). However, A is a constant. T _{1 -ref} is a tension command value of the steel strip 170 between the hot rolling mill 151 and the first pinch roll 155, and the tension command value 1 obtained from the setup table 111 corresponds to this. C ₁ is the current required to rotate the first pinch roll 155, and C ₂ is the total mechanical loss.

Equation (4) is obtained by multiplying the tension command value T _1-ref between the hot rolling mill 151 and the first pinch roll 155 by a constant A to obtain a current necessary for securing the tension, and further, the first pinch roll 155. And C _p1-ref is calculated by adding the current C ₁ required to rotate the entire system including the motor 182 and the mechanical loss C _{2 of the} mechanical system.

  The third control means 503 is provided with ATR1 (531), ATR2 (532), and ASR533 as ATR (Automatic Tension Regulator) for controlling the tension.

Among them, ATR1 (531) is a tension command T _1-ref between the hot rolling mill 151 and the first pinch roll 155 received from the set-up means 110, and a detected value T from the tension detector 157 provided in the looper 156. For the deviation ΔT _{1 from 1-act} , the correction amount V _p1-mod of the speed command of the first pinch roll is calculated so as to reduce ΔT ₁ by, for example, proportional integral control of equation (5). G _p1-2 is a proportional gain, and T _p1-2 is an integration time.

Next, regarding ASR 533, a value obtained by adding the tension command V _p1-ref to the correction amount V _p1-mod obtained in ATR1 (531) is set as a new speed command. The ASR 533 reduces ΔT ₁ by, for example, proportional integral control of the equation (6) based on the new speed command and the difference ΔV _p1 between the speed results V _p1 -act of the first pinch roll 155 fetched from the input unit 101. Thus, the first current command C _p1-ref1 of the first pinch roll is calculated. G _p1-3 is a proportional gain, and T _p1-3 is an integration time.

Further, ATR2 (532) calculates the second current command C _p1-ref2 of the first pinch roll so as to decrease ΔT ₁ by, for example, proportional integral control of equation (7). G _p1-4 is a proportional gain, and T _p1-4 is an integration time.

The current command C _{p1-ref that} is actually output from the third control means to the motor 182 that drives the first pinch roll 155 is C _p1-ref1 obtained by the equation (6) and C obtained by the equation (7). _p1-ref2 is added and calculated by the equation (8).

  In short, the third control means 503 corrects the speed command of the first pinch roll 155 by using ATR1 (531) to correct the deviation between the actual tension and the target tension between the hot rolling mill 151 and the first pinch roll 155. Decrease. On the other hand, for the purpose of relaxing the closed loop delay of ASR 533, a value corresponding to the deviation between the actual tension and the target tension is directly added to the current command by ATR2 (532). As a result of such two-degree-of-freedom tension control, high-response and high-precision tension control becomes possible.

The fourth control unit 504 includes an ASR 541 and a droop control unit 542. The droop control means 542 calculates the droop amount D ₁ corresponding to the output level of the ASR 541 according to the equation (9). Here, ds is a droop coefficient (constant).

In the present embodiment has been sought droop amount is multiplied by a constant to the current command, and a method of calculating the D ₁ as a nonlinear relationship corresponding to the current command, the calculation of the appropriate amount of droop There are various ways.

The fourth control means 504 calculates a new speed command V _p1-ref2 by subtracting the droop amount D1 from the speed command V _p1-ref received from the setup means 110. Then, based on the difference ΔV _p1 between the new speed command V _{p1 -ref2} and the speed record V _{p1 -act} of the first pinch roll 155 fetched from the input means 101, the current command C Calculate _p1-ref . G _p1-5 is a proportional gain, and T _p1-5 is an integration time.

In this control, when the current command C _p1-ref becomes a large value, the speed command becomes a small value correspondingly. That is, since a large value of the current command C _p1-ref is autonomously suppressed, the speed of the first pinch roll 155 in harmony with the steel strip speed is set after the action on the tension of the steel strip 170 is set to a small value. Can be driven by.

The fifth control unit 505 includes an ASR 551. The ASR 551 calculates a current command C _p1-ref to be output to the motor 182 based on the difference ΔV _p1 between the speed command V _p1-ref and the speed record V _p1-act of the first pinch roll 155 taken from the input unit 101. . The ASR 551 calculates the current command C _p1-ref by, for example, proportional-integral control shown in Equation (11). G _p1-6 is a proportional gain, and T _p1-6 is an integration time.

In the case of the first pinch roll motor control means 114, as in the work roll motor control means 113, the actual current value of the motor 182 is actually taken in as a minor loop, and the closed loop between the current command C _p1-ref is obtained. Although control (ACR) is performed, it is omitted because it is not directly related to the present invention.

  FIG. 6 shows the processing of the control method switching means 560. The control method switching means 560 is activated during the standby of the first pinch roll 155 before the steel strip 170 is bitten by the first pinch roll 155. For example, it is activated at the timing when the tip of the steel strip 170 is bitten into the hot rolling mill 151. Alternatively, it is activated for the next steel strip 170 at the timing when the tail end of the steel strip 170 passes through the first pinch roll.

Then, signals related to the steel strip 170 and the control object 150 are fetched from the input means 101, the first control means 501 to the fifth control means 505 are switched by calculation according to the fetched result, and the output of which control means is a current command Decide whether to adopt C _p1-ref . When the fifth control means 505 is finally selected, the process is terminated.

  The control method switching unit 560 first selects the first control unit 501 in processing step S21. The first control means 501 is a process in which the first pinch roll 155 is on standby, and rotates at a speed obtained by adding a lead to the speed of the steel strip 170.

Next, whether or not the pinch roll 155 bites the steel strip 170 is detected based on whether or not P _p1-act, which is the pressing force of the first pinch roll 155, exceeds a certain value in processing step S22. If it is not bitten, the determination process of processing step S22 is continued. If it is determined that it is bitten, the second control means 502 is selected in process step S23.

In process step S24, the tension detector 157 takes in the tension T _1-act of the steel strip 171 between the hot rolling mill 151 and the first pinch roll 155, and the tension detector 157 can detect the tension T _1-act. It is determined whether or not. When it is not detectable, the determination process of process step S24 is continued, and when it is determined that it can be detected, the third control means 503 is selected at process step S25.

As shown in FIG. 5, the third control unit 503 performs control so that the actual tension T _1-act fetched from the input unit 101 matches the tension command T _1-ref received from the setup unit 110.

Further, in processing step S26, it is determined whether or not the difference between the actual tension T _2-act between the pinch roll 155 and the downcoiler 160 and the T _2-ref which is the tension command received from the setup means 110 is equal to or smaller than a predetermined value. T _2-act can be estimated as a value taken in from the input means 101 and corresponding to the current magnitude of the motor 184 that drives the downcoiler.

If the difference is not less than or equal to a certain value, the determination process of processing step S26 is continued. If the difference between T _{2- ref} and T _2-act is determined to be less than or equal to a certain value, the fourth control is performed in process step S27. A means 504 is selected. The difference between the tension result T _2-act and the tension command T _2-ref is equal to or less than a predetermined value. The steel strip 170 is wound around the down coiler 160 and pulled by the down coiler 160 with sufficient force, and the first pinch roll 155 and the down coiler 160 are pulled. The desired tension is established between.

  After this state is confirmed, the fourth control means 504 selects the speed control that does not act on the steel strip tension between the hot rolling mill 151 and the downcoiler 160 in the first pinch roll 155.

In process step S28, it is determined whether the remaining length S _{res-wr-len of} the steel strip length rolled by the hot rolling mill 151 is equal to or less than a predetermined value. If it is not less than a certain value, the determination process of processing step S28 is continued. If it is determined that the value is less than the certain value, it is determined that the tail end of the steel strip 170 is close to the timing of exiting the hot rolling mill 151, and the process step. In step S29, the fifth control unit 505 is selected.

  The fifth control means 505 performs speed control on the first pinch roll 155, and after the tail end of the steel strip 170 has passed through the hot rolling mill 151, the steel is moved between the first pinch roll 155 and the downcoiler 160. A predetermined tension is established in the band 170. Thereafter, when the steel strip 170 has passed through the first pinch roll 155, the processing of the fifth control means 505 is terminated. The steel strip 170 is wound around the downcoiler 160, and the rolling is on standby.

  FIG. 7 shows the processing of the looper height control means 115. The looper height control means 115 shown in FIG. 1 includes a looper position command switching means 701, an APR (Automatic Position Regulator) 702, and an ASR 703. In this embodiment, the case where the looper 156 is hydraulically driven is taken as an example, and the output of the looper height control means 115 is a hydraulic pressure command. If the looper 156 is electrically driven, a current command is used instead of a hydraulic pressure command.

Looper position command switching means 701, and a standby position as the position command of the looper, by selecting the looper height command P _ref sent from the setup unit 110, switches. FIG. 8 shows the processing of the looper position command switching means 701 when one steel strip 170 is rolled.

In the processing step S31 in the initial state of FIG. 8, the looper position is selected as the standby position. The steel strip 170 is bitten by the first pinch roll 155, the payout length S _top-p1-pos is taken from the input means 101, and it is determined whether or not S _top-p1-pos is equal to or greater than a certain value in the processing step S32. To do. If not more than a predetermined value continues to determination processing of the processing step S32, when it is determined that more than a predetermined value, selects a P _ref looper as the height command in the processing step S33.

In process step S34, it is determined whether or not S _res-wr-len which is the remaining length of the steel strip 170 rolled by the hot rolling mill 151 is equal to or less than a predetermined value. If it is not less than the predetermined value, the determination process of process step S34 is continued, and the looper height position command becomes _Pref . If it is determined that the value is equal to or less than a certain value, the tail end of the steel strip 170 is close, so it is necessary to lower the looper height in processing step S35, and the standby position is selected as the height command.

In an APR (Automatic Position Regulator) 702, the speed command V of the looper 156 is based on the difference ΔP between the looper position command P _ref1 output from the looper position command switching means 701 and the looper position command actual value P _act fetched from the input means 101. Calculate _l-ref . The APR 702 calculates the speed command V _1-ref by proportional integral control shown in, for example, the equation (12). G _l-1 is a proportional gain, and T _l-1 is an integration time.

Next, the ASR 703 calculates the hydraulic pressure command O _l-ref of the looper 156 based on the difference ΔV _l between the looper speed command V _l-ref output from the APR 702 and the actual looper speed value V _l-act fetched from the input means 101. To do. The ASR 703 calculates the hydraulic pressure command O _1-ref by, for example, proportional-integral control shown in Equation (13). G _l−2 is a proportional gain, and T _l−2 is an integration time.

  FIG. 9 shows the processing of the second pinch roll motor control means 116 shown in FIG. The second pinch roll motor control means 116 includes three control means of a first control means 901 to a third control means 903, one of which is selected by the control method switching means 940. First, the processing of each control means will be described, and then the processing of the control method switching means 940 will be shown. A function similar to that of the first pinch roll motor control means 114 will be briefly described.

The first control unit 901 includes a lead addition unit 910 and an ASR 911. The lead addition means 910 adds a constant speed to the speed command V _p2-ref received from the setup means 110, and outputs a new speed command V _p2-ref + ΔV _lp2 .

In the ASR 911, based on the speed command V _p2-ref + ΔV _lp2 and the difference ΔV _p2 between the speed results V _p2-act of the second pinch roll 159 fetched from the input means 101, the current command C _p2-ref output to the motor 183 Is calculated. The ASR 911 calculates the current command C _p2-ref by, for example, proportional-integral control shown in Equation (14). G _p2-1 is a proportional gain, and T _p2-1 is an integration time.

The second control unit 902 includes an ASR 921 and a droop control unit 922. Loop control means 922 according to (15), calculates the amount of droop _{D 2} corresponding to the magnitude of the output of ASR921. Ds is a droop coefficient (constant).

In the present embodiment has been sought droop amount is multiplied by a simple constant to the current command, may be calculated D ₁ as a nonlinear relationship corresponding to the current command.

In the second control means 902, and droop D ₁ by subtracting from the speed command V _p1-ref received from the setup unit 110, calculates a new speed command V _p1-ref2. Then, based on the difference ΔV _p2 between the new speed command V _{p1 -ref2} and the speed record V _p2 -act of the second pinch roll 159 taken from the input means 101, the ASR 921 performs proportional integral control shown in the equation (16), Command C _p2-ref is calculated. G _p2-2 is a proportional gain, and T _p2-2 is an integration time.

In the control of the second control means 902, as in the droop control applied to the first pinch roll 155, a large value of the current command C _p2-ref is autonomously suppressed. And the second pinch roll 159 can be driven at a speed in harmony with the steel strip speed.

The third control unit 903 includes an ASR 931. The ASR 931 calculates the current command C _p2-ref to be output to the motor 183 based on the speed command V _p2-ref and the difference ΔV _p2 between the speed results V _p2-act of the second pinch roll 159 fetched from the input unit 101. To do. The ASR 931 calculates the current command C _p2-ref by, for example, proportional-integral control shown in Equation (17). G _p2-3 is a proportional gain, and T _p2-3 is an integration time.

  FIG. 10 shows the processing of the control method switching means 940. The control method switching means 940 is activated during the standby of the second pinch roll 159 before the steel strip 170 is bitten by the second pinch roll 159. For example, it is activated at the timing when the tip of the steel strip 170 is bitten by the first pinch roll 155. Alternatively, at the timing when the tail end of the steel strip 170 passes through the second pinch roll 159, it is activated for the next steel strip 170.

And the signal related to the steel strip 170 or the control object 150 is taken in from the input means 101, the first control means 901 to the third control means 903 are switched by calculation according to the fetched result, and the output of which control means is the current command Decide whether to adopt C _p1-ref . When the third control means 505 is finally selected, the process is terminated.

  The control method switching means 940 first selects the first control means 901 in processing step S41. The first control means 901 is a process in which the second pinch roll 159 is on standby, and rotates at a speed obtained by adding a lead to the speed of the steel strip 170.

  Next, in processing step S42, it is determined whether or not the steel strip 170 is wound around the downcoiler 160 and the downcoiler 160 is loaded on. The load-on of the downcoiler 160 is usually determined based on the operation of various rolls of the downcoiler 160 and the current performance of the motor 184 being a certain value or more. If the load is not turned on, the determination process in step S42 is continued. If it is determined that the load is turned on, the second control means 902 is selected in process step S43.

  The fact that the downcoiler 160 is load-on indicates that the steel strip 170 is wound around the downcoiler 160 and is pulled by the downcoiler 160 with sufficient force.

  After this state is confirmed, the second control means 902 selects the control that minimizes the action applied to the steel strip tension between the hot rolling mill 151 and the downcoiler 160 in the second pinch roll 159.

In processing step S44, it is determined whether the remaining length S _{res-p1-len of the} steel strip sandwiched between the first pinch rolls 155 is equal to or _smaller than a certain value. If it is not less than a certain value, the determination process of the processing step S44 is continued. In S45, the third control means 903 is selected.

  In the third control means, speed control is performed on the second pinch roll 155, and a tension is established in the steel strip 170 between the second pinch roll 159 and the downcoiler 160. Thereafter, the steel strip 170 passes through the second pinch roll 159, and the second pinch roll 159 is on standby.

  FIG. 11 shows the configuration of the downcoiler motor control means 117 shown in FIG. The downcoiler motor control means 117 includes three control means of a first control means 1101 to a third control means 1103, one of which is selected by the control method switching means 1140. First, the processing of each control unit will be described, and then the processing of the control method switching unit 1140 will be shown.

  In this embodiment, the speed of the downcoiler 160 is the outer peripheral speed of the downcoiler 160. Since the outer diameter of the downcoiler 160 changes due to the winding of the steel strip 170, the rotational speed of the motor 184 changes due to the influence of the downcoiler 160. In other words, when the outer shape of the downcoiler 160 increases, the rotational speed of the motor 184 decreases due to the influence.

The first control unit 1101 includes a lead addition unit 1110 and an ASR 1111. The lead addition means 1110 adds a constant speed to the speed command V _d-ref received from the setup means 110, and outputs a new speed command V _d-ref + ΔV _ld .

The ASR 1111 calculates a current command C _d-ref to be output to the motor 184 based on the speed command V _d-ref + ΔV _ld and the difference ΔV _d between the speed results V _d-act of the downcoiler 160 fetched from the input unit 101. . The ASR 1111 calculates the current command C _d-ref by, for example, proportional-integral control shown in Equation (18). G _d-1 is a proportional gain, and T _d-1 is an integration time.

Second control means 1102, to the tension instruction _{T 2} of the strip 170 between the first pinch rolls 155 and Daunkoira 160 (or hot rolling mill 151 and Daunkoira 160), current Daunkoira 160 commensurate with _{T 2} A current value calculating means 1121 for calculating a value, an inertia calculating means 1122 for calculating an inertia of the downcoiler 160 from a weight of a coil wound around the downcoiler 160, and a current value calculating means 1123 for calculating a current value balanced with the calculated inertia. I have.

First, the current value calculation unit 1121 calculates a current value C _{dt1 -ref that} is balanced with the tension command value T _{2 -ref} set by the setup unit 110 according to, for example, equation (19). W is a plate width, t is a plate thickness, D is a coil diameter, Gr is a gear ratio, and Kt is a torque-current conversion coefficient.

  Here, the coil diameter D can be calculated from the plate thickness of the steel strip 170 taken from the input means 101 and the length of the steel strip 170 taken up by the downcoiler 160. The length of the steel strip 170 wound around the downcoiler 160 is obtained by integrating the speed of the steel strip 170 after the steel strip 170 is wound around the downcoiler 160.

That is, the coil diameter D can be obtained by solving the equations (20) and (21). However, in these formulas, _{D 0} is the inner cylinder diameter of Daunkoira 160 (mandrel diameter), t is the plate thickness, N is the number of turns of the steel strip 170 wound Daunkoira 160, Vs the plate speed, t0 is the steel strip The time when 170 is wound around the downcoiler 160 and t ₁ means the current time.

  The inertia calculating means 1122 calculates the inertia Jd of the downcoiler 160 around which the steel strip 170 is wound, for example, by the equation (22). Note that ρ is the specific gravity of the steel strip 170.

The current value calculation means 1123 calculates the acceleration / deceleration torque from the total inertia obtained by adding the inertia JM of the downcoiler 160 itself to the inertia Jd calculated by the equation (22), and converts this into a current command C _dt2-ref and outputs it. . A is the degree of acceleration or deceleration of the downcoiler 160, and Kt is the torque-current conversion coefficient.

The second control unit 1102 adds C _{dt1 -ref} and C _{dt2 -ref} , and outputs a value obtained by adding the loss current as necessary as a current command C _d -ref to the downcoiler 160.

  The third control unit 1103 includes a stop processing unit 1131 and an ASR 1132 that control a stop position of rotation of the downcoiler 160. The stop processing means 1131 performs the determination process of the formula (24) for completing the winding of the tail end of the steel strip 170 wound around the downcoiler 160 at a predetermined position.

That is, when the remaining length S _{res-d-len of} the steel strip 170 is equal to or greater than a predetermined value S _{res-d-len-ltd,} the speed command V _d-ref received from the set-up means 110 is output as the speed command of the steel strip 170. To do.

When the remaining length of the steel strip 170 is equal to or less than S _{res-d-len-ltd} , position control is performed to complete the winding of the tail end of the steel strip 170 at a predetermined position. However, in this determination, (V _d−ref−s ) max = V _d−ref , G _d−2 is a proportional gain, and θ ₀ is a stop angle of the tail end of the steel strip 170.

Then, V _d-ref-s is output as a speed command for the downcoiler 160.

The ASR 1132 calculates the current command C _d-ref from the V _d-ref-s and the actual speed of the down-coiler 160 received from the input unit 101 by, for example, proportional-integral control shown in the equation (25). G _d-3 is a proportional gain, and T _d-3 is an integration time.

  FIG. 12 shows the processing of the control method switching means 1140. The control system switching means 1140 is activated during the standby of the downcoiler 160 before the end of the steel strip 170 is bitten by the downcoiler 160. For example, it is activated at the timing when the tip of the steel strip 170 is bitten by the first pinch roll 155. Alternatively, it is activated for the next steel strip 170 at the timing when the tail end of the steel strip 170 passes through the downcoiler 160.

Then, signals related to the steel strip 170 and the controlled object 150 are fetched from the input means 101, and the first control means 1101 to the third control means 1103 are switched by calculation according to the fetched result and adopted as the current command C _d-ref. The control means to be determined is determined. When the third control unit 1103 is finally selected, the process is terminated.

The control method switching unit 1140 first selects the first control unit 1101 in processing step S51. The first control means 1101 is a process in which the downcoiler 160 is on standby, and the speed (V _{d− ) obtained} by adding the lead ΔV _d to the speed command value V _d−ref corresponding to the speed command of the steel strip 170. _ref + ΔV _d ).

Next, after the steel strip 170 is wound around the downcoiler 160 and the downcoiler 160 is loaded on in the processing step S52, the target value T2 _-ref and the actual value T2 _-act of the tension between the first pinch roll 155 and the downcoiler 160 are set. Determine whether the difference is below a certain value. The actual value of the tension can be estimated from the current of the motor 184 that drives the downcoiler 160 using the equations (19) to (23).

  When the difference between the target value and the actual value of the tension between the first pinch roll 155 and the downcoiler 160 is not less than a certain value, the determination process of the processing step S52 is continued, and when it is determined that the difference is less than the certain value. In the processing step S53, the second control unit 1102 is selected, and the control for maintaining the tension between the first pinch roll 155 and the downcoiler 160 at the target value is selected.

In processing step S54, it is determined whether or not the remaining length S _{res-p2-len of the} steel strip sandwiched between the second pinch rolls 159 is equal to or less than a predetermined value. If it is not less than the predetermined value, the determination process of S12-4 is continued. When it is determined that the value is equal to or less than the predetermined value, it is determined that the tail end of the steel strip 170 is close to the timing when it passes through the second pinch roll 159, and the third control unit 1203 is selected in processing step S55.

  The third control means performs speed control for stopping the downcoiler 160 in a state where the tail end of the steel strip 170 wound around the downcoiler 160 is stopped at a predetermined position. Thereafter, the downcoiler 160 stops and rolling is on standby.

  FIG. 13 shows the processing of the immediate quenching device control means 121. Immediately after the steel strip 170 is rolled by the hot rolling mill 151, the rapid cooling device control means 121 outputs a control command to the cooling device 153 immediately after cooling the steel strip 170.

While the hot rolling mill 151 finishes rolling the steel strip 170 and waits for the next steel strip 170 to be rolled, the cooling device 153 immediately stops cooling. In process step S61, the looper 156 determines whether or not the tension T _1-act between the hot rolling mill 151 and the first pinch roll can be detected. That is, whether the hot rolling mill 151 has started rolling the next steel strip 170, the first pinch roll 155 has bitten the tip of the steel strip 170, and the looper 156 has risen to start detecting the tension T ₁ -act. Determine.

T _1-act continues the judgment until detectable, when enabled detected T _1-act, and outputs a cooling start command immediately after the cooling device 153 in the process step S62. In process step S63, the remaining length S _res-w-len of the steel strip 170 rolled by the hot rolling mill 151 is taken from the input means 101, and it is determined whether or not S _res-w-len has become a certain value or less. If S _res-w-len is not below a certain value, cooling is continued. Moreover, the determination process of process step S63 is repeated. When S _res-w-len becomes a certain value or less, the cooling is stopped in the processing step S64. Normally, S _res-w-len is set in accordance with the timing when the control position of the looper 156 is lowered, and the cooling is stopped before the tension T _1-act cannot be detected.

  In the present embodiment, the cooling device 153 is provided with a steel strip on the condition that the tension between the hot rolling mill 151 and the first pinch roll 155 can be detected and the tension can be controlled by the first pinch roll using the detected value. Although the case of cooling 170 has been described as an example, the control method of the first pinch roll 155 to the downcoiler 160 realized in the present invention can be applied regardless of the cooling specification of the cooling device 153 immediately after.

  For example, the same can be applied to the case where the quenching apparatus 153 immediately starts cooling from the front end of the steel strip 170 and continues cooling to the tail end. Further, as the control of the immediately after cooling device 153, not only the start and end of the cooling shown in the embodiment, but also finely controlling the opening / closing and flow rate of each nozzle provided in the immediately following cooling device 153 as the operation end. Conceivable. It is also conceivable to obtain uniform cooling characteristics in the longitudinal direction of the steel strip 170 by changing the opening and closing of each nozzle and the flow rate in association with the speed and detected temperature of the steel strip 170 and changing the steel strip 170 as it moves.

  FIG. 14 shows the processing of the cooling device control means 122. The cooling device control means 122 outputs a control command to the cooling device 158 that cools the steel strip 170. While the hot rolling mill 151 finishes rolling the steel strip 170 and waits for the steel strip 170 to be rolled next, the cooling device 158 stops cooling.

  In processing step S71, the distance between the tip position of the steel strip 170 and the cooling device 158 is calculated from the value of the tip position of the steel strip 170 taken from the input means 101, and it is determined whether or not this is below a certain value. That is, it is determined whether the steel strip 170 has approached the cooling device 158.

  If it is not determined that the tip of the steel strip 170 has approached the cooling device, the determination process of process step S71 is repeated. If it is determined that the vehicle is approaching, a cooling command is output to the cooling device 158 in processing step S72.

  In process step S73, it is determined whether the tail end of the steel strip 170 has passed a predetermined position near the outlet of the cooling device 158. If not, cooling continues. Moreover, the determination process of process step S73 is continued. When the tail end of the steel strip 170 passes a predetermined position in the vicinity of the outlet of the cooling device 158, the process proceeds to process step S74, and cooling is stopped.

  In this embodiment, the cooling start timing and end timing of the cooling device 158 have been described in accordance with standard specifications. However, for the reasons of winding around the downcoiler 160 and the quality of the steel strip 170, the tip and tail of the steel strip 170 are used. A specification that does not cool the edges is also conceivable. Even in this case, the determination value of the distance between the tip position of the steel strip 170 and the cooling device 158 at the processing step S71 and the predetermined vicinity of the outlet of the cooling device 158 through which the tail end of the steel strip 170 passes at the processing step S73. By appropriately setting the position of the present invention, the present invention can be similarly applied.

  Further, as the control of the cooling device 158, it is conceivable to finely control not only the start and end of the cooling shown in the embodiment but also the opening and closing of each nozzle provided in the cooling device 158 and the flow rate thereof as operation ends. . It is also conceivable to obtain uniform cooling characteristics in the longitudinal direction of the steel strip 170 by changing the opening and closing of each nozzle and the flow rate in association with the speed and detected temperature of the steel strip 170 and changing the steel strip 170 as it moves.

  FIG. 15 shows a flow in which the first pinch roll 155 processes one steel strip 170. The first step shown in the processing step S81 is a step before the first pinch roll 155 bites the steel strip 170. As shown by the first control means 501, the first pinch roll 155 The speed is controlled at the peripheral speed obtained by adding the lead speed to the moving speed.

  When the first pinch roll 155 bites the tip of the steel strip 170, the entry side tension of the first pinch roll 155 (the tension between the hot rolling mill 151 and the first pinch roll 155) is set to the target value in processing step S82. Therefore, the process transitions to a second step of controlling the current value of the motor 182 so that the first side pinch roll 155 has a desired entry side tension as a current command. That is, the control shown in the second control means 502 is performed.

  When the looper 156 rises and the tension detector 157 can detect the tension of the steel strip 170, the process transitions to the third step shown in the process step S83, and the first pinch roll 155 uses the detected tension to It is controlled by tension control in which the tension between the rolling mill 151 and the first pinch roll 155 is a target value. That is, the control shown in the third control means 503 is performed.

  When the steel strip 170 is bitten in the downcoiler 160 and tension is established between the hot rolling mill 151 and the downcoiler 160, the droop function shown by the fourth control means 504 in the processing step S84 and the first pinch roll 155. The process transitions to a fourth step in which the speed control including the above is performed. That is, the first pinch roll 155 is speed-controlled at a peripheral speed synchronized with the speed of the steel strip 170, and is controlled to minimize the action on the tension of the steel strip 170.

  Immediately before the tail end of the steel strip 170 exits the hot rolling mill 151, the control of the first pinch roll 155 shifts to the fifth step shown in the processing step S85, and the speed command corresponding to the moving speed of the steel strip 170 is set. Therefore, it is operated with speed control. That is, the control shown in the fifth control means 505 is performed. When the tail end of the steel strip 170 passes through the first pinch roll 155, the fifth step is finished.

  Each time the hot rolling mill 151 rolls the steel strip 170, the first pinch roll 155 repeats the process steps S81 to S85 of FIG.

  In FIG. 16, an example of the simulation result regarding the 2nd process and the 3rd process in which the tension | tensile_strength fluctuation | variation of the steel strip 170 becomes a problem is shown. The simulation includes many assumptions including the response of each device, but each explanation is omitted.

  Results The horizontal axis is the elapsed time, the vertical axis is the tension between the hot rolling mill 151 and the first pinch roll 155, and 1601 is the transition of the tension value. Immediately after that, the rapid cooling device 153 starts cooling the steel strip 170 after the tension detector 157 detects the tension of the steel strip 170, and the steel from which the work roll 152 is discharged by the influence of the roll eccentricity of the hot rolling mill 151. The simulation is performed by taking as an example a case where the plate speed of the belt 170 varies by 0.05%.

  1602 is the timing at which the first pinch roll 155 bites the steel strip 170, and no tension is generated in the steel strip 170 in the first step so far. In the second step after the first pinch roll 155 bites the steel strip 170, periodic tension fluctuations due to roll eccentricity are superimposed on the tension value corresponding to the first pinch roll 155 current value. .

  In 1604, the tension detector 157 can detect the tension, and immediately after the cooling of the steel strip 170 by the rapid cooling device 153 starts, the control of the first pinch roll 155 shifts to the third step. Immediately after that, due to the rapid plate shrinkage caused by the cooling of the rapid cooling device 153, a large tension is temporarily generated between the hot rolling mill 151 and the first pinch roll 155, but the processing step of the first pinch roll 155 is detected as a tension detection value. By switching to tension control using, the generated excessive tension is suppressed in about 500 ms.

  Thereafter, periodic fluctuations due to roll eccentricity remain, but fluctuation amplitude is suppressed by tension control. Although the results are omitted, the tension fluctuation of the steel strip 170 becomes a small value in the subsequent fourth and fifth steps. 16 is obtained in the rolling direction of the steel strip 170 by switching the first control means 501 to the fifth control means 505 in the first pinch roll motor control means 114.

  INDUSTRIAL APPLICABILITY The present invention is effective as a method for producing a steel strip produced by a hot rolling facility having a configuration in which a pinch roll is provided on the finish mill exit side and the steel strip is cooled by a quenching device provided between the mill and the pinch roll. Applicable.

100: Control device for hot tandem rolling mill 101: Input means 102: Output means 103: Control means 110: Setup means 111: Setup table 113: Work roll motor control means 114: First pinch roll motor control means 115: Looper height Length control means 116: second pinch roll motor control means 117: downcoiler motor control means 121: immediately after quenching device control means 122: cooling device control means 150: controlled object 151: hot rolling mill 153: immediately after cooling device 154: weir Stop roll 155: Brother 1 pinch roll 156: Looper 157: Tension detector 158: Cooling device 159: Brother 2 pinch roll 160: Downcoiler 170: Steel strip 501: First control means 502: Second control means 503: First Third control means 504: fourth control means 505: fifth Your means

Claims (3)

A hot rolling mill for rolling a steel strip, a pinch roll disposed on the outlet side of the hot rolling mill, a rapid cooling apparatus disposed immediately between the hot rolling mill and the pinch roll, and the pinch roll When manufacturing a hot-rolled steel strip with a control object equipped with a downcoiler disposed on the exit side of the pinch roll and a downcoiler that winds up the treated steel strip and forms a coil A first step of controlling the speed of the pinch roll using a value obtained by adding a predetermined read speed to the moving speed of the steel strip as a speed command;
A second step of controlling the current of a motor that drives the pinch roll so that the steel strip tension on the inlet side of the pinch roll becomes a desired value;
A third step of tension control the pinch rolls as the tension of the steel strip measured at a tension detector provided in the looper has a desired value,
A value corresponding to a current command to the motor that drives the pinch roll is calculated as a speed correction amount, and the speed of the pinch roll is controlled using a value calculated from the moving speed of the steel strip and the speed correction amount as a speed command. And the process of
A fifth step of controlling the speed of the pinch roll using the moving speed of the steel strip as a speed command ,
Start the first step before the pinch roll bites the steel strip,
After the pinch roll bites the steel strip, the process moves to the second step,
After the tension detector provided in the looper can detect the tension of the steel strip, the processing is transferred to the third step,
After the end of the steel strip is wound around the downcoiler, the process is transferred to the fourth step,
Before the tail end of the steel strip exits the hot rolling mill, the processing is transferred to the fifth step,
When the tail end of the steel strip passes through the pinch roll, the fifth step is terminated,
One after another for each strip to be manufactured, the manufacturing method of the hot rolled strip, wherein a call from the first step is subjected to the fifth step. In the manufacturing method of the hot-rolled steel strip according to claim 1 ,
The third step calculates a speed command of the pinch roll according to a tension deviation between the tension of the steel strip measured by a tension detector provided in the looper and a desired value,
A motor current command for driving the pinch roll calculated according to a deviation between the speed command and the actual speed of the pinch roll is a first current command,
A motor current command for driving the pinch roll calculated according to the tension deviation is set as a second current command,
A method for manufacturing a hot-rolled steel strip, comprising: controlling a current of a motor that drives the pinch roll using a value obtained by adding a first current command and a second current command as a current command. In the manufacturing method of the hot-rolled steel strip according to claim 1 or 2 ,
After the process moves to the third step, cooling of the steel strip is started by the quenching apparatus immediately after the rapid cooling apparatus.

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