JP6625500B2 - Rolling mill control device, rolling mill control method, and control program - Google Patents

Description

  The present invention relates to a control device for a rolling mill, a control method for a rolling mill, and a control program, and more specifically, a control device for a rolling mill for suppressing a thickness variation due to a variation in hardness of a material to be rolled, The present invention relates to a control method and a control program for a rolling mill.

  In a rolling mill that is a plant that efficiently produces a thin metal material, a sheet thickness defect due to uneven hardness of a material to be rolled may occur. Hardness unevenness refers to the case where the hardness (deformation resistance) of the material to be rolled is not uniform. If there is unevenness in hardness in the longitudinal direction (rolling direction), the degree of thickness deformation of the material to be rolled is different, so the rolling mill Thickness fluctuation occurs in the outlet thickness.

  Rolling is generally performed by passing the material to be rolled through a rolling mill a plurality of times from the thickness of the original sheet to the thickness of the product. If there is unevenness in hardness, the thickness of the material to be rolled varies due to the difference in hardness. In rolling a plurality of times, a sheet thickness variation newly occurs every time. In order to improve the thickness accuracy of products, thickness control is carried out in rolling mills, but it is difficult to remove thickness fluctuations that occur every time due to uneven hardness by thickness control. .

  The thickness variation due to hardness unevenness generated during a certain rolling is detected by the incoming thickness gauge at the next rolling, and the thickness variation is suppressed by performing the thickness control in a feedforward manner. In addition, a new thickness variation occurs due to hardness unevenness, so that a gain larger than a normal control gain is required. To solve this problem, Patent Literature 1 describes that the presence or absence of hardness unevenness is determined by frequency analysis and the control gain of feedforward thickness control is changed.

  Further, in Patent Document 2, the degree of hardness unevenness in the material to be rolled at the time of this rolling is determined, and when the degree of hardness unevenness is large at the next rolling, the gain of feedforward control may be increased. Has been described.

Patent No. 3384330 Japanese Patent No. 5581964

  In the prior art, in order to remove hardness unevenness (longitudinal deformation resistance change), feed-forward control is performed using the sheet thickness change generated during the previous rolling as the incoming side sheet thickness change during the next rolling, and the hardness unevenness is reduced. The control gain of the feedforward control is changed depending on the presence or absence.

  The feedforward control is a proportional control, and the control effect can be maximized by outputting the phase and the amplitude in accordance with the target control deviation. The thickness control is performed by changing the interval between the work rolls of the rolling mill or the roll speed of the tension reel or the rolling mill based on the thickness deviation of the material to be rolled measured by the thickness gauge. Here, there is a dead time and a time response in detecting the thickness deviation of the thickness gauge, changing the work roll interval and changing the speed. Therefore, there is a limit to the thickness deviation frequency at which a large thickness control effect can be obtained with respect to the thickness deviation disturbance. Therefore, along with the adjustment of the thickness control, the rolling speed is restricted as a measure in operation. Depending on the type of material to be rolled and what kind of processing was performed as an upper step, the cycle of hardness unevenness (length on the material to be rolled) and the size differ, so that the operation technician can change the actual thickness of the exit side plate. While observing the situation, the rolling speed that can secure the required thickness accuracy is determined and the speed is limited.

  The rolling operation is performed such that the rolling mill is accelerated from a stopped state, rolled at a constant speed, then decelerated and stopped. Speed limitation is performed by limiting the rolling speed at a constant speed after the acceleration operation.

  However, the fluctuation period in the longitudinal direction of the material to be rolled is not constant, though it depends on the cause of the unevenness of the hardness which causes the fluctuation of the exit side plate thickness. In addition, since the rolling speed is limited at a constant speed in accordance with the shortest hardness unevenness period, the rolling speed is long even at a place where the rolling speed is long and there is no problem with the thickness accuracy even if the rolling speed is increased. And the operating efficiency is reduced.

  In view of the above, it is an object of the present invention to provide a rolling mill control device, a rolling mill control method, and a control program capable of improving the operation efficiency while maintaining the thickness accuracy.

  From the above, the present invention is a control device of a rolling mill adapted to control a rolling speed of a rolling mill according to a speed set value given by a speed setting device, and is wound around a tension reel of the rolling mill. A coil diameter calculation unit for calculating the outer diameter of the coil as the material to be rolled, a fluctuation period calculation unit for calculating the fluctuation period of the hardness unevenness of the material to be rolled from the coil diameter, and the fluctuation period is predetermined by a control response of the thickness control. Equipped with a rolling speed limiting device including a limiting calculation unit for limiting the rolling speed of the rolling mill to be equal to or less than the set value, the rolling speed limiting device limits the rolling speed of the rolling mill according to the actual coil diameter during rolling. It is characterized by the following.

Further, the present invention includes two tension reels and a rolling mill, and after rolling the rolled material unwound from the coil, which is the rolled material wound on one tension reel, by using a rolling mill, A method for controlling a cold rolling mill that winds up a tension reel,
The fluctuation cycle of the hardness unevenness of the material to be rolled out from the one tension reel is predicted from the outer diameter of the coil being rolled around the one of the tension reels,
The rolling speed of the rolling mill is controlled such that the fluctuation cycle of the hardness unevenness is equal to or less than a preset value determined by a control response of the thickness control of the rolling mill.

  Also, the present invention provides a program storage memory in a computer system including an input unit, an output unit, a program storage memory, a data storage memory, an operation unit, and a bus connecting these components. A control program for controlling a rolling mill, wherein the rolling mill controls the rolling speed of the rolling mill according to a speed set value given from an output unit of the computer system, Is a coil diameter calculation program for obtaining the outer diameter of the coil, which is the material to be rolled, wound on the tension reel of the rolling mill using the data obtained from the input unit, and the hardness unevenness of the material to be rolled from the coil diameter. The rolling cycle of the rolling mill is controlled so that the changing cycle is equal to or less than a predetermined value according to the control response of the thickness control. And a limit calculation program, rolling speed of the rolling mill obtained by limiting operation program is characterized in that given rolling mill through the output unit.

  By applying the present invention, the rolling speed is automatically changed so that the thickness control becomes a frequency at which the thickness deviation of the exit side can be suppressed in accordance with the occurrence cycle of the hardness unevenness causing the exit side thickness variation. Therefore, it is possible to improve the operation efficiency while maintaining the thickness accuracy.

The figure which shows the example of a control structure of a single stand rolling mill. The figure which shows the outline of the entrance side board thickness control apparatus 20. The figure which shows the outline | summary of the delivery side thickness control device 18. The figure which shows the mode of the rolling performed between upper and lower work rolls. The figure which shows the outline of the roll gap operation method in the rolling mill 1. The figure which shows the example of operation | movement operation of a rolling mill. FIG. 4 is a diagram for explaining temperature unevenness during batch annealing as a factor of causing hardness unevenness of the material to be rolled 30. The figure which shows the time change of rolling speed and delivery side sheet thickness deviation. The figure which shows the concept of a speed limit. The figure which shows the specific structural example of the rolling speed limitation apparatus 220. The figure which shows what the amplitude becomes as a result, giving the control output which multiplied the control gain to the sine wave as a control deviation and assumed it. FIG. 7 is a diagram illustrating an amplitude X of a control output y when a control gain G and a phase shift Δ are changed. FIG. 1 is a diagram showing an apparatus configuration when the present invention is realized by a computer system.

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

  As an embodiment of the present invention, a case where the present invention is applied to a single stand rolling mill including one rolling mill, an entrance tension reel, and an exit tension reel as shown in FIG. 1 will be described.

  FIG. 1 shows a control configuration of a single stand rolling mill. The single-stand rolling mill has an entrance-side tension reel 2 on the entrance side and an exit-side tension reel 3 on the exit side with respect to the rolling direction of the rolling mill 1 (from left to right in the case of this drawing). The rolling is performed by rolling the rolled material 30 unwound from the side tension reel 2 by the rolling mill 1 and then winding it up by the discharge side tension reel 3. The rolling mill 1 includes an upper work roll 121A, a lower work roll 121B, an upper intermediate roll 122A, a lower intermediate roll 122B, an upper backup roll 123A, and a lower backup roll 123B from the rolled material 30 side with the rolled material 30 interposed therebetween. The roll gap control device 7 for controlling the thickness of the material 30 to be rolled and the mill speed for controlling the speed of the rolling mill 1 by changing the roll gap between the upper and lower work rolls. The control device 4 is installed. The entry-side tension reel 2 and the exit-side tension reel 3 are driven by an electric motor, and an entrance-side tension reel control device 5 and an exit-side tension reel control device 6 are installed as devices for driving the electric motor and the electric motor. You.

  At the time of rolling, a speed command is output from the rolling speed setting device 10 to the mill speed control device 4, and the mill speed control device 4 performs control to keep the speed of the rolling mill 1 constant. On the entry side and the exit side of the rolling mill 1, rolling is performed stably and efficiently by applying tension to the material 30 to be rolled. The entrance tension setting device 11 and the exit tension setting device 12 calculate the tension required for that purpose. Based on the input side and output side tension set values calculated by the tension setting devices 11 and 12, the input side tension reel 2 and the output side tension reel 3 are passed through the input side tension reel control device 5 and the output side tension reel control device 6, respectively. A current value for obtaining a motor torque required to apply the set tension to the material to be rolled 30 is obtained by the input-side tension current converter 15 and the output-side tension current converter 16, and the input-side tension reel controller 5 And the output side tension reel control device 6. The entry-side tension reel control device 5 and the exit-side tension reel control device 6 control the motor current so as to be a given current, and the motor torque applied to the entry-side tension reel 2 and the exit-side tension reel 3 from the motor current. This gives a predetermined tension to the material to be rolled.

  The tension current converters 15 and 16 calculate a current set value (a motor torque set value) to be a tension set value based on a control model of the tension reel. Using the actual tensions measured by the entrance-side tension meter 8 and the exit-side tension meter 9 installed on the side and the exit side, the tension setting value is corrected by the entrance-side tension controller 13 and the exit-side tension controller 14. Then, the current value supplied to the tension current converters 15 and 16 and set in the entrance tension reel controller 5 and the exit tension reel controller 6 is changed.

  Further, since the thickness of the material to be rolled is important in terms of product quality, the thickness is controlled. The output side thickness control device 18 controls the roll gap of the rolling mill 1 using the roll gap control device 7 based on the actual thickness detected by the output side thickness gauge 17. Is controlled by In addition, the sheet thickness on the entry side of the rolling mill 1 is controlled by the entry side sheet thickness control device 20 from the actual sheet thickness detected by the entry side sheet thickness gauge 19 so that the exit side sheet thickness of the rolling mill 1 becomes constant. The gap is controlled by operating using the roll gap control device 7. In FIG. 1, reference numeral 210 denotes an incoming deflor, 211 denotes an outgoing deflor, and 220 denotes a rolling speed limiting device added according to the present invention. The operation of the rolling speed limiting device 220 will be described later.

  In a single-stand rolling mill as shown in FIG. 1, when the material to be rolled 30 has unevenness in hardness in its longitudinal direction, a control method for minimizing a thickness variation caused by unevenness in hardness is studied. .

  The rolling is performed by deforming the material 30 to be rolled between the upper and lower work rolls 121A and 121B, as shown in FIG. At this time, the material to be rolled 30 is pulled by the entrance tension Tb and the exit tension Tf, and is deformed by the rolling load P determined by the gap (roll gap) S between the upper and lower work rolls 121A and 121B. The entrance side plate thickness H becomes the exit side plate thickness h. At the same time, due to the rolling phenomenon, the incoming plate speed becomes slower than the work roll speed, and the outgoing plate speed becomes faster. As shown in FIG. 3, the relationship between the work roll speed VR and the entrance speed Ve and the exit speed Vo can be expressed by using the advanced rate f and the reverse rate b.

  In a single stand rolling mill, reverse rolling is performed. In FIG. 1, rolling is performed by winding the material to be rolled out from the entrance tension reel 2 on the exit tension reel 3 (rightward in the rolling direction) according to the rolling direction. When the material to be rolled on the entrance-side tension reel 2 is wound on the output-side tension reel 3, the material to be rolled is unwound from the exit-side tension reel 3 and then wound on the entrance-side tension reel 2 so that the material is rolled from right to left. Rolling operation (to the left in the rolling direction) is performed.

FIG. 2A shows an outline of the entrance side thickness control device 20, and FIG. In the feedforward thickness control device 204, the entry thickness deviation ΔH measured by a thickness gauge on the entry side of the rolling mill (19 in the right direction in the rolling direction, 17 in the left direction in the rolling direction) is calculated by the following method. Then, the feed processing is performed to a position immediately below the feed gap 1, feedforward control is performed by multiplying the input side sheet thickness deviation, the conversion gain of the roll gap, and the control gain _GFF , and the control output is output to the roll gap control device 7 of the rolling mill 1. 201 is a time compensation determined by a transfer time T _{EX-MILL of the} material 30 to be rolled just below the entry-side thickness gauge 19 and the mill 1 and a difference time T _FF between the control output timing shift amount ΔT _FF for the entry-side thickness control. This is a transfer time compensating unit to be performed. 202, conversion gain providing the ratio of the plastic constants Q and mill modulus M, is a control gain that gives a gain G _FF.

(1) is an equation defining the compensation time _{T FF} in transport time compensation unit 201.

In the feedback thickness control device 205, the exit thickness difference Δh measured by the thickness gauge on the exit side of the rolling mill (19 in the left direction in the rolling direction and 17 in the right direction in the rolling direction) is added to the exit thickness difference Δh. The feedback control is performed by multiplying the deviation to the conversion gain from the roll gap and the control gain _GFB , and output to the roll gap control device 7 of the rolling mill 1. Incidentally, 181, conversion gain that gives the ratio determined by plastic constants Q and mill modulus M, 182 control gain to provide a gain _{G FB,} is 183 is integral element.

  The entry-side thickness control device 20 has a feed-forward control device 204 and a feedback control device 205, and in the case of a right-hand rolling direction, connects a signal from the entry-side thickness gauge 19 to the right-hand side 51 of the rolling direction in FIG. 2A. , Feeds to the feed forward control device 204 to function as feed forward control. In the case of the left direction in the rolling direction, the signal from the entry thickness gauge 19 is connected to the left direction 52 in the rolling direction of FIG. Inputting into the device 205 functions as feedback control.

  Similarly, the outlet-side sheet thickness control device 18 has a feed-forward controller 204 and a feedback controller 205, and in the case of the left-hand direction in the rolling direction, sends the signal from the outlet-side thickness gauge 17 to the left-hand side 54 in the rolling direction in FIG. 2B. By connecting and inputting to the feedforward control device 204, it functions as feedforward control. In the case of the right direction in the rolling direction, the signal from the exit thickness gauge 17 is connected to the right direction 53 in the rolling direction in FIG. Inputting into the device 205 functions as feedback control.

  Generally, the feedforward control device 204 is implemented by proportional control, and the feedback control device 205 is implemented by integral control.

  Thus, in the case of the right-hand direction in the rolling direction, the roll gap control device 7 receives, as a control command value, a signal determined by the sum of the integral output from the output-side thickness control device 18 and the proportional output from the input-side thickness control device 20. In the case of application in the left-hand direction in the rolling direction, a signal determined by the sum of the proportional output from the exit-side thickness control device 18 and the integral output from the entrance-side thickness control device 20 is applied as a control command value.

  The roll gap control device 7 performs control such that the actual roll gap matches the control command value received from the entrance-side thickness control device 20 and the exit-side thickness control device 18. The variation in the exit side thickness of the rolling mill 1 cannot be detected immediately below the rolling mill 1 at the position where the variation occurs, and is detected by the exit side thickness gauge 17 installed at a position distant from the rolling mill 1. There is a dead time until detection. Therefore, the feedback control is usually an integral control. Therefore, it is difficult to remove the high-frequency component of the exit side plate thickness variation.

  For this reason, the feedforward control device 204 performs feedforward control so that fluctuations in the inlet-side sheet thickness, which is one of the causes of the fluctuations in the outlet-side sheet thickness, do not cause fluctuations in the outlet-side sheet thickness. The feedforward control is a proportional control, and the control effect can be maximized by outputting the phase and the amplitude in accordance with the target control deviation.

  Assuming that a sine wave is used as the control deviation, a control output obtained by multiplying the sine wave by a control gain is given, and FIG. 10 shows how the amplitude results. As a control output for the sine wave sin (ωt), a sine wave multiplied by the control gain G and the phase shift Δ is created, and the obtained result is defined as y. In this case, the control output y is expressed as in equation (2). Further, the amplitude of y can be expressed by Expression (3), and the phase can be expressed by Expression (4). In FIG. 10, reference numeral 101 denotes a phase unit, 102 denotes a control gain unit, and 103 denotes a subtraction unit.

  FIG. 11 is a graph showing the amplitude X of the control output y when the control gain G and the phase shift Δ are changed. From FIG. 11, it can be seen that the larger the phase shift Δ, the larger the amplitude, and if the phase shift exceeds 60 degrees, not only the control effect cannot be obtained but also the opposite effect. In addition, it can be seen that by performing the control, when there is a phase shift Δ, the phase of the resulting control result y is shifted from the original sine wave sin (ωt).

  That is, even if the control gain of the feedforward control, which is the proportional control, is increased, when the phase of the control output is shifted from the control target (when the phase shift Δ exists), not only the control effect is reduced but also the control effect is reduced. In some cases, it will make it worse. Therefore, in order to obtain a sufficient control effect, it is necessary to make the phase shift Δ as small as possible. In the present invention, the phase shift Δ at which a sufficient control effect can be obtained will be described as 30 degrees or less. Note that this value changes depending on the target product conditions and the like, and may be changed as appropriate.

  In the right-hand direction in the rolling direction, the entry-side thickness control device 20 performs control using the entry-side thickness deviation detected by the entry-side thickness gauge 19. The entry-side thickness gauge 19 generally measures the thickness by projecting radiation such as X-rays on a material to be rolled and detecting the transmittance of the radiation with a radiation detector. Low-pass filtering is performed to remove noise generated at the time of detection, and there is a response delay. Also, in the thickness gauge, various arithmetic processes are performed by a computer, and there is a dead time.

In addition to the dead time and response delay in the input-side thickness gauge 19 for detecting the thickness deviation, the input-side thickness control device 20 is implemented by a computer, so that the dead time from sampling to calculation to output of the computer, the control operation terminal There is a dead time and a response delay in the roll gap control device 7 which is the following. Therefore, it is necessary to determine the control timing shift amount ΔT _FF for the input side thickness control in consideration of the dead time and the response delay from those detectors to the control operation end, and to minimize the phase shift Δ. .

  The roll gap control device 7 also has a dead time and a time response. FIG. 4 shows an outline of a roll gap operation method in the rolling mill 1. Here, a case where the roll gap is operated by hydraulic pressure will be described as an example.

  The hydraulic cylinder 111 is installed under the lower backup roll 123B of the rolling mill 1, and the hydraulic cylinder 111 is operated to change the position of the piston 118. The rod 117 changes the position of the lower backup roll 123B. The interval (roll gap S) between the work roll 121A and the lower work roll 121B is changed. A fixed pressure is applied to the hydraulic cylinder 111 on the lower backup roll 123B side (rod 117 side, back pressure side), and the hydraulic pressure on the opposite side (downward side) is adjusted by the hydraulic pressure adjusting device 112, so that the pressure applied to the piston 118 is increased. And the position of the piston 118 is changed. The position of the piston 118 in the hydraulic cylinder 111 is detected by a position detector 113.

  In the roll gap control device 7, a position deviation is obtained from the detected piston position 114 and the position command value 115, and a control gain 116 is applied to operate the hydraulic adjustment device 112. This processing is generally performed by computer processing, and there is a dead time. The rolling load required for rolling the material 30 to be rolled is applied to the rod 117 of the hydraulic cylinder 111 in addition to the weight of the lower work roll 121B, the lower intermediate roll 122B, and the lower backup roll 123B. When a pressure exceeding these forces (rolling force) is applied to the rolling down side, the piston 118 rises, and the roll gap becomes small. If the pressure on the lower side of the rolling force is reduced, the piston 118 moves down and the roll gap increases.

  Since the roll gap control of the rolling mill is performed as described above, there is a time response until the piston position 114 matches the position command value 115. Due to the time response, the amplitude of the piston position 114 generally becomes smaller than the amplitude of the position command value 115 as the frequency of the position command value 115 becomes higher, and the control effect of the entry-side plate thickness control 20 decreases.

  As described above, in the case of the right-hand row in the rolling direction, a signal determined by the sum of the integral output from the output-side thickness control device 18 and the proportional output from the input-side thickness control device 20 is applied as a control command value, and the input-side thickness gauge is applied. 19, in the entry side thickness control system composed of the entry side thickness control device 20 and the roll gap control device 7, since there is a dead time and a time response, the control effect differs depending on the fluctuation cycle of the entry side thickness deviation. . Since the time response has the characteristic that the amplitude decreases as the frequency increases, the control effect decreases as the input side thickness disturbance frequency increases. In the following, the fluctuation cycle of the sheet thickness deviation caused by the unevenness in the hardness of the material to be rolled will be treated as the entry side sheet thickness disturbance frequency. The entry-side thickness disturbance frequency is the reciprocal of the variation cycle of the thickness deviation.

  The exit side thickness accuracy of the rolling mill 1 is important for product quality, and is required to be equal to or less than a predetermined fixed value (guaranteed value). For this purpose, assuming that the attenuation of the exit side thickness deviation caused by the variation of the entrance side thickness, the attenuation by the entrance side thickness control is the entrance side thickness deviation attenuation, the entrance side thickness deviation is determined from the entrance side thickness deviation result and the guaranteed value. Can do things. Since the control effect of the inlet side thickness control system changes according to the inlet side thickness disturbance frequency, the inlet side thickness deviation is required to obtain the attenuation of the inlet side thickness deviation necessary for the outlet side thickness deviation to be less than the guaranteed value. The disturbance frequency may be set to be equal to or lower than a frequency fdlimit at which a control effect required for the disturbance is obtained. The entry-side sheet thickness disturbance is a sheet thickness variation occurring on the sheet of the material to be rolled, and thus the period is determined by the length on the sheet. Therefore, the entry side thickness disturbance frequency fluctuates depending on the speed of the material to be rolled. Since the speed of the material to be rolled is determined by the peripheral speed of the work roll 121 of the rolling mill 1, the rolling speed, which is the work roll speed of the rolling mill 1, may be limited.

  Here, in order to make the exit side thickness deviation equal to or less than the guaranteed value for a given material to be rolled, the entrance side thickness deviation attenuation amount that causes the exit side thickness deviation due to the entrance side thickness variation to be 50% or less. Is required. The delay time and the dead time existing in the control system are set as follows. This is an example, and changes depending on the configuration of the rolling mill and the detector. First, it is assumed that the thickness gauge has a filter (first-order lag) characteristic of about 20 ms. It is assumed that the control device has a dead time of 20 ms sampling (calculation cycle), a dead time of about 10 ms in taking in the PIO, and a dead time of about 10 ms in outputting to the control operation terminal. It is also assumed that the control operation end itself has a response of about 20 ms (a phase delay of about 8 Hz and a phase delay of about 90 degrees) (first-order delay). This results in a total waste time of about 80 ms. In order to make this fall within the range of 30 degrees, it is necessary that the thickness variation has a cycle larger than 960 ms. Thus, if the control gain G is 0.75 to 1.0, it is possible to control the outboard thickness deviation caused by the inboard thickness disturbance to 50% or less. When the thickness variation is smaller than 960 ms, the exit thickness variation cannot be reduced to 50% or less. Therefore, in this case, in order to obtain a sufficient control effect capable of keeping the exit side sheet thickness deviation equal to or less than the guaranteed value, it is necessary to set the frequency of the sheet thickness fluctuation as a disturbance to 1 Hz or less.

  As described above, the maximum frequency of the input side thickness deviation required to obtain the attenuation amount of the input side thickness deviation, which is determined from the actual value of the input side thickness deviation and the guaranteed value of the material to be rolled, is controlled by the input side thickness control system. Can be determined from the response.

  FIG. 5 shows an operation example of the rolling mill. On the side of the rolling mill 1, an operation panel 300 for an operator to operate is installed. Switches (operation switches) necessary for the operation are installed on the operation panel 300, and the operation is performed by operating the operation switches.

  At the time of operation, first, the operation mode of the rolling mill is selected by the operation mode selection switch 150. The operation modes include a normal “rolling” operation 152, a “operation stop” 153 for stopping the rolling operation, and a “roll change” 151. The “roll change” 151 is a mode in which each roll is replaced periodically or when the roll surface condition is significantly deteriorated because the work roll, the intermediate roll, the backup roll, and the like are worn by the rolling operation.

  Further, on the operation panel 300, an operation state selection switch 160 for selecting an operation state is provided for each operation mode. For example, when the “rolling” mode for performing the rolling operation is selected, the operation state selection switch 160 includes switches 161, 162, and 163 for “slow motion”, “acceleration”, “hold”, and “stop” as operation states. 164 are provided, and the rolling operation is performed by operating the rolling speed of the rolling mill using these switches. When "slow motion" is selected, the rolling mill 1 accelerates to a predetermined slow motion speed and operates at that speed. By selecting “acceleration”, the rolling speed is accelerated to a predetermined set speed. The operation is continued at the current rolling speed by selecting "hold", the speed is reduced to the slowing speed by selecting "slow motion", the operation is performed at the slow motion speed, and the rolling speed is set to 0 from the slow motion speed by selecting "stop". Stop the rolling mill.

  The unevenness in temperature during batch annealing is one of the causes of unevenness in hardness, which is a cause of thickness disturbance of the material 30 to be rolled. As shown in FIG. 6, the batch annealing is performed as a part of the processing of the material to be rolled. The material 201 to be rolled in a coil shape is put in the cover 202 and heated by the burner 200. When the burner 200 is installed at two locations in the circumferential direction as shown in FIG. 6, the plate temperature of the material 201 to be rolled is higher in the vicinity of the burner than in other portions, so that the temperature difference in the circumferential direction is lower. Occurs, for example, the portion 203 where the plate temperature is high remains as a portion whose hardness is softer than other portions. When this coil 201 is transferred from the batch annealing furnace to the entry side tension reel of a rolling mill and the material to be rolled is unwound, when the material to be rolled is unwound from the coil 201, the interval between the positions of the soft portions of the plate is: The distance changes in accordance with the radial position when the coil has been formed, and the leading end of the unrolled material has a longer interval, and the leading end has a shorter interval toward the rear end. Further, the interval of the fluctuation is の of the circumference when the coil is formed.

  Since the unevenness in hardness appears as a change in the thickness of the sheet, the change in the thickness of the output side sheet in such a case is as shown in FIG. FIG. 7 shows the time change of the rolling speed and the deviation of the exit side plate thickness. When the rolling speed is constant, the leading end portion (right end portion in FIG. 7) unwound from the coil has a longer cycle of thickness variation, and the trailing end portion (left end portion in FIG. 7) has a shorter cycle of thickness variation. Can be seen. In the case of reverse rolling, the direction of the flow of time is reversed in FIG. 7, and the cycle of the plate thickness variation gradually changes from a short state to a long state.

  As described above, in the case of hardness unevenness caused by batch annealing, the thickness variation cycle varies from the leading end to the trailing end of the material to be rolled. Therefore, in order to limit the thickness variation frequency to a constant value, it is necessary to change the rolling speed in accordance with the thickness variation cycle. It is difficult for the rolling mill operator to change the rolling speed by manual operation, and it is difficult to achieve this.Based on past experience, the rolling mill speed is determined according to the shortest part of the sheet thickness fluctuation cycle, and operation is continued at the same speed. Things are being done. In this case, there is no problem in the accuracy of the sheet thickness on the delivery side, but the rolling operation is performed at a constant speed in a portion where the sheet thickness fluctuation period is long, although the rolling speed is increased.

  In order to prevent a decrease in operation efficiency, the rolling speed of the rolling mill 1 may be changed according to the thickness variation cycle. FIG. 8 illustrates the concept of the speed limit. In the case where the plate thickness variation period changes from a long period to a short period as in the example in FIG. 8, the rolling speed may be increased at first, and the rolling speed may be decreased in accordance with the change in the plate thickness variation period. In addition, when the plate thickness fluctuation period fluctuates from a short period to a long period as in the example in the lower part of FIG. 8, the rolling speed may be reduced at first, and the rolling speed may be increased in accordance with the change in the plate thickness fluctuation period. .

  In the following, a case will be described in which the present invention is implemented with respect to a variation in sheet thickness when batch annealing as shown in FIG. 6 is performed. Since the burners 200 are installed at two locations facing each other, it is predicted that a thickness variation will occur at a half cycle of the reel circumference. Further, it is assumed that the coil after the batch annealing is directly inserted into the entrance tension reel 2 of the rolling mill shown in FIG. 1 and the material to be rolled is unwound.

  The present invention is implemented by the rolling speed limiting device 220 in FIG. FIG. 9 shows a specific configuration example of the rolling speed limiting device 220.

The coil diameters of the entrance-side tension reel 2 and the exit-side tension reel 3 can be obtained during the operation of the rolling mill 1 by a method as shown in FIG. Entry side Defuroru 210 and the entry side tension speed _N EDR of the reel _{2, N ETR} can be detected by a rotation speed meter mounted on a respective rotation axis. In Figure 9, shows an example in which the rotational speed N _EDR entry side Defuroru 210 is detected by the entering-side Defuroru speed detector 210S, to obtain a rotational speed N _ETR entry side tension reel 2 from the inlet side tension reel controller 5 I have. Also, the diameter D _{EDR of the} entry side deflor 210 is known because it can be measured mechanically.

Since the entry side tension reel peripheral velocity _{V ETR} and entry side Defuroru peripheral velocity _{V EDR} are the same, the diameter _{D ETR} entry side tension reel, it is possible to determine by equation (5).

In the ingress tension reel diameter calculation unit 222 of FIG. 9, the entering-side Defuroru rotational speed _{N EDR,} from the entry side tension reel rotational speed _{N ETR} and entry side Defuroru diameter _{D EDR,} according to the above equation, the entry side tension reel diameter D Calculate _ETR . In FIG. 9, the method for obtaining the diameter of the entrance tension reel 2 has been described. However, the diameter _DETR of the _output tension reel 3 can be determined using the same method.

Considering the case shown in FIG. 6 which occurs during batch annealing as hardness unevenness, a cycle of hardness unevenness occurs twice in the circumferential direction of the reel of the input-side tension reel 2 into which the coil of the material to be rolled 30 is inserted. Should be. Therefore, the frequency _{f DETR} hardness unevenness, when the peripheral velocity of the entry side tension reel 2 and _{V ETR,} (6) relationship equation is established.

  The variation period calculation unit 223 in FIG. 9 calculates the variation period f by executing the equation (6).

Further, the speed V _MILL of the rolling mill 1 can be expressed by Expression (7) using the reverse speed b.

From the above, the speed limit V _MILLlimit of the rolling mill determined by the equation (8) is assumed.

If limit the speed _{V MILL} mill 1 (8) of the speed limit _{V MILLlimit,} it is possible to limit the frequency of the hardness unevenness _{f Dlimit.} In limiting calculation unit 224, based on equation (8), obtaining the maximum rolling speed _{V Milllimit} corresponding to the entry side tension reel diameter _{D ETR.}

9 limits the rolling speed command, which is the output Vin of the rolling speed setting device 10, so as not to exceed the maximum rolling speed V _MILLlimit obtained by the limiting calculating portion 224, To output the speed command Vout.

  When a reverse rolling mill is assumed as the rolling mill, in FIG. 1, the material 30 to be rolled out is unwound from the entrance tension reel 2 and wound up by the exit tension reel 3, from left to right in FIG. When the rolling (first pass) is completed, the rolled material 30 is unwound from the output tension reel 3 and is wound on the input tension reel 2 from right to left (second pass).

In this case, the coil thickness _DETR of the entry-side tension reel 2 also indicates the thickness variation cycle in the state where the sheet-thickness is inserted into the entry-side tension reel 2. However, the length of the plate on the material to be rolled is increased by the reduction in plate thickness due to rolling. These relationships can be obtained by the constant law of mass flow of equation (9). In the equation (9), H is the thickness of the incoming plate, h is the thickness of the outgoing plate, L is the length of the incoming plate, and l is the length of the outgoing plate.

In the present case, by rolling from left to right, the plate thickness of the material to be rolled, from the rolled material thickness H _0, is changed to 1-pass Medellin delivery thickness h _1. Therefore, the calculation formula of the expression (8) in the limit calculation unit 224 needs to be the expression (10).

  When the rolling in the second pass is completed, the rolling in the third and subsequent passes is also performed by changing the rolling direction according to the specification of the material to be rolled.

If the above relationship due to a plurality of inversions is generalized, the limit operation unit 224 may calculate the speed limit V _MILLlimit by the equation (8) for the first pass and by equation (11) for the second and subsequent passes. . Here, hp _-1 is the exit side plate thickness one pass before.

  By using the method described above, by changing the rolling speed according to the expected cycle of hardness unevenness, while maximizing the control effect of the thickness control system, maximizing the operation efficiency It is possible to increase.

  In the present embodiment, the rolling speed limiting method when the fluctuation cycle of the hardness unevenness in the batch annealing as shown in FIG. 6 changes according to the change in the coil diameter has been described.

  FIG. 12 shows an apparatus configuration when the present invention is realized by a computer system. The computer system 70 in FIG. 12 includes an input unit I, an output unit O, a memory ROM for storing a program, a memory RAM for storing data, a calculation unit C, and a bus Bus connecting these. ing. The computer system 70 may collectively control the overall control device of the rolling mill in FIG. 1, but here, a description will be given focusing on the function of the rolling speed limiting device 220 of the present invention.

The computer system 70 that realizes the function of the rolling speed limiting device 220 includes, as inputs necessary for the calculation, a rolling speed command that is an output Vin of the rolling speed setting device 10, an input-side deflor rotation speed N _EDR , and an input-side tension reel rotation. The speed _NETR is input via the input unit I at an appropriate constant cycle. Further, if necessary, for example, the inlet side deflore diameter D _EDR is obtained. The output unit O outputs a speed command Vout to the mill speed controller 4 as a calculation result. These inputs and outputs and various data as intermediate products are temporarily stored in a memory RAM for data storage.

  The arithmetic unit C sequentially reads out and executes a group of programs for realizing the function of the rolling speed limiting device 220 from the memory ROM for storing the program, and fetches necessary data from the memory RAM for storing data. Also, the internal calculation results are stored and temporarily stored in a memory RAM for data storage together with various numerical values of the intermediate products.

  A program group for realizing the function of the rolling speed limiting device 220 stored in the memory ROM for storing the program includes an entry-side tension reel diameter calculation program Pr1 corresponding to the calculation of the expression (5) and the program of the expression (8). The speed limit setting calculation program Pr2 corresponding to the calculation, the rolling speed limit calculation program Pr3, and the like. Each program of these programs corresponds to the entry-side tension reel diameter calculation unit 222, the limit calculation unit 224, and the speed limit calculation unit 225 shown in FIG. 9, and each time necessary data is stored in a memory for data storage. The rolling speed limit calculation program Pr3 finally outputs the speed command Vout to the mill speed control device 4 via the output unit O from the RAM.

1: Rolling machine 2: Inlet tension reel 3: Outlet tension reel 4: Mill speed controller 5: Inlet tension reel controller 6: Lower tension reel controller 7: Roll gap controller 8: Inlet tensiometer 9: Outlet tension meter 10: Rolling speed setting device 11: Inlet tension setting device 12: Outlet tension setting device 13: Inlet tension control device 14: Outlet tension control device 15: Inlet tension current converter 16: Outlet tension current converter 17: Outlet thickness gauge 18: Outlet thickness control device 19: Inlet thickness gauge 20: Inlet thickness control device 30: Rolled material 121A: Upper work roll 121B: Lower work roll 122A: Upper Intermediate roll 122B: Lower intermediate roll 123A: Upper backup roll 123B: Lower backup roll 204: Feed forward thickness controller 205: Feedback thickness controller 210: inlet side Defuroru 211: exit side Defuroru 222: inlet side tension reel diameter calculation unit 223: variation period calculation unit 224: limit calculating unit 225: speed limit computing unit

Claims (3)

A control device for a rolling mill, which is configured to control a rolling speed of a rolling mill according to a speed setting value given by a speed setting device,
A coil diameter calculation unit that calculates an outer diameter of a coil that is a material to be rolled wound on a tension reel of the rolling mill, a fluctuation period calculation unit that calculates a fluctuation period of hardness unevenness of the material to be rolled from the coil diameter, A rolling speed limiting device including a limit calculating unit that limits a rolling speed of the rolling mill so that a fluctuation cycle is equal to or less than a predetermined value determined by a control response of the thickness control, wherein the rolling speed limiting device is performing rolling. A rolling mill control device, wherein the rolling speed of the rolling mill is limited according to the actual coil diameter. It has two tension reels and a rolling mill, and the rolled material unwound from the coil, which is the rolled material wound on one tension reel, is rolled by a rolling mill and then cooled on the other tension reel. A method for controlling a cold rolling mill,
The fluctuation cycle of the hardness unevenness of the material to be rolled out from the one tension reel is predicted from the outer diameter of the coil being rolled around the one of the tension reels,
A method for controlling a rolling mill, wherein the rolling speed of the rolling mill is controlled such that a fluctuation cycle of the hardness unevenness is equal to or less than a set value predetermined by a control response of a thickness control of the rolling mill. An input unit, an output unit, a memory for storing a program, a memory for storing data, a calculating unit, and a memory for storing the program in a computer system including a bus connecting them. A program for controlling a rolling mill,
The rolling mill is configured to control a rolling speed of the rolling mill according to a speed set value given from an output unit of the computer system,
The program for controlling the rolling mill is a coil diameter calculation program for obtaining an outer diameter of a coil which is a material to be rolled wound on a tension reel of the rolling mill using data obtained from the input unit, and A variation cycle calculation program for determining a variation cycle of the hardness unevenness of the material to be rolled; and a limit calculation for limiting a rolling speed of the rolling mill so that the variation cycle is equal to or less than a set value predetermined by a control response of sheet thickness control. Program and
A rolling mill control program, wherein a rolling speed of the rolling mill obtained by the restriction calculation program is given to the rolling mill via the output unit.

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