JP2003010909A - Method for controlling wall thickness for steel plate rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the wall thickness of a rolled steel plate from fluctuating by an oil film effect by delaying a timing by which a speed AGC is output. SOLUTION: A steel plate 1 is rolled by a rolling mill 2. The volume of change (ΔS) of a rolling gap in accordance with a rolling speed is read out through an interpolation table 5 indicating the relationship between the rolling speed and the fluctuation value of the exit wall thickness, and a cylinder 7 of the rolling mill 2 is controlled based on a gap reference value 6. By this way, the cylinder 7 controls the gap volume of the rolling mill 2 with the rolling speed to control the wall thickness of the steel plate 1. Since the fluctuation of the exit wall thickness is delayed than that of the rolling speed due to the oil film effect, the speed AGC is delayed at the time of speed shifting from deceleration to slow moving. A time to delay the speed AGC is a lag time obtained from the speed fluctuation of the rolling mill 2 corresponding to the thickness fluctuation of the steel plate 1. Further, the speed AGC can be delayed even at the time of accelerating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate thickness control method during cold rolling of a steel plate, and more particularly to a plate thickness control for improving plate thickness fluctuation due to speed fluctuation when cold rolling in a steel plate rolling machine. Regarding the method.

[0002]

2. Description of the Related Art In recent years, a steel plate rolling machine for cold rolling is required to have a high accuracy of uniformity in the thickness of rolled steel plate, and continuous rolling operation is required to improve quality and productivity. Is progressing. For example, in continuous operation, fluctuations in tension that occur during acceleration / deceleration of a steel sheet rolling mill are suppressed and the thickness of rolled steel sheet is managed with high accuracy. Patent 310296
Japanese Unexamined Patent Publication No. 1 (1994) discloses a technique of controlling a load current of a steel sheet rolling machine according to an inertial force of a rolling drive unit to suppress harmful tension fluctuations during acceleration and deceleration and controlling a plate thickness of a rolled steel sheet. Is disclosed. As a result, the yield of the rolled steel sheet is improved, and the cost is reduced by improving the productivity.

[0003]

However, in the conventional plate thickness control method for the steel plate rolling machine, the plate thickness on the output side fluctuates due to the oil film effect (oil film effect) during acceleration / deceleration in the process of rolling the steel plate. There is a risk of doing it.
In other words, when accelerating, the rolling oil that flows into the surface of the steel sheet increases, so the oil film becomes thicker and thinner, and when decelerating, the rolling oil that flows into the surface of the steel sheet decreases, so the oil film becomes thinner. Becomes thicker. Conventionally, in order to suppress such a variation in strip thickness, an operation of varying the output amount (AGC amount) of automatic strip thickness control (AGC) according to the rolling speed is performed.

That is, by compensating the speed effect, the AGC amount corresponding to the rolling speed is output to control the strip thickness. However, fluctuations in the inflow and outflow of rolling oil tend to lag behind fluctuations in the rolling speed. Therefore, when the speed changes from deceleration to gradual motion, which is the lowest constant speed, the fluctuation of rolling oil inflow and outflow is controlled even though the plate thickness is controlled with a constant AGC amount after shifting to gradual motion. Due to the delay, the reduction of rolling oil is continuing, and the oil film becomes thinner. As a result, the plate thickness tends to become extremely thick in the process of shifting from deceleration to gradual traveling.

The present invention has been made in view of such circumstances, and an object thereof is to delay the timing at which the AGC amount is output so that the thickness of the rolled steel sheet varies due to the oil film effect. It is intended to provide a plate thickness control method for a steel plate rolling machine that suppresses the above and can appropriately control the plate thickness of the steel plate.

[0006]

In order to solve the above-mentioned problems, a method of controlling the plate thickness of a steel plate rolling machine according to the present invention is a method of feeding a plate thickness control amount according to a rolling speed by cold rolling to feed back a steel plate. In the plate thickness control method for a steel plate rolling machine that performs rolling, the delay time of feedback of the plate thickness control amount is set according to the delay time of the plate thickness change of the steel plate with respect to the rolling speed. That is, the sheet thickness control amount to be fed back (speed effect compensation: speed AGC) is delayed by the time period during which the oil film effect is delayed with respect to the change in rolling speed. Thereby, even if the fluctuation of the inflow and outflow of the rolling oil lags the fluctuation of the rolling speed, the fluctuation of the plate thickness due to the oil film effect can be suppressed.

Further, the plate thickness control method for a steel sheet rolling mill according to the present invention is, in the above-mentioned invention, a first step of detecting a speed fluctuation of a rolling line of the steel sheet rolling machine and a speed detected by the first step. The second procedure for measuring the variation in the thickness of the steel sheet with respect to the variation, and the third step of obtaining the delay time of the variation in the thickness of the steel sheet with respect to the rolling speed based on the variation in the thickness measured in the second procedure The plate thickness control of the steel plate is performed through a procedure and a fourth procedure of setting a feedback delay time of the plate thickness control amount to the same value as the delay time obtained in the third procedure. . Further, the speed fluctuation amount detected in the first procedure is characterized in that it is a speed fluctuation amount when the speed of the rolling line changes from deceleration to slow motion which is the lowest constant speed.

That is, according to the plate thickness control method for a steel plate rolling mill of the present invention, at the time of speed fluctuation from deceleration to slow motion, the timing at which the speed AGC is output for the delay time obtained from the speed fluctuation corresponding to the thickness variation. Delay.
That is, the variation in the thickness of the rolled steel sheet with respect to the variation in the speed of the rolling line is measured, and the delay time is obtained based on the measured variation in the thickness. Then, the speed AGC is delayed by the calculated delay time between the deceleration and the slow motion. Thereby, even if the fluctuation of the inflow / outflow of the rolling oil is delayed from the fluctuation of the rolling speed, the fluctuation of the plate thickness due to the oil film effect can be suppressed.

Further, in the plate thickness control method for a steel plate rolling mill according to the present invention, in the above invention, the delay time set in the fourth procedure is set by a shift register in which a plurality of selectable items are individually stored. It is characterized by being done. That is, as one method, the shift distances (cm) of a plurality of items can be set in advance on the touch panel that constitutes the shift register. Thus, for example, if the speed AGC is set to be delayed by 50 cm in the process from deceleration to gradual movement, it is possible to suppress the positive fluctuation of the plate thickness caused by the oil film effect after the gradual constant velocity. In addition, during acceleration, experience shows that there is less delay in rolling speed than during deceleration.
By setting the delay distance of the GC to about 5 cm, it is possible to suppress the negative fluctuation of the plate thickness caused by the oil film effect.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A plate thickness control method for a steel plate rolling mill according to the present invention will be described below with reference to the drawings. First, speed effect compensation, which is a key to the speed control of the present invention, will be described. Normally, in a cold rolling mill, due to the oil film effect of rolling oil, the amount of rolling oil supplied increases as the rolling speed increases, and the oil film becomes thicker. As the temperature becomes slower, the amount of rolling oil supplied decreases and the oil film becomes thinner, so the plate thickness on the delivery side becomes thicker. Therefore, in the cold rolling mill, the oil film effect component becomes a disturbance, so the rolling gap of the steel strip rolling mill is corrected to be wide so that the strip thickness on the delivery side does not become thin as the rolling speed increases.

Such correction is performed by turning on / off the AGC output.
It is always done regardless of FF. Further, in the aluminum foil rolling mill, the oil film effect is used to change the speed to control the strip thickness on the delivery side. Compensation of the plate thickness for controlling the plate thickness by such speed change is called speed effect compensation (speed AGC). Therefore, the speed AGC is a plate thickness control amount that is fed back according to the rolling speed in order to control the fluctuation of the plate thickness due to the speed.

Next, a method of controlling the plate thickness by the speed AGC will be described. The relationship between the rolling speed of the rolling mill and the fluctuation of the outlet plate thickness is non-linear. Further, the characteristics of the variation relationship between the rolling speed and the delivery side plate thickness also differ depending on the material of the steel plate to be rolled. Therefore, in the system of the present invention, the characteristic curve of the rolling speed and the delivery side plate thickness variation can be set by the interpolation table. For example, an interpolating table in which the relationship between the rolling speed and the variation of the outgoing side plate thickness is set at 9 points is prepared, and the sheet thickness depending on the rolling speed is controlled based on each set point of this interpolating table. Also, such an interpolation table is
The number of 0 is prepared, and the interpolation table is properly used according to the material such as the steel plate to be rolled.

FIG. 1 is a diagram showing the control principle of a rolling mill which performs speed effect compensation in the present invention. In FIG. 1, the steel sheet 1 is rolled while passing through a rolling mill 2 along the sheet passing direction indicated by the arrow in the figure. At this time, the thickness of the steel plate 1 is measured by the left thickness meter 3 and the right thickness meter 4. In addition, an interpolation table 5 showing the relationship between the rolling speed and the delivery side plate thickness variation value is prepared in advance, and according to the rolling speed detected by a speedometer (not shown), the corresponding exit side sheet thickness variation value is used to calculate the rolling gap. The change amount (ΔS) is read. And
The rolling gap change amount (ΔS) is compared with a predetermined reference value (G1) and the deviation is output, and the cylinder 7 of the rolling mill 2 is controlled based on the gap reference value 6.
As a result, the cylinder 7 is rolled by the rolling mill 2 according to the rolling speed.
Since the amount of gap is controlled, the plate thickness of the steel plate 1 is controlled.

In addition to such control of the plate thickness by the speed AGC, acceleration / deceleration is performed in a state where the control of the speed AGC is cut off, and the input / output side plate thickness, load, material deformation resistance coefficient and MILL
It is also possible to obtain the amount of change (ΔS) in the rolling gap from a constant or the like and store the data in the interpolation table to correct the plate thickness.

Here, fluctuations in the inflow / outflow amount of rolling oil tend to lag behind fluctuations in the rolling speed. Therefore, the variation of the delivery side plate thickness due to the oil film effect tends to lag the variation of the rolling speed. Therefore, when the speed changes from deceleration to gradual movement, it is necessary to delay the speed AGC by the delay time. The time for delaying the speed AGC is measured by the change in the thickness of the steel sheet caused by the speed fluctuation of the rolling line,
The delay time is obtained from the speed fluctuation corresponding to the measured thickness change. And in the time from deceleration to slow motion,
The speed AGC is delayed by the shift register by the calculated delay time.

FIG. 2 is a flowchart for delaying the speed AGC when the speed changes from deceleration to slow motion. Figure 2
First, when the deceleration of the rolling speed is completed (step S1), the shift register delays the time by the delay time obtained from the speed fluctuation corresponding to the thickness change (step S2). When the delay is completed for a predetermined time (step S3), the amount of the speed AGC during the slow motion is changed to the amount of the speed AGC during the acceleration (step S4).

Thus, using the shift register,
By simulatingly shifting the rolling speed from the deceleration to the slow side to the delay side, it is possible to match the time during which the speed AGC is fed back with the time during which the outgoing side plate thickness fluctuates. Therefore, it is necessary to detect the rolling speed. With this, it is possible to properly control the plate thickness. At this time, if the shift amount of the shift register is individually set in the touch panel for each acceleration or deceleration, a desired delay time can be set by operating the touch panel to manage the plate thickness. . For example, if the setting parameter is a unit of distance, c
The plate thickness can be controlled in units of m.

Further, the output characteristics of the speed AGC may be individually set in consideration of the change of the characteristics of the oil film effect during acceleration or deceleration.
For example, when "0" is set in the "speed characteristic NO." On the touch panel, the characteristic registered in the 0 pattern is output during deceleration, and the characteristic pattern is automatically switched to another characteristic pattern during acceleration. Further, the content of each pattern may be arbitrarily variable by, for example, a preset internal constant of the controller.

FIG. 3 is a conceptual diagram of the operation of the rolling mill utilizing the speed effect compensation in the present invention. In FIG. 3, the steel plate 11 is configured to be rolled from the left reel 12 through the rolling mill 13 and wound on the right reel 14. Further, the steel plate 11 is appropriately tensioned by the left deflector roll 15 and the right deflector roll 16. Furthermore, the thickness of the steel plate 11 is measured by the left thickness meter 17 and the right thickness meter 18. On the other hand, rolling mill 1
3 includes a cylinder 19 that adjusts the gap to control the plate thickness of the steel plate 11, and a speedometer 20 that measures the rolling speed of the steel plate 11.

On the other hand, in the speed AGC control system, a plurality of rolling speed characteristics 21 indicating the characteristics of the rolling speed of the steel sheet 11 measured by the speedometer 20 and a plurality of shift amounts of the rolling speed during acceleration and deceleration are set. A tracking shift panel 22, a shift correction rolling speed characteristic 23 in which rolling characteristics are shift-corrected by a shift amount set in the tracking shift panel 22, and a changeover switch 24 for switching between rolling speed deceleration / acceleration. Acceleration pressure reduction characteristic 2 showing the pressure reduction characteristic of the cylinder 19 by the speed AGC during acceleration
5 and a reduction amount characteristic 26 during deceleration showing a reduction amount characteristic of the cylinder 19 by the speed AGC during deceleration.

Since the normal rolling operation of the rolling mill shown in FIG. 3 is known, the description thereof is omitted and the control operation of the plate thickness by the speed AGC will be described. Steel plate 11 is rolling mill 13
After passing, the rolling speed is measured by the speedometer and the rolling speed characteristic 21 is drawn. Here, by the tracking shift panel 2, a predetermined shift amount (for example, n +
When 1) is pressed and set, a shift correction rolling speed characteristic 23 showing a rolling speed curve shift-corrected by the tracked shift amount (n + 1) is obtained.

Here, if the steel plate 11 is decelerating, the changeover switch 24 is switched to the decelerating side, and the speed-up reduction amount characteristic 25 showing a reduction amount curve by speed effect compensation during acceleration.
Is obtained. Then, when the data of the acceleration reduction characteristic 25 is transmitted to the cylinder 19, the pressing force of the cylinder 19 is controlled by the amount of the acceleration reduction during deceleration. As a result, the rolling force in the rolling speed characteristic (that is, the shift correction rolling speed characteristic 23) shifted by the tracked shift amount (n + 1) is applied to the steel sheet 11. In this way, the rolling force corrected for the delay of the oil film effect is applied to the steel plate 11, so that the plate thickness of the steel plate is accurately controlled.

On the other hand, if the steel plate 11 is accelerating, the changeover switch 24 is switched to the accelerating side, and the reduction amount characteristic 26 during deceleration showing the reduction amount curve by the speed effect compensation during deceleration is obtained. Then, when the data of the reduction amount characteristic 26 during deceleration is transmitted to the cylinder 19, the pressing force of the cylinder 19 is controlled by the reduction amount during deceleration during acceleration. As a result, the rolling force in the rolling speed characteristic (that is, the shift correction rolling speed characteristic 23) that is shift-corrected by the tracked shift amount (n + 1) is applied to the steel sheet 11. That is, since the rolling force corrected for the delay of the oil film effect is applied to the steel plate 11, the plate thickness of the plate thickness is accurately managed.

FIG. 4 is an actual measurement characteristic diagram showing suppression of plate thickness variation during acceleration / deceleration. The horizontal axis of the figure shows the passage of time, and the vertical axis shows the variation amount of each data. This characteristic diagram shows "a characteristic of suppressing the variation of the plate thickness when accelerating and decelerating the sheet in 304E material (8 / 8PASS)". Explaining from the left side of the figure over time, when the rolling speed i decreases,
The simulated rolling speed j after the shift, which is shifted in the delay direction, is also decelerated accordingly. At this time, the speed AGC output k supplied to the cylinder 19 for controlling the rolling gap thickness increases with the deceleration of the simulated rolling speed j after the shift. That is, as the rolling speed i slows down (therefore, the simulated rolling speed j after shifting slows down), the amount of rolling oil decreases and the oil film becomes thinner. Speed A supplied (feedback) to the cylinder 19 by that amount
The GC output k is increased to narrow the gap. Thereby, the outlet side thickness deviation n is controlled to a constant value in accordance with the inlet side thickness deviation m.

Here, since a desired shift distance (cm) is set in advance by the touch panel (that is, the tracking shift panel 22 in FIG. 3), after the rolling speed i shifts from deceleration to gradual movement, The simulated rolling speed j of 1 is delayed by the time corresponding to the shift distance q until the slow motion is reached. That is, the simulated rolling speed j after the shift is still decelerating when the rolling speed i becomes slow. Therefore, the fed back speed AGC output k also continues to increase and narrows the gap.

As a result, the speed AGC output k continues to narrow the gap even if the rolling oil decreasing tendency is delayed from the rolling speed i decreasing speed and the plate thickness is changed due to the oil film effect. k can compensate the delay time of the oil film effect and control the plate thickness to be constant. Then, after the shift distance q, the simulated rolling speed j after shifting reaches a gradual slowdown, so that the speed AGC output k also becomes a constant value. In this way, even if the fluctuation of the rolling oil lags the fluctuation of the rolling speed i, the speed AGC output k compensates for the delay time and the output side thickness deviation n is set to a constant value according to the input side thickness deviation m. Have control over. Further, in the process of increasing the rolling speed i, the simulated rolling speed j after the shift increases in accordance with the rolling speed i, the speed AGC output k is decreased, and the gap is widened by the amount of thickening of the oil film. The output side thickness deviation n is controlled to a constant value according to the side thickness deviation m.

The characteristics shown in FIG. 4 are merely an example, but by arbitrarily setting the shift distance q for each material and reduction amount,
Even after the rolling speed i becomes the gradual constant speed, the speed AGC output k can be changed to suppress the point of plate pressure fluctuation due to the time delay of the oil film effect. In the example of FIG. 4, the shift distance set by the touch panel was 50 cm during deceleration and 0 cm during acceleration.

As in the embodiment shown in FIG. 4, by delaying the speed AGC output by a predetermined distance (for example, 50 cm) during deceleration, it is possible to suppress the positive fluctuation of the plate thickness after the gradual constant speed. In addition, the negative fluctuation of the plate thickness during acceleration is empirically less delayed in the rolling speed than that during deceleration. Therefore, even if the delay distance of the speed AGC output is 0 cm during acceleration, the negative fluctuation of the plate thickness is sufficiently suppressed. be able to. Since there is a slight delay during acceleration, the speed AGC
It is desirable to delay the output by, for example, about 5 cm. The above results are based on the above-mentioned "304E initial plate thickness 3 mm".
The result is.

The rolling speed varies depending on the material of the material to be rolled and the amount of reduction.
The shift amount set on the tracking shift panel (speed A
It is necessary to decide GC). By the way, the same "304
Even in the case of "material", in the case of "initial plate thickness 2 mm", the optimum plate thickness could be controlled with a delay amount of 35 cm during deceleration and 0 cm during acceleration. This is considered to be due to the difference in the amount of reduction in the final bus.

The embodiment described above is an example for explaining the present invention, and the present invention is not limited to this embodiment, and various modifications can be made within the scope of the gist of the invention. is there. For example, the above-described embodiment has explained the method of performing the plate thickness control by delaying the speed AGC, but if the delay of the speed AGC and the suppression of the tension fluctuation by the load current control according to the inertial force are used together, Further, the plate thickness can be controlled with high accuracy.

[0031]

As described above, according to the plate thickness control method for a steel plate rolling machine of the present invention, the delay time obtained from the speed fluctuation corresponding to the thickness change at the time of speed fluctuation from deceleration to slow motion. Only the timing at which the speed AGC is output is delayed. Thereby, even if the fluctuation of the inflow / outflow of the rolling oil is delayed from the fluctuation of the rolling speed, the fluctuation of the plate thickness due to the oil film effect can be suppressed.

For example, by delaying the speed AGC by 50 cm in the process from deceleration to gradual movement, it is possible to suppress the positive variation of the plate thickness caused by the oil film effect after the gradual constant velocity. In addition, during acceleration, the delay in rolling speed is less than that during deceleration from experience, so if the delay distance of the speed AGC is set to about 5 cm during acceleration,
It is possible to suppress the negative fluctuation of the plate thickness caused by the oil film effect. By such delay control of the speed AGC, it is possible to construct a steel plate rolling machine capable of managing the plate thickness of the steel plate with high accuracy.

[Brief description of drawings]

FIG. 1 is a diagram showing a control principle of a rolling mill that performs speed effect compensation in the present invention.

FIG. 2 shows the speed AG when the speed changes from deceleration to slow motion.
It is a flowchart which delays C.

FIG. 3 is an operation conceptual diagram of a rolling mill using velocity effect compensation in the present invention.

FIG. 4 is a measured characteristic diagram showing suppression of plate thickness variation during acceleration / deceleration.

[Explanation of symbols]

1 ... steel plate, 2 ... rolling machine, 3 ... left thickness gauge, 4 ... right thickness gauge,
5 ... Interpolation table, 6 ... Gap reference value, 7 ... Cylinder, 11 ... Steel plate, 12 ... Left reel, 13 ... Rolling machine, 14
... right reel, 15 ... left deflector roll, 16 ... right deflector roll, 17 ... left thickness gauge, 18 ... right thickness gauge, 19
... Cylinder, 20 ... Speedometer, 21 ... Rolling speed characteristic, 22
... tracking shift panel, 23 ... shift correction rolling speed characteristic, 24 ... changeover switch, 25 ... rolling reduction characteristic during acceleration, 26 ... rolling reduction characteristic during deceleration.

Claims (4)

[Claims] 1. A plate thickness control method for a steel plate rolling machine, wherein a plate thickness control amount according to a rolling speed is fed back by cold rolling to roll a steel plate, wherein a delay time of a change in the plate thickness of the steel plate with respect to a rolling speed. According to the above, a delay time of feedback of the strip thickness control amount is set, and a strip thickness control method for a steel strip rolling mill. 2. A first procedure for detecting a speed variation in a rolling line of the steel sheet rolling mill, and a second procedure for measuring a thickness variation of the steel sheet with respect to the speed variation detected in the first procedure. And the third step of obtaining the delay time of the sheet thickness change of the steel sheet with respect to the rolling speed based on the sheet thickness change amount measured in the second step, and the third step. A fourth step of setting the feedback delay time of the plate thickness control amount to the same value as the delay time.
The plate thickness control method of the steel plate rolling mill according to claim 1, wherein the plate thickness control of the steel plate is performed through the procedure of 1. 3. The speed fluctuation amount detected in the first procedure is a speed fluctuation amount when the rolling line speed changes from deceleration to slow motion which is the lowest constant speed. Item 3. A plate thickness control method for a steel plate rolling mill according to Item 2. 4. The delay time set in the fourth procedure is
The strip thickness control method for a steel strip rolling mill according to claim 2 or 3, wherein a plurality of selectable items are set by a shift register that is individually stored.