JP3334649B2 - Control method of temper rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for temper rolling of an annealed steel sheet in a rolling region in which rolling reduction cannot be stably performed due to having an inflection point of a material curve showing a relationship between a roll gap and a rolling force. The present invention relates to a method for controlling a temper rolling mill.

[0002]

2. Description of the Related Art Conventionally, regarding the method of controlling the elongation rate or the method of controlling the thickness of a temper rolling mill when temper-rolling an annealed steel sheet, actual elongation rate data is collected and based on the actual value. Feedback control (PID control) is performed (for example, Research Institute of Steelmaking No. 319 (1985), pp. 52-5).
9).

[0003] At the inflection point of the material curve showing the relationship between the roll gap and the rolling force, when the rolling force is continuously changed, the elongation and the plate thickness change rapidly. If the elongation or thickness changes suddenly, jumping of the elongation or thickness occurs to control the elongation or thickness positively, or the tension on the outlet side changes due to a sudden change in rolling force. Is generated.

In the conventional elongation rate control method or sheet thickness control method of the temper rolling mill, the control is performed without discriminating the inflection point of the material curve. Therefore, when the inflection point of the material curve is exceeded, the elongation and the plate thickness fluctuate rapidly at the inflection point of the material curve, and a jumping phenomenon of the elongation and the plate thickness occurs in an attempt to positively control it, or There is a problem that a sudden change in the rolling force causes a change in the tension on the delivery side.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems, and has been developed in consideration of the above-mentioned problems. To provide a control method of a temper rolling mill capable of discriminating extreme points and changing a control method of a temper rolling mill before and after an inflection point of a material curve to suppress fluctuation of elongation jumping and output side tension. Aim.

[0006]

Means of the present invention for solving the above problems are as follows.

In the first invention, when the temper rolling is performed on the steel sheet after annealing in the temper rolling mill, the inflection point of the material curve indicating the relationship between the roll gap and the rolling reduction is determined, and the inflection point of the material curve is determined. The method of controlling the temper rolling mill, wherein the elongation rate control method or the sheet thickness control method is changed before and after.

In a second aspect, in the first aspect, a frequency analysis is performed on the basis of time series data of a thickness, an elongation, a load, or a roll gap, and the respective response frequencies when the inflection point of the material curve is exceeded. The frequency intensity level of the nearby frequency band is previously determined and set, and the frequency band near the response frequency is analyzed by performing frequency analysis based on the time series data of the thickness, elongation, load, or roll gap at the time of temper rolling. And a discriminating point of a material curve is determined based on the obtained frequency intensity level and the preset frequency intensity level.

In a third aspect of the present invention, in the second aspect, when it is determined that the inflection point of the material curve is approached, the elongation is set in advance based on the intensity level of the frequency band near the response frequency obtained at the time of temper rolling. A method for controlling a temper rolling mill, wherein a control gain of rate control, a control gain of sheet thickness control, or a tension of a steel sheet is changed.

In the present invention, when the tempered steel sheet is subjected to temper rolling, the inflection point of the material curve is determined, and an elongation control method or a thickness control method of the temper rolling mill is provided before and after the inflection point. Since the change is made, it is possible to suppress the elongation jumping and the fluctuation of the outlet tension.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be further described.

FIG. 1 is a block diagram showing a control system of a temper rolling mill for explaining an embodiment of the present invention. FIG.
, S is a steel plate, 1 is a rolling roll, 2 is a hydraulic press-down device, 3a is an entrance bridle roll, 3b is an exit bridle roll, 4 is a thickness gauge, 5a is an entrance tension meter, 5b is an exit tension meter. , 6 is a rolling load cell, 7a is an infeed bridle plate feed length, 7b is an outgoing bridle plate feed length, 8 is an elongation calculating device, 9 is a frequency analyzer, and 10 is an inflection point for judging an inflection point of a material curve. Discriminating device, 11 is a mill control gain changing device, 12 is an incoming / outgoing side tension changing device, 13 is a rolling load control device, 14 is an elongation rate control device, 15 is a thickness control device,
16 is a selector for selecting one of the elongation rate control device 14 and the thickness control device 15 on the output side of the mill control gain changing device, 17a is an input tension control device, 17b is an output tension control device, and 18a is an input tension control device. The side speed control device 18b is a delivery speed control device.

In the temper rolling mill shown in FIG. 1, when the temper rolling is performed on the annealed steel sheet, the hydraulic pressing device 2 controls the rolling force and the inlet-side tension controller 17a and the outlet-side tension controller 17a.
b to control the input side tension and the output side tension, and
The feedback control is performed so that the elongation calculated by the equation (1) becomes a predetermined elongation or the steel sheet thickness detected by the thickness gauge 4 becomes the predetermined thickness. At that time, as explained below,
The inflection point of the material curve indicating the relationship between the roll gap and the rolling force is determined, and the temper rolling mill is controlled by changing the elongation rate control method or the sheet thickness control method.

When a jumping phenomenon occurs, its frequency is determined by the response of the feedback system. In the present invention, this frequency is called a response frequency. Further, when the frequency intensity at or near the response frequency exceeds a certain intensity, a jumping phenomenon occurs. Therefore, with respect to the time-series data of the sheet thickness, elongation, rolling force, and roll gap, the frequency intensity level of the frequency band near each response frequency is analyzed in advance to grasp the intensity level at which the jumping phenomenon occurs. Analyze the frequency intensity level in the frequency band near each response frequency of time series data of sheet thickness or elongation rate, rolling force or roll gap at the time of temper rolling, and the intensity level at which jumping phenomenon determined in advance occurs By comparing the magnitudes of the intensities with respect to, it is possible to determine whether or not the region where the jumping phenomenon occurs, that is, the vicinity of the inflection point or beyond the inflection point of the material curve.

In FIG. 1, the entrance bridle roll 3a
The feed length of the incoming roll of the rolling roll 1 and the feed length of the outgoing plate of the temper rolling mill are obtained from the number of rotations of the outgoing bridle roll 3b from the number of rotations of the roll. Calculate the rate. The time series data of the elongation calculated in the above, the roll gap detected from the position of the oil column of the hydraulic pressure reduction device 2, the thickness detected by the thickness gauge 4, the rolling load meter 6
Each time-series data of the rolling force detected in the step is analyzed by the frequency analyzer 9.
Output to

The frequency analyzer 9 analyzes the frequency intensity level of each frequency band near the response frequency based on the time series data of the input thickness, elongation, rolling force or roll gap. The result is output to the inflection point discriminating device 10.

[0017] In an inflection point discriminating unit 10, the thickness or elongation or rolling force or roll gap, the overall strength of the frequency intensity level S ₁ in advance frequency band f ₀ ~f ₁ and the frequency band of a particular region, respectively S _With respect to the ratio S ₁ / S _{0 to 0} , set values k ₁ and k _{2 of} two levels of high and low can be set. Set value k ₁ high level side is set to the inflection point of the material curve, set value k ₂ of the low level side is set to the inflection point near the material curve.

In the inflection point discriminating apparatus 10, a frequency analyzing apparatus is used.
The thickness or elongation or rolling force sent from 9
Is frequency analysis of time series data of roll gap
Determine the result. In other words, the frequency analysis data
Frequency band f ₀~ F₁Frequency intensity is low.
Bell-side set value k_TwoExceeds the set value k on the high level side₁Less than
In the case of, it is determined that the inflection point of the material curve is approaching,
High level setting value k ₁Inflection point of material curve
Is determined to be.

Hereinafter, a case where the inflection point of the material curve is determined by performing frequency analysis based on the time series data of the rolling force will be specifically described with reference to FIG.

In FIG. 2, (a) outputs the time series data of the rolling force measurement value of the rolling load cell 6, and (b) outputs the time series data of (a) to the frequency analysis device 9, and outputs the time series of the rolling force. It is the figure which extracted the frequency component which data has as a frequency spectrum from 0 to 500 Hz. The result is input to the inflection point discriminating device 10 for the material curve.

In the inflection point discriminating apparatus 10, the frequency band f _{0 to} f ₁ in the specific region is set to 200 to 400 Hz, and the ratio S ₁ / S ₀ of the frequency intensity S _{1 to} the total intensity S ₀ in this frequency band is set. The set value k ₁ on the high level side is set at a level where the ratio is 50%, and the set value k ₂ on the low level side is set at a level where the ratio S ₁ / S ₀ is 30%. Set value k ₁ high level side corresponds to the inflection point of the material curve, set value k ₂ of the low level side is set in the vicinity of the inflection point of the material curve.

If the measured value of the frequency intensity in the frequency band from 200 to 400 Hz of the frequency spectrum input to the inflection point discriminating apparatus 10 does not exceed the set value k ₂ (30%) on the low level side, the material curve changes. Judging that it is not near the pole,
If the set value k ₂ (30%) is exceeded, it is determined that the current value is near the inflection point of the material curve, and the set value k ₁ (50
%), It is determined to be the inflection point of the material curve.

The frequency bands f _{0 to} f _{1 in the} specific region and the frequency intensity levels k ₁ and k ₂ in this frequency band are in the vicinity of the response frequency of the time series data of the rolling force in or near the region where the jumping phenomenon occurs. It can be obtained by performing a frequency analysis.

FIG. 3 is a diagram showing an example of time series data of the elongation rate and a frequency spectrum of the time series data.
(A) is a diagram showing the time-series data of the measured elongation percentage of the elongation-ratio calculator 8, and (b) outputs the time-series data of (a) to the frequency analyzer 9 and has the time-series data of the elongation. FIG. 6 is a diagram extracted as a frequency spectrum in a predetermined frequency range.
The result is input to the inflection point discriminating device 10 for the material curve.
As in the case of the rolling force, the inflection point discriminating apparatus 10 is set with frequency bands f _{0 to} f _{1 in} a specific region of the elongation, and the ratio S of the frequency intensity S ₁ in this frequency band to the overall intensity S ₀ . A set value k ₁ corresponding to the level where ₁ / S ₀ corresponds to the inflection point of the material curve, and a set value k ₂ corresponding to the vicinity of the inflection point of the material curve are set to a lower level than the set value k ₁ . .

The inflection point discriminating device 10 judges that the frequency in the frequency band from f _{0 to} f ₁ of the input frequency spectrum does not exceed the set value k ₂ , it is not near the inflection point of the material curve, If the value exceeds the set value k ₂ is determined as near pole material curve, it is determined that the turning point may further exceeds the set value k _1.

The case where the inflection point of the material curve is determined by performing the frequency analysis based on the time series data of the sheet thickness or the roll gap can be performed in the same manner as described above.

The above judgment result is output from the inflection point discriminating device 10 to the mill control gain changing device 11 or the inlet / outlet side tension changing device 12.

The mill control gain changing device 11 determines that the mill elasticity curve is near or above the inflection point of the material curve based on the judgment result sent from the inflection point discriminating device 10 or determines that the mill elasticity curve exceeds the inflection point. If it is determined, the control gain of the elongation rate control device or the control gain of the plate thickness control device is set to a preset low gain, and the set low gain control gain is set via the selector 16 to the elongation rate control device. 14 and the control gain set in the elongation rate control device 14 is changed to a low gain to change the rolling load control device 1
The rolling load is controlled by 3 so that the elongation calculated by the elongation calculating device 8 becomes a predetermined elongation.

The frequency intensity is again set to the low level set value k.
_{When the value} falls below ₂ , the material inflection point discriminating device 10 determines that the mill elasticity curve is not near the inflection point of the material curve, and the mill control gain changing device 11 changes the control gain of the elongation rate control to the original high gain. The control gain is output to the elongation rate control device 14, the control gain of the elongation rate control device 14 is changed to the original high gain, the rolling load is controlled via the rolling load control device 13, and the elongation ratio calculation device 8 is controlled. The elongation rate calculated by is set to a predetermined elongation rate.

By performing such control, jumping of the elongation before and after the material curve can be prevented.

When the thickness control gain is changed, the selector 16 is switched to the thickness control device 15 to output the corrected control gain to the thickness control device 15 via the selector 16.
The control gain of the thickness control device 15 is changed to a low gain, and the rolling load is controlled by the rolling load control device 13 so that the thickness detected by the thickness gauge 4 becomes a predetermined thickness.

When the frequency intensity again falls below the set value k ₂ , the material inflection point discriminating device 10 judges that the mill elasticity curve is not near the inflection point of the material curve, and the mill control gain changing device 11 performs the sheet thickness control. Is changed to the original high gain, the control gain is output to the sheet thickness control device 15, the control gain of the thickness control device 15 is changed to the high gain, and the rolling load is controlled via the rolling load control device 13. Is controlled so that the thickness detected by the thickness gauge 4 becomes a predetermined thickness.

By controlling in this way, it is possible to prevent the thickness from fluctuating before and after the material curve.

The result of the judgment by the inflection point discriminating device 10 can be outputted to the entrance / outlet tension changing device 12. The entrance / exit-side tension changing device 12 has a
The entrance tension and the exit tension are set in advance. The input / output side tension changing device 12 changes the input side tension and the output side tension by a certain fixed ratio with respect to a preset tension based on the judgment result sent from the inflection point discriminating device 10. Then, while outputting to the entrance-side tension control device 17a and the exit-side tension control device 17b, the hydraulic pressure reduction device 2 reduces the rolling force and the entrance-side tension and the exit-side tension with the entrance-side tension control device 17a and the exit-side tension control device 17b. The control is performed such that the elongation calculated by the elongation calculating device 8 becomes a predetermined elongation or the steel plate thickness detected by the thickness gauge 4 becomes the predetermined thickness.

According to the present invention, the inflection point of the material curve can be determined early and accurately during rolling. As a result, it is possible to suppress the occurrence of elongation jumping and sheet thickness jumping that occur at the inflection point of the material curve in the low rolling region of the wet rolling or the high elongation rolling region of the dry rolling, and the occurrence of quality abnormality due to this can be suppressed. Can be prevented.

In FIG. 1, the temper rolling mill is an example of a single stand, but the temper rolling mill may be a multi-stage stand. In the case of a multi-high rolling mill, the tension between stands is set in advance in addition to the input side tension and the output side tension, and based on the judgment result sent from the inflection point discriminating apparatus, the input side tension and the output side tension are determined. The tension and the stand-to-stand tension may be changed to preset tensions.

[0037]

According to the present invention, the inflection point of the material curve is determined, and the method of controlling the elongation percentage or the thickness of the steel sheet after annealing before and after the inflection point is changed based on the determination result. It is possible to suppress the occurrence of the elongation jumping and the thickness jumping that occur when exceeding the inflection point of the material curve, and to prevent the occurrence of the quality abnormality caused by these.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a control system of a temper rolling mill for explaining an embodiment of the present invention.

FIG. 2 is a diagram showing time-series data of a measured value of a rolling force and a spectrum of a frequency component thereof.
(B) shows a frequency spectrum.

FIGS. 3A and 3B are diagrams showing time-series data of measured elongation percentages and spectra of their frequency components, wherein FIG.
(B) shows a frequency spectrum.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roll roll 2 Hydraulic pressure reduction device 3a Inlet bridle roll 3b Outlet bridle roll 4 Thickness gauge 5a Inlet tensiometer 5b Outlet tensiometer 6 Rolling load meter 7a Inlet bridle plate sending length 7b Outlet bridle plate sending length 8 Elongation rate calculator 9 Frequency analyzer 10 Inflection point discriminator 11 Mill control gain changer 12 Inlet / outlet tension changer 13 Rolling load controller 14 Elongation rate controller 15 Sheet thickness controller 16 Selector 17a Inlet-side tension control Device 17b Outlet tension control device 18a Inlet speed control device 18b Outlet speed control device S Steel plate

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B21B 37/18 BBQ B21B 37/08 BBH 37/56 BBQ (56) References JP-A-2000-140918 (JP, A) 7-75803 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 37/00-37/78

Claims (3)

(57) [Claims] When a temper rolling is performed on a steel sheet after annealing in a temper rolling mill, an inflection point of a material curve showing a relationship between a roll gap and a rolling force is determined, and before and after the inflection point of the material curve. A method for controlling a temper rolling mill, comprising changing an elongation rate control method or a sheet thickness control method. 2. A frequency intensity level of a frequency band near each of the response frequencies when a frequency curve is inflected based on time series data of a sheet thickness, an elongation rate, a load, or a roll gap. Is determined and set in advance, and the strength level of the frequency band in the frequency band near the response frequency is determined by performing frequency analysis based on the time series data of the sheet thickness or the elongation rate or the load or the roll gap during the temper rolling, The method according to claim 1, wherein an inflection point of a material curve is determined based on the obtained frequency intensity level and the preset frequency intensity level. 3. When it is determined that the inflection point of the material curve is approached, a control gain or a sheet thickness of a preset elongation rate control is set based on an intensity level of a frequency band near a response frequency obtained at the time of temper rolling. The control method for a temper rolling mill according to claim 2, wherein the control gain of the control or the tension of the steel sheet is changed.