JPH09267111A - System for specifying primary factor of thickness variation in rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove the effect of thickness variation on the inlet side and to exactly specify the caused of thickness variation by specifying peak frequencies over the upper limit value preset and, when they are within a setting range specifying a roll in accordance with the variable frequency as the primary factor of variation. SOLUTION: In the 5th arithmetic part 12, a certain ceiling value curve is set as the function of frequency and the peak frequencies on a level over the ceiling value curve in the frequency component signal determined with the 3rd arithmetic part 10 are specified as there is abnormal variation. Next, in the specified peak frequencies, the variable frequencies calculated with the 4th arithmetic part 11 which are within the range of preset frequency is thought that it is generated with correspondent roll and the roll is judged as abnormal. That result is outputted to a display 13 and an alarm 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip thickness variation factor identifying system in a rolling mill equipped with a strip thickness control system, and more particularly to frequency analysis of strip thickness variation on the inlet side and outlet side and output from the inlet side of the rolling mill. The present invention relates to an identification system that automatically and continuously identifies a variation factor by using a transfer function to the side.

[0002]

2. Description of the Related Art Conventionally, in hot and cold rolling equipment, when an abnormal variation in the outgoing strip thickness appears, attention is paid to the frequency of the strip thickness in identifying the abnormal variation.
This was done by comparing with the rotation speed of the work roll. An example thereof is disclosed in Japanese Patent Laid-Open No. 59-61518. In addition, JP-A-5-200
Japanese Patent Laid-Open No. 42-42 discloses a plate thickness gauge which is arranged on each of the inlet side and the outlet side of a rolling mill and measures the thickness of a rolled plate, and a frequency analysis device which analyzes a plate thickness time-series signal from the thickness gauge. An example is provided for identifying the cause of the abnormality.

[0003]

However, in Japanese Patent Laid-Open No. 59-61518, the frequency component of work roll eccentricity or partial deformation is analyzed by frequency analysis of strip thickness time series signals only on the rolling mill exit side. Since it is trying to identify, it is not possible to remove the existing contribution of the thickness variation on the inlet side, which may lead to an erroneous judgment. Further, in Japanese Patent Laid-Open No. 5-20042, the difference between the frequency analysis results of the outgoing side plate thickness and the incoming side plate thickness is taken to remove the influence of the incoming side plate thickness variation, but the existence of a rolling plate thickness control system exists. Since it is not taken into consideration, it cannot be applied to the actual operation in which the inlet side plate thickness variation is changed by the plate thickness control system and becomes the output side plate thickness variation.

The present invention has been made to solve such a problem, and the effect of the strip thickness control system applied in the actual operation is expressed as a transfer function from the inlet side to the outlet side of the rolling mill. In consideration of the above, a system for identifying the factors of variation in strip thickness in a rolling mill that enables accurate determination of the cause of variations in strip thickness by accurately removing the influence of variations in strip thickness from the frequency analysis result of variations in strip thickness The purpose is to provide.

[0005]

A plate thickness variation factor specifying system in a rolling mill according to the present invention comprises an inlet side plate thickness gauge for measuring the thickness of a rolled plate on the inlet side of a rolling mill, and rolling on the outlet side of a rolling mill. An output side thickness gauge for measuring the thickness of the strip, a first calculation unit for obtaining a transfer function from the inlet side to the outlet side of the rolling mill before starting rolling based on a setting parameter of the thickness control system, and an input side thickness gauge From the second calculation unit for calculating the estimated time-series signal of the output side thickness by multiplying the time-series signal of the input side plate thickness from the transmission characteristic obtained by the first calculation unit, and the output side plate thickness from the second calculation unit. Frequency analysis device for analyzing the estimated time-series signal of, the second frequency analysis device for analyzing the time-series signal of the output-side plate thickness from the output-side thickness gauge, and the output-side plate thickness obtained by the second frequency analysis device Actual frequency characteristics of fluctuations and output side plate thickness obtained by the first frequency analyzer A fourth arithmetic unit for obtaining a third calculation unit for obtaining a difference between the estimated frequency characteristic of the dynamic, the influence variation frequency is delivery side thickness fluctuation of the rolls constituting the rolling mill,
A peak frequency exceeding a preset upper limit value is specified from among the frequency component signals obtained by the third computing unit, and the peak frequency falls within the preset range of the fluctuation frequency obtained by the fourth computing unit. In some cases, it has a fifth calculation means for identifying the roll corresponding to the relevant fluctuating frequency as a factor of fluctuation.

In the present invention, the first calculation unit calculates the transfer function from the inlet side to the outlet side of the rolling mill by taking in the setting parameters of the strip thickness control system set before the start of rolling. Next, the second arithmetic unit multiplies the inlet side thickness variation measured by the inlet side thickness gauge by the transfer characteristic calculated by the first arithmetic unit to estimate a time series signal of the outlet side thickness. Furthermore the third
In the calculation unit, the actual frequency characteristic of the output side plate thickness variation analyzed by the second frequency analysis device and the estimated time series signal of the output side plate thickness obtained by the second calculation unit are analyzed and obtained by the first frequency analysis device. The difference with the estimated frequency characteristic of the obtained outgoing side plate thickness variation is obtained.
In this way, the contribution of the inlet-side thickness variation included in the outlet-side thickness variation, which was problematic in the conventional method, can be completely canceled, and only the outlet-side thickness variation that depends on eccentricity or partial deformation of the work roll can be extracted. You can Among the frequency components of the output side plate thickness variation thus obtained, the peak frequency exceeding the preset upper limit value is regarded as an abnormal variation. 4th
The calculation unit calculates and obtains a fluctuation frequency in which each roll of the rolling mill fluctuates and affects the outlet plate thickness, and the fifth calculation unit calculates the peak frequency based on the actual measurement and the fluctuation frequency based on the calculation. If the two frequencies are close to each other within a predetermined range, it is concluded that the roll corresponding to the fluctuation frequency is the fluctuation factor.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall configuration diagram of a system showing an example of an embodiment of the present invention. In FIG. 1, 1
Is an entrance side plate thickness gauge provided on the rolling plate intake side of the rolling mill,
2 is an outlet plate thickness gauge provided on the rolled plate take-out side, 3, 4
Is a first and second frequency analysis device (FFT1, 2) for frequency-analyzing the plate thickness time-series signal, and 5 is a feedforward reduction position using the output of the inlet plate thickness gauge so that the outlet plate thickness deviation is zero. FF-AGC, 6 is a roll-down position control system that controls the roll-down position to the roll-down target position, and 7 is a feedback-type control of the roll-down position using the output of the output-side thickness gauge to reduce the output-side thickness deviation to zero. FB-AGC, 8, 9, 10,
Reference numerals 11 and 12 denote a first arithmetic unit, a second arithmetic unit, a third arithmetic unit, a fourth arithmetic unit and a fifth arithmetic unit, respectively, which are provided with a storage device and an arithmetic device and are automatically processed by a program. It consists of a computer. Reference numerals 13 and 14 are displays and alarms that are controlled by the fifth arithmetic unit to notify the abnormality, 15 is a pay-off reel, 16 is a tension reel, and 17 is a work roll (only one is shown in FIG. But the following arguments apply as well.)
It is. 2, FIG. 3, FIG. 4, FIG. 5, and FIG. 6 are the processes in the first arithmetic unit 8, the second arithmetic unit 9, the third arithmetic unit 10, the fourth arithmetic unit 11, and the fifth arithmetic unit 12, respectively. FIG. FIG. 7 is an explanatory diagram showing an example of problems in the conventional method.

Next, the operation of the system of FIG. 1 will be described with reference to FIGS.
This will be described with reference to FIG. Prior to the start of rolling, setup calculation is performed by the host computer, and the parameters of each AGC, which is the plate thickness control system, are set. In the first calculation unit 8, as shown in FIG. 2, this parameter is input, a predetermined calculation process is performed, and the coefficient of the transfer function (discrete time expression) G from the variation of the incoming plate thickness to the variation of the outgoing plate thickness. Output parameters.

Here, the concept for removing the influence of, for example, the FF-AGC 5 in the first arithmetic unit 8 will be described (the same applies when other AGCs are considered). Set the entrance side plate thickness etc. as follows. Rolling mill setting gap: S Inlet plate thickness: h _in Outlet plate thickness: h _out Rolling load: P Mill rigidity: K FF-AGC gain: G _FF FF-AGC operation is ΔS = G _FF · Δh _in .
However, Δ represents a deviation. Since the outlet side plate thickness deviation Δh _out is expressed by the following equation (1), the outlet side plate thickness h _out considering the influence of FF-AGC can be obtained from the inlet side plate thickness h _in .

[0010]

[Equation 1]

During rolling, the rolled plate 50 progresses from the entrance side to the exit side of the rolling mill, and the plate thickness of the rolled plate is taken in as a time series signal of the plate thickness deviation by the entrance side plate thickness meter 1 and the exit side plate thickness meter 2. Be done. As shown in FIG. 3, the second calculation unit 9 calculates the transfer function (discrete time expression, hereinafter the same) from the inlet side thickness variation to the outlet side thickness variation obtained by the first arithmetic unit 8 as the inlet side thickness gauge. It is applied to the time series signal of 1 to generate the estimated time series signal of the outgoing side plate thickness. The waveform of (a2) of FIG. 4 is this signal.

The time series signal (a
2) and the output (b) of the output side plate thickness gauge 2 are sent to the first and second frequency analyzers 3 and 4, respectively, and converted into frequency component signals. The signals are shown in (A) and (B) of FIG.
The frequency component signals (A) and (B) are input to the third calculation unit 10, and the output frequency component signal (A) estimated from the input side time series signal is subtracted from the output side frequency component signal (B). To be done. In addition, the 3rd calculating part 10 shall input a signal from the 1st and 2nd frequency analyzers 3 and 4 for every fixed period. In this way, it is possible to completely cancel the influence of the variation of the inlet plate thickness, which has been a problem in the conventional method.

Here, a case where there is a problem in the conventional method will be described with reference to FIG. The problem arises when the frequency of the variation of the thickness of the inlet side and the frequency of the variation of the thickness of the outlet side due to the roll eccentricity are close to each other. When the inlet side plate thickness variation as shown in (a) in FIG. 7 is input, the inlet side plate thickness variation becomes almost zero by the control by the FF-AGC5 and FB-AGC7 as shown in FIG. If the output side thickness fluctuation reappears due to roll eccentricity and both fluctuation frequencies are close to each other, simply obtain the difference between the output side thickness frequency analysis result and the input side thickness frequency analysis result. No longer has a peak indicating roll fluctuation. In such a case, if the present invention is applied, as shown in FIG. 4, it is possible to accurately detect the peak indicating the roll fluctuation and correctly specify the fluctuation factor.

Next, as shown in FIG. 5, the fourth computing unit 11 determines the roll diameter of each roll 17 (only one roll is shown in the drawing) of the rolling mill and the rolling speed (the delivery side plate speed at the final stand). ), And the peripheral speed Vm of each roll
i (i is the stand No.) is calculated, and the variation frequency fmi of the outlet side plate thickness due to variation such as eccentricity of each roll or local expansion is calculated from the following equation (2). fmi = n · Vmi / (π · Dmi) (2) where n = 1 or 2 fmi, Vmi, and Dmi are the fluctuating frequency and the roll peripheral velocity due to the fluctuation of the i-th stand roll from the entrance side, respectively. , The roll diameter. Further, if the rolling speed is constant, the frequency of the plate thickness fluctuation measured by the delivery side plate thickness gauge 2 of the final stand also has the same value as in the expression (2). Therefore, when the rotation speed of each roll 17 is known, the variation frequency fm of the outlet plate thickness may be calculated from the following equation (3). fmi = nωmi / (2π) (3) where n = 1 or 2 fmi and ωmi are the fluctuation frequency and the roll angular velocity due to the fluctuation of the roll of the i-th stand from the entry side.

In the fifth arithmetic unit 12, as shown in FIG. 6C, first, an upper limit curve is set as a function of frequency, and among the frequency component signals obtained by the third arithmetic unit 10. , It is specified that the peak frequency at a level exceeding this upper limit curve has an abnormal fluctuation. Next, as shown in FIG. 6D, the identified peak frequency E
1, E2, which is within a preset frequency range (shaded area in FIG. 6) of the fluctuation frequencies F1, F2, F3, etc. calculated by the fourth calculation unit 11, E1 in this example is It is considered to be caused by the corresponding roll, and that roll is judged to be abnormal. Then, the result is output to the display 13 and the alarm device 14. E2 is a fluctuation that cannot be explained by the eccentricity of the roll.

Considering the factors affecting the delivery side plate thickness in cold rolling, the plate thickness fluctuations generated in the previous process, the non-uniform deformation resistance generated in the previous process, the eccentricity of each roll constituting the rolling mill, the rolling The local expansion of each roll that constitutes the rolling mill, the action of each control system that configures the rolling mill, etc. can be considered. Of these, the sheet thickness variation caused by the present rolling mill is not strictly considered, but is strictly erased in consideration of the effects of the first computing unit 8, the second computing unit 9, and the third computing unit 10. As to the above, as described above, the factor can be specified by the present invention. ,
Is specified as a cause other than roll eccentricity and roll local expansion as in E2 above.

The arithmetic units 8 to 12 of the system shown in FIG.
The computer configuring the above may be provided for each computing unit, or one computing unit may execute the functions of the computing units.

[0018]

As described above, according to the present invention, the transfer function from the variation of the inlet plate thickness to the variation of the outlet plate thickness is explicitly considered, and the contribution of the inlet plate thickness variation to the outlet plate thickness variation is strictly determined. Since it can be removed, it is possible to specify the fluctuation factor of the fluctuation of the outgoing plate thickness extremely accurately.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a system showing an example of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of processing in a first calculation unit in FIG.

FIG. 3 is an explanatory diagram of processing in a second calculation unit in FIG.

FIG. 4 is an explanatory diagram of a process in a third calculation unit in FIG.

5 is an explanatory diagram of processing in a fourth arithmetic unit in FIG.

FIG. 6 is an explanatory diagram of processing in a fifth arithmetic unit in FIG.

FIG. 7 is a diagram showing an example of a problem in the conventional method.

[Explanation of symbols]

 1 Inlet side thickness gauge 2 Outlet side thickness gauge 3 First frequency analyzer (FF1) 4 Second frequency analyzer (FF2) 5 Feedforward type thickness control system 6 Rolling position control system 7 Feedback type thickness control system 8th 1 computing unit 9 2nd computing unit 10 3rd computing unit 11 4th computing unit 12 5th computing unit 13 display 14 alarm device 15 payoff reel 16 tension reel 17 work roll

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication B21B 37/66

Claims (1)

[Claims] 1. An inlet side plate thickness gauge for measuring the thickness of a rolled plate on the inlet side of a rolling mill, an outlet side plate thickness gauge for measuring the thickness of a rolled plate on the outlet side of a rolling mill, and setting parameters for a plate thickness control system. A first calculation unit for obtaining the transfer function from the inlet side to the outlet side of the rolling mill before starting rolling based on the above, and the first calculation unit for the time series signal of the inlet side plate thickness from the inlet side thickness gauge.
A second arithmetic unit that multiplies the transfer characteristics obtained by the arithmetic unit to calculate an estimated time series signal of the outlet side plate thickness, and a first arithmetic unit that analyzes the estimated time series signal of the outlet side plate thickness obtained by the second arithmetic unit. 1 frequency analyzer, a second frequency analyzer for analyzing a time series signal of the outlet plate thickness from the outlet plate thickness gauge, and an actual frequency characteristic of the outlet plate thickness variation obtained by the second frequency analyzer, A third method for obtaining a difference from the estimated frequency characteristic of the outgoing side plate thickness variation obtained by the first frequency analysis device
An arithmetic unit, a fourth arithmetic unit that obtains a variation frequency in which the variation of each roll that constitutes the rolling mill influences the outlet plate thickness, and a frequency component signal that is obtained by the third arithmetic unit and is preset. A peak frequency that exceeds the upper limit value is specified, and if the corresponding peak frequency is within a preset range of the fluctuation frequency obtained by the fourth computing unit, a roll corresponding to the fluctuation frequency is specified as a fluctuation factor. 5. A strip thickness variation factor identification system in a rolling mill, comprising: