KR100815445B1 - Method for roll eccentricity detection by band pass filtering - Google Patents

Abstract

The present invention relates to a method for detecting a roll eccentric component caused by a difference between a rotational center and a geometrical center of a roll in a rolling process.

According to the present invention, the method comprising: receiving a steel plate input signal and a marker pulse signal generated every roll rotation; Synchronizing the rolling load with a predetermined sample pulse signal to store the rolling load value until the roll makes one revolution; Calculating a load change by calculating an average value for the load signal from the rolling load value to one revolution and removing the average load signal from each stored load; Performing band pass filtering from the stored rolling load, separating the roll eccentricity for each frequency from the result of the band pass filtering, and outputting the magnitude of the eccentricity for each frequency; Composing a roll eccentric control signal by synthesizing a fundamental wave and a double wave to the eccentric magnitude output value for each frequency, and using this as an eccentric control value; It provides a roll eccentric component detection method of the rolling mill comprising a.

Roll, eccentric, rolling, band pass

Description

Roll eccentricity detection method of rolling mill using band pass filter {Method for roll eccentricity detection by band pass filtering}             

1 is a block diagram of an eccentric detection apparatus using a band pass filter according to an embodiment of the present invention,

2 is a flowchart illustrating a process for performing a roll eccentric detection method according to an embodiment of the present invention.

※ Explanation of code about main part of drawing ※

101: angle detector 102: eccentric synthesis unit

103: signal input unit 104: data processing unit

105: eccentric detection unit 106: thickness controller

107: position controller

The present invention relates to a method for detecting a roll eccentric component caused by a difference between a rotational center and a geometrical center of a roll in a rolling process, and more specifically, backs up a pulse generator such as a pulse generator (PLG). By acquiring the pulse signal and the rolling load signal in synchronization with each other, the digital signal is extracted from the rolling load data through a plurality of digital band pass filters configured in parallel to classify the eccentricity according to the cause and to control the eccentricity. It relates to a roll eccentric detection method utilized for.

The problem of thickness variation caused by roll eccentricity in the rolling process is very important. In particular, in the case of rolling a thin plate such as D & I (Drawing & Ironing) material in the hot rolling process, the short-cycle thickness variation due to the roll eccentricity has a great influence on the defect of the product.

The roll eccentricity is caused by various causes, and it is caused by the component corresponding to the rotation frequency generated by the key of the roll bearing, the double frequency component of the rotation frequency generated by the elliptic roll, and the deformation caused by the thermal expansion of the roll. Although it is shown as the harmonic component by, in general, the part by the fundamental wave and the double wave has the greatest influence, and in the case of performing the eccentric control, only the fundamental wave and the double wave are often controlled.

As a method for detecting roll eccentricity using a band pass filter from a rolling load signal, a technique described in the US Patent 'Method and appratus for the detection and correction of roll eccentricityl' (US Patent: 4,910,985) and a Korean patent 'Eccentricity of the rolling mill' Techniques such as those described in 'Diagnostic Methods and Apparatus (Application No. 10-2000-0067576)' are widely used. However, in these methods, band pass filtering is performed on data acquired at regular time intervals. In order to continuously change the center frequency of the pass filter, information such as a tachometer is used, and there is a problem that correction of the number of data for filtering is necessary.

In other words, there is an urgent need in the art for a method for accurately detecting roll eccentricity without requiring center frequency correction of band pass filtering regardless of rolling speed fluctuations.

An object of the present invention for solving the problems of the prior art as described above is to provide an operator with separate detection of the roll eccentric component generated by the difference between the rotational center and the geometric center of the roll in the rolling process by the cause of the eccentricity, It is to provide a roll eccentric detection method that provides accurate information on the status of the backup roll and utilizes the detection result for eccentric control.

In order to achieve the above object, according to the present invention, in the method for detecting the roll eccentric component generated by the difference between the rotational center and the geometrical center of the roll during the rolling process, a steel sheet input signal and a marker pulse generated every roll rotation Receiving a signal; Synchronizing the rolling load with a predetermined sample pulse signal to store the rolling load value until the roll makes one revolution; Calculating a load change by calculating an average value for the load signal from the rolling load value to one revolution and removing the average load signal from each stored load; Performing band pass filtering from the stored rolling load, separating the roll eccentricity for each frequency from the result of the band pass filtering, and outputting the magnitude of the eccentricity for each frequency; Composing a roll eccentric control signal by synthesizing a fundamental wave and a double wave to the eccentric magnitude output value for each frequency, and using this as an eccentric control value; It provides a roll eccentric component detection method of the rolling mill comprising a.

Hereinafter, a roll eccentric detection method of a rolling mill using a band pass filter according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an eccentric detection apparatus using a band pass filter according to an embodiment of the present invention, wherein the eccentric detection apparatus includes an angle detector 101, an eccentric combining unit 102, a signal input unit 103, and a data processing unit. 104, an eccentric detector (frequency and magnitude for each frequency 105), a thickness controller 106 and a position controller 107.

The signal input unit 103 and the angle detector 101 carry out rolling loads from a load cell, marker pulses generated every revolution from a pulse generator attached to a backup roll, and a predetermined rotation angle from the pulse generator through a counter board. It is the part that stores the rolling load in synchronization with each pulse after input. The pulse generator used in one embodiment of the present invention generates one marker pulse and 64 sample pulses for each rotation, but this may be different for each applied system.

The data processing unit 104 obtains an average of the rolling load signals by taking an appropriate window from the stored rolling load signals in synchronization with the pulse, removes the average value from each rolling load, and calculates and stores the load variation value. Then, band pass filtering is performed from the stored load averages. A window for data processing generally takes a window for data while the roll is rotating, and the window is moved each time the roll is rotated. Also, band pass filtering is performed in this part using a plurality of digital filters. The filtering is performed while passing through a band pass filter each configured in series in the rolling load deviation, and the output value of each band pass filter means an eccentric component detected according to the center frequency.

The following describes a number of band pass used in the present invention. In the present invention, a plurality of band pass filters are used to detect only the roll eccentric component from the rolling load signal, and each center frequency is set differently in connection with the cause of the roll eccentricity.

A band pass filter with a center frequency of 1 Hz is used to detect only fundamental wave components generated by a backup roll key, etc. A band pass filter with a center frequency of 2 Hz is used to detect only double wave components generated by an ellipsoid. Use Then, bandpass filters having different center frequencies are used to detect each harmonic component.                     

In addition, in the present invention, since a load signal corresponding to a certain angle is acquired, it is not necessary to correct the center frequency according to the speed as in other inventions. The digital band pass filter used here is designed as follows.

Assuming that the center frequency is w ₀ and B is the bandwidth, a second analog Butterworth equation such as Equation 1 below is derived.

The discretization of Equation 1 leads to Equation 2 below.

In the above equation, H (s) denotes the transfer function of the filter in the continuous system, H (z) denotes the transfer function of the filter in the discrete system, s denotes the Laplace transform, and z denotes the z-conversion operator. In the above equations, A ₁ , A ₂ , B ₀ , and c are parameters having no special physical meanings generated during the conversion from the continuous system to the discrete system [H (s)-> H (z)]. In addition, T _s is a sampling time in the case of sampling at a predetermined time interval, but is defined as an angle occupied by one sample for one rotation angle since the sampling corresponds to a certain angle.

Next, the eccentric detection section 105, which classifies the output of each band pass filter, detects the magnitude and phase of the eccentricity for each cause of the eccentricity. From the output here, it is possible to know the magnitude of the influence according to the cause of the eccentricity, and thus it is easy to know how much the eccentricity is caused by what cause. The results here are used as eccentric monitoring information.

Next, as the eccentric synthesis unit 102, as a part for synthesizing the eccentricity again for the eccentric control from the detected eccentricity, mainly, only the fundamental wave and the double wave are synthesized and used for eccentric control, and the thickness controller 106 and the position The controller 107 controls the roll gap and uses the sample and marker pulses generated by the pulse generator to synchronize the phase of the output signal with the phase of the eccentricity.

2 is a flowchart illustrating a process for performing a roll eccentric detection method according to an embodiment of the present invention.

First, in step S201, rolling data and setting data such as a load signal from each mill stand, a pulse generation signal from a pulse generator, a steel plate input signal, a steel plate output signal, and a rolling load signal are collected, and then in step S202, It is determined whether the steel plate input signal and the marker pulse signal generated every roll rotation are input.

As a result of the determination, if it is not input, the process returns to the step S202, and if it is input, in step S203, the rolling load is synchronized with the sample pulse signal and stored in the buffer. At this time, the sample pulse is a pulse generated when the circumference of the backup roll is divided into a plurality of bars. In this embodiment, the sample pulse is divided into 64 equal parts. Also, the marker pulse is a pulse that provides a reference point for the position of the backup roll, and one pulse is generated each time the roll is rotated.                     

In step S204, the rolling load is stored until the roll makes one rotation. That is, the average value of the load signal up to one rotation is calculated. The average load signal is removed from each stored load, and the load change is calculated and stored in the buffer.

Subsequently, in step S205, band pass filtering is performed from the stored rolling load, and in step S206, the roll eccentricity is separated for each frequency from the result of the band pass filtering, and in step S207, the size of the eccentricity for each frequency is eccentrically monitored. Output the detection result to use as information for.

Next, in step S208, the fundamental wave and the double wave are synthesized to form a roll eccentric control signal, and then in step S209, the control signal is sent out to the eccentric control output. Then, in step S210, after the steps to continue the process while moving the window for each roll roll, the operation is terminated when the steel sheet exits the stand.

While the invention has been described above based on the preferred embodiments thereof, these embodiments are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention will be limited by the appended claims, and should be construed as including all such changes, modifications or adjustments.

According to the present invention as described above, since the roll eccentricity can be separated for each frequency to know the magnitude of the eccentricity corresponding to each cause, it is not only possible to provide the operator with what cause the eccentricity occurs. The eccentric control is performed by combining the eccentricity of the fundamental wave and the double wave, and thus the plate thickness variation can be greatly reduced.

Claims (4)

In the method for detecting the roll eccentric component caused by the difference between the rotational center and the geometric center of the roll during the rolling process, A first step of receiving a steel plate input signal and a marker pulse signal generated every roll revolution; Synchronizing the rolling load with the sample pulse signal to store the rolling load value until the roll makes one revolution; A third step of calculating a load change by calculating an average value of the load signal from the rolling load value to one revolution and removing the average load signal from each stored load; Performing band pass filtering from the stored rolling load value, separating roll eccentricity for each frequency from the result of the band pass filtering, and outputting an eccentricity for each frequency; A fifth step of composing a roll eccentric control signal by synthesizing a fundamental wave and a double wave to the eccentric magnitude output value for each frequency, and using this as an eccentric control value; Roll eccentric component detection method of the rolling mill comprising a. The method of claim 1, The sample pulse is a roll eccentric component detection method of a rolling mill, characterized in that the pulse generated when dividing the circumference of the backup roll into a plurality. The method of claim 1, The first to fifth steps are repeated each time the roll is rotated once, and is terminated when the plate for detecting the roll eccentric component exits the stand, the roll eccentric component detection method of the rolling mill. The method of claim 1, And said band pass filtering is performed to keep the center frequency of the filter constant regardless of the rolling speed.

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