JPS6288907A - Flatness detector - Google Patents

Abstract

PURPOSE:To detect only shape inferiority with high accuracy by providing a low-pass filter and a minimum value detector and moreover, providing an automatically averaging processing circuit to check a dispersed value (error) or a distance measurement signal under the prescribed quantity. CONSTITUTION:A flatness detector is provided with the low-pass filter 5 which cuts a high-frequency component of a distance signal of a belt-shaped body outputted from a distance measuring instrument and the automatically averaging processing circuit which operates the average number of processing times required based on a S/N ratio from the distance measuring instrument and performs the averaging processing of the distance signal. Then, the distance signal is passed through the low-pass filter in order to eliminate a vibration of the moving belt-shaped body. On the other hand, since the error is not fixed but the S/N varies according to an inclination of the belt-shaped body or the surface shape and a surface state, the S/N of the distance measurement is detected and the S/N vs. The dispersed value (error) stored in the automatically averaging processing circuit 8 is estimated. Then, the average number of processing times required at that time is automatically decided and the averaging is performed for the number of times and the distance signal is processed so as to be under the prescribed dispersed value.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention measures the flatness of a Jfi-shaped body by measuring the displacement of a moving strip at multiple locations in the width direction of the strip. The present invention relates to a flatness detection device for detecting flatness.

[Conventional technology]

On a hot rolling line, defects in the shape of the rolled object, i.e., the strip, such as elongation or ear waves, become apparent, and it is necessary to directly measure the displacement or inclination of the strip at multiple locations in the width direction of the strip. It is well known that it is possible to detect the flatness of a strip by this method.

FIG. 3 shows a general example of a flatness detection device that detects the flatness of a strip by measuring the displacement of the strip at a plurality of locations in the width direction of the strip.

In FIG. 3, (1) is the object to be measured, that is, a strip, (
IA) is a distance signal of the strip, and (2) is a distance measuring device that measures the distance from the distance gaiWl device to the strip. A plurality of distance measuring devices are installed in the width direction on the strip at predetermined intervals from the strip. (3) is an arc length calculator that produces the arc length of the distance signal of the strip output from the distance measuring device, and (4) is an elongation that calculates the ratio of the arc length calculated by the arc length calculator to the straight line. It is a rate calculator.

Next, the operation will be explained.

As shown in Fig. 4, the distance from the distance gl measuring device to the strip at time t! y, and the distance glY1+I from the distance measuring device to the belt at time 1Δt, the displacement of the belt is ΔY.
, is calculated as follows.

ΔY+ -Y+ Yl+r ・(1) Also, since the strip moves at a speed υ between the clock and the time 10 ΔL, the moving distance Δx1 of the strip is △X, = υ・△
It is expressed as t −121. Length △Sl of the band-like body moved from time t to time 10△t
From equations (1) and (2), ΔS, = Foka Tr2-4: -'(-A y Ding-'*',,, (obtained in 31, and further moved from point 0 to point n From equation (3), the length S of the strip-like body obtained is S=!=-Σ (ΔS,)
−44).

On the other hand, assuming that the flat strip moves from point 0 to point n, the length of the moved strip is equal to the distance traveled by the strip, and the length l of the moved flat strip is j = ( n−1)·ΔX l −[51. Therefore, the elongation rate β of the strip based on the length l of the moved flat strip can be obtained from equations (4) and (5) as follows.

By the above-described procedure, the elongation rate β can be determined at a plurality of locations on the strip width. The magnitude of this elongation rate β represents the magnitude of the shape defect.

[Problem that the invention seeks to solve]

Conventional flatness detection devices are configured as described above, so fluctuations due to vibration and waviness of the strip (which are converted into an apparent arc length) detect a value larger than the actual shape defect of the strip. In addition, the disadvantage is that it is greatly affected by the vibration and waviness of the strip, and the measurement error of the distance measuring device causes an error in the length of the strip, reducing the accuracy of the elongation rate β. There was a drawback.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it eliminates fluctuations due to vibration and waviness of the strip by adding a low-pass filter and a minimum value detector, and further improves the distance measuring device. Detects the S/N ratio, automatically calculates the required number of averaging processes based on it, and averages the distance measurement values so that the dispersion value (error) of the distance gt signal is below the specified value. By processing, the accuracy of the distance gl measurement value is ensured, and a flatness detection device capable of detecting highly accurate flatness is provided.

[Means for solving problems]

Arc length errors due to vibration and waviness of the strip are smoothed by a low-pass filter, and distance measurement errors are
The average processing is executed by recognizing the number of times of averaging processing.

[For production]

The low-pass filter in the invention of B smoothes the high-frequency components of the distance signal caused by the vibration and waviness of the band-shaped body to reduce the arc length error, and also arbitrarily averages the distance measurement values to improve the accuracy of the distance S measurement by -L. to reduce the arc length error. This enables more accurate flatness measurement.

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (11 is the object to be measured, that is, a strip, (1) is the distance signal of the strip, and (2) is a distance gl measuring device that measures the distance from the distance measuring device to the strip. Multiple units are installed in the width direction on the strip.(5
) is a low-pass filter that cuts the high-frequency component in the distance signal of the band-shaped object output from the distance S measurement unit, and (3) calculates the arc length of the output signal of the low-pass filter that cuts the high-frequency component of the distance signal of the band-shaped object. (6) is a minimum value detector that detects the minimum value of the arc length signals of multiple arc length calculators; (7) is a minimum value detector that detects the arc length signals from the arc length calculators and the minimum value. This is a relative elongation rate calculator that calculates the relative elongation rate from the output signal of the device. (8) is an automatic averaging processing circuit that calculates the required number of averaging processing based on the S/N ratio from the distance gI measuring device and executes averaging processing of the distance signal.

Next, the operation of the present invention will be explained. As mentioned above, the displacement △Y of the belt-shaped body is calculated at time t2 according to equation (1).
Distance giY from the measuring device to the strip at +8
I, Y Big measurement 1: ``A running difference occurs.''

In the present invention, the distance signal is passed through a low-pass filter in order to remove vibrations of the moving band. An example of low-pass filter processing is given below.

Distance No. 43 YI when time 2 is 10Δt.

The value of Y, , after passing through the low-pass filter is Y, ,
Assuming Y+++, find as follows. Therefore, ΔY1 of the strip is ΔY +
= Y + Y +++ -191. Further, in the same manner as in the prior art, the length ΔS■ of the strip moved from time t to time t''Δt and the length S of the strip moved from point 0 to point I-n are as follows. required.

△S, = △, + △Yl' (10) According to the above procedure, the length S of the band-shaped body that has been moved at a plurality of positions of the width of the plate on the band-shaped body is determined.

Length S of the strip obtained at multiple points of the board width on the strip
The minimum side L≧ is the measurement point that is closest to flatness. Therefore, this minimum value S1. , relative elongation rate β
′, we get . Since the waviness of the strip is a common variation at multiple locations on the strip, the common variation B can be removed by using the minimum value S + mln as a reference.

Further, the maximum value S, □ of the length S of the strip-shaped body determined at a plurality of locations on the width of the strip is the location where the shape defect is the largest among the measurement locations. Therefore, when the relative elongation rate β'' is calculated using this maximum value S may as a reference, it becomes β″=i=iTEL). Similarly to β', the relative elongation rate β' can be used to eliminate waviness of the band, which is a common variation at multiple locations on the band.

In addition, j = − ~ found at multiple locations of the board width on the strip
-(141) The relative elongation rate β can be used in the same way as β' to remove the waviness of the strip, which is a common fluctuation at multiple locations on the strip.

However, the dispersion value (error) of the distance signal from the distance measuring device
Generally, the dispersion value (error) is not constant and varies due to the S/N ratio varying depending on the inclination of the strip or the surface shape 2 surface condition. The automatic averaging processing circuit (8) works effectively against such phenomena. That is, the S/N of the distance S measurement is detected and stored in advance in the automatic averaging processing circuit (8). From the S/N vs. variance value (error) data, the variance value (
error). Similarly, it is stored in the automatic averaging processing circuit (8). By referring to the relational expression or table of the variance value (error) versus the number of averaging processes, the number of averaging processes required at that time is automatically determined, the distance signal is averaged that number of times, and the specified variance value is determined. Process the distance signal so that it is below (error) and send it to the next stage low-pass filter.

〔Effect of the invention〕

As described above, according to the invention of Party B, a low-pass filter and a minimum value detector are added in order to remove vibrations and waviness of the band-shaped body, and the dispersion value (error) of the distance am constant signal is kept below a specified amount. Since an automatic averaging processing circuit has been added to suppress the vibration and waviness of the strip, it is not affected by the influence of the error fluctuation of the distance gI measurement value, or the influence of the error amount exceeding the tolerance, and only the shape defects are enhanced. This has the effect of providing a flatness detection device that detects with high accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a flatness detection device according to an embodiment of the present invention, FIG. 4 is a diagram showing a strip and its distance signal, and FIG.
The figure is a block diagram of a conventional flatness detection device, and the second figure is the distance g.
l? Jt! FIG. 3 is a diagram showing a distance signal between an l-determiner and a band-shaped body. In the figure, (1) is the object to be measured, (IAI is the distance signal of the object to be measured, (2) is the distance at measuring device, (3) is the arc length calculator,
(4) is an elongation rate calculator, (5) is a low-pass filter, (
6LI is the minimum value detector, (7) is the relative elongation rate calculator, (
8) is an automatic averaging processing circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (3)

[Claims] (1) Multiple distance measuring devices that measure the distance from the distance measuring device to the strip, and the amount of dispersion of the distance signal by detecting the S/N ratio of the distance signals measured by the multiple distance measuring devices. An automatic averaging processing circuit that judges the amount of variance (error amount) and performs the necessary averaging processing so that it is less than the specified amount of variance (error amount), multiple low-pass filters that cut high frequencies of the distance signal, and low-pass A plurality of arc length calculators that calculate the arc length of the distance signal whose high frequency components have been cut by the filter, and a minimum value detector that detects the minimum value of the arc length signal calculated by the plurality of arc length calculators. flatness detection characterized by comprising an arc length signal obtained from a plurality of arc length calculators and a relative elongation rate calculator that calculates a relative elongation rate from the minimum value signal of the arc length signals. Device. (2) Detect the minimum value of the arc length signal calculated by multiple arc length calculators Instead of the minimum value detector, detect the maximum value of the arc length signals calculated by multiple arc length calculators. 2. The flatness detection device according to claim 1, further comprising a maximum value detector. (3) Instead of a minimum value detector that detects the minimum value of the arc length signals calculated by multiple arc length calculators, the average value of the arc length signals calculated by multiple arc length calculators is detected. 2. The flatness detecting device according to claim 1, further comprising an average value detector.