JPS61178608A - Flatness detector - Google Patents

Abstract

PURPOSE:To obtain an apparatus of higher standard of accuracy, to furnish the apparatus with a plurality of low-path filter for cutting high-frequency of a distance signal, arc-length calculating set for the arc-length of the distance signal and the least-value detecting set for the least value of arc-length signal. CONSTITUTION:A flatness detector is provided with a plurality of low-path filters 5 for cutting high-frequency wave of distance signal measured by a plurality of distance measuring sets, a plurality of arc-length calculating sets 3 for calculating arc-length of the signal from this filters 5, the least value detecting set 6 detecting the least value of output from the arc-length calculating sets 3, and relative elongation ratio calculating set calculating the relative elongation ratio from arc-length signal of each channel and the least value signal of the arc-length signal. In this case, in order to remove vibration and wavy motion of a ribbon material, as low-path filter and least value detecting set are added, detection can be limited only to detective shapes and accordingly, accuracy can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flatness detection device that detects the flatness of a moving strip by measuring the displacement of the strip at a plurality of locations in the width direction of the strip.

[Conventional technology]

In the M rolling line, shape defects such as elongation and ear waves in the rolled object, i.e., the strip, have become apparent, so 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

FIG. 1 shows a general example of flatness detection IT 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. 1, (1) represents the object to be measured, that is, the strip 1 (
IA) is a distance signal of the strip, and (2) is a distance measuring device for measuring the distance from the distance measuring device to the strip. A plurality of distance measuring devices are installed in the width direction on the strip at a predetermined interval from the strip.

(3) is an arc length calculator that calculates the arc length of the distance signal of the strip output from the distance measuring device, and (4) is an elongation calculator 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. 2, the displacement Δy of one strip is determined by the distance yI from the distance measuring device to the strip at time t and the distance Y I+1 from the distance measuring device to the strip at time t+Δt.
i is calculated as follows.

Δy+=y+ y++1...(1)
Also, since the strip moves at a speed V between time t and time t+Δt, the moving distance of the strip is Δχ1, so Δxl=y'
Δt is expressed as (2). The length Δ8i of the band-shaped body moved between time t and time t+Δt is calculated from equations (1) and (2) as follows: Δ13i=
π20 "b; Darkness Y...1 obtained by (3), and
Length S of the strip moved from point 0 to point n
is obtained from equation (3).

On the other hand, assuming that the flat strip moves from point 0 to Dintro, the length of the moved strip is equal to the distance the strip moved, and the length l of the moved flat strip is J = (n- 1) φΔXi ... is expressed as (5). 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).

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]

Since the conventional flatness detection device is configured as described above, fluctuations due to vibration and waviness of the strip are converted into an apparent upper arc length, and a value larger than the actual shape defect of the strip is detected. There was a drawback that it could be stored away. Furthermore, there is a drawback that it is greatly affected by vibrations and waviness of the band-shaped body.

This invention was made in order to eliminate the drawbacks of the conventional devices as described above, and aims to provide a flatness detection device that can detect flatness with high accuracy by eliminating fluctuations due to vibration and waviness of a band-shaped body. This is the purpose.

[Means for solving problems]

The flatness detection device of the present invention includes a plurality of low-pass filters that cut out high frequencies of distance signals measured by a plurality of distance measuring devices, and a plurality of arc filters that calculate the arc length of the signal from the low-pass filters. A length calculator, a minimum value detector that detects the minimum value of the output from this arc length calculator, and a relative elongation rate that calculates the relative elongation rate from the arc length signal of each channel and the minimum value signal of the arc length signal. It is equipped with a computing unit.

[Effect]

In the present invention, fluctuations due to vibration and waviness of the band-shaped body are removed using a low-pass filter and a minimum value detector, and flatness is detected with high accuracy.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 8th
In the figure, (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 for measuring the distance from the distance measuring device to the strip. A plurality of distance measuring devices are installed in the width direction on the strip at a predetermined interval from the strip. (I
s) is a low-pass filter that cuts the high frequency of the distance signal of the belt-shaped object output from the distance measuring device, and (3) calculates the arc length of the output signal of the low-pass filter that cuts the high frequency of the distance signal of the belt-shaped object. an arc length calculator; (6) is a minimum value detector that detects the minimum value of the arc length signals of a plurality of arc length calculators;
(7) is a relative elongation rate calculator that calculates a relative elongation rate from the arc length signal from the arc length calculator and the output signal of the minimum value detector.

Next, the operation of the present invention will be explained.

As mentioned above, the displacement Δy1 of the band-shaped body is determined by the difference between the distance Yi+yi+1 from the distance measuring device to the band-shaped body at time t1 and time t+Δt using equation (1), but in reality, the displacement Δy1 of the band-shaped body is It vibrates, and as shown in Figure 4, the band-shaped body (
A large measurement error occurs between 1) and the distance signal (IA) of the strip.

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 signal yI, yi+1 at time t99 time +Δt
Let the value after passing through the low-pass filter be 51...
...... (7) ...... (8) Calculate as follows. Therefore, the displacement Δ distance of the strip is Δ)'i
=yt −Yi+1 °°(9
). Furthermore, in the same manner as in the prior art, time t
The length ΔSi of the belt-shaped body moved from time t+Δt to time t+Δt, and the length S of the belt-shaped body moved from India 0 to point n are determined as follows.

x8i = (xxl 3" + (ayi)"
-Q.

Through the above-described procedure, the length 8 of the moved strip is determined at a plurality of locations along the width of the strip.

Length S of the strip obtained at multiple points of the board width on the strip
The minimum value of 8m1n is the closest to flatness among the measurement points. Therefore, when the relative elongation rate β' is calculated using this minimum value of 8 mIn as a reference, it becomes as follows. Since the waviness of the strip is a common variation at multiple locations on the strip, this common variation can be removed by using the minimum value of 8m1n as a standard. The maximum value Brnax of the length S of the strip-like body determined by is the location where the shape defect is the largest among the measurement locations. Therefore, if we calculate the relative elongation rate β'' using this maximum value Brn*x as a reference, it becomes as follows.The relative elongation rate β'' is the same as β', and the relative elongation rate β'' is a common fluctuation at multiple locations on the band-shaped body. Waviness can be removed.

Moreover, when the relative elongation rate β is determined based on the average value Sm of the length S of the strip-shaped body determined at a plurality of locations of the board width on the strip-shaped body, the following is obtained. Similarly to l, the relative elongation rate β can eliminate the waviness of the strip, which is a common variation at multiple locations on the strip.

〔Effect of the invention〕

As described above, according to the present invention, in order to remove the vibrations and waviness of the band-shaped body, a low bar number and a minimum value detector are added, so that only shape defects can be detected without being affected by the vibrations and waviness of the band-shaped body. This has the effect of providing a highly accurate flatness detection device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a flatness detection device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing a strip and its distance signal,
FIG. 8 is a block diagram of a conventional flatness detection device, and FIG. 4 is an explanatory diagram showing a distance measuring device and a distance signal of a strip. In the figure, (1) is the object to be measured, (IA) is the distance signal of the object to be measured, (2) is the distance measuring device, (3) is the arc length calculator, (
4) is an elongation rate calculator, (5) is a low-pass filter, (6
) is the minimum value detector, and (7) is the relative elongation rate calculator. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (3)

[Claims] (1) A plurality of distance measuring devices that measure the distance from the distance measuring device to the strip, and a plurality of low-pass filters that cut high frequencies of distance signals measured by the plurality of distance measuring devices; Multiple arc length calculators calculate the arc length of the distance signal whose high frequency components have been cut by a low-pass filter, and detect the minimum value of the arc length signal calculated by the multiple arc length calculators. A flatness detection device comprising: a minimum value detector; and a relative elongation rate calculator that calculates a relative elongation rate from the arc length signal of each channel and the minimum value signal of the arc length signal. (2) The maximum value of the arc length signal calculated by multiple arc length calculators instead of the minimum value detector that detects the minimum 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 for detecting a value. (3) Instead of a minimum value detector that detects the minimum value of the arc length signal calculated by multiple arc length calculation units, the minimum value detector detects the minimum value of the arc length signal calculated by multiple arc length calculation units. 2. The flatness detection device according to claim 1, further comprising an average value detector for detecting an average value.