JPS5997002A - Shape detector - Google Patents

Abstract

PURPOSE:To enable a better detection of a shape detecting a vibration frequency resonating with a metal material by applying a random vibration to a strip- shaped metal material with a random signal generator as vibrating means. CONSTITUTION:A pink noise of 5-50Hz is generated with a random signal generator 10 and amplified with a power amplifier 11 to be fed to a vibrator 12, which utilizes an AC magnet or the like. Vibration of a strip-shaped metal plate 2 is detected with a displacement detector 13 and converted into an electrical signal with signal processing circuit 14. A complicated waveform is converted into a square wave with a limiter circuit 16 passing a BPF15 and a fundamental wave extracted with an LPF17. As in noway affected by the amplitude component of vibration, this system can detect changes in the frequency as voltage change simply by setting an LPF17 and a shield frequency near the center of the detection frequency beforehand. The output thereof can be translated to steepness as normal shape signal with a shape converter 18 to extract a shape signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a flatness detection method for a strip-shaped metal material, and particularly to a non-contact vibration method.

[Prior art]

Shape detection methods in rolling lines include non-contact methods and contact methods. Among the non-contact methods, there is a magnetostrictive method that detects the internal stress distribution of the plate as a change in magnetic permeability, a method that measures the internal stress distribution from the amplitude and frequency of the self-excited vibration of the plate,
There are also methods that detect amplitude changes by applying pressure, and other methods that utilize light such as laser light. In the magnetostrictive method, changes in magnetic permeability vary depending on the material, so calibration requires a lot of time, and in the amplitude method, there are disadvantages such as variations in the width direction of the plate. In addition, in the optical method, when the rolling tension is large, the shape does not become apparent and the precision decreases. To provide a flatness detection device.

[Summary of the invention]

Generally, the means for detecting the flatness of rolled material during rolling is as follows:
The basic idea is to detect the distribution of internal stress. The conventional method utilizes the fact that a rolled steel plate is attracted by electromagnetic force and the displacement thereof is inversely proportional to internal stress. However, the displacement is sensitive to changes in the gap between the steel plate and the detector, and there are practical problems such as large displacement at the edge of the steel plate and contact between the detector and the steel plate. The inventor of the present invention has shown that FIG. 5 (
As shown in ,lo(b)(C), we conducted various experiments on the relationship between vibration, amplitude, and shape of rolled materials, and discovered that the vibration method has very stable response force characteristics compared to the amplitude method. ,
This is what is used. In this case, the frequency method is
This has been considered in the past, but because it relied on self-excited vibrations, it had the disadvantage that sensitivity would drop significantly if vibrations did not occur. Further, in the combined amplitude method, there is a limit in accuracy unless pressurized suction is performed. The present invention provides, as an excitation means,
This method uses a random signal generator to apply random vibrations to a metal material, and attempts to detect the vibration frequency that resonates with the metal material. In this case, the random signal is 10 to 10
A device with a uniform power spectrum up to about 0 Hz is used. In addition, when detecting the resonant vibration frequency of an excited metal material, the amplitude component contains many noise components other than the shape, so by detecting only the resonant frequency, we were able to invent a good shape detection device. .

The vibration frequency due to internal stress of rolled metal material is a fundamental wave and is approximated by the following equation.

However, f: fundamental vibration frequency, t: length between fulcrums r: linear density g: gravity acceleration σ0 = tensile stress Now, when t = 1 m, 6° = 5 kg 7 mm2, the imaging frequency is approximately 40H2, and it can be seen that the frequency is proportional to the square root of the internal stress and is unrelated to the method of excitation.

[Embodiments of the invention]

A shape detector is usually installed on the exit side of a cold rolling mill. The detection signal is displayed in the shape, guides the rolling operation, and
It is used as an automatic shape control signal. FIG. 1 is a diagram showing an outline of a cold rolling mill.

The strip metal plate 2 is rolled by a rolling mill 1, passes through a deflector roll 4, and is wound onto a take-up reel 5. The shape detector 3 of the present invention is installed between the rolling mill 1 and the deflector roll 4. The band-shaped metal plate 2 and the shape detector 3 are
They are placed about 7 songs apart and parallel to each other as much as possible.

The shape detector 3 measures the shape distribution in the amplitude direction,
Consists of a large number of detection ends. The practical range is usually about 10 to 40 pieces. FIG. 2 is a diagram showing the installed state. Band-shaped metal plate 2. Vi is randomly excited by the vibration device 6. This random signal is 20~100H
The signal source is pink noise with a uniform spectrum over 2. This excitation by random signals is important. For example, when vibration is applied in steps, the spectrum is non-uniform, and the signal at the time of vibration cannot be used as a detection signal, making continuous detection impossible. or,
If it is vibrated with a single frequency, it is meaningless because the band-shaped metal plate will vibrate at the contributing frequency or twice its frequency, which is unrelated to the internal stress. The vibration bag @ may be an electromagnetic attraction force generated by an electromagnetic coil, or may be an upward force generated by air pressure. This means that non-magnetic materials such as aluminum, which cannot be used with electromagnetic force, can also be used. FIG. 3 is a diagram showing the circuit configuration of the present invention. A random signal generator generates pink noise of 5-50 H,z. This random signal is amplified by a power amplifier 11 and sent to a vibrator 12. The vibrator 12 can be easily configured using an AC magnet. Furthermore, when using air pressure, the amount of air is controlled by a servo valve. The vibration of the band-shaped metal plate 2 is detected by a displacement detector 13. A non-contact gap sensor is usually used for this purpose. Therefore, the vibration signal is easily converted into an electrical signal by the signal processing circuit 14. Since the vibration signal includes many frequency components, it is passed through a bandpass filter 15 in order to detect only frequencies that occur within a normal stress range. There are several ways to detect the maximum frequency of the power spectrum, but a limiter method is used as a simple example. The limiter circuit 16 converts the complex waveform into a rectangular wave. The fundamental wave of this rectangular wave is extracted by the next low-pass filter 17.

This method is not affected by the vibration amplitude valve, so it simply
By setting the cutoff frequency of the low-pass filter 7 near the center of the detection frequency, frequency changes can be detected as voltage changes. This output is subjected to steepness conversion using a shape converter 18 as a normal shape signal.

FIG. 4 is a diagram showing the overall configuration of the shape detector. A large number of displacement detectors 13 are converted into DC voltage by the broken line part in FIG. 2'1 is displayed. Figure 6 shows
This is an example of a signal waveform output from a random signal generator. The power spectrum of this signal is shown in FIG. In reality, it is not possible to obtain a completely uniform product, but in practice,
no problem. FIG. 8 is an example of a frequency spectrum of vibration of a band-shaped metal plate. When this signal is passed through a filter circuit as shown in FIG. 3, a spectrum as shown in FIG. 9 is separated. Since the amplitude of this vibration is constant, the shape signal can be extracted by setting the cutoff frequency fc'c using the sophisticated low-pass filter shown in FIG.

Note that 10 in the figure is a random signal generator.

〔Effect of the invention〕

According to the present invention, by combining the vibration excitation device and the detection of the vibration frequency, (1) continuous vibration frequency detection becomes possible.

(2) Not affected by excitation power.

(3) There is little influence from the position of vibration.

(4) The excitation by the air source does not need to have constant power.

(5) It is also possible to vibrate separately at the edge and abdomen.

(6) Since the vibration method is used, there is less contact between the band-shaped metal body and the displacement detector.

There are other effects.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a cold rolling mill, Fig. 2 is a relationship diagram between a shape detector and the rolling mill, Fig. 3 is a circuit block diagram of the present invention, and Fig. 4 is a perspective view of a cold rolling mill.
The figure is a block diagram of the present invention, FIG. 5(a). (b) and (C) are diagrams showing experimental data that led to the present invention, Figures 6 and 7 are characteristic diagrams of the random signal generator, and Figure 8 is a diagram showing the experimental data that led to the present invention.
9 shows a vibration analysis diagram of a metal material, FIG. 9 shows a vibration analysis diagram after filtering, and FIG. 10 shows a characteristic diagram of a low-pass filter. 2... Band-shaped metal plate, 3... Shape detector, 10...
Random signal generator, 12... vibrator, 15... band pass filter, 17... low pass filter. 1st bad 2nd b 3rd 4th concave 5th Co-) Stress Xu9. Maru〃 Beak area 2nd 6th eye early 7th mouth to eye

Claims (1)

[Claims] 1. In a shape detector for a band-shaped metal plate, a random signal generator and an exciter that give random vibrations to the metal plate, and means for detecting vibrations of the band-shaped metal plate using the signals. and,
A shape detection device comprising a filter circuit that extracts only frequency components caused by shape from the vibration signal. 2. A shape detection device according to claim 1, characterized in that an electromagnet is used as the vibrator. 3. A shape detection device according to claim 1, characterized in that air pressure is used as the vibrator.