JP3132263B2 - Abnormality judgment method of crystal grain measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band-shaped test material in which normal grains having uniform crystal orientations and abnormal grains having non-uniform crystal orientations are mixed and transmitted / received while scanning an ultrasonic wave. The difference in the ultrasonic wave propagation velocity due to the crystal orientation is converted into the difference in the amplitude using the resonance phenomenon due to the multiple reflection interference in the test material. The present invention relates to a method for judging abnormalities of a crystal grain measuring device for detecting abnormal grains, and particularly to detect abnormalities of a crystal grain measuring device at an early stage, which is suitable for use in detecting an abnormal grain direction of a grain-oriented silicon steel sheet. The present invention relates to a simple abnormality determination method.

[0002]

2. Description of the Related Art Oriented silicon steel sheets having excellent electromagnetic characteristics in a rolling direction have been manufactured for the purpose of applying an alternating current to a core of a step-up transformer or the like. In the grain-oriented silicon steel sheet, the secondary recrystallization orientation in the rolling direction is set to <100> (Goss orientation) to greatly improve magnetism.

As the number of crystal grains close to the Goss orientation increases,
Although it becomes a oriented silicon steel sheet with excellent electromagnetic characteristics,
In an actual manufacturing process, it is not always possible to produce only a crystal grain close to the Goss orientation. If the secondary recrystallization is insufficient due to a change in manufacturing conditions or disturbance, a crystal grain greatly deviating from the Goss orientation, a so-called abnormal state, Grains are formed,
The magnetic properties are deteriorated and the quality is rejected.

FIG. 1 is a schematic diagram of a product steel sheet 10 having the abnormal grains 10A. Normal grain 10B close to Goss orientation
Although the grain size is as large as several mm to several tens of mm, in the abnormal grain 10A, the grain size is generally several mm or less, and the orientation of the crystal grains is random, and as shown in FIG. It is elongated and distributed.

As a device for detecting such abnormal grains in a grain-oriented silicon steel sheet, the applicant has already disclosed Japanese Patent Application Laid-Open No. 1-222962.
The difference in the ultrasonic wave propagation velocity between the normal grain and the abnormal grain is converted into a difference in amplitude using the resonance phenomenon caused by multiple reflection interference in the steel sheet. There has been proposed an apparatus for measuring a grain orientation distribution of a grain-oriented silicon steel sheet in which grains are detected.

As shown in FIG. 2, the principle of the transmission type is shown in FIG. 2. The elasticity coefficient differs depending on the crystal orientation, and the ultrasonic propagation speed in the thickness direction differs between normal grains and abnormal grains. Then, the difference in propagation speed is converted into the difference in amplitude, and abnormal grains are determined from the amount of signal attenuation. That is, in the case of a normal grain, since the ultrasonic wave resonates under the resonance condition 2d = λ (d is the plate thickness, λ is the wavelength of the ultrasonic wave), as shown in FIG. 2B, ultrasonic waves having a large amplitude are incident on the ultrasonic probe 22B. On the other hand, in a portion where abnormal grains are present, as shown in FIG. Since the amplitude decreases, abnormal grains are detected using this difference. In FIG. 2, reference numeral 22A denotes an ultrasonic probe on the transmission side.

This measuring device is configured as shown in FIG. 3 as an example of a reflection type, in which, for example, a burst wave-like electric signal generated by an ultrasonic transmission circuit 20 is opposed to a steel plate 10 to be measured. Reflection type ultrasonic probe 2 arranged
2 is supplied. The ultrasonic probe 22 is scanned, for example, in the width direction of the steel plate 10 by the scanning device 26, and the ultrasonic probe 22 makes the ultrasonic wave incident on the steel plate 10 while scanning. The ultrasonic wave reflected by the bottom surface of the steel plate 10 and modulated according to the crystal orientation of each crystal in the steel plate 10 is received again by the ultrasonic probe 22 and input to the ultrasonic receiving circuit 28. The received signal amplified by the ultrasonic receiving circuit 28 is input to the gate circuit 30. Gate circuit 3
By means of 0, only the part of the received signal that well represents the signal modulated according to the crystal orientation is extracted and input to the peak hold circuit 32. Peak hold circuit 32
Detects and holds the peak value of the signal from the gate circuit 30 during one repetition period until the next pulse comes. The output of the peak hold circuit 32 is converted into a digital signal by an A / D converter 34,
6 is input. The microprocessor 36 receives the digital signal from the A / D converter 34 and the probe position signal from the scanning device 26, and determines abnormal grains and normal grains based on the magnitude of the received signal. Output to the display device 38.

In FIG. 3, reference numeral 40 denotes the scanning device 26.
Is a timing control circuit that outputs repetitive pulses at a rate of, for example, 1 to 10 kHz according to the probe scanning speed.

Japanese Patent Application Laid-Open No. 51-29187 also discloses a crystal grain size determination method for determining the size of crystal grains of a silicon steel sheet by ultrasonic waves.

[0010] According to such a crystal grain measuring apparatus, it is possible to perform non-destructive online measurement of abnormal grains of a silicon steel sheet.

[0011]

However, conventionally, no method has been devised to detect an abnormality in the crystal grain measuring device at an early stage, and there have been cases where the discovery of an abnormality in the crystal grain measuring device is delayed. In particular, failure of the ultrasonic transmission circuit 20 and the reception circuit 28 placed in a bad atmosphere such as sulfide corrosive gas,
An abnormality determination method that can be quickly found has been desired.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method for judging an abnormality of a crystal grain measuring device which can detect an abnormality of the crystal grain measuring device at an early stage.

[0013]

SUMMARY OF THE INVENTION According to the present invention, a strip-shaped test material in which normal grains having a uniform crystal orientation and abnormal grains having a non-uniform crystal orientation are mixed is transmitted and received while scanning an ultrasonic wave. The difference in ultrasonic wave propagation speed due to the crystal orientation of the crystal is converted into a difference in amplitude using the resonance phenomenon caused by multiple reflection interference in the test material. In the crystal grain measuring device that detects abnormal grains in the data, a predetermined number of data having a large amplitude is extracted from the data obtained in one scan, and an average value thereof is obtained, and when the average value is out of the predetermined range, By determining that the crystal grain measuring device is abnormal,
The above object has been achieved.

Further, the predetermined range is a value corresponding to a reference amplitude of a normal grain.

[0015]

[Function] Even if the steel sheet to be measured has an abnormal grain on the entire surface, since there is always a crystal grain having the same crystal orientation as a normal grain, for example, data scanned in the width direction always resonates and is the same as a normal grain. Some data indicating the amplitude are included. Therefore,
If data is collected from data having a higher amplitude from data obtained in one scan, and the amplitude is compared with the reference amplitude of a normal grain, abnormality of the measurement circuit can be determined at an early stage.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

For example, the detection of the plate edge and the determination of the abnormal grain in this embodiment, which are carried out by using an apparatus as shown in FIG.
This is performed according to a procedure as shown in FIG.

That is, the average voltage level of normal grains is V
b (7V) (Step 10
0).

Next, in step 102, as shown in FIG. 5, for each of the scans L1 to L7, the voltage data of the output of the ultrasonic receiving circuit 28 is sampled at a pitch of, for example, 1 mm in the width direction, and as shown in FIG. The measurement data of the Lth scan is obtained.

Next, the routine proceeds to step 104, where a range of the plate edge level Va (for example, 9 V) or less is determined from the voltage data of one scan, and this range is defined as the range of the plate. The range where the voltage level V exceeds the plate edge level Va is a portion where there is no plate, and is excluded from data processing (step 1).
06).

In step 110, the voltage data in the plate range for which the determination result in step 104 is positive is compared with an abnormal grain determination level Vc (for example, 4 V), and a portion below Vc is determined as an abnormal grain (step 112). ). Similarly, in the voltage data within the plate range, a portion exceeding the abnormal grain determination level Vc is determined to be a normal grain (step 114).

On the other hand, the abnormality determination of the measuring circuit according to the present invention is performed according to the procedure as shown in FIG.

With respect to the voltage data in the range of the plate extracted in step 104 of FIG. 4 described above, the maximum of the voltage is set for each channel (in the embodiment, two channels of the first channel on the left and the second channel on the right). N values (3 in the example)
Sampled) voltage data. In the example of FIG.
Each of data V11, V12, V13 of the first channel and data V21, V22, V23 of the second channel.
Are sampled. The data is sampled, for example, by scanning n times after a predetermined distance Lm from the head of the steel plate 10.

Next, an average value of N pieces of voltage data is obtained for each channel (step 202).

Next, the process proceeds to step 204, where it is determined whether or not the calculated average value is within the reference voltage (Vb) ± a% (for example, 5%) of normal grains (step 20).
4). If the determination result is positive, it is determined that it is normal (step 206). On the other hand, if the result of the determination in step 204 is negative, it is determined that the transmission / reception circuit and probe of the corresponding channel are abnormal, such as deterioration and drift (step 208).

The above determination is performed for each steel plate and each flaw detection channel to determine whether the measurement circuit is abnormal.

In the apparatus shown in FIG. 3, the ultrasonic waves reflected by the steel sheet are detected. However, a pair of probes are provided above and below the steel sheet 10 so that the ultrasonic waves passing through the steel sheet can be detected. It is clear that the present invention can be similarly applied to a transmission type crystal grain measuring device for detection.

[0028]

As described above, the present invention has an excellent effect that abnormalities such as deterioration and drift of a transmitting / receiving circuit and a probe can be detected at an early stage.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a silicon steel sheet containing abnormal grains, which is an example of a measurement target of the present invention.

FIG. 2 is a cross-sectional view showing the principle of measuring crystal grains.

FIG. 3 is a block diagram including a partial perspective view showing a basic configuration example of a crystal grain measuring device.

FIG. 4 is a flowchart showing a procedure for detecting a plate edge and determining an abnormal grain in the embodiment of the crystal grain measuring apparatus.

FIG. 5 is a perspective view showing an example of a scanning path of a measurement target.

FIG. 6 is a diagram showing an example of data obtained by one scan.

FIG. 7 is a flowchart showing a procedure of abnormality determination according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Steel plate 20 ... Ultrasonic transmission circuit 22, 22A, 22B ... Ultrasonic probe 26 ... Scanning device 28 ... Ultrasonic reception circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 29/00-29/28

Claims (2)

(57) [Claims] An ultrasonic wave is transmitted and received while scanning an ultrasonic wave to and from a band-shaped test material in which normal grains having uniform crystal orientations and abnormal grains having a non-uniform crystal orientation are mixed. A crystal that converts the speed difference into an amplitude difference using the resonance phenomenon caused by multiple reflection interference in the test material, and detects abnormal grains in the test material from the amplitude attenuation when abnormal grains occur. In the grain measuring device, a predetermined number of data having a large amplitude is extracted from the data obtained in one scan, and the average value is obtained. When the average value is out of the predetermined range, it is determined that the crystal grain measuring device is abnormal. A method for determining an abnormality of a crystal grain measuring device, wherein the determination is performed. 2. A method according to claim 1, wherein said predetermined range is a value corresponding to a reference amplitude of a normal grain.