JPS60181648A - Eddy current flaw detection apparatus - Google Patents

Abstract

PURPOSE:To perform measurement with good accuracy by reducing noise without being affected by the change in the material of an object to be inspected, by detecting a phase while continuously changing the same by a variable phase shifter when impedance change is detected by the measurement of a detection coil. CONSTITUTION:A shaft obtained by welding stainless steel 1a and steel 1b along a welding line 1c is grapsed by a rotary chuck 2 and the welding line 1c is measured by an eddy current flaw detection coil 4 while impedance from the flaw detection coil 4 is detected by an impedance measuring instrument 6. Then, the signal from a rotary signal generator 3 is inputted to a phase shift scanner 7 to control a variable phase meter 64. For example, a phase is shifted by 1 deg. at every one rotation of a shaft so as to reach 360 deg. to perform phase shift scanning, and output Y and output X are detected by phase detectors 66, 67. If there is a flaw at this time, the output Y has no point, where the value comes to zero, over a total phase. Therefore, the min. value of the output Y is detected by continuously changing a phase by the variable phase shifter and compared with a reference value to make it possible to perform flaw detection with good accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to eddy current detection equipment and flaw detection equipment (fitting), and particularly to an eddy current detection equipment that can be applied to automatic engine pulp shaft weld boundary inspection equipment.

For example, iF such as iron and stainless steel with a diameter of 5φ to 15φ
Conventionally, dye penetrant flaw detection has been applied as a method for detecting flaws in the welded area after contacting A-gold powder with a friction bath and grinding the surface of the welded area. Therefore, a method was adopted in which the inspector observed the instructions given by the scratches. However, this method increases costs and reduces efficiency when the number of specimens increases, and it also requires sampling inspection, which may lead to defective products being overlooked and reduce product reliability.
Otherwise, inefficient manual work is involved in the silk reeling line, which has hindered the production line from becoming whiter.

The present invention was proposed in view of the above circumstances, and its purpose is to reduce the influence of changes in the substance of the specimen and the influence of flaw detection noise, and to automate flaw detection. To provide eddy current flaw detection equipment.

An eddy current flaw detection device according to the present invention is an eddy current flaw detection device that performs flaw detection by scanning a specimen with a detection coil held in a coil scanner, and includes an impedance measuring device connected to the detection coil and detecting a change in impedance thereof;
The impedance measuring device includes a phase detector for detecting the phase of the detection signal, a phase shifter for controlling the phase detector, a controller for controlling the coil scanner, and a controller for controlling the coil scanner. It is characterized by comprising a phase scanner that controls a phase shifter to continuously change the phase of the reference beam supplied to the phase detector. By detecting and obtaining a phase scanning output, the influence of changes in the quality of the paulownia specimen and the influence of certain offshore flaw detection noises are reduced, the flaw detection work is automated, and the above-mentioned drawbacks of the conventional method can be overcome. It is something.

An embodiment of the present invention will be described in detail with reference to the attached Figure mI.

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a diagram showing the characteristics of the detection signal in FIG. 1, and FIG. 3 is the output obtained by phase shifting the impedance measuring device shown in FIG. FIG. 4 is a diagram showing the Y output after phase detection of the impedance measuring device of FIG. 1.

In FIG. 1, the shaft is the JFi object,
In the central part, materials such as stainless steel 7a and fMlb are welded, and the bath contact part is ground and made smooth. The weld lines lc are on the same circumference, and breaks in the welds are detected. 2
(shirt) with a rotating chuck) and rotate it continuously.

3 is a rotation signal generator which generates a pulse signal every time the rotary chuck 2 rotates once. 4 is an eddy current flaw detection coil held by a fill scanner 5, placed close to or in close contact with the surface of the shirt J, and scanned by the coil scanner 5 at right angles to the weld #IC of the shaft 1. The detection coil 4 is connected to an impedance measuring device 6. The impedance measuring device 6 includes an oscillator 67, a bridge circuit 62. Amplifier 63. Variable phase shifter 64. ．． Consisting of a 90° fixed phase shifter 659 and phase detectors 66' and 67, the detection coil 4
07 is a signal phase scanner which separates the impedance change into a resistance component and a reactance component and obtains a DC voltage signal proportional to each component.
1 to control and phase the variable phase shifter 64 by the signal 08
The welding line detector detects the welding line lc and at the same time sends a stop signal to the coil scanner 5 to stop it. 9 is a sardine low value detector.

A signal comparator 10 compares the signal detected by the lowest value detector 9 with a standard signal voltage set by a signal comparator 10, and generates a signal when the voltage is higher than the standard signal voltage.

The controller 1 includes a coil scanner 5, a phase scanner 7.
Welding M! The detector 8 and the minimum value detector 9 are each controlled based on external commands.

The operation of the above-mentioned embodiment of the present invention will be explained. On the Kinio side, the detection coil 4 is fixed in advance to a sound welded part, and the bridge circuit 62 and the amplifier 6 are
3 and variable phase shifter 64 to adjust each phase detector 66 .
It is assumed that the outputs X and Y of 67 are adjusted to zero, and this state is used as a reference point. Further, assuming that there is a flaw in the weld in this state, when the outputs X and Y are observed on an X and Y oscilloscope, trajectories such as those shown in FIGS. 2(A) to 2(E) will be obtained. In other words, when there is no scratch on the shaft J, the signal will be a linear trajectory as the shaft 71-7 rotates, but if there is any abnormality on the shaft J, the signal will be (c), ni), (e). The trajectory will be like this. Moreover, when the detection coil 4 crosses the welding line Jc, the trajectory passes through <X=O as shown in (E).

The point where X=0 is the position where the detection coil 4 faces the welding line Jc. Note that the trajectory shown in Figure 2 is (a). (b) shows the trajectory numbers when the shaft 1 is healthy, (c) shows the case where the shaft 1 has a small scratch, (b) shows the case where there is a rather large flaw, and (e) shows the trajectory number when there is a large flaw.

Here, first, the shaft l is attached to the rotary chuck 2 and rotated continuously. Next, an external command is given to the controller 11 to move the coil scanner 5 and scan the detection coil 4 in the direction of A→C (or C→A) in FIG. At this time, the output signal of the impedance measuring device 6 is as shown in the example shown in FIG. Trace, X-←).

Draw a locus in the area of Y = (→). In this process, when X = 0, this is detected by the acid contact detector 8, and this signal is input to the controller 1). No. 1 thereby stops the coil scanner 5. As a result, the detection coil 4 continuously scans the weld 11J)c, and the signals shown in FIGS. 2A to 2E are outputted from the impedance measuring device 6. Next, an external command signal is given to the controller 11 to operate the phase scanner 7. The phase scanner 7 receives the signal from the rotation signal generator 3 and controls the variable phase shifter 64 so as to shift the phase by, for example, 1° every rotation of the shaft 1, and stops its function when the phase has shifted 360°. . In this process, the output of the impedance measuring device 6 rotates as shown in FIG.
The output changes as shown in FIG. 4, for example. That is, in the case of a healthy welded part with no flaws, there is a point where the output Y becomes zero, and in the case of some kind of abnormality, there is no point where the output Y becomes zero. The phase shifter is θ.

Output Y while changing to ~360° and undergoing phase scanning
is measured by the minimum value detector 9, and when the scanning is finished,
The minimum value detector 9Fi outputs a voltage proportional to the output Y, and is input to the signal comparator 0. This signal comparator No. 0 has a reference voltage source that can be set arbitrarily, and the reference voltage is used to detect the lowest value when there is no flaw on the test object or when the flaw is small enough to be acceptable. The voltage output to the device 9 is set to about 1.

Therefore, a signal larger than this reference voltage
Since the signal comparator 10 produces a constant output when the signal is input to the signal comparator 10, the presence or absence of compensation can be determined by whether or not the signal comparator 10 has a constant output.

Furthermore, by performing phase scanning as shown in the example of Fig. 4,
(A) in Fig. 2 due to minute changes in the Kiribi of shaft 1,
Even if the erection shown in (b) has a slight bulge, or even if the trajectory is compatible with that shown by the dotted line in (b) in Figure 2, the detectability of the foot i11: can be improved. For example, if the material of the shirt tonneau is iron-stainless (5
LIS304) Iron-stainless steel (SUS321), etc., can be tested easily! It changes depending on the IC. However, the effect of lowering the h4 value of the tangible output due to the unpleasantness of φl is the same, and there is no difference in the flaw detection function.

As described above, according to the present invention, a moving body resembling a weight can be produced.

(1) Compared to dye penetrant flaw detection, which has been conventionally applied as a flaw detection method for this type of parts, inspection It is possible to make people into hobbyists.

(2) Inspection of the subject using the same detection coil
The device can detect the position of the connection part of the paulownia wood and the presence of flaws in the penetrating part. It is possible to eliminate the influence of the phase change in the flaw detection output caused by an increase in the phase η of the test object, and therefore the same device can be applied to test objects of questionable quality. ) By detecting the minimum value of phase scanning and flaw detection output, it is possible to detect the effects of signals (for example, noise such as the signal in Figure 2 (c)) caused by changes in the gap between the detection coil and the surface of the test object.・It is possible to detect scratches without receiving damage.

1.1 Explanation of the knots on the first page of the sheet Figure 1 is a diagram showing the configuration of an embodiment of the present invention, Figure 2 is a diagram showing the characteristics of the detected key signature in Figure 1, and Figure 3 is a diagram showing the characteristics of the key signature detected in Figure 1. FIG. 4 is a diagram showing the output obtained by the phase shift of the impedance measuring device shown in FIG. 1, and FIG. 4 is a diagram showing the Y output after phase scanning of the impedance measuring device shown in FIG.

J... Shaft (subject), 3... Rotation signal generator, 4... Detection coil, 5... Coil scanner, 6...
... Impedance measuring device, 7... Mon phase scanner, Horn... Controller, 64... Tsubasa displacement A11 device, 66, 67... April detection hot soup.

Claims (1)

[Claims] In a whirlpool bee/wound device that detects flaws by scanning the object with a detection coil held in a coil scanner, an impintance measuring device that is connected to the detection coil and detects impedance changes. , a phase detector installed in this impedance measuring device to detect the phase of detection I, a variable phase shifter to control this phase detector, a controller to control the front z[i coil scanner, and this controller. and controls the E, l phase shifter to
Part I to provide to the 1ll position detector! An eddy current exploration device characterized by being equipped with a phase scanner that continuously changes the phase of the evening sun.