JPH02130462A - Eddy current test probe - Google Patents

Abstract

PURPOSE:To enable detection of both of a minute flaw and a flaw in the longitudinal direction by disposing a plurality of coils on the circumference of one probe and by disposing the coils on a soft material. CONSTITUTION:Coils 7 to 10 are not divided to be equal completely on the circumference, but are so sized that the end parts thereof overlap a little each other when they are disposed on the circumference of one probe 1. Besides, the coils 7 to 10 are so fitted as to cover the outer periphery of a soft material 11, such as urethane, having elasticity. Signals from the coils 7 to 10 at the time of flaw detection are so processed that the signals from the coils 7 and 8, and 9 and 10, facing each other respectively are processed as coupled. The signal detected from the coil 7 and that detected from the coil 8 are so processed that the difference between them is detected. According to this constitution, a minute flaw and a flaw in the longitudinal direction can be detected simultaneously and stably by one probe.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an eddy current flaw detection probe.

[Conventional technology]

Detection of longitudinal flaws in conventional eddy current flaw detection.

A standard comparison method was adopted in which one of a pair of test coils was applied to the test product and the other to the standard product to detect the difference. Furthermore, in order to stably detect a signal, a self-comparison method for detecting the difference between two adjacent parts is sometimes used, and in any case, two probes are required. In addition,
Related devices of this type include, for example, JP-A-62-
No. 265561 is mentioned.

[Problem to be solved by the invention]

The above conventional technology requires a standard product and requires the use of two probes, so when eddy current testing is performed on a line, it is necessary to replace the standard product according to the product to be inspected. There were problems such as the need for drive devices and maintenance for two probes.

An object of the present invention is to provide an eddy current flaw detection probe suitable for detecting both minute flaws and longitudinal flaws using a pair of probes.

Another object of the present invention is to provide an eddy current flaw detection probe suitable for performing stable signal detection by reducing the influence of feed vibration and the like.

[Means to solve the problem]

In order to achieve the above object, a plurality of coils are arranged around the circumference of one probe.

Additionally, the coil is placed on a flexible material for stable signal detection.

[Effect]

Multiple coils arranged around the circumference form several pairs, each of which acts on the crop being tested and detects the differences between the two, thereby detecting minute scratches and longitudinal edges that are present on one side or the other. It is possible to detect directional flaws simultaneously. Also, since each coil is pressed against the object to be inspected by the flexible material,
It is possible to reduce the influence of feed vibration, improve SN, and perform stable signal detection.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The half-moon-shaped bobbins 2 to 5 having a diameter slightly smaller than the inner diameter of the tube of the object to be inspected are made of an insulating material such as baked goods. Each of the bobbins 2 to 5 has a groove, and a conducting wire 6 is wound around each of the bobbins 2 to 5, and a self-induction type single type coil 7 to 1 is formed.
It becomes 0. These coils 7 to 10 are sized so that their ends overlap each other little by little when they are arranged on one circumference rather than on a complete circumference. Coil 7~
10 is attached so as to cover the outer periphery of a flexible material 11 having elasticity such as urethane. The flexible material 11 has a cutout shape of a cylinder with a diameter slightly larger than the inner diameter of the tube of the object to be inspected, and when combined with the coils 7 to 10, it becomes approximately cylindrical. In addition, a hole is made in the center of the flexible material 11, and a core material 12 made of an insulating material such as bake is attached to this hole. Each coil 7-1
The signal line from 0 is attached to a core material 12 via a flexible material 11, and further connected to the eddy current flaw detector main body. The core material 12 also serves as a connecting part with the guide part of the probe.
The probe 1 is constituted by each of the above members.

The probe 1 normally has an end face shape as shown in FIG. 3, but during flaw detection it is inserted into the interior of the object to be inspected, which is shown by the dotted line. At this time, coil 7 protruding outside the dotted line
10 is pushed against the pipe wall and further pushes against the flexible material. In this way, the flexible material 11 is appropriately compressed, and as a reaction, the coil is pressed against the inner wall of the pipe with an appropriate force. Therefore, the ends of the coils 7 to 10 are smoothed to facilitate insertion, and the portions where the coils contact the tube wall are coated with a thick resin coating to prevent wear. This makes it possible to reduce the effects of vibrations caused by waviness and feeding on the inner wall of the object to be inspected, and to reduce the SN of the flaw detection signal.
can be improved.

Signals from the coils 7 to 10 during flaw detection are processed as pairs of coils 7 and 8, and 9 and 10, which are arranged to face each other. The signal detected by coil 7 and the signal detected by coil 8 are
Processed to detect differences between each other. This cancels out changes due to undulations and the like that exist over the circumference of the inner wall of the object to be inspected, and detects only the flaws that exist at locations 119i on the circumference.

This flaw can be detected whether it is a minute flaw such as a drill hole or a flaw existing in the longitudinal direction. Furthermore, since the effects of changes in ambient temperature, etc. are canceled out, minute scratches can be detected stably. The signals of the pair of coils 9 and 10 are processed in the same way, and the entire inner wall of the pipe is inspected for flaws using the two pairs of coils.

In addition, in the case of flaw detection of loaf-in rolled tubes, etc.

Since undulations occur in the spiral shape, the positions of the paired coils must be shifted to match the pitch of the spiral wires.

According to this embodiment, it is possible to stably detect minute scratches and longitudinal scratches on the tube wall with a single probe without being affected by changes such as waviness caused by rolling etc. It is possible.

〔Effect of the invention〕

According to the present invention, fine flaws and longitudinal flaws can be detected simultaneously and stably with one probe, which has the effect of simplifying the eddy current flaw detection device and improving the reliability of output results.

[Brief explanation of the drawing]

1 is a perspective view of a probe according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of FIG. 1, and FIG. 3 is a side view of FIG. 1. 7-10...Coil, 11...Flexible material, 12...
Core material. Broom illustration

Claims (1)

[Claims] 1. An eddy current flaw detection probe characterized in that at least two half-width coils each having a flaw detection conductor wound therein are arranged in a circle.