JPS6010169A - Ultrasonic flaw detection of thin material - Google Patents

Abstract

PURPOSE:To elevate the defect detection sensitivity of a thin inner cylinder or the like by making an ultrasonic wave radiated with an adjacent vibrator incident upon the position where an ultrasonic wave reflected on the inner surface of work reflects on the outer surface thereof again. CONSTITUTION:A flaw detection element 13 is made up of five small vibrators 141-145, for example, 1mm. wide and 10mm. deep. The interval between the vibrators 141-145 is so set that an ultrasonic wave radiated with an adjacent vibrator is incident upon the position where an ultrasonic wave reflected on the inner surface 12a of work 12 reflects on the outer surface 12b again. Therefore, according to the method of the present invention, an ultrasonic wave of a large amplitude can be propagated to the work by adding incident ultrasonic waves in the same phase without cancelling each other as in the past thereby enabling a high defect detection sensitivity in a thin cylinder or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic flaw detection method for thin-walled materials (objects) such as thin-walled cylinders.

Conventionally, in order to perform ultrasonic flaw detection on a thin-walled cylinder with a wall thickness of about 1 mt, a water immersion probe 2 having a transducer 1 with a diameter of about 10 mm is used to detect thin-walled cylinders in water 3, as shown in Fig. 1. This is done by injecting ultrasonic waves into the cylinder 4. However, in this method, as shown in FIG. 1, the ultrasonic waves 5 directly incident on the thin-walled cylinder 4 and the ultrasonic waves 6 reflected on the inner surface of the thin-walled cylinder 4 overlap; This has the disadvantage that the two waves cancel each other out (interference), resulting in a significant decrease in defect detection sensitivity.

The present invention uses a probe in which a plurality of small transducers are arranged in parallel with respect to the subject, and the intervals between each transducer are set so that the ultrasonic waves reflected from the inner surface of the subject are reflected back to the outside. The ultrasonic wave emitted by the adjacent transducer should be made incident to the position where it is reflected by the surface, and the angle of incidence of the ultrasonic wave from each transducer to the subject should be determined, as well as the distance between each transducer and the subject surface. An attempt is made to provide an ultrasonic flaw detection method for thin-walled materials that achieves improved defect detection sensitivity by selecting selected transducers so that the ultrasonic waves emitted from each vibrator have the same phase in the test object. It is something.

Embodiments of the present invention will be described below with reference to FIGS. 3 and 4. u
and spot them.

FIG. 3 is a schematic diagram for explaining the ultrasonic flaw detection method of the present invention, in which 11 is water and 12 is, for example, a diameter of 10Qz.
vi, a thin cylinder (subject) with wall thickness Q, 7 wrπ, and also. 13 in the figure is a probe, and this probe 13 consists of five small transducers 14. ~14. It consists of These oscillators 14. ~14. The mutual spacing is set such that the ultrasonic wave emitted by the stop transducer is incident on the position where the JlE sound wave reflected from the inner surface 12a of the subject 12 is reflected again from the outer surface 12b. 6, 151-1 in the figure
5. is each vibrator 14. ~14. an ultrasonic beam emitted from 16. ~16. is an ultrasonic wave traveling through the object 12, 17 is a defect, and 18 is a reflected wave from the defect J7.

Next, the ultrasonic flaw detection method of the present invention will be explained with reference to FIG. 3 mentioned above.

First, the vibrator 14. Ultrasonic 15. By emitting , the ultrasonic wave 151 propagates throughout the water 11 and enters the subject 12 at four points, where it is refracted and becomes an ultrasonic wave 16° that travels through the subject 12. Ultrasound 16. is subject 1
The transducer 1 is reflected at the inner surface 12a of the transducer 2, further reflected at the point B of the outer surface 12b, and travels through the object 12.
41 and the ultrasonic wave 15 emitted from the adjacent transducer 142
．． Since each vibrator is arranged so that B
After this point, the two waves overlap and proceed (=0).Here, the incident angle θ of the ultrasonic wave 152 of the transducer 142 and the distance between the transducer 142 and the surface of the object 12 must be appropriately selected (Nieri , ultrasonic waves by the transducer 14. and the transducer 142
As shown in FIG. 4, the ultrasonic waves caused by the transducer 14. Ultrasonic waves 16 traveling through the subject 12 due to It is possible to obtain an ultrasonic wave 162 with a larger amplitude compared to the above.

Similar conditions were applied to the oscillator 14. ~14. Subject 12 using
If the points 0, D, and E are filled, the ultrasonic waves emitted from each transducer will be added together with the same phase, as shown in 16! in Figure 4. l, 16. ．． Ultrasonic waves with a gradually larger amplitude of 16° can be obtained. Ultrasound 16. The beam propagates in a zigzag pattern through the thickness of the object 12, and if there is a defect 17 shown in FIG. 3, a defect echo (reflected wave) 18 is generated. This echo 18 is transmitted to the oscillator 14. Defects are detected using the rainbow probe 14. Therefore, in the method of the present invention, the incident ultrasonic waves and the ultrasonic waves in the object do not cancel each other out as in the conventional method, but are added in the same phase and can propagate large amplitude ultrasonic waves to the object. Defect detection sensitivity can be improved.

In the above example, water was interposed between the vibrator and the surface of the subject, but the same effect can be obtained by interposing a liquid such as oil or glycerin, or a solid such as acrylic resin or organic glass instead of water. You can expect good results.

As described in detail above, according to the present invention, it is possible to provide an ultrasonic flaw detection method for thin-walled materials that achieves improved defect detection sensitivity using simple means.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram for explaining the conventional ultrasonic flaw detection method, Fig. 2 is a waveform diagram showing the relationship between incident ultrasonic waves and reflected ultrasonic waves according to the conventional method, and Fig. 3 is an implementation of the present invention. FIG. 4 is a schematic diagram for explaining the ultrasonic detection method of the present invention. ... Water, 12 ... Subject, 13 ... Probe, 14, □-14a ... Vibrator, 161-16. ...Ultrasound that travels throughout the object,
17... Defect, 18... Reflected wave (defect echo).

Claims (1)

[Claims] When performing ultrasonic flaw detection on a test object made of a thin material using a probe in which a plurality of small transducers are arranged in parallel, ultrasonic waves are incident on the test object from these transducers. The spacing between each transducer is set so that the ultrasound waves from adjacent transducers are incident at the position where the ultrasound waves incident on the object are reflected on the outer surface, and the ultrasound waves emitted from each transducer are reflected on the object's outer surface. An ultrasonic flaw detection method for thin materials characterized by selecting the incident angle of ultrasonic waves to a test object and the distance between each vibrator and the test object so that they are in the same phase.