JPS5826381Y2 - Ultrasonic flaw detection equipment - Google Patents

Description

[Detailed Description of the Invention] This invention mainly relates to the improvement of an apparatus for detecting flaws in thin plates using ultrasonic waves.

Conventionally, in ultrasonic flaw detection of laminations in thin steel plates, an ultrasonic probe 1 and a reflector 3 are placed in a liquid as shown in Fig. 2, and if there is a defect 4 such as a lamination in the material to be inspected, the ultrasonic wave is reflected or scattered at the defective portion such as the lamination, and the number of ultrasonic waves that reach the reflecting surface 30 is reduced.

The ultrasonic waves received by the probe 1 are shown in chronological order as shown in FIG.

That is, after the transmitted pulse T, there is a reflected wave S1 from the surface of the test material, a reflected wave R that passes through the test material and comes from the reflective surface 30, and a wave s2 that has traveled back and forth between the test materials twice.

Normally, the probe, the test material, and the reflector are arranged so that the reflected wave R comes approximately midway between the reflected waves S1 and 82, and the presence of a defect can be detected from the decrease in the R wave.

However, in this method, as shown in FIG. 3, the ultrasonic waves are spread over the material to be examined over an area equal to or greater than the area of the probe.

The size of the detectable defect depends on the
When using a probe with an ultrasonic beam cross-sectional area of 5, for example a diameter of 10 Tran, the detectable defect is about 2 Wrrn in diameter, so this method does not have very good defect detection ability.

This invention improves the detection ability of such a flaw detection device, and an embodiment of this invention is shown in Figs. 4 and 5 below.
The details will be explained according to the figures.

In FIG. 4, a probe 1 with a cylindrical lens (here, a concave lens) 1 is placed so as to connect a linear focal point 8 to the surface of the material 2 to be tested or to the center of its thickness.

Also, a reflector 3 has a reflecting surface 32 that reflects the transmitted wave 6 that has passed through the test material 2 to the opposite side of the probe 6 and retraces the original path to reach the probe 1. Place.

It is a well-known fact that the reflecting surface 32 is a cylindrical surface, and that the above movement is achieved by aligning the center of its curvature with the linear focal point 8 on the specimen 2.

The ratio of the distance 11 between the probe and the test material and the distance 12 between the test material and the reflecting surface is approximately t+'', which is 1222:1 and the transmitted R
The wave is arranged so that it appears in the middle of the 81.82 waves that have traveled back and forth between the probe and the test material.

The combination of the probe with the cylindrical lens and the reflective surface arranged as described above can detect even small defects in the material to be inspected.
Since the ultrasonic waves are intense, the attenuation of R waves is large.

In addition, since it extends linearly in the direction perpendicular to the moving direction of the test material, it has the effect that it is possible to detect flaws over a wide width with one probe.

In addition, the cylindrical reflecting surface not only efficiently returns transmitted waves, which are signal waves, to the probe, but also allows the ultrasonic waves to take the same route both ways, so the amount of signals received is reduced compared to the flat reflecting surface 30. big.

As shown in FIG. 5, the signal amount obtained in the receivable portion A is larger than that in the receivable portion B when a flat reflective surface is used, so that the signal-to-noise ratio is increased.

As described above, according to this invention, (1) defect detection ability is improved by converging ultrasonic waves on a line perpendicular to the direction of movement of the inspected material, and the effective beam width is (2) Provides an ultrasonic flaw detection device with high detection ability that uses a cylindrical reflecting surface to efficiently receive transmitted waves (signal waves) and improve the S/N ratio. can do.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of a conventional ultrasonic flaw detection device, and Figure 2 is an explanatory diagram of a conventional ultrasonic flaw detection device.
Fig. 3 is a diagram showing the cross section of the beam on the surface of the material to be inspected using the conventional method, Fig. 4 is a diagram showing an embodiment of this invention, and Fig. 5 is a diagram showing the time series of the signals shown in the figure. FIG. 3 is a diagram showing the effect of reflective surfaces (a flat surface and a cylindrical surface) on the signal amount. In the figure, 1 is a probe, 2 is a test material, 3 is a reflector, and 30
is a flat reflective surface, 32 is a cylindrical reflective surface, 4 is a defect, and 5
is the cross section of the ultrasound beam, 6 is the transmitted beam, γ is the cylindrical lens, and 8 is the collected ultrasound beam cross section according to this invention. In the drawings, the same or corresponding parts are designated by the same reference numerals.

Claims (1)

[Scope of utility model registration request] In an ultrasonic flaw detection device comprising an ultrasonic probe having a lens that focuses ultrasonic waves, and a reflector that reflects the ultrasonic waves generated from the ultrasonic probe, which are opposed to each other with a test material in between. , an ultrasonic wave characterized by forming the lens and the reflector so that the points on which the ultrasonic waves are focused form a line focus, and the line focuses of the lens and the reflector substantially coincide with each other; Flaw detection equipment.