JPS598197Y2 - A device that injects an ultrasonic beam into a curved member - Google Patents

Description

[Detailed description of the invention] This invention relates to an improvement of the parallel ultrasound beam incidence device, and it is designed so that the ultrasound waves are incident parallel to the interior of a curved object in the same way as a flat object. This is an ultrasonic incidence device that uses the principle of a concave lens.

In general, the scanning mechanism of water immersion automatic ultrasonic flaw detection equipment is a flaw detection method using a flat scanner as shown in Fig. 1. Fig. 1A shows a case where the object to be inspected is a flat plate, and Fig. 1B shows a case where the object to be tested has a curvature. This shows the case.

Normally, flat objects are tested, but when applied to objects with curvature, the sound waves are refracted at the surface of the object, making it difficult for the ultrasound to be applied to the defective part. Since it does not hit the target accurately, it is difficult to detect the defective part reliably.

In the figure, 1 is a probe, 2 is a scanning direction, 3 is a flat plate surface, 3' is a curved plate surface, 4 is a center of curvature, and 12 is a defective portion.

However, in a normal structure, the shape is not a simple flat plate, but almost always has a curvature.

Therefore, there has been a demand for an ultrasonic beam injection device that can target objects with curvature.

As a result of intensive research in response to requests related to the present invention, we found that in order to make an ultrasonic beam enter a curved object from underwater in parallel, it is possible to apply the principle of a concave lens and rotate the probe at the focal point. I discovered that.

That is, when the focal length f of a curved surface of steel, such as a concave surface, is shown from underwater, it can be calculated as shown in the following equation.

However, R is the radius of curvature, C1 is the sound wave in water, and C2 is the sound wave in steel.

For example, CI=1500 m/sec. C2=6000
If m/sec and R=75 mm, then f=100 mm.

Therefore, in order to make the ultrasonic beam parallel in steel, it is sufficient to rotate the probe at the focal point position, that is, at a position 100 mm away.

In an actual flaw detection test, it is sufficient to set the underwater distance to the distance required for flaw detection so that the above conditions are equivalently satisfied.The present invention is an ultrasonic beam injection device for ultrasonic flaw detection by water immersion method. The method is characterized in that a probe is disposed on which the ultrasonic waves are incident from the direction of the focal point formed by the surface of the curved object, and the ultrasonic beam is made to enter the object from the probe in a parallel state. That is.

An embodiment of the present invention will be described in detail based on the drawings.

As shown in FIGS. 3 and 4, a vertically movable drive shaft 9 is attached to the probe mounting device of a conventional scanner 8 via a thrust bearing 7, and a guide that follows the surface 3 of the object is attached to the lower end of the drive shaft 9. Install roller 11.

A probe holder 10 rotatable around the guide roller is connected to the guide roller.

By providing a groove in the center of this holder 10, it is possible to rotate and slide around a separately prepared rotation center 5 (focal point).

Further, a probe 1 is attached to the upper part of the holder.

Note that 6 is the locus of the probe, 13 is the rotation center support rod, and 14.
15 is a bearing, and 16 is a truck.

Next, the operation of the apparatus of the present invention will be explained. When the flat scanner scans, the drive shaft 9 moves upward or downward using this driving force, and the guide roller 11 moves the surface of the object to be examined.
Convey the movement by imitating the movement.

As this movement progresses, the probe holder 10 begins to rotate around a fixed rotation center (focal point) 5.

Therefore, the probe 1 always emits sound waves from the direction of the focal point.

As a result, the center beam of the probe is made parallel to the steel while the center of the scanner remains aligned with the point of incidence of the sound wave.

At this time, the water distance can also be kept constant regardless of the position of the probe.

According to the device of the present invention, since the sound waves hit the defective part perpendicularly, the defective part can be reliably detected.

Therefore, when we tested the structure (test piece) shown in Figure 5 to detect flaws in a flat-bottomed drill hole, we found that although the conventional method could not detect flaws, the device of the present invention was able to easily detect flaws. has.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the scanning mechanism of the water immersion automatic ultrasonic flaw detection device, Fig. 1A is an explanatory diagram when the object to be inspected is a flat plate, and Fig. 1B
is an explanatory diagram when the object to be examined has a curvature, Fig. 2 is an illustration of the principle of parallel beams, Fig. 3 is an explanatory diagram of the parallel beam incidence device attached to the flat scanner in the apparatus of the present invention, and Fig. 3A is an illustration of its principle. , FIG. 3B is a schematic explanatory diagram thereof, and FIG. 4 shows an example of a parallel beam scanning jig in the apparatus of the present invention.
FIG. 4A is a front view thereof, FIG. 4B is a side view thereof, and FIG. 5 is a perspective view showing an example of a test piece of the apparatus of the present invention. 1...Probe, 2...Scanning direction, 3.
...Flat plate surface, 3'...Curved plate surface, 4...
... Center of curvature, 5 ... Center of rotation, 6...
...Probe trajectory, 7...Bearing, 8
...Scanner, 9...Drive shaft, 10.
...Probe holder, 11...Guide roller, 12...Defect part, 13...Rotation center support rod, 14.15...・Bearing, 16・
・・・・・・Dolly.

Claims (1)

[Scope of utility model registration request] In an ultrasonic beam injection device for performing ultrasonic flaw detection using the water immersion method, a probe is arranged so that the ultrasonic waves are incident from the direction of the focal point formed by the surface of the curved object. An apparatus for injecting an ultrasonic beam into a curvature member, characterized in that the ultrasonic beam is made to enter the subject in a parallel state.