JPH06100577B2 - Enlargement method of the surface of the inspected object in ultrasonic flaw detection - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for enlarging the surface of an object to be inspected in ultrasonic flaw detection in which the ultrasonic probe is stably moved and scanned just above the edge of the surface of the object to be inspected or to the outside passing through the edge. It is a thing.

[0002]

2. Description of the Related Art An ultrasonic flaw detection method has been widely put into practical use for detecting internal flaws in an object such as a metal. At that time, the most common method is a direct contact method in which an ultrasonic probe is brought into contact with the surface of the object to be inspected through a thin film of a couplant medium to perform flaw detection. Then, unless the scratch position is known in advance, the ultrasonic probe is moved and scanned on the entire surface of the object to be inspected or a necessary part of the surface of the object to be inspected. In this case, the object to be inspected often has an edge on the surface due to cutting or the like, and in such a case, in order to perform flaw detection up to immediately below the edge, move the surface of the object to be inspected with an ultrasonic probe. The ultrasonic probe must be scanned so that the center of the ultrasonic probe reaches just above the edge of the surface of the object to be inspected or, if necessary, slightly outside thereof. Even in such a case, if the thickness of the fluid of the couplant medium existing between the contact surface of the ultrasonic probe and the surface of the object to be inspected is not constant over the front surface, a sensitivity error will occur. When performing a moving scan by grasping the acoustic probe, it is possible, although it is difficult, by performing a delicate operation on the sense and the motion by hand. However, in the automatic flaw detection method in which the ultrasonic probe is mechanically held and automatically moved and scanned, part of the contact surface of the ultrasonic probe deviates from the surface of the object to be inspected, and the contact area decreases. In the case of a mechanism in which the pressing force is controlled to be constant, the film thickness of the contact medium is reduced and a measurement error occurs. Furthermore, a detector, such as a guide, is installed around the contact surface of the ultrasonic probe, and it is constantly in contact with the surface of the object to be inspected, thereby controlling the distance between the ultrasonic probe and the surface of the object to be inspected. In this mechanism, most of the detectors go out of the edge of the object to be inspected, so control is incomplete, and the accuracy of flaw detection is reduced.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
When performing flaw detection on an inspected object with an edge using an automatic flaw detection device by the direct contact method, in most cases, the flaw detection is not performed immediately below the edge, but is performed by scanning flaw detection within a few mm or more from the edge. is there.

When it is necessary to detect flaws just below the edge of the surface of the object to be inspected by the direct contact method, most of the contact surface of the ultrasonic probe goes out of the edge and does not contact. In addition, the contacting portion must ensure a certain couplant fluid film thickness. If the ultrasonic probe is grasped and operated by hand, it requires a very delicate operation of a skilled person, but if the holding mechanism is a mechanical mechanism that holds the ultrasonic probe, it is complicated and highly advanced. It must be controlled, and in either case it is complicated or expensive.

In view of the above situation, the present invention makes it possible to inexpensively and easily perform scanning flaw detection up to directly below the edge of an object to be inspected having an edge by an automatic flaw detection apparatus by the direct contact method, and to solve the above-mentioned problems. The purpose is to provide a method for enlarging the body surface.

[0006]

SUMMARY OF THE INVENTION The present invention has a surface which is flush and smooth on the surface of an object to be inspected when performing scanning flaw detection to a position just below the edge of the object to be inspected by a direct contact method. ,
Moreover, even if the contact surface of the ultrasonic probe goes out of the edge of the object to be inspected, a mold is formed by closely adhering a plastic material that has a large attenuation to the ultrasonic wave to the area around the object to be inspected. Is on the same surface as the inside of the edge of the object to be inspected, and echoes are not reflected from the bottom surface.

[0007]

As described above, when an automatic flaw detector by the direct contact method is used to perform flaw detection directly below an object to be inspected having an ultrasonic probe, if the outside of the edge of the object to be inspected is a space. , A considerable part of the contact surface of the ultrasonic probe goes out of the edge, and the film thickness of the contact medium fluid, which is the surface distance between the contact surface of the ultrasonic probe and the object to be inspected, becomes a uniform value. Difficult to keep,
According to the enlarging method of the present invention, a plastic material having a smooth surface flush with the surface of the object to be intimately adhered to the periphery of the object to be inspected and having a large attenuation of ultrasonic waves is molded, It is possible to scan and move the ultrasonic probe in contact with the surface of the object to be inspected or on the surface of the plastic material while keeping the fluid thickness of the contact medium fluid constant, and it is also possible to easily perform flaw detection directly under the edge of the object to be inspected. Therefore, there is no reflection outside the object to be inspected because the ultrasonic wave attenuates and disappears inside the plastic material.

[0008]

EXAMPLES The present invention will be described below with reference to specific examples.

As shown in FIG. 1, a flat base plate 1 having a flat surface and a smooth surface is placed horizontally, and a mold 2 is placed thereon. The surface of the frame 2 is placed with the object 3 to be inspected in such a manner that the surface to be measured and inspected is faced down and the surface of the frame 2 is in close contact with the base plate 1. For the necessary surfaces of these base plate 1, mold 2 and inspected body 3, those which have been surface-treated with a release material in advance are used. Separately, an absorbent for ultrasonic waves, such as fine glass beads, is mixed and stirred in the undiluted solution of the plastic material in the curing container. The mixing amount may be determined experimentally, but if the plastic material is an epoxy resin and the absorbing material is a glass ball having a diameter of about 0.3 mm, the volume ratio to the plastic material is about 40%. This formwork 2
The required amount of the plastic liquid obtained by mixing and stirring the above-mentioned absorbent is poured into the inside of the object to be inspected 3 and cured.

Next, after the plastic liquid has hardened, the form 2 is removed and removed from the base plate 1 as shown in FIG. FIG. 2 is a cross section of the inspected body 3 with the surface 5 to be inspected and measured up, and 4 shows a cross section of the cured and molded plastic material that is in close contact with the periphery of the inspected body. It is flush with the surface 5 of the inspection body 3.

As described above, when the surface 5 of the inspected object 3 on which the plastic material 4 is closely molded as shown in FIG. 2 is to be detected by the direct contact method, an ultrasonic probe (not shown) is used. Even if the contact surface of) passes through the edge of the DUT 3 and goes out, the surface of the plastic material 4 is present instead of the surface 5 of the DUT 3, and since these are flush with each other, the contact medium fluid It is possible to always maintain a constant film thickness, and it is also possible to perform flaw detection immediately below the edge of the inspection object 3.

In FIG. 1 above, when the formwork 2 is viewed from above,
Although it is drawn as a square or a rectangle, the shape is arbitrary as long as it achieves the above purpose. In addition, in FIG.
Although it was drawn like a rectangular parallelepiped, the shape does not matter as long as the surface to be measured and inspected is flat. For example, when a small object to be inspected having a kamaboko-shaped cross section is obtained by the above method, it is as shown in FIG. That is, in FIG. 3, 6 is an inspected object having a kamaboko-shaped cross section, 7 is a plastic material having a surface flush with the surface of the inspected object 6, and 8 is a surface of each. It does not matter if the DUT 6 is embedded in the plastic material 7 as shown in FIG.

In the case shown in FIG. 3, the bottom surface of the inspection object 6 is not exposed, and the bottom surface of the plastic material 7 exists. The metal fitting 9 is placed on the inside, and the plastic material is poured and cured together with the metal fitting 9 as described above. As a result, as shown in FIG. 4, the metal fitting 9 can be placed mechanically and stably. In FIG. 4, 6 is an object to be inspected, 7 is a plastic material, and 8 is the surfaces of the object to be inspected 6 and the plastic material 7. 9 is a metal fitting embedded in the plastic material 7,
The shape, the number and the position of the metal fittings 9 are arbitrary. Also,
In the state shown in FIG. 3, the cured plastic material 7
However, the method of attaching an arbitrary shape and an arbitrary number of metal fittings does not matter.

When the cast plastic material forms a thin film on the surface of the object to be inspected and is cured by the above-mentioned method,
The surfaces of the plastic material and the object to be inspected may be re-polished by a means such as polishing.

Further, the plastic material and the absorbent material to be cast and cured may be of any kind as long as they meet the above-mentioned purpose. Further, the method of curing the same does not matter. However, it is not preferable that the overheat curing method requires a high temperature in consideration of the characteristics of the inspection object or the expansion of each element.

In the case of FIG. 2, when the ultrasonic probe goes out of the edge of the DUT 3 and reaches the surface of the surrounding plastic material 4, the plastic material 4 is attenuated by the ultrasonic wave. Since it is large, the echo from this bottom surface is not detected.
Since the sensitivity of the electronic circuit may be increased to detect the bottom echo of the plastic material 4, the thickness of the plastic material 4 may be increased or the ratio of the absorbing material may be increased. Further, the material of the base plate 1 and the material of the mold 2 may be of any type as long as they can achieve the above purpose.

[0017]

EFFECTS OF THE INVENTION In ultrasonic flaw detection, a necessary portion of an object to be inspected is cut into a test piece, which is often performed. In such a case, if the position of the scratch existing in the test piece is not known, it is necessary to perform flaw detection on the entire surface thereof, and the area directly below the edge of the cut test piece is not excluded. However, as described above, when using the automatic flaw detector by the direct contact method, it is difficult to detect a flaw directly below the edge, but according to the method of the present invention, it is possible to cure the base plate and the formwork with each other. By using a plastic material and a mold release material that have large attenuation for sound waves, the object to be inspected can be molded integrally with the plastic material so that flaw detection can be performed, which can be easily and inexpensively implemented. Further, using the method of the present invention, no skill is required when moving and scanning the ultrasonic probe by hand, and it is possible to easily detect a scratch just below the edge,
It is extremely beneficial in industry. Moreover, in the automatic flaw detector by the direct contact method in which the ultrasonic probe is held and automatically scanned by a mechanical mechanism, the edge of the inspected object is scanned without causing any particular problem, Since all the echoes disappear when passing through, the edge position can be detected, so that the contour of the inspection object can be clearly shown together with the position of the internal scratch.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an arrangement at the time of implementing the present invention.

FIG. 2 is a cross-sectional view of an object to be inspected and a plastic material produced by the method of the present invention.

FIG. 3 is a cross-sectional view of an inspection object and a plastic material having a shape other than a rectangular cross section.

FIG. 4 is a cross-sectional view of an object to be inspected to which a metal fitting is attached and a plastic material.

[Explanation of symbols]

 1 Base plate 2 Formwork 3 Inspected object 4 Plastic material 5 Surface 6 Kamaboko type inspected object 7 Plastic material 8 Surface 9 Metal fittings

Claims (1)

[Claims] 1. An object to be inspected when a contact surface of an ultrasonic probe is directly applied to the surface of the object to be inspected through a contact medium fluid thin film to move and scan to inspect a flaw inside the object to be inspected. The plastic material is molded to obtain a smooth surface that is in close contact with the periphery of the object and is flush with the surface of the object to be inspected, mechanically enlarging the surface of the object to be inspected and mechanically stabilizing the ultrasonic probe. A method for enlarging the surface of an object to be inspected in ultrasonic flaw detection, characterized in that the range capable of moving and scanning is extended to the edge of the surface of the object to be inspected or to the outside thereof.