JPH08254507A - X-ray inspection method - Google Patents

Abstract

PURPOSE: To obtain an X-ray inspection method in which whether a detected flaw has been generated by an object to be inspected or by a thick connection jig can be separated clearly by a method wherein, before or after the X-ray inspection of the object to be inspected, the existence of a flaw in the correction jig is inspected by using light whose wavelength is longer than that of X-rays. CONSTITUTION: A half-split thick correction jig 3 is installed between a light source 7, whose wavelength is longer than that of X-rays, for a laser beam or the like and a photodetector 8 such as a photodiode or the like so as to face the light source. The position of the light source 7 is set to the same direction as a direction in which X-rays are incident in an X-ray inspection, and transmitted light T is received by the photodetector 8 on the side on which light from the light source 7 has passed the jig 3. In addition, the photodetector 8 is arranged at the outside of the jig 3 in a direction at right angles to incident light from the light source, and scattered light D inside the jig 3 is received. An optical inspection is performed before or after an X-ray inspection, the flaw or the position of the jig 3 is aligned with the flaw or the position of an object, to be inspected, which has been inspected by X-rays, and the flaw or the position of the object to be inspected is confirmed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CV cable, an accessory thereof, and the like, and when an internal defect is inspected by irradiating an X-ray from the surface, an X-ray is carried out by mounting a thickness correction jig on the detected object. It relates to the inspection method.

[0002]

2. Description of the Related Art Conventionally, a thickness correction jig has been generally used in X-ray inspection. This means, for example,
Japanese Unexamined Patent Publication No. 4-27811, FIGS. 6 to 7 and FIG. 7 are described below in the section of Description of the Related Art. That is, for example, when inspecting for the presence or absence of an internal defect in a power cable having a conductor covering layer made of plastic and its connection (inspection), X-rays are transmitted through the covering layer, and the image density according to the transmitted X-ray dose. There is a method of inspecting defects inside the coating layer by forming a difference, transferring the difference onto a sensitive material, and analyzing an image on the sensitive material.
In the case of such a power cable inspection, as shown in the cross section of the power cable in FIG. 4, a cable made up of the conductor 11 and the coating layer 12 is transmitted through the coating layer 12 in a direction in which X-rays having a uniform projection distribution are orthogonal to the cable. Then, the X-ray transmission paths I ₄ and I ₁ in the X-ray coating layer 12 are located at the position P ₄ close to the conductor 11 and the insulating layer 12
Different at position P ₁ near the outside of. That is, since the thickness of the object to be inspected by the X-ray inspection varies depending on the place, in this case, the thickness of the coating layer 12 of the power cable which is the subject is almost equal in the entire transmission path as shown in FIG. A half-split body 13 having a rectangular or square outer cross-section with two cracks is provided inside the half-crack joint surface, and a recess 14 corresponding to the outer contour of the insulating layer of the power cable is provided. It is made of the same material as the insulating layer and is inserted into the power cable and mounted, and at the time of X-ray inspection, the transmission amount of X-rays from the X-ray source 15 is made uniform. It is called a thickness correction jig.

[0003]

In the above thickness correction jig, the transmitted dose exponentially fluctuates when the thickness of the object varies depending on the location, and the size of the defect that can be found by inspection is a sensitive material. It is used to correct the unevenness of the parts of the film, but if it is not corrected, the inspection function will be deteriorated, and if it is not corrected, the image will be saturated. The thin part can be inspected as a uniform state. By the way, assuming that there is a wall thickness correction jig that has a defect therein, and the size of the defect is 50 μm, and the upper limit of the performance of the X-ray apparatus is 50 μm, the defect of the above size is found by the preliminary inspection. Or it is in the marginal area where it cannot be found, and at the time of actual inspection, it is sometimes visible and sometimes it is not visible. The reproducibility of X-ray photography is not so good, and since it is a human who looks at an X-ray film to inspect it, it is inevitable that it will be visible or invisible near the upper limit of performance as described above.

In such a state, in the X-ray inspection of the power cable, the inspector marks dozens of defect candidates on one film. Most are uneven or scratched film. By taking consecutive shots with two films, if there is unevenness or scratches on the film, it does not matter, but the overlapping candidates are taken out as defects. As already mentioned, the inspector marks dozens of invisible and invisible defects, that is, candidates of defects that are close to the upper limit of the performance of the X-ray apparatus. is there.
On the other hand, the allowable defect size of the power cable is at the limit of the performance of the X-ray device, that is, at the limit of whether it is visible or invisible, and this visible or invisible state is clearly visible or invisible. At the very least, it is necessary to sufficiently guarantee the thickness correction jig that receives X-ray irradiation at the same time.

[0005]

In order to solve the above-mentioned problems, it is possible to detect the presence / absence of a defect in the wall thickness correction jig by an optical inspection means which can be made higher in sensitivity than X-rays, and to check the position if any. Then, together with this, the result of the X-ray inspection and the defect in the cable are examined. In this case, if the material of the jig is determined, it may be determined that the wavelength of the light having a high permeability to the substance, for example, infrared light. The wavelength of light used for measurement is light having a wavelength longer than that of X-rays. For example, if visible light is determined, the jig may be made of a transparent material at that wavelength. The optical inspection of the wall thickness correction jig may be performed before or after the X-ray inspection of the subject. By performing the optical inspection of the jig, the defects found by this inspection, A defect in the subject or a defect in the wall thickness correction jig is confirmed by checking the positions.

Defects found by X-ray inspection are substances having a different X-ray absorptivity as compared with substances having a defect-free surrounding structure, and include, for example, voids (small X-ray absorptivity) and metallic foreign matters ( X-ray absorption rate is large). And it is difficult to find substances with similar X-ray absorption rates. The substance found by inspection with light other than X-rays is a substance having a light absorption rate different from that of the surrounding substance or a substance having a refractive index different from that of the surrounding substance. For example, the voids and metallic foreign matter in the insulating resin have different absorptivity from the synthetic resin, and the resin foreign matter has different refractive index and absorptivity from the synthetic resin, which can be detected by light inspection. Has a low absorptivity and is hard to find, and even if it is a substance that cannot be found by light because it is close to the X-ray absorptivity, it can be found because the refractive index is often different, and the types of defects that can be found increase. In addition, the size of the defect that can be detected with higher sensitivity than that of the X-ray apparatus and that can be found is small. Further, as the wavelength of light, visible light to near-infrared light is commercially available C
Since it is easy to detect with a CD camera or photodiode, it is easy to handle. However, when the material used as the thickness correction jig does not transmit visible light to near-infrared light, for example, if the jig is polyethylene at room temperature, use a wavelength (far infrared) at which the material transmits light. . In short, any wavelength may be used, but it must pass through the thickness correction jig.

[0007]

EXAMPLES The practice of the present invention will be described below. As already mentioned, FIG. 3 is an explanatory diagram of an X-ray inspection method for a power cable including an insulating layer made of synthetic resin. Between the X-ray source 1 and the X-ray film 2, the power cable 4 is fitted into the recess 14 of the half-cracked thickness correction jig 3 described above, and the meat is applied to the radiation from the X-ray source 1. Thickness correction jig 3
As described above, the covering layer 5 of the power cable is
The X-ray film is photographed by correcting the transmission path of X-rays that pass through. Instead of X-ray film, imaging plate,
A CCD can also be used. In this case, the thickness correction jig 3 is made of a material having the same X-ray absorptivity as the insulating layer of the power cable to be inspected.

Prior to the X-ray inspection or after the inspection, a foreign matter inspection of the thickness correction jig is performed. FIG. 1 is an explanatory diagram of a defect inspection method of a thickness correction jig. As shown in the figure, a light source having a wavelength longer than the X-ray, for example, laser light, LED light, or a light bulb is used as a light source 7, and a photodiode, facing the light source 7,
A CCD is used as a light receiving element 8, and a half-divided thickness correction jig 3 is installed between them. In the X-ray inspection, the position of the light source 7 is set in the same direction as the X-ray incident direction, and the light beam from the light source 7 receives the transmitted light T on the side that has passed through the thickness correction jig 3. Further, since the scattered light D of the projection light beam from the light source 7 in the thickness correction jig 3 is received, the surface outside the thickness correction jig 3 in the direction orthogonal to the direction of the projection light beam from the light source. The light receiving element 8 for receiving the scattered light D is arranged so as to oppose to.

If the procedure of the above measuring method is changed such that the position of the light source position with respect to the thickness correction jig is changed and the positions of the transmitted light and scattered light receiving elements are correspondingly changed, The location of defects such as internal voids and foreign matters can be detected by the change of the received light current due to the transmission, scattering, absorption, and refraction of the light. In this embodiment, the inspection for the half-thickness thickness correction jig has been described, but the same inspection is performed for other half-breakage jigs.

FIG. 2 shows that in the inspection of the thickness correction jig for defects, by filling the circumference of the jig with a liquid having a refractive index close to that of the jig, the inspection light due to the shape of the thickness correction jig is generated. The structure which corrects refraction is shown. As shown in the figure, the thickness correction jig 3 is filled with a liquid 10 having a refractive index close to that of the thickness correction jig 3 in a rectangular parallelepiped container 9 made of a light-transmitting substance which is recognized to have no foreign matter. The light source 7 and the light receiving element 8 for receiving the transmitted light T are arranged on the outer sides of the container 9 facing each other, and the scattered light due to the light beam passing through the thickness correction jig 3 is detected. A light receiving element 8 for detecting scattered light D is arranged outside the container in a direction different from the direction of the transmitted light of the tool 3. The inspection method is the same as that already explained.

[0011]

According to the present invention, the presence or absence of defects in the thickness correction jig used during X-ray inspection is inspected prior to or after the X-ray inspection, so that it can be detected by X-ray inspection. It is possible to clearly separate whether the defect is caused by the detected object or the correction jig.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an optical inspection for presence / absence of a defect of a wall thickness correction jig applied in an X-ray inspection method of the present invention.

FIG. 2 is an explanatory diagram of another optical inspection for presence / absence of a defect of the wall thickness correction jig applied in the X-ray inspection method of the present invention.

FIG. 3 is an explanatory diagram of a method of inspecting a power cable for defects by X-ray.

FIG. 4 is a diagram for explaining the difference in the X-ray transmission path, which is a problem in the conventional defect inspection of the power cable by X-rays.

FIG. 5 is an explanatory diagram of a wall thickness correction jig used in a defect inspection of a power cable by X-ray.

[Explanation of symbols]

 1 X-ray source 2 X-ray film 3 Thickness correction jig 4 Power cable 5 Covering layer 6 Conductor 7 Light source 8 Light receiving element 9 Container 10 Liquid with a refractive index close to that of the thickness correction jig

Claims (2)

[Claims] 1. A wall thickness correction jig mounted on an object to be inspected by an X-ray inspection in order to make uniform the X-ray dose when the thickness of the object to be inspected differs depending on the location. The defect is inspected by transmitting, scattering, absorbing, refracting long light, and the presence and position of the defect are inspected. An X-ray inspection method characterized in that the defect and position of the thickness correction jig are also combined to confirm the defect and position of the subject. 2. The X according to claim 1, wherein the thickness correction jig is held in a liquid having a refractive index close to that of the correction jig to confirm defects and positions of the thickness correction jig. Line inspection method.