JPS62110148A - Method for determining flaw in magnetic particle test - Google Patents

Abstract

PURPOSE:To make it possible to automatically determine a flaw, by adopting a low angle illumination method such that the irradiation angle of a light source is set to about 10 deg. and the angle of a TV camera to about 50 deg. and removing noise with a diameter of 1mm or less in an image by image processing. CONSTITUTION:A magnetic powder 4 is scattered and an object 1 to be inspected is magnetized by a magnetic powder flaw detection apparatus 3 and the unnecessary part of the scattered magnetic powder is removed by an air blower 11 so as to leave the magnetic powder film of a flaw part. The set angles of an illuminator 5 and a TV camera 6 are respectively set to about 10 deg. and about 50 deg. in the same side to a perpendicular line to photograph the surface of the object 1 to be inspected. Herein, light from the magnetic powder 4 adhered to the flaw part is irregularly reflected and a video signal is inputted to an image processor 8 in parallel to a monitor TV7. Because the signal of the residual magnetic powder capable of being removed by the blower 11 is contained in the video signal, binarization is performed on the basis of a properly set video signal. Further, by shaking off noises scattered in a spot like state using a mesh having a mesh diameter of 1mm, only flaw indication can be extracted and the output of the apparatus 8 is marked by a marker 9 and recorded on a recorder 10.

Description

Translated fromJapanese

【発明の詳細な説明】〔産業上の利用分野〕本発明は、金属材料の非破壊試験としての磁粉探傷試験
における欠陥自動判別方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic defect determination method in a magnetic particle flaw detection test as a non-destructive test of metal materials.

〔従来の技術〕[Conventional technology]

例えば溶接部欠陥等の磁粉探傷試験（以下ＭＴ試験とい
う）では、第３図に示すように、被検査体１の表面に磁
粉４を散布し、磁粉探傷器３で被検体を磁化した後エア
ブロ−装置１１で表面の磁粉を除去する。この時、被検
査体１に割れ、庇などの欠陥２があればその欠陥部に微
細な磁粉が残留し、欠陥の形状に一致した磁粉模様を呈
する。そして欠陥の有無の判別は、熟練検査員の直接目
視により判別していた。ところが、近年このような熟練
検査員による直接目視にかわってＭＴ試験の自動化に対
する要求から。For example, in a magnetic particle flaw detection test (hereinafter referred to as MT test) for weld defects, etc., as shown in Fig. 3, magnetic particles 4 are scattered on the surface of the object to be inspected 1, the object is magnetized with a magnetic particle flaw detector 3, and then an air blower is applied. - Remove magnetic particles from the surface using device 11. At this time, if the object 1 to be inspected has a crack or a defect 2 such as an eaves, fine magnetic particles remain in the defect portion and exhibit a magnetic particle pattern that matches the shape of the defect. The presence or absence of a defect was determined by direct visual inspection by a skilled inspector. However, in recent years, there has been a demand for automation of MT testing instead of direct visual inspection by skilled inspectors.

例えば第３図に示すように、照明器具５とＴＶカメラ６
を用いて欠陥を自動的に判別しようとする方法が試みら
れている。For example, as shown in FIG. 3, a lighting fixture 5 and a TV camera 6
Attempts have been made to automatically identify defects using

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

従来法の検出装置によれば、照明器具５とＴＶカメラ６
の設定角度は、それぞれθｌ−約８０°。According to the conventional detection device, the lighting equipment 5 and the TV camera 6
The setting angle of each is θl - about 80°.

θ２−約９００が一般的である。螢光磁粉を使用する場
合には、このような配置でも欠陥磁、粉模様を検出する
ことができる。しかしながら、非螢光磁粉を使用する場
合には、磁粉の色とバックグラウンド（被検査体の素地
肌の色）とのコントラストの差が少ないために、またハ
レーションなどが著しいため、明度や色相の情報だけを
用いたのでは欠陥の磁粉模様を明瞭に検出することがで
きなかった。θ2-about 900 is typical. When using fluorescent magnetic powder, defective magnetic particles and powder patterns can be detected even with such an arrangement. However, when using non-fluorescent magnetic powder, brightness and hue may be affected due to the small difference in contrast between the color of the magnetic powder and the background (the color of the skin of the object to be inspected) and significant halation. Using only information, it was not possible to clearly detect the magnetic particle pattern of the defect.

また欠陥磁粉模様以外の余分な残留磁粉をエアプローに
より除去したとしても、なお点状に散在して残る残留磁
粉の指示が出現する。Further, even if excess residual magnetic particles other than the defective magnetic particle pattern are removed by air blowing, residual magnetic particles remaining scattered in dots still appear.

従ってこのような方法においては、ＴＶ左カメラ捕えら
れたＴＶ画面には欠陥以外の映像信号が含まれているた
め、欠陥の判別が困難で。Therefore, in this method, since the TV screen captured by the left TV camera contains video signals other than defects, it is difficult to identify defects.

自動化の見込みが極めて薄いものであった。The prospects for automation were extremely slim.

〔問題点を解決するための手段〕[Means for solving problems]

本発明は、上記事情に鑑み、非螢光磁粉を散布磁化しか
つエアプローを施した被検面に光を照射しＴＶ左カメラ
撮影して探傷試験を行なうにあたり、被検面に対する光
の照射角度及びＴ■カメラ角度を垂線に対し同じ側にお
いて夫々的１０°、　　５０°に設定してＴＶ撮影し、
上記撮影によって得られたビデオ信号を適切なしきい値
で２値化したのち画像化し、その画像中の直径１閣以下
のノイズを除去する画像処理を行なうことを特徴とする
磁粉探傷欠陥判別法を提供する。In view of the above-mentioned circumstances, the present invention has been devised to provide an angle of irradiation of light to the surface to be inspected when performing a flaw detection test by irradiating light onto the surface to be inspected by scattering magnetized non-fluorescent magnetic powder and performing air blowing and photographing with the TV left camera. and T ■ Set the camera angle to 10° and 50°, respectively, on the same side with respect to the perpendicular line, and shoot the TV.
A magnetic particle flaw detection and defect discrimination method is provided, which is characterized in that the video signal obtained by the above-mentioned photographing is binarized using an appropriate threshold value, then converted into an image, and image processing is performed to remove noise with a diameter of one square inch or less in the image. provide.

〔作用〕[Effect]

即ち１本発明は、光源の照射角度を約１０°。That is, in the present invention, the irradiation angle of the light source is approximately 10°.

ＴＶ左カメラ角度を約５０°と低角度照明法を適用する
ことにより、コントラストの改善された映像信号を得る
と共に２画像処理によシ点状に散在する疑似信号を除去
することにより、欠陥信号だけが残るようにし、これに
より欠陥の自動判別を行なうものである。By setting the TV left camera angle to approximately 50° and applying a low-angle illumination method, a video signal with improved contrast is obtained, and defective signals are removed by removing spurious signals scattered in the form of dots through 2-image processing. This method allows automatic determination of defects.

〔実施例〕〔Example〕

以下第１図ないし第２図を参照して本発明の詳細な説明
する。The present invention will be described in detail below with reference to FIGS. 1 and 2.

第１図は本発明の方法による自動磁粉探傷ンステムの原
理図である。本発明方法は、磁粉４を散布して磁粉探傷
装置３で被検体を磁化し。FIG. 1 is a diagram showing the principle of an automatic magnetic particle flaw detection system according to the method of the present invention. In the method of the present invention, magnetic particles 4 are scattered and the object to be inspected is magnetized by the magnetic particle flaw detection device 3.

欠陥部の磁粉模様を残して散布した磁粉４の不要分をエ
アプロー装置１１で除去する。そして照明器具５及びＴ
Ｖカメラ６の設定角度を、垂線に対し同じ側においてそ
れぞれθｌ＝約１０°、θ２＝約５０°となるように設
定して、被検体１の表面を撮影する。An air blower 11 removes unnecessary portions of the dispersed magnetic powder 4 leaving a magnetic particle pattern in the defective part. and lighting equipment 5 and T
The surface of the subject 1 is photographed by setting the angles of the V-camera 6 so that θl = approximately 10° and θ2 = approximately 50° on the same side with respect to the perpendicular.

このような方法によれば、欠陥部以外の不要な磁粉が殆
ど付着していないことから、被検面での反射光は光源と
は反対方向に鏡面反射してしまい、ＴＶ左カメラ入らな
くなる。そのためバックグラウンドの輝度レベルを極め
て小さくすることができる。一方欠陥に付着した磁粉か
らは光が乱反射されるため、磁粉模様の輝度レベルは十
分大きい。その結果モニタＴＶ７の画面の磁粉模様のコ
ントラストは大巾に改善される。According to this method, since almost no unnecessary magnetic particles other than the defective part are attached, the reflected light from the surface to be inspected is specularly reflected in the direction opposite to the light source, and does not enter the TV left camera. Therefore, the background brightness level can be made extremely low. On the other hand, since light is diffusely reflected from the magnetic particles attached to the defect, the brightness level of the magnetic particle pattern is sufficiently high. As a result, the contrast of the magnetic particle pattern on the screen of monitor TV 7 is greatly improved.

また、コントラストの改善された磁粉模様のビデオ信号
はモニタＴｖ７と並行して２画像処理装置８に入力され
る。このビデオ信号にはエアプローを適用しても除去で
きない残留磁粉の信号が含まれているため、適切に設定
したビデオ信号レベルで２値化する。しかし２値化して
も、なおかつ微小な点状に散在するノイズが含まれたも
のとなる。通常ＭＴ試験で対象となる指示の大きさは、
１ｍｍ以上であるのに対し２点状に散在するノイズは、
約０．５　ｍｍより小さい。Further, the contrast-improved video signal of the magnetic particle pattern is input to the two-image processing device 8 in parallel with the monitor Tv7. Since this video signal includes a signal of residual magnetic particles that cannot be removed even by applying an air blower, it is binarized at an appropriately set video signal level. However, even if it is binarized, it still contains noise scattered in the form of minute points. The size of the instructions usually covered in MT exams is
The noise that is more than 1mm but scattered in two points is
Less than about 0.5 mm.

従って点状に散在するノイズは、第２図（ｂ）に示すよ
うに、直径ＩＭの大きさのメツシュ１３を用いて、ノイ
ズ１４をふるい落すことにより同図（ａ）に示すように
、欠陥指示１２だけを抽出することができる。このよう
な小粒子ノイズの除去は。Therefore, as shown in FIG. 2(b), by screening out the noise 14 using a mesh 13 having a diameter IM, as shown in FIG. Only instruction 12 can be extracted. Removal of such small particle noise.

ビデオ信号に画像処理を施すことで実現することが可能
である。従って画像処理装置８の出力は、欠陥のあった
位置を示すためのマーカ９や記録計１０に入力すること
によシ欠陥の自動判別が可能となる。This can be achieved by performing image processing on the video signal. Therefore, by inputting the output of the image processing device 8 to the marker 9 and the recorder 10 for indicating the position of the defect, automatic determination of the defect becomes possible.

〔発明の効果〕以上の説明から明らかなように２本発明によれば、ＭＴ
検査において、被検体の表面を低角度照明法によりＴＶ
カメラで撮影したビデオ信号を適切な値で２値化し、そ
の２値化画像にさらに直径１［ｎｍの大きさのメツシュ
を用いて、ノイズを除去するような画像処理を施こした
ので。[Effects of the Invention] As is clear from the above explanation, according to the present invention, MT
During inspection, the surface of the subject is illuminated with a TV using low-angle illumination.
The video signal captured by the camera was binarized with appropriate values, and the binarized image was further processed to remove noise using a mesh with a diameter of 1 nm.

欠陥の自動判別が可能である。Automatic determination of defects is possible.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は２本発明方法の一実施例の説明図。第２図は本発明方法に・おける画像処理の説明図。第３図は従来法の説明図である。ｌ・・・被検体、２・・・欠陥、３・・・磁粉探傷装置
。４・・・磁粉、５・・・照明器具、６・・・ＴＶカメラ
、７・・・モニタＴＶ、ｇ、・・・画像処理装置、９・
・・欠陥位置を示すマーカ、１０・・・記録計、１１・
・・エアブロ−装置、１２・・・欠陥信号、１３・・・
直径１ｍｍのメツシュ。FIG. 1 is an explanatory diagram of an embodiment of the method of the present invention. FIG. 2 is an explanatory diagram of image processing in the method of the present invention. FIG. 3 is an explanatory diagram of the conventional method. l...Object to be inspected, 2...Defect, 3...Magnetic particle flaw detection device. 4... Magnetic powder, 5... Lighting equipment, 6... TV camera, 7... Monitor TV, g,... Image processing device, 9...
... Marker indicating defect position, 10... Recorder, 11.
... Air blow device, 12... Defect signal, 13...
A mesh with a diameter of 1mm.

Claims (1)

Translated fromJapanese

【特許請求の範囲】[Claims]非螢光磁粉を散布磁化しかつエアブローを施した被検面
に光を照射しＴＶカメラで撮影して探傷試験を行なうに
あたり、被検面に対する光の照射角度及びＴＶカメラ角
度を垂線に対し同じ側においてそれぞれ約１０°、５０
°に設定してＴＶ撮影し、上記撮影によって得られたビ
デオ信号を適切なしきい値で２値化したのち画像化し、
その画像中の直径１ｍｍ以下のノイズを除去する画像処
理を行なうことを特徴とする磁粉探傷欠陥判別法。When performing a flaw detection test by irradiating light onto a test surface that has been magnetized by scattering non-fluorescent magnetic powder and performing air blowing, and photographing it with a TV camera, the angle of light irradiation and the TV camera angle to the test surface must be the same with respect to the perpendicular line. Approximately 10° and 50° on each side
The video signal obtained by the above shooting is binarized with an appropriate threshold value, and then converted into an image.
A magnetic particle flaw detection and defect discrimination method characterized by performing image processing to remove noise with a diameter of 1 mm or less in the image.