JP2012145507A - X-ray inspection method - Google Patents
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- JP2012145507A JP2012145507A JP2011005354A JP2011005354A JP2012145507A JP 2012145507 A JP2012145507 A JP 2012145507A JP 2011005354 A JP2011005354 A JP 2011005354A JP 2011005354 A JP2011005354 A JP 2011005354A JP 2012145507 A JP2012145507 A JP 2012145507A
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Abstract
Description
本発明はＸ線検査方法に関し、特に、検査対象物の厚み変化に無関係に正確に検査対象物における欠陥等の検出を行うことが可能なＸ線検査方法に関する。 The present invention relates to an X-ray inspection method, and more particularly to an X-ray inspection method capable of accurately detecting defects and the like in an inspection object regardless of a change in thickness of the inspection object.
厚みｘの物質をＸ線が透過する場合、透過するＸ線の線束密度(Ｘ線透過量)Ｉは以下の式（１）で表され、厚みｘに対して指数関数的に低減する。なお式（１）中、Ioは物質に入射するＸ線の線束密度、μは定数である。したがって、検査対象物が厚くなると、欠陥等の存在によって検査対象物の厚みが局部的に変化してもＸ線透過量の変化は小さく、欠陥等の検出感度が低くなるため正確な検出ができないという問題があった。そこで、例えば特許文献１では、検査対象物に肉厚補正治具を装着して検査対象物の厚み変化による検出感度の低下を回避するようにしている。 When X-rays pass through a substance having a thickness x, the flux density (X-ray transmission amount) I of the transmitted X-rays is expressed by the following formula (1) and decreases exponentially with respect to the thickness x. In equation (1), Io is the flux density of X-rays incident on the substance, and μ is a constant. Therefore, when the inspection object becomes thick, even if the thickness of the inspection object locally changes due to the presence of a defect or the like, the change in the amount of X-ray transmission is small and the detection sensitivity of the defect or the like is low, so that accurate detection cannot be performed. There was a problem. Therefore, in Patent Document 1, for example, a thickness correction jig is attached to the inspection object to avoid a decrease in detection sensitivity due to a change in the thickness of the inspection object.
しかし上記公報に記載の方法では、肉厚補正治具を製作してこれを検査対象物に装着する手間を要するとともに、上記公報において指摘されているように肉厚補正治具自体の欠陥等によって検査対象物の欠陥等の正確な検出が妨げられるという問題もあった。 However, in the method described in the above publication, it takes time and labor to manufacture a thickness correction jig and attach it to the inspection object, and as pointed out in the above publication, due to defects in the thickness correction jig itself. There has also been a problem that accurate detection of a defect or the like of the inspection object is hindered.
そこで、本発明はこのような課題を解決するもので、肉厚補正治具を使用することなく簡易かつ正確に検査対象物の欠陥等の検出ができるＸ線検査方法を提供することを目的とする。 Therefore, the present invention solves such problems, and an object of the present invention is to provide an X-ray inspection method capable of easily and accurately detecting defects or the like of an inspection object without using a thickness correction jig. To do.
上記課題を解決するために、本第１発明では、異なる複数の既知の厚みを有する較正体に対してＸ線を照射して各厚みとこの部分のＸ線透過量の関係を測定するステップと、各厚みとこの部分でのＸ線透過量の関係が直線状になるように前記各厚みにおける較正値を決定するステップと、検査対象物にＸ線を照射してこのときのＸ線透過量より当該Ｘ線が透過した部分の厚みを得て、当該厚みにおける前記較正値を前記Ｘ線透過量に乗じて較正Ｘ線透過量を得るステップとを備える。 In order to solve the above problems, in the first invention, a step of irradiating a calibration body having a plurality of different known thicknesses with X-rays and measuring the relationship between each thickness and the X-ray transmission amount of this portion; Determining a calibration value at each thickness so that the relationship between each thickness and the amount of X-ray transmission at this portion is linear; and irradiating the inspection object with X-rays and the amount of X-ray transmission at this time Obtaining a thickness of a portion through which the X-ray has passed, and multiplying the X-ray transmission amount by the calibration value at the thickness to obtain a calibration X-ray transmission amount.
本第１発明によれば、Ｘ線透過量に、当該Ｘ線が透過した部分の厚みに応じた較正値を乗じて較正Ｘ線透過量を得ることにより、検査対象物の厚みが厚くなると厚み変化に対する検出感度が低下するという問題を回避でき、従来のような肉厚補正治具を使用することなく簡易かつ正確に検査対象物の欠陥等の検出をすることができる。 According to the first aspect of the present invention, the X-ray transmission amount is multiplied by a calibration value corresponding to the thickness of the portion through which the X-ray is transmitted to obtain a calibration X-ray transmission amount. The problem that the detection sensitivity to the change is reduced can be avoided, and a defect or the like of the inspection object can be detected easily and accurately without using a conventional thickness correction jig.
本第２発明では、異なる複数の既知の厚みを有する較正体に対してＸ線を照射して各厚みとこの部分のＸ線透過量の関係を測定するステップと、各厚みとこの部分でのＸ線透過量の関係が直線状になるように前記各厚みにおける較正値を決定するステップと、欠陥等の無い正常な検査対象物のＸ線透過量に基づいた画像をマスタ画像として得るステップと、マスタ画像の各部のＸ線透過量より当該Ｘ線が透過した部分の前記検査対象物の厚みを得るステップと、通常の検査対象物のＸ線透過量に基づいた画像をテスト画像として得るステップと、前記マスタ画像と前記テスト画像の各部のＸ線透過量の差分たる差分Ｘ線透過量に基づいた差分画像を算出するステップと、前記差分画像の各部の位置に対応した前記マスタ画像部分の厚みにおける前記較正値を前記各部の差分Ｘ線透過量に乗じて較正差分Ｘ線透過量を得るステップとを備える。 In the second invention, a calibration body having a plurality of different known thicknesses is irradiated with X-rays to measure the relationship between each thickness and the X-ray transmission amount of this part, and each thickness and this part Determining a calibration value at each thickness so that the relationship between the X-ray transmission amounts is linear; obtaining an image based on the X-ray transmission amount of a normal inspection object without defects as a master image; A step of obtaining a thickness of the inspection object at a portion through which the X-ray is transmitted from an X-ray transmission amount of each part of the master image, and a step of obtaining an image based on the X-ray transmission amount of a normal inspection object as a test image Calculating a difference image based on a difference X-ray transmission amount, which is a difference between the X-ray transmission amounts of each part of the master image and the test image, and the master image portion corresponding to the position of each part of the difference image In thickness And a step of obtaining a calibration difference X-ray transmission amount by multiplying the calibration value to the difference X-ray transmission amount of the respective units.
本第２発明においては、欠陥等を生じた部分のみに生じる差分Ｘ線透過量に較正値を乗じて較正差分Ｘ線透過量を得ることによって、欠陥等の位置、大きさ、深さ（高さ）等を正確に検出することができる。 In the second aspect of the present invention, the position, size, and depth (high) of the defect and the like are obtained by multiplying the differential X-ray transmission amount generated only in the portion where the defect or the like is generated by the calibration value to obtain the calibration differential X-ray transmission amount. Etc.) can be accurately detected.
上記カッコ内の符号は、後述する実施形態に記載の具体的手段との対応関係を示すものである。 The reference numerals in the parentheses indicate the correspondence with specific means described in the embodiments described later.
以上のように、本発明のＸ線検査方法によれば、肉厚補正治具を使用することなく簡易かつ正確に検査対象物の欠陥等の検出をすることができる。 As described above, according to the X-ray inspection method of the present invention, it is possible to detect a defect or the like of an inspection object simply and accurately without using a thickness correction jig.
本発明方法は、検査対象物に対しＸ線を照射してＸ線透過量に応じた透過画像を得るＸ線撮像装置と、以下に説明する各手順の処理を行うコンピュータ装置とによって実現される。 The method of the present invention is realized by an X-ray imaging apparatus that obtains a transmission image corresponding to an X-ray transmission amount by irradiating an inspection object with X-rays, and a computer apparatus that performs processing of each procedure described below. .
最初に、図１に示すような較正体１を使用して、検査対象物（ワーク）の厚みに対するＸ線透過量を測定する。すなわち本実施形態における較正体１はワークと同材で形成された長尺の角型棒体で、その一側縁には例えば１０ｍｍ、２０ｍｍ、３０ｍｍ、‥、と既知の厚みの、複数の階段部１１，１２，１３，１４，１５が形成されている。なお、図１では図解を容易にするために階段部１１〜１５の数を実際よりも少なくしてある。このような較正体１の階段部１１〜１５に対してＸ線管の管電圧を一定にして順次Ｘ線を照射して、この時のＸ線透過量を測定する。 First, the X-ray transmission amount with respect to the thickness of the inspection object (workpiece) is measured using the calibration body 1 as shown in FIG. That is, the calibration body 1 in the present embodiment is a long rectangular bar formed of the same material as the workpiece, and a plurality of stairs having a known thickness such as 10 mm, 20 mm, 30 mm,. Portions 11, 12, 13, 14, and 15 are formed. In FIG. 1, the number of steps 11 to 15 is made smaller than the actual number in order to facilitate the illustration. X-rays are sequentially irradiated to the stepped portions 11 to 15 of the calibration body 1 with the tube voltage of the X-ray tube kept constant, and the amount of X-ray transmission at this time is measured.
Ｘ線透過量の測定値の一例を図２の白角印で示す。階段部（ワーク）の厚みに対するＸ線透過量の変化曲線ｍは先に式（１）で示した指数関数となるから、ワーク厚が厚くなるとその厚み変化に対するＸ線透過量の変化割合が小さくなり、厚み変化に他する感度が低くなる。そこで、本実施形態では、ワークの厚みとＸ線透過量の関係が図２の直線ｎ状になるような各厚みにおける較正値Ｃ1,Ｃ2,Ｃ3,Ｃ4,Ｃ5,Ｃ6を決定してこれをテーブルとして記憶しておく。 An example of the measured value of the X-ray transmission amount is indicated by white square marks in FIG. Since the change curve m of the X-ray transmission amount with respect to the thickness of the staircase portion (workpiece) is the exponential function shown in the equation (1), the change rate of the X-ray transmission amount with respect to the thickness change becomes small as the workpiece thickness increases. Therefore, the sensitivity other than the thickness change is lowered. Therefore, in the present embodiment, calibration values C1, C2, C3, C4, C5, and C6 are determined for each thickness so that the relationship between the thickness of the workpiece and the amount of X-ray transmission becomes a straight line n in FIG. Store as a table.
次に、例えば図３に示すような欠陥等のないワークにＸ線を照射して各部のＸ線透過量に応じた輝度のマスタ画像Ｍを得る。そして、このマスタ画像Ｍの各部の輝度（Ｘ線透過量）より、図１の線ｍの関係を使用してワーク各部の厚みを算出しておく。 Next, for example, a workpiece having no defect as shown in FIG. 3 is irradiated with X-rays to obtain a master image M having a luminance corresponding to the X-ray transmission amount of each part. Then, the thickness of each part of the work is calculated from the luminance (X-ray transmission amount) of each part of the master image M using the relationship of the line m in FIG.
続いて、同種の一般のワークにＸ線を照射して各部のＸ線透過量に応じた輝度のテスト画像Ｎ（図４）を得る。本実施形態ではワーク上とその近傍に、径の異なる金属硬球を間隔をおいて複数配置してこれらを欠陥等の代わりとした。テスト画像Ｎ中のＡ領域の黒点が金属硬球である。 Subsequently, a general test workpiece of the same type is irradiated with X-rays to obtain a test image N (FIG. 4) having a luminance corresponding to the X-ray transmission amount of each part. In the present embodiment, a plurality of metal hard spheres having different diameters are arranged on the workpiece and in the vicinity thereof at intervals to replace these defects. The black dots in the area A in the test image N are metal hard spheres.
次のステップでは、ガウシアンフィルタ等によってそれぞれマスタ画像Ｍとテスト画像Ｎのノイズ除去を行った後、両画像Ｍ，Ｎの位置を一致させる。この後、両画像Ｍ，Ｎの差分を算出する。差分画像Ｅを図５に示す。差分画像Ｅにはテスト画像ＮのＡ領域に配設された硬球の像Ｅ1,Ｅ2,Ｅ3,Ｅ4,Ｅ5,Ｅ6のみが現れるが、硬球の像Ｅ2にはワークのエッジ部の像Ｅ21,Ｅ22が付随している。この場合の差分画像Ｅの、各部の輝度（差分Ｘ線透過量）を反転させた反転信号を図６に示すが、これより明らかなように、各硬球の像Ｅ1〜Ｅ6部分の反転信号Ｆ1,Ｆ2,Ｆ3,Ｆ4,Ｆ5,Ｆ6の信号レベルは、対応する硬球の径（厚み）に対応するものとはなっておらず、しかも、像Ｅ2に対応する反転信号Ｆ2にはワークエッジ部の像Ｅ21,Ｅ22による信号Ｆ21,Ｆ22が付随している。 In the next step, the noise of the master image M and the test image N is removed by a Gaussian filter or the like, and then the positions of the images M and N are matched. Thereafter, the difference between the images M and N is calculated. The difference image E is shown in FIG. In the difference image E, only hardball images E1, E2, E3, E4, E5, and E6 arranged in the area A of the test image N appear, but in the hardball image E2, images E21 and E22 of the edge portion of the work are shown. Is attached. FIG. 6 shows an inverted signal obtained by inverting the luminance (difference X-ray transmission amount) of each part of the difference image E in this case. As is clear from this, the inverted signal F1 of the image E1 to E6 part of each hard sphere. , F2, F3, F4, F5, F6 signal levels do not correspond to the diameter (thickness) of the corresponding hard sphere, and the inverted signal F2 corresponding to the image E2 has The signals F21 and F22 from the images E21 and E22 are accompanied.
ここにおいて、本実施形態では、差分画像Ｅの各部の輝度（差分Ｘ線透過量）に対して、当該各部のワーク厚みに対応する較正値Ｃ1〜Ｃ6を、先に準備した較正値テーブルから選択して、当該較正値Ｃ1〜Ｃ6を上記輝度に乗じて得られる較正輝度（較正差分Ｘ線透過量）よりなる較正差分画像Ｇ（図７）を得る。なお、画像Ｇ中の符号Ｇ1,Ｇ2,Ｇ3,Ｇ4,Ｇ5,Ｇ6は、テスト画像Ｎ（図４）のＡ領域に配設された硬球の像である。 Here, in the present embodiment, calibration values C1 to C6 corresponding to the work thickness of each part are selected from the previously prepared calibration value table for the luminance (difference X-ray transmission amount) of each part of the difference image E. Then, a calibration difference image G (FIG. 7) consisting of calibration luminance (calibration difference X-ray transmission amount) obtained by multiplying the luminance by the calibration values C1 to C6 is obtained. Note that symbols G1, G2, G3, G4, G5, and G6 in the image G are images of hard spheres arranged in the area A of the test image N (FIG. 4).
較正差分画像Ｇの、各部の較正輝度（較正差分Ｘ線透過量）を反転させた反転信号を図８に示す。これより明らかなように、各硬球の像Ｇ1〜Ｇ6部分の反転信号Ｈ1,Ｈ2,Ｈ3,Ｈ4,Ｈ5,Ｈ6の信号レベルは、対応する硬球の径（厚み）に正確に対応するものとなっており、しかも、反転信号Ｈ2には、反転信号Ｆ2に付随していた、ワークエッジ部の像Ｅ21,Ｅ22による信号Ｆ21,Ｆ22も付随していない。このように、較正差分画像Ｇを得ることによって、ワークに生じた欠陥等の位置、大きさ、深さ（高さ）等を正確に検出することができる。 FIG. 8 shows an inverted signal obtained by inverting the calibration luminance (calibration difference X-ray transmission amount) of each part of the calibration difference image G. As is clear from this, the signal levels of the inverted signals H1, H2, H3, H4, H5, and H6 of the image G1 to G6 portion of each hard sphere accurately correspond to the diameter (thickness) of the corresponding hard sphere. In addition, the inverted signal H2 is not accompanied by the signals F21 and F22 due to the workpiece edge images E21 and E22, which were associated with the inverted signal F2. Thus, by obtaining the calibration difference image G, it is possible to accurately detect the position, size, depth (height), etc. of a defect or the like generated in the workpiece.
１…較正体、Ｅ…差分画像、Ｇ…較正差分画像、Ｍ…マスタ画像、Ｎ…テスト画像。 DESCRIPTION OF SYMBOLS 1 ... Calibration object, E ... Difference image, G ... Calibration difference image, M ... Master image, N ... Test image.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2017062178A (en) * | 2015-09-25 | 2017-03-30 | 大同特殊鋼株式会社 | Defect detection method for product |
| JP2020118552A (en) * | 2019-01-24 | 2020-08-06 | 札幌施設管理株式会社 | Thickness detection method and piping inspection method |
| CN111521625A (en) * | 2019-05-03 | 2020-08-11 | 伟博泰有限公司 | Test block |
| CN113702408A (en) * | 2021-09-18 | 2021-11-26 | 中国航空制造技术研究院 | Variable-thickness silicon carbide fiber composite material X-ray detection method |
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2011
- 2011-01-14 JP JP2011005354A patent/JP2012145507A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2017062178A (en) * | 2015-09-25 | 2017-03-30 | 大同特殊鋼株式会社 | Defect detection method for product |
| JP2020118552A (en) * | 2019-01-24 | 2020-08-06 | 札幌施設管理株式会社 | Thickness detection method and piping inspection method |
| CN111521625A (en) * | 2019-05-03 | 2020-08-11 | 伟博泰有限公司 | Test block |
| JP2020183959A (en) * | 2019-05-03 | 2020-11-12 | ヴィポテック ゲーエムベーハー | Test piece |
| JP7014849B2 (en) | 2019-05-03 | 2022-02-01 | ヴィポテック ゲーエムベーハー | Specimen |
| US11248907B2 (en) | 2019-05-03 | 2022-02-15 | Wipotec Gmbh | Test block |
| CN111521625B (en) * | 2019-05-03 | 2024-01-02 | 伟博泰有限公司 | Test block |
| CN113702408A (en) * | 2021-09-18 | 2021-11-26 | 中国航空制造技术研究院 | Variable-thickness silicon carbide fiber composite material X-ray detection method |
| CN113702408B (en) * | 2021-09-18 | 2024-04-09 | 中国航空制造技术研究院 | X-ray detection method for variable-thickness silicon carbide fiber composite material |
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