JP2013242223A

JP2013242223A - Eddy current flaw detection device and method

Info

Publication number: JP2013242223A
Application number: JP2012115415A
Authority: JP
Inventors: Soichi Ueno; 聡一上野; Noriyasu Kobayashi; 徳康小林; Yuko Kitajima; 裕子北島; Shigeki Maruyama; 茂樹丸山
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2012-05-21
Filing date: 2012-05-21
Publication date: 2013-12-05
Anticipated expiration: 2032-05-21
Also published as: JP5959306B2

Abstract

PROBLEM TO BE SOLVED: To suppress degradation in detection sensitivity of a flaw depending on a direction of the flaw, and detect the flaw with high sensitivity.SOLUTION: An eddy current flaw detection device includes: a flaw detection probe 11 including a plurality of excitation coils 14 and a plurality of detection coils 15 and capable of scanning the surface of a body to be tested; an exciter for supplying an excitation current to the excitation coils; and a detector for acquiring detection signals from the detection coils to detect a flaw in the body to be tested. The flaw detection probe 11 is formed by arranging two or more rows of excitation coil rows 16A and 16B each having the excitation coils 14 linearly arranged, and arranging one or more rows of detection coil rows 17A and 17B each having the detection coils linearly arranged between the excitation coil rows. An excitation current supplied by the exciter allows an eddy current to flow in the body to be tested between the excitation coils of the adjacent excitation rows so as to be inclined to the excitation coil rows. While the eddy current is alternately changed in direction to different inclined angles, the flaw of the body to be tested is detected by the detection coil and the detector.

Description

本発明は、金属構造材や小口径配管などに発生した欠陥を非破壊検査する渦電流探傷装置及び方法に関する。 The present invention relates to an eddy current flaw detection apparatus and method for nondestructive inspection of defects generated in metal structural materials, small-diameter pipes, and the like.

蒸気発生器における伝熱管等の小口径配管の外面或いは内面の欠陥検査には、磁場を利用した渦電流探傷試験（ＥｄｄｙＣｕｒｒｅｎｔＴｅｓｔｉｎｇ：ＥＣＴ）を適用した渦電流探傷装置が用いられる。 An eddy current flaw detector applying an eddy current flaw test (ECT) using a magnetic field is used for defect inspection of the outer surface or inner surface of a small-diameter pipe such as a heat transfer tube in a steam generator.

この渦電流探傷装置は、磁場を発生する励磁コイルと磁場変化を検出する検出コイルとを１つのコイルが兼ねる自己誘導型と、２つのコイルを用いる相互誘導型とがある。いずれの場合においても、励磁コイルに交流電流を供給して励磁磁場を形成し、被検査体表面に渦電流を発生させる。そして、前記渦電流の分布が欠陥により変化することを利用し、渦電流分布の変化による二次的な磁場変化を検出コイルが検出することで、欠陥の検出を行うものである。 This eddy current flaw detector includes a self-induction type in which one coil serves as an exciting coil that generates a magnetic field and a detection coil that detects a change in the magnetic field, and a mutual induction type that uses two coils. In either case, an alternating current is supplied to the exciting coil to form an exciting magnetic field, and an eddy current is generated on the surface of the object to be inspected. Then, by utilizing the fact that the distribution of the eddy current changes due to the defect, the detection coil detects the secondary magnetic field change due to the change of the eddy current distribution, thereby detecting the defect.

特許文献１には、管検査用のプローブのセンサ素子に３次元的に配置したコイル構造を適用し、管軸に対して傾斜した渦電流を被検査体に発生することで、管軸方向欠陥及び管周方向欠陥に対し検出感度を略同一に設定できるプローブ構造が開示されている。 In Patent Document 1, a coil structure arranged three-dimensionally in the sensor element of a probe for tube inspection is applied, and an eddy current inclined with respect to the tube axis is generated in the object to be inspected. In addition, a probe structure is disclosed in which detection sensitivity can be set to be substantially the same for defects in the pipe circumferential direction.

特開２００８−１９７０１６号公報JP 2008-197016 A

ＥＣＴでは、プローブの励磁コイル及び検出コイルに対する欠陥の方向によって、欠陥の検出感度が異なる。つまり、欠陥の検出感度は、励磁コイルが被検査体に形成する渦電流の方向に依存しており、欠陥に対して垂直な方向に流れる渦電流を形成させた場合には検出感度が高くなるが、欠陥に対して平行な方向に流れる渦電流を形成させた場合には検出感度が低下してしまう。 In ECT, the defect detection sensitivity differs depending on the direction of the defect with respect to the excitation coil and the detection coil of the probe. That is, the detection sensitivity of the defect depends on the direction of the eddy current formed by the exciting coil on the object to be inspected, and the detection sensitivity increases when the eddy current flowing in the direction perpendicular to the defect is formed. However, when an eddy current flowing in a direction parallel to the defect is formed, the detection sensitivity is lowered.

特許文献１におけるプローブの励磁コイルの配置では、走査方向に対して傾斜した渦電流を形成するので、管軸方向欠陥と管周方向欠陥を同程度の検出感度で検出することが可能であるが、形成する渦電流が一意の方向であるため、欠陥の方向によっては、欠陥の検出感度が著しく低下する場合が生ずる。 In the arrangement of the excitation coil of the probe in Patent Document 1, since an eddy current inclined with respect to the scanning direction is formed, it is possible to detect a defect in the tube axis direction and a defect in the tube circumferential direction with the same detection sensitivity. Since the eddy current to be formed is in a unique direction, the detection sensitivity of the defect may be significantly lowered depending on the direction of the defect.

本発明の実施形態の目的は、上述の事情を考慮してなされたものであり、欠陥の方向に依存した欠陥の検出感度の低下を抑制できると共に、欠陥を高感度に検出できる渦電流探傷装置及び方法を提供することにある。 An object of an embodiment of the present invention is made in consideration of the above-described circumstances, and is capable of suppressing a decrease in defect detection sensitivity depending on a defect direction and capable of detecting a defect with high sensitivity. And providing a method.

本発明に係る実施形態の渦電流探傷装置は、複数の励磁コイル及び検出コイルを備え被検査体の表面を走査可能な探傷プローブと、前記励磁コイルへ励磁電流を供給する励磁器と、前記検出コイルから検出信号を取得して前記被検査体の欠陥を検出する検出器と、を有する渦電流探傷装置であって、前記探傷プローブは、前記励磁コイルを直線状に配列した励磁コイル列が２列以上設置され、前記検出コイルを直線状に配列した１列以上の検出コイル列が、前記励磁コイル列間に設置されてなり、前記励磁器が供給する励磁電流によって、隣り合う前記励磁コイル列のそれぞれの前記励磁コイル間で前記被検査体に、前記励磁コイル列に対し傾斜して渦電流が流れると共に、この渦電流の向きが異なる傾斜角に交互に切り換えられ、この切り換えられた状態で前記検出コイル及び前記検出器により、前記被検査体の欠陥が検出されるよう構成されたことを特徴とするものである。 An eddy current flaw detector according to an embodiment of the present invention includes a flaw detection probe that includes a plurality of excitation coils and a detection coil and that can scan the surface of an inspection object, an exciter that supplies an excitation current to the excitation coil, and the detection An eddy current flaw detector having a detector that acquires a detection signal from a coil and detects a defect of the inspection object, wherein the flaw detection probe has two excitation coil arrays in which the excitation coils are arranged in a straight line. One or more detection coil rows arranged in a row and arranged in a straight line are arranged between the excitation coil rows, and the adjacent excitation coil rows are excited by an excitation current supplied by the exciter. An eddy current flows between the exciting coils in the test object at an inclination with respect to the excitation coil array, and the direction of the eddy current is alternately switched to a different inclination angle. By the obtained said detection coil and said detector in a state, it is characterized in that a defect of the object to be inspected is arranged to be detected.

また、本発明に係る実施形態の渦電流探傷方法は、励磁コイルを直線状に配列して２列以上設置された励磁コイル列と、検出コイルを直線状に配列し、前記励磁コイル列間に１列以上設置された検出コイル列とを備え、被検査体の表面を走査する探傷プローブを用意し、隣り合う前記励磁コイル列のそれぞれの前記励磁コイル間で前記被検査体に、前記励磁コイル列に対し傾斜する渦電流を流し、この渦電流の向きを異なる傾斜角に交互に切り換えながら、前記検出コイルにより前記被検査体の欠陥を検出することを特徴とするものである。 Further, in the eddy current flaw detection method according to the embodiment of the present invention, the excitation coils are arranged in a straight line and two or more excitation coil arrays are arranged, and the detection coils are arranged in a straight line. A flaw detection probe that scans the surface of the object to be inspected, and the excitation coil between the excitation coils of the adjacent excitation coil arrays is provided with the excitation coil. An eddy current that is inclined with respect to the column is allowed to flow, and defects of the inspection object are detected by the detection coil while alternately switching the direction of the eddy current to different inclination angles.

本発明の実施形態によれば、様々な方向の欠陥を高感度に検出できる。この結果、欠陥の方向に依存した欠陥の検出感度の低下を抑制できると共に、欠陥を高感度に検出できる。 According to the embodiment of the present invention, defects in various directions can be detected with high sensitivity. As a result, it is possible to suppress a decrease in defect detection sensitivity depending on the defect direction, and to detect defects with high sensitivity.

本発明に係る渦電流探傷装置の第１実施形態における探傷プローブを示す斜視図。The perspective view which shows the flaw detection probe in 1st Embodiment of the eddy current flaw detection apparatus which concerns on this invention. 図１の探傷プローブの励磁コイル列及び検出コイル列を展開して示す展開図。The expanded view which expands and shows the exciting coil row | line | column and detection coil row | line | column of the flaw detection probe of FIG. 図１の探傷プロープの励磁コイルへ励磁電流を供給する励磁系統を主に示すシステム構成図。The system block diagram which mainly shows the excitation system which supplies excitation current to the excitation coil of the flaw detection probe of FIG. 図１の探傷プロープの検出コイルから検出信号を取得する検出系統を主に示すシステム構成図。The system block diagram which mainly shows the detection system which acquires a detection signal from the detection coil of the flaw detection probe of FIG. 図１及び図２の励磁コイルが形成する渦電流の一例を示す説明図。FIG. 3 is an explanatory diagram showing an example of an eddy current formed by the exciting coil of FIGS. 1 and 2. 図１及び図２の励磁コイルが形成する渦電流の他の例を示す説明図。FIG. 3 is an explanatory diagram showing another example of eddy current formed by the exciting coil of FIGS. 1 and 2. 本発明に係る渦電流探傷装置の第２実施形態における探傷プローブの励磁コイル列及び検出コイル列を展開して示す展開図。The expanded view which expands and shows the exciting coil row | line | column and detection coil row | line | column of the flaw detection probe in 2nd Embodiment of the eddy current flaw detector which concerns on this invention. 図７の探傷プローブの励磁コイルへ励磁電流を供給する電磁系統を示すシステム構成図。The system block diagram which shows the electromagnetic system which supplies an exciting current to the exciting coil of the flaw detection probe of FIG. 探傷プローブの第１変形形態における励磁コイル列及び検出コイル列を展開して示す展開図。The expanded view which expands and shows the exciting coil row | line | column and detection coil row | line in the 1st modification of a flaw detection probe. 探傷プローブの第２変形形態を示す斜視図。The perspective view which shows the 2nd modification of a flaw detection probe.

以下、本発明を実施するための実施形態を図面に基づき説明する。
［Ａ］第１実施形態（図１〜図６）
図１は、本発明に係る渦電流探傷装置の第１実施形態における探傷プローブを示す斜視図であり、図３は、図１の探傷プローブの励磁コイルへ励磁電流を供給する励磁系統を主に示すシステム構成図である。 Embodiments for carrying out the present invention will be described below with reference to the drawings.
[A] First embodiment (FIGS. 1 to 6)
FIG. 1 is a perspective view showing a flaw detection probe in the first embodiment of the eddy current flaw detection apparatus according to the present invention. FIG. 3 mainly shows an excitation system for supplying an excitation current to the excitation coil of the flaw detection probe in FIG. FIG.

図３に示す渦電流探傷装置１０は、金属構造材や小口径配管、本実施形態では原子力プラントの蒸気発生器の伝熱管などにおける被検査体としての小口径配管の欠陥を非破壊検査するものである。この渦電流探傷装置１０は、複数の励磁コイル１４及び検出コイル１５を備え被検査体の表面を走査可能な探傷プローブ１１（図１）と、この探傷プローブ１１の励磁コイル１４へ励磁電流を供給する励磁器１２と、探傷プローブ１１の検出コイル１５から検出信号を取得して被検査体の欠陥を検出する検出器１３と、を有して構成される。 The eddy current flaw detector 10 shown in FIG. 3 performs nondestructive inspection of defects in a small-diameter pipe as an object to be inspected in a metal structure material, a small-diameter pipe, and in this embodiment, a heat transfer pipe of a steam generator of a nuclear power plant. It is. The eddy current flaw detection apparatus 10 includes a plurality of excitation coils 14 and a detection coil 15 and supplies an excitation current to the flaw detection probe 11 (FIG. 1) capable of scanning the surface of the object to be inspected and the excitation coil 14 of the flaw detection probe 11. And a detector 13 for detecting a detection signal from the detection coil 15 of the flaw detection probe 11 and detecting a defect of the inspection object.

ここで、図１に示す探傷プローブ１１は、蒸気発生器の伝熱管などの小口径配管内に挿入されて、この被検査体としての小口径配管の内面を走査するものである。そして、渦電流探傷装置１０は、探傷プローブ１１の励磁コイル１４へ励磁器１２から励磁電流（交流電流）を供給して励磁磁場を形成し、この励磁磁場により被検査体の表面に渦電流を発生させる。この渦電流の分布が欠陥によって変化することを利用して、渦電流の分布の変化による２次的な磁場の変化を検出コイル１５が検出することで、この検出コイル１５の検出信号から検出器１３が被検査体の欠陥を検出する。 Here, the flaw detection probe 11 shown in FIG. 1 is inserted into a small-diameter pipe such as a heat transfer pipe of a steam generator, and scans the inner surface of the small-diameter pipe as the object to be inspected. The eddy current flaw detector 10 supplies an excitation current (alternating current) from the exciter 12 to the excitation coil 14 of the flaw detection probe 11 to form an excitation magnetic field, and this excitation magnetic field generates an eddy current on the surface of the object to be inspected. generate. By utilizing the fact that the distribution of the eddy current changes due to the defect, the detection coil 15 detects a secondary magnetic field change due to the change in the eddy current distribution, so that the detector is detected from the detection signal of the detection coil 15. Reference numeral 13 detects a defect in the inspection object.

前記探傷プローブ１１は、図１及び図２に示すように、円柱形状のケーシング１９の外表面に、励磁コイル１４を直線状に等間隔に配列して２列以上（本実施形態では２列）設置された励磁コイル列１６Ａ及び１６Ｂと、検出コイル１５を直線状に等間隔に配列し、前記ケーシング１９の外表面で励磁コイル列１６Ａと１６Ｂとの間に１列以上（本実施形態では２列）設置された検出コイル列１７Ａ及び１７Ｂと、を有して構成される。 As shown in FIGS. 1 and 2, the flaw detection probe 11 has two or more rows (in this embodiment, two rows) in which excitation coils 14 are linearly arranged on the outer surface of a cylindrical casing 19 at equal intervals. The installed excitation coil rows 16A and 16B and the detection coil 15 are arranged in a straight line at equal intervals, and one or more rows (2 in the present embodiment) are arranged between the excitation coil rows 16A and 16B on the outer surface of the casing 19. The detection coil rows 17A and 17B are provided.

このうち、励磁コイル列１６Ａ及び１６Ｂについては、奇数列目（本実施形態では１列目）の励磁コイル列１６Ａの各励磁コイル１４の中心が、偶数列目（本実施形態では２列目）の励磁コイル列１６Ｂの各励磁コイル１４の中心に対し、励磁コイル列１６Ａ及び１６Ｂの列方向において前記等間隔の１／２ずらした位置に位置づけられる。また、検出コイル列１７Ａ及び１７Ｂについては、１列目の検出コイル列１７Ａの各検出コイル１５の中心が、２列目の検出コイル列１７Ｂの各検出コイル１５の中心に対し、検出コイル列１７Ａ及び１７Ｂの列方向において一致する位置に位置づけられる。更に、検出コイル列１７Ａ及び１７Ｂは、励磁コイル列１６Ａ及び１７Ｂに平行に設置されている。 Among these, for the excitation coil arrays 16A and 16B, the center of each excitation coil 14 of the excitation coil array 16A in the odd-numbered array (first array in the present embodiment) is the even-numbered array (second array in the present embodiment). With respect to the center of each excitation coil 14 of the excitation coil row 16B, the excitation coil rows 16A and 16B are positioned at positions shifted by ½ of the same interval in the row direction. Further, for the detection coil arrays 17A and 17B, the center of each detection coil 15 of the first detection coil array 17A is relative to the center of each detection coil 15 of the second detection coil array 17B. And 17B in the column direction. Furthermore, the detection coil arrays 17A and 17B are installed in parallel to the excitation coil arrays 16A and 17B.

図３に示す前記励磁器１２は位相・振幅制御機構１８を備える。この位相・振幅制御機構１８は、励磁コイル列１６Ａ及び１６Ｂのそれぞれの励磁コイル１４と個別に接続され、各励磁コイル１４へ任意の位相差及び任意の振幅の励磁電流（交流電流）を供給可能に構成される。更に、この位相・振幅制御機構１８は、励磁コイル列１６Ａ及び１６Ｂの励磁コイル１４へ、位相差及び振幅の異なる複数種類の励磁電流を経時的に切り換えて供給可能とする。 The exciter 12 shown in FIG. 3 includes a phase / amplitude control mechanism 18. This phase / amplitude control mechanism 18 is individually connected to the respective excitation coils 14 of the excitation coil arrays 16A and 16B, and can supply an excitation current (alternating current) having an arbitrary phase difference and an arbitrary amplitude to each excitation coil 14. Configured. Further, the phase / amplitude control mechanism 18 can supply a plurality of types of excitation currents having different phase differences and amplitudes over time to the excitation coils 14 of the excitation coil arrays 16A and 16B.

例えば、位相・振幅制御機構１８は、図５及び図６に示すように、１列目の励磁コイル列１６Ａにおいては、同一振幅で且つ位相差が異なる（例えば位相差０、位相差π）異なる種類の励磁電流を、隣接する励磁コイル１４に、切り換えることなく連続して供給する。また、位相・振幅制御機構１８は、２列目の励磁コイル列１６Ｂにおいては、同一振幅で且つ位相差が異なる（例えば位相差０、位相差π）異なる種類の励磁電流を、隣接する励磁コイル１４に経時的に切り換えて供給する。 For example, as shown in FIGS. 5 and 6, the phase / amplitude control mechanism 18 has the same amplitude and different phase differences (for example, phase difference 0, phase difference π) in the first excitation coil row 16A. Various types of exciting currents are continuously supplied to adjacent exciting coils 14 without switching. Further, the phase / amplitude control mechanism 18 is configured so that in the second excitation coil row 16B, different types of excitation currents having the same amplitude and different phase differences (for example, phase difference 0, phase difference π) are supplied to adjacent excitation coils. 14 to supply over time.

より具体的には、位相・振幅制御機構１８は、１列目の励磁コイル列１６Ａにおいて互いに隣接する励磁コイル１４Ａ、１４Ｂ、１４Ｃ、１４Ｄ、１４Ｅ、１４Ｆ、１４Ｇ及び１４Ｈと、２列目の励磁コイル列１６Ｂにおいて互いに隣接する励磁コイル１４Ｉ、１４Ｊ、１４Ｋ、１４Ｌ、１４Ｍ、１４Ｎ、１４Ｏ及び１４Ｐへ、次のように励磁電流を供給する。 More specifically, the phase / amplitude control mechanism 18 includes the excitation coils 14A, 14B, 14C, 14D, 14E, 14F, 14G, and 14H adjacent to each other in the first excitation coil array 16A, and the excitation in the second column. In the coil row 16B, excitation currents are supplied to the excitation coils 14I, 14J, 14K, 14L, 14M, 14N, 14O, and 14P adjacent to each other as follows.

即ち、位相・振幅制御機構１８は、１列目の励磁コイル列１６Ａにおいて一つ置きに配置された励磁コイル１４Ａ、１４Ｃ、１４Ｅ及び１４Ｇへ、位相差πの励磁電流を連続して供給し、一つ置きに配置された励磁コイル１４Ｂ、１４Ｄ、１４Ｆ及び１４Ｈへ、位相差０の励磁電流を連続して供給する。 That is, the phase / amplitude control mechanism 18 continuously supplies an excitation current having a phase difference of π to the excitation coils 14A, 14C, 14E, and 14G that are alternately arranged in the first excitation coil row 16A. An excitation current having a phase difference of 0 is continuously supplied to every other excitation coil 14B, 14D, 14F, and 14H.

また、位相・振幅制御機構１８は、２列目の励磁コイル列１６Ｂにおいて一つ置きに配置された励磁コイル１４Ｉ、１４Ｋ、１４Ｍ及び１４Ｏと励磁コイル列１４Ｊ、１４Ｌ、１４Ｎ及び１４Ｐとへ、位相差０の励磁電流と位相差πの励磁電流とを経時的に交互に切り換えて供給する。この場合、全ての励磁コイル１４Ａ〜１４Ｐへ供給される励磁電流の振幅は、略同一値である。 Further, the phase / amplitude control mechanism 18 is moved to the excitation coils 14I, 14K, 14M and 14O and the excitation coil arrays 14J, 14L, 14N and 14P which are arranged alternately in the second excitation coil array 16B. An excitation current having a phase difference of 0 and an excitation current having a phase difference of π are alternately switched over time. In this case, the amplitudes of the excitation currents supplied to all the excitation coils 14A to 14P are substantially the same value.

このような励磁電流が励磁器１２の位相・振幅制御機構１８から、隣り合う励磁コイル列１６Ａと１６Ｂのそれぞれの励磁コイル１４へ供給されることによって、これらの励磁コイル列１６Ａと１６Ｂのそれぞれの励磁コイル１４付近において被検査体に流れる渦電流は、隣り合う励磁コイル列１６Ａと１６Ｂにおいて、位相差の異なる励磁電流が流れる励磁コイル１４間（図５及び図６の斜線領域）で強め合い、位相差の同一な励磁電流が流れる励磁コイル１４間（図５及び図６の網掛け領域）で弱め合う。この結果、隣り合う励磁コイル列１６Ａと１６Ｂにおいて、位相差の異なる励磁電流が流れる励磁コイル１４を橋渡しするような渦電流α（図５の実線表示）、渦電流β（図６の実線表示）が被検査体に、励磁コイル列１６Ａ、１６Ｂの列方向に対し傾斜して流れる。 Such an excitation current is supplied from the phase / amplitude control mechanism 18 of the exciter 12 to the respective excitation coils 14 of the adjacent excitation coil arrays 16A and 16B, whereby each of the excitation coil arrays 16A and 16B. The eddy currents flowing in the object to be inspected in the vicinity of the excitation coil 14 are strengthened between the excitation coils 14 in which the excitation currents having different phase differences flow in the adjacent excitation coil arrays 16A and 16B (shaded areas in FIGS. 5 and 6). It weakens between the exciting coils 14 in which exciting currents having the same phase difference flow (shaded areas in FIGS. 5 and 6). As a result, eddy currents α (shown by solid lines in FIG. 5) and eddy currents β (shown by solid lines in FIG. 6) that bridge excitation coils 14 through which exciting currents having different phase differences flow in adjacent exciting coil arrays 16A and 16B. Flows through the object to be inspected with an inclination with respect to the direction of the excitation coil rows 16A and 16B.

これらの渦電流α、βは、励磁コイル列１６Ａ、１６Ｂの列方向に対し異なる傾斜角、即ち励磁コイル列１６Ａ、１６Ｂの列方向に対する直角方向に対し線対称な向きの渦電流である。そして、これらの渦電流α、βは、励磁コイル列１６Ｂにおいて励磁コイル１４Ｉ、１４Ｋ、１４Ｍ、１４Ｏと、励磁コイル１４Ｊ、１４Ｌ、１４Ｎ、１４Ｐとに、位相差０の励磁電流と位相差πの励磁電流とが経時的に交互に切り換えられて供給されることにより交互に生じるものである。 These eddy currents α and β are eddy currents having different inclination angles with respect to the column direction of the excitation coil arrays 16A and 16B, that is, symmetric currents with respect to a direction perpendicular to the column direction of the excitation coil arrays 16A and 16B. These eddy currents α and β are applied to the exciting coils 14I, 14K, 14M, and 14O and the exciting coils 14J, 14L, 14N, and 14P in the exciting coil array 16B. The excitation current and the alternating current are alternately generated by being switched over time.

更に、これらの渦電流α、βの少なくとも一つは、被検査体に発生した管軸方向欠陥１、管周方向欠陥２に対して略同一の角度で交差する。また、渦電流αが斜め方向欠陥３に交差する角度と、渦電流βが斜め方向欠陥４に交差する角度は略同一であり、かつ渦電流α、βが管軸方向欠陥１や管周方向欠陥２に交差する角度よりも直角に近い角度で交差する。したがって、感度の関係は、（渦電流α、βの管軸方向欠陥１に対する感度）≒（渦電流α、βの管周方向欠陥２に対する感度）＜（渦電流αの斜め方向欠陥３に対する感度）≒（渦電流βの斜め方向欠陥４に対する感度）となる。 Furthermore, at least one of these eddy currents α and β intersects the tube axis direction defect 1 and the tube circumferential direction defect 2 generated in the inspection object at substantially the same angle. In addition, the angle at which the eddy current α intersects the oblique defect 3 and the angle at which the eddy current β intersects the oblique defect 4 are substantially the same, and the eddy currents α and β are in the tube axis direction defect 1 and the tube circumferential direction. It intersects at an angle closer to a right angle than the angle intersecting the defect 2. Therefore, the relationship of sensitivity is (sensitivity of the eddy currents α and β to the tube axis direction defect 1) ≈ (sensitivity of the eddy currents α and β to the tube circumferential defect 2) <(sensitivity of the eddy current α to the oblique direction defect 3). ) ≈ (sensitivity of the eddy current β to the oblique defect 4).

図４に示すように、前記検出器１３は位相検波機構２０及びスイッチング機構２１を備え、スイッチング機構２１を介して位相検波機構２０が全ての検出コイル１５に接続される。スイッチング機構２１は、隣り合う励磁コイル列１６Ａ、１６Ｂのそれぞれの励磁コイル１４間で、励磁コイル列１６Ａ、１６Ｂの列方向に対し傾斜して流れる渦電流α、βに対応する領域の検出コイル１５を、検出信号を取得すべき検出コイル１５として経時的に選択する。これにより、位相検波機構２０は、スイッチング機構２１にて選択された検出コイル１５から検出信号を取得し、検出コイル列１７Ａ及び１７Ｂの全ての検出コイル１５から検出信号を取得する。 As shown in FIG. 4, the detector 13 includes a phase detection mechanism 20 and a switching mechanism 21, and the phase detection mechanism 20 is connected to all the detection coils 15 via the switching mechanism 21. The switching mechanism 21 includes a detection coil 15 in a region corresponding to the eddy currents α and β flowing between the excitation coils 14 of the adjacent excitation coil rows 16A and 16B in an inclined manner with respect to the row direction of the excitation coil rows 16A and 16B. Is selected over time as the detection coil 15 from which a detection signal is to be acquired. Thereby, the phase detection mechanism 20 acquires a detection signal from the detection coil 15 selected by the switching mechanism 21, and acquires a detection signal from all the detection coils 15 of the detection coil rows 17A and 17B.

更に、位相検波機構２０は、位相差が異なる複数種類の励磁電流（位相差πの励磁電流と位相差０の励磁電流）の信号を合成した合成信号を参照信号とし、この参照信号に基づき、検出コイル１５からの検出信号を検波して被検査体の欠陥を検出する。 Further, the phase detection mechanism 20 uses, as a reference signal, a synthesized signal obtained by synthesizing signals of a plurality of types of excitation currents having different phase differences (excitation current having a phase difference of π and excitation current having a phase difference of 0). A detection signal from the detection coil 15 is detected to detect a defect in the inspection object.

以上のように構成されたことから、本実施形態によれば、次の効果（１）を奏する。
（１）励磁器１２が供給する励磁電流によって、探傷プローブ１１における隣り合う励磁コイル列１６Ａ、１６Ｂのそれぞれの励磁コイル１４間で被検査体に、線対称な向きの渦電流α、βが交互に切り換えられながら流れる。これらの渦電流α、βが、被検査体に発生した管軸方向欠陥１、管周方向欠陥２に対して略同一の角度で交差し、更に、渦電流αが斜め方向欠陥３に対して、渦電流βが斜め方向欠陥４に対して略直角に交差することから、様々な方向の欠陥を高感度に検出できる。この結果、欠陥の方向に依存した欠陥の検出感度の低下を抑制できると共に、欠陥を高感度に検出できる。 With the configuration as described above, according to the present embodiment, the following effect (1) is obtained.
(1) By the excitation current supplied by the exciter 12, eddy currents α and β in the direction of line symmetry are alternately applied to the object to be inspected between the excitation coils 14 of the adjacent excitation coil arrays 16A and 16B in the flaw detection probe 11. It flows while being switched to. These eddy currents α and β intersect with the tube axis direction defect 1 and the tube circumferential direction defect 2 generated in the object to be inspected at substantially the same angle, and the eddy current α with respect to the oblique direction defect 3. Since the eddy current β intersects the oblique direction defect 4 at a substantially right angle, defects in various directions can be detected with high sensitivity. As a result, it is possible to suppress a decrease in defect detection sensitivity depending on the defect direction, and to detect defects with high sensitivity.

［Ｂ］第２実施形態（図７、図８）
図７は、本発明に係る渦電流探傷装置の第２実施形態における探傷プローブの励磁コイル列及び検出コイル列を展開して示す展開図である。図８は、図７の探傷プローブの励磁コイルへ励磁電流を供給する励磁系統を示すシステム構成図である。この第２実施形態において、前記第１実施形態と同様な部分については、同一の符号を付すことにより説明を簡略化し、または省略する。 [B] Second Embodiment (FIGS. 7 and 8)
FIG. 7 is a developed view showing an excitation coil array and a detection coil array of the flaw detection probe in the second embodiment of the eddy current flaw detection apparatus according to the present invention. FIG. 8 is a system configuration diagram showing an excitation system for supplying an excitation current to the excitation coil of the flaw detection probe of FIG. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

本実施形態の渦電流探傷装置３０が前記第１実施形態と異なる点は、探傷プローブ３１の励磁コイル列３２Ａ、３２Ｂにおける直線状に配列された隣接する励磁コイル３３の巻線方向が互いに反転されると共に、これらの励磁コイル３３が直列に接続されて励磁器３５に接続された点である。 The eddy current flaw detector 30 of the present embodiment is different from the first embodiment in that the winding directions of adjacent exciting coils 33 arranged in a straight line in the exciting coil rows 32A and 32B of the flaw detecting probe 31 are reversed. In addition, these exciting coils 33 are connected in series and connected to the exciter 35.

尚、本第２実施形態における探傷プローブ３１の励磁コイル３３の空間的配置、検出コイル１５の空間的配置及び巻き線方向、並びに検出器１３の構成は前記第１実施形態と同様である。 Note that the spatial arrangement of the excitation coil 33 of the flaw detection probe 31, the spatial arrangement and winding direction of the detection coil 15, and the configuration of the detector 13 in the second embodiment are the same as those in the first embodiment.

本第２実施形態の励磁コイル列３２Ａでは、図７に示すように、互いに隣接する励磁コイル３３Ａ、３３Ｂ、３３Ｃ、３３Ｄ、３３Ｅ、３３Ｆ、３３Ｇ及び３３Ｈのうち、一つ置きに配置された励磁コイル３３Ｂ、３３Ｄ、３３Ｆ及び３３Ｈが順巻きに、一つ置きに配置された励磁コイル３３Ａ、３３Ｃ、３３Ｅ及び３３Ｇが逆巻きに構成される。また、励磁コイル列３２Ｂでは、互いに隣接する励磁コイル３３Ｉ、３３Ｊ、３３Ｋ、３３Ｌ、３３Ｍ、３３Ｎ、３３Ｏ及び３３Ｐのうち、一つ置きに配置された励磁コイル３３Ｉ、３３Ｋ、３３Ｍ及び３３Ｏが順巻きに、一つ置きに配置された励磁コイル３３Ｊ、３３Ｌ、３３Ｎ及び３３Ｐが逆巻きに構成されている。 In the excitation coil row 32A of the second embodiment, as shown in FIG. 7, the excitation coils arranged every other one of the excitation coils 33A, 33B, 33C, 33D, 33E, 33F, 33G, and 33H adjacent to each other. The coils 33B, 33D, 33F, and 33H are configured to be forward wound, and the excitation coils 33A, 33C, 33E, and 33G that are disposed alternately are configured to be reverse wound. Further, in the exciting coil row 32B, the exciting coils 33I, 33K, 33M and 33O arranged alternately are sequentially wound among the exciting coils 33I, 33J, 33K, 33L, 33M, 33N, 33O and 33P adjacent to each other. In addition, the excitation coils 33J, 33L, 33N, and 33P arranged every other are configured in a reverse winding.

そして、図８に示すように、励磁コイル列３２Ａの励磁コイル３３Ａ〜Ｈが直列接続されて励磁器３５の位相・振幅制御機構３６に接続され、更に、励磁コイル列３２Ｂの励磁コイル３３Ｉ〜３３Ｐが直列に接続されて励磁器３５の位相・振幅制御機構３６に接続される。 As shown in FIG. 8, the excitation coils 33A to 33H of the excitation coil array 32A are connected in series and connected to the phase / amplitude control mechanism 36 of the exciter 35, and further the excitation coils 33I to 33P of the excitation coil array 32B. Are connected in series and connected to the phase / amplitude control mechanism 36 of the exciter 35.

従って、位相・振幅制御機構３６から励磁コイル列３２Ａ、３２Ｂの励磁コイル３３へ励磁電流が供給されたとき、順巻きの励磁コイル３３と逆巻きの励磁コイル３３との間で位相差がπの励磁電流が流れることになる。このため、励磁コイル列３３Ａと３３Ｂへ供給する励磁電流を同一向きまたは逆向きに切り換えることで、前記第１実施形態の場合と同様に、隣り合う励磁コイル列３２Ａ、３２Ｂのそれぞれの励磁コイル３３間で被検査体に、渦電流α、βが交互に切り換えられて流れることになる。 Accordingly, when an excitation current is supplied from the phase / amplitude control mechanism 36 to the excitation coils 33 of the excitation coil arrays 32A and 32B, an excitation having a phase difference of π between the forward winding excitation coil 33 and the reverse winding excitation coil 33. Current will flow. For this reason, by switching the excitation current supplied to the excitation coil arrays 33A and 33B in the same direction or in the opposite direction, the excitation coils 33 in the adjacent excitation coil arrays 32A and 32B, respectively, as in the case of the first embodiment. In the meantime, the eddy currents α and β are alternately switched to flow through the object to be inspected.

この結果、本実施形態においても、前記第１実施形態の場合と同様な効果（１）を奏するほか、次の効果（２）を奏する。
（２）励磁コイル列３２Ａと３２Ｂのそれぞれの励磁コイル３３が直列に接続されて励磁器３５の位相・振幅制御機構３６に接続されたことから、結線数が減少し、渦電流探傷装置３０の製作性を向上させることができる。 As a result, also in this embodiment, in addition to the same effect (1) as in the first embodiment, the following effect (2) is obtained.
(2) Since the exciting coils 33 of the exciting coil arrays 32A and 32B are connected in series and connected to the phase / amplitude control mechanism 36 of the exciter 35, the number of connections is reduced, and the eddy current flaw detector 30 Manufacturability can be improved.

以上実施形態について説明してきたが、本発明は、上述のような実施形態の具体的構成に限定されるものではなく、本発明の主旨を逸脱しない範囲で種々変形することができる。 Although the embodiment has been described above, the present invention is not limited to the specific configuration of the embodiment as described above, and various modifications can be made without departing from the gist of the present invention.

例えば、励磁コイル列は、２列の励磁コイル列１６Ａ、１６Ｂに限らず、図９に示すように、３列の励磁コイル列１６Ａ、１６Ｂ及び１６Ｃであってもよい。更に、励磁コイル列１６Ａのそれぞれの励磁コイル１４の中心は、励磁コイル１６Ｂのそれぞれの励磁コイル１４の中心に対し、励磁コイル列１６Ａ及び１６Ｂの列方向において一致した位置に位置づけられてもよい。 For example, the excitation coil arrays are not limited to the two excitation coil arrays 16A and 16B, but may be three excitation coil arrays 16A, 16B, and 16C as shown in FIG. Furthermore, the center of each excitation coil 14 of the excitation coil row 16A may be positioned at a position coincident with the center of each excitation coil 14 of the excitation coil 16B in the row direction of the excitation coil rows 16A and 16B.

また、第１実施形態において、励磁器１２の位相・振幅制御機構１８から探傷プローブ１１の励磁コイル列１６Ａ、１６Ｂにおける隣接する励磁コイル１４のそれぞれに、位相差０の励磁電流と位相差πの励磁電流ではなく、位相差−π／２の励磁電流と位相差π／２の励磁電流を供給してもよく、または、位相差がπ／２刻みで異なる励磁電流を供給してもよい。 Further, in the first embodiment, an excitation current having a phase difference of 0 and a phase difference of π are supplied from the phase / amplitude control mechanism 18 of the exciter 12 to each of the adjacent excitation coils 14 in the excitation coil arrays 16A and 16B of the flaw detection probe 11. Instead of the excitation current, an excitation current having a phase difference of −π / 2 and an excitation current having a phase difference of π / 2 may be supplied, or excitation currents having different phase differences in steps of π / 2 may be supplied.

また、第１実施形態において、励磁器１２の位相・振幅制御機構１８から探傷プローブ１１の励磁コイル列１６Ａ、１６Ｂの励磁コイル１４へ供給する励磁電流の振幅値が同一の場合を述べたが、励磁コイル１４毎に異なった振幅値の励磁電流を供給してもよい。 In the first embodiment, the case where the amplitude value of the excitation current supplied from the phase / amplitude control mechanism 18 of the exciter 12 to the excitation coil 14 of the flaw detection probe 11 is the same is described. Excitation currents having different amplitude values may be supplied for each excitation coil 14.

更に、第１及び第２実施形態の探傷プローブ１１、３１は、原子力プラントにおける蒸気発生器の伝熱管などの小口径配管に挿入されるものを述べたが、図１０に示す探傷プローブ４１のように、原子力プラントにおける原子炉管台や原子炉圧力容器の炉底部などのような金属構造材の表面上を走査するものでもよい。この探傷プローブ４１では、平板または直方体形状のケーシング４２の表面に、複数の励磁コイル１４が配列された２列以上、例えば２列の励磁コイル列１６Ａ、１６Ｂと、この励磁コイル列１６Ａ、１６Ｂ間に、複数の検出コイル１５が配列された１列以上、例えば２列の検出コイル１７Ａ、１７Ｂとが設置されている。 Furthermore, although the flaw detection probes 11 and 31 of the first and second embodiments have been described as being inserted into a small-diameter pipe such as a heat transfer tube of a steam generator in a nuclear power plant, like the flaw detection probe 41 shown in FIG. Further, it may be possible to scan the surface of a metal structure material such as a reactor nozzle in a nuclear power plant or a reactor bottom of a reactor pressure vessel. In this flaw detection probe 41, two or more rows, for example, two rows of exciting coil rows 16A and 16B in which a plurality of exciting coils 14 are arranged on the surface of a flat plate or rectangular parallelepiped casing 42, and between the exciting coil rows 16A and 16B. In addition, one or more rows, for example, two rows of detection coils 17A and 17B in which a plurality of detection coils 15 are arranged are installed.

１管軸方向欠陥
２管周方向欠陥
３、４斜め方向欠陥
１０渦電流探傷装置
１１探傷プローブ
１２励磁器
１３検出器
１４励磁コイル
１５検出コイル
１６Ａ、１６Ｂ励磁コイル列
１７Ａ、１７Ｂ検出コイル列
３０渦電流探傷装置
３１探傷プローブ
３２Ａ、３２Ｂ励磁コイル列
３３励磁コイル
３５励磁器
α、β 渦電流 DESCRIPTION OF SYMBOLS 1 Tube axial direction defect 2 Pipe circumferential direction defect 3, 4 Diagonal direction defect 10 Eddy current flaw detector 11 Flaw detection probe 12 Exciter 13 Detector 14 Excitation coil 15 Detection coil 16A, 16B Excitation coil sequence 17A, 17B Detection coil sequence 30 Eddy Current flaw detector 31 Flaw detection probe 32A, 32B Exciting coil array 33 Exciting coil 35 Exciter α, β Eddy current

Claims

複数の励磁コイル及び検出コイルを備え被検査体の表面を走査可能な探傷プローブと、
前記励磁コイルへ励磁電流を供給する励磁器と、
前記検出コイルから検出信号を取得して前記被検査体の欠陥を検出する検出器と、を有する渦電流探傷装置であって、
前記探傷プローブは、前記励磁コイルを直線状に配列した励磁コイル列が２列以上設置され、前記検出コイルを直線状に配列した１列以上の検出コイル列が、前記励磁コイル列間に設置されてなり、
前記励磁器が供給する励磁電流によって、隣り合う前記励磁コイル列のそれぞれの前記励磁コイル間で前記被検査体に、前記励磁コイル列に対し傾斜して渦電流が流れると共に、この渦電流の向きが異なる傾斜角に交互に切り換えられ、この切り換えられた状態で前記検出コイル及び前記検出器により、前記被検査体の欠陥が検出されるよう構成されたことを特徴とする渦電流探傷装置。 A flaw detection probe comprising a plurality of excitation coils and detection coils and capable of scanning the surface of the object to be inspected;
An exciter for supplying an exciting current to the exciting coil;
An eddy current flaw detector having a detector for acquiring a detection signal from the detection coil and detecting a defect of the inspection object,
In the flaw detection probe, two or more excitation coil arrays in which the excitation coils are linearly arranged are installed, and one or more detection coil arrays in which the detection coils are linearly arranged are installed between the excitation coil arrays. And
The excitation current supplied by the exciter causes an eddy current to flow between the excitation coils of the adjacent excitation coil arrays in an inclined manner with respect to the excitation coil array, and the direction of the eddy current. Are alternately switched to different inclination angles, and in this switched state, the detection coil and the detector are configured to detect defects in the object to be inspected.

前記励磁コイル列は、奇数列目の励磁コイル列における各励磁コイルの中心が、偶数列目の励磁コイル列における各励磁コイルの中心に対し、前記励磁コイル列の列方向においてずらした位置に位置づけられて構成されたことを特徴とする請求項１に記載の渦電流探傷装置。 The excitation coil array is positioned at a position where the center of each excitation coil in the odd-number excitation coil array is shifted in the array direction of the excitation coil array with respect to the center of each excitation coil in the even-number excitation coil array. The eddy current flaw detector according to claim 1, wherein the eddy current flaw detector is configured.

前記励磁器は、励磁コイル列のそれぞれの励磁コイルへ任意の位相差の励磁電流を供給可能に構成されたことを特徴とする請求項１または２に記載の渦電流探傷装置。 3. The eddy current flaw detector according to claim 1, wherein the exciter is configured to be able to supply an excitation current having an arbitrary phase difference to each excitation coil of the excitation coil array.

前記励磁器は、励磁コイル列の励磁コイルへ、位相差の異なる複数種類の励磁電流を経時的に切り換えて供給可能に構成されたことを特徴とする請求項１乃至３のいずれか１項に記載の渦電流探傷装置。 4. The apparatus according to claim 1, wherein the exciter is configured to be able to switch and supply a plurality of types of excitation currents having different phase differences over time to the excitation coils of the excitation coil array. The eddy current flaw detector described.

前記検出器は、位相差が異なる励磁電流の信号を合成した合成信号を参照信号とし、この参照信号に基づき、検出コイルからの検出信号を検波して欠陥を検出するよう構成されたことを特徴とする請求項４に記載の渦電流探傷装置。 The detector is configured to detect a defect by detecting a detection signal from a detection coil based on a synthesized signal obtained by synthesizing excitation current signals having different phase differences based on the reference signal. The eddy current flaw detector according to claim 4.

前記検出器は、隣り合う励磁コイル列のそれぞれの励磁コイル間で、前記励磁コイル列に対し傾斜して流れる渦電流に対応して、検出信号を検出すべき検出コイルを選択し、この選択した検出コイルから検出信号を取得するよう構成されたことを特徴とする請求項１乃至５のいずれか１項に記載の渦電流探傷装置。 The detector selects a detection coil for detecting a detection signal corresponding to an eddy current flowing in an inclined manner with respect to the excitation coil array between the respective excitation coils of the adjacent excitation coil arrays. The eddy current flaw detector according to any one of claims 1 to 5, wherein a detection signal is obtained from a detection coil.

前記励磁コイル列は、直線状に配列された隣接する励磁コイルの巻き線方向が互いに反転されると共に、これらの励磁コイルが直列に接続されて励磁器に接続されたことを特徴とする請求項１、２及び６項のいずれか１項に記載の渦電流探傷装置。 The exciting coil array is characterized in that the winding directions of adjacent exciting coils arranged in a straight line are reversed with each other, and these exciting coils are connected in series and connected to an exciter. The eddy current flaw detector according to any one of items 1, 2, and 6.

励磁コイルを直線状に配列して２列以上設置された励磁コイル列と、検出コイルを直線状に配列し、前記励磁コイル列間に１列以上設置された検出コイル列とを備え、被検査体の表面を走査する探傷プローブを用意し、
隣り合う前記励磁コイル列のそれぞれの前記励磁コイル間で前記被検査体に、前記励磁コイル列に対し傾斜する渦電流を流し、この渦電流の向きを異なる傾斜角に交互に切り換えながら、前記検出コイルにより前記被検査体の欠陥を検出することを特徴とする渦電流探傷方法。 An excitation coil array in which two or more excitation coils are arranged in a straight line and a detection coil array in which one or more detection coils are arranged in a straight line between the excitation coil arrays Prepare a flaw detection probe that scans the surface of the body,
An eddy current that is inclined with respect to the excitation coil array is passed between the excitation coils of the adjacent excitation coil arrays, and the detection is performed by alternately switching the direction of the eddy current to different inclination angles. An eddy current flaw detection method characterized by detecting a defect of the inspection object by a coil.