JP5750208B2 - Eddy current flaw detection probe, eddy current flaw detection apparatus, and eddy current flaw detection method - Google Patents
Eddy current flaw detection probe, eddy current flaw detection apparatus, and eddy current flaw detection method Download PDFInfo
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Description
本願発明は、励磁素子と検出素子からなる渦電流探傷プローブを所定の方向へ走査（移動）して、被検査体（被探傷体）のキズを検出する渦電流探傷プローブ、渦電流探傷装置及び渦電流探傷方法に関する。 The present invention relates to an eddy current flaw detection probe, an eddy current flaw detection device, which scans (moves) an eddy current flaw probe composed of an excitation element and a detection element in a predetermined direction to detect a flaw in a test object (flaw detection object), and The present invention relates to an eddy current flaw detection method.
被検査体の探傷面には、渦電流探傷プローブの走査方向に対して様々な方向に進展する（延在する）キズが存在するが、一般の渦電流探傷プローブは、キズの進展方向により検出感度が異なるため、キズを十分に検出できない場合があった。その点に鑑み、いずれの方向へ進展するキズも、即ち全方向のキズを検出できるように構成した渦電流探傷プローブが提案されている。
図８（ａ）の渦電流探傷プローブは、回転式の検出コイルを備えた渦電流探傷プローブを用いた例であり（特許文献１参照）、図８（ｂ）の渦電流探傷プローブは、直交する２個の励磁コイルを備えている（特許文献２参照）。
There are flaws that extend (extend) in various directions with respect to the scanning direction of the eddy current flaw detection probe on the surface to be inspected, but general eddy current flaw detection probes are detected based on the flaw propagation direction. Since the sensitivity is different, scratches may not be detected sufficiently. In view of this point, an eddy current flaw detection probe has been proposed which is configured to detect flaws extending in any direction, that is, flaws in all directions.
The eddy current flaw detection probe shown in FIG. 8A is an example using an eddy current flaw detection probe having a rotary detection coil (see Patent Document 1), and the eddy current flaw detection probe shown in FIG. The two exciting coils are provided (see Patent Document 2).
まず図８（ａ）の渦電流探傷プローブについて説明する。
渦電流探傷プローブ１１は、円形（ドウナツ状）の励磁コイル１１１と四角形の検出コイル１１２からなる。励磁コイル１１１は、コイル軸が被検査体Ｔの探傷面に垂直になる（コイル面は平行になる）ように配置し、検出コイル１１２は、コイル軸が被検査体Ｔの探傷面と平行になる（コイル面は垂直になる）ように配置してある。検出コイル１１２は、軸Ｐ１を中心に回転する。渦電流探傷プローブ１１は、検出コイル１１２を回転しながら、走査方向ＳＣの方向へ移動する。
なおここで本願は、コイルの巻線に囲まれた開口部の面（コイル軸と直交する面）をコイル面と呼ぶ。
First, the eddy current flaw detection probe shown in FIG.
The eddy current flaw detection probe 11 includes a circular (doughnut-shaped) excitation coil 111 and a square detection coil 112. The exciting coil 111 is arranged so that the coil axis is perpendicular to the flaw detection surface of the inspection object T (the coil surface is parallel), and the detection coil 112 is arranged so that the coil axis is parallel to the flaw detection surface of the inspection object T. (The coil surface is vertical). The detection coil 112 rotates around the axis P1. The eddy current flaw detection probe 11 moves in the scanning direction SC while rotating the detection coil 112.
In the present application, the surface of the opening (surface perpendicular to the coil axis) surrounded by the coil winding is referred to as a coil surface.
被検査体Ｔの探傷面には、走査方向ＳＣの方向へ進展するキズ（以下長手キズと呼ぶ）Ｆ１、走査方向ＳＣの方向と直交する方向へ進展するキズ（以下直交キズと呼ぶ）Ｆ２、走査方向ＳＣの方向と４５度の方向へ進展するキズＦ３が存在する。その場合、検出コイル１１２は、回転しながらキズＦ１，Ｆ２，Ｆ３を通過するから、いずれのキズに対してもコイル面が各キズの長手方向（進展方向）と直交するときがある。したがって検出コイル１１２は、いずれの方向のキズも高感度で検出できる。 The flaw detection surface of the inspection object T has a flaw (hereinafter referred to as a longitudinal flaw) F1 that develops in the direction of the scanning direction SC, a flaw that develops in a direction orthogonal to the direction of the scanning direction SC (hereinafter referred to as an orthogonal flaw) F2, There is a flaw F3 that progresses in the direction of 45 degrees with respect to the scanning direction SC. In that case, since the detection coil 112 passes through the flaws F1, F2, and F3 while rotating, the coil surface may be orthogonal to the longitudinal direction (progression direction) of each flaw. Therefore, the detection coil 112 can detect scratches in any direction with high sensitivity.
次に図８（ｂ）の渦電流探傷プローブについて説明する。
渦電流探傷プローブ１２は、四角形の励磁コイル１２１ａ，１２１ｂと円形（ドウナツ状）の検出コイル１２２からなる。励磁コイル１２１ａ，１２１ｂは、コイル軸が直交し（コイル面も直交する）、コイル軸が被検査体Ｔの探傷面と平行になる（コイル面は直交する）ように配置し、検出コイル１２２は、コイル軸が被検査体Ｔの探傷面に垂直になる（コイル面は平行になる）ように配置してある。渦電流探傷プローブ１２は、走査方向ＳＣの方向へ移動してキズＦ１，Ｆ２，Ｆ３を探傷する。
図８（ｂ）の渦電流探傷プローブの場合、２種類の渦電流探傷方法がある。第１の渦電流探傷方法は、励磁コイル１２１ａ，１２１ｂに周波数が同じで位相が９０度異なる励磁電流を供給して回転磁界を発生し、検出コイル１２２の検出電圧を励磁電流と同じ周波数の参照信号により同期検波して渦電流探傷信号を取り出す。第２の渦電流探傷方法は、励磁コイル１２１ａ，１２１ｂに周波数が異なる励磁電流を供給し、各励磁コイルの励磁中に発生する検出コイル１２２の検出電圧を夫々励磁電流と同じ周波数の参照信号により同期検波して２つの渦電流探傷信号を取り出し、両渦電流探傷信号を別々に、或いは加算して探傷に用いる。渦電流探傷プローブ１２は、直交する２個の励磁コイル１２１ａ，１２１ｂにより被検査体Ｔに渦電流を発生（誘導）するから、進展方向の異なるキズを検出することができる。
Next, the eddy current flaw detection probe shown in FIG.
The eddy current flaw detection probe 12 includes rectangular excitation coils 121a and 121b and a circular (doughnut-shaped) detection coil 122. The exciting coils 121a and 121b are arranged so that the coil axes are orthogonal (coil surfaces are also orthogonal), and the coil axes are parallel to the flaw detection surface of the inspection object T (the coil surfaces are orthogonal), and the detection coil 122 is The coil axis is arranged so as to be perpendicular to the flaw detection surface of the inspection object T (the coil surface is parallel). The eddy current flaw detection probe 12 moves in the scanning direction SC to detect flaws F1, F2, and F3.
In the case of the eddy current flaw detection probe shown in FIG. 8B, there are two types of eddy current flaw detection methods. In the first eddy current flaw detection method, an excitation current having the same frequency and a phase different by 90 degrees is supplied to the excitation coils 121a and 121b to generate a rotating magnetic field, and the detection voltage of the detection coil 122 is referred to the same frequency as the excitation current. An eddy current flaw detection signal is extracted by synchronous detection with the signal. In the second eddy current flaw detection method, excitation currents having different frequencies are supplied to the excitation coils 121a and 121b, and the detection voltage of the detection coil 122 generated during the excitation of each excitation coil is determined by a reference signal having the same frequency as the excitation current. Two eddy current flaw detection signals are extracted by synchronous detection, and both eddy current flaw detection signals are used separately or added together for flaw detection. Since the eddy current flaw detection probe 12 generates (induces) eddy current in the inspection object T by the two exciting coils 121a and 121b orthogonal to each other, it is possible to detect scratches having different development directions.
前記図８（ａ）の回転式検出コイルからなる渦電流探傷プローブは、検出コイルを回転しなければならないから、探傷の高速化に限度があり、またメンテナンスの問題がある。一方図８（ｂ）の直交型の励磁コイルからなる渦電流探傷プローブは、渦電流探傷プローブの構成や操作は簡単であるが、前記第１の渦電流探傷方法は、キズの方向により渦電流探傷信号の位相が変わるため、位相による雑音の分離が困難になる。また前記第２の渦電流探傷方法は、キズの進展する方向によりキズの検出感度が大きく異なり、例えば、直交キズの検出感度は高いが、長手キズの検出感度は低いため、長手キズの渦電流探傷信号対雑音の比（Ｓ／Ｎ）が悪くなってしまう。
本願発明は、従来の前記問題点に鑑み、直交型の検出コイルからなる渦電流探傷プローブ、その渦電流探傷プローブを備えた渦電流探傷装置とその渦電流探傷プローブを用いて行う渦電流探傷方法において、長手キズの渦電流探傷信号のＳ／Ｎを改善することを目的とする。
The eddy current flaw detection probe comprising the rotary detection coil shown in FIG. 8 (a) has a limitation in speeding up flaw detection and a maintenance problem because the detection coil must be rotated. On the other hand, the eddy current flaw detection probe including the orthogonal excitation coil shown in FIG. 8B has a simple configuration and operation of the eddy current flaw detection probe. However, the first eddy current flaw detection method uses the eddy current flaw detection method depending on the direction of the scratch. Since the phase of the flaw detection signal changes, it becomes difficult to separate noise by the phase. In the second eddy current flaw detection method, the flaw detection sensitivity differs greatly depending on the direction of flaw development. For example, the detection flaw of orthogonal flaws is high, but the detection flaw of longitudinal flaws is low. The ratio (S / N) of the flaw detection signal to noise is deteriorated.
In view of the above-mentioned problems, the present invention is an eddy current flaw detection probe comprising an orthogonal detection coil, an eddy current flaw detection device including the eddy current flaw detection probe, and an eddy current flaw detection method performed using the eddy current flaw detection probe. An object of the present invention is to improve the S / N of an eddy current flaw detection signal having a longitudinal flaw.
本願発明は、その目的を達成するため、請求項１に記載の渦電流探傷方法は、２個の励磁素子と１個の検出素子からなり、該励磁素子は導電板からなり、２個の導電板は、探傷面対向面が探傷面に平行で、探傷面対向面の励磁電流の方向は交差し走査方向中心線に対して±θとなるように配置してある、若しくは該励磁素子はコイルからなり、２個のコイルは、コイル軸が探傷面に平行で、コイル軸は交差し走査方向中心線に対して±θとなるように配置してある渦電流探傷プローブ、又は該渦電流探傷プローブにおいて、前記θは、４５度である渦電流探傷プローブを用いて、
２個の励磁素子を周波数及び位相が同じ励磁電流により交互に励磁し、一方及び他方の励磁素子の励磁中に検出素子に発生した検出電圧を励磁電流と同じ周波数の参照信号により同期検波し、２つの渦電流探傷信号を取り出してその２つの渦電流探傷信号の和信号又は差信号を発生し、その和信号又は差信号を用いてキズを評価することを特徴とする。
請求項２に記載の渦電流探傷方法は、請求項１に記載の渦電流探傷方法において、前記参照信号は、励磁電流と位相が同じ参照信号と励磁電流と位相が９０度異なる参照信号からなり、前記２個の励磁素子の一方及び他方の励磁中に２つの参照信号により同期検波し、参照信号毎に２つの渦電流探傷信号を取り出してその２つの渦電流探傷信号の和信号又は差信号を発生し、２つの和信号又は差信号を用いてキズを評価することを特徴とする。
請求項３に記載の渦電流探傷方法は、２個の励磁素子と１個の検出素子からなり、該励磁素子は導電板からなり、２個の導電板は、探傷面対向面が探傷面に平行で、探傷面対向面の励磁電流の方向は交差し走査方向中心線に対して±θとなるように配置してある、若しくは該励磁素子はコイルからなり、２個のコイルは、コイル軸が探傷面に平行で、コイル軸は交差し走査方向中心線に対して±θとなるように配置してある渦電流探傷プローブ、又は該渦電流探傷プローブにおいて、前記θは、４５度である渦電流探傷プローブを用いて、
２個の励磁素子を周波数及び位相が同じ励磁電流により交互に励磁し、一方及び他方の励磁素子の励磁中に検出素子に発生した検出電圧を励磁電流と同じ周波数の参照信号により同期検波し、２つの渦電流探傷信号を取り出してその２つの渦電流探傷信号の和信号又は差信号を発生し、その和信号又は差信号を用いてキズを評価すると同時にその２つの渦電流探傷信号を用いてキズを評価することを特徴とする。
請求項４に記載の渦電流探傷方法は、請求項３に記載の渦電流探傷方法において、前記参照信号は、励磁電流と位相が同じ参照信号と励磁電流と位相が９０度異なる参照信号からなり、前記２個の励磁素子の一方及び他方の励磁中に２つの参照信号により同期検波し、参照信号毎に２つの渦電流探傷信号を取り出してその２つの渦電流探傷信号を用いてキズを評価することを特徴とする。
請求項５に記載の渦電流探傷装置は、２個の励磁素子と１個の検出素子からなり、該励磁素子は導電板からなり、２個の導電板は、探傷面対向面が探傷面に平行で、探傷面対向面の励磁電流の方向は交差し走査方向中心線に対して±θとなるように配置してある、若しくは該励磁素子はコイルからなり、２個のコイルは、コイル軸が探傷面に平行で、コイル軸は交差し走査方向中心線に対して±θとなるように配置してある渦電流探傷プローブ、又は該渦電流探傷プローブにおいて、前記θは、４５度である渦電流探傷プローブ、
２個の励磁素子に周波数及び位相が同じ励磁電流を交互に供給する励磁電源、励磁電流と同じ周波数の参照信号を供給する参照信号源、一方及び他方の励磁素子の励磁中に、検出素子に発生した検出電圧を参照信号により同期検波する同期検波器、同期検波器の出力から２つの渦電流探傷信号を取り出してその２つの渦電流探傷信号の和信号又は差信号を発生する手段、その和信号又は差信号を用いてキズを評価する手段を備えていることを特徴とする。
請求項６に記載の渦電流探傷装置は、２個の励磁素子と１個の検出素子からなり、該励磁素子は導電板からなり、２個の導電板は、探傷面対向面が探傷面に平行で、探傷面対向面の励磁電流の方向は交差し走査方向中心線に対して±θとなるように配置してある、若しくは該励磁素子はコイルからなり、２個のコイルは、コイル軸が探傷面に平行で、コイル軸は交差し走査方向中心線に対して±θとなるように配置してある渦電流探傷プローブ、又は該渦電流探傷プローブにおいて、前記θは、４５度である渦電流探傷プローブ、
２個の励磁素子に周波数及び位相が同じ励磁電流を交互に供給する励磁電源、励磁電流と同じ周波数の参照信号を供給する参照信号源、一方及び他方の励磁素子の励磁中に、検出素子に発生した検出電圧を参照信号により同期検波する同期検波器、同期検波器の出力から２つの渦電流探傷信号を取り出してその２つの渦電流探傷信号の和信号又は差信号を発生する手段、その和信号又は差信号を用いてキズを評価すると同時にその２つの渦電流探傷信号を用いてキズを評価する手段を備えていることを特徴とする。
In order to achieve the object of the present invention, the eddy current flaw detection method according to claim 1 includes two excitation elements and one detection element, and the excitation element includes a conductive plate and includes two conductive elements. The plate is arranged so that the flaw detection surface facing surface is parallel to the flaw detection surface, and the excitation current directions of the flaw detection surface facing surface intersect and are ± θ with respect to the center line in the scanning direction. The two coils have an eddy current flaw detection probe arranged such that the coil axis is parallel to the flaw detection surface, the coil axes cross each other and ± θ with respect to the center line in the scanning direction, or the eddy current flaw detection In the probe, the θ is 45 degrees using an eddy current flaw detection probe,
Two excitation elements are excited alternately by the excitation current having the same frequency and phase, and the detection voltage generated in the detection element during excitation of one and the other excitation element is synchronously detected by a reference signal having the same frequency as the excitation current, Two eddy current flaw detection signals are taken out, a sum signal or a difference signal of the two eddy current flaw detection signals is generated, and scratches are evaluated using the sum signal or difference signal.
The eddy current flaw detection method according to claim 2 is the eddy current flaw detection method according to claim 1 , wherein the reference signal includes a reference signal having the same phase as the excitation current and a reference signal having a phase different from the excitation current by 90 degrees. During the excitation of one or the other of the two excitation elements, synchronous detection is performed by two reference signals, two eddy current flaw detection signals are extracted for each reference signal, and the sum signal or difference signal of the two eddy current flaw detection signals is extracted. And scratches are evaluated using two sum signals or difference signals.
The eddy current flaw detection method according to claim 3 is composed of two excitation elements and one detection element, the excitation element is composed of a conductive plate, and the two conductive plates have a flaw detection surface opposite to the flaw detection surface. Parallel, the direction of the excitation current on the surface facing the flaw detection surface intersects and is arranged to be ± θ with respect to the scanning direction center line, or the excitation element is composed of a coil, and the two coils are coil axes. Is parallel to the flaw detection surface, the coil axis intersects, and the eddy current flaw detection probe is arranged so as to be ± θ with respect to the scanning direction center line, or in the eddy current flaw detection probe, the θ is 45 degrees Using an eddy current flaw detection probe,
Two excitation elements are excited alternately by the excitation current having the same frequency and phase, and the detection voltage generated in the detection element during excitation of one and the other excitation element is synchronously detected by a reference signal having the same frequency as the excitation current, Two eddy current flaw detection signals are taken out, a sum signal or a difference signal of the two eddy current flaw detection signals is generated, and scratches are evaluated using the sum signal or difference signal, and at the same time, the two eddy current flaw detection signals are used. It is characterized by evaluating scratches.
The eddy current flaw detection method according to claim 4 is the eddy current flaw detection method according to claim 3 , wherein the reference signal includes a reference signal having the same phase as the excitation current, and a reference signal having a phase different from the excitation current by 90 degrees. During the excitation of one and the other of the two exciting elements, synchronous detection is performed with two reference signals, two eddy current flaw detection signals are extracted for each reference signal, and scratches are evaluated using the two eddy current flaw detection signals. It is characterized by doing.
The eddy current flaw detection apparatus according to claim 5 includes two excitation elements and one detection element, the excitation elements include a conductive plate, and the two conductive plates have a flaw detection surface opposite to the flaw detection surface. Parallel, the direction of the excitation current on the surface facing the flaw detection surface intersects and is arranged to be ± θ with respect to the scanning direction center line, or the excitation element is composed of a coil, and the two coils are coil axes. Is parallel to the flaw detection surface, the coil axis intersects, and the eddy current flaw detection probe is arranged so as to be ± θ with respect to the center line in the scanning direction. Eddy current testing probe,
An excitation power supply that alternately supplies excitation currents having the same frequency and phase to the two excitation elements, a reference signal source that supplies a reference signal having the same frequency as the excitation current, and a detection element during excitation of one and the other excitation elements A synchronous detector for synchronously detecting the generated detection voltage with a reference signal, means for taking out two eddy current flaw detection signals from the output of the synchronous detector and generating a sum signal or a difference signal of the two eddy current flaw detection signals, and the sum Means for evaluating a scratch using a signal or a difference signal is provided.
The eddy current flaw detection device according to claim 6 includes two excitation elements and one detection element, the excitation elements include a conductive plate, and the two conductive plates have a flaw detection surface facing surface on the flaw detection surface. Parallel, the direction of the excitation current on the surface facing the flaw detection surface intersects and is arranged to be ± θ with respect to the scanning direction center line, or the excitation element is composed of a coil, and the two coils are coil axes. Is parallel to the flaw detection surface, the coil axis intersects, and the eddy current flaw detection probe is arranged so as to be ± θ with respect to the scanning direction center line, or in the eddy current flaw detection probe, the θ is 45 degrees Eddy current testing probe,
An excitation power supply that alternately supplies excitation currents having the same frequency and phase to the two excitation elements, a reference signal source that supplies a reference signal having the same frequency as the excitation current, and a detection element during excitation of one and the other excitation elements A synchronous detector for synchronously detecting the generated detection voltage with a reference signal, means for taking out two eddy current flaw detection signals from the output of the synchronous detector and generating a sum signal or a difference signal of the two eddy current flaw detection signals, and the sum Means is provided for evaluating scratches using the signal or difference signal and simultaneously evaluating scratches using the two eddy current flaw detection signals.
本願発明の渦電流探傷プローブを用いると、２個の励磁素子により発生する渦電流は、走査方向に並んで発生する渦電流は同相になり、走査方向と直交する方向に並んで発生する渦電流は、逆相になる。また励磁素子と励磁電源の接続を変えるとその位相関係は、逆になる。したがって前者の場合には、渦電流探傷信号の和を取ることにより、また後者の場合には、渦電流探傷信号の差を取ることにより、長手キズに起因する渦電流探傷信号を増大し、直交キズに起因する渦電流探傷信号を抑制できるから、長手キズに起因する渦電流探傷信号のＳ／Ｎを改善することができる。 When the eddy current flaw detection probe according to the present invention is used, the eddy current generated by the two exciting elements is in-phase with the eddy current generated side by side in the scanning direction, and is generated side by side in the direction orthogonal to the scanning direction. Is out of phase. When the connection between the excitation element and the excitation power source is changed, the phase relationship is reversed. Therefore, in the former case, the sum of the eddy current flaw detection signals is taken, and in the latter case, the difference between the eddy current flaw detection signals is taken to increase the eddy current flaw detection signal due to the longitudinal flaw, Since the eddy current flaw detection signal caused by the scratch can be suppressed, the S / N of the eddy current flaw detection signal caused by the longitudinal flaw can be improved.
本実施形態の渦電流探傷プローブは、２個の励磁素子と１個の検出素子からなり、励磁素子が導電板の場合、２個の導電板は、励磁電流の方向が交差しその交差部の中心を通り渦電流探傷プローブの走査方向に平行な線（走査方向中心線）において左右対称になるように配置してある。また２個の導電板は、交互に励磁するように構成してある。２個の導電板を励磁すると、渦電流探傷プローブの走査方向に並んで発生する渦電流は、同相になり、渦電流探傷プローブの走査方向と直交する方向に並んで発生する渦電流は、逆相になる。その特性を利用して、渦電流探傷プローブの走査方向に進展するキズ（長手キズ）に起因する渦電流探傷信号は加わり合い、渦電流探傷プローブの走査方向と直交する方向に進展するキズ（直交キズ）に起因する渦電流探傷信号は打ち消し合うように構成してある。その結果長手キズに起因する渦電流探傷信号は増大し、直交キズに起因する渦電流探傷信号は抑制されるとともに、後述するように走査方向と直交する方向に進展する電磁気特性の変化に起因する雑音も抑制されて、長手キズの渦電流探傷信号のＳ／Ｎを改善することができる。 The eddy current flaw detection probe according to this embodiment includes two excitation elements and one detection element. When the excitation element is a conductive plate, the two conductive plates intersect each other in the direction of the excitation current. They are arranged so as to be symmetrical on a line passing through the center and parallel to the scanning direction of the eddy current flaw detection probe (scanning direction center line). Further, the two conductive plates are configured to be excited alternately. When two conductive plates are excited, the eddy currents generated in the scanning direction of the eddy current testing probe are in phase, and the eddy currents generated in the direction perpendicular to the scanning direction of the eddy current testing probe are reversed. Become a phase. Using this characteristic, eddy current flaw detection signals due to flaws (longitudinal flaws) that develop in the scanning direction of the eddy current flaw detection probe are added together, and flaws that propagate in the direction perpendicular to the scanning direction of the eddy current flaw detection probe (orthogonal) Eddy current flaw detection signals due to scratches are configured to cancel each other. As a result, the eddy current flaw detection signal due to the longitudinal flaw increases, the eddy current flaw detection signal due to the orthogonal flaw is suppressed, and it is caused by a change in electromagnetic characteristics that develops in a direction perpendicular to the scanning direction as will be described later. Noise is also suppressed, and the S / N of the eddy current flaw detection signal having a longitudinal flaw can be improved.
次に渦電流探傷の際に発生する雑音についてみると、被検査体の探傷面の電磁気的特性は、キズ以外に探傷面の微細な凹凸等形状の変化や材質の変化等によっても変わるから、渦電流探傷信号には、キズ以外の電磁気的特性の変化に起因して発生する信号、即ち雑音が混入している。雑音は、渦電流探傷信号と同様に、渦電流探傷プローブの走査方向に平行な方向へ進展する電磁気特性の変化に起因する雑音よりも、その走査方向と直交する方向へ進展する電磁気特性の変化に起因する雑音の方が大きくなる。しかし前記のように直交キズに起因する渦電流探傷信号を抑制すると、渦電流探傷プローブの走査方向と直交する方向の雑音も抑制される。したがって本実施形態の渦電流探傷装置は、直交キズに起因する渦電流探傷信号を抑制するとともに、走査方向と直交する方向へ進展する電磁気特性の変化に起因する雑音も抑制できるから、長手キズに起因する渦電流探傷信号のＳ／Ｎを大幅に改善できる。 Next, looking at noise generated during eddy current flaw detection, the electromagnetic characteristics of the flaw detection surface of the object to be inspected also change due to changes in the shape of the flaw detection surface such as fine irregularities and changes in the material, etc. The eddy current flaw detection signal is mixed with a signal generated due to a change in electromagnetic characteristics other than scratches, that is, noise. As with eddy current flaw detection signals, noise changes in the electromagnetic characteristics that propagate in the direction perpendicular to the scanning direction rather than noise caused by changes in the electromagnetic characteristics that propagate in the direction parallel to the scanning direction of the eddy current flaw detection probe. The noise caused by is larger. However, if the eddy current flaw detection signal due to the orthogonal flaw is suppressed as described above, the noise in the direction orthogonal to the scanning direction of the eddy current flaw detection probe is also suppressed. Therefore, the eddy current flaw detection apparatus according to the present embodiment can suppress the eddy current flaw detection signal caused by the orthogonal flaw and also suppress the noise caused by the change in electromagnetic characteristics that propagate in the direction orthogonal to the scanning direction. The S / N of the resulting eddy current flaw detection signal can be greatly improved.
図１〜図７により本願発明の実施例について説明する。
なお各図に共通の部分は、同じ符号を使用している。
An embodiment of the present invention will be described with reference to FIGS.
In addition, the same code | symbol is used for the part common to each figure.
図1、図２により本願発明の実施例に係る渦電流探傷プローブを説明する。
図１は、渦電流探傷プローブの励磁素子と検出素子の配置例、及び励磁素子により発生（誘導）する渦電流を示す。
渦電流探傷プローブＰは、励磁素子として２個の導電板ＥＰ１，ＥＰ２と検出素子として１個の検出コイルＤＣを備えている。
An eddy current flaw detection probe according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows an arrangement example of excitation elements and detection elements of an eddy current flaw detection probe, and eddy currents generated (induced) by the excitation elements.
The eddy current flaw detection probe P includes two conductive plates EP1 and EP2 as excitation elements and one detection coil DC as a detection element.
まず図１（ａ）について説明する。
導電板ＥＰ１，ＥＰ２は、被検査体の探傷面に対向する面（探傷面対向面と呼ぶ）を被検査体の探傷面に平行に配置し、探傷面対向面を流れる励磁電流ｉｅ１，ｉｅ２の方向（励磁電流の方向）が交差するように配置してあり、その交差部の中心ＰＣを通り、渦電流探傷プローブＰの走査方向ＳＣと平行な線（走査方向中心線と呼ぶ）に対して±θとなるように配置してある。即ち導電板ＥＰ１，ＥＰ２は、励磁電流の方向が走査方向中心線において左右対称となるように配置してある。θは、０度より大きく９０度より小さい範囲に設定するが、４５度前後に設定すると、０〜９０度の方向（全方向）に進展するキズを高感度で検出できる。
なお励磁素子として２個の励磁コイルを用いる場合には、両励磁コイルのコイル軸又はコイル面が走査方向ＳＣに対して±θとなるように配置する。また検出素子は、巨大磁気抵抗効果を用いたＧＭＲ素子を用いることもできる。
First, FIG. 1A will be described.
The conductive plates EP1 and EP2 are arranged such that a surface (referred to as a flaw detection surface facing surface) facing the flaw detection surface of the inspection object is arranged in parallel with the flaw detection surface of the inspection object, and excitation currents ie1 and ee2 flowing through the flaw detection surface facing surface. Are arranged so that the directions (excitation current directions) intersect each other, pass through the center PC of the intersection, and are parallel to the scanning direction SC of the eddy current flaw probe P (referred to as the scanning direction center line). They are arranged to be ± θ. That is, the conductive plates EP1 and EP2 are arranged such that the direction of the excitation current is symmetrical with respect to the center line in the scanning direction. θ is set in a range larger than 0 degree and smaller than 90 degrees. However, when set to around 45 degrees, a scratch that develops in a direction of 0 to 90 degrees (all directions) can be detected with high sensitivity.
When two exciting coils are used as the exciting elements, they are arranged so that the coil axes or the coil surfaces of both exciting coils are ± θ with respect to the scanning direction SC. The detection element can also be a GMR element using a giant magnetoresistance effect.
導電板ＥＰ１，ＥＰ２は、スイッチＳＷ１１，ＳＷ１２を介して交互に励磁電源ＲＶへ接続して、交互に励磁する。即ち励磁電源ＲＶは、スイッチＳＷ１１，ＳＷ１２が接点ａ１側へ切替わっているとき、導電板ＥＰ１に接続され、接点ａ２側へ切替わっているとき導電板ＥＰ２に接続される。スイッチＳＷ１１，ＳＷ１２は、時分割で交互に切替えて探傷するが、時分割でなく、スイッチＳＷ１１，ＳＷ１２を接点ａ１側へ切替えたまま、渦電流探傷プローブＰを走査して第１回目の探傷を行い、次にスイッチＳＷ１１，ＳＷ１２を接点ａ２側へ切替えて第１回目の探傷と同じ場所を再度走査して第２回目の探傷を行うこともできる。その場合、スイッチＳＷ１１，ＳＷ１２の切替え制御は簡単になるが、同じ場所を２回走査することになるから、探傷時間が長くなる。 The conductive plates EP1 and EP2 are alternately connected to the excitation power source RV via the switches SW11 and SW12 and are excited alternately. That is, the excitation power source RV is connected to the conductive plate EP1 when the switches SW11 and SW12 are switched to the contact a1 side, and is connected to the conductive plate EP2 when the switches SW11 and SW12 are switched to the contact a2 side. The switches SW11 and SW12 are alternately switched in time division to detect flaws. However, instead of time division, the switches SW11 and SW12 are switched to the contact a1 side to scan the eddy current flaw detection probe P to perform the first flaw detection. It is also possible to perform the second flaw detection by switching the switches SW11 and SW12 to the contact a2 side and then scanning again at the same place as the first flaw detection. In this case, the switching control of the switches SW11 and SW12 becomes simple, but the same place is scanned twice, so that the flaw detection time becomes long.
次に図１（ｂ１）〜（ｂ３）により、導電板ＥＰ１，ＥＰ２の励磁電流によって被検査体の探傷面に発生する渦電流ついて説明する。
図１（ｂ１）において、導電板ＥＰ１に励磁電流ｉｅ１を流すと励磁電流ｉｅ１の両側（励磁電流の方向の両側）に位相が１８０度異なる（逆相の）渦電流ｉｕ１１，ｉｕ１２が発生する。また図１（ｂ２）において、導電板ＥＰ２に励磁電流ｉｅ２を流すと励磁電流ｉｅ２の両側に位相が１８０度異なる渦電流ｉｕ２１，ｉｕ２２が発生する。
Next, eddy currents generated on the flaw detection surface of the object to be inspected by the excitation currents of the conductive plates EP1 and EP2 will be described with reference to FIGS. 1 (b1) to (b3).
In FIG. 1B1, when an exciting current ie1 is passed through the conductive plate EP1, eddy currents iu11 and iu12 that are 180 degrees out of phase (in opposite phases) are generated on both sides of the exciting current ie1 (both sides in the direction of the exciting current). Further, in FIG. 1 (b2), when an exciting current ie2 is passed through the conductive plate EP2, eddy currents iu21 and iu22 that are 180 degrees out of phase are generated on both sides of the exciting current ie2.
図１（ｂ１）と図１（ｂ２）を重ねると、図１（ｂ３）のようになる。即ち図１（ａ）の渦電流探傷プローブＰが発生する渦電流は、図１（ｂ３）のようになる。図１（ｂ３）の場合、渦電流ｉｕ１１，ｉｕ２１は同相になり、渦電流ｉｕ２２，ｉｕ１２も同相になる。一方渦電流ｉｕ１１，ｉｕ２２は逆相になり、渦電流ｉｕ２１，ｉｕ１２も逆相になる。したがって走査方向ＳＣと平行な方向へ進展するキズ（長手キズ）に起因して発生する渦電流探傷信号、例えば渦電流ｉｕ１１，ｉｕ２１によって発生する渦電流探傷信号は、加わり合って増大する。渦電流ｉｕ２２，ｉｕ１２についても同様である。一方走査方向ＳＣに直交する方向へ進展するキズ（直交キズ）に起因して発生する渦電流探傷信号、例えば渦電流ｉｕ１１，ｉｕ２２によって発生する渦電流探傷信号は、打ち消し合って抑制される。渦電流ｉｕ２１，ｉｕ１２についても同様である。 When FIG. 1 (b1) and FIG. 1 (b2) are overlapped, FIG. 1 (b3) is obtained. That is, the eddy current generated by the eddy current testing probe P in FIG. 1A is as shown in FIG. 1B3. In the case of FIG. 1 (b3), the eddy currents iu11 and iu21 are in phase, and the eddy currents iu22 and iu12 are also in phase. On the other hand, the eddy currents iu11 and iu22 are out of phase, and the eddy currents iu21 and iu12 are out of phase. Therefore, an eddy current flaw detection signal generated due to a flaw (longitudinal flaw) that develops in a direction parallel to the scanning direction SC, for example, an eddy current flaw detection signal generated by the eddy currents iu11 and iu21, is added and increased. The same applies to the eddy currents iu22 and iu12. On the other hand, eddy current flaw detection signals generated due to flaws extending in a direction orthogonal to the scanning direction SC (orthogonal flaws), for example, eddy current flaw detection signals generated by the eddy currents iu11 and iu22 are canceled and suppressed. The same applies to the eddy currents iu21 and iu12.
以上のように２個の導電板ＥＰ１，ＥＰ２によって発生する渦電流の内、走査方向ＳＣと平行な方向に並んで発生する渦電流（例えば渦電流ｉｕ１１，ｉｕ２１）により発生する渦電流探傷信号は増大し、走査方向ＳＣと直交する方向に並んで発生する渦電流（例えば渦電流ｉｕ１１，ｉｕ２２）により発生する渦電流探傷信号は抑制される。したがって長手キズに起因する渦電流探傷信号の検出感度は、高くなり、直交キズに起因する渦電流探傷信号の検出感度は、低くなる。
図１（ｂ３）において、励磁電流ｉｅ１，ｉｅ２の方向が逆になると、渦電流ｉｕ１１〜ｉｕ２２の方向も逆になるから、長手キズに起因する渦電流探傷信号の検出感度と、直交キズに起因する渦電流探傷信号の検出感度の関係は、図１（ｂ３）の場合と同じである。しかし励磁電流ｉｅ１，ｉｅ２のいずれか一方が逆になると、走査方向ＳＣと平行な方向に並んで発生する渦電流により発生する渦電流探傷信号は抑制され、走査方向ＳＣと直交する方向に並んで発生する渦電流により発生する渦電流探傷信号は増大する。
As described above, of the eddy currents generated by the two conductive plates EP1 and EP2, the eddy current flaw detection signal generated by the eddy currents generated side by side in the direction parallel to the scanning direction SC (for example, eddy currents iu11 and iu21) is The eddy current flaw detection signal generated by eddy currents (for example, eddy currents iu11 and iu22) that increase and are aligned in the direction orthogonal to the scanning direction SC is suppressed. Therefore, the detection sensitivity of the eddy current flaw detection signal due to the longitudinal flaw is high, and the detection sensitivity of the eddy current flaw detection signal due to the orthogonal flaw is low.
In FIG. 1 (b3), when the directions of the excitation currents ie1 and ee2 are reversed, the directions of the eddy currents iu11 to iu22 are also reversed. Therefore, the detection sensitivity of the eddy current flaw detection signal due to the longitudinal flaw and the orthogonal flaw are caused. The relationship of the detection sensitivity of the eddy current flaw detection signal is the same as in the case of FIG. However, when one of the excitation currents ie1 and ee2 is reversed, the eddy current flaw detection signals generated by the eddy currents generated side by side in the direction parallel to the scanning direction SC are suppressed, and are aligned in the direction orthogonal to the scanning direction SC. The eddy current flaw detection signal generated by the generated eddy current increases.
図２は、渦電流探傷プローブの構造例を示す。
図２（ａ１），（ａ２），（ａ３）は、励磁素子が導電板からなる渦電流探傷プローブを、図２（ｂ１），（ｂ２）は、励磁素子が励磁コイルからなる渦電流探傷プローブを示す。
図２（ａ１），（ａ２），（ａ３）について、図２（ａ１）は、渦電流探傷プローブの平面図、図２（ａ２）は、図２（ａ１）のＡ部分の矢印方向の断面図、図２（ａ３）は、導電板の斜視図である。
導電板ＥＰ１、導電板ＥＰ２は、四角形の導電板からなり、両導電板の探傷面対向面は、互いに平行で、かつ探傷面と平行に配置してある。また検出コイルＤＣは、コイル面が導電板ＥＰ１，ＥＰ２の探傷面対向面と平行に、両探傷面対向面の略中央に配置してある。そして導電板ＥＰ１，ＥＰ２には、導電板ＥＰ１の探傷面対向面を流れる励磁電流ｉｅ１と導電板ＥＰ２の探傷面対向面を流れる励磁電流ｉｅ２が交差する方向へ流れるように、即ち両導電板の励磁電流方向が交差するように励磁電源ＲＶを接続してある。なお導電板ＥＰ１，ＥＰ２の間は、絶縁材等により絶縁してある。
FIG. 2 shows an example of the structure of an eddy current flaw detection probe.
2 (a1), (a2), and (a3) are eddy current flaw probes in which the excitation element is a conductive plate, and FIGS. 2 (b1) and (b2) are eddy current flaw probes in which the excitation element is an excitation coil. Indicates.
2 (a1), (a2), and (a3), FIG. 2 (a1) is a plan view of the eddy current flaw detection probe, and FIG. 2 (a2) is a cross-section in the direction of the arrow of portion A in FIG. 2 (a1). FIG. 2 and FIG. 2 (a3) are perspective views of the conductive plate.
The conductive plates EP1 and EP2 are made of rectangular conductive plates, and the flaw detection surface facing surfaces of both conductive plates are parallel to each other and arranged in parallel to the flaw detection surface. Further, the detection coil DC has a coil surface arranged in parallel with the flaw detection surface facing surfaces of the conductive plates EP1 and EP2 and substantially at the center of both flaw detection surface facing surfaces. In the conductive plates EP1 and EP2, the excitation current ie1 flowing through the surface facing the flaw detection surface of the conductive plate EP1 and the excitation current ie2 flowing through the surface facing the flaw detection surface of the conductive plate EP2 flow in a crossing direction. The excitation power supply RV is connected so that the excitation current directions intersect. The conductive plates EP1 and EP2 are insulated by an insulating material or the like.
導電板ＥＰ１，ＥＰ２は、長さＬ、幅Ｗ、厚さｔの四角形の板状体である。また導電板ＥＰ１，ＥＰ２は、長さＬで所定の厚さ（幅Ｗ方向の厚さ）の導体片（例えば銅の導体片）を複数個幅Ｗ方向へ積層し貼り合せて、板状体に形成してある。導電板ＥＰ１，ＥＰ２は、導体片を貼り合せない一枚板であってもよい。
図２（ａ１），（ａ２）の渦電流探傷プローブは、導電板ＥＰ１，ＥＰ２の探傷面対向面を被検査体Ｔの探傷面と平行に配置するから、薄く形成することができ、構造が簡単になる。
The conductive plates EP1 and EP2 are rectangular plate-like bodies having a length L, a width W, and a thickness t. The conductive plates EP1 and EP2 are formed by laminating and laminating a plurality of conductor pieces (for example, copper conductor pieces) having a length L and a predetermined thickness (thickness in the width W direction) in the width W direction. Is formed. The conductive plates EP1 and EP2 may be a single plate that does not bond the conductor pieces.
The eddy current flaw detection probe shown in FIGS. 2 (a1) and (a2) can be formed thin because the flaw detection surface facing surfaces of the conductive plates EP1 and EP2 are arranged in parallel with the flaw detection surface of the object T to be inspected. It will be easy.
図２（ｂ１），（ｂ２）について、図２（ｂ１）は、渦電流探傷プローブの平面図、図２（ｂ２）は、図２（ｂ１）のＢ部分の矢印方向の断面図である。
四角形の励磁コイルＥＣ１，ＥＣ２は、コイル軸が直交する（コイル面も直交する）ように配置し、四角形の検出コイルＤＣは、コイル軸が励磁コイルＥＣ１，ＥＣ２のコイル軸と直交し、励磁コイルＥＣ１，ＥＣ２の交差部と略対向する位置に配置してある。渦電流探傷プローブＰは、励磁コイルＥＣ１，ＥＣ２のコイル軸が探傷面に平行になり、検出コイルＤＣのコイル軸が被検査体Ｔの探傷面に垂直になるように設置して探傷する。
なお励磁コイルＥＣ１，ＥＣ２、検出コイルＤＣは、四角形に限らず、楕円形、円形等であってもよい。
2 (b1) and 2 (b2), FIG. 2 (b1) is a plan view of the eddy current flaw detection probe, and FIG. 2 (b2) is a cross-sectional view in the direction of the arrow of portion B in FIG. 2 (b1).
The square excitation coils EC1 and EC2 are arranged so that the coil axes are orthogonal (coil surfaces are also orthogonal), and the square detection coil DC is orthogonal to the coil axes of the excitation coils EC1 and EC2, and the excitation coil It is arranged at a position substantially opposite to the intersection of EC1 and EC2. The eddy current flaw detection probe P is installed and flawed so that the coil axes of the excitation coils EC1 and EC2 are parallel to the flaw detection surface and the coil axis of the detection coil DC is perpendicular to the flaw detection surface of the inspection object T.
The excitation coils EC1 and EC2 and the detection coil DC are not limited to a rectangle, but may be an ellipse or a circle.
図３（ａ）は、図１の渦電流探傷プローブを用いた渦電流探傷装置のブロック図、図３（ｂ）は、渦電流探傷プローブの走査方向を示す図である。
導電板ＥＰ１，ＥＰ２には、スイッチＳＷ１を介して励磁電源ＥＶが接続され、所定周波数の励磁電流が時分割で交互に供給される。導電板ＥＰ１，ＥＰ２のいずれかが励磁されているとき、検出コイルＤＣの検出電圧は、同期検波器ＤＥ１に供給される。また同期検波器ＤＥ１には、参照信号源ＲＶから励磁電流と同じ周波数の参照信号ＲＳ１が供給される。
FIG. 3A is a block diagram of an eddy current flaw detection apparatus using the eddy current flaw detection probe of FIG. 1, and FIG. 3B is a diagram showing a scanning direction of the eddy current flaw detection probe.
An excitation power supply EV is connected to the conductive plates EP1 and EP2 via a switch SW1, and an excitation current having a predetermined frequency is alternately supplied in a time division manner. When one of the conductive plates EP1 and EP2 is excited, the detection voltage of the detection coil DC is supplied to the synchronous detector DE1. Further, the reference signal RS1 having the same frequency as the exciting current is supplied from the reference signal source RV to the synchronous detector DE1.
スイッチＳＷ１が接点ａ１側へ切り替っているとき、即ち導電板ＥＰ１が励磁されているとき、スイッチＳＷ４は接点ｄ１側へ切り替る。そのとき同期検波器ＤＥ１の検波出力は、ローパスフィルタＬＰＦ１、ハイパスフィルタＨＰＦ１へ供給され、渦電流探傷信号Ｘ１が取り出される。スイッチＳＷ１が接点ａ２側へ切り替り、スイッチＳＷ４が接点ｄ２側へ切り替ると、同期検波器ＤＥ１の検波出力は、ローパスフィルタＬＰＦ２、ハイパスフィルタＨＰＦ２へ供給され、渦電流探傷信号Ｘ２が取り出される。渦電流探傷信号Ｘ１，Ｘ２は、夫々メモリＭＥ１１，ＭＥ２１に保存する。加算器ＡＤ１は、渦電流探傷信号Ｘ１，Ｘ２の和信号ＺＸを出力する。和信号ＺＸは、キズの評価に用いる。なお渦電流探傷信号Ｘ１，Ｘ２は、夫々和を取らずにキズの評価に用いることができる。 When the switch SW1 is switched to the contact a1 side, that is, when the conductive plate EP1 is excited, the switch SW4 is switched to the contact d1 side. At that time, the detection output of the synchronous detector DE1 is supplied to the low-pass filter LPF1 and the high-pass filter HPF1, and the eddy current flaw detection signal X1 is taken out. When the switch SW1 is switched to the contact a2 side and the switch SW4 is switched to the contact d2 side, the detection output of the synchronous detector DE1 is supplied to the low-pass filter LPF2 and the high-pass filter HPF2, and the eddy current flaw detection signal X2 is taken out. Eddy current flaw detection signals X1 and X2 are stored in the memories ME11 and ME21, respectively. The adder AD1 outputs a sum signal ZX of the eddy current flaw detection signals X1 and X2. The sum signal ZX is used for scratch evaluation. The eddy current flaw detection signals X1 and X2 can be used for scratch evaluation without taking the sum.
次に図３（ｂ）のように渦電流探傷プローブＰをＳＣ方向へ走査するとき、その走査方向ＳＣと平行な方向に進展する長手キズＦ１、走査方向ＳＣと直交する方向に進展する直交キズＦ２と渦電流探傷信号Ｘ１，Ｘ２の関係について説明する。
前述した図１の導電板ＥＰ１，ＥＰ２により発生する渦電流の説明から分かるように、渦電流探傷プローブＰが長手キズＦ１を通過するとき、導電板ＥＰ１の励磁中に得られた渦電流探傷信号Ｘ１と、導電板ＥＰ２の励磁中に得られた渦電流探傷信号Ｘ２は、位相が同じになる（ただし渦電流探傷プローブＰの交差部の中心ＰＣが長手キズＦ１を通過するときは、逆相となる）。一方渦電流探傷プローブＰが直交キズＦ２を通過するとき、導電板ＥＰ１の励磁中に得られた渦電流探傷信号Ｘ１と、導電板ＥＰ２の励磁中に得られた渦電流探傷信号Ｘ２は、位相が逆になる。したがって加算器ＡＤ１により、渦電流探傷信号Ｘ１と渦電流探傷信号Ｘ２の和を取ると、長手キズＦ１に起因する渦電流探傷信号Ｘ１と渦電流探傷信号Ｘ２は加わり合って増大するから加算信号ＺＹは増大するが、直交キズＦ２に起因する渦電流探傷信号Ｘ１と渦電流探傷信号Ｘ２は打ち消し合って抑制されるから加算信号ＺＹは小さくなる。
なお前記θが４５度の場合、渦電流探傷プローブＰの走査方向に平行する方向と直交する方向の間の方向に進展するキズは、その走査方向と０度〜±４５度の方向のキズに起因する渦電流探傷信号Ｘ１，Ｘ２は、同相になり、±４５度〜±９０度の方向のキズに起因する渦電流探傷信号Ｘ１，Ｘ２は、逆相になる。
Next, when the eddy current flaw detection probe P is scanned in the SC direction as shown in FIG. 3B, a longitudinal flaw F1 that develops in a direction parallel to the scanning direction SC and an orthogonal flaw that develops in a direction orthogonal to the scanning direction SC. The relationship between F2 and eddy current flaw detection signals X1 and X2 will be described.
As can be seen from the description of the eddy currents generated by the conductive plates EP1 and EP2 in FIG. 1, the eddy current flaw detection signal obtained during excitation of the conductive plate EP1 when the eddy current flaw probe P passes through the longitudinal flaw F1. X1 and the eddy current flaw detection signal X2 obtained during excitation of the conductive plate EP2 have the same phase (however, when the center PC at the intersection of the eddy current flaw probe P passes through the longitudinal flaw F1, the phase is reversed. Become). On the other hand, when the eddy current flaw probe P passes through the orthogonal flaw F2, the eddy current flaw detection signal X1 obtained during excitation of the conductive plate EP1 and the eddy current flaw detection signal X2 obtained during excitation of the conductive plate EP2 are in phase. Is reversed. Therefore, when the sum of the eddy current flaw detection signal X1 and the eddy current flaw detection signal X2 is obtained by the adder AD1, the eddy current flaw detection signal X1 and the eddy current flaw detection signal X2 due to the longitudinal flaw F1 are added and increased, so that the addition signal ZY However, since the eddy current flaw detection signal X1 and the eddy current flaw detection signal X2 caused by the orthogonal flaw F2 cancel each other and are suppressed, the addition signal ZY becomes small.
When the angle θ is 45 degrees, a scratch that develops in a direction between the direction parallel to the scanning direction of the eddy current flaw detection probe P is a scratch in the direction of 0 to ± 45 degrees with the scanning direction. The resulting eddy current flaw detection signals X1 and X2 are in phase, and the eddy current flaw detection signals X1 and X2 due to flaws in the direction of ± 45 degrees to ± 90 degrees are in reverse phase.
図３の渦電流探傷装置において、長手キズに起因する２つの渦電流探傷信号及び直交キズに起因する２つの渦電流探傷信号の位相関係は、前述したように、励磁電源ＥＶと導電板ＥＰ１、ＥＰ２の接続の仕方により変わるが、その位相関係を確認する必要のあるときは、例えば、被検査体に人工的にキズを形成し、そのキズの長手方向と直交する方向へ渦電流探傷プローブＰを走査し、そのとき得られた渦電流探傷信号Ｘ１，Ｘ２の位相から確認できる。その場合渦電流探傷プローブＰは、そのキズの長手方向と平行する方向へ走査してもよい。
なお図３の渦電流探傷装置は、1個の渦電流探傷プローブＰを用いているが、複数個の渦電流探傷プローブＰを千鳥状に配置すれば、広い範囲のキズを漏れなく探傷できる。
In the eddy current flaw detector shown in FIG. 3, the phase relationship between the two eddy current flaw detection signals caused by longitudinal flaws and the two eddy current flaw detection signals caused by orthogonal flaws is, as described above, the excitation power supply EV and the conductive plate EP1, Although it depends on how EP2 is connected, when it is necessary to confirm the phase relationship, for example, an artificial flaw is formed in the object to be inspected, and an eddy current flaw probe P is formed in a direction perpendicular to the longitudinal direction of the flaw. Can be confirmed from the phase of the eddy current flaw detection signals X1 and X2 obtained at that time. In that case, the eddy current flaw detection probe P may scan in a direction parallel to the longitudinal direction of the scratch.
The eddy current flaw detection apparatus shown in FIG. 3 uses one eddy current flaw detection probe P. However, if a plurality of eddy current flaw detection probes P are arranged in a staggered manner, a wide range of flaws can be flawlessly detected.
次に図４の渦電流探傷装置について説明する。
図４は、図１の渦電流探傷プローブを用いた渦電流探傷装置のブロック図で、位相が励磁電流と同じ参照信号と位相が励磁電流と９０度異なる参照信号を用いている。基本的構成は、図３の渦電流探傷装置と同じである。
導電板ＥＰ１，ＥＰ２には、励磁電源ＥＶから所定周波数の励磁電流がスイッチＳＷ１を介して交互に供給される。検出コイルＤＣの検出電圧は、スイッチＳＷ１が接点ａ１側へ切り替り、スイッチＳＷ２が接点ｂ１側へ切り替っているとき、同期検波器ＤＥ１１，ＤＥ１２に供給され、スイッチＳＷ１が接点ａ２側へ切り替り、スイッチＳＷ２が接点ｂ２側へ切り替っているとき、同期検波器ＤＥ２１，ＤＥ２２に供給される。また同期検波器ＤＥ１１〜ＤＥ２２には、参照信号源ＲＶから励磁電源ＥＶの周波数（励磁電流の周波数）と同じ周波数の第1参照信号ＲＳ１、第２参照信号ＲＳ２が供給される。参照信号ＲＳ１は、励磁電流と同じ位相であるが、参照信号ＲＳ２は、移相回路ＰＳにより９０度移相してある。即ち同期検波器ＤＥ１１〜ＤＥ２２には、周波数及び位相が励磁電流と同じ第1参照信号ＲＳ1（位相０度）と、周波数が励磁電流と同じで位相が９０度異なる（位相９０度の）第２参照信号ＲＳ２が供給される。スイッチＳＷ１，ＳＷ２は、時分割で切替えることができる。
Next, the eddy current flaw detector shown in FIG. 4 will be described.
FIG. 4 is a block diagram of an eddy current flaw detection apparatus using the eddy current flaw detection probe of FIG. 1, and uses a reference signal having the same phase as the excitation current and a reference signal having a phase different from the excitation current by 90 degrees. The basic configuration is the same as that of the eddy current flaw detector shown in FIG.
An excitation current having a predetermined frequency is alternately supplied from the excitation power supply EV to the conductive plates EP1 and EP2 via the switch SW1. The detection voltage of the detection coil DC is supplied to the synchronous detectors DE11 and DE12 when the switch SW1 is switched to the contact a1 side and the switch SW2 is switched to the contact b1 side, and the switch SW1 is switched to the contact a2 side. When the switch SW2 is switched to the contact b2 side, it is supplied to the synchronous detectors DE21 and DE22. The synchronous detectors DE11 to DE22 are supplied with the first reference signal RS1 and the second reference signal RS2 having the same frequency as the frequency of the excitation power supply EV (excitation current frequency) from the reference signal source RV. The reference signal RS1 has the same phase as the excitation current, but the reference signal RS2 is shifted by 90 degrees by the phase shift circuit PS. That is, the synchronous detectors DE11 to DE22 include a first reference signal RS1 (phase 0 degree) having the same frequency and phase as the excitation current, and a second signal having the same frequency as the excitation current and a phase different by 90 degrees (with a phase of 90 degrees). A reference signal RS2 is supplied. The switches SW1 and SW2 can be switched in a time division manner.
同期検波器ＤＥ１１〜ＤＥ２２は、検出コイルＤＣの検出電圧を参照信号ＲＳ１又は参照信号ＲＳ２により同期検波する。その検波出力は、ローパスフィルタＬＰＦ１１〜ＬＰＦ２２、ハイパスフィルタＨＰＦ１１〜ＨＰＦ２２に供給され、渦電流探傷信号Ｘ１，Ｘ２，Ｙ１，Ｙ２が取り出される。渦電流探傷信号Ｘ１，Ｘ２，Ｙ１，Ｙ２は、夫々メモリＭＥ１１〜ＭＥ２２に保存する。 The synchronous detectors DE11 to DE22 synchronously detect the detection voltage of the detection coil DC using the reference signal RS1 or the reference signal RS2. The detection output is supplied to low-pass filters LPF11 to LPF22 and high-pass filters HPF11 to HPF22, and eddy current flaw detection signals X1, X2, Y1, and Y2 are taken out. Eddy current flaw detection signals X1, X2, Y1, and Y2 are stored in memories ME11 to ME22, respectively.
渦電流探傷信号Ｘ１，Ｙ１は、導電板ＥＰ１に励磁電流が流れているとき、即ち導電板ＥＰ１の励磁中に検出された検出電圧（第１検出電圧）を、夫々参照信号ＲＳ１又は参照信号ＲＳ２により同期検波して得られた渦電流探傷信号であり、渦電流探傷信号Ｘ２，Ｙ２は、導電板ＥＰ２に励磁電流が供給されているとき、即ち導電板ＥＰ２の励磁中に検出された検出電圧（第２検出電圧）を、夫々参照信号ＲＳ１又は参照信号ＲＳ２により同期検波して得られた渦電流探傷信号である。また渦電流探傷信号Ｘ１，Ｘ２は、導電板ＥＰ１又は導電板ＥＰ２の励磁中に検出された検出電圧（第１検出電圧又は第２検出電圧）を、参照信号ＲＳ１により同期検波して得られた渦電流探傷信号であり、渦電流探傷信号Ｙ１，Ｙ２は、導電板ＥＰ１又は導電板ＥＰ２の励磁中に検出された検出電圧（第１検出電圧又は第２検出電圧）を、参照信号ＲＳ２により同期検波して得られた渦電流探傷信号である。
加算器ＡＤ１は、メモリＭＥ１２，ＭＥ２２の渦電流探傷信号Ｙ１，Ｙ２の和を取って和信号ＺＹを、また加算器ＡＤ２は、メモリＭＥ１１，ＭＥ２１の渦電流探傷信号Ｘ１，Ｘ２の和を取って和信号ＺＸを出力する。
The eddy current flaw detection signals X1 and Y1 are the detection voltage (first detection voltage) detected when the excitation current flows through the conductive plate EP1, that is, during the excitation of the conductive plate EP1, respectively, as the reference signal RS1 or the reference signal RS2. The eddy current flaw detection signals X2 and Y2 obtained by synchronous detection by the eddy current flaw detection signals X2 and Y2 are detected voltages detected when the excitation current is supplied to the conductive plate EP2, that is, during the excitation of the conductive plate EP2. (Second detection voltage) is an eddy current flaw detection signal obtained by synchronous detection with the reference signal RS1 or the reference signal RS2, respectively. Further, the eddy current flaw detection signals X1 and X2 are obtained by synchronously detecting the detection voltage (first detection voltage or second detection voltage) detected during excitation of the conductive plate EP1 or the conductive plate EP2 by the reference signal RS1. This is an eddy current flaw detection signal, and the eddy current flaw detection signals Y1 and Y2 synchronize the detection voltage (first detection voltage or second detection voltage) detected during excitation of the conductive plate EP1 or the conductive plate EP2 with the reference signal RS2. This is an eddy current flaw detection signal obtained by detection.
The adder AD1 calculates the sum of the eddy current flaw detection signals Y1 and Y2 of the memories ME12 and ME22, and the adder AD2 calculates the sum of the eddy current flaw detection signals X1 and X2 of the memories ME11 and ME21. The sum signal ZX is output.
和信号ＺＸは、長手キズの場合、渦電流探傷信号Ｘ１，Ｘ２が加わり合って増大し、直交キズの場合、渦電流探傷信号Ｘ１，Ｘ２が打消し合って抑制される。和信号ＺＹも同様に、長手キズの場合、渦電流探傷信号Ｙ１，Ｙ２が加わり合って増大し、直交キズの場合、渦電流探傷信号Ｙ１，Ｙ２が打消し合って抑制される。
キズの評価は、加算器ＡＤ１の和信号ＺＹと加算器ＡＤ２の和信号ＺＸを演算器（図示せず）で演算して行う。またキズの評価は、渦電流探傷信号Ｘ１，Ｘ２，Ｙ１，Ｙ２を演算器で演算して行うこともできる。
以上は、加算器ＡＤ１により渦電流探傷信号Ｙ１，Ｙ２の和を取り、加算器ＡＤ２により渦電流探傷信号Ｘ１，Ｘ２の和を取る例であるが、差を取ることもできる。その場合、長手キズに起因する差信号ＺＹ、差信号ＺＸは抑制され、直交キズに起因する差信号ＺＹ、差信号ＺＸは増大する。
In the case of a longitudinal flaw, the sum signal ZX increases with the addition of eddy current flaw detection signals X1 and X2, and in the case of an orthogonal flaw, the eddy current flaw detection signals X1 and X2 cancel each other and are suppressed. Similarly, in the case of a longitudinal flaw, the sum signal ZY increases with the addition of eddy current flaw detection signals Y1 and Y2, and in the case of a quadrature flaw, the eddy current flaw detection signals Y1 and Y2 cancel each other and are suppressed.
Scratch evaluation is performed by calculating the sum signal ZY of the adder AD1 and the sum signal ZX of the adder AD2 with an arithmetic unit (not shown). Scratch evaluation can also be performed by calculating eddy current flaw detection signals X1, X2, Y1, and Y2 with a calculator.
The above is an example in which the adder AD1 takes the sum of the eddy current flaw detection signals Y1 and Y2, and the adder AD2 takes the sum of the eddy current flaw detection signals X1 and X2, but a difference can also be taken. In this case, the difference signal ZY and the difference signal ZX caused by the longitudinal flaw are suppressed, and the difference signal ZY and the difference signal ZX caused by the orthogonal flaw are increased.
なお図４において、スイッチＳＷ１を接点ａ１側へ切り替えた状態で第１回目の探傷を行って渦電流探傷信号Ｘ１，Ｙ１を取得し、次に接点ａ２側へ切り替えた状態で第２回目の探傷を行って渦電流探傷信号Ｘ２，Ｙ２を取得することもできる。その場合、スイッチＳＷ２は省略して検出コイルＤＣを同期検波器ＤＥ１１，ＤＥ１２に直接接続し、ハイパスフィルタＨＰＦ１１，ＨＰＦ１２の夫々の出力にスイッチＳＷ１と同様のスイッチを接続して、ハイパスフィルタＨＰＦ１１，ＨＰＦ１２の出力から渦電流探傷信号Ｘ１，Ｙ１を取り出してメモリ等（例えばメモリＭＥ１１，ＭＥ１２）に保存し、その後ハイパスフィルタＨＰＦ１１，ＨＰＦ１２の出力から渦電流探傷信号Ｘ２，Ｙ２を取り出してメモリ等（例えばメモリＭＥ２１，ＭＥ２２）に保存するように構成することもできる。その場合には、同じ箇所を複数回走査する必要があるが同期検波器ＤＥ２１〜ハイパスフィルタＨＰＦ２１、同期検波器ＤＥ２２〜ハイパスフィルタＨＰＦ２２を省略できる。 In FIG. 4, the first flaw detection is performed with the switch SW1 switched to the contact a1 side to obtain the eddy current flaw detection signals X1 and Y1, and then the second flaw detection is performed with the switch SW1 switched to the contact a2 side. To obtain eddy current flaw detection signals X2 and Y2. In that case, the switch SW2 is omitted, and the detection coil DC is directly connected to the synchronous detectors DE11 and DE12. The same switches as the switch SW1 are connected to the outputs of the highpass filters HPF11 and HPF12, respectively, and the highpass filters HPF11 and HPF12 are connected. Eddy current flaw detection signals X1 and Y1 are taken out from the output of the output and stored in a memory or the like (for example, the memories ME11 and ME12), and then the eddy current flaw detection signals X2 and Y2 are taken out from the outputs of the high pass filters HPF11 and HPF12. It can also be configured to store in ME21, ME22). In this case, it is necessary to scan the same portion a plurality of times, but the synchronous detector DE21 to high-pass filter HPF21 and the synchronous detector DE22 to high-pass filter HPF22 can be omitted.
図５は、図４の渦電流探傷装置の変形例で、図４の４個の同期検波器を1個にし、１個の同期検波器ＤＥ１２を時分割で使用する例である。
スイッチＳＷ１を接点ａ１側へ、スイッチＳＷ５１，ＳＷ５２を接点ｅ１，ｆ１側へ切替える。その間にスイッチＳＷ３、ＳＷ４を接点ｃ１、ｄ１へ切替えて渦電流探傷信号Ｘ１を取り出し、メモリＭＥ１１に保存する。次にスイッチＳＷ３，ＳＷ４を接点ｃ２，ｄ２側へ切替えて渦電流探傷信号Ｙ１を取り出し、メモリＭＥ１２に保存する。
次にスイッチＳＷ１を接点ａ２側へ、スイッチＳＷ５１，ＳＷ５２を接点ｅ２，ｆ２側へ切替える。その間に、スイッチＳＷ３，ＳＷ４を接点ｃ１，ｄ１側へ切替えて渦電流探傷信号Ｘ２を取り出し、メモリＭＥ２２に保存する。次にスイッチＳＷ３，ＳＷ４を接点ｃ２，ｄ２側へ切替えて渦電流探傷信号Ｙ２を取り出し、メモリＭＥ２１に保存する。
図２の渦電流探傷装置は、同期検波器が１個でよいから、構成が簡単になる。
FIG. 5 is a modification of the eddy current flaw detector shown in FIG. 4, and is an example in which the four synchronous detectors in FIG. 4 are combined into one and the single synchronous detector DE12 is used in a time division manner.
The switch SW1 is switched to the contact a1 side, and the switches SW51 and SW52 are switched to the contacts e1 and f1 side. In the meantime, the switches SW3 and SW4 are switched to the contacts c1 and d1, and the eddy current flaw detection signal X1 is taken out and stored in the memory ME11. Next, the switches SW3 and SW4 are switched to the contact points c2 and d2 to take out the eddy current flaw detection signal Y1 and store it in the memory ME12.
Next, the switch SW1 is switched to the contact a2 side, and the switches SW51 and SW52 are switched to the contacts e2 and f2 side. In the meantime, the switches SW3 and SW4 are switched to the contacts c1 and d1 side to take out the eddy current flaw detection signal X2 and store it in the memory ME22. Next, the switches SW3 and SW4 are switched to the contact points c2 and d2 to take out the eddy current flaw detection signal Y2 and store it in the memory ME21.
The eddy current flaw detector shown in FIG. 2 has a simple configuration because only one synchronous detector is required.
ここで図６、図７により、図４の渦電流探傷装置の探傷試験の結果について説明する。
探傷試験は、渦電流探傷プローブＰをＳＣ方向へ走査して渦電流探傷信号Ｙ１，Ｙ２を取得した。図６、図７は、取得した渦電流探傷信号Ｙ１，Ｙ２の波形を示す。
試験に用いた渦電流探傷プローブＰの導電板ＥＰ１、ＥＰ２のサイズは、図２（ａ３）において、厚さｔ＝１ｍｍ、長さＬ＝幅ｗ＝１２ｍｍ、導体片の厚さ＝０．２ｍｍである。また被試験体は、長さ２０ｍｍのＳＳ４００の鋼板に深さ０．５ｍｍの放電加工キズを形成したものを用いた。励磁電流と参照信号の周波数は、３６ｋＨｚで、参照信号は、位相が励磁電流と９０度異なる参照信号を用いた。また渦電流探傷プローブＰは、リフトオフ１ｍｍで走査した。
Here, the result of the flaw detection test of the eddy current flaw detector shown in FIG. 4 will be described with reference to FIGS.
In the flaw detection test, eddy current flaw detection signals Y1 and Y2 were obtained by scanning the eddy current flaw detection probe P in the SC direction. 6 and 7 show waveforms of the acquired eddy current flaw detection signals Y1 and Y2.
The sizes of the conductive plates EP1 and EP2 of the eddy current testing probe P used in the test are as follows: thickness t = 1 mm, length L = width w = 12 mm, conductor piece thickness = 0.2 mm in FIG. It is. Further, the test object used was an SS400 steel plate having a length of 20 mm formed with an electric discharge machining scratch having a depth of 0.5 mm. The frequency of the excitation current and the reference signal was 36 kHz, and the reference signal used was a reference signal whose phase was 90 degrees different from the excitation current. The eddy current flaw detection probe P was scanned with a lift-off of 1 mm.
図６、図７において、縦軸は、渦電流探傷信号Ｙ１，Ｙ２（Ｙと表示）の振幅の最大値（Ｖ）を、横軸は、渦電流探傷プローブＰの走査時間（ｓ）を表している。
図６は、長手キズに起因する渦電流探傷信号Ｙ１，Ｙ２の波形で、図６（ａ）は、導電板ＥＰ１の励磁中に得られた渦電流探傷信号Ｙ１、図６（ｂ）は、導電板ＥＰ２の励磁中に得られた渦電流探傷信号Ｙ２、図６（ｃ）は、渦電流探傷信号Ｙ１，Ｙ２の和信号の波形である。
図６（ａ），（ｂ）の波形は、位相が同じであるから、渦電流探傷信号Ｙ１，Ｙ２の和信号は、両渦電流探傷信号が加わり合って図６（ｃ）のように増大した波形になる。
6 and 7, the vertical axis represents the maximum amplitude (V) of the eddy current flaw detection signals Y1 and Y2 (indicated as Y), and the horizontal axis represents the scanning time (s) of the eddy current flaw detection probe P. ing.
FIG. 6 shows waveforms of eddy current flaw detection signals Y1 and Y2 caused by longitudinal flaws. FIG. 6A shows eddy current flaw detection signals Y1 obtained during excitation of the conductive plate EP1, and FIG. The eddy current flaw detection signal Y2 obtained during excitation of the conductive plate EP2 and FIG. 6C are waveforms of the sum signal of the eddy current flaw detection signals Y1 and Y2.
Since the waveforms in FIGS. 6A and 6B have the same phase, the sum signal of the eddy current flaw detection signals Y1 and Y2 increases as shown in FIG. It becomes the waveform.
図７は、直交キズに起因する渦電流探傷信号Ｙ１，Ｙ２の波形で、図７（ａ）は、導電板ＥＰ１の励磁中に得られた渦電流探傷信号Ｙ１、図７（ｂ）は、導電板ＥＰ２の励磁中に得られた渦電流探傷信号Ｙ２、図７（ｃ）は、渦電流探傷信号Ｙ１，Ｙ２の和信号の波形である。
図７（ａ），（ｂ）の波形は、位相が逆になるから、渦電流探傷信号Ｙ１，Ｙ２の和信号は、両渦電流探傷信号が打消し合って図７（ｃ）のように抑制された波形になる。
以上図６、図７から明らかなように、図４の渦電流探傷装置は、長手キズに起因する渦電流探傷信号を増大し、直交キズに起因する渦電流探傷信号を抑制するから、従来十分には検出できなかった長手キズを確実に検出することができる。
FIG. 7 shows waveforms of eddy current flaw detection signals Y1 and Y2 caused by orthogonal flaws. FIG. 7A shows eddy current flaw detection signals Y1 obtained during excitation of the conductive plate EP1, and FIG. The eddy current flaw detection signal Y2 obtained during excitation of the conductive plate EP2 and FIG. 7C are waveforms of the sum signal of the eddy current flaw detection signals Y1 and Y2.
Since the waveforms of FIGS. 7A and 7B are reversed in phase, the sum signal of the eddy current flaw detection signals Y1 and Y2 cancels both eddy current flaw detection signals as shown in FIG. 7C. It becomes a suppressed waveform.
As is apparent from FIGS. 6 and 7, the eddy current flaw detection apparatus of FIG. 4 increases the eddy current flaw detection signal due to the longitudinal flaw and suppresses the eddy current flaw detection signal due to the orthogonal flaw. It is possible to reliably detect longitudinal flaws that could not be detected.
ＡＤ１，ＡＤ２ 加算器
ＤＥ１，ＤＥ１１，ＤＥ１２，ＤＥ２１，ＤＥ２２ 同期検波器
ＤＣ 検出コイル
ＥＣ１，ＥＣ２ 励磁コイル
ＥＰ１，ＥＰ２ 導電板
ＥＶ 励磁電源
ＬＰＦ１，ＬＰＦ２，ＬＰＦ１１，ＬＰＦ１２，ＬＰＦ２１，ＬＰＦ２２ ローパスフィルタ
ＨＰＦ１，ＨＰＦ２，ＨＰＦ１１，ＨＰＦ１２，ＨＰＦ２１，ＨＰＦ２２ ハイパスフィルタ
ＭＥ１１，ＭＥ１２，ＭＥ２１，ＭＥ２２ メモリ
Ｐ 渦電流探傷プローブ
ＰＳ 移相器（９０度移相）
ＲＳ１，ＲＳ２ 参照信号
ＲＶ 参照信号源
Ｔ 被検査体
AD1, AD2 adder DE1, DE11, DE12, DE21, DE22 synchronous detector DC detection coil EC1, EC2 excitation coil EP1, EP2 conductive plate EV excitation power source LPF1, LPF2, LPF11, LPF12, LPF21, LPF22 low-pass filter HPF1, HPF2, HPF11, HPF12, HPF21, HPF22 High pass filters ME11, ME12, ME21, ME22 Memory P Eddy current testing probe PS Phase shifter (90 degree phase shift)
RS1, RS2 Reference signal RV Reference signal source T Inspected object
Claims (6)
２個の励磁素子を周波数及び位相が同じ励磁電流により交互に励磁し、一方及び他方の励磁素子の励磁中に検出素子に発生した検出電圧を励磁電流と同じ周波数の参照信号により同期検波し、２つの渦電流探傷信号を取り出してその２つの渦電流探傷信号の和信号又は差信号を発生し、その和信号又は差信号を用いてキズを評価することを特徴とする渦電流探傷方法。 Consisting of two excitation elements and one detection element, the excitation elements are composed of conductive plates, and the two conductive plates are parallel to the flaw detection surface and the direction of the excitation current on the flaw detection surface opposite surface Are arranged so as to intersect and ± θ with respect to the center line in the scanning direction, or the excitation element is a coil, and the two coils have a coil axis parallel to the flaw detection surface and the coil axes intersect. In the eddy current flaw detection probe arranged so as to be ± θ with respect to the center line in the scanning direction, or in the eddy current flaw detection probe, the θ is 45 degrees using an eddy current flaw detection probe,
Two excitation elements are excited alternately by the excitation current having the same frequency and phase, and the detection voltage generated in the detection element during excitation of one and the other excitation element is synchronously detected by a reference signal having the same frequency as the excitation current, An eddy current flaw detection method comprising: extracting two eddy current flaw detection signals, generating a sum signal or a difference signal of the two eddy current flaw detection signals, and evaluating a scratch using the sum signal or difference signal.
２個の励磁素子を周波数及び位相が同じ励磁電流により交互に励磁し、一方及び他方の励磁素子の励磁中に検出素子に発生した検出電圧を励磁電流と同じ周波数の参照信号により同期検波し、２つの渦電流探傷信号を取り出してその２つの渦電流探傷信号の和信号又は差信号を発生し、その和信号又は差信号を用いてキズを評価すると同時にその２つの渦電流探傷信号を用いてキズを評価することを特徴とする渦電流探傷方法。 Consisting of two excitation elements and one detection element, the excitation elements are composed of conductive plates, and the two conductive plates are parallel to the flaw detection surface and the direction of the excitation current on the flaw detection surface opposite surface Are arranged so as to intersect and ± θ with respect to the center line in the scanning direction, or the excitation element is a coil, and the two coils have a coil axis parallel to the flaw detection surface and the coil axes intersect. In the eddy current flaw detection probe arranged so as to be ± θ with respect to the center line in the scanning direction, or in the eddy current flaw detection probe, the θ is 45 degrees using an eddy current flaw detection probe,
Two excitation elements are excited alternately by the excitation current having the same frequency and phase, and the detection voltage generated in the detection element during excitation of one and the other excitation element is synchronously detected by a reference signal having the same frequency as the excitation current, Two eddy current flaw detection signals are taken out, a sum signal or a difference signal of the two eddy current flaw detection signals is generated, and scratches are evaluated using the sum signal or difference signal, and at the same time, the two eddy current flaw detection signals are used. An eddy current flaw detection method characterized by evaluating scratches.
２個の励磁素子に周波数及び位相が同じ励磁電流を交互に供給する励磁電源、励磁電流と同じ周波数の参照信号を供給する参照信号源、一方及び他方の励磁素子の励磁中に、検出素子に発生した検出電圧を参照信号により同期検波する同期検波器、同期検波器の出力から２つの渦電流探傷信号を取り出してその２つの渦電流探傷信号の和信号又は差信号を発生する手段、その和信号又は差信号を用いてキズを評価する手段を備えていることを特徴とする渦電流探傷装置。 Consisting of two excitation elements and one detection element, the excitation elements are composed of conductive plates, and the two conductive plates are parallel to the flaw detection surface and the direction of the excitation current on the flaw detection surface opposite surface Are arranged so as to intersect and ± θ with respect to the center line in the scanning direction, or the excitation element is a coil, and the two coils have a coil axis parallel to the flaw detection surface and the coil axes intersect. In the eddy current flaw detection probe arranged so as to be ± θ with respect to the center line in the scanning direction, or in the eddy current flaw detection probe, the θ is an eddy current flaw detection probe of 45 degrees ,
An excitation power supply that alternately supplies excitation currents having the same frequency and phase to the two excitation elements, a reference signal source that supplies a reference signal having the same frequency as the excitation current, and a detection element during excitation of one and the other excitation elements A synchronous detector for synchronously detecting the generated detection voltage with a reference signal, means for taking out two eddy current flaw detection signals from the output of the synchronous detector and generating a sum signal or a difference signal of the two eddy current flaw detection signals, and the sum An eddy current flaw detector comprising a means for evaluating a scratch using a signal or a difference signal.
２個の励磁素子に周波数及び位相が同じ励磁電流を交互に供給する励磁電源、励磁電流と同じ周波数の参照信号を供給する参照信号源、一方及び他方の励磁素子の励磁中に、検出素子に発生した検出電圧を参照信号により同期検波する同期検波器、同期検波器の出力から２つの渦電流探傷信号を取り出してその２つの渦電流探傷信号の和信号又は差信号を発生する手段、その和信号又は差信号を用いてキズを評価すると同時にその２つの渦電流探傷信号を用いてキズを評価する手段を備えていることを特徴とする渦電流探傷装置。 Consisting of two excitation elements and one detection element, the excitation elements are composed of conductive plates, and the two conductive plates are parallel to the flaw detection surface and the direction of the excitation current on the flaw detection surface opposite surface Are arranged so as to intersect and ± θ with respect to the center line in the scanning direction, or the excitation element is a coil, and the two coils have a coil axis parallel to the flaw detection surface and the coil axes intersect. In the eddy current flaw detection probe arranged so as to be ± θ with respect to the center line in the scanning direction, or in the eddy current flaw detection probe, the θ is an eddy current flaw detection probe of 45 degrees ,
An excitation power supply that alternately supplies excitation currents having the same frequency and phase to the two excitation elements, a reference signal source that supplies a reference signal having the same frequency as the excitation current, and a detection element during excitation of one and the other excitation elements A synchronous detector for synchronously detecting the generated detection voltage with a reference signal, means for taking out two eddy current flaw detection signals from the output of the synchronous detector and generating a sum signal or a difference signal of the two eddy current flaw detection signals, and the sum An eddy current flaw detector comprising a means for evaluating flaws using a signal or a difference signal and simultaneously evaluating flaws using the two eddy current flaw detection signals.
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