JPH08313493A - Eddy current test equipment - Google Patents
Eddy current test equipmentInfo
- Publication number
- JPH08313493A JPH08313493A JP11822695A JP11822695A JPH08313493A JP H08313493 A JPH08313493 A JP H08313493A JP 11822695 A JP11822695 A JP 11822695A JP 11822695 A JP11822695 A JP 11822695A JP H08313493 A JPH08313493 A JP H08313493A
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- Japan
- Prior art keywords
- circuit
- signal
- output
- phase
- frequency
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は渦流探傷装置に関し、
特に、金属の板やパイプや線材などの金属の傷の探傷検
査に用いるような渦流探傷装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eddy current flaw detector,
In particular, the present invention relates to an eddy current flaw detection device used for flaw detection inspection of metal flaws such as metal plates, pipes and wires.
【０００２】[0002]
【従来の技術】金属の表面の傷を検査するために、渦流
探傷装置が用いられている。図６はそのような従来の渦
流探傷装置の概略ブロック図である。図６において、発
振回路１は一定の周波数のｓｉｎ波の発振信号を発生
し、増幅回路２と位相回路５とに与える。増幅回路２は
発振信号を増幅し、バランス回路３を励磁する。バラン
ス回路３はコイルＬ１とＬ２と図示しない２つの抵抗と
によって平衡回路を構成しており、コイルＬ１，Ｌ２を
検査対象に近接させたとき、常時は平衡状態を保ってい
る。そして、コイルＬ１，Ｌ２を検査対象に沿って移動
させ、検査対象の表面に傷があるとき、コイルＬ１，Ｌ
２のインピーダンスが変化することにより平衡状態がく
ずれて、励磁信号の周波数と同一の周波数でかつ励磁信
号に対して所定の位相差を有し、振幅が変動した信号と
して出力される。この信号は増幅回路４に与えられて増
幅される。2. Description of the Related Art An eddy current flaw detector is used to inspect a metal surface for flaws. FIG. 6 is a schematic block diagram of such a conventional eddy current flaw detector. In FIG. 6, the oscillator circuit 1 generates a sin wave oscillation signal having a constant frequency and supplies it to the amplifier circuit 2 and the phase circuit 5. The amplifier circuit 2 amplifies the oscillation signal and excites the balance circuit 3. The balance circuit 3 constitutes a balanced circuit by the coils L1 and L2 and two resistors (not shown), and always maintains the balanced state when the coils L1 and L2 are brought close to the inspection object. Then, the coils L1 and L2 are moved along the inspection target, and when the surface of the inspection target is scratched, the coils L1 and L2 are
When the impedance of 2 changes, the equilibrium state collapses, and the signal is output as a signal having the same frequency as the excitation signal, a predetermined phase difference with respect to the excitation signal, and varying amplitude. This signal is given to the amplifier circuit 4 and amplified.
【０００３】一方、発振回路１から出力された発振信号
は位相回路５に与えられて、その位相が０〜３６０°の
いずれかに設定される。この０〜３６０°の位相設定
は、後述の位相検波回路７の出力で検出出力条件を検出
するため、位相検波特性がｃｏｓθの出力条件で働くよ
うに、位相特性を設定するためである。さらに、位相分
配回路６によって励磁信号と同じ位相の信号と、例示信
号と９０度位相のずれた信号とに分配される。位相検波
回路７は励磁信号と同じ位相の信号によってバランス回
路３の出力を同期検波してコイルＬ１，Ｌ２の抵抗成分
を示すＸ軸信号を出力する。また、位相検波回路８は励
磁信号に対して９０度位相のずれた信号によってバラン
ス回路３の出力を同期検波してコイルＬ１，Ｌ２のイン
ダクタンス成分を示すＹ軸信号を出力する。Ｘ軸信号お
よびＹ軸信号は、それぞれバンドパスフィルタ９，１０
に入力されて、ｓｉｎ波成分が除去されて出力される。On the other hand, the oscillation signal output from the oscillation circuit 1 is given to the phase circuit 5 and its phase is set to any of 0 to 360 °. The phase setting of 0 to 360 ° is for setting the phase characteristic so that the phase detection characteristic works under the output condition of cos θ because the detection output condition is detected by the output of the phase detection circuit 7 described later. Further, the phase distribution circuit 6 distributes the signal having the same phase as the excitation signal, and the exemplary signal and the signal whose phase is shifted by 90 degrees. The phase detection circuit 7 synchronously detects the output of the balance circuit 3 with a signal having the same phase as the excitation signal and outputs an X-axis signal indicating the resistance component of the coils L1 and L2. The phase detection circuit 8 synchronously detects the output of the balance circuit 3 with a signal whose phase is shifted by 90 degrees with respect to the excitation signal, and outputs a Y-axis signal indicating the inductance components of the coils L1 and L2. The X-axis signal and the Y-axis signal are the band pass filters 9 and 10, respectively.
Is input to, and the sine wave component is removed and output.
【０００４】これらのＸ軸信号とＹ軸信号をオシロスコ
ープに入力すると、図７に示すようなリサージュ波形が
得られる。また、図８は出力チャート波形である。When these X-axis signal and Y-axis signal are input to the oscilloscope, a Lissajous waveform as shown in FIG. 7 is obtained. Further, FIG. 8 is an output chart waveform.
【０００５】[0005]
【発明が解決しようとする課題】図７（ａ）に示すよう
に、検査対象に傷があると、Ｘ軸，Ｙ軸に対して位相を
有するように信号成分Ｓが表示され、この信号によって
傷の存在することが判別できる。このとき、オシロスコ
ープには、リサージュ波形としてノイズ成分Ｎも同時に
表示される。図７（ａ）に示すように、信号成分Ｓとノ
イズ成分Ｎの周波数に差があれば、図８に示す出力チャ
ート波形により、信号成分Ｓをレベル弁別できるが、信
号成分Ｓとノイズ成分Ｎの位相ベクトル方向の差が同じ
であれば、Ｓ／Ｎ比が低いため、図７（ｂ）に示すよう
に両者の区別をすることができないという欠点があっ
た。As shown in FIG. 7 (a), when the inspection object has a flaw, the signal component S is displayed so as to have a phase with respect to the X axis and the Y axis. The presence of scratches can be determined. At this time, the noise component N is simultaneously displayed as a Lissajous waveform on the oscilloscope. As shown in FIG. 7A, if there is a difference between the frequencies of the signal component S and the noise component N, the signal component S can be level discriminated by the output chart waveform shown in FIG. If the difference in the direction of the phase vector is the same, the S / N ratio is low, so that there is a drawback that the two cannot be distinguished as shown in FIG. 7B.
【０００６】それゆえに、この発明の主たる目的は、ノ
イズ成分と信号成分の区別を容易にできるようにＳ／Ｎ
比の向上した渦流探傷装置を提供することである。Therefore, the main object of the present invention is to make it possible to easily distinguish between noise components and signal components by S / N.
An object of the present invention is to provide an eddy current flaw detection device having an improved ratio.
【０００７】[0007]
【課題を解決するための手段】この発明は固定周波数の
信号を増幅してコイルに供給し、コイルと検査対象とを
相対的に移動させ、検査対象となる金属表面の傷に応じ
て周波数と電圧とが変化した信号を同期検波して出力す
る渦流探傷装置であって、同期検波出力に含まれるコイ
ル自身の抵抗成分を示す信号の振幅を２乗しかつその周
波数成分を２倍にする第１の２乗回路と、同期検波出力
に含まれるコイル自身のインダクタンス成分を示す信号
の振幅を２乗しかつその周波数成分を２倍にする第２の
２乗回路と、第１の２乗回路の出力に含まれる２倍の周
波数成分を抽出する第１のフィルタ回路と、第２の２乗
回路の出力に含まれる２倍の周波数成分を抽出する第２
のフィルタ回路と、第１および第２のフィルタ回路の出
力の位相差を出力する位相回路と、位相回路のそれぞれ
の出力を直線にする非線形回路とを備えて構成される。According to the present invention, a signal of a fixed frequency is amplified and supplied to a coil, the coil and an inspection object are moved relatively to each other, and the frequency and the frequency are adjusted according to a scratch on a metal surface to be inspected. An eddy current flaw detector which synchronously detects and outputs a signal whose voltage has changed, wherein the amplitude of the signal indicating the resistance component of the coil itself included in the synchronous detection output is squared and its frequency component is doubled. 1 square circuit, a second square circuit that squares the amplitude of the signal indicating the inductance component of the coil itself included in the synchronous detection output, and doubles the frequency component, and a first square circuit A first filter circuit for extracting a double frequency component included in the output of the second and a second filter circuit for extracting a double frequency component included in the output of the second square circuit.
Of the first and second filter circuits, a phase circuit that outputs the phase difference between the outputs of the first and second filter circuits, and a non-linear circuit that linearizes the outputs of the phase circuits.
【０００８】[0008]
【作用】この発明にかかる渦流探傷装置は、同期検波出
力に含まれるコイル自身の抵抗成分を示す信号とインダ
クタンス成分を示す信号のそれぞれの振幅を２乗し、か
つそれぞれの周波数を２倍にして、それぞれの２倍の周
波数成分を抽出して位相差を出力することによって、ノ
イズ信号を平均的にでき、かつ位相差を２倍に拡大でき
るので、Ｓ／Ｎ比を５〜６程度まで向上でき、信号とノ
イズとの区別が容易になる。The eddy current flaw detector according to the present invention squares the amplitude of each of the signal indicating the resistance component and the signal indicating the inductance component of the coil itself included in the synchronous detection output, and doubles each frequency. , The noise signal can be averaged and the phase difference can be doubled by extracting the frequency difference of each of them and outputting the phase difference. Therefore, the S / N ratio is improved to about 5 to 6. This makes it easier to distinguish between signals and noise.
【０００９】[0009]
【実施例】図１はこの発明の一実施例のブロック図であ
る。図１において、図６に示した位相検波回路７，８の
それぞれの出力に２乗回路１１，１２が接続される。２
乗回路１１，１２はＸ軸信号およびＹ軸信号のそれぞれ
の電圧を２乗しかつ周波数を２倍にする。２乗回路１
１，１２の出力はフィルタ１３，１４に与えられ、それ
ぞれ２乗回路１１，１２で発生した２倍の周波数成分の
みを抽出して位相回路１５に与える。位相回路１５はＸ
軸およびＹ軸の座標軸を回転するものであって、出力Ｘ
として２Ｘ＋２Ｙ，出力Ｙとして２Ｘ−２Ｙの信号を対
数回路１６，１７に与える。対数回路１６，１７は２乗
回路１１，１２によって２乗された入力信号を補正す
る。なお、対数回路１６，１７に変えて平方根回路を用
いてもよい。1 is a block diagram of an embodiment of the present invention. In FIG. 1, squaring circuits 11 and 12 are connected to the outputs of the phase detection circuits 7 and 8 shown in FIG. 6, respectively. Two
The squaring circuits 11 and 12 square the respective voltages of the X-axis signal and the Y-axis signal and double the frequency. Square circuit 1
The outputs of 1 and 12 are given to filters 13 and 14, respectively, and only the double frequency components generated in the squaring circuits 11 and 12 are extracted and given to the phase circuit 15. Phase circuit 15 is X
Axis X and Y coordinate axes are rotated, and output X
2X + 2Y and 2X-2Y as output Y are given to the logarithmic circuits 16 and 17, respectively. The logarithmic circuits 16 and 17 correct the input signal squared by the squaring circuits 11 and 12. A square root circuit may be used instead of the logarithmic circuits 16 and 17.
【００１０】図２は図１に示した対数回路の入出力特性
を示す図であり、図３は２乗回路の特性を示す図であ
り、図４はこの発明の一実施例による信号成分Ｓとノイ
ズ成分Ｎのリサージュ波形と従来例によるリサージュ波
形とを対比して示す図であり、図５は発明の一実施例に
おける出力チャート波形を示す図である。FIG. 2 is a diagram showing input / output characteristics of the logarithmic circuit shown in FIG. 1, FIG. 3 is a diagram showing characteristics of a squaring circuit, and FIG. 4 is a signal component S according to an embodiment of the present invention. FIG. 6 is a diagram showing a Lissajous waveform of the noise component N and a Lissajous waveform according to a conventional example in comparison, and FIG. 5 is a diagram showing an output chart waveform in an embodiment of the invention.
【００１１】図１に示したように構成することによっ
て、位相検波回路７，８から出力されたＸ軸信号とＹ軸
信号は２乗回路１１，１２によって電圧が２乗されかつ
周波数が２倍され、フィルタ１３，１４によってＸ軸信
号とＹ軸信号に含まれる２倍の周波数成分のみが抽出さ
れ、位相回路１５によってＸ軸，Ｙ軸の座標が回転され
る。２乗回路１１，１２によって図３に示すように入力
が２乗されているので、図２に示す特性を有する対数回
路１６，１７によって直線にされる。With the configuration shown in FIG. 1, the voltage of the X-axis signal and the Y-axis signal output from the phase detection circuits 7 and 8 is squared by the squaring circuits 11 and 12, and the frequency is doubled. Then, only the double frequency components included in the X-axis signal and the Y-axis signal are extracted by the filters 13 and 14, and the X-axis and Y-axis coordinates are rotated by the phase circuit 15. Since the input is squared by the squaring circuits 11 and 12 as shown in FIG. 3, the input is squared by the logarithmic circuits 16 and 17 having the characteristics shown in FIG.
【００１２】したがって、この発明の一実施例によれ
ば、周波数が２倍になることによってノイズ成分が平均
的になり、図４（ａ）に示すように、Ｘ軸，Ｙ軸方向の
位相差が図４（ｂ）に示す従来例に比べて２倍に拡大さ
れ、図５に示すように、Ｓ／Ｎ比を４〜５倍にすること
ができるので、ノイズ成分Ｎと信号成分Ｓとのレベル弁
別を従来例に比べて改善できる。Therefore, according to one embodiment of the present invention, the noise component becomes averaged by doubling the frequency, and as shown in FIG. 4A, the phase difference in the X-axis and Y-axis directions is increased. Is doubled as compared with the conventional example shown in FIG. 4B, and the S / N ratio can be made 4 to 5 times as shown in FIG. 5, so that the noise component N and the signal component S are The level discrimination can be improved compared to the conventional example.
【００１３】[0013]
【発明の効果】以上のように、この発明によれば、同期
検波出力に含まれるコイル自身の抵抗成分を示す信号と
インダクタンス成分を示す信号のそれぞれの振幅を２乗
しかつそれぞれ周波数を２倍にし、２倍の周波数成分を
抽出して位相差を出力することによって、ノイズ信号を
平均的にすることができかつ位相差を２倍に拡大して、
Ｓ／Ｎ比を５〜６倍程度まで向上でき、信号成分とノイ
ズ成分との区別を容易にできる。As described above, according to the present invention, the amplitude of each of the signal indicating the resistance component of the coil itself and the signal indicating the inductance component included in the synchronous detection output is squared and the frequency is doubled. By extracting the frequency component of twice and outputting the phase difference, the noise signal can be averaged and the phase difference can be doubled.
The S / N ratio can be improved to about 5 to 6 times, and the signal component and the noise component can be easily distinguished.
【図１】この発明の一実施例の概略ブロック図である。FIG. 1 is a schematic block diagram of an embodiment of the present invention.
【図２】図１に示した対数回路の入出力特性を示す図で
ある。FIG. 2 is a diagram showing input / output characteristics of the logarithmic circuit shown in FIG.
【図３】２乗回路の特性を示す図である。FIG. 3 is a diagram showing characteristics of a squaring circuit.
【図４】この発明の一実施例による信号成分Ｓとノイズ
成分Ｎのリサージュ波形と従来例によるリサージュ波形
とを対比して示す図である。FIG. 4 is a diagram showing a Lissajous waveform of a signal component S and a noise component N according to an embodiment of the present invention in comparison with a Lissajous waveform according to a conventional example.
【図５】この発明の一実施例の出力チャート波形を示す
図である。FIG. 5 is a diagram showing an output chart waveform according to an embodiment of the present invention.
【図６】従来の渦流探傷装置の概略ブロック図である。FIG. 6 is a schematic block diagram of a conventional eddy current flaw detector.
【図７】図６に示した従来の渦流探傷装置におけるリサ
ージュ波形を示す図である。FIG. 7 is a diagram showing a Lissajous waveform in the conventional eddy current flaw detector shown in FIG.
【図８】図６に示した従来の渦流探傷装置の出力チャー
ト波形を示す図である。FIG. 8 is a diagram showing an output chart waveform of the conventional eddy current flaw detector shown in FIG.
７，８ 位相検波回路 １１，１２ ２乗回路 １３，１４ フィルタ １５ 位相回路 １６，１７ 対数回路 7,8 Phase detection circuit 11,12 Square circuit 13,14 Filter 15 Phase circuit 16,17 Logarithmic circuit
───────────────────────────────────────────────────── フロントページの続き (72)発明者 池永 昭夫 愛知県名古屋市東区東桜一丁目１番６号 住友電気工業株式会社中部支社内 (72)発明者 上野 明喜夫 兵庫県川西市下加茂１丁目15番７号 有限 会社日本エステック内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Ikenaga 1-6 Higashizakura Higashi-ku Nagoya City Aichi Prefecture Sumitomo Electric Industries, Ltd. Chubu Branch Office (72) Inventor Akio Ueno 1-chome Shimokamo, Kawanishi City, Hyogo Prefecture 15th-7th Japan STEC Co., Ltd.
Claims (2)
給し、前記コイルと検査対象とを相対的に移動させ、検
査対象となる金属表面の傷に応じて、周波数と電圧とが
変化した信号を同期検波して出力する渦流探傷装置にお
いて、 前記同期検波出力に含まれる前記コイル自身の抵抗成分
を示す信号の振幅を２乗しかつその周波数を２倍にする
第１の２乗回路、 前記同期検波出力に含まれる前記コイル自身のインダク
タンス成分を示す信号の振幅を２乗しかつその周波数を
２倍にする第２の２乗回路、 前記第１の２乗回路の出力に含まれる２倍の周波数成分
を抽出する第１のフィルタ回路、 前記第２の２乗回路の出力に含まれる２倍の周波数成分
を抽出する第２のフィルタ回路、 前記第１および第２のフィルタ回路の出力の位相差を出
力する位相回路、および前記位相回路のそれぞれの出力
を直線にする非線形回路を備えた、渦流探傷装置。1. A fixed-frequency signal is amplified and supplied to a coil, the coil and the inspection object are moved relatively, and the frequency and voltage are changed according to the scratch on the metal surface to be inspected. In an eddy current flaw detector that synchronously detects and outputs a signal, a first squaring circuit that squares the amplitude of a signal indicating the resistance component of the coil itself included in the synchronous detection output and doubles the frequency thereof, A second squaring circuit for squaring the amplitude of a signal indicating the inductance component of the coil itself included in the synchronous detection output and doubling its frequency; 2 included in the output of the first squaring circuit; A first filter circuit for extracting a double frequency component; a second filter circuit for extracting a double frequency component included in the output of the second squaring circuit; outputs of the first and second filter circuits Output the phase difference of Phase circuit, and having a non-linear circuit to a straight line the respective outputs of said phase circuit, eddy-current flaw detection device.
項１の渦流探傷装置。2. The eddy current flaw detector according to claim 1, wherein the non-linear circuit is a logarithmic circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11822695A JPH08313493A (en) | 1995-05-17 | 1995-05-17 | Eddy current test equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11822695A JPH08313493A (en) | 1995-05-17 | 1995-05-17 | Eddy current test equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH08313493A true JPH08313493A (en) | 1996-11-29 |
Family
ID=14731350
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11822695A Withdrawn JPH08313493A (en) | 1995-05-17 | 1995-05-17 | Eddy current test equipment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH08313493A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009019909A (en) * | 2007-07-10 | 2009-01-29 | Hitachi Ltd | Method and device for discriminating defect |
| JP2010276431A (en) * | 2009-05-27 | 2010-12-09 | Toyota Motor Corp | Eddy current flaw detector and eddy current flaw detection method |
-
1995
- 1995-05-17 JP JP11822695A patent/JPH08313493A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009019909A (en) * | 2007-07-10 | 2009-01-29 | Hitachi Ltd | Method and device for discriminating defect |
| JP2010276431A (en) * | 2009-05-27 | 2010-12-09 | Toyota Motor Corp | Eddy current flaw detector and eddy current flaw detection method |
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