JP2000046802A - Sensor head for eddy current flaw detection - Google Patents
Sensor head for eddy current flaw detectionInfo
- Publication number
- JP2000046802A JP2000046802A JP10210858A JP21085898A JP2000046802A JP 2000046802 A JP2000046802 A JP 2000046802A JP 10210858 A JP10210858 A JP 10210858A JP 21085898 A JP21085898 A JP 21085898A JP 2000046802 A JP2000046802 A JP 2000046802A
- Authority
- JP
- Japan
- Prior art keywords
- coil
- sensor head
- eddy current
- detection
- pulse
- 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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- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、例えば、保温材に
囲まれた配管の検査や渦流探傷や鉄筋コンクリート中の
鉄筋検出等に用いることの可能な渦流探傷用センサヘッ
ドに関するものである。さらに詳しくは、コアの中心軸
周りに巻回した検出コイル及び励磁コイルを前記コアの
周囲に設けた渦流探傷用センサヘッドに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor head for eddy current testing which can be used, for example, for inspection of pipes surrounded by a heat insulating material, eddy current testing, and detection of reinforcing bars in reinforced concrete. More specifically, the present invention relates to an eddy current flaw detection sensor head having a detection coil and an excitation coil wound around a central axis of a core provided around the core.
【０００２】[0002]
【従来の技術】従来より渦流探傷法の一つとして、パル
ス渦流探傷法が実施されている。このパルス渦流探傷法
では、大電流のパルスを励磁コイルに与えてもコイルは
発熱しにくいことから、小さなセンサヘッドに大電流の
励磁用パルスを付与して強力な磁束を利用した探傷試験
を行っている。2. Description of the Related Art A pulse eddy current flaw detection method has been conventionally used as one of eddy current flaw detection methods. In this pulse eddy current flaw detection method, since the coil does not easily generate heat even when a large current pulse is applied to the excitation coil, a flaw detection test using a strong magnetic flux by applying a large current excitation pulse to a small sensor head is performed. ing.
【０００３】ところで、例えば保温材に囲まれた配管の
検査やパルス渦流探傷や鉄筋コンクリート中の鉄筋検出
等、センサヘッドと配管や鉄筋等の被検体との間にリフ
トオフ（隔たり）が存在する場合がある。このような場
合、通常のパルス渦流探傷用センサヘッドを用いると、
リフトオフによって被検体が十分に励磁されずに傷等を
認識することができなかったり、磁束が周囲に拡散して
鉄筋検出の分解能が不十分となる等の問題があった。ま
た、通常の交流を用いた渦流探傷検査においても、さら
に磁束の拡散を防ぎ、検査精度を向上させることが望ま
れていた。By the way, there is a case where a lift-off (distance) exists between a sensor head and an object such as a pipe or a reinforcing bar, for example, for inspection of a pipe surrounded by a heat insulating material, pulse eddy current flaw detection, and detection of a reinforcing bar in reinforced concrete. is there. In such a case, if a normal pulse eddy current flaw detection sensor head is used,
There have been problems such as that the subject is not sufficiently excited due to the lift-off, so that it is not possible to recognize a flaw or the like, or that the magnetic flux is diffused around and the resolving power detection is insufficient. Also, in the eddy current inspection using a normal alternating current, it has been desired to further prevent the diffusion of the magnetic flux and improve the inspection accuracy.
【０００４】[0004]
【発明が解決しようとする課題】かかる従来の実状に鑑
みて、本発明は、従来より高精度で且つ分解能の高いパ
ルス渦流探傷検査や交流波を用いた渦流探傷検査を行う
ことの可能な渦流探傷用センサヘッドを提供することを
目的とする。SUMMARY OF THE INVENTION In view of such a conventional situation, the present invention provides an eddy current capable of performing pulse eddy current inspection with higher precision and higher resolution than conventional ones and eddy current inspection using an AC wave. An object of the present invention is to provide a flaw detection sensor head.
【０００５】[0005]
【課題を解決するための手段】上記目的を達成するた
め、本発明に係る渦流探傷用センサヘッドの特徴は、コ
アの中心軸周りに巻回した検出コイル及び励磁コイルを
前記コアの周囲に設けた構成において、前記中心軸周り
に巻回した閉回路をなす遮蔽コイルを前記検出コイル及
び前記励磁コイルの周囲に設けたことにある。同構成に
よれば、遮蔽コイルを設けたことにより、励磁コイル及
び検出コイルの周囲に反磁界が発生する。その結果、コ
アの中心軸方向に沿った磁束の拡散を抑制している。In order to achieve the above object, a feature of the sensor head for eddy current detection according to the present invention is that a detection coil and an exciting coil wound around a central axis of a core are provided around the core. In the above configuration, a shield coil wound around the central axis and forming a closed circuit is provided around the detection coil and the excitation coil. According to this configuration, the provision of the shielding coil generates a demagnetizing field around the excitation coil and the detection coil. As a result, the diffusion of the magnetic flux along the center axis direction of the core is suppressed.
【０００６】また、前記遮蔽コイルと前記検出コイル及
び前記励磁コイルとを前記中心軸方向に相対移動させる
ことにより、前記遮蔽コイルと前記検出コイル及び前記
励磁コイルとの重なり量を調節することの可能な重なり
調整機構を設けてもよい。さらに、前記遮蔽コイルが両
端の中間にタップを有しており、このタップを選択的に
利用して前記遮蔽コイルの閉回路長を変更可能な切り替
えスイッチを設けてもよい。これら遮蔽コイルの重なり
量や遮蔽コイルの閉回路長を調整することで、反磁界の
発生量を調整し、センサヘッドの検出精度を最適化する
ことが可能となる。Further, by moving the shield coil, the detection coil, and the excitation coil relatively in the direction of the central axis, the amount of overlap between the shield coil, the detection coil, and the excitation coil can be adjusted. An overlap adjustment mechanism may be provided. Further, the shield coil may have a tap in the middle of both ends, and a changeover switch capable of changing the closed circuit length of the shield coil by selectively using the tap may be provided. By adjusting the amount of overlap of the shielding coils and the closed circuit length of the shielding coils, it is possible to adjust the amount of generation of the demagnetizing field and optimize the detection accuracy of the sensor head.
【０００７】[0007]
【発明の実施の形態】次に、図面を参照しながら、本発
明の実施形態について説明する。図１に示すように、本
発明に係るパルス渦流探傷用センサヘッド１は、コア２
の周りにこのコア２の中心線Ｌを中心に検出コイル３、
励磁コイル４及び遮蔽コイル５を順次巻回してなる。各
コイル３，４，５の中心線Ｌ方向の長さは、検出コイル
３よりも励磁コイル４が長く、さらに励磁コイル４より
も遮蔽コイル５が長い。励磁コイル４は、入力端子に加
えられる図２のＩＮに示す波形により被検体に渦電流を
発生させる。そして、この渦電流に起因する磁束が傷に
より変化する状況を検出コイル３により捉える。特に、
遮蔽コイル５による反磁界の発生で励磁コイル４から発
生する磁束を被検体に集中させるべく、励磁コイル４
は、中心線Ｌに直交する側面視で遮蔽コイル５に隠れる
ように配置することが望ましい。Next, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a sensor head 1 for pulse eddy current testing according to the present invention includes a core 2
Around the center line L of the core 2 around the detection coil 3,
The exciting coil 4 and the shielding coil 5 are sequentially wound. The length of each of the coils 3, 4, 5 in the direction of the center line L is longer in the excitation coil 4 than in the detection coil 3, and further, longer in the shielding coil 5 than in the excitation coil 4. The exciting coil 4 generates an eddy current in the subject according to the waveform indicated by IN in FIG. 2 applied to the input terminal. Then, a situation in which the magnetic flux caused by the eddy current changes due to a flaw is detected by the detection coil 3. In particular,
In order to concentrate the magnetic flux generated from the exciting coil 4 by the generation of the demagnetizing field by the shielding coil 5 on the subject, the exciting coil 4
Is desirably arranged so as to be hidden by the shielding coil 5 in a side view orthogonal to the center line L.
【０００８】検出コイル３により検出される波形は、図
２のＯＵＴの如き波形となる。ＯＵＴ波形のうち下側に
突出する符号Ｋの部分を検波により反転させて表示した
のが図３に示すグラフである。同図では、健全部信号ｆ
（ｔ）と欠陥部信号ｇ（ｔ）とを表示する。また、同図
の横軸原点は、ＩＮパルスの終了時刻であり、横軸をな
すｔをパルス終了後時間と称する。[0008] The waveform detected by the detection coil 3 becomes a waveform like OUT in FIG. FIG. 3 is a graph in which the portion of the OUT waveform, which protrudes downward, is indicated by the symbol K, which is inverted by detection and displayed. In the figure, the sound part signal f
(T) and the defective portion signal g (t) are displayed. The origin of the horizontal axis in the figure is the end time of the IN pulse, and t forming the horizontal axis is referred to as the time after the end of the pulse.
【０００９】健全部信号ｆ（ｔ）は基準信号であり、欠
陥部信号ｇ（ｔ）はある部位における測定信号である。
あるパルス終了後時刻ｔnにおける健全部信号ｆ（ｔ）
の二次パルス電圧に同じ値となる欠陥部信号ｇ（ｔ）の
時刻と先の時刻ｔnとの差を基準信号時間差Δｔnと称す
る。本発明では、この基準信号時間差Δｔnを電圧信号
に変換して直接的に評価の対象とする。The healthy part signal f (t) is a reference signal, and the defective part signal g (t) is a measurement signal at a certain part.
Sound part signal f (t) at time tn after the end of a certain pulse
The difference between the time of the defect signal g (t) having the same value as the secondary pulse voltage and the previous time tn is referred to as a reference signal time difference Δtn. In the present invention, this reference signal time difference Δtn is converted into a voltage signal and directly subjected to evaluation.
【００１０】図４に示すように、本発明に係るパルス渦
流探傷器１０は、センサユニット２０、中継ユニット３
０及びパーソナルコンピュータ４０とＣＲＴモニタ５１
及びプリンター５２とよりなる。Ｙ軸エンコーダ２２
は、先のパルス渦流探傷用センサヘッド１の他に、パル
ス渦流探傷用センサヘッド１をＸＹ軸方向に沿ってそれ
ぞれ移動させるための図示しない２軸テーブル機構を有
する。また、このテーブル機構によるパルス渦流探傷用
センサヘッド１の移動座標は、Ｘ軸エンコーダ２１及び
Ｙ軸エンコーダ２２によって検出される。As shown in FIG. 4, a pulse eddy current flaw detector 10 according to the present invention comprises a sensor unit 20 and a relay unit 3.
0 and personal computer 40 and CRT monitor 51
And a printer 52. Y-axis encoder 22
Has a two-axis table mechanism (not shown) for moving the sensor head 1 for pulse eddy current detection along the X and Y axes in addition to the sensor head 1 for pulse eddy current detection described above. The moving coordinates of the pulse eddy current flaw detection sensor head 1 by the table mechanism are detected by the X-axis encoder 21 and the Y-axis encoder 22.
【００１１】パーソナルコンピュータ４０は、Ａ／Ｄコ
ンバーター３６を介して各種機器を制御し、Ａ／Ｄコン
バーター３６及びＩ／Ｏ変換器３８を通してデータを取
り込んで処理する。このパーソナルコンピュータ４０
は、中央演算装置４１と、入力制御用Ｉ／Ｏコントロー
ラー４２と、データを一時記憶するメモリ４４と、デー
タ及びプログラムを常時記憶するハードディスク４５と
を備えている。また、データバス、アドレスバスよりな
る各種バス４３により、これら各部材が接続されてい
る。そして、これら各部材は、各種機器の制御及びデー
タ処理のためのキーボード４６及びマウス４７により操
作され、その処理結果は、ビデオアクセラレーター４８
を介してＣＲＴモニタ５１に表示されると共に、プリン
ター５２にプリントアウトされる。The personal computer 40 controls various devices via the A / D converter 36, and takes in data through the A / D converter 36 and the I / O converter 38 for processing. This personal computer 40
Has a central processing unit 41, an input control I / O controller 42, a memory 44 for temporarily storing data, and a hard disk 45 for constantly storing data and programs. These members are connected by various buses 43 including a data bus and an address bus. These components are operated by a keyboard 46 and a mouse 47 for controlling various devices and processing data, and the processing results are output to a video accelerator 48.
Are displayed on the CRT monitor 51 via the printer and printed out on the printer 52.
【００１２】中継ユニット３０におけるパルス発生器３
１は、パーソナルコンピュータ４０の操作により先のＩ
Ｎパルスを発生し、パルス渦流探傷用センサヘッド１の
励磁コイル４に加える。また、検出コイル３により検出
されたＯＵＴ信号は、増幅器３２により増幅された後、
ｔ／Ｖ中継器３４においてパーソナルコンピュータ４０
から中継ユニット３０を介して入力された先の健全部信
号ｆ（ｔ）との比較がなされて、先の基準信号時間差Δ
ｔが求められる。波形処置部３５は、ｔ／Ｖ中継器３４
に求められた基準信号時間差をΔｔを電圧信号に変換
し、Ａ／Ｄコンバーター３６を介してパーソナルコンピ
ュータ４０に入力すると共にこれを表示する。パルス渦
流探傷用センサヘッド１のＸＹ座標は、Ｘ軸エンコーダ
２１及びＹ軸エンコーダ２２から発生するパルスをカウ
ンター３７によりカウントすることで、Ｉ／Ｏ変換器３
８を介してパーソナルコンピュータ４０に入力される。
そして、先の基準信号時間差Δｔは各座標毎にパーソナ
ルコンピュータ４０により表示される。The pulse generator 3 in the relay unit 30
1 is an operation of the personal computer 40.
An N pulse is generated and applied to the exciting coil 4 of the pulse eddy current flaw detection sensor head 1. The OUT signal detected by the detection coil 3 is amplified by the amplifier 32,
The personal computer 40 in the t / V repeater 34
Is compared with the previous sound part signal f (t) input from the relay unit 30 via the relay unit 30, and the previous reference signal time difference Δ
t is determined. The waveform treatment unit 35 includes a t / V repeater 34
Is converted to a voltage signal, which is input to the personal computer 40 via the A / D converter 36 and displayed. The XY coordinates of the sensor head 1 for pulse eddy current flaw detection are obtained by counting the pulses generated from the X-axis encoder 21 and the Y-axis encoder 22 by the counter 37, and the I / O converter 3
8 to the personal computer 40.
The reference signal time difference Δt is displayed by the personal computer 40 for each coordinate.
【００１３】図５に従来型のセンサヘッドと本発明に係
る遮蔽コイル５を含むセンサヘッドとの効果の差異を表
すデータを示す。各グラフは、図３のグラフのピークを
過ぎた後半部に相当する。図５（ａ）は従来型のセンサ
ヘッドであり、信号値は比較的早く零に到達している。
一方、図５（ｂ）では、図１における直径ｄ＝１ｍｍの
銅線を長さｈ＝４２ｍｍだけ巻付けて遮蔽コイル５を作
成してある。また、図５（ｂ）から（ｅ）に至るにした
がって、遮蔽コイル５の巻回数が１層巻、２層巻、３層
巻、４層巻と多くなっているが、同時に二次パルス電流
はより緩やかに減衰するようになっていく。遮蔽コイル
５の巻回数が増えることで遮蔽コイル５による反磁界も
増加し、これに伴って、減衰も緩やかになったものと考
えられる。そして、減衰が緩やかになるにしたがって基
準信号時間差Δｔが増大し、検出精度も向上する。FIG. 5 shows data indicating the difference in effect between the conventional sensor head and the sensor head including the shielding coil 5 according to the present invention. Each graph corresponds to the latter half of the graph of FIG. FIG. 5A shows a conventional sensor head, in which the signal value reaches zero relatively quickly.
On the other hand, in FIG. 5B, the shielding coil 5 is formed by winding a copper wire having a diameter d = 1 mm in FIG. 1 by a length h = 42 mm. 5 (b) to 5 (e), the number of turns of the shielding coil 5 is increased to one-layer winding, two-layer winding, three-layer winding, and four-layer winding. Decay more slowly. It is considered that the demagnetizing field caused by the shielding coil 5 also increased due to the increase in the number of turns of the shielding coil 5, and the attenuation was moderated accordingly. Then, as the attenuation becomes gentle, the reference signal time difference Δt increases, and the detection accuracy also improves.
【００１４】[0014]
【実施例】次に、図６〜図８を参照しながら本発明の第
一実施例について説明する。図６は、検査対象として断
熱配管１００を用いた場合の横断面図を示している。こ
の断熱配管１００は、被検査体たる管１０１の周囲に保
温用の断熱材１０２及び外装材１０３を順次設けてな
る。管１０１には、直径ｄの疑似欠陥たる人工凹部１０
１ａを形成してあり、パルス渦流探傷用センサヘッド１
は距離Ｍのリフトオフをもって管１０１表面と隔てられ
ている。このパルス渦流探傷用センサヘッド１は、断熱
配管１００の軸方向に往復運動すると共に断熱配管１０
０の円周方向に順次回転運動を行い、断熱配管１００の
表面をくまなく走査することとなる。Next, a first embodiment of the present invention will be described with reference to FIGS. FIG. 6 shows a cross-sectional view when the heat insulating pipe 100 is used as an inspection target. The heat-insulating pipe 100 includes a heat-insulating material 102 and a packaging material 103 sequentially provided around a tube 101 as an object to be inspected. The tube 101 has an artificial recess 10 serving as a pseudo defect having a diameter d.
1a, and a sensor head 1 for pulse eddy current flaw detection
Is separated from the surface of the tube 101 by a lift-off of a distance M. The pulse eddy current flaw detection sensor head 1 reciprocates in the axial direction of the heat insulating pipe 100 and the heat insulating pipe 10.
Rotational motion is sequentially performed in the circumferential direction of 0, and the entire surface of the heat insulating pipe 100 is scanned.
【００１５】図７（ａ）は、基準信号時間差Δｔを電圧
信号に修正した時間差電圧Δｔ・Ｖとパルス終了時間ｔ
の関係を示す。直径ｄ＝５０ｍｍ深さ３ｍｍの人工凹部
１０１ａを形成した１８インチ管１０１を被検体とし、
リフトオフ量Ｍ＝４０ｍｍとして、従来型のセンサヘッ
ドと本願発明に係るセンサヘッドとの比較を行った。正
方形で示す本願センサヘッドを用いた場合は、丸印で示
す従来型センサヘッドを用いた場合に比較して縦軸の時
間差電圧Δｔ・Ｖは必ず大であることが明らかとなっ
た。一方、図７では、パルス終了後時間と時間差電圧の
Ｓ／Ｎ比との関係を示すグラフである。人工凹部１０１
ａ及び管１０１は先の図７（ａ）に示す場合と同様であ
る。Ｓ／Ｎ比についても正方形に示す本願発明に係るセ
ンサヘッドを用いた場合には、丸印に示す従来型センサ
ヘッドを用いた場合よりも必ず大となっている。FIG. 7A shows a time difference voltage Δt · V obtained by correcting the reference signal time difference Δt into a voltage signal and a pulse end time t.
Shows the relationship. An 18-inch tube 101 having an artificial concave portion 101a having a diameter d = 50 mm and a depth of 3 mm was used as a subject,
With the lift-off amount M = 40 mm, a comparison was made between the conventional sensor head and the sensor head according to the present invention. When the present sensor head indicated by a square is used, it is clear that the time difference voltage Δt · V on the vertical axis is always larger than when the conventional sensor head indicated by a circle is used. On the other hand, FIG. 7 is a graph showing the relationship between the time after the end of the pulse and the S / N ratio of the time difference voltage. Artificial recess 101
a and the pipe 101 are the same as those shown in FIG. The S / N ratio is always larger when the sensor head according to the present invention shown in a square is used than when the conventional sensor head shown by a circle is used.
【００１６】一方、図８に示すように、黒丸及び黒四角
で表示した本願発明に係るセンサヘッドによる時間差電
圧Δｔ・Ｖは、白丸及び白四角で表示した従来型センサ
を用いた場合に比較して常に大となっている。これら図
７及び図８に係る実験結果より、本願発明に係るセンサ
ヘッドの優位性が証明された。また、これらの実験結果
より、通常の交流を用いた渦流探傷でも磁束の拡散を抑
制して検出精度を向上させ得ることが当然類推される。On the other hand, as shown in FIG. 8, the time difference voltage Δt · V by the sensor head according to the present invention indicated by black circles and black squares is compared with the case where the conventional sensor indicated by white circles and white squares is used. Is always big. 7 and 8, the superiority of the sensor head according to the present invention was proved. From these experimental results, it can be naturally inferred that even in eddy current flaw detection using ordinary alternating current, the diffusion of magnetic flux can be suppressed and the detection accuracy can be improved.
【００１７】次に、図９〜図１２を参照しながら本発明
の第二実施例について説明する。図９（ａ）に示すよう
に、本実施例では検査対象に厚みＤのコンクリート板１
１１の裏側に試験体たる鉄筋１１２を一定間隔Ｎで複数
本並べている。そして、パルス渦流探傷用センサヘッド
１の中心線Ｌを直交させる姿勢でコンクリート板１１１
の表面に沿ってパルス渦流探傷用センサヘッド１を走査
させている。なお、図１２の如く鉄筋経を変化させる場
合には、図９（ｂ）の如く、各部位に鉄筋を複数本密着
させて設けている。Next, a second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 9A, in this embodiment, a concrete plate 1 having a thickness D
A plurality of rebars 112 as test specimens are arranged at a constant interval N on the back side of 11. Then, the concrete plate 111 is positioned in such a manner that the center line L of the pulse eddy current flaw detection sensor head 1 is orthogonal.
The pulse eddy current flaw detection sensor head 1 is caused to scan along the surface of the sensor. In the case where the reinforcing bar diameter is changed as shown in FIG. 12, a plurality of reinforcing bars are provided in close contact with each part as shown in FIG. 9B.
【００１８】図１０は、センサヘッド１と基準信号時間
差Δｔとの関係を示すグラフである。同グラフに示す基
準値Ｃは、鉄筋１１２を設けないコンクリート板１１１
のみの値であり図３における関数ｆ（ｔ）の場合に相当
する。一方、三つのピークに相当する部分は、鉄筋１１
２の真上にパルス渦流探傷用センサヘッド１が位置する
場合であって、図３における関数ｇ（ｔ）の場合に相当
する。二つの谷の部分は、各鉄筋１１２の間を意味す
る。ピークと基準値Ｃとの差をＡ、谷と基準値Ｃとの差
をＢとすれば、鉄筋検出の分解能は２０ｌｏｇ（Ａ／
Ｂ）で定義される。FIG. 10 is a graph showing the relationship between the sensor head 1 and the reference signal time difference Δt. The reference value C shown in the graph is a concrete plate 111 without the reinforcing bar 112.
And corresponds to the case of the function f (t) in FIG. On the other hand, the portions corresponding to the three peaks
This is a case where the pulse eddy current flaw detection sensor head 1 is located directly above the position 2 and corresponds to the case of the function g (t) in FIG. The two valleys mean between the reinforcing bars 112. Assuming that the difference between the peak and the reference value C is A and the difference between the valley and the reference value C is B, the rebar detection resolution is 20 log (A /
B).
【００１９】図１１は、鉄筋１１２の配筋間隔Ｎと分解
能との関係を示す。丸印は、コンクリート板１１１の被
り厚さＤが８０ｍｍ、正方形印は同被り厚さＤが１００
ｍｍの場合である。また、黒丸及び黒四角は従来型セン
サヘッドを用いた場合を示し、白丸及び白四角は本願発
明に係るセンサヘッドを用いた場合を意味する。同結果
からも、本願発明に係るセンサヘッドの方が分解能が高
いことが確認された。FIG. 11 shows the relationship between the arrangement interval N of the reinforcing bars 112 and the resolution. The circle mark indicates that the covering thickness D of the concrete plate 111 is 80 mm, and the square mark indicates that the covering thickness D is 100 mm.
mm. Further, black circles and black squares indicate the case where the conventional sensor head is used, and white circles and white squares indicate the case where the sensor head according to the present invention is used. These results also confirm that the sensor head according to the present invention has higher resolution.
【００２０】図１２は、鉄筋経を１９ｍｍ、３８ｍｍ及
び５７ｍｍと擬似的に異ならせて被り厚さＤを変化させ
た場合の基準信号時間差Δｔの関係を示す。係数（Δｔ
２−Δｔ１）／（ｔ２−ｔ１）におけるｔ２及びｔ１は
任意の値であり、この係数はΔｔの傾きを示すものであ
る。同試験によれば、この係数を用いることで鉄筋経に
関わらずコンクリートの被り厚さＤを求めることは可能
となることが確認された。FIG. 12 shows the relationship between the reference signal time differences Δt when the covering thickness D is changed by making the reinforcing steel bars pseudo-different to 19 mm, 38 mm and 57 mm. Coefficient (Δt
T2 and t1 in (2-Δt1) / (t2-t1) are arbitrary values, and this coefficient indicates the slope of Δt. According to the same test, it was confirmed that the use of this coefficient makes it possible to determine the covering thickness D of the concrete regardless of the reinforcement.
【００２１】最後に、本発明のさらに別の実施形態につ
いて説明する。なお、上記実施形態と同様の部材には同
様の符号を付してある。Finally, another embodiment of the present invention will be described. The same members as those in the above embodiment are denoted by the same reference numerals.
【００２２】上記第一実施形態では、検出コイル３及び
励磁コイル４と遮蔽コイル５とが側面視で完全に重なる
ようにこれらを配置した。しかし、図１３に示すよう
に、検出コイル３及び励磁コイル４と遮蔽コイル５との
間にこれらの側面視での重なり量Ｗを調節する重なり調
整機構６を設けても良い。この重なり調整機構６は、遮
蔽コイル５を巻き付ける可動調整部材７とコア２に取り
付ける固定調整部材８とよりなる。可動調整部材７の下
部には、遮蔽コイル５を巻き付ける円筒状のスプール７
ａを有し、スプール７ａの両端にはそれぞれフランジ７
ｂ，７ｂを有している。一方、可動調整部材７の上部に
は雌ねじ部７ｃを設けてあり、この雌ねじ部７ｃは、固
定調整部材８の外面に設けた雄ねじ部８ａに螺合して可
動調整部材７と固定調整部材８との相対回転で中心先Ｌ
方向に遮蔽コイル５を移動させる。重なり量Ｗの調節に
より、ΔｔとＳ／Ｎ比とを最良の値とすることが可能と
なる。In the first embodiment, the detection coil 3, the excitation coil 4, and the shielding coil 5 are arranged such that they completely overlap in a side view. However, as shown in FIG. 13, an overlap adjusting mechanism 6 for adjusting the overlap amount W in side view may be provided between the detection coil 3 and the exciting coil 4 and the shielding coil 5. The overlap adjustment mechanism 6 includes a movable adjustment member 7 around which the shielding coil 5 is wound and a fixed adjustment member 8 attached to the core 2. A cylindrical spool 7 around which the shielding coil 5 is wound is provided below the movable adjusting member 7.
a at each end of the spool 7a.
b, 7b. On the other hand, a female screw portion 7c is provided on the upper portion of the movable adjustment member 7, and the female screw portion 7c is screwed into a male screw portion 8a provided on the outer surface of the fixed adjustment member 8, and is connected to the movable adjustment member 7 and the fixed adjustment member 8. Center point L by relative rotation with
The shielding coil 5 is moved in the direction. By adjusting the overlap amount W, it is possible to make Δt and the S / N ratio the best values.
【００２３】一方、図１４に示す実施形態では遮蔽コイ
ル５が端部５ａ，５ａの中間に複数のタップ５ｂ，５ｃ
を有している。また、一方の端部５ａと他方の端部５ａ
及びタップ５ｂ，５ｃとの間に切り替えスイッチ５ｄを
設けてある。そして、切り替えスイッチ５ｄの切り替え
により、第一タップ５ｂ及び第二タップ５ｃを選択的に
利用して巻回数を変更させ、第二実施形態同様、Δｔと
Ｓ／Ｎ比を最適な値に調節可能である。On the other hand, in the embodiment shown in FIG. 14, the shielding coil 5 has a plurality of taps 5b, 5c in the middle of the ends 5a, 5a.
have. Also, one end 5a and the other end 5a
A changeover switch 5d is provided between the switch 5 and the taps 5b and 5c. Then, by switching the changeover switch 5d, the first tap 5b and the second tap 5c are selectively used to change the number of windings, and the Δt and the S / N ratio can be adjusted to optimal values as in the second embodiment. It is.
【００２４】上記第一実施形態では、長尺の管１０１及
び鉄筋１１２などを被験体とした。しかし、被検体に
は、塊状や板状の鉄、銅、アルミニウム等の導電体を用
いても構わない。In the first embodiment, the long tube 101, the reinforcing bar 112, and the like were used as the test subjects. However, a lump-shaped or plate-shaped conductor such as iron, copper, or aluminum may be used for the subject.
【００２５】[0025]
【発明の効果】このように、上記本発明に係る渦流探傷
用センサヘッドの特徴によれば、遮蔽コイルによる反磁
界の発生でコア中心軸方向に沿う磁束の拡散を抑制し、
被検体とセンサヘッドとの間にリフトオフがあっても従
来より高精度で且つ分解能の高いパルス渦流探傷検査を
行うことが可能となった。その結果、例えば、断熱配管
や鉄筋コンクリートの鉄筋検出等を従来よりも高精度で
検査することが可能となった。また、本発明の上記特徴
によれば、通常の交流波を用いた渦流探傷用センサヘッ
ドの検出精度をも向上させ得るようになった。As described above, according to the feature of the sensor head for eddy current detection according to the present invention, the generation of a demagnetizing field by the shield coil suppresses the diffusion of the magnetic flux along the core central axis direction.
Even if there is a lift-off between the subject and the sensor head, it is possible to perform pulse eddy current flaw detection inspection with higher precision and higher resolution than before. As a result, for example, it has become possible to inspect, for example, heat insulation pipes and detection of reinforcing bars of reinforced concrete with higher accuracy than before. Further, according to the above feature of the present invention, the detection accuracy of the eddy current flaw detection sensor head using a normal AC wave can be improved.
【００２６】なお、特許請求の範囲の項に記入した符号
は、あくまでも図面との対照を便利にするためのものに
すぎず、該記入により本発明は添付図面の構成に限定さ
れるものではない。It should be noted that reference numerals written in the claims are merely for convenience of comparison with the drawings, and the present invention is not limited to the structure of the attached drawings by the writing. .
【図１】本発明に係るパルス渦流探傷用センサヘッドの
縦断面図である。FIG. 1 is a longitudinal sectional view of a sensor head for pulse eddy current inspection according to the present invention.
【図２】ＩＮは励磁コイルへの入力信号を示し、ＯＵＴ
は検出コイルからの出力信号を示すグラフである。FIG. 2 shows an input signal to an exciting coil, and OUT
Is a graph showing an output signal from the detection coil.
【図３】検出コイルにおける時間と二次パルス電圧との
関係を示すグラフであって、ｆ（ｔ）は健全部の信号、
ｇ（ｔ）は欠陥部の信号をそれぞれ示す関数である。FIG. 3 is a graph showing a relationship between time and a secondary pulse voltage in a detection coil, where f (t) is a signal of a healthy part,
g (t) is a function indicating the signal of the defective portion, respectively.
【図４】本発明に係るパルス渦流探傷器の構成を示すブ
ロック図である。FIG. 4 is a block diagram showing a configuration of a pulse eddy current flaw detector according to the present invention.
【図５】検出コイルに現れる二次パルス電圧の後半部の
時間変化を従来型センサヘッドと図１に係る本発明に係
るセンサヘッドとで比較した例を示し、（ａ）は遮蔽コ
イルを有さない従来型のセンサヘッドを用いた場合、
（ｂ）は直径１ｍｍの導線を互いに密接させて４２回巻
回した場合、（ｃ）は直径１ｍｍの導線を（ｂ）の倍だ
け二層巻きにした場合、（ｄ）は直径１ｍｍの導線を
（ｂ）の３倍だけ３層巻きにした場合、（ｅ）は直径１
ｍｍの導線を（ｂ）の４倍だけ４層巻きにした場合をそ
れぞれ示すデータである。5 shows an example in which the time change of the second half of the secondary pulse voltage appearing in the detection coil is compared between the conventional sensor head and the sensor head according to the present invention shown in FIG. 1, and FIG. If a conventional sensor head is used,
(B) is a case where a wire having a diameter of 1 mm is wound 42 times in close contact with each other, (c) is a case where a wire having a diameter of 1 mm is wound twice as much as (b), and (d) is a wire having a diameter of 1 mm. When three layers are wound by three times as large as (b), (e) has a diameter of 1
This is data showing the case where the conductor wire of mm is wound in four layers by four times the length of (b).
【図６】断熱材で保護された配管を本発明に係るセンサ
ヘッドで検査する状態を説明する管横断面図である。FIG. 6 is a cross-sectional view of the pipe explaining a state where the pipe protected by the heat insulating material is inspected by the sensor head according to the present invention.
【図７】遮蔽コイルを有さない従来型のセンサヘッドと
本発明に係るセンサヘッドとの比較例を示し、（ａ）は
パルス電圧付与終了時からのパルス終了後時間ｔと同時
刻ｔにおける基準信号に対する基準信号時間差Δｔとの
関係を示すグラフであり、（ｂ）は時刻遅れｔとＳ／Ｎ
比との関係を示すグラフである。7A and 7B show a comparative example of a conventional sensor head having no shielding coil and a sensor head according to the present invention, and FIG. 7A shows a comparison between the time t after the end of pulse voltage application and the time t after the end of pulse voltage application. 6 is a graph showing a relationship between a reference signal time difference Δt and a reference signal, and FIG.
It is a graph which shows the relationship with a ratio.
【図８】配管におけるリフトオフ量と基準信号からの時
間遅れ量との関係を遮蔽コイルを有さない従来型センサ
ヘッドと本発明に係る遮蔽センサヘッドとで比較したグ
ラフであって、（ａ）は被検体に直径ｄ＝７５ｍｍ深さ
３ｍｍの人工凹部を形成した直径１８インチの管を用い
た場合、（ｂ）は被検体に直径ｄ＝５０ｍｍ深さ３ｍｍ
の人工凹部を形成した直径１８インチの管を用いた場
合、（ｃ）は被検体に直径ｄ＝２５ｍｍ深さ３ｍｍの人
工凹部を形成した直径１８インチの管を用いた場合をそ
れぞれ示す。FIG. 8 is a graph comparing the relationship between the lift-off amount in a pipe and the amount of time delay from a reference signal between a conventional sensor head having no shielding coil and the shielded sensor head according to the present invention, and (a). Is a case where a 18-inch diameter tube in which an artificial concave part having a diameter d = 75 mm and a depth 3 mm is formed on the subject, (b) shows a case where the subject has a diameter d = 50 mm and a depth 3 mm
(C) shows a case in which an 18-inch diameter tube having an artificial recess having a diameter d = 25 mm and a depth of 3 mm was used as a subject.
【図９】本発明の第二実施例に係る鉄筋コンクリートに
おける背筋間隔を調査するための被検体の横断面図を示
し、（ａ）はコンクリート板の下に一定間隔で一本ずつ
鉄筋を配置した場合、（ｂ）は鉄筋を一カ所に数本ずつ
設けた場合を示す図である。FIG. 9 is a cross-sectional view of a test object for investigating a back-spacing in reinforced concrete according to the second embodiment of the present invention. FIG. 9 (a) shows a case in which reinforcing bars are arranged one by one under a concrete plate at regular intervals. In this case, (b) is a diagram showing a case where several reinforcing bars are provided in one place.
【図１０】センサヘッド位置とΔｔの強度との関係の一
例を示すグラフである。FIG. 10 is a graph showing an example of a relationship between a sensor head position and an intensity of Δt.
【図１１】遮蔽コイルを有さない従来型の遠距離センサ
ヘッドと本発明に係る遮蔽センサヘッドとのそれぞれに
ついてコンクリート板の被り厚さを異ならせ、配筋間隔
Ｎと分解能との関係を求めたグラフである。FIG. 11 shows the relationship between the rebar arrangement interval N and the resolving power of the conventional long-distance sensor head having no shielding coil and the shielding sensor head according to the present invention, each having a different covering thickness of the concrete plate. FIG.
【図１２】鉄筋径を異ならせて求めた被り厚さＤと基準
信号時間差の傾きを示す系数との関係を示すグラフであ
る。FIG. 12 is a graph showing a relationship between a cover thickness D obtained by changing the diameter of a reinforcing bar and a modulus indicating a slope of a reference signal time difference.
【図１３】本発明に係る別の実施形態を示す図１相当図
である。FIG. 13 is a diagram corresponding to FIG. 1, showing another embodiment according to the present invention.
【図１４】本発明に係るセンサヘッドのさらに別の実施
形態を示す回路図である。FIG. 14 is a circuit diagram showing still another embodiment of the sensor head according to the present invention.
１ パルス渦流探傷用センサヘッド ２ コア（フェライトコア） ３ 検出コイル ４ 励磁コイル ５ 遮蔽コイル ５ａ 端部 ５ｂ 第一タップ ５ｃ 第二タップ ５ｄ 切り替えスイッチ ６ 重なり調整機構 ７ 可動調整部材 ７ａ スプール ７ｂ フランジ ７ｃ 雌ねじ部 ８ 固定調整部材 ８ａ 雄ねじ部 １０ パルス渦流探傷器 ２０ センサユニット ２１ Ｘ軸エンコーダ ２２ Ｙ軸エンコーダ ３０ 中継ユニット ３１ パルス発生器 ３２ 増幅器 ３３ ローパスフィルター ３４ ｔ／Ｖ中継器 ３５ 波形処理部 ３６ Ａ／Ｄコンバーター ３７ カウンター ３８ Ｉ／Ｏ変換器 ４０ パーソナルコンピュータ ４１ 中央演算装置 ４２ Ｉ／Ｏコントローラー ４３ バス ４４ メモリ ４５ ハードディスク ４６ キーボード ４７ マウス ４８ ビデオアクセラレーター ５１ ＣＲＴモニタ ５２ プリンター ｆ（ｔ）健全部信号 ｇ（ｔ）欠陥部信号 Ｌ 中心線 ｄ 遮蔽コイル厚 ｈ 遮蔽コイル高 Ｍ リフトオフ量 Ｄ コンクリート厚 Ｎ 鉄筋配置間隔 Ｗ 重なり量 ｔ パルス終了後時間 Δｔ 基準信号時間差 Δｔ・Ｖ時間差電圧 １００ 断熱配管 １０１ 管 １０１ａ人工凹部 １０２ 断熱材 １０３ 外装材 １１０ 疑似鉄筋構造物 １１１ コンクリート板 １１２ 鉄筋 DESCRIPTION OF SYMBOLS 1 Sensor head for pulse eddy current inspection 2 Core (ferrite core) 3 Detection coil 4 Exciting coil 5 Shielding coil 5a End 5b First tap 5c Second tap 5d Changeover switch 6 Overlap adjustment mechanism 7 Movable adjustment member 7a Spool 7b Flange 7c Female screw Part 8 Fixed adjusting member 8a Male screw part 10 Pulse eddy current flaw detector 20 Sensor unit 21 X-axis encoder 22 Y-axis encoder 30 Relay unit 31 Pulse generator 32 Amplifier 33 Low-pass filter 34 t / V relay 35 Waveform processing unit 36 A / D Converter 37 Counter 38 I / O converter 40 Personal computer 41 Central processing unit 42 I / O controller 43 Bus 44 Memory 45 Hard disk 46 Keyboard 47 Mouse 48 Video accelerator 51 RT monitor 52 Printer f (t) sound part signal g (t) defective part signal L Center line d Shield coil thickness h Shield coil height M Lift-off amount D Concrete thickness N Rebar arrangement interval W Overlap amount t Time after pulse Δt Reference signal Time difference Δt · V Time difference voltage 100 Insulated pipe 101 Pipe 101a Artificial recess 102 Insulation material 103 Exterior material 110 Pseudo-reinforcement structure 111 Concrete plate 112 Reinforcing bar
───────────────────────────────────────────────────── フロントページの続き (72)発明者 吉荒 俊克 大阪市西区北堀江１丁目18番14号 非破壊 検査株式会社内 (72)発明者 今中 拓一 大阪市西区北堀江１丁目18番14号 非破壊 検査株式会社内 Ｆターム(参考） 2G053 AA11 AB21 BA12 BA13 BA21 BA26 BC05 BC14 CA03 CB10 DA01 DB04 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshikatsu Yoshiara 1-1-18-14 Kitahorie, Nishi-ku, Osaka City Inside Nondestructive Inspection Co., Ltd. (72) Inventor Takuichi Imanaka 1-1-18-14 Kitahorie, Nishi-ku, Osaka City No. Non-Destructive Inspection Co., Ltd. F-term (reference) 2G053 AA11 AB21 BA12 BA13 BA21 BA26 BC05 BC14 CA03 CB10 DA01 DB04
Claims (3)
た検出コイル（３）及び励磁コイル（４）を前記コア
（２）の周囲に設けたパルス渦流探傷用センサヘッドで
あって、前記中心軸（Ｌ）周りに巻回した閉回路をなす
遮蔽コイル（５）を前記検出コイル（３）及び前記励磁
コイル（４）の周囲に設けた渦流探傷用センサヘッド。A pulse eddy current flaw detection sensor head comprising a detection coil (3) and an excitation coil (4) wound around a central axis (L) of a core (2) provided around the core (2). A sensor coil for eddy current detection, wherein a shielding coil (5) forming a closed circuit wound around the central axis (L) is provided around the detection coil (3) and the excitation coil (4).
（３）及び前記励磁コイル（４）とを前記中心軸（Ｌ）
方向に相対移動させることにより前記遮蔽コイル（５）
と前記検出コイル（３）及び前記励磁コイル（４）との
重なり量（Ｗ）を調節することの可能な重なり調整機構
（６）を設けてある請求項１に記載の渦流探傷用センサ
ヘッド。2. The shield coil (5), the detection coil (3) and the excitation coil (4) are connected to the central axis (L).
The shielding coil (5)
The sensor head for eddy current detection according to claim 1, further comprising an overlap adjusting mechanism (6) capable of adjusting an overlap amount (W) of the detection coil (3) and the exciting coil (4).
ａ）の中間にタップ（５ｂ，５ｂ）を有しており、この
タップ（５ｂ，５ｂ）を選択的に利用して前記遮蔽コイ
ル（５）の閉回路長を変更可能な切り替えスイッチ（５
ｄ）を設けてある請求項１又は２のいずれかに記載の渦
流探傷用センサヘッド。3. The shield coil (5) has both ends (5a, 5a).
A tap (5b, 5b) is provided in the middle of (a), and the tap (5b, 5b) is selectively used to change the closed circuit length of the shielding coil (5).
3. The sensor head for eddy current testing according to claim 1, wherein d) is provided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10210858A JP2000046802A (en) | 1998-07-27 | 1998-07-27 | Sensor head for eddy current flaw detection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10210858A JP2000046802A (en) | 1998-07-27 | 1998-07-27 | Sensor head for eddy current flaw detection |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2000046802A true JP2000046802A (en) | 2000-02-18 |
Family
ID=16596274
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10210858A Pending JP2000046802A (en) | 1998-07-27 | 1998-07-27 | Sensor head for eddy current flaw detection |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2000046802A (en) |
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| WO2002061412A2 (en) * | 2001-01-29 | 2002-08-08 | Pure Technologies Ltd. | Electromagnetic analysis of concrete tensioning strands |
| KR100592635B1 (en) * | 2002-10-31 | 2006-06-23 | 세안기술 주식회사 | Eddy Current Testing Apparatus |
| CN100392391C (en) * | 2005-01-17 | 2008-06-04 | 林俊明 | Inside-through type low frequency electromagnetic detection sensor |
| JP2009002945A (en) * | 2007-06-12 | 2009-01-08 | Ge Inspection Technologies Ltd | Automatic lift-off compensation for pulsed eddy current inspection |
| JP2010085298A (en) * | 2008-10-01 | 2010-04-15 | Hitachi Ltd | Pulse excitation type eddy current flaw detection method and device |
| JP4766472B1 (en) * | 2010-10-22 | 2011-09-07 | 国立大学法人 岡山大学 | Nondestructive inspection apparatus and nondestructive inspection method |
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| CN109975399A (en) * | 2019-04-25 | 2019-07-05 | 中铁第四勘察设计院集团有限公司 | A kind of rail eddy detection system and method |
| CN110715891A (en) * | 2019-11-20 | 2020-01-21 | 中铁六局集团有限公司 | Concrete gap measuring device and using method thereof |
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- 1998-07-27 JP JP10210858A patent/JP2000046802A/en active Pending
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|---|---|---|---|---|
| EP2458376A3 (en) * | 2001-01-29 | 2012-10-03 | Pure Technologies Ltd | Electromagnetic analysis of concrete tensioning wires |
| WO2002061412A3 (en) * | 2001-01-29 | 2004-07-08 | Pure Technologies Ltd | Electromagnetic analysis of concrete tensioning strands |
| US6781369B2 (en) | 2001-01-29 | 2004-08-24 | Pure Technologies Ltd. | Electromagnetic analysis of concrete tensioning wires |
| US6791318B2 (en) | 2001-01-29 | 2004-09-14 | Pure Technologies Ltd. | Electromagnetic analysis of concrete tensioning wires |
| WO2002061412A2 (en) * | 2001-01-29 | 2002-08-08 | Pure Technologies Ltd. | Electromagnetic analysis of concrete tensioning strands |
| KR100592635B1 (en) * | 2002-10-31 | 2006-06-23 | 세안기술 주식회사 | Eddy Current Testing Apparatus |
| CN100392391C (en) * | 2005-01-17 | 2008-06-04 | 林俊明 | Inside-through type low frequency electromagnetic detection sensor |
| JP2009002945A (en) * | 2007-06-12 | 2009-01-08 | Ge Inspection Technologies Ltd | Automatic lift-off compensation for pulsed eddy current inspection |
| JP2010085298A (en) * | 2008-10-01 | 2010-04-15 | Hitachi Ltd | Pulse excitation type eddy current flaw detection method and device |
| JP4766472B1 (en) * | 2010-10-22 | 2011-09-07 | 国立大学法人 岡山大学 | Nondestructive inspection apparatus and nondestructive inspection method |
| JP2011191326A (en) * | 2011-07-08 | 2011-09-29 | Jfe Steel Corp | Method for detecting surface defect on plate using vortex sensor |
| CN104266665A (en) * | 2014-09-17 | 2015-01-07 | 上海兰宝传感科技股份有限公司 | Method for shielding inductive sensor |
| CN109975399A (en) * | 2019-04-25 | 2019-07-05 | 中铁第四勘察设计院集团有限公司 | A kind of rail eddy detection system and method |
| CN110715891A (en) * | 2019-11-20 | 2020-01-21 | 中铁六局集团有限公司 | Concrete gap measuring device and using method thereof |
| CN111879851A (en) * | 2020-07-23 | 2020-11-03 | 南昌航空大学 | Grating disc pressure equalizing hole crack in-situ eddy current nondestructive testing probe |
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