JP2004138392A

JP2004138392A - Ultrasonic flaw detection apparatus and ultrasonic flaw detection method

Info

Publication number: JP2004138392A
Application number: JP2002300638A
Authority: JP
Inventors: Kenichiro Tsuchiya; 土屋　憲一郎
Original assignee: JFE Koken Co Ltd
Current assignee: JFE Koken Co Ltd
Priority date: 2002-10-15
Filing date: 2002-10-15
Publication date: 2004-05-13
Anticipated expiration: 2022-10-15
Also published as: JP3754669B2

Abstract

<P>PROBLEM TO BE SOLVED: To extremely easily detect inherent defects without damaging an inspection target having a complex shape by an ultrasonic flaw detection apparatus. <P>SOLUTION: Ultrasonic waves are entered into an inspection site to be inspected at a specific angle to a surface to be inspected and at a transmission angle α with a given spread angle from an incident probe 1. A reception probe 10 that receives only ultrasonic waves within a range of a smaller angle than an angle formed by the ultrasonic waves that the incident probe 1 applied and the surface to be inspected, and within a range of a receivable angle β that is smaller than the transmission angle α receives ultrasonic waves that are applied from the incident probe 1 and are transmitted through the inspection target. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、入射探触子で検査対象に超音波を入射し、検査対象を伝達した超音波を受信探触子で受信する超音波探傷装置及び超音波探傷方法に関する。
【０００２】
【従来の技術】
従来から、検査対象を破壊することなく、検査対象に内在する欠陥を検査する超音波探傷として、ＴＯＦＤ（Ｔｉｍｅ　Ｏｆ　Ｆｌｉｇｈｔ　Ｄｉｆｆｒａｃｔｉｏｎ）法が知られている。このＴＯＦＤ法は、図９に示すように、超音波を検査対象に入射させる入射探触子１１０と、超音波を受信する受信探触子１１１とを対向させて検査対象１１２の表面に接触させ、入射探触子１１０から縦波超音波を検査対象１１２に入射させて、内在する欠陥１１３の上端１１４および下端１１５で発生した回析波を受信探触子１１１で受信することで欠陥１１３を探傷する方法である。かかるＴＯＦＤ法では、検査対象１１２の表面に沿って伝播するラテラル波、欠陥１１３の上端１１４及び下端１１５で発生する回析波１２１，１２２、並びに検査対象１１２の底面で反射するエコー波１２３の、入射探触子１１０から受信探触子１１１へ伝播する時間差と音速との関係により欠陥の位置と大きさを正確に検査することができる。
【０００３】
具体的には、図６に示すようにオシロスコープ等の波形を映し出すことができるモニタ装置に、ラテラル波１２０、欠陥の上端で発生する回析波１２１、欠陥の下端で発生する回析波１２２、並びにエコー波１２３を映し出す。そして、各波形の伝播時間を分析することで欠陥の位置と欠陥の大きさを特定している。
【０００４】
このようなＴＯＦＤ法による非破壊検査方法は既に複数の先行技術が開示されている（例えば、特許文献１参照）。
【０００５】
【特許文献１】
特開２００２−１３９４７９号公報　（段落番号００１２〜００１３、図１、段落番号０００３、図６）
【０００６】
【発明が解決しようとする課題】
しかしながら、このＴＯＦＤ法は、検査対象が平面状に形成され、入射探触子と受信探触子とがともに同一平面上に配置されている必要がある。このため、橋桁などの複雑な形状を有する構造物に対しては、ＴＯＦＤ法によって内部欠陥を探傷することが不可能である。近年、橋桁等の複雑な形状を有する構造物について、検査対象を破壊することなく検査できる新たな非破壊検査方法が社会的に望まれている。
【０００７】
本発明は、かかる要請に応えるためになされたものであり、複雑な形状を有する検査対象を破壊することなく、内在する欠陥をきわめて容易に探傷することができる超音波探傷装置及び超音波探傷方法を提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明では、上記課題を解決するために、検査対象の表面と所定の傾斜角をなして、前記検査対象の検査部位側に発信面が向けられた、超音波を発信する発信素子を内蔵し、この発信素子から所定の広がり角度の発信角で検査対象に前記超音波を入射する入射探触子と、前記検査対象の表面と所定の傾斜角をなして、前記検査部位側に受信面が向けられた、前記入射探触子から入射されて前記検査対象を伝達した超音波を受信する受信素子を内蔵し、所定の広がり角度である受信可能角内の超音波のみを受信する受信探触子とを備え、前記受信面と前記検査対象の表面とのなす傾斜角が、前記発信面と前記検査対象の表面とのなす傾斜角より大きく形成されて、前記受信面が前記発信面より相対的に前記検査部位側に大きく傾けられていると共に、前記受信可能角が、前記発信角より小さく形成されている超音波探傷装置を採用した。
【０００９】
また、入射探触子から検査対象の表面に対して所定の角度で、かつ、所定の広がり角の発信角で超音波を前記検査対象の検査部位に向けて入射させ、前記入射探触子が入射した超音波と前記検査対象の表面とがなす角度より小さな角度の範囲内で、かつ、前記発信角より小さな受信可能角の範囲内の超音波のみを受信する受信探触子で、前記入射探触子から入射され、前記検査対象を伝達した超音波を受信することを特徴とする超音波探傷方法により検査対象を探傷する。
【００１０】
本発明によれば、入射探触子から検査対象へ相対的に広い範囲に超音波が入射され、探傷しようとする部位に漏れなく超音波が到達される。その一方で、受信探触子は、接触させた検査対象の表面に相対的に近い方向で、かつ、より小さな角度の範囲内の超音波のみを受信する。これにより、平坦に形成された検査対象だけでなく複雑な形状を有する検査対象に関しても、入射探触子から入射され、検査対象を伝達した超音波を受信探触子が確実に受信する。しかも、受信探触子が、探傷しようとする、限られた範囲から伝達された超音波のみを受信するため、余分なエコー波や回析波を受信せず、高い信頼性を実現する。
【００１１】
また、少なくとも前記傾斜角又は前記発信角のいずれ一方が互いに異なるように形成された複数の入射探触子の中から、前記検査対象に適応した入射探触子を選択し、この入射探触子からこの検査対象の表面とのなす角又は前記発信角のいずれか一方又は双方を変化させて超音波を入射すると共に、少なくとも前記傾斜角又は前記受信可能角のいずれか一方が互いに異なるように形成された複数の受信探触子の中から、前記検査対象に適応した受信探触子を選択し、この受信探触子でこの検査対象の表面とのなす角又は前記受信可能角のいずれか一方又は双方を変化させて、前記入射探触子から入射され、前記検査対象を伝達した超音波を受信する。
【００１２】
さらに、部材同士を所定の角度で交差させて溶接した溶接部が前記検査対象である場合に、前記入射探触子を前記溶接部の溶接ビードの表面に接触せしめて前記超音波を入射させる。上述の発明で不感帯が形成されることを防止することに加え、ビード表面から超音波を入射することで、より効率的に探傷を行うことができる。すなわち、溶接部に内在する欠陥部からの回析波は、部材の裏面から反射するエコー波より確実に先に受信探触子により受信される。このため、片側からの測定で欠陥の有無を判断することができる。
【００１３】
このようして超音波探傷を行うことで、検査対象の形状や探傷しようとする範囲の広さに適応した入射探触子及び受信探触子を適宜選択し、信頼性の高い超音波探傷を行うことができる。
【００１４】
【発明の実施の形態】
以下、本発明の実施の形態について図面を参照しながら説明する。
【００１５】
図１は、本発明の一実施形態にかかる超音波探傷装置を使用して、構造物を構成する２つの部材Ａ，Ｂの溶接部３０を探傷している様子を示している。この図１に示すように、溶接されている一方の部材は水平に延びる梁材Ａであり、他方の部材は、一端から他端に向けて末広がりに形成された斜面を有する台形状部材Ｂである。この実施形態では、超音波探傷装置を使用して、梁材Ａの軸方向の端面と台形状部材Ｂの上底面とが突き合わせ溶接されている溶接部３０の溶け込み不良を探傷している。
【００１６】
この超音波探傷装置は、検査対象である構造物に超音波を入射する入射探触子１と、この入射探触子１から入射され、構造物を伝達してきた超音波を受信する受信探触子１０とを備えている。入射探触子１は梁材Ａの上面に接触されている一方、受信探触子１０は、溶接部３０を入射探触子１と受信探触子１０との間に位置させて、台形状部材Ｂの傾斜面に接触されている。入射探触子１には、この入射探触子１に所定の電圧を印加して入射探触子１から超音波を発信させる発信機２０がケーブルを介して接続されている。一方、受信探触子１０には、この受信探触子１０が発信する、受信した超音波に対応した電気信号を受信する受信機２１がケーブルを介して接続されている。さらに、受信機２１には、受信機２１が受信した電気信号に対応する波形を映し出すモニタ装置２２が接続されている。
【００１７】
この超音波探傷装置では、入射探触子１から縦波の超音波を梁材Ａに入射させ、構造物の表面Ｃに沿って伝達するラテラル波、溶け込み不良３１の上端３２及び下端３３で発生する回析波、並びに梁材Ａの下面Ｄで反射するエコー波を、台形状部材Ｂに接触させている受信探触子１０で受信して、溶け込み不良３１の有無、位置、大きさを検査している。この超音波探傷装置では、入射探触子１が、内蔵された発信素子から所定の広がり角度の発信角αで超音波を梁材Ａに入射すると共に、受信探触子１０が、所定の広がり角を有する受信可能角βの範囲内に伝達されてきた超音波のみを受信するように構成されている。
【００１８】
入射探触子１は梁材Ａの上面に配置されるため、溶接部３０の全域に超音波を伝達させるには、入射探触子１から広い角度で超音波を発信させる必要がある。このため、この入射探触子１では、発信素子が超音波を比較的大きな発信角αで発信しており、溶接部３０の全範囲に漏れなく超音波を到達させている。これに対し、受信探触子１０は、溶接部３０に内在する欠陥のみを検査する必要がある。このため、受信探触子１０は、超音波を受信する範囲を溶接部３０の範囲のみに限定するように、受信可能角βが入射探触子１の発信角αより小さく設定されている。
【００１９】
また、入射探触子１は、その側方に位置する溶接部３０の全域に超音波を到達させる必要があるので、相対的に下方に向けて超音波を入射している。一方、受信探触子１０は、傾斜面に配置されているので、受信探触子１０と溶接部３０を結ぶ線と傾斜面とがなす角度は、入射探触子１と溶接部３０とを結ぶ線と梁材Ａの上面とがなす角より遙かに小さくなる。このため、この受信探触子１０は、接触させている傾斜面に、より近い方向から超音波を受信できるように、受信可能角βの設定される方向をより傾斜斜面側に大きく屈折させるように構成されている。
【００２０】
図２は、入射探触子１及び受信探触子１０の内部構造を示している。これら入射探触子１及び受信探触子１０は、その外殻をなす箱状のケーシング２，１１を有し、ケーシング２，１１の内部には、介在部材であるクサビ部材３，１２と、このクサビ部材３，１２の上面４，１３に取り付けられた発信素子６、受信素子１５が内蔵されている。ケーシング２，１１は、アルミニウム、銅、その他の導電金属によって、その上面が密閉され、下面が開放されるように形成されている。また、クサビ部材３，１２は、アクリル樹脂、ポリイミド樹脂等の樹脂で形成され、超音波を透過させている。クサビ部材３，１２の下面５，１４は検査対象の表面と密接に接触するように平坦にそれぞれ形成されている一方、その上面４，１３は、入射探触子１又は受信探触子１０の後部側が下側に向けて傾く傾斜面として形成されている。
【００２１】
入射探触子１に内蔵されたクサビ部材３の上面４は、水平線に対して形成される傾斜角θ１が比較的になだらかに形成されている一方で、受信探触子１０に内蔵されたクサビ部材１２の上面１３は、その傾斜角θ２が入射探触子１に比べ大きく形成されている。このため、受信素子１５の受信面１６は、発信素子６の発信面７に比べ前方に向けられている。
【００２２】
また、発信素子６及び受信素子１５は、水晶，圧電セラミックス材料等により形成されている。発信素子６は所定の軸方向に正負の電圧が印加されると伸縮により超音波を発生する逆圧電効果を奏する一方で、受信素子１５は、超音波を受信することで電圧を発生させる圧電効果を奏している。これらの作用によって、発信素子６は超音波を発生させ、また受信素子１５は電気信号を発信している。なお、受信素子１５の受信面１６の面積は、発信素子６の発信面７の面積より大きく形成されている。
【００２３】
以上のように入射探触子１及び受信探触子１０が構成されているので、超音波探傷装置は次のように作用する。
【００２４】
入射探触子１の超音波の発信方向及び受信探触子１０の受信方向は、各クサビ部材３，１２の上面４，１３の水平面に対する傾斜角θ１，θ２により設定される。傾斜角θ１，θ２が小さく形成されていれば検査対象の表面で超音波が屈折した場合、相対的に鉛直下方に向けて入射され、又は鉛直下方からの超音波を受信し、表面とのなす角度φ１，φ２が大きくなる。一方、上面４，１３の傾斜角θ１，θ２が大きく形成されていれば、検査対象の表面で超音波が屈折した際、相対的に表面により近い位置へ超音波を入射させ、又は表面により近い位置の超音波を受信でき、表面とのなす角度φ１，φ２が小さくなる。この超音波探傷装置では、入射探触子１に内蔵されたクサビ部材３の上面４の傾斜角θ１を小さく形成し、検査対象の表面とのなす角φ１を相対的に大きくして超音波を入射させている。一方、受信探触子１０に内蔵されたクサビ部材１２の上面１３の傾斜角θ２を大きく形成し、検査対象の表面とのなす角φ２が相対的に小さい方向からの超音波を取り込むようにしている。
【００２５】
また、入射探触子１の発信角αと受信探触子１０の受信可能角βとは、内蔵された発信素子６及び受信素子１５の大きさ、並びに超音波の波長により決定される。発信角α及び受信可能角βは、発信素子６及び受信素子１５が大きいほど小さくなり、超音波の波長が長いほど大きくなる。この超音波探傷装置では、入射探触子１が発した超音波を受信探触子１０で受信するため、超音波の波長によって入射探触子１と受信探触子１０の広がり角に差を設けることはできない。このため、入射探触子１に発信面７の面積の小さな発信素子６を内蔵させる一方で、受信探触子１０に、発信面７の面積より大きく形成された受信面１６を有する受信素子１５を内蔵させている。
【００２６】
このような入射探触子１と受信探触子１０との組み合わせにより、梁材Ａと台形状部材Ｂとの溶接部３０の欠陥は以下のようにして探傷される。
【００２７】
入射探触子１を溶接部３０の側方にて梁材Ａの上面に接触させる。この際、入射探触子１の先端側を溶接部３０に向けて配置する。一方、受信探触子１０を台形状部材Ｂの傾斜面に接触させる。受信探触子１０についてもその先端側を溶接部３０に向けて配置する。
【００２８】
両探触子１，１０をこのように配置した状態で、発信機２０を作動から入射探触子１に所定の電圧を印加して、内蔵された発信素子６から超音波を発信させる。この発信素子６は、受信素子１５に比し小さく形成されているため、この発信素子６からは、相対的に大きな発信角αの超音波が発信される。また、傾斜角θ１の小さく形成された上面４を有するクサビ部材３の上面に発信素子６が取り付けられているので、梁材Ａの表面となす角φ１が相対的に大きな方向に向けて超音波は入射される。これにより、溶接部３０の全域に超音波を伝達させることができる。
【００２９】
そして、受信探触子１０で、構造物の表面Ｃを伝達するラテラル波、溶け込み不良３１の上端３２で発生する回析波、溶け込み不良３１の下端３３で発生する回析波、並びに梁材Ａの下面Ｄで反射されるエコー波を受信する。上述のように、受信探触子１０に内蔵された受信素子１５は、傾斜角θ２の大きく形成された上面１３を有するクサビ部材１２に取り付けられて、受信面１６が受信探触子１０の前方へ向けられている。また、受信面１６の面積が発信面７の面積に比し、大きく形成されている。このため、受信探触子１０は、斜面部とのなす角φ２が小さい表面に近い方向で、しかも受信可能角βが小さい範囲の超音波のみを受信する。これにより、溶接部３０からの超音波のみを受信し、溶接部３０以外で発生する回析波やエコー波を取り込むことがない。
【００３０】
受信探触子１０で受信したラテラル波、回析波及びエコー波は受信素子１５で電気信号に変化され、受信機２１に送信される。この電気信号を受信した受信機２１は、この信号に対して所定の変換を行って、その下流に接続されたモニタ装置２２に送信し、対応する超音波の波形を映し出させている。
【００３１】
図３は、モニタ装置２２に映し出された波形を示している。図３の最も左側に現れている波形４０は、ラテラル波によるもので、左から２番目に現れている波形４１は、溶け込み不良３１の上端３２で発生した回析波によるものである。溶け込み不良３１の上端３２で発生した回析波による波形４１の右側直近に現れている波形４２は、溶け込み不良３１の下端３３で発生した回析波に対応している。そして、右端に現れている波形４３は、梁材Ａの下面Ｄで反射したエコー波に対応する波形である。このグラフにおいて、ラテラル波に対応する波形４０と、溶け込み不良３１の上端３２で発生した回析波に対応する波形４１の間隔５０は、梁材Ａの上面から溶け込み不良３１の上端３２までの深さを表している。また、２つの回析波に対応する波形４１，４２同士の間隔５１は、溶け込み不良３１の長さを表している。そして、溶け込み不良３１の下端３３で発生した回析波に対応する波形４２と、エコー波に対応する波形４３との間隔は５２溶け込み不良３１の下端３３から梁材Ａの下面Ｄまでの距離を表している。このように、当該超音波探傷装置を使用すれば、単に溶接部３０に欠陥があるか否かを検査するだけで無く、欠陥の位置と大きさをも特定することができる。図１に示す例であれば、溶け込み不良３１の長さＬ、梁材Ａの上面から溶け込み不良３１の上端３２までの距離Ｌ１、下端３３までの距離Ｌ２を正確に把握することができる。
【００３２】
図４は、この超音波探傷装置を使用して、他の構造物の溶接部を探傷している実施形態を示している。
【００３３】
この実施形態における検査対象である構造物は、鉛直に延びる平板Ｅの一面側に、水平に延びる他の平板Ｆの端面を突き合わせ、両部材Ｅ，Ｆが直角をなすようにして溶接された構造物である。この実施形態では、入射探触子６０を水平に配された平板Ｆの下面に接触させると共に、受信探触子６１を鉛直に延びる平板Ｅの一面側であって、水平に延びる平板Ｆの下方に接触させている。なお、この場合も入射探触子６０の先端を溶接部６５側へ向けて接触させると共に、受信探触子６１の先端も溶接部６５側へ向けて接触させる。
【００３４】
かかる構造物を探傷する場合に関しても、入射探触子６０から相対的に大きな発信角α２で超音波を構造物水平に延びる平板Ｆに入射させる一方、受信探触子６１は、発信角α２に比べて小さな受信可能角β２の範囲内で超音波を受信している。また、入射探触子６０から水平に延びる平板Ｆへは、接触させた下面とのなす角φ３が相対的に大きくなる方向へ超音波が入射される一方で、受信探触子６１へは、水平に延びる平板との接合面である一面側とのなす角φ４が小さく相対的にその表面に近い方向からの超音波を受信する。
【００３５】
なお、この実施形態にかかる構造物を探傷する場合、図１と図４との比較から明らかなように、受信探触子６１は、垂直に延びる平板Ｅの表面により近い方向から超音波を受信すると共に、受信可能角β２をより小さく形成しなければ、溶接部６５のみから超音波を受信することができなくなる。このため、この受信探触子６１では内蔵されたクサビ部材（不図示）の上面の傾斜角が、図１に示す受信探触子１０に内蔵されクサビ部材１２の上面１３の傾斜角より大きく形成され、受信面がより前方に大きく傾くように構成されている。また、受信可能角β２をより小さく形成するために、この受信探触子６１では、受信素子（不図示）の受信面の面積が、図１に示す受信探触子１０の受信面の面積より大きく形成されている。
【００３６】
なお、この実施形態では、受信探触子６１についてのみ、受信可能角β２、検査対象の表面とのなす角φ４が異なる探触子を選択したが、検査対象によっては、入射探触子６０を適宜選択し、又は入射探触子及び、受信探触子６１の双方を選択して使用してもよい。この際、発信角と受信可能角のみ、あるいは超音波を入射させる方向と受信する方向の双方のみが異なる探触子を選択してもよく、これらのいずれもが異なる探触子を選択してもよい。
【００３７】
このように、この超音波探傷装置では、互いに異なる発信角で、異なる方向に超音波を発信する入射探触子と、互いに異なる受信可能角で、異なる方向から超音波を受信する受信探触子をそれぞれ複数備えている。かかる入射探触子及び受信探触子の中から、検査対象に最も適した超音波を入射させる入射探触子及び超音波を受信する受信探触子を適宜選択して超音波探傷が行われる。
【００３８】
図５は、本発明の別の実施形態にかかる方法で、検査対象の超音波探傷を行う態様を示している。この実施の形態にかかる探傷方法では、部材同士が互いに直角に交差された状態で溶接された溶接部を検査対象としている。垂直に配置された縦板７０の一面側には、水平に配された横板７１の端面が溶接されている。これら両板材７０，７１の溶接部が検査対象である。この探傷方法では、入射探触子７２を横板７１の上側に位置する溶接ビード７５の表面に接触させ、溶接ビード７５から超音波を入射させている一方、受信探触子７３を横板７１の上方にて縦板７０の表面に接触させて、縦板７０を伝達した超音波を受信している。この実施形態においても、検査対象の表面である溶接ビード７５の表面と入射探触子７２から入射された超音波のなす角より、受信探触子７３により受信される超音波の方向と検査対象の表面がなす角が小さくなる探触子同士が組み合わせされている。
【００３９】
そして、この探傷方法に関しても、溶接ビード７５の表面及び縦板７０の表面を伝達するラテラル波、欠陥７７の上端で回析された回析波、欠陥７７の下端で回析された回析波（図５中、二点鎖線で示した矢印）、及び横板の下面で反射されたエコー波（図５中、実線で示した矢印）を解析して欠陥７７の位置及び長さが特定される。ここで、入射探触子７２は溶け込み不良等の欠陥７７と比較的接近した位置である溶接ビード７５の表面に接触されており、溶け込み不良等の欠陥７７と入射探触子７２との距離は、入射探触子と横板の下面との距離に比し相対的に短い。このため、欠陥７７の下端を回析する回析波が、横板の下面を反射するエコー波より先に受信され、図６に示すように、モニタには回析波８０がエコー波８１より確実に先に現れる。したがって、横板の上側からのみ探傷を行えば、欠陥７７の探傷を行うことができる。
【００４０】
このメリットに関し、図７及び図８に示す探傷方法と対比して説明する。
【００４１】
図７に示す探傷方法も、直角に交わるように縦板９０の片面に横板９１の端面を突き合わせて溶接した溶接部を探傷している。この探傷方法にあっては、入射探触子９２が溶接部からやや離れた位置にて横板９１の上面に接触されており、欠陥９７と入射探触子９２との距離が比較的離れている。このように配置された状態では、内在する欠陥９７が大きくその長さが長い場合、入射探触子９２−横板９１の下面−受信探触子９３の経路の距離（図７の実線で示した矢印）より、入射探触子９２−欠陥９７の下端−受信探触子９３の経路（図７の二点鎖線で示した矢印）の距離の方が長くなることもある。この場合、エコー波の方が回析波より先に受信探触子に受信される。このため、モニタには、図８に示すように、エコー波１００が回析波１０１より先に表示される。このような波形が測定されることがあると、波形１００，１０１のどの部分がエコー波１００で、どの部分が回析波１０１であるのか不明となり、正確な解析を行うことができない。
【００４２】
このため、横板９１の下側からの探傷も必要となる。すなわち、入射探触子９２を横板９１の下面に接触させると共に、この横板９１よりやや下方の位置にて、受信探触子９３を縦板９０の片面に接触させて、再び探傷を行う。そして、上側からの探傷において、モニタの画面の３番目に現れる波形及び４番目に現れる波形、並びに下側からの探傷において、モニタの画面の第２番目に現れる波形を総合的に分析することで、欠陥の位置、大きさを特定する。
【００４３】
このように、図７に示す探傷方法では、欠陥を特定するのに手間と時間を要するが、図５に示すように入射探触子７２を溶接ビード７５の表面に接触させて、溶接ビード７５の表面から超音波を入射させて探傷を行うことで、片側からの探傷のみで欠陥の位置大きさを正確に把握することができる。
【００４４】
なお、図５では、二つの部材が直角をなして溶接された溶接部を探傷する様子を示しているが、二つの部材が所定の角度をなして交差していれば、部材同士がなす角度は直角をなすものには限定されない。
【００４５】
【発明の効果】
以上、本発明によれば、超音波を入射させる方向及び発信角、並びに超音波を受信する方向と受信可能角を所定の範囲に特定しているので、平面形状の検査対象に限定されることなく複雑な形状を有する構造物について、きわめて容易に超音波探傷することができる。また、入射探触子及び受信探触子を検査対象に適応させて適宜選択可能としているので、種々の形状の構造物について超音波探傷を行える。
【００４６】
特に、所定の角度で交わる部材同士の溶接部を探傷する場合に、入射探触子を溶接ビードの表面に接触させて、超音波をこの溶接ビードの表面から入射すれば、一度の探傷で欠陥の位置大きさを正確に把握することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態にかかる超音波探傷装置を使用して構造物を探傷している一態様を示す図。
【図２】図１に示す超音波探傷装置に使用されている入射探触子及び受信探触子の内部構造を示す図。
【図３】図１に示す超音波探傷装置のモニタ装置に現れる波形の説明図。
【図４】図１に示す構造物とは別の構造物について超音波探傷を行う態様を示す図。
【図５】本発明の別の実施形態にかかる超音波探傷方法の態様を示す図。
【図６】図５に示す超音波探傷方法で探傷を行った場合のモニタに現れる波形の説明図。
【図７】図５に示す超音波探傷と別の態様で超音波探傷を行う態様を示す図。
【図８】図７に示す超音波探傷方法で探傷を行った場合のモニタに現れる波形の説明図。
【図９】従来から行われているＴＯＦＤ法で超音波探傷を行う態様を示す図。
【図１０】図９に示すＴＯＦＤ法で超音波探傷を行った場合のモニタに現れる波形の説明図。
【符号の説明】
１，６０，７２，９２　入射探触子
２，１１　ケーシング
３，１２　クサビ部材
４，１３　上面
６　発信素子
７　発信面
１０，６０，７３，９３　受信探触子
１５　受信素子
１６　受信面
２０　発信機
２１　受信機
２２　モニタ装置
３０，６５　溶接部（検査部位）
α，α２　発信角
β，β２　受信可能角
θ１，θ２　傾斜角
φ１，φ３　超音波が入射された方向と検査対象の表面がなす角
φ２，φ４　受信される超音波の方向と検査対象の表面がなす角[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic flaw detection apparatus and an ultrasonic flaw detection method in which an ultrasonic wave is incident on an inspection target with an incident probe, and the ultrasonic wave transmitted through the inspection target is received with a reception probe.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a TOFD (Time Of Flight Diffraction) method has been known as an ultrasonic inspection for inspecting a defect existing in an inspection target without destroying the inspection target. In the TOFD method, as shown in FIG. 9, an incident probe 110 for making an ultrasonic wave incident on an inspection target and a receiving probe 111 for receiving an ultrasonic wave are opposed to each other and brought into contact with the surface of the inspection object 112. The longitudinal probe ultrasonic wave is made incident on the inspection object 112 from the incident probe 110, and the diffracted waves generated at the upper end 114 and the lower end 115 of the intrinsic defect 113 are received by the receiving probe 111 so that the defect 113 is detected. It is a method of detecting flaws. In the TOFD method, a lateral wave propagating along the surface of the inspection object 112, diffraction waves 121 and 122 generated at the upper end 114 and lower end 115 of the defect 113, and an echo wave 123 reflected at the bottom surface of the inspection object 112 are The position and size of the defect can be accurately inspected based on the relationship between the time difference of propagation from the incident probe 110 to the receiving probe 111 and the speed of sound.
[0003]
Specifically, as shown in FIG. 6, a monitor device capable of displaying a waveform such as an oscilloscope includes a lateral wave 120, a diffraction wave 121 generated at the upper end of the defect, a diffraction wave 122 generated at the lower end of the defect, In addition, the echo wave 123 is projected. Then, the position and size of the defect are specified by analyzing the propagation time of each waveform.
[0004]
A plurality of prior arts have already been disclosed for such a nondestructive inspection method by the TOFD method (for example, see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-2002-139479 (paragraph numbers 0012 to 0013, FIG. 1, paragraph number 0003, FIG. 6)
[0006]
[Problems to be solved by the invention]
However, in the TOFD method, the inspection target needs to be formed in a planar shape, and both the incident probe and the receiving probe need to be arranged on the same plane. For this reason, it is impossible to detect internal defects by TOFD for a structure having a complicated shape such as a bridge girder. In recent years, a new non-destructive inspection method capable of inspecting a structure having a complicated shape such as a bridge girder without destroying an inspection object has been socially desired.
[0007]
The present invention has been made in order to meet such a demand, and an ultrasonic flaw detection apparatus and an ultrasonic flaw detection method capable of extremely easily flaw detection of an internal defect without destroying a test object having a complicated shape. The purpose is to provide.
[0008]
[Means for Solving the Problems]
In the present invention, in order to solve the above-mentioned problem, a transmission element for transmitting an ultrasonic wave, having a predetermined inclination angle with respect to the surface of the inspection target and having a transmission surface directed to the inspection site side of the inspection target, is incorporated. An incident probe that makes the ultrasonic wave incident on the inspection object at a transmission angle of a predetermined spread angle from the transmission element, forms a predetermined inclination angle with the surface of the inspection object, and has a receiving surface on the inspection site side. A receiving probe for receiving an ultrasonic wave which is directed from the incident probe and receives the ultrasonic wave transmitted through the inspection object and receives only the ultrasonic wave within a receivable angle which is a predetermined spread angle. And a tilt angle formed between the receiving surface and the surface of the inspection target is formed to be larger than a tilt angle formed between the transmission surface and the surface of the inspection target, so that the reception surface is relative to the transmission surface. If it is greatly inclined to the inspection site side To the receivable angle adopted a ultrasonic flaw detector that is smaller than the outgoing angle.
[0009]
Further, at a predetermined angle from the incident probe with respect to the surface of the inspection target, and at a transmission angle of a predetermined divergence angle, ultrasonic waves are incident toward the inspection site of the inspection target, the incident probe is A receiving probe that receives only ultrasonic waves within a range of an angle smaller than an angle formed between the incident ultrasonic wave and the surface of the inspection target and a receivable angle smaller than the transmission angle, The inspection object is inspected by the ultrasonic inspection method, which receives the ultrasonic wave transmitted from the probe and transmitted to the inspection object.
[0010]
According to the present invention, an ultrasonic wave is incident on a relatively wide range from an incident probe to an inspection target, and the ultrasonic wave reaches a portion to be detected without leakage. On the other hand, the receiving probe receives only ultrasonic waves in a direction relatively close to the surface of the contacted inspection target and within a smaller angle range. Accordingly, the receiving probe surely receives the ultrasonic waves that are incident from the incident probe and transmitted to the inspection target, not only for the inspection target formed flat but also for the inspection target having a complicated shape. In addition, since the receiving probe receives only ultrasonic waves transmitted from a limited area to be flaw-detected, it does not receive extra echo waves or diffracted waves and realizes high reliability.
[0011]
Further, from among a plurality of incident probes formed so that at least one of the inclination angle and the transmission angle is different from each other, an incident probe suitable for the inspection object is selected, and the incident probe is selected. The ultrasonic wave is incident by changing one or both of the angle formed with the surface of the inspection target and the transmission angle, and at least one of the inclination angle and the receivable angle is formed to be different from each other. From among the plurality of received probes, a receiving probe adapted to the inspection object is selected, and either one of the angle formed by the receiving probe and the surface of the inspection object or the receivable angle is selected. Or, by changing both, the ultrasonic wave which is incident from the incident probe and transmitted to the inspection object is received.
[0012]
Furthermore, when the welded part welded by crossing the members at a predetermined angle is the inspection target, the incident probe is brought into contact with the surface of the weld bead of the welded part, and the ultrasonic wave is incident. In addition to preventing the formation of a dead zone in the above-described invention, the flaw detection can be performed more efficiently by irradiating ultrasonic waves from the bead surface. That is, the diffraction wave from the defective portion existing in the welded portion is received by the receiving probe surely before the echo wave reflected from the back surface of the member. Therefore, the presence or absence of a defect can be determined by measurement from one side.
[0013]
By performing the ultrasonic inspection in this manner, an incident probe and a reception probe that are appropriate for the shape of the inspection object and the width of the range to be inspected are appropriately selected, and a highly reliable ultrasonic inspection is performed. It can be carried out.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015]
FIG. 1 shows a state where a weld 30 of two members A and B constituting a structure is flaw-detected using an ultrasonic flaw detector according to one embodiment of the present invention. As shown in FIG. 1, one member to be welded is a horizontally extending beam member A, and the other member is a trapezoidal member B having a slope formed to be divergent from one end to the other end. is there. In this embodiment, an ultrasonic flaw detector is used to detect a penetration defect of the welded portion 30 where the axial end face of the beam material A and the upper bottom face of the trapezoidal member B are butt-welded.
[0016]
The ultrasonic flaw detection apparatus includes an incident probe 1 for irradiating an ultrasonic wave to a structure to be inspected, and a reception probe for receiving an ultrasonic wave incident from the incident probe 1 and transmitting the structure. And a child 10. The incident probe 1 is in contact with the upper surface of the beam A, while the receiving probe 10 has a trapezoidal shape with the welding portion 30 positioned between the incident probe 1 and the receiving probe 10. The member B is in contact with the inclined surface. A transmitter 20 for applying a predetermined voltage to the incident probe 1 and transmitting ultrasonic waves from the incident probe 1 is connected to the incident probe 1 via a cable. On the other hand, the receiving probe 10 is connected via a cable to a receiver 21 that receives an electric signal corresponding to the received ultrasonic wave transmitted by the receiving probe 10. Furthermore, a monitor device 22 that displays a waveform corresponding to the electric signal received by the receiver 21 is connected to the receiver 21.
[0017]
In this ultrasonic flaw detector, a longitudinal wave is incident on the beam material A from the incident probe 1 and is transmitted at the upper end 32 and the lower end 33 of the penetration defect 31 which is transmitted along the surface C of the structure. Diffraction wave and the echo wave reflected by the lower surface D of the beam material A are received by the receiving probe 10 in contact with the trapezoidal member B, and the presence, the position, and the size of the penetration defect 31 are inspected. are doing. In this ultrasonic flaw detector, the incident probe 1 irradiates an ultrasonic wave from the built-in transmitting element with a transmission angle α of a predetermined spread angle to the beam material A, and the reception probe 10 It is configured to receive only ultrasonic waves transmitted within the range of the receivable angle β having an angle.
[0018]
Since the incident probe 1 is disposed on the upper surface of the beam material A, it is necessary to transmit the ultrasonic wave from the incident probe 1 at a wide angle in order to transmit the ultrasonic wave to the entire area of the welded portion 30. For this reason, in the incident probe 1, the transmitting element transmits the ultrasonic wave at the relatively large transmission angle α, and the ultrasonic wave reaches the entire area of the welded portion 30 without leakage. On the other hand, the receiving probe 10 needs to inspect only a defect existing in the welded portion 30. For this reason, in the receiving probe 10, the receivable angle β is set to be smaller than the transmitting angle α of the incident probe 1 so that the range of receiving the ultrasonic wave is limited to only the range of the welding portion 30.
[0019]
In addition, since the incident probe 1 needs to reach the entire area of the welded portion 30 located on the side of the incident probe 1, the ultrasonic probe is incident relatively downward. On the other hand, since the receiving probe 10 is disposed on the inclined surface, the angle between the line connecting the receiving probe 10 and the welded portion 30 and the inclined surface is determined by the angle between the incident probe 1 and the welded portion 30. It is much smaller than the angle between the connecting line and the upper surface of the beam material A. For this reason, the receiving probe 10 refracts the direction in which the receivable angle β is set to a greater angle toward the inclined surface so that the ultrasonic wave can be received from a direction closer to the inclined surface in contact. Is configured.
[0020]
FIG. 2 shows the internal structure of the incident probe 1 and the receiving probe 10. Each of the incident probe 1 and the receiving probe 10 has box-shaped casings 2 and 11 forming outer shells thereof, and inside the casings 2 and 11, wedge members 3 and 12, which are interposed members, The transmitting element 6 and the receiving element 15 attached to the upper surfaces 4 and 13 of the wedge members 3 and 12 are built in. The casings 2 and 11 are formed of aluminum, copper, or another conductive metal so that the upper surface is closed and the lower surface is open. The wedge members 3 and 12 are formed of a resin such as an acrylic resin or a polyimide resin, and transmit ultrasonic waves. The lower surfaces 5 and 14 of the wedge members 3 and 12 are formed flat so as to be in close contact with the surface to be inspected, while the upper surfaces 4 and 13 are formed on the incident probe 1 or the receiving probe 10. The rear side is formed as an inclined surface inclined downward.
[0021]
The upper surface 4 of the wedge member 3 incorporated in the incident probe 1 has a relatively gentle inclination angle θ1 formed with respect to the horizontal line, while the wedge embedded in the reception probe 10 is formed. The upper surface 13 of the member 12 is formed so that its inclination angle θ2 is larger than that of the incident probe 1. For this reason, the receiving surface 16 of the receiving element 15 is directed more forward than the transmitting surface 7 of the transmitting element 6.
[0022]
The transmitting element 6 and the receiving element 15 are made of quartz, piezoelectric ceramic material, or the like. The transmitting element 6 has an inverse piezoelectric effect of generating ultrasonic waves by expansion and contraction when positive and negative voltages are applied in a predetermined axial direction, while the receiving element 15 has a piezoelectric effect of generating a voltage by receiving ultrasonic waves. Is playing. By these actions, the transmitting element 6 generates an ultrasonic wave, and the receiving element 15 transmits an electric signal. Note that the area of the receiving surface 16 of the receiving element 15 is formed larger than the area of the transmitting surface 7 of the transmitting element 6.
[0023]
Since the incident probe 1 and the receiving probe 10 are configured as described above, the ultrasonic flaw detector operates as follows.
[0024]
The transmitting direction of the ultrasonic wave of the incident probe 1 and the receiving direction of the receiving probe 10 are set by the inclination angles θ1 and θ2 of the upper surfaces 4 and 13 of the wedge members 3 and 12 with respect to the horizontal plane. If the ultrasonic waves are refracted on the surface of the inspection object if the inclination angles θ1 and θ2 are formed to be small, the ultrasonic waves are incident relatively vertically downward, or receive the ultrasonic waves from the vertical lower direction, and form with the surface. The angles φ1 and φ2 increase. On the other hand, if the inclination angles θ1 and θ2 of the upper surfaces 4 and 13 are formed to be large, when the ultrasonic waves are refracted on the surface to be inspected, the ultrasonic waves are made to enter a position relatively closer to the surface or closer to the surface. The ultrasonic waves at the position can be received, and the angles φ1 and φ2 formed with the surface are reduced. In this ultrasonic flaw detector, the inclination angle θ1 of the upper surface 4 of the wedge member 3 incorporated in the incident probe 1 is formed to be small, and the angle φ1 formed with the surface of the inspection object is made relatively large to generate ultrasonic waves. It is incident. On the other hand, the inclination angle θ2 of the upper surface 13 of the wedge member 12 incorporated in the receiving probe 10 is formed large so that the angle φ2 between the upper surface 13 and the surface to be inspected takes in ultrasonic waves from a relatively small direction. I have.
[0025]
The transmission angle α of the incident probe 1 and the receivable angle β of the reception probe 10 are determined by the sizes of the built-in transmitting element 6 and receiving element 15 and the wavelength of the ultrasonic wave. The transmission angle α and the receivable angle β decrease as the transmission element 6 and the reception element 15 increase, and increase as the wavelength of the ultrasonic wave increases. In this ultrasonic flaw detector, the ultrasonic wave emitted by the incident probe 1 is received by the receiving probe 10, so that the difference in the spread angle between the incident probe 1 and the receiving probe 10 depends on the wavelength of the ultrasonic wave. It cannot be provided. Therefore, while the transmitting element 6 having a small area of the transmitting surface 7 is built in the incident probe 1, the receiving element 15 having the receiving surface 16 formed larger than the area of the transmitting surface 7 is provided in the receiving probe 10. Is built in.
[0026]
With such a combination of the incident probe 1 and the receiving probe 10, a defect in the welded portion 30 between the beam A and the trapezoidal member B is detected as follows.
[0027]
The incident probe 1 is brought into contact with the upper surface of the beam A on the side of the welded portion 30. At this time, the distal end side of the incident probe 1 is arranged facing the welded portion 30. On the other hand, the receiving probe 10 is brought into contact with the inclined surface of the trapezoidal member B. The distal end of the receiving probe 10 is also arranged facing the welded portion 30.
[0028]
With the two probes 1 and 10 arranged in this manner, a predetermined voltage is applied to the incident probe 1 from operation of the transmitter 20 so that the built-in transmitting element 6 transmits ultrasonic waves. Since the transmitting element 6 is formed smaller than the receiving element 15, the transmitting element 6 transmits an ultrasonic wave having a relatively large transmitting angle α. Further, since the transmitting element 6 is mounted on the upper surface of the wedge member 3 having the upper surface 4 formed with a small inclination angle θ1, the ultrasonic wave is directed toward the direction in which the angle φ1 formed with the surface of the beam material A is relatively large. Is incident. Thereby, ultrasonic waves can be transmitted to the entire area of the welded portion 30.
[0029]
Then, in the receiving probe 10, a lateral wave transmitted on the surface C of the structure, a diffraction wave generated at the upper end 32 of the poor penetration 31, a diffraction wave generated at the lower end 33 of the poor penetration 31, and the beam A Receive the echo wave reflected by the lower surface D of the first. As described above, the receiving element 15 built in the receiving probe 10 is attached to the wedge member 12 having the upper surface 13 formed with a large inclination angle θ2, and the receiving surface 16 is located in front of the receiving probe 10. Is turned to. Also, the area of the receiving surface 16 is formed larger than the area of the transmitting surface 7. For this reason, the receiving probe 10 receives only ultrasonic waves in a direction close to the surface where the angle φ2 formed with the slope portion is small and in a range where the receivable angle β is small. Thus, only the ultrasonic waves from the welded portion 30 are received, and diffraction waves and echo waves generated outside the welded portion 30 are not taken in.
[0030]
Lateral waves, diffraction waves and echo waves received by the receiving probe 10 are converted into electric signals by the receiving element 15 and transmitted to the receiver 21. The receiver 21 that has received the electric signal performs a predetermined conversion on the signal, transmits the signal to a monitor device 22 connected downstream thereof, and displays a corresponding ultrasonic waveform.
[0031]
FIG. 3 shows a waveform displayed on the monitor device 22. The waveform 40 appearing on the leftmost side in FIG. 3 is due to a lateral wave, and the waveform 41 appearing second from the left is due to a diffraction wave generated at the upper end 32 of the poor penetration 31. A waveform 42 appearing immediately to the right of a waveform 41 due to a diffraction wave generated at the upper end 32 of the poor penetration 31 corresponds to a diffraction wave generated at the lower end 33 of the poor penetration 31. The waveform 43 appearing on the right end is a waveform corresponding to the echo wave reflected on the lower surface D of the beam material A. In this graph, the interval 50 between the waveform 40 corresponding to the lateral wave and the waveform 41 corresponding to the diffraction wave generated at the upper end 32 of the poor penetration 31 is the depth from the upper surface of the beam material A to the upper end 32 of the poor penetration 31. It represents the degree. The interval 51 between the waveforms 41 and 42 corresponding to the two diffraction waves indicates the length of the penetration failure 31. The interval between the waveform 42 corresponding to the diffraction wave generated at the lower end 33 of the poor penetration 31 and the waveform 43 corresponding to the echo wave is the distance from the lower end 33 of the poor penetration 31 to the lower surface D of the beam A. Represents. As described above, by using the ultrasonic flaw detector, it is possible to not only inspect whether or not the welded portion 30 has a defect but also specify the position and the size of the defect. In the example shown in FIG. 1, the length L of the penetration defect 31, the distance L1 from the upper surface of the beam material A to the upper end 32 of the penetration defect 31, and the distance L2 to the lower end 33 can be accurately grasped.
[0032]
FIG. 4 shows an embodiment in which the ultrasonic flaw detector is used to detect a flaw in a weld of another structure.
[0033]
The structure to be inspected in this embodiment has a structure in which an end surface of another horizontally extending flat plate F is abutted against one surface side of a vertically extending flat plate E, and both members E and F are welded so as to form a right angle. Things. In this embodiment, the incident probe 60 is brought into contact with the lower surface of the horizontally arranged flat plate F, and the receiving probe 61 is located on one side of the vertically extending flat plate E and below the horizontally extending flat plate F. Contact. In this case as well, the tip of the incident probe 60 is brought into contact with the welding portion 65 side, and the tip of the receiving probe 61 is also brought into contact with the welding portion 65 side.
[0034]
Also in the case of flaw detection of such a structure, ultrasonic waves are incident on the flat plate F extending horizontally from the incident probe 60 at a relatively large transmission angle α2, while the reception probe 61 has a transmission angle α2. Ultrasonic waves are received within a smaller receivable angle β2. Also, while ultrasonic waves are incident on the flat plate F extending horizontally from the incident probe 60 in a direction in which the angle φ3 between the contact probe and the lower surface becomes relatively large, the receiving probe 61 receives An angle φ4 formed between the flat surface extending horizontally and the one surface which is the joining surface is small, and the ultrasonic wave is received from a direction relatively close to the surface.
[0035]
When the structure according to this embodiment is to be inspected, the receiving probe 61 receives the ultrasonic wave from a direction closer to the surface of the vertically extending flat plate E, as is apparent from a comparison between FIG. 1 and FIG. At the same time, unless the receivable angle β2 is formed smaller, the ultrasonic wave cannot be received only from the welded portion 65. For this reason, the inclination angle of the upper surface of the wedge member (not shown) incorporated in the receiving probe 61 is formed larger than the inclination angle of the upper surface 13 of the wedge member 12 incorporated in the receiving probe 10 shown in FIG. The receiving surface is configured to be more greatly inclined forward. Further, in order to form the receivable angle β2 smaller, in the receiving probe 61, the area of the receiving surface of the receiving element (not shown) is larger than the area of the receiving surface of the receiving probe 10 shown in FIG. It is formed large.
[0036]
In this embodiment, only the receiving probe 61 has a receivable angle β2 and a probe having an angle φ4 different from the surface of the object to be inspected. However, depending on the object to be inspected, the incident probe 60 may be different. The selection may be made as appropriate, or both the incident probe and the reception probe 61 may be selected and used. At this time, a probe may be selected in which only the transmission angle and the receivable angle, or only the direction in which the ultrasonic wave is incident and the direction in which the ultrasonic wave is received are different, and a probe in which any of these is different may be selected. Is also good.
[0037]
Thus, in this ultrasonic flaw detector, an incident probe that transmits ultrasonic waves in different directions at different transmission angles, and a reception probe that receives ultrasonic waves from different directions at different receivable angles. , Respectively. Ultrasonic flaw detection is performed by appropriately selecting an incident probe that receives the most suitable ultrasonic wave for the inspection target and a receiving probe that receives the ultrasonic wave from the incident probe and the receiving probe. .
[0038]
FIG. 5 shows an embodiment in which ultrasonic inspection of an inspection object is performed by a method according to another embodiment of the present invention. In the flaw detection method according to this embodiment, a welded portion welded in a state where members are crossed at right angles to each other is to be inspected. An end face of a horizontally arranged horizontal plate 71 is welded to one surface side of the vertically arranged vertical plate 70. The welded portions of these two plate members 70 and 71 are to be inspected. In this flaw detection method, the incident probe 72 is brought into contact with the surface of the weld bead 75 located above the horizontal plate 71, and ultrasonic waves are incident from the weld bead 75, while the receiving probe 73 is connected to the horizontal plate 71. The ultrasonic wave transmitted through the vertical plate 70 is received by being brought into contact with the surface of the vertical plate 70 above. Also in this embodiment, the direction of the ultrasonic wave received by the receiving probe 73 and the angle of the ultrasonic wave received from the incident probe 72 and the surface of the weld bead 75, which is the surface to be inspected, and the inspection object The probes whose surface forms a smaller angle are combined with each other.
[0039]
As for this flaw detection method, a lateral wave transmitted on the surface of the weld bead 75 and the surface of the vertical plate 70, a diffracted wave diffracted at the upper end of the defect 77, and a diffracted wave diffracted at the lower end of the defect 77. (Arrows shown by two-dot chain lines in FIG. 5) and echo waves reflected by the lower surface of the horizontal plate (arrows shown by solid lines in FIG. 5) are analyzed to determine the position and length of the defect 77. You. Here, the incident probe 72 is in contact with the surface of the weld bead 75 at a position relatively close to the defect 77 such as poor penetration, and the distance between the defect 77 such as poor penetration and the incident probe 72 is Is relatively short as compared with the distance between the incident probe and the lower surface of the horizontal plate. For this reason, a diffracted wave diffracted at the lower end of the defect 77 is received before an echo wave reflected on the lower surface of the horizontal plate, and as shown in FIG. Will definitely appear first. Therefore, if flaw detection is performed only from the upper side of the horizontal plate, flaw detection for the defect 77 can be performed.
[0040]
This advantage will be described in comparison with the flaw detection method shown in FIGS.
[0041]
The flaw detection method shown in FIG. 7 also performs flaw detection on a welded portion where the end face of the horizontal plate 91 is abutted against one surface of the vertical plate 90 so as to intersect at right angles. In this flaw detection method, the incident probe 92 is in contact with the upper surface of the horizontal plate 91 at a position slightly away from the welded portion, and the distance between the defect 97 and the incident probe 92 is relatively large. I have. In this arrangement, if the intrinsic defect 97 is large and its length is long, the distance between the path of the incident probe 92, the lower surface of the horizontal plate 91, and the path of the receiving probe 93 (shown by a solid line in FIG. 7). In some cases, the distance between the input probe 92, the lower end of the defect 97, and the path of the receiving probe 93 (arrow indicated by a two-dot chain line in FIG. 7) may be longer than that of the arrow. In this case, the echo wave is received by the receiving probe before the diffraction wave. Therefore, the echo wave 100 is displayed on the monitor before the diffraction wave 101, as shown in FIG. If such a waveform is measured, it becomes unknown which part of the waveforms 100 and 101 is the echo wave 100 and which part is the diffraction wave 101, and accurate analysis cannot be performed.
[0042]
Therefore, flaw detection from below the horizontal plate 91 is also required. That is, the incident probe 92 is brought into contact with the lower surface of the horizontal plate 91, and the receiving probe 93 is brought into contact with one surface of the vertical plate 90 at a position slightly below the horizontal plate 91, and the flaw detection is performed again. . Then, in the flaw detection from above, the third and fourth waveforms appearing on the monitor screen, and in the flaw detection from below, the second waveform appearing on the monitor screen are comprehensively analyzed. And the position and size of the defect.
[0043]
As described above, in the flaw detection method shown in FIG. 7, it takes time and effort to specify a defect. However, as shown in FIG. 5, the incident probe 72 is brought into contact with the surface of the The flaw detection is performed by irradiating ultrasonic waves from the surface of the device, whereby the position and size of the defect can be accurately grasped only by flaw detection from one side.
[0044]
FIG. 5 shows a state in which the two members detect a welded portion welded at a right angle. However, if the two members intersect at a predetermined angle, the angle formed by the members is determined. Is not limited to a right angle.
[0045]
【The invention's effect】
As described above, according to the present invention, since the direction in which the ultrasonic wave is incident and the transmission angle, and the direction in which the ultrasonic wave is received and the receivable angle are specified within a predetermined range, the present invention is limited to the planar shape to be inspected. Ultrasonic flaw detection can be very easily performed on a structure having a complicated shape. In addition, since the incident probe and the receiving probe can be appropriately selected according to the object to be inspected, ultrasonic inspection can be performed on structures having various shapes.
[0046]
In particular, when flaw detection is performed on a weld between members that intersect at a predetermined angle, if the incident probe is brought into contact with the surface of the welding bead and ultrasonic waves are incident from the surface of the welding bead, a defect can be detected by one flaw detection. The size of the position can be accurately grasped.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment in which a structure is inspected using an ultrasonic inspection device according to an embodiment of the present invention.
FIG. 2 is a diagram showing the internal structure of an incident probe and a receiving probe used in the ultrasonic flaw detector shown in FIG. 1;
FIG. 3 is an explanatory diagram of waveforms appearing on a monitor of the ultrasonic flaw detector shown in FIG. 1;
FIG. 4 is a diagram showing a mode in which ultrasonic testing is performed on a structure different from the structure shown in FIG. 1;
FIG. 5 is a diagram showing an aspect of an ultrasonic flaw detection method according to another embodiment of the present invention.
6 is an explanatory diagram of waveforms appearing on a monitor when flaw detection is performed by the ultrasonic flaw detection method shown in FIG. 5;
FIG. 7 is a diagram showing a mode in which ultrasonic testing is performed in another mode than the ultrasonic testing shown in FIG. 5;
8 is an explanatory diagram of waveforms appearing on a monitor when flaw detection is performed by the ultrasonic flaw detection method shown in FIG. 7;
FIG. 9 is a diagram showing a mode in which ultrasonic flaw detection is performed by a conventional TOFD method.
FIG. 10 is an explanatory diagram of waveforms appearing on a monitor when ultrasonic flaw detection is performed by the TOFD method shown in FIG. 9;
[Explanation of symbols]
1,60,72,92 Incident probe
2,11 casing
3,12 wedge members
4,13 Upper surface
6 Transmitting element
7 Calling surface
10,60,73,93 Receiving probe
15 receiving element
16 Receiving surface
20 transmitter
21 Receiver
22 Monitoring equipment
30,65 welded part (inspection part)
α, α2 Transmission angle
β, β2 Receivable angle
θ1, θ2 tilt angle
φ1, φ3 Angle between the direction of incidence of ultrasonic wave and the surface of inspection object
φ2, φ4 Angle between direction of received ultrasonic wave and surface of inspection object

Claims

A transmitting element for transmitting ultrasonic waves having a predetermined inclination angle with respect to the surface of the inspection object and having a transmission surface directed toward the inspection site side of the inspection object is built in, and a transmission angle of a predetermined spread angle from the transmission element is included. An incident probe that makes the ultrasonic wave incident on the inspection target,
A receiving element that receives an ultrasonic wave transmitted from the incident probe and transmitted from the incident probe with the receiving surface directed to the inspection site side at a predetermined inclination angle with the surface of the inspection target is built in. And a receiving probe that receives only ultrasonic waves within a receivable angle that is a predetermined spread angle,
An inclination angle between the receiving surface and the surface of the inspection object is formed to be larger than an inclination angle between the transmission surface and the surface of the inspection object, and the reception surface is relatively closer to the inspection site than the transmission surface. While being greatly inclined to the side,
An ultrasonic flaw detector wherein the receivable angle is formed smaller than the transmission angle.

At least one of the inclination angle and the transmission angle is formed so as to be different from each other, and includes a plurality of incident probes selected according to an inspection object, and at least one of the inclination angle or the receivable angle. The ultrasonic flaw detector according to claim 1, further comprising a plurality of receiving probes that are formed so as to be different from each other and that are selected according to the inspection target.

At a predetermined angle with respect to the surface of the inspection target from the incident probe, and, at a transmission angle of a predetermined spread angle, the ultrasonic wave is directed toward the inspection site of the inspection target,
A receiving probe that receives only ultrasonic waves within an angle range smaller than the angle formed between the ultrasonic wave incident on the incident probe and the surface of the inspection object and within a receivable angle smaller than the transmission angle. An ultrasonic flaw detection method, comprising: receiving an ultrasonic wave incident on the probe from the incident probe and transmitting the inspection object.

Corresponding to the inspection object, at least one of the angle formed with the surface of the inspection object or the transmission angle is changed and ultrasonic waves are incident from the incident probe, and corresponding to the inspection object. By changing at least one of the angle formed with the surface of the inspection target and the receivable angle, the ultrasonic wave transmitted from the incident probe and transmitted through the inspection target is received by the reception probe. The ultrasonic flaw detection method according to claim 3, wherein:

The inspection target is a welded portion welded by crossing members at a predetermined angle, and the incident probe is brought into contact with a surface of a weld bead of the welded portion and the ultrasonic wave is incident. The ultrasonic flaw detection method according to claim 3 or 4, wherein: