JP4175762B2

JP4175762B2 - Ultrasonic flaw detector

Info

Publication number: JP4175762B2
Application number: JP2000144037A
Authority: JP
Inventors: 泰治平澤; 一朗古村; 敏長井
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2000-05-16
Filing date: 2000-05-16
Publication date: 2008-11-05
Anticipated expiration: 2020-05-16
Also published as: JP2001324484A

Description

【０００１】
【発明の属する技術分野】
本発明は、溶接構造物等の水浸法による欠陥探傷検査等に適用される超音波探傷装置に係り、特に薄板あるいは極厚板あるいは曲面形状などの特殊な形状、さらに複雑な溶接部の形状を有する被検査対象部位等に対して全体の欠陥有無およびその寸法測定を高速かつ高精度で測定することができる超音波探傷装置に関するものである。
【０００２】
【従来の技術】
超音波探傷法による各種金属材料の欠陥検査法としては、一般に、１個の超音波探触子を用いて超音波を送受信する超音波パルス反射法が広く用いられている。この方法は、欠陥からの反射波を検出し、欠陥の位置および大きさを測定する方法であり、例えば非破壊検査便覧（日本非破壊検査協会編、日刊工業新聞社発行）などに記載されている。
【０００３】
また、２個の探触子を検査対象部位である溶接部の溶接線方向に直角に溶接部を挟んで対向配置させ、その２個の探触子を同時に溶接線に対して直角方向に機械走査する方法も提案されている。この方法は、欠陥先端からの回折波、底面反射波などの情報から、その欠陥の位置および大きさを測定する方法である。それらは一般にＴＯＦＤ法（ＴｉｍｅｏｆＦｒｉｇｈｔＤｉｆｆｒａｃｔｉｏｎＴｅｃｈｎｉｑｕｅ）と呼ばれ、英国のＢＳ（ＢｒｉｔｉｓｈＳｔａｎｄａｒｄ）規格（１９９２年）などに記載されている。
【０００４】
一方、複数の振動子を配列したアレイ型超音波探触子を用いた欠陥検査法も提案されている（例えば「超音波探傷試験ＩＩＩ」：日本非破壊検査協会、１９８９年）。この方法は、アレイ型超音波探触子を被検査対象物に直接またはアクリル製のウエッジを介して超音波送受信を行い、欠陥の検出、寸法測定などを行う方法である。このアレイ型超音波探傷装置に関しては、例えば特開平９−２５７７６３号公報、特開平９−２５７７７４号公報などにより、各振動子を時間差により個々に順次に超音波の送受信を行わせる電子的走査を利用する技術が開示されている。
【０００５】
【発明が解決しようとする課題】
しかしながら、上述した１個の超音波探触子を用いて超音波を送受信する超音波パルス反射法を水浸法で行う場合には、溶接線に平行に発生する欠陥に対しては探触子を溶接線に対して直角方向に設置し、その方向に機械走査による探傷を行う必要があり、機械走査の移動時の位置ずれや被検体との距離が一定とならないなどの恐れがあり、また、欠陥情報を正しく収集できず機器の健全性評価上好ましくない等の問題がある。
【０００６】
また、欠陥寸法測定として一般に用いられている上述したＴＯＦＤ法においては、２個の探触子を溶接線を挟んで対向配置し、その２個の探触子を同時に溶接線に対して直角方向に機械走査させて欠陥情報を収集し、寸法測定を行うことから、被検体の板厚や形状が異なるごとに振動子角度等が異なる探触子に交換して、最適条件を求めて探傷する必要が生じる。さらに、前記パルス反射法と同様に、探触子の機械走査による移動誤差が生じる恐れがあり、機器の健全性評価上好ましくない。また、溶接部にシーニング加工が施されている部位の検査においては、ＴＯＦＤ法による欠陥の寸法測定において基準となる表面波の伝播時間が形状に依存して変化するため、欠陥の寸法測定上誤差が生じる恐れがある。
【０００７】
さらに、従来のアレイ型超音波探触子を用いた欠陥検査法においては電子的走査を行っているものの、各振動子により個々に順次に超音波の送受信を行わせるものであるため探傷速度や精度に一定の制限がある。
【０００８】
本発明は、このような事情に鑑みてなされたものであり、検査対象部位の形状、板厚などに応じて、アレイ型超音波探触子の１個または複数の振動子を超音波送信用振動子および受信用振動子をそれぞれ１組の振動子群として適正に選択し、電子的走査により探傷屈折角を任意に設定しながら最適探傷屈折角を求めることができ、また送信用探触子群と受信用探触子群の配置、電子走査方法など、種々の探傷条件を最適化することができ、この最適条件下で被検体を探傷することが可能で、超音波検出信号から欠陥情報を適正に収集することができ、それにより検査対象部位の形状、寸法などに拘らずに欠陥の有無、寸法等を高速かつ高精度で適正に測定することができる超音波探傷方法および超音波探傷装置を提供することを目的としている。
【０００９】
【課題を解決するための手段】
前記の目的を達成するため、請求項１の発明では、複数の振動子を配列しその任意の１個または複数の振動子を超音波送信用振動子および超音波受信用振動子として選択できるアレイ型超音波探触子を被検査対象部位の表面に設置する手段と、前記アレイ型超音波探触子の１または複数の振動子を超音波送信用振動子および超音波受信用振動子として選択する手段と、前記選択された振動子群を用いて被検査対象部位の所定位置に超音波ビームを集束または偏向させる手段と、前記超音波送信用振動子および超音波受信用振動子の電子的走査を行わせる手段と、この電子的走査によって検出された超音波波形に基づいて欠陥信号を抽出し、前記アレイ型超音波探触子の電子的走査位置に対する欠陥信号の振幅値分布を用いて欠陥位置および大きさを算出する手段と、この計測結果を出力する手段とを備えたことを特徴とする超音波探傷装置を提供する。
【００１４】
請求項１の発明では、複数の振動子を配列しその任意の１個または複数の振動子を超音波送信用振動子および超音波受信用振動子として選択できるアレイ型超音波探触子を被検査対象部位の表面に設置する手段と、前記アレイ型超音波探触子の１または複数の振動子を超音波送信用振動子および超音波受信用振動子として選択する手段と、前記選択された振動子群を用いて被検査対象部位の所定位置に超音波ビームを集束または偏向させる手段と、前記超音波送信用振動子および超音波受信用振動子の電子的走査を行わせる手段と、この電子的走査によって検出された超音波波形に基づいて欠陥信号を抽出し、前記アレイ型超音波探触子の電子的走査位置に対する欠陥信号の振幅値分布を用いて欠陥位置および大きさを算出する手段と、この計測結果を出力する手段とを備えたことを特徴とする超音波探傷装置を提供する。
【００１５】
請求項２の発明では、請求項１記載の超音波探傷装置において、アレイ型超音波探触子と被検査対象部位との距離、接触媒質の音速、検査対象部位の板厚およびその音速ならびに探傷屈折角に基づいて超音波送信用振動子と超音波受信用探触子との間隔を設定し、その超音波送信用振動子および超音波受信用振動子の数を一定に保持した状態で電子的走査を行わせる手段を備えたことを特徴とする音波探傷装置を提供する。
【００１６】
請求項３の発明では、請求項１または２記載の超音波探傷装置において、超音波送信用振動子および超音波受信用振動子の探傷屈折角を互いに同一として、超音波主ビームの交点を被検査対象部位の底面から表面に亘って連続的に移動させる手段を備えたことを特徴とする超音波探傷装置を提供する。
【００１７】
請求項４の発明では、請求項１から３までのいずれかに記載の超音波探傷装置において、アレイ型超音波探触子の被検査対象部位に対する設置位置を、前記アレイ型超音波探触子と前記被検査対象部位との距離、前記被検査対象部位を覆う水その他の接触媒質の音速、前記被検査対象部位の板厚およびその音速、ならびに前記被検査対象探傷部位への探傷屈折角に基づいて設定する手段を備えたことを特徴とする超音波探傷装置を提供する。
【００１８】
請求項５の発明では、請求項１から４までのいずれかに記載の超音波探傷装置において、被検査対象部位を溶接構造物とし、その溶接線に対してアレイ型超音波探触子の振動子配列方向を直角方向に設定して溶接線方向に進行させながら、超音波送受信時に得られた超音波波形データをオンラインで画像表示する手段と、その画像に基づいて被検査対象部位の全体に対する欠陥位置および寸法を測定する手段とを備えたことを特徴とする超音波探傷装置を提供する。
【００１９】
請求項６の発明では、請求項１から５までのいずれかに記載の超音波探傷装置において、アレイ型超音波探触子の振動子を２組の振動子群に分け、その１組の振動子群は送信用として被検査部位の側方に配置されて斜角探傷を電子的走査により行うものとし、他の組の振動子群は受信用として前記被検査対象部位の欠陥発生が想定される位置の真上近傍に設置されて欠陥先端からの回折波を検出するものであることを特徴とする超音波探傷装置を提供する。
【００２０】
請求項７の発明では、請求項１から６までのいずれかに記載の超音波探傷装置において、アレイ型超音波探触子の中から選択された１組の振動子群を使用して被検査対象部位の底部に向って超音波ビームを扇形状に集束または偏向する電子的走査を行わせる手段と、欠陥からの反射波の振幅値が最大となる屈折角を求める手段と、その屈折角を保持した状態での電子的走査によって得られた超音波波形情報から欠陥の位置および寸法を求める手段とを備えたことを特徴とする超音波探傷装置を提供する。
【００２１】
請求項８の発明では、請求項１から７までのいずれかに記載の超音波探傷装置において、アレイ型超音波探触子を被検査対象部位の外側に設置した状態における探触子側表面に発生する欠陥の探傷に際し、１組の振動子群を電子的走査による超音波送受用として適用し、この振動子群により送受信される超音波ビームを被検材の底面に反射させて被検査対象部位の表面の欠陥に入射させる１回反射法による探傷を可能とする手段を備えたことを特徴とする超音波探傷装置を提供する。
【００２２】
請求項９の発明では、請求項１から８までのいずれかに記載の超音波探傷装置において、被検査対象部位が構造物の溶接部で、その溶接線に沿う方向に発生する欠陥を探傷するものであり、アレイ型超音波探触子の各振動子の配列方向を前記溶接線方向に対して直角方向に設定する手段と、前記アレイ型超音波探触子を前記被検査対象部位の表面に対して平行に移動させる手段と、超音波入射方向を前記被検査対象部位の表面に対して垂直方向に設定する手段と、この状態を保持しつつ前記アレイ型超音波探触子を前記溶接線方向に移動させるとともに得られる欠陥信号の振幅値分布に基づいて欠陥の位置および寸法を測定する手段とを備えたことを特徴とする超音波探傷装置を提供する。
【００２３】
請求項１０の発明では、請求項１から９までのいずれかに記載の超音波探傷装置において、被検査対象部位が構造物の溶接部で、その溶接線に対して垂直方向に発生する欠陥を探傷するものであり、アレイ型超音波探触子を前記被検査対象部位の表面に対して傾斜させる手段を備えたことを特徴とする超音波探傷装置を提供する。
【００２４】
【発明の実施の形態】
以下、本発明の実施形態について、図面を参照して説明する。
【００２５】
第１実施形態（図１、図２）
図１は本発明に係る超音波探傷装置の実施形態を示す機能ブロック図であり、図２は図１に示したアレイ型超音波探触子を拡大して示す縦断面図である。
【００２６】
この超音波探傷装置は図１に示すように、溶接部１ａを有する構造物を被検査対象部位１とし、この被検査対象部位１の溶接部１ａ近傍に存在する欠陥１ｂの検査を行う場合に適用するものである。アレイ型超音波探触子２は複数の振動子Ａ（１）…Ａ（ｎ）を有し、例えば水を接触媒質Ｃとして検査対象部位１の外側に一定距離離間して配置され、振動子Ａ（１）…Ａ（ｎ）の配列方向が溶接部１ａの溶接線と直交する方向に沿う状態で設置される。
【００２７】
本実施形態では、アレイ型超音波探触子２を適正な位置に設置する手段としてセンサ保持機構３を有し、このセンサ保持機構３は駆動機構４によって溶接線方向あるいはこれと直行する方向等に移動できるようになっている。この駆動機構４の移動量、移動方向等は、駆動機構制御装置５により制御される。なお、センサ保持機構３および駆動機構４等の具体的構成については、後述する他の実施形態（図１１〜図１５等）において詳しく説明する。
【００２８】
駆動機構制御装置５は、装置全体の制御手段である入出力機構を有する制御装置６によって統括制御される。また、この制御装置６は、振動子Ａ（１）…Ａ（ｎ）を電子的に走査する手段、検査対象部位１の所定の位置に超音波ビームを集束および偏向する手段等を有している。
【００２９】
アレイ型超音波探触子２は、その任意の１個または複数の振動子を超音波送信用振動子および超音波受信用振動子として選択できる構成となっている。例えばこれら送受信用の振動子を群として選択する手段として、送信用各振動子に超音波を発生させる超音波送信器群８、受信用各振動子に超音波信号波形を受信させる超音波受信器群９等が備えられている。また、これらの超音波送信器群８と超音波受信器群９には遅延時間制御器７が接続され、これにより各振動子を制御することで、検査対象部位１の所定の位置に超音波ビームを集束および偏向させることができる。
【００３０】
さらに、超音波受信器群９には信号処理装置１０が接続されている。この信号処理装置１０は超音波送受信によって検出された超音波波形から欠陥信号を抽出し、アレイ型超音波探触子２の電子的走査位置あるいは機械的走査位置等に対する欠陥信号の振幅値分布を用いて欠陥位置、大きさ等を算出する手段である。信号処理装置１０には表示装置１１が接続され、制御装置６からの指令により、この信号処理された欠陥１ｂの位置および寸法等が画像出力および記録出力できるようになっている。
【００３１】
図２は、上述した超音波送信用振動子および超音波受信用振動子の種別等を示してある。すなわち、設定した送信用振動子群Ｇ（ｐ１），Ｇ（ｐ２），…，Ｇ（ｐｉ），…および受信用振動子群Ｇ（ｒ１），Ｇ（ｒ２），…，Ｇ（ｒｉ），…は、所定の電子走査により被検査対象部位を探傷することができる。
【００３２】
さらに、これらアレイ型超音波探触子２は、その任意の１個または複数の振動子を超音波送信用振動子群Ｇ（ｐ１），Ｇ（ｐ２），…，Ｇ（ｐｉ），…および受信用振動子群Ｇ（ｒ１），Ｇ（ｒ２），…，Ｇ（ｒｉ），…としてそれぞれ選択でき、送信用各振動子に超音波を発生させる超音波送信器群８が、また受信用各振動子には超音波信号波形を受信させる超音波受信器群９がそれぞれ繋がっている。そして、遅延時間制御器７により各振動子を制御することで、検査対象部位の所定の位置に超音波ビームを集束および偏向することができる。また、設定した送信用振動子群Ｇ（ｐ１），Ｇ（ｐ２），…，Ｇ（ｐｉ），…および受信用振動子群Ｇ（ｒ１），Ｇ（ｒ２），…，Ｇ（ｒｉ），…は、所定の電子走査により被検体を探傷することができる。さらに、これら電子走査により得られた超音波受信信号を信号処理器１０にて信号処理し、欠陥の有無、欠陥の位置、寸法などを表示装置１１にて画像出力および記録出力することができる。
【００３３】
図３〜図６は上記装置を使用して実施する超音波探傷方法を説明するための図である。図３は、アレイ型超音波探触子２を用いてＴＯＦＤ法を実施するための説明図である。
【００３４】
図３に示すように、本実施形態では被検査対象部位１の探傷において、所定の探傷屈折角θで探傷が可能となるようにアレイ型超音波探触子２内の所定の振動子Ａ（１），Ａ（２），…，Ａ（ｉ）を送信用振動子群Ｇ（ｐ１）として選定し、また他の振動子Ａ（ｊ），…，Ａ（ｎ）を受信用振動子群Ｇ（ｒ１）として選定する。
【００３５】
各振動子群の振動子は、振動子配列方向に電子的に１個ずつシフトさせながら探傷用の走査を制御装置６の制御によって行う。すなわち、送信振動子群Ｇ（ｐｉ）から送信された超音波ＵＴｂは、被検査対象部位１において、表面を伝播する表面波として、また内部に存在する欠陥１ｂの先端からの回折波として、さらに被検査対象部位１の底面からの反射波として、受信振動子群Ｇ（ｒｉ）により検出される。
【００３６】
この操作を電子走査にて行ったときに得られる出力画像例を図４に示す。すなわち図４（Ａ）に示すように、被検査対象部位１の底面にスリット等の欠陥１ｂが存在する場合、被検査対象部位１の表面では超音波が平行に進行し、欠陥１ｂの上端部位では回折波が発生する。また、底面では超音波が平行に進行する。この結果、図４（Ｂ）に示すように、被検査対象部位１の表面、底面およびその間に欠陥画像が明瞭に検出され、欠陥位置および欠陥寸法ｄを測定することができる。これらの結果は、電子走査にて行ったものであり、機械走査を伴わないため高精度測定が可能となる。
【００３７】
図５（Ａ）、（Ｂ）、（Ｃ）は、被検査対象部位１が極めて厚い板状構造物である場合についての説明図である。
【００３８】
前述した図３および図４に示す方法においては、超音波ビームの交点近傍の探傷は可能であるが、超音波ビームの交点から遠い位置、すなわち被検査対象部位１の表面近傍あるいは底面近傍では超音波反射波が弱く、適正な感度で探傷することができない。
【００３９】
そこで、図５（Ａ）に示すように、探傷屈折角を一定に設定した条件で、超音波ビームの交点が板厚の底面から表面まで連続的になるように、１組の超音波送信振動子群Ｇ（ｐ１）…と超音波受信振動子群Ｇ（ｒ１）…とを選定する。すなわち、被検査対象部位１の底面近傍に超音波ビームの交点を結ぶ場合（図５（Ａ）時間Ｔ１の場合）には、超音波送信振動子群と超音波受信振動子群とは、それぞれＧ（ｐ１）とＧ（ｒ１）、Ｇ（ｐ２）とＧ（ｒ２）のようにペアとして電子走査を行う。
【００４０】
次に、被検査対象部位１の中央近傍に超音波ビームの交点を結ぶ場合（図５（Ｂ）時間Ｔｉの場合）には、超音波送信振動子群と超音波受信振動子群をＧ（ｐ１）とＧ（ｒｉ）、Ｇ（ｐ２）とＧ（ｒｊ）のようにペアとして前記同様に、電子的走査を行う。これらの操作を板厚の底面から表面まで（図５（Ｃ））、連続的に行うことにより、検査対象部位１の全体に亘って探傷を行うことができ、高精度の欠陥検出、寸法測定が可能となる。さらに、前記走査を行った後に、欠陥信号が得られた位置に対して超音波を集束させて電子的に走査することで、より欠陥信号を高感度で検出することができ、高精度の探傷を行うことが可能となる。
【００４１】
図６は、前記探傷を行うための検査対象部位１に対するアレイ型超音波探触子２の設置位置の設定に関する説明図である。
【００４２】
アレイ型超音波探触子２の設置位置は、被検査対象部位１の板厚ｔ、その横波音速Ｖｓおよび縦波音速Ｖ_Ｌ、水浸法として水に代表される接触媒質Ｃの音速Ｖｗ、水から被検査対象部位１への入射角γ、探傷屈折角θとすると、被検体１とアレイ型超音波探触子の距離Ｗは、縦波および横波モードで探傷する場合、それぞれ下記の（１）式および（２）式を用いて設置することにより、適正な探傷を行うことができる。
【００４３】
【数１】
Ｗ＞（Ｖｗ／Ｖ_Ｌ）×ｔ ……（１）
【数２】
Ｗ＞（Ｖｗ／Ｖｓ）×ｔ ……（２）
また、送信および受信振動子群間の距離Ｌは、検査対象部位１が通常の板厚の場合、超音波ビームの交点が板厚の１／２ないしは２／３程度の範囲であれば適正な探傷が得られることを実験で確認しており、下記の（３）式の範囲を設定することにより、適正な探傷を行うことができる。
【００４４】
【数３】

【００４５】
第２実施形態（図７、図８）
図７および図８は本発明の第２実施形態による超音波探傷方法を説明するための図である。本実施形態は、アレイ型超音波探触子２の振動子Ａ（１）…Ａ（ｎ）を超音波送信用振動子および超音波受信用振動子として選定して電子的走査を行う前に、アレイ型超音波探触子の中から選択した１組の振動子群Ｇ（ｉ）…を送受信用として使用して被検査対象部位１の底部に向けて超音波ビームＵＴｂｃを扇形状に集束または偏向する電子的走査を行うことにより、予め欠陥位置情報を得るものである。
【００４６】
図７（Ａ），（Ｂ）は、この欠陥位置情報を得るために超音波ビームＵＴｂｃを扇形状に集束または偏向する様子を示したものである。
【００４７】
すなわち、これらの図に示すように、アレイ型超音波探触子２の中から１組の振動子群Ｇ（ｉ）を選択する。そして、これらの振動子群Ｇ（ｉ）を用いて下向きに、かつ溶接部１ａの方向に向けて超音波ビームＵＴｂを扇形状に集束・偏向させる電子走査を行いつつ、アレイ型超音波探触子２の配列方向に電子走査する手段を用いて扇形状に集束・偏向する探傷を行うものである。また、前記と反対側からも振動子群Ｇ（ｋ）を用いて溶接部１ａの方向に超音波ビームＵＴｂｃを扇形状に集束・偏向させる電子走査を行いつつ、アレイ型超音波探触子２の配列方向に電子走査する手段を用いて前記同様に扇形状に集束・偏向する探傷を行う。これらの探傷において、欠陥からの反射波の振幅値が最大となる屈折角θを求める。
【００４８】
このようにして求めた屈折角θを最適探傷条件として設定し、図８（Ａ），（Ｂ）に示すように、振動子群Ｇ（ｉ），Ｇ（ｊ），…を用いて溶接部１ａに対して両側から超音波ビームを集束させて入射させる。これらの操作をアレイ型超音波探触子２の全体を使用して電子走査による探傷を行うことにより、溶接部１ａに対して両側からの探傷をアレイ型超音波探触子２を機械走査する必要なく、探傷することができる。これらの探傷によって検出された欠陥信号を用いて、欠陥の位置、寸法を測定することができる。
【００４９】
第３実施形態（図９）
図９は、本発明の第３実施形態による超音波探傷方法を説明するための図である。本実施形態は溶接部１ａの形状が複雑な場合に好適なものであり、アレイ型超音波探触子２の振動子Ａ（１）…を超音波送信用振動子および超音波受信用振動子として選定して電子的走査を行う前に、アレイ型超音波探触子２の中から選択した１組の振動子群Ｇ（ｉ）を送受信用として使用し、超音波ビームＵＴｂが被検査対象部位の底面に反射して欠陥１ｂに入射する１回反射法による電子的走査を行うことにより、予め欠陥位置情報を得るものである。
【００５０】
すなわち、図９に示すように、被検査対象部位１、特に溶接構造物のアレイ型超音波探触子２を設置する側の表面探傷において、溶接部１ａの形状が複雑で前記の手段では探傷が困難な場合、１組の振動子群Ｇ（ｉ）を超音波送受信用として適用する。この場合、超音波ビームＵＴｂが被検査対象部位１の底面に反射して、被検査対象部位１の表面の欠陥１ｂに入射するように、図１に示した制御器６および遅延時間制御器７等の手段により、遅延時間を設定する探傷を電子走査によって当該溶接部１ａの全体に対して行う。これにより、アレイ型超音波探触子２を機械走査する必要なく探傷を行うことができ、検出された欠陥信号を用いて、欠陥の位置、寸法を測定することができる。
【００５１】
第４実施形態（図１０）
図１０は、本発明の第４実施形態による超音波探傷方法を説明するための図である。本実施形態は、アレイ型超音波探触子２の振動子Ａ（１）…を２組の振動子群に分け、その１組の振動子群Ｇ（ｉ）は送信用として被検査部位の側方に配置されて斜角探傷を電子的走査により行うものとし、他の組の振動子群Ｇ（ｊ）は受信用として被検査対象部位１の欠陥１ｂの発生が想定される位置の真上近傍に設置されて欠陥１ｂの先端からの回折波を検出するものである
すなわち、図１０に示すように、本実施形態においては、溶接部１ａからずれた位置の超音波送信振動子群Ｇ（ｉ）を適用して、被検査対象部位１の溶接部１ａに超音波ビームＵＴｂが送信されるような斜角探傷を行う設定としており、電子走査により振動子配列方向の探傷が行えるように設定されている。
【００５２】
一方、受信振動子群Ｇ（ｊ）は、被検査対象部位１の溶接部１ａの上側近傍に配置された振動子を適用し、垂直方向の信号を受信するように電子的に制御することで、欠陥１ｂへの超音波入射による欠陥先端からの回折波を検出することが可能となり、回折波のビーム路程と底面反射波のビーム路程との差から欠陥寸法を想定することが可能となる。
【００５３】
本実施形態によれば、選択された受信振動子群Ｇ（ｊ）が、溶接部１ａ全体の探傷を行うことが可能であれば、固定状態での探傷を行うこともできる。また、送信用振動子群Ｇ（ｉ）および受信振動子群Ｇ（ｊ）を一定の間隔で保持した状態で電子走査による探傷を行うことができる。
【００５４】
第５実施形態（図１１）
図１１は本発明の第５実施形態による超音波探傷装置を示す説明図である。本実施形態は、被検査対象部位が配管１１０等の構造物の溶接部（例えば突合せ溶接部、エルボ溶接部等）で、その溶接線（例えば周方向Ｒ）に沿う方向に発生する欠陥１ｂ（ｃ）を探傷するものである。
【００５５】
すなわち図１１に示すように、本実施形態ではアレイ型超音波探触子２の各振動子の配列方向を溶接線方向に対して直角方向に設定する手段として、配管１１０内に挿入される回転可能な軸等からなる駆動機構４を備える。また、アレイ型超音波探触子２を配管１１０の内表面に対して平行に移動させる手段としてフレーム等のセンサ保持機構３を備え、このセンサ保持機構３が駆動機構４に例えば摺動可能に支持されている。さらに、超音波入射方向を配管１１０の表面に対して垂直方向に位置設定する手段として、駆動機構４にセンサ保持機構３を位置決め等できるばね機構４１（その他、ギア機構４２、エアシリンダ機構４３）等が備えられ、これによりアレイ型超音波探触子２を配管１１０の表面から一定距離Ｗに保持できるようになっている。
【００５６】
そして、この状態を保持しつつ図示しないモータ等の駆動手段によってアレイ型超音波探触子２を溶接線方向（周方向Ｒ）に回転移動させるとともに、図１に示した信号処理装置１０等により、得られた欠陥信号の振幅値分布に基づいて欠陥の位置および寸法が測定および出力される。
【００５７】
本実施形態によれば、アレイ型超音波探触子２と配管１１０の探傷内面との距離がバネ機構４１、ギア機構４２あるいはエアシリンダ機構４３等によって設定保持され、一定の距離Ｗが保持された状態において、図１１に示すように配管１１０の円周方向に沿う溶接線方向の欠陥（周方向欠陥）１ｂ（ｃ）に対し、溶接線に直角方向に設置したアレイ型超音波探触子２により、溶接線に直角方向の探傷について前記電子走査による探傷を行いつつ、円周方向Ｒに沿う回転を行わせることによって、溶接部全体に対して適正な探傷を行うことができる。
【００５８】
第６実施形態（図１２）
図１２は本発明の第６実施形態による超音波探傷装置を示す説明図である。
【００５９】
本実施形態は第５実施形態の変形例であり、図１２に示すように、アレイ型超音波探触子２を配管１１０の探傷内面から一定距離Ｗだけ離間設定する手段を、アレイ型超音波探触子２あるいはセンサ保持機構３に取付けられ配管１１０の内表面に接触し得る伸縮可能な脚状の設定用治具４５によって構成したものである。
【００６０】
なお、本実施形態においても、電子走査による探傷を行いつつ、円周方向Ｒに沿う回転を行わせることによって、溶接部全体に対して適正な探傷を行うことができる。
【００６１】
第７実施形態（図１３）
図１３は本発明の第７実施形態による超音波探傷装置を示す説明図である。
【００６２】
本実施形態は、被検査対象部位が構造物の溶接部で、その溶接線に対して垂直方向に発生する欠陥１ｂ（ｃ）を探傷するものであり、アレイ型超音波探触子２を被検査対象部位の表面に対して例えば水平移動させる手段を備えたものである。
【００６３】
すなわち、図１３に示すように、配管１１０の外表面部分に軸方向沿うに欠陥１ｂ（ｃ）がある場合、アレイ型超音波探触子２を保持するセンサ保持機構３が水平なスライド機構３１を介して駆動機構４に水平方向にスライド可能に支持されている。
【００６４】
本実施形態によれば、アレイ型超音波探触子２を所定の位置に平行移動し、この状態欠陥１ｂ（ｃ）の斜め上方から超音波送受信を電子走査により行って探傷することで、欠陥面に超音波が入射され、欠陥反射波を検出することができる。
【００６５】
なお、本実施形態においても、電子走査による探傷を行いつつ、円周方向Ｒに沿う回転を行わせることによって、溶接部全体に対して適正な探傷を行うことができる。
【００６６】
第８実施形態（図１４）
図１４（Ａ），（Ｂ）は本発明の第８実施形態による超音波探傷装置を示す説明図である。
【００６７】
本実施形態も、配管１１０の溶接部１ａの溶接線に対して垂直方向に発生する欠陥１ｂを探傷するものであるが、図１３（Ａ），（Ｂ）に示すように、アレイ型超音波探触子２を配管１１０の内表面に接触し得る脚状の支持部材４６を有し、この支持部材４６によってアレイ型超音波探触子２を配管１１０の一側方に配置させ、また被検査対象部位の表面に対して傾斜させることが可能な構成となっている。なお、図示を省略しているが、アレイ型超音波探触子２は図１１に示した駆動機構４と同様の駆動機構で配管１１０内に支持してもよい。
【００６８】
このような構成によっても、アレイ型超音波探触子２を所定の位置に平行移動し、この状態で欠陥１ｂ（ｃ）の斜め上方から超音波送受信を電子走査により行って探傷することで、欠陥面に超音波が入射され、欠陥反射波を検出することができる。
【００６９】
本実施形態においても、電子走査による探傷を行いつつ、円周方向Ｒに沿う回転を行わせることによって、溶接部全体に対して適正な探傷を行うことができる。
【００７０】
第９実施形態（図１５）
図１５は本発明の第９実施形態による超音波探傷装置を示す説明図である。
【００７１】
本実施形態は、配管１１０の外周面側に溶接部の溶接線と垂直な方向に発生する欠陥１ｂ（ａ）を探傷するものである。
【００７２】
すなわち図１５に示すように、アレイ型超音波探触子２を保持するセンサ保持機構３に傾斜機構４７を設けることにより、アレイ型超音波探触子２に所定の傾斜角αを保持させることができるようになっている。なお、アレイ型超音波探触子２および傾斜機構４７は、センサ保持機構３および駆動機構４によって配管１１０内に支持されている。
【００７３】
本実施形態においても、アレイ型超音波探触子２に所定の傾斜を与え、この状態で欠陥１ｂ（ａ）の斜め上方から超音波送受信を電子走査により行って探傷することで、欠陥面に超音波が入射され、欠陥反射波を検出することにより配管外表面の軸方向に存在する欠陥の探傷を行うことができる。
【００７４】
本実施形態においても、電子走査による探傷を行いつつ、円周方向Ｒに沿う回転を行わせることによって、溶接部全体に対して適正な探傷を行うことができる。
【００７５】
第１０実施形態（図１６）
図１６（Ａ），（Ｂ）は本発明の第１０実施形態を示す説明図である。
【００７６】
本実施形態は、上述の図１１〜図１５に示した実施形態において、アレイ型超音波探触子２を円周方向Ｒに回転させて溶接部全体に対する探傷結果により、図１６（Ａ）に示すように、エコー高さと欠陥深さとの関係を求め、欠陥信号振幅値分布を得たものである。この図１６（Ａ）に示した各位置のピークｈ１，ｈ２，ｈ３等に基づいて図１６（Ｂ）に示すマスターカーブを作成することができる。このマスターカーブを各種配管等に対応して求めておくことにより、そのマスターカーブに基づき、未定の欠陥についても、エコー高さｈａから欠陥深さｄａ等の検出が行え、寸法測定が可能となる。
【００７７】
【発明の効果】
以上で詳述したように、本発明によれば、被検査対象部位の溶接部の探傷、特に水浸法による探傷等を行う場合、被検体がシーニング加工や曲面形状、薄板、極厚板など種々の状態であっても、対象部位の材質、形状、寸法から適正な探傷条件を求め、この探傷条件をもとにアレイ型超音波探傷装置を用いて探傷することにより、従来のＴＯＦＤ法や１回反射法、ペア構成のアレイ型超音波探触子などによる探傷と異なり、機械走査が不要な電子走査により、被検査対象部位の全体の欠陥検出、寸法測定を高速、かつ高精度で行うことができる。
【図面の簡単な説明】
【図１】本発明の第１実施形態による超音波探傷装置の機能ブロック図。
【図２】図１に示したアレイ型超音波探触子の拡大縦断面図。
【図３】図１に示した第１実施形態の作用を示す説明図。
【図４】（Ａ），（Ｂ）は図１に示した第１実施形態の作用および出力画像の例を示す図。
【図５】（Ａ），（Ｂ）、（Ｃ）は図１に示した第１実施形態における被検査対象部位が厚肉構造である場合の説明図。
【図６】図１に示した第１実施形態における探触子位置設定についての説明図。
【図７】（Ａ），（Ｂ）は本発明の第２の実施形態を示す説明図。
【図８】（Ａ），（Ｂ）は本発明の第３の実施形態に係る超音波探傷装置の電子走査に関する説明図。
【図９】図８に示した本発明の第３実施形態による超音波探傷方法を示す説明図。
【図１０】本発明の第４実施形態による超音波探傷方法を示す説明図。
【図１１】本発明の第５実施形態による超音波探傷装置を示す説明図。
【図１２】本発明の第６実施形態による超音波探傷装置を示す説明図。
【図１３】本発明の第７実施形態による超音波探傷装置を示す説明図。
【図１４】（Ａ），（Ｂ）は本発明の第８実施形態による超音波探傷装置を示す説明図。
【図１５】本発明の第９実施形態による超音波探傷装置を示す説明図。
【図１６】（Ａ），（Ｂ）は本発明の第１０実施形態を示す説明図。
【符号の説明】
１被検査対象部位
１ａ溶接部
１ｂ欠陥
２アレイ型超音波探触子
３センサ保持機構
４駆動機構
５駆動機構制御装置
６制御装置
７遅延時間制御器
８超音波送信器群
９超音波受信器群
１０信号処理装置
１１表示装置
３１スライド機構
４１バネ機構
４２ギア機構
４３エアシリンダ機構
４５設定用治具
４６支持部材
４７傾斜機構
１１０配管[0001]
BACKGROUND OF THE INVENTION
  The present invention is applied to defect inspection and the like by a water immersion method for welded structures and the like.Ultrasonic flaw detectorIn particular, high-speed and high-precision measurement of the presence or absence of overall defects and their dimensions for parts to be inspected, such as special shapes such as thin plates, extra-thick plates, curved surfaces, and complex welded parts. can doUltrasonic flaw detectorIt is about.
[0002]
[Prior art]
As a defect inspection method for various metal materials by an ultrasonic flaw detection method, an ultrasonic pulse reflection method in which ultrasonic waves are transmitted and received using one ultrasonic probe is widely used. This method is a method of detecting a reflected wave from a defect and measuring the position and size of the defect. For example, it is described in a nondestructive inspection manual (edited by the Japan Nondestructive Inspection Association, published by Nikkan Kogyo Shimbun). Yes.
[0003]
In addition, two probes are arranged opposite to each other with the welded portion interposed therebetween at right angles to the weld line direction of the welded portion that is the inspection target part, and the two probes are simultaneously machined perpendicularly to the weld line. A scanning method has also been proposed. This method is a method for measuring the position and size of a defect from information such as a diffracted wave from a defect tip and a bottom reflected wave. They are generally called the TOFD method (Time of Flight Diffraction Technique) and are described in the British Standard (BS) standard (1992).
[0004]
On the other hand, a defect inspection method using an array type ultrasonic probe in which a plurality of transducers are arranged has also been proposed (for example, “Ultrasonic Flaw Test III”: Japan Nondestructive Inspection Association, 1989). This method is a method of performing defect detection, dimension measurement, and the like by performing ultrasonic transmission / reception of an array type ultrasonic probe directly to an object to be inspected or via an acrylic wedge. With respect to this array-type ultrasonic flaw detector, for example, according to Japanese Patent Laid-Open Nos. 9-257773 and 9-257774, electronic scanning is performed so that each transducer sequentially transmits and receives ultrasonic waves according to a time difference. The technology to be used is disclosed.
[0005]
[Problems to be solved by the invention]
However, in the case where the ultrasonic pulse reflection method for transmitting and receiving ultrasonic waves using the single ultrasonic probe described above is performed by the water immersion method, the probe is used for defects that occur parallel to the weld line. Must be installed in a direction perpendicular to the weld line, and flaw detection by mechanical scanning must be performed in that direction, which may cause misalignment during movement of the mechanical scanning and the distance from the subject to be constant. There is a problem that defect information cannot be collected correctly, which is not preferable in terms of device health evaluation.
[0006]
Further, in the above-described TOFD method generally used for defect dimension measurement, two probes are arranged opposite to each other with a weld line interposed therebetween, and the two probes are simultaneously perpendicular to the weld line. Since the defect information is collected by performing mechanical scanning, and the dimensions are measured, the probe is exchanged for a probe with a different transducer angle, etc., every time the plate thickness and shape of the subject are different, and the optimum condition is determined to detect flaws. Need arises. Further, as in the case of the pulse reflection method, there is a possibility that a movement error due to the mechanical scanning of the probe may occur, which is not preferable in terms of evaluating the soundness of the device. Also, in the inspection of the part where the seam processing is applied to the welded part, the propagation time of the surface wave that becomes the reference in the dimension measurement of the defect by the TOFD method changes depending on the shape. May occur.
[0007]
Furthermore, in the defect inspection method using the conventional array-type ultrasonic probe, although electronic scanning is performed, each transducer sequentially transmits and receives ultrasonic waves individually. There are certain limitations on accuracy.
[0008]
The present invention has been made in view of such circumstances, and one or a plurality of transducers of an array-type ultrasonic probe are used for ultrasonic transmission according to the shape, thickness, etc. of a region to be inspected. The transducer and the receiving transducer are each appropriately selected as a set of transducers, and the optimal flaw detection refraction angle can be obtained while arbitrarily setting the flaw detection refraction angle by electronic scanning. It is possible to optimize various flaw detection conditions, such as the arrangement of probe groups and receiving probe groups, electronic scanning methods, etc., and to detect a subject under these optimum conditions. Ultrasonic flaw detection method and ultrasonic flaw detection capable of appropriately collecting the presence / absence of defects, dimensions, etc. regardless of the shape and size of the inspection target part The purpose is to provide equipment .
[0009]
[Means for Solving the Problems]
  In order to achieve the above object, according to the first aspect of the present invention, a plurality of vibrators are arranged.Means for installing an array-type ultrasonic probe on the surface of a region to be inspected, which can select any one or a plurality of transducers as an ultrasonic transmission transducer and an ultrasonic reception transducer; and the array type A means for selecting one or a plurality of transducers of the ultrasound probe as an ultrasound transmitting transducer and an ultrasound receiving transducer, and using the selected transducer group, a predetermined position of the site to be inspected is set. Means for focusing or deflecting the ultrasonic beam, means for performing electronic scanning of the ultrasonic transmission transducer and ultrasonic reception transducer, and a defect based on the ultrasonic waveform detected by the electronic scanning A means for extracting a signal and calculating a defect position and size using an amplitude value distribution of the defect signal with respect to an electronic scanning position of the array-type ultrasonic probe; and a means for outputting the measurement result. Special Ultrasonic flaw detection apparatus according toI will provide a.
[0014]
  In the invention of claim 1, a plurality of vibrators are arranged.Any one or a plurality of transducers can be selected as an ultrasound transmitting transducer and an ultrasound receiving transducer.Means for installing an array-type ultrasonic probe on the surface of a region to be inspected, and one or a plurality of transducers of the array-type ultrasonic probe as an ultrasonic transmission transducer and an ultrasonic reception transducer Means for selecting, means for converging or deflecting an ultrasonic beam at a predetermined position of a region to be inspected using the selected group of transducers, and electrons of the ultrasonic transmitting transducer and the ultrasonic receiving transducer A defect signal is extracted on the basis of the ultrasonic wave detected by the electronic scanning, and the amplitude value distribution of the defect signal with respect to the electronic scanning position of the array-type ultrasonic probe is used. There is provided an ultrasonic flaw detector provided with means for calculating the defect position and size and means for outputting the measurement result.
[0015]
  ClaimItem 2The invention claimsItem 1In the described ultrasonic flaw detector, the vibration for ultrasonic transmission based on the distance between the array-type ultrasonic probe and the site to be inspected, the sound velocity of the contact medium, the plate thickness and sound velocity of the site to be inspected, and the flaw refraction angle There is provided means for setting an interval between the probe and the probe for ultrasonic reception, and performing electronic scanning in a state where the number of the ultrasonic transmission transducer and the ultrasonic reception transducer is kept constant. An acoustic flaw detector characterized by the above is provided.
[0016]
  ClaimItem 3

The invention claimsItem

1 or 2In the described ultrasonic flaw detection apparatus, the ultrasonic refraction angle of the ultrasonic transmission transducer and the ultrasonic reception transducer are the same, and the intersection of the ultrasonic main beams is continuously extended from the bottom surface to the surface of the site to be inspected. There is provided an ultrasonic flaw detector characterized in that it is provided with a means for moving it.
[0017]
ClaimItem 4

The invention claimsItem

1 to 3In the ultrasonic flaw detector described in any of the above, the installation position of the array-type ultrasonic probe with respect to the inspected site is defined as a distance between the array-type ultrasonic probe and the inspected site. Characterized in that it comprises means for setting based on the sound velocity of water or other contact medium covering the region to be inspected, the thickness of the region to be inspected and its sound velocity, and the flaw detection refraction angle to the region to be inspected. An ultrasonic flaw detection apparatus is provided.
[0018]
ClaimItem 5

The invention claimsItem

1 to 4In the ultrasonic flaw detector described in any of the above, the inspection target part is a welded structure, and the transducer array direction of the array-type ultrasonic probe is set at a right angle to the weld line, and the weld line A means for online displaying an ultrasonic waveform data obtained at the time of ultrasonic transmission and reception while proceeding in a direction, and a means for measuring a defect position and a size with respect to the entire region to be inspected based on the image An ultrasonic flaw detector is provided.
[0019]
ClaimItem 6

The invention claimsItem

1 to 5In the ultrasonic flaw detector described in any of the above, the transducers of the array-type ultrasonic probe are divided into two sets of transducer groups, and the one set of transducers is a side of the region to be examined for transmission. The other group of transducers is installed near the position where the occurrence of a defect in the inspection target part is assumed for reception, and the tip of the defect is arranged. An ultrasonic flaw detector is provided that detects a diffracted wave from a laser beam.
[0020]
ClaimItem 7

The invention claimsItem

1 to 6In the ultrasonic flaw detector described in any of the above, the ultrasonic beam is fanned toward the bottom of the site to be inspected using a set of transducers selected from the array type ultrasonic probe. Obtained by means of electronic scanning for focusing or deflecting the shape, means for obtaining the refraction angle at which the amplitude value of the reflected wave from the defect becomes maximum, and electronic scanning while maintaining the refraction angle There is provided an ultrasonic flaw detector characterized by comprising means for obtaining the position and size of a defect from ultrasonic waveform information.
[0021]
ClaimItem 8

The invention claimsItem

1 to 7In the ultrasonic flaw detection apparatus according to any one of the above, a set of transducers for flaw detection on a surface on the probe side in a state where the array type ultrasonic probe is installed outside the inspection target site A single reflection method in which a group is applied for ultrasonic transmission / reception by electronic scanning, and an ultrasonic beam transmitted / received by the transducer group is reflected on the bottom surface of a material to be inspected and is incident on a surface defect of a region to be inspected. There is provided an ultrasonic flaw detector characterized by comprising means for enabling flaw detection.
[0022]
ClaimItem 9

The invention claimsItem

1 to 8In the ultrasonic flaw detector described in any of the above, the inspection target part is a welded portion of the structure, and a flaw that occurs in a direction along the weld line is flaw-detected. Means for setting the direction of arrangement of the transducers in a direction perpendicular to the welding line direction, means for moving the array-type ultrasonic probe parallel to the surface of the inspection object site, and ultrasonic waves Means for setting the incident direction in a direction perpendicular to the surface of the region to be inspected, and the amplitude of the defect signal obtained while moving the array-type ultrasonic probe in the weld line direction while maintaining this state There is provided an ultrasonic flaw detector characterized by comprising means for measuring the position and size of a defect based on a value distribution.
[0023]
ClaimItem 10

The invention claimsItem

1 to 9In the ultrasonic flaw detector described in any of the above, the inspection target part is a welded part of a structure, and a defect generated in a direction perpendicular to the weld line is flaw-detected. There is provided an ultrasonic flaw detector characterized by comprising means for inclining a child with respect to the surface of the inspection target site.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0025]
First embodiment (FIGS. 1 and 2)
FIG. 1 is a functional block diagram showing an embodiment of an ultrasonic flaw detector according to the present invention, and FIG. 2 is an enlarged longitudinal sectional view showing the array type ultrasonic probe shown in FIG.
[0026]
As shown in FIG. 1, this ultrasonic flaw detector uses a structure having a welded portion 1 a as an inspection target site 1 and inspects a defect 1 b existing in the vicinity of the welded portion 1 a of the inspection target site 1. Applicable. The array-type ultrasonic probe 2 has a plurality of transducers A (1)... A (n), which are arranged, for example, with water as a contact medium C and spaced apart from the inspection target site 1 by a certain distance. A (1)... A (n) is installed with the arrangement direction along the direction orthogonal to the weld line of the welded portion 1a.
[0027]
In the present embodiment, a sensor holding mechanism 3 is provided as means for installing the array-type ultrasonic probe 2 at an appropriate position, and the sensor holding mechanism 3 is driven by the drive mechanism 4 in the direction of the welding line or in a direction perpendicular thereto. Can be moved to. The movement amount, movement direction, and the like of the drive mechanism 4 are controlled by the drive mechanism control device 5. The specific configurations of the sensor holding mechanism 3 and the drive mechanism 4 will be described in detail in other embodiments (FIGS. 11 to 15 and the like) described later.
[0028]
The drive mechanism control device 5 is centrally controlled by a control device 6 having an input / output mechanism that is a control means of the entire device. Further, the control device 6 includes means for electronically scanning the transducers A (1)... A (n), means for focusing and deflecting the ultrasonic beam at a predetermined position of the inspection target site 1, and the like. Yes.
[0029]
The array-type ultrasonic probe 2 has a configuration in which any one or a plurality of transducers can be selected as an ultrasonic transmission transducer and an ultrasonic reception transducer. For example, as means for selecting these transducers for transmission / reception as a group, an ultrasonic transmitter group 8 that generates ultrasonic waves in each transducer for transmission, and an ultrasonic receiver that receives ultrasonic signal waveforms in each transducer for reception Group 9 etc. are provided. In addition, a delay time controller 7 is connected to the ultrasonic transmitter group 8 and the ultrasonic receiver group 9, thereby controlling each transducer, so that an ultrasonic wave is applied to a predetermined position of the examination target site 1. The beam can be focused and deflected.
[0030]
Further, a signal processing device 10 is connected to the ultrasonic receiver group 9. The signal processing apparatus 10 extracts a defect signal from an ultrasonic waveform detected by ultrasonic transmission / reception, and calculates an amplitude value distribution of the defect signal with respect to an electronic scanning position or a mechanical scanning position of the array-type ultrasonic probe 2. It is a means for calculating the defect position, size, etc. by using it. A display device 11 is connected to the signal processing device 10, and the position and dimensions of the signal-processed defect 1 b can be output and recorded by an instruction from the control device 6.
[0031]
FIG. 2 shows the types of the above-described ultrasonic transmission transducer and ultrasonic reception transducer. That is, the set transducer groups G (p1), G (p2),..., G (pi),... And the transducer groups G (r1), G (r2),. ... Can detect the inspection target site by predetermined electronic scanning.
[0032]
Furthermore, these array-type ultrasonic probes 2 are arranged with any one or a plurality of transducers as transducer groups G (p1), G (p2),..., G (pi),. An ultrasonic transmitter group 8 that can be selected as a receiving transducer group G (r1), G (r2),..., G (ri),. Each transducer is connected to an ultrasonic receiver group 9 for receiving an ultrasonic signal waveform. Then, by controlling each transducer by the delay time controller 7, the ultrasonic beam can be focused and deflected to a predetermined position of the examination target site. In addition, the set of transmitting transducer groups G (p1), G (p2),..., G (pi),... And the receiving transducer groups G (r1), G (r2),. ... can detect a subject by a predetermined electronic scanning. Further, the ultrasonic reception signals obtained by the electronic scanning can be signal-processed by the signal processor 10, and the display device 11 can output and record the image of the presence / absence of a defect, the position and size of the defect, and the like.
[0033]
3-6 is a figure for demonstrating the ultrasonic flaw detection method implemented using the said apparatus. FIG. 3 is an explanatory diagram for carrying out the TOFD method using the array-type ultrasonic probe 2.
[0034]
As shown in FIG. 3, in this embodiment, in the flaw detection of the site 1 to be inspected, a predetermined transducer A (in the array-type ultrasonic probe 2 (so that the flaw detection is possible at a predetermined flaw detection refraction angle θ). 1), A (2),..., A (i) are selected as the transmission transducer group G (p1), and the other transducers A (j),. Select as G (r1).
[0035]
The transducers in each transducer group perform scanning for flaw detection under the control of the control device 6 while electronically shifting the transducers one by one in the transducer array direction. That is, the ultrasonic wave UTb transmitted from the transmission transducer group G (pi) is further transmitted as a surface wave propagating on the surface in the inspection target site 1 and as a diffracted wave from the tip of the defect 1b existing inside. It is detected by the receiving transducer group G (ri) as a reflected wave from the bottom surface of the part 1 to be inspected.
[0036]
An example of an output image obtained when this operation is performed by electronic scanning is shown in FIG. That is, as shown in FIG. 4A, when a defect 1b such as a slit is present on the bottom surface of the inspection target region 1, ultrasonic waves travel in parallel on the surface of the inspection target region 1, and the upper end portion of the defect 1b. Then, a diffracted wave is generated. In addition, ultrasonic waves travel in parallel on the bottom surface. As a result, as shown in FIG. 4B, a defect image is clearly detected on the surface and bottom surface of the inspected site 1 and between them, and the defect position and the defect dimension d can be measured. These results were obtained by electronic scanning, and high-accuracy measurement is possible because no mechanical scanning is involved.
[0037]
FIGS. 5A, 5 </ b> B, and 5 </ b> C are explanatory diagrams when the inspection target site 1 is a very thick plate-like structure.
[0038]
In the method shown in FIG. 3 and FIG. 4 described above, flaw detection near the intersection of the ultrasonic beams is possible, but in the position far from the intersection of the ultrasonic beams, that is, near the surface or near the bottom surface of the part 1 to be inspected. The reflected sound wave is weak and cannot be detected with proper sensitivity.
[0039]
Therefore, as shown in FIG. 5A, a set of ultrasonic transmission vibrations so that the intersection of the ultrasonic beams is continuous from the bottom surface to the surface of the plate thickness under the condition that the flaw detection refraction angle is set constant. The child group G (p1)... And the ultrasonic receiving transducer group G (r1). That is, when an intersection of ultrasonic beams is connected near the bottom surface of the region 1 to be inspected (in the case of time T1 in FIG. 5A), the ultrasonic transmission transducer group and the ultrasonic reception transducer group are respectively Electronic scanning is performed as a pair such as G (p1) and G (r1) and G (p2) and G (r2).
[0040]
Next, when the intersection of the ultrasonic beams is connected near the center of the region 1 to be inspected (in the case of time Ti in FIG. 5B), the ultrasonic transmission transducer group and the ultrasonic reception transducer group are set to G ( Similarly to the above, electronic scanning is performed as a pair such as p1) and G (ri) and G (p2) and G (rj). By performing these operations continuously from the bottom surface to the surface of the plate thickness (FIG. 5C), it is possible to perform flaw detection over the entire inspection target region 1, and to detect defects with high accuracy and to measure dimensions. Is possible. Furthermore, after performing the scanning, the defect signal can be detected with higher sensitivity by focusing the ultrasonic wave on the position where the defect signal is obtained and scanning electronically, and highly accurate flaw detection. Can be performed.
[0041]
FIG. 6 is an explanatory diagram regarding the setting of the installation position of the array-type ultrasonic probe 2 with respect to the inspection target site 1 for performing the flaw detection.
[0042]
The installation position of the array-type ultrasonic probe 2 is the thickness t of the region 1 to be inspected, its transverse wave velocity Vs and longitudinal wave velocity V._LWhen the sound velocity Vw of the contact medium C typified by water as the water immersion method, the incident angle γ from the water to the inspection target site 1 and the flaw detection refraction angle θ, the distance between the subject 1 and the array-type ultrasonic probe W can perform proper flaw detection by using the following equations (1) and (2) when flaw detection is performed in the longitudinal wave mode and the transverse wave mode.
[0043]
[Expression 1]
W> (Vw / V_L) × t …… (1)
[Expression 2]
W> (Vw / Vs) × t (2)
The distance L between the transmitting and receiving transducer groups is appropriate when the inspection target region 1 has a normal plate thickness and the intersection of the ultrasonic beams is in the range of about 1/2 or 2/3 of the plate thickness. It has been confirmed by experiments that flaw detection is obtained, and proper flaw detection can be performed by setting the range of the following equation (3).
[0044]
[Equation 3]

[0045]
Second Embodiment (FIGS. 7 and 8)
7 and 8 are views for explaining an ultrasonic flaw detection method according to a second embodiment of the present invention. In this embodiment, the transducers A (1)... A (n) of the array-type ultrasonic probe 2 are selected as the ultrasonic transmission transducer and the ultrasonic reception transducer before electronic scanning. The ultrasonic beam UTbc is focused in a fan shape toward the bottom of the region 1 to be inspected by using a set of transducer groups G (i)... Selected from the array type ultrasonic probe for transmission / reception. Alternatively, defect position information is obtained in advance by performing electronic scanning for deflection.
[0046]
FIGS. 7A and 7B show how the ultrasonic beam UTbc is focused or deflected into a fan shape in order to obtain this defect position information.
[0047]
That is, as shown in these drawings, one set of transducer groups G (i) is selected from the array-type ultrasonic probe 2. The array type ultrasonic probe is used while performing electronic scanning to focus and deflect the ultrasonic beam UTb in a fan shape downward using the transducer group G (i) toward the welded portion 1a. A flaw detection for focusing and deflecting in a fan shape is performed using means for electronic scanning in the direction in which the elements 2 are arranged. Further, the array type ultrasonic probe 2 is also used from the side opposite to the above while performing electronic scanning to focus and deflect the ultrasonic beam UTbc in a fan shape in the direction of the welded portion 1a using the transducer group G (k). Using the means for electronic scanning in the array direction, flaw detection that converges and deflects in a fan shape is performed as described above. In these flaw detections, the refraction angle θ at which the amplitude value of the reflected wave from the defect is maximized is obtained.
[0048]
The refraction angle θ thus determined is set as an optimum flaw detection condition, and as shown in FIGS. 8A and 8B, a welded portion is used by using the vibrator group G (i), G (j),. An ultrasonic beam is focused from both sides and incident on 1a. These operations are performed by electronic scanning using the entire array-type ultrasonic probe 2, and the array-type ultrasonic probe 2 is mechanically scanned for flaw detection from both sides of the welded portion 1 a. Can be flawed without need. Using the defect signal detected by these flaw detections, the position and size of the defect can be measured.
[0049]
Third Embodiment (FIG. 9)
FIG. 9 is a diagram for explaining an ultrasonic flaw detection method according to a third embodiment of the present invention. This embodiment is suitable when the shape of the welded portion 1a is complicated, and the transducer A (1)... Of the array-type ultrasonic probe 2 is used as an ultrasonic transmission transducer and an ultrasonic reception transducer. Before the electronic scanning is performed, the set of transducer groups G (i) selected from the array-type ultrasonic probe 2 is used for transmission and reception, and the ultrasonic beam UTb is to be inspected. The defect position information is obtained in advance by performing electronic scanning by the one-time reflection method that is reflected on the bottom surface of the part and is incident on the defect 1b.
[0050]
That is, as shown in FIG. 9, in surface flaw detection on the inspection object site 1, particularly on the side where the array type ultrasonic probe 2 of the welded structure is installed, the shape of the welded portion 1a is complicated and flaw detection is performed by the above means. Is difficult, one set of transducer groups G (i) is applied for ultrasonic transmission / reception. In this case, the controller 6 and the delay time controller 7 shown in FIG. 1 are configured so that the ultrasonic beam UTb is reflected on the bottom surface of the inspection target region 1 and is incident on the defect 1b on the surface of the inspection target region 1. By such means, flaw detection for setting a delay time is performed on the entire welded portion 1a by electronic scanning. As a result, flaw detection can be performed without the need to mechanically scan the array-type ultrasonic probe 2, and the position and size of the defect can be measured using the detected defect signal.
[0051]
Fourth Embodiment (FIG. 10)
FIG. 10 is a diagram for explaining an ultrasonic flaw detection method according to a fourth embodiment of the present invention. In this embodiment, the transducers A (1)... Of the array-type ultrasonic probe 2 are divided into two sets of transducer groups, and the set of transducer groups G (i) It is assumed that oblique flaw detection is performed by electronic scanning, and the other group of transducer groups G (j) is true for the position where the defect 1b of the inspection target site 1 is expected to occur for reception. It is installed near the top and detects a diffracted wave from the tip of the defect 1b.
That is, as shown in FIG. 10, in this embodiment, the ultrasonic transmission transducer group G (i) at a position shifted from the welded portion 1a is applied to apply ultrasonic waves to the welded portion 1a of the site 1 to be inspected. It is set to perform oblique angle flaw detection so that the beam UTb is transmitted, and is set so that flaw detection in the direction of transducer arrangement can be performed by electronic scanning.
[0052]
On the other hand, the receiving transducer group G (j) applies a transducer disposed near the upper side of the welded portion 1a of the inspection target site 1 and electronically controls it to receive a vertical signal. Thus, it becomes possible to detect a diffracted wave from the tip of the defect due to the incidence of ultrasonic waves on the defect 1b, and it is possible to assume the defect size from the difference between the beam path of the diffracted wave and the beam path of the bottom reflected wave.
[0053]
According to the present embodiment, if the selected receiving transducer group G (j) can perform the entire flaw detection of the welded portion 1a, the flaw detection can be performed in a fixed state. Further, flaw detection by electronic scanning can be performed in a state where the transmitting transducer group G (i) and the receiving transducer group G (j) are held at a constant interval.
[0054]
Fifth embodiment (FIG. 11)
FIG. 11 is an explanatory view showing an ultrasonic flaw detector according to a fifth embodiment of the present invention. In the present embodiment, the inspection target part is a welded part (for example, a butt welded part, an elbow welded part, etc.) of a structure such as the pipe 110, and the defect 1b (in the direction along the circumferential direction R) is generated. c) flaw detection.
[0055]
That is, as shown in FIG. 11, in this embodiment, the rotation inserted into the pipe 110 as means for setting the arrangement direction of the transducers of the array-type ultrasonic probe 2 in a direction perpendicular to the welding line direction. A drive mechanism 4 comprising a possible shaft or the like is provided. In addition, a sensor holding mechanism 3 such as a frame is provided as means for moving the array-type ultrasonic probe 2 parallel to the inner surface of the pipe 110, and the sensor holding mechanism 3 is slidable on the drive mechanism 4, for example. It is supported. Further, as a means for setting the ultrasonic incident direction in a direction perpendicular to the surface of the pipe 110, a spring mechanism 41 that can position the sensor holding mechanism 3 in the drive mechanism 4 (other gear mechanism 42 and air cylinder mechanism 43). Thus, the array-type ultrasonic probe 2 can be held at a constant distance W from the surface of the pipe 110.
[0056]
While maintaining this state, the array-type ultrasonic probe 2 is rotated and moved in the welding line direction (circumferential direction R) by a driving means such as a motor (not shown) and the signal processing apparatus 10 shown in FIG. Based on the amplitude value distribution of the obtained defect signal, the position and size of the defect are measured and output.
[0057]
According to the present embodiment, the distance between the array-type ultrasonic probe 2 and the flaw detection inner surface of the pipe 110 is set and held by the spring mechanism 41, the gear mechanism 42, the air cylinder mechanism 43, etc., and a constant distance W is held. In this state, as shown in FIG. 11, an array-type ultrasonic probe installed in a direction perpendicular to the weld line with respect to a defect (circumferential defect) 1b (c) in the weld line direction along the circumferential direction of the pipe 110. 2. By performing the rotation along the circumferential direction R while performing flaw detection by electronic scanning for flaw detection in the direction perpendicular to the weld line, proper flaw detection can be performed on the entire welded portion.
[0058]
Sixth embodiment (FIG. 12)
FIG. 12 is an explanatory view showing an ultrasonic flaw detector according to a sixth embodiment of the present invention.
[0059]
This embodiment is a modification of the fifth embodiment, and as shown in FIG. 12, means for setting the array-type ultrasonic probe 2 away from the flaw detection inner surface of the pipe 110 by a fixed distance W is an array-type ultrasonic. This is configured by an extendable leg-shaped setting jig 45 that is attached to the probe 2 or the sensor holding mechanism 3 and can contact the inner surface of the pipe 110.
[0060]
In the present embodiment as well, by performing rotation along the circumferential direction R while performing flaw detection by electronic scanning, proper flaw detection can be performed on the entire welded portion.
[0061]
Seventh embodiment (FIG. 13)
FIG. 13 is an explanatory view showing an ultrasonic flaw detector according to a seventh embodiment of the present invention.
[0062]
In the present embodiment, the inspection target site is a welded portion of a structure, and a defect 1b (c) generated in a direction perpendicular to the weld line is detected, and the array type ultrasonic probe 2 is covered. For example, a means for horizontally moving the surface of the inspection target part is provided.
[0063]
That is, as shown in FIG. 13, when there is a defect 1 b (c) along the axial direction on the outer surface portion of the pipe 110, the sensor holding mechanism 3 that holds the array type ultrasonic probe 2 is a horizontal slide mechanism 31. Is slidably supported by the drive mechanism 4 in the horizontal direction.
[0064]
According to the present embodiment, the array-type ultrasonic probe 2 is translated to a predetermined position, and ultrasonic transmission / reception is carried out by electronic scanning from obliquely above the state defect 1b (c) to detect the defect. Ultrasonic waves are incident on the surface, and defect reflected waves can be detected.
[0065]
In the present embodiment as well, by performing rotation along the circumferential direction R while performing flaw detection by electronic scanning, proper flaw detection can be performed on the entire welded portion.
[0066]
Eighth embodiment (FIG. 14)
14A and 14B are explanatory views showing an ultrasonic flaw detector according to the eighth embodiment of the present invention.
[0067]
In this embodiment, the defect 1b generated in the direction perpendicular to the weld line of the welded portion 1a of the pipe 110 is also detected. As shown in FIGS. 13 (A) and 13 (B), array type ultrasonic waves are used. The probe 2 has a leg-shaped support member 46 that can come into contact with the inner surface of the pipe 110, and the array-type ultrasonic probe 2 is arranged on one side of the pipe 110 by the support member 46. It is the structure which can be made to incline with respect to the surface of a test object site | part. Although not shown, the array-type ultrasonic probe 2 may be supported in the pipe 110 by a drive mechanism similar to the drive mechanism 4 shown in FIG.
[0068]
Even with such a configuration, the array-type ultrasonic probe 2 is translated to a predetermined position, and in this state, ultrasonic transmission / reception is performed by electronic scanning from obliquely above the defect 1b (c), and flaw detection is performed. An ultrasonic wave is incident on the defect surface, and a defect reflected wave can be detected.
[0069]
Also in the present embodiment, by performing rotation along the circumferential direction R while performing flaw detection by electronic scanning, proper flaw detection can be performed on the entire welded portion.
[0070]
Ninth embodiment (FIG. 15)
FIG. 15 is an explanatory view showing an ultrasonic flaw detector according to the ninth embodiment of the present invention.
[0071]
In the present embodiment, the defect 1b (a) occurring on the outer peripheral surface side of the pipe 110 in a direction perpendicular to the weld line of the welded portion is detected.
[0072]
That is, as shown in FIG. 15, by providing the tilting mechanism 47 in the sensor holding mechanism 3 that holds the array-type ultrasonic probe 2, the array-type ultrasonic probe 2 is held at a predetermined tilt angle α. Can be done. The array-type ultrasonic probe 2 and the tilt mechanism 47 are supported in the pipe 110 by the sensor holding mechanism 3 and the drive mechanism 4.
[0073]
Also in the present embodiment, the array-type ultrasonic probe 2 is given a predetermined inclination, and in this state, ultrasonic transmission / reception is performed by electronic scanning from obliquely above the defect 1b (a) to detect the defect surface. By detecting the reflected wave with the ultrasonic wave incident, it is possible to detect a defect present in the axial direction of the outer surface of the pipe.
[0074]
Also in the present embodiment, by performing rotation along the circumferential direction R while performing flaw detection by electronic scanning, proper flaw detection can be performed on the entire welded portion.
[0075]
Tenth embodiment (FIG. 16)
FIGS. 16A and 16B are explanatory views showing a tenth embodiment of the present invention.
[0076]
In this embodiment, in the embodiment shown in FIGS. 11 to 15, the array type ultrasonic probe 2 is rotated in the circumferential direction R, and the result of flaw detection on the entire welded portion is shown in FIG. As shown, the relationship between the echo height and the defect depth is obtained, and the defect signal amplitude value distribution is obtained. A master curve shown in FIG. 16B can be created based on the peaks h1, h2, h3, etc. at the respective positions shown in FIG. By obtaining this master curve corresponding to various pipes and the like, it is possible to detect the defect depth da and the like from the echo height ha based on the master curve, and to measure the dimension of the undetermined defect. .
[0077]
【The invention's effect】
As described above in detail, according to the present invention, when performing a flaw detection on a welded portion of a region to be inspected, particularly a flaw detection by a water immersion method, the object is subjected to a seaming process, a curved surface shape, a thin plate, a very thick plate, etc. Even in various states, an appropriate flaw detection condition is obtained from the material, shape, and dimensions of the target portion, and flaw detection is performed using an array-type ultrasonic flaw detector based on this flaw detection condition. Unlike flaw detection using a single-reflection method or a paired array type ultrasonic probe, etc., the entire defect detection and dimension measurement of the inspection target site are performed at high speed and with high accuracy by electronic scanning that does not require mechanical scanning. be able to.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of an ultrasonic flaw detector according to a first embodiment of the present invention.
2 is an enlarged longitudinal sectional view of the array-type ultrasonic probe shown in FIG. 1. FIG.
FIG. 3 is an explanatory diagram showing the operation of the first embodiment shown in FIG. 1;
FIGS. 4A and 4B are diagrams showing an example of an operation and an output image of the first embodiment shown in FIG.
FIGS. 5A, 5B, and 5C are explanatory views when a portion to be inspected has a thick structure in the first embodiment shown in FIG.
6 is an explanatory diagram of probe position setting in the first embodiment shown in FIG. 1; FIG.
FIGS. 7A and 7B are explanatory diagrams showing a second embodiment of the present invention. FIGS.
FIGS. 8A and 8B are explanatory diagrams relating to electronic scanning of an ultrasonic flaw detector according to a third embodiment of the present invention.
9 is an explanatory view showing an ultrasonic flaw detection method according to a third embodiment of the present invention shown in FIG.
FIG. 10 is an explanatory view showing an ultrasonic flaw detection method according to a fourth embodiment of the present invention.
FIG. 11 is an explanatory view showing an ultrasonic flaw detector according to a fifth embodiment of the present invention.
FIG. 12 is an explanatory view showing an ultrasonic flaw detector according to a sixth embodiment of the present invention.
FIG. 13 is an explanatory view showing an ultrasonic flaw detector according to a seventh embodiment of the present invention.
14A and 14B are explanatory views showing an ultrasonic flaw detector according to an eighth embodiment of the present invention.
FIG. 15 is an explanatory view showing an ultrasonic flaw detector according to a ninth embodiment of the present invention.
16A and 16B are explanatory views showing a tenth embodiment of the present invention.
[Explanation of symbols]
1 part to be examined
1a Welded part
1b Defect
2 Array type ultrasonic probe
3 Sensor holding mechanism
4 Drive mechanism
5 Drive mechanism controller
6 Control device
7 Delay time controller
8 Ultrasonic transmitters
9 Ultrasonic receivers
10 Signal processing device
11 Display device
31 Slide mechanism
41 Spring mechanism
42 Gear mechanism
43 Air cylinder mechanism
45 Setting jig
46 Support member
47 Tilting mechanism
110 Piping

Claims

An array type ultrasonic probe that can arrange multiple transducers and select any one or more transducers as an ultrasonic transmission transducer and an ultrasonic reception transducer is installed on the surface of the site to be inspected. Means for selecting one or more transducers of the array-type ultrasonic probe as an ultrasonic transmitting transducer and an ultrasonic receiving transducer, and using the selected transducer group Means for focusing or deflecting the ultrasonic beam at a predetermined position of the inspection target part, means for performing electronic scanning of the ultrasonic transmission transducer and the ultrasonic reception transducer, and detected by this electronic scanning A means for extracting a defect signal based on an ultrasonic waveform, calculating a defect position and a size using an amplitude value distribution of the defect signal with respect to an electronic scanning position of the array-type ultrasonic probe, and a result of the measurement. Hand to output Ultrasonic flaw detection apparatus characterized by comprising and.

2. The ultrasonic flaw detector according to claim 1, wherein the ultrasonic wave is detected based on the distance between the array-type ultrasonic probe and the site to be inspected, the sound velocity of the contact medium, the plate thickness and sound speed of the site to be inspected, and the flaw refraction angle. Means for setting an interval between the transmitting transducer and the ultrasonic receiving probe and performing electronic scanning in a state where the number of the ultrasonic transmitting transducer and the ultrasonic receiving transducer is kept constant. An acoustic flaw detector characterized by comprising:

3. The ultrasonic flaw detection apparatus according to claim 1, wherein the flaw detection refraction angles of the ultrasonic transmission transducer and the ultrasonic reception transducer are the same, and the intersection of the ultrasonic main beams is defined from the bottom surface of the inspection target site to the surface. An ultrasonic flaw detector characterized by comprising means for moving continuously over a distance.

The ultrasonic flaw detector according to any one of claims 1 to 3 , wherein an installation position of the array-type ultrasonic probe with respect to the inspection target site is defined by the array-type ultrasonic probe, the inspection target site, and the like. And a sound speed of water or other contact medium covering the inspection target part, a plate thickness of the inspection target part and its sound speed, and a flaw detection refraction angle to the inspection target inspection part. An ultrasonic flaw detector characterized by that.

The ultrasonic flaw detector according to any one of claims 1 to 4, wherein the inspection target part is a welded structure, and the transducer arrangement direction of the array-type ultrasonic probe is perpendicular to the weld line. Means for online display of ultrasonic waveform data obtained at the time of ultrasonic transmission / reception while setting and proceeding in the direction of the welding line, and measuring the defect position and size with respect to the entire region to be inspected based on the image And an ultrasonic flaw detector.

6. The ultrasonic flaw detector according to claim 1, wherein the transducer of the array-type ultrasonic probe is divided into two sets of transducer groups, and the one set of transducer groups is used for transmission. It is assumed that the oblique flaw detection is carried out by electronic scanning and is arranged on the side of the inspection site, and the other group of transducer groups is located immediately above the position where the occurrence of the defect in the inspection target region is assumed for reception. An ultrasonic flaw detector which is installed and detects a diffracted wave from a defect tip.

The ultrasonic flaw detector according to any one of claims 1 to 6 , wherein one set of transducers selected from an array type ultrasonic probe is used toward the bottom of the site to be inspected. A means for performing electronic scanning to focus or deflect the ultrasonic beam into a fan shape, a means for obtaining a refraction angle at which the amplitude value of the reflected wave from the defect is maximized, and an electronic device with the refraction angle maintained. An ultrasonic flaw detector comprising: means for obtaining the position and size of a defect from ultrasonic waveform information obtained by scanning.

In the ultrasonic flaw detection apparatus according to any one of claims 1 to 7 , in the case of flaw detection of a defect generated on the surface on the probe side in a state where the array type ultrasonic probe is installed outside the site to be inspected, A set of transducers is applied for ultrasonic transmission / reception by electronic scanning, and an ultrasonic beam transmitted / received by the transducers is reflected on the bottom surface of the material to be examined and is incident on a surface defect of a region to be inspected. An ultrasonic flaw detection apparatus comprising means for enabling flaw detection by a single reflection method.

The ultrasonic flaw detector according to any one of claims 1 to 8, wherein the inspection target part is a welded portion of a structure and flaws occurring in a direction along the weld line are detected. Means for setting the arrangement direction of the transducers of the acoustic probe in a direction perpendicular to the welding line direction, and moving the array-type ultrasonic probe in parallel with the surface of the inspection target site And means for setting the ultrasonic incident direction in a direction perpendicular to the surface of the inspected site, and moving the array-type ultrasonic probe in the welding line direction while maintaining this state. An ultrasonic flaw detector comprising: means for measuring a position and a dimension of a defect based on an amplitude value distribution of a defect signal to be obtained.

The ultrasonic flaw detector according to any one of claims 1 to 9, wherein the inspection object part is a welded portion of a structure, and a defect generated in a direction perpendicular to the weld line is flaw-detected. An ultrasonic flaw detector provided with means for inclining a type ultrasonic probe with respect to the surface of the inspection target site.