JP3874686B2

JP3874686B2 - Magnetic flaw detection method and magnetic flaw detection apparatus

Info

Publication number: JP3874686B2
Application number: JP2002086635A
Authority: JP
Inventors: 建郎安松; 祥司土肥; 秀樹早川; 誠竹中; 行央岸本
Original assignee: Osaka Gas Co Ltd
Current assignee: Osaka Gas Co Ltd
Priority date: 2002-03-26
Filing date: 2002-03-26
Publication date: 2007-01-31
Anticipated expiration: 2022-03-26
Also published as: JP2003279545A

Description

【０００１】
【発明の属する技術分野】
本発明は、磁束密度に対応したパターンを形成する感磁体を封入したシート状で柔軟な磁気探傷シートを被検査対象に接触させ、この接触状態において磁気発生機構で発生させた磁気を被検査対象に作用させることで被検査対象から漏洩する磁束を磁気探傷シートの感磁体で捉え、この感磁体が作り出すパターンに基づいて被検査対象の探傷を行う磁気探傷方法および磁気探傷装置に関する。
【０００２】
【従来の技術】
上記のように構成された磁気探傷方法と類似する技術として特開昭５６‐４０７５２号公報や特開２００１‐２１５３９号公報に示されるものが存在する。
【０００３】
これらの従来の技術のうち前者は、上面及び側面が透明で底部が非伝導性弾性薄膜で成る容器の内部に、水や灯油と磁粉との懸濁液を充満させて検査カセット（シート状でないが本発明の磁気探傷シートに対応する）を構成し、この検査カセットの底部（非伝導性弾性薄膜）を被検査対象に接触させた状態で、被検査対象に対して磁化装置（本発明の磁気発生機構）から磁力を作用させ、被検査構造物（本発明の被検査対象）から漏洩した磁束の状態をカセット内部の磁粉のパターンで捉え被検査構造物の欠陥部の状態を把握できるものにしている。又、検査カセットを被検査構造物に接触させる際には、下面の薄膜が被検査構造物の表面形状に沿うよう変形することにより、薄膜を被検査構造物の表面に密着するものとなっている。
【０００４】
従来の技術のうち後者は、２枚の透明シートの間に多数の小室を有し、夫々の小室に対して磁粉を分散させた白色分散媒を封入して磁気シート（本発明の磁気探傷シート）を構成している。この磁気シートでは、消磁磁石から磁力を作用させることで小室内の磁粉をシートの一方の面の側に一様に移動させておき、この後に磁力が作用させた場合に小室内で磁粉が移動したことを磁粉模様から観察できるよう構成している。又、この従来の技術では、バッチ式磁粉探傷装置として磁気シートを被探傷体（本発明の被検査対象）に接触させた状態で、この磁気シートに対して多数のスプリングからのばね力を作用させることで、磁気シートと被探傷体とを密接させ得るように構成されている。尚、この磁気シートは被探傷体に接触させた面にパターンが現れるので、探傷時には磁気シートを捲り上げる形態でパターンを確認する作業を必要とする。
【０００５】
【発明が解決しようとする課題】
従来の技術の前者（特開昭５６‐４０７５２号公報）に示される検査カセットと同様に容器内に磁粉を封入した磁気探傷シートを用いて検査（探傷）を行うことを考えると、この磁気探傷シートが磁気の作用を受けて機能するものであるので、水中での検査に限らず、地上において被検査対象（従来の技術の被検査構造物）の表面に対して磁気探傷シートを密接させて検査を行うことが検査精度を向上させる点で重要である。しかし、密着させるために作業者が手で押さえる等の形態の作業では、均一な密着を行えないばかりか、作業者の負担となる。
【０００６】
そこで、従来の技術の後者（特開２００１‐２１５３９号公報）に示されるバッチ式磁粉探傷装置に示される技術を用いることも考えられる。この技術では、多数のスプリングからの押圧力を磁気シート（本発明の磁気探傷シート）に作用させることで磁気シートを被探傷体（本発明の被検査対象）に密接させるので、作業者の負担とならず比較的に容易な作業を実現する反面、多数のスプリングを使用するので部品数が増大して探傷用の機器が複雑化しやすく、又、多数のスプリングを用いているので、スプリングからの付勢力が直接作用する部位の近傍で圧力が高く、その周囲では圧力が低くなることから、均一な圧接を行い難い面で改善の余地がある。特に、この検査が溶接箇所の欠陥を検出するために多く採用されることから、溶接箇所における余盛り部分のように表面の凹凸のレベル差が大きい被探傷体や、パイプ類のように大きく湾曲した被探傷体に対してはスプリングでは対応し難い面がある。
【０００７】
尚、探傷を行う場合に、磁気探傷シートの下面が被検査対象の検査面から浮き上がった場合には、その浮き上がり量（リフトオフ量）が０．１ｍｍ程度であっても、検査不能に陥ることも多く、このような観点からも良好な密着性能を現出する技術が望まれているのである。
【０００８】
本発明の目的は、被検査対象の表面に対して磁気探傷シートを密接させて磁気により検査を行える検査方法を合理的に構成する点にある。
【０００９】
【課題を解決するための手段】
本発明の請求項１に係る磁気探傷方法及び請求項６に係る磁気探傷装置の特徴、作用・効果は次の通りである。
〔特徴〕
本発明の磁気探傷方法の特徴は、磁束密度に対応したパターンを形成する感磁体を封入したシート状で柔軟な磁気探傷シートを被検査対象に接触させ、この接触状態において磁気発生機構で発生させた磁気を被検査対象に作用させることで被検査対象から漏洩する磁束を磁気探傷シートの感磁体で捉え、この感磁体が作り出すパターンに基づいて被検査対象の探傷を行う磁気探傷方法において、前記磁気探傷シートを被検査対象に接触させた状態で、この被検査対象の反被検査対象側面に対して、透明なゲル状物質で構成された柔軟に変形し得る押圧部材を配置し、この押圧部材に対して透明な板状の圧着板で構成された圧力付与機構から圧力を作用させることにより磁気探傷シートを被検査対象に押し付ける状態で被検査対象の探傷を行う点にある。
本発明の磁気探傷装置の特徴は、被検査対象に接触させるものであり、磁束密度に対応したパターンを形成する感磁体を封入した柔軟な磁気探傷シートと、磁極を前記被検査対象に接触させた状態で、磁気を前記被検査対象に作用させる磁気発生機構と、前記磁気探傷シートを前記被検査対象に接触させた状態で、前記被検査対象の反被検査対象側面に対して配置されるものであり、透明なゲル状物質で構成された柔軟に変形し得る押圧部材と、前記押圧部材に対して圧力を作用させることにより、前記磁気探傷シートを前記被検査対象に押し付ける透明な板状の圧着板で構成された圧力付与機構とを備えた点にある。
【００１０】
〔作用・効果〕
上記特徴によると、探傷を行う場合には、被検査対象の表面にシート状となる磁気探傷シートを接触させ、この磁気探傷シートの反被検査対象側面に対して押圧部材を接触させた状態で圧力付与機構から圧力を作用させるので、この押圧部材が変形することにより磁気探傷シートの反被検査対象側面に対して広い面を介して密接した状態で、この広い面に対して均一の圧力を作用させるものとなり、この均一な圧力により磁気探傷シートを被検査対象の表面に沿う形状となるよう密着させることが可能となる。その結果、柔軟に変形し得る押圧部材を介在させて磁気探傷シートに圧力を作用させる手段を採用するだけで、磁気探傷シートを被検査対象から浮き上がらせること無く、夫々を広い面で密接させて精度高く探傷を行いうる方法及び装置が合理的に構成された。
【００１２】
また、柔軟な樹脂フィルムで成る袋に対して、透明なゲル状物質で構成された柔軟に変形し得る材料自体で成る押圧部材は、柔軟に変形し得るものの良好に圧力伝える性能を具備したものとなり、圧力付与機構として圧着板を用いたものは大きく変形させること無く、押圧部材に対して圧力を作用させるものとなる。その結果、探傷を行う際には、被検査対象の上面に磁気探傷シートを載せ付け、この磁気探傷シートの上面に、押圧部材と圧着板とを載せ付けるだけで済み、極めて簡単な操作によって探傷を行えるものとなった。
【００１４】
さらに、ゲル状物質で構成された柔軟に変形し得る押圧部材と板状の圧着板で構成された圧力付与機構とが透明であるので、被検査対象の表面に接触させた磁気探傷シートの磁粉の状態を押圧部材と圧力付与機構とを透過する光線により視覚的に捉え得る。その結果、磁気探傷シートを捲り上げて被検査対象側の面を露出させる如き操作を行わずとも探傷が可能となる。
【００１５】
本発明の請求項２に係る磁気探傷方法の特徴、作用・効果は次の通りである。
〔特徴〕
請求項１に記載の磁気探傷方法において、前記磁気探傷シートが、柔軟な上面側のシート材と柔軟な下面側のシート材とを重ね合わせ、この間に、前記感磁体として分散媒に分散した磁粉を封入したシート状に成形されている点にある。
【００１６】
〔作用・効果〕
上記特徴によると、柔軟な上下のシート材に挟まれる部位に磁粉が存在するので、磁気探傷シートの全体を薄くして探傷時の感度を高くできると同時に、磁気探傷シートの全体を柔軟に変形させ得るものとなり、探傷を行う際には被検査対象に磁気探傷シートを接触させ、押圧部材と圧着板とを重ね合わせるだけで、被検査対象の表面に磁気探傷シートを密着させ、かつ、この被検査対象からの磁束を磁粉で高感度で捉えるものとなる。その結果、磁気探傷シートを取り扱いやすくしながら、能率高く探傷を行えるものとなった。
【００１７】
本発明の請求項３に係る磁気探傷方法の特徴、作用・効果は次の通りである。
〔特徴〕
請求項１に記載の磁気探傷方法において、前記磁気探傷シートが、柔軟な上面側のシート材と柔軟な下面側のシート材との間に多数のカプセル部を形成し、夫々のカプセル部に対して分散媒に分散した磁粉を封入して構成されている点にある。
【００１８】
〔作用・効果〕
上記特徴によると、磁気探傷シートが、多数のカプセル部に分散媒に分散した磁粉を封入して構成されるので、探傷を行った場合には、夫々のカプセル部における磁粉の移動で形成されるパターンに基づいて探傷を行い得る。つまり、従来の技術の後者と同様に、磁気が作用した場合にはカプセル部に封入した磁粉によってパターンを形成するので、磁気探傷シート全体における磁粉の偏りを無くしながら、比較的簡単にコントラストを高めた状態となるパターンを形成し得るのである。その結果、視覚的に把握しやすいパターンを形成して探傷を行えるものとなった。
【００１９】
本発明の請求項４に係る磁気探傷方法の特徴、作用・効果は次の通りである。
〔特徴〕
請求項２又は３に記載の磁気探傷方法において、前記上面側のシート材および前記下面側のシート材のうち、少なくとも１つが透明である点にある。
【００２０】
〔作用・効果〕
上記特徴によると、上面側のシート材、あるいは、下面側のシート材のうち透明であるものの側から磁気探傷シートにおける磁粉のパターン、あるいは、カプセル部に封入した磁粉のパターンを視覚的に把握できるばかりか、例えば、上面側と下面側とのシート材が透明である場合には、被検査対象の探傷面と磁気探傷シートとの位置決めを容易に行える。その結果、簡便な操作で確実な探傷を実現する。
【００２１】
本発明の請求項５に係る磁気探傷方法の特徴、作用・効果は次の通りである。
〔特徴〕
請求項１〜４のいずれか１項に記載の磁気探傷方法において、前記圧力付与機構が、バネ材あるいはゴム材の弾性力、磁力による吸着力を用いた点にある。
【００２２】
〔作用・効果〕
上記特徴によると、バネ材やゴム材からの弾性力、あるいは、磁力による吸着力を作用させるので、例えば、被検査対象の表面（検査面）が斜め姿勢や、垂直の姿勢であっても、被検査対象の表面に磁気探傷シートを密接させて探傷を行うことも可能となる。その結果、被検査対象の表面の姿勢に拘わらず良好に探傷を行えるものとなった。
【００２３】
【発明の実施の形態】
以下、本発明の実施の形態を図面に基づいて説明する。
〔第１実施の形態〕
図１及び図２に示すように、被検査対象１の表面に接触させる磁気探傷シートＳと、この磁気探傷シートＳを被検査対象１に圧着させる押圧手段Ｐと、被検査対象１に磁気を作用させる磁気発生機構Ｍとを備えて磁気探傷装置が構成されている。この磁気探傷装置は本発明の磁気探傷方法を実現するための代表的な構成であり、この磁気探傷方法では鉄を代表とする磁性体を被検査対象１とし、具体的には鉄板材の溶接箇所の余盛り部分１Ａや、鉄製の配管の曲面部分の欠陥Ｃ（クラック等の傷）の検査を行うためのものである。尚、この余盛り部分１Ａとして、幅１０ｍｍ程度で、被検査対象１から１ｍｍ程度の盛り上がり高さを有した一般的な形態のものを想定している。
【００２４】
前記磁気探傷シートＳは、図３に示すように、柔軟で透明な樹脂フィルムで成る上面側の表面材１０と、柔軟な樹脂フィルムで成る下面側の裏面材１１とを重ね合わせ、夫々の素材同士の間に複数のスペーサ１２を介在させることで２０〜３０μｍ程度の隙間ｄを形成した柔軟なシート状に成形した容器を使用し、この容器に対して磁性体で０．１μｍ程度以上で、前記隙間の値（２０〜３０μｍ程度）より充分に小さい粒径となる粒子状の磁粉１３（感磁体の一例）と、気体あるいは流動性を有する流動物質１４（分散媒の一例）とを封入して構成されている。又、磁気探傷シートＳの容器は、表面材１０と裏面材１１との外周部を熱溶着の技術や接着剤を用いて接合することで密封構造を有して成り、前記磁粉１３には蛍光物質がコーティングしたものを用いても良い。
【００２５】
具体的に説明すると、表面材１０と裏面材１１とのフィルム厚が０．０２〜０．５ｍｍ程度のものが使用されており、容器の表面材１０は透明であることが必須であるが、多少の着色したものを使用しても良く、裏面材１１は透明である必要は無く、着色した樹脂を用いることも可能である。この表面材１０と裏面材１１としてポリエチレンやポリビニルやＰＥＴ（polyethylene terephthalate）樹脂の使用が可能であり、又、裏面材１１として樹脂フィルムに代えて軟磁性のオーステイトステンレス鋼の箔を使用することも可能である。
【００２６】
前記スペーサ１２は、２０〜３０μｍ程度の部材を表面材１０あるいは裏面材１１に固設することや、前記流動物質１４に対して２０〜３０μｍ程度の粒子を混入して用いることが可能であり、このようにスペーサ１２を用いることで、表面材１０と裏面材１１との間に２０〜３０μｍ程度の隙間を形成して磁粉１３の流動を許容するものにしている。又、この磁粉１３の材料として、鉄やニッケルばかりで無く、マグネタイト、ガンマ・ヘクタイトの使用が可能である。そして、この磁気探傷シートＳは、被検査対象１から漏洩した磁束によって磁粉１３が作り出すパターンを認識できるよう構成している。又、前記流動物質１４として、水や灯油等の液体が使用されている。
【００２７】
本発明では、前記磁気探傷シートＳに代えて図４に示すよう構成した磁気探傷シートＳを使用することも可能である。この磁気探傷シートＳは、柔軟で透明な樹脂フィルムで成る上面側の表面材１０と、柔軟な樹脂フィルムで成る下面側の裏面材１１との間に、多数のカプセル部１６を配置し、夫々のカプセル部１６に対して着色した水や灯油等の液体の分散媒１７に分散した磁粉１３（感磁体の一例）を封入している。この磁気探傷シートＳは、従来の技術の後者として示したものと同様に、分散媒１７を磁粉１３と異なる色相に着色することで、視覚によっても磁粉１３の位置を明瞭に把握できるものにしており、磁気が作用した場合には夫々のカプセル部１６の内部において磁粉１３が移動することにより、磁気が作用した部位と作用しない部位との状態を良好に把握できるものにしている。
【００２８】
又、この構造の磁気探傷シートＳを使用する場合には、消磁磁石等を用いてカプセル部１６の内部の磁粉１３を、反被検査対象側面の側に予め移動させておき、この状態で探傷を行うことで、被検査対象１から漏洩した磁束によって対応する部位のカプセル部１６の内部の磁粉１３が移動する現象を、被検査対象１に接触した側の面に現れるパターンから明瞭に把握できるものとなっている。
【００２９】
本発明では、磁気探傷シートＳとして、図３に示したもののように上面側を透明にして（被検査対象１の表面に接する側と反対側の面）から磁粉１３のパターンを捉え得るものや、図４に示すもののように、下面側を透明にして下面側に現れるパターンを把握するよう構成したものの何れの構造のものでも使用可能である。
【００３０】
前記押圧手段Ｐは、図２に示すように、柔軟で透明な樹脂フィルムとして０．１〜０．５ｍｍ程度のフィルム厚のポリエチレンフィルムやポリビニルフィルムを袋状に成型したバッグ２０Ａに対して、ポリビニルアルコールと硼砂とを混合して成るゲル状（スライム状）物質２０Ｂ（水でも良い）を充填したもの、又はゲル状物質（例えば、ポリエチレンとスチレンを共重合させた網状物質を油でゲル化したもの）て柔軟に変形し得る性質となる押圧部材２０と、透明なガラス板、あるいは、良好な透明性を得やすいアクリル樹脂等の素材の樹脂板を平坦に成型して成る圧着板２１とで構成されている。
【００３１】
前記磁気発生機構Ｍは、被検査対象１に接触する一対の磁極３０Ｐ、３０Ｐを有する鉄心３０に銅合金等の良導体のコイル３１を巻回して成る電磁石と、この電磁石のコイル３１に電力を供給する電源３２とで構成されている。
【００３２】
この磁気探傷装置で、被検査対象１として、ガスを貯留するガスホルダや、石油等を貯留するタンク類を構成する鋼板の溶接箇所、あるいは、橋梁等を構成する鋼板の溶接箇所の探傷を行う際の方法は以下のようになる。図１及び図２に示す被検査対象１では、溶接箇所の余盛り１Ａの部位に欠陥Ｃが存在するものと想定しており、この被検査対象１の探傷を行う場合には、同図に示すように、探傷を行うべき部位に磁気探傷シートＳを載置し、この上面に対して押圧部材２０と、圧着板２１とを重ねて載置する。このように載置した状態では、同図に示すように溶接部分において余盛り１Ａが存在しても、その余盛り１Ａの部分に沿う形状に変形して磁気探傷シートＳの下面の全面が被検査対象１の上面に密着し、この磁気探傷シートＳの上面の形状に沿う形状に押圧部材２０の下面が変形して均一の圧力を作用させ、この結果、押圧部材２０の上面が圧着板２１の下面に沿って平坦化する。
【００３３】
このようにセッティングした後に、磁気探傷シートＳを跨ぐ位置に磁極３０Ｐ、３０Ｐを配置する状態で電磁石の姿勢を決めて、その磁極３０Ｐ、３０Ｐを被検査対象に接触させ、コイル３１に対して電源３２から電力を供給して電磁石からの磁界を被検査対象１に作用させることで、鉄心３０からの磁束が被検査対象１の内部に導かれて、鉄心３０と被検査対象１との間に磁気回路が形成され、この磁気回路中に欠陥Ｃが存在すると、その欠陥Ｃの部分での磁束の漏洩量が増大して磁気探傷シートＳの磁粉１３に作用する結果、この漏洩した磁束の方向に沿って磁粉１３が列を成すパターンを作り出し、このパターンと磁束の漏洩量の少ない部分のパターンとを比較することにより、欠陥Ｃの有無を視覚的に、あるいは、カメラで撮影した場合には映像的に把握できるものとなる。
【００３４】
このように第１実施の形態では、柔軟なシート状に形成された磁気探傷シートＳと、柔軟に変形自在であるが圧力を伝え得るよう構成された押圧部材２０と、殆ど変形しない圧着板２１とを組み合わせ、磁気探傷シートＳを被検査対象１の表面に隙間を生ずること無く密着させることを可能にするものとなっている。又、磁気探傷シートＳとして図３に示す構造のものを使用し、例えば、押圧部材２０だけを用いた場合には、凹凸を有する表面を介して磁粉１３のパターンを観察するので光線に屈折によりパターンに歪みを発生させやすいものであるが、本発明では平坦な面を有する圧着板２１を使用するので、磁粉１３のパターンを歪みの少ない状態で観察でき、検査の精度を向上させるものとなっている。
【００３５】
〔第２実施の形態〕
この第２の実施の形態では前記第１実施の形態と同じ機能を有するものには前記第１実施の形態と共通する番号、符号を付している。
【００３６】
図５及び図６に示すように、被検査対象１の表面に接触させる磁気探傷シートＳと、この磁気探傷シートＳを被検査対象１に圧着させる押圧手段Ｐと、被検査対象１に磁気を作用させる磁気発生機構Ｍとを備えて磁気探傷装置が構成されている。この磁気探傷装置は本発明の磁気探傷方法を実現する構成であり、この磁粉対象方法では鉄を代表とする磁性体を被検査対象１とし、具体的には鉄板材の溶接箇所の余盛り部分１Ａや、鉄製の配管の屈曲部分の欠陥Ｃ（クラック等の傷）の検査を行う。
【００３７】
この磁気探傷装置では、磁気探傷シートＳの構造が第１実施の形態において図３に示す構造のものを想定しており、押圧手段Ｐにおいて第１実施の形態の構成に加えて圧着板２１を被検査対象１の側に押し付ける付勢機構ＰＡを付加した点において第１実施例と異なっている。
【００３８】
つまり、押圧手段Ｐは、柔軟で透明な樹脂フィルムとして０．１〜０．５ｍｍ程度の膜圧のポリエチレンフィルムやポリビニルフィルムを袋状に成型したバッグ２０Ａに対して、ポリビニルアルコールと硼砂とを混合して成るゲル状（スライム状）物質２０Ｂ（水でも良い）を充填して柔軟に変形し得る性質となる押圧部材２０と、透明なガラス板、あるいは、良好な透明性を得やすいアクリル樹脂等の素材の樹脂板を平坦に成型して成る圧着板２１と、この圧着板２１を被検査対象の側に押し付けるように、圧力付与機構としての一対のゴムベルト２５を有した付勢機構ＰＡとで構成されている。
【００３９】
前記付勢機構ＰＡは、夫々のゴムベルト２５が、その一方の端部が圧着板２１の一方の端部に連結し、他方の端部が圧着板２１の他方の端部の係脱部２１Ａに分離自在に連結するノブ２６を備えている。又、ノブ２６を人為的に操作することで、このノブ２６を係脱部２１Ａの開放する部位から容易に分離できるものにしており、探傷を行う場合に、磁気探傷シートＳと押圧手段Ｐとを移動させる際に、簡単な操作で付勢力を解除でき、この解除の後には、簡単な操作で再度付勢力を作用させ得るものにしている。
【００４０】
この磁気探傷装置では、被検査対象１としての大径のパイプ類の溶接箇所の探傷を行う場合の使用形態を示しており、この被検査対象１の探傷を行う場合には、検査すべき表面に磁気探傷シートＳを配置し、この磁気探傷シートＳの外面側に押圧部材２０と、圧着板２１とを配置した状態で、ゴムベルト２５をパイプ（被検査対象）に巻き掛けて、このゴムベルト２５からの付勢力を圧着板２１に作用させることで、この圧着板２１をパイプの外面側に引き寄せ、結果として、この圧着板２１からの圧力を押圧部材２０を介して磁気探傷シートＳに作用させて、この磁気探傷シートＳをパイプの外面に密着させるものとなっている。
【００４１】
このようにセッティングした後に、磁気探傷シートＳを跨ぐ位置に磁極３０Ｐ、３０Ｐを配置する状態で電磁石の姿勢を決め、その磁極３０Ｐ、３０Ｐを被検査対象に接触させ、コイル３１に対して電源３２から電力を供給して電磁石からの磁界を被検査対象１に作用させることで、鉄心３０からの磁束が被検査対象１の内部に導かれて、鉄心３０と被検査対象１との間に磁気回路が形成され、この磁気回路中に欠陥Ｃが存在すると、その欠陥Ｃの部分での磁束の漏洩量が増大して磁気探傷シートＳの磁粉１３に作用する結果、この漏洩した磁束の方向に沿って磁粉１３が列を成すパターンを作り出し、このパターンと磁束の漏洩量の少ない部分のパターンとを比較することにより、欠陥Ｃの有無を視覚的に、あるいは、カメラで撮影した場合には映像的に把握できるものとなる。
【００４２】
このように第２実施の形態では、柔軟なシート状に形成された磁気探傷シートＳと、柔軟に変形自在であるが圧力を伝え得るよう構成された押圧部材２０と、殆ど変形しない圧着板２１とを組み合わせ、付勢機構ＰＡから付勢力を作用させることで、被検査対象１の表面の姿勢や表面形状に拘わらず、磁気探傷シートＳを被検査対象１の表面に隙間を生ずること無く密着させることを可能にするものとなっている。又、本第２実施の形態でも第１実施の形態と同様に、例えば、押圧部材２０だけを用いた場合には、凹凸を有する表面を介して磁粉１３のパターンを観察するので光線に屈折によりパターンに歪みを発生させやすいものであるが、本発明では平坦な面を有する押圧板を使用するので、磁粉１３のパターンを歪みの少ない状態で観察でき検査の精度を向上させるものとなっている。尚、この第２実施の形態においても図４に示す構造の磁気探傷シートＳを使用することも可能である。
【００４３】
〔別実施の形態〕
本発明は上記実施の形態以外に、以下のように構成して実施することも可能である。
【００４４】
（イ）第１、第２実施の形態に対応して、押圧部材と、圧着板とを接触部位において予め接着剤等で接着して一体化しておき、これを探傷に使用することや、第１実施の形態に対応して圧着板に対して重量物を取り付けることで、圧着時に重量物の重量を利用する形態で探傷に使用する。
【００４５】
（ロ）磁気探傷シートＳとして、柔軟な樹脂フィルムで成る上面材と、下面側に柔軟で透明な樹脂フィルムで成る裏面材との間に、分散媒に分散した磁粉を封入したものを使用することも可能である。この場合、探傷時には磁気発生機構で発生させた磁気を作用させた後に、この磁気探傷シートＳを捲り上げ、被検査対象と接する面に現れる磁粉のパターンを確認する作業が必要となる。
【００４６】
（ハ）第２実施の形態に対応して、付勢機構としてバネを用いることが可能であり、第２実施の形態のように巻き付けてゴムベルトを使用できない被検査対象として比較的広い面において探傷を行う場合には、図７及び図８に示すように、被検査対象１の表面に粘着テープ２７でゴムベルト２５（圧力付与機構の一例）の端部を貼り付け、このゴムベルト２５からの付勢力を圧着板２１に作用させるよう、ゴムベルト２５と圧着板２１との位置関係をセットする。このように構成することにより、縦姿勢や傾斜姿勢で比較的広い面を有して成る被検査対象１のように、表面に対して重量を作用させて磁気探傷シートＳを押し付けられないものであっても、その表面に対して磁気探傷シートＳを浮き上がりを生ずること無く密接させて探傷を行えるのである。又、粘着テープ２７の代わりに永久磁石、電磁石を使用しても良く、この際に圧着板２１の上から直接加重を掛けても良い。
【図面の簡単な説明】
【図１】第１実施の形態の磁気探傷装置の構成物の配置を示す全体斜視図
【図２】第１実施の形態の磁気探傷装置の構成物の配置を示す断面図
【図３】第１実施の形態の磁気探傷シートの断面図及び一部切欠き平面図
【図４】第１実施の形態の磁気探傷シートの断面図
【図５】第２実施の形態の磁気探傷装置の構成物の配置を示す全体斜視図
【図６】第２実施の形態の磁気探傷装置の構成物の配置を示す断面図
【図７】別実施の形態の磁気探傷装置の構成物の配置を示す断面図
【図８】別実施の形態の磁気探傷装置の構成物の配置を示す斜視図
【符号の説明】
１被検査対象
２０押圧部材
２１圧着板
Ｐ押圧手段
ＰＡ付勢機構
Ｍ磁気発生機構
Ｓ磁気探傷シート[0001]
BACKGROUND OF THE INVENTION
  According to the present invention, a sheet-like flexible magnetic flaw detection sheet enclosing a magnetic sensitive body that forms a pattern corresponding to a magnetic flux density is brought into contact with an object to be inspected, and magnetism generated by a magnetism generation mechanism in this contact state is inspected. Magnetic flaw detection method that detects the magnetic flux leaking from the object to be inspected by acting on the magnetic sensing element of the magnetic flaw detection sheet and performs the flaw detection on the object to be inspected based on the pattern created by this magnetic sensitive elementAnd magnetic flaw detectorAbout.
[0002]
[Prior art]
As techniques similar to the magnetic flaw detection method configured as described above, there are those disclosed in Japanese Patent Laid-Open Nos. 56-40752 and 2001-21539.
[0003]
Among these conventional techniques, the former is a test cassette (not in sheet form) filled with a suspension of water, kerosene, and magnetic powder in a container having a transparent top and side surfaces and a non-conductive elastic thin film at the bottom. Corresponds to the magnetic flaw detection sheet of the present invention), and the magnetizing device (of the present invention) is applied to the object to be inspected in a state where the bottom portion (non-conductive elastic thin film) of the inspection cassette is in contact with the object to be inspected. Magnetic force can be applied from the magnetic generation mechanism), and the state of magnetic flux leaked from the structure under inspection (inspected object of the present invention) can be grasped by the pattern of magnetic particles inside the cassette and the state of the defective part of the structure under inspection can be grasped I have to. Further, when the inspection cassette is brought into contact with the structure to be inspected, the thin film on the lower surface is deformed so as to follow the surface shape of the structure to be inspected, so that the thin film adheres to the surface of the structure to be inspected. Yes.
[0004]
Among the conventional techniques, the latter has a large number of chambers between two transparent sheets, and a magnetic sheet (magnetic flaw detection sheet of the present invention) is filled with a white dispersion medium in which magnetic powder is dispersed in each chamber. ). In this magnetic sheet, the magnetic powder in the small chamber is moved uniformly to one side of the sheet by applying a magnetic force from the demagnetizing magnet, and then the magnetic powder moves in the small chamber when the magnetic force is applied thereafter. It can be observed from the magnetic powder pattern. In this conventional technique, as a batch type magnetic particle flaw detector, the spring force from a large number of springs acts on the magnetic sheet in a state where the magnetic sheet is in contact with the inspection object (inspection object of the present invention). By doing so, the magnetic sheet and the test object can be brought into close contact with each other. Since a pattern appears on the surface of the magnetic sheet in contact with the object to be inspected, it is necessary to check the pattern in a form in which the magnetic sheet is lifted up during the flaw detection.
[0005]
[Problems to be solved by the invention]
Considering that inspection (flaw detection) is performed using a magnetic flaw detection sheet in which magnetic powder is enclosed in a container, like the inspection cassette shown in the former prior art (Japanese Patent Laid-Open No. 56-40752), this magnetic flaw detection is considered. Since the sheet functions under the action of magnetism, the magnetic flaw detection sheet is brought into close contact with the surface of the object to be inspected (conventional structure to be inspected in the prior art) on the ground as well as underwater inspection. Inspection is important in terms of improving inspection accuracy. However, in an operation in which the worker presses with his / her hand to make contact, not only uniform contact can be performed, but also the operator is burdened.
[0006]
Therefore, it is conceivable to use the technique shown in the batch type magnetic particle flaw detector shown in the latter of the conventional techniques (Japanese Patent Laid-Open No. 2001-21539). In this technique, the pressing force from a large number of springs is applied to the magnetic sheet (the magnetic flaw detection sheet of the present invention) to bring the magnetic sheet into close contact with the inspection object (the inspection target of the present invention). However, since a relatively large number of springs are used, the number of parts increases and the flaw detection equipment tends to become complicated. Since the pressure is high in the vicinity of the portion where the urging force directly acts and the pressure is low in the vicinity thereof, there is room for improvement in terms of difficulty in performing uniform pressure contact. In particular, since this inspection is often used to detect defects in the welded part, it is greatly bent like an object to be inspected with a large level difference in surface irregularities such as a surplus part in the welded part or pipes. There is a surface that is difficult to deal with the object to be inspected with a spring.
[0007]
When flaw detection is performed, if the bottom surface of the magnetic flaw detection sheet is lifted from the inspection surface to be inspected, even if the lift amount (lift-off amount) is about 0.1 mm, inspection may become impossible. In many respects, a technique for achieving good adhesion performance is desired from such a viewpoint.
[0008]
An object of the present invention is to rationally configure an inspection method in which a magnetic flaw detection sheet is brought into intimate contact with the surface of an object to be inspected to perform inspection by magnetism.
[0009]
[Means for Solving the Problems]
  Magnetic flaw detection method according to claim 1 of the present inventionAnd a magnetic flaw detector according to claim 6The features, functions and effects are as follows.
〔Characteristic〕
  Features of the magnetic flaw detection method of the present invention are as follows:A sheet-like flexible magnetic flaw detection sheet enclosing a magnetic sensitive material that forms a pattern corresponding to the magnetic flux density is brought into contact with the object to be inspected, and in this contact state, the magnetism generated by the magnetism generating mechanism is applied to the object to be inspected. In the magnetic flaw detection method in which the magnetic flux leaking from the inspection object is captured by the magnetic sensor of the magnetic flaw detection sheet and the inspection target is flawed based on the pattern created by the magnetic detection substance, the magnetic flaw detection sheet is brought into contact with the inspection target. In this state, against the side of the object to be inspected,Consists of transparent gel materialA pressing member that can be deformed flexibly is arranged, and against this pressing memberConsists of a transparent plate-shaped crimping plateThis is in that flaw detection is performed on the inspection object in a state where the magnetic flaw detection sheet is pressed against the inspection object by applying pressure from the pressure applying mechanism.
A feature of the magnetic flaw detector of the present invention is that it is brought into contact with the object to be inspected, and a flexible magnetic flaw detection sheet enclosing a magnetic sensitive body that forms a pattern corresponding to the magnetic flux density, and a magnetic pole are brought into contact with the object to be inspected. In a state of being in a state of being in contact, the magnetism generating mechanism that causes magnetism to act on the object to be inspected, and the magnetic flaw detection sheet in contact with the object to be inspected are arranged with respect to the opposite side of the object to be inspected A pressing member that is made of a transparent gel-like substance and can be flexibly deformed, and a transparent plate that presses the magnetic flaw detection sheet against the object to be inspected by applying pressure to the pressing member. And a pressure applying mechanism constituted by a pressure-bonding plate.
[0010]
[Action / Effect]
  According to the above feature, when flaw detection is performed, a magnetic flaw detection sheet that is in the form of a sheet is brought into contact with the surface of the inspection target, and the pressing member is in contact with the side surface of the magnetic flaw detection sheet that is opposite to the inspection target. Since pressure is applied from the pressure applying mechanism, a uniform pressure is applied to the wide surface in a state in which the pressing member is deformed and in close contact with the side surface to be inspected of the magnetic flaw detection sheet via the wide surface. The magnetic flaw detection sheet can be brought into close contact with the surface to be inspected by this uniform pressure. As a result, the magnetic flaw detection sheet can be brought into close contact with each other on a wide surface without causing the magnetic flaw detection sheet to lift from the object to be inspected by simply using a means for applying pressure to the magnetic flaw detection sheet via a pressing member that can be flexibly deformed. Highly accurate method for flaw detectionAnd equipmentWas reasonably structured.
[0012]
Also,For bags made of flexible resin film,Consists of transparent gel materialA pressing member made of a material that can be deformed flexibly has a performance to transmit pressure well although it can be deformed flexibly, and a pressing member using a pressure plate as a pressure applying mechanism is not greatly deformed. On the other hand, pressure is applied. As a result, when performing flaw detection, it is only necessary to place a magnetic flaw detection sheet on the upper surface of the object to be inspected, and to place a pressing member and a crimping plate on the upper surface of this magnetic flaw detection sheet. Can be done.
[0014]
Furthermore, it can be flexibly deformed composed of gel-like substancesWith a pressing memberConsists of a plate-like crimp plateSince the pressure application mechanism is transparent, the state of the magnetic powder of the magnetic flaw detection sheet brought into contact with the surface of the object to be inspected can be visually grasped by the light beam transmitted through the pressing member and the pressure application mechanism. As a result, flaw detection can be performed without performing an operation such as raising the magnetic flaw detection sheet to expose the surface on the inspection object side.
[0015]
  Of the present inventionClaim 2The characteristics, operations and effects of the magnetic flaw detection method according to the above are as follows.
〔Characteristic〕
  Claim 1In the magnetic flaw detection method described above, the magnetic flaw detection sheet is a sheet in which a flexible upper sheet material and a flexible lower sheet material are overlapped, and a magnetic powder dispersed in a dispersion medium as the magnetosensitive material is enclosed therebetween. The point is that it is shaped into a shape.
[0016]
[Action / Effect]
According to the above characteristics, since magnetic particles exist in the part sandwiched between the flexible upper and lower sheet materials, the entire magnetic flaw detection sheet can be thinned to increase the sensitivity during flaw detection, and at the same time, the entire magnetic flaw detection sheet can be flexibly deformed. When performing a flaw detection, the magnetic flaw detection sheet is brought into contact with the object to be inspected, and only by overlapping the pressing member and the crimping plate, the magnetic flaw detection sheet is brought into close contact with the surface of the inspection object. Magnetic flux from the object to be inspected is captured with high sensitivity by magnetic powder. As a result, the flaw detection can be performed efficiently while the magnetic flaw detection sheet is easy to handle.
[0017]
  Of the present inventionClaim 3The characteristics, operations and effects of the magnetic flaw detection method according to the above are as follows.
〔Characteristic〕
  Claim 1In the magnetic flaw detection method described above, the magnetic flaw detection sheet forms a large number of capsule portions between a flexible upper surface sheet material and a flexible lower surface sheet material, and serves as a dispersion medium for each capsule portion. It is in a point that the dispersed magnetic powder is enclosed.
[0018]
[Action / Effect]
According to the above feature, since the magnetic flaw detection sheet is configured by enclosing magnetic powder dispersed in a dispersion medium in a large number of capsule parts, when flaw detection is performed, the magnetic flaw detection sheet is formed by movement of the magnetic powder in each capsule part. Flaw detection can be performed based on the pattern. In other words, as with the latter of the prior art, when magnetism is applied, the pattern is formed by the magnetic powder sealed in the capsule, so that the contrast can be increased relatively easily while eliminating the magnetic powder bias in the entire magnetic flaw detection sheet. It is possible to form a pattern that will be in a state of contact. As a result, it was possible to perform flaw detection by forming a pattern that was easy to grasp visually.
[0019]
  Of the present inventionClaim 4The characteristics, operations and effects of the magnetic flaw detection method according to the above are as follows.
〔Characteristic〕
  Claim 2 or 3In the described magnetic flaw detection method, at least one of the sheet material on the upper surface side and the sheet material on the lower surface side is transparent.
[0020]
[Action / Effect]
According to the above feature, the magnetic powder pattern in the magnetic flaw detection sheet or the magnetic powder pattern enclosed in the capsule portion can be visually grasped from the transparent side of the sheet material on the upper surface side or the sheet material on the lower surface side. In addition, for example, when the sheet material on the upper surface side and the lower surface side is transparent, it is possible to easily position the inspection surface to be inspected and the magnetic inspection sheet. As a result, reliable flaw detection is realized with a simple operation.
[0021]
  Of the present inventionClaim 5The characteristics, operations and effects of the magnetic flaw detection method according to the above are as follows.
〔Characteristic〕
  In any one of Claims 1-4In the magnetic flaw detection method described above, the pressure applying mechanism uses an elastic force of a spring material or a rubber material and an attracting force by a magnetic force.
[0022]
[Action / Effect]
According to the above feature, since the elastic force from the spring material or rubber material, or the attractive force due to the magnetic force is applied, for example, even if the surface (inspection surface) of the object to be inspected is in an oblique posture or a vertical posture, It is also possible to perform flaw detection by bringing a magnetic flaw detection sheet into close contact with the surface of the inspection object. As a result, the flaw detection can be performed satisfactorily regardless of the posture of the surface of the inspection object.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
As shown in FIGS. 1 and 2, a magnetic flaw detection sheet S that is brought into contact with the surface of the inspection object 1, a pressing means P that presses the magnetic flaw detection sheet S against the inspection object 1, and magnetism is applied to the inspection object 1. The magnetic flaw detection apparatus is configured to include the magnetic generation mechanism M to be actuated. This magnetic flaw detection apparatus has a typical configuration for realizing the magnetic flaw detection method of the present invention. In this magnetic flaw detection method, a magnetic body typified by iron is used as an inspection object 1, specifically, an iron plate material is welded. This is for inspecting an extra portion 1A of the portion and a defect C (scratches such as cracks) in the curved surface portion of the steel pipe. The surplus portion 1A is assumed to have a general form having a width of about 10 mm and a raised height of about 1 mm from the object 1 to be inspected.
[0024]
As shown in FIG. 3, the magnetic flaw detection sheet S includes a top surface material 10 made of a flexible and transparent resin film and a back material 11 on the bottom surface made of a flexible resin film. Using a container formed into a flexible sheet shape in which a gap d of about 20 to 30 μm is formed by interposing a plurality of spacers 12 between each other, and about 0.1 μm or more with a magnetic material for this container, A particulate magnetic powder 13 (an example of a magnetic sensitive body) having a particle size sufficiently smaller than the gap value (about 20 to 30 μm) and a gas or fluid fluid substance 14 (an example of a dispersion medium) are enclosed. Configured. Further, the container for the magnetic flaw detection sheet S has a sealed structure by joining the outer peripheral portions of the front surface material 10 and the back surface material 11 using a heat welding technique or an adhesive, and the magnetic powder 13 has a fluorescent structure. A material coated may be used.
[0025]
Specifically, the film thickness of the surface material 10 and the back material 11 is about 0.02 to 0.5 mm, and it is essential that the surface material 10 of the container is transparent, Some colored material may be used, and the back material 11 does not need to be transparent, and a colored resin can also be used. Polyethylene, polyvinyl, or PET (polyethylene terephthalate) resin can be used as the surface material 10 and the back material 11, and soft magnetic austenitic stainless steel foil can be used as the back material 11 instead of the resin film. Is also possible.
[0026]
The spacer 12 can be used by fixing a member of about 20 to 30 μm to the surface material 10 or the back surface material 11, or by mixing particles of about 20 to 30 μm with respect to the fluid substance 14, By using the spacer 12 in this way, a gap of about 20 to 30 μm is formed between the front surface material 10 and the back surface material 11 to allow the magnetic powder 13 to flow. Further, as the material of the magnetic powder 13, not only iron and nickel but also magnetite and gamma-hectite can be used. And this magnetic testing sheet S is comprised so that the pattern which the magnetic powder 13 produces with the magnetic flux which leaked from the to-be-inspected object 1 can be recognized. The fluid substance 14 is a liquid such as water or kerosene.
[0027]
In the present invention, it is possible to use a magnetic flaw detection sheet S configured as shown in FIG. 4 in place of the magnetic flaw detection sheet S. In this magnetic flaw detection sheet S, a large number of capsule portions 16 are arranged between an upper surface material 10 made of a flexible and transparent resin film and a lower surface material 11 made of a flexible resin film. A magnetic powder 13 (an example of a magnetic sensitive body) dispersed in a liquid dispersion medium 17 such as colored water or kerosene is enclosed in the capsule portion 16. In the same manner as the latter of the prior art, this magnetic flaw detection sheet S is colored in a different hue from the magnetic powder 13 so that the position of the magnetic powder 13 can be clearly grasped visually. In addition, when magnetism acts, the magnetic powder 13 moves inside each capsule part 16 so that the state of the part where the magnetism acts and the part where the magnetism does not act can be grasped well.
[0028]
Further, when using the magnetic flaw detection sheet S having this structure, the magnetic powder 13 inside the capsule portion 16 is moved in advance to the side of the object to be inspected using a demagnetizing magnet or the like, and in this state, the flaw detection is performed. By performing the above, it is possible to clearly grasp the phenomenon in which the magnetic powder 13 inside the capsule portion 16 at the corresponding site moves due to the magnetic flux leaked from the test object 1 from the pattern appearing on the surface in contact with the test object 1. It has become a thing.
[0029]
In the present invention, the magnetic flaw detection sheet S can capture the pattern of the magnetic powder 13 from the transparent upper surface (the surface opposite to the side in contact with the surface of the inspection object 1) as shown in FIG. As shown in FIG. 4, any structure can be used which is configured to grasp the pattern appearing on the lower surface side by making the lower surface side transparent.
[0030]
As shown in FIG. 2, the pressing means P is a polyvinyl chloride for a bag 20 </ b> A in which a polyethylene film or a polyvinyl film having a film thickness of about 0.1 to 0.5 mm is molded into a bag shape as a flexible and transparent resin film. A gel-like (slime-like) substance 20B (which may be water) filled with alcohol and borax or a gel-like substance (for example, a net-like substance obtained by copolymerizing polyethylene and styrene is gelled with oil. A pressing member 20 having a property that can be flexibly deformed, and a pressure plate 21 formed by flatly molding a transparent glass plate or a resin plate made of a material such as an acrylic resin that easily obtains good transparency. It is configured.
[0031]
The magnetism generating mechanism M supplies an electromagnet formed by winding a coil 31 made of a good conductor such as a copper alloy around an iron core 30 having a pair of magnetic poles 30P and 30P in contact with an object 1 to be inspected, and supplies the coil 31 with the electromagnet 31. And a power source 32.
[0032]
With this magnetic flaw detector, as the object 1 to be inspected, flaw detection is performed on a welded portion of a steel plate constituting a gas holder for storing gas or a tank for storing oil or the like, or a welded portion of a steel plate constituting a bridge or the like. The method is as follows. In the inspection object 1 shown in FIGS. 1 and 2, it is assumed that a defect C exists in the area of the surplus 1A of the welded portion. As shown, a magnetic flaw detection sheet S is placed at a site where flaw detection is to be performed, and a pressing member 20 and a pressure-bonding plate 21 are placed on the upper surface. In the state of being placed in this manner, even if the surplus 1A is present in the welded portion as shown in the figure, it is deformed to a shape along the surplus 1A portion, and the entire lower surface of the magnetic flaw detection sheet S is covered. The upper surface of the test object 1 is in close contact with the upper surface of the magnetic testing sheet S, and the lower surface of the pressing member 20 is deformed into a shape that conforms to the shape of the upper surface of the magnetic testing sheet S. Flatten along the lower surface of the substrate.
[0033]
After setting in this way, the posture of the electromagnet is determined in a state where the magnetic poles 30P and 30P are arranged in a position straddling the magnetic testing sheet S, the magnetic poles 30P and 30P are brought into contact with the object to be inspected, and the coil 31 is powered. By supplying electric power from 32 and causing the magnetic field from the electromagnet to act on the inspection object 1, the magnetic flux from the iron core 30 is guided to the inside of the inspection object 1, and between the iron core 30 and the inspection object 1. When a magnetic circuit is formed and a defect C exists in the magnetic circuit, the amount of magnetic flux leakage at the defect C increases and acts on the magnetic powder 13 of the magnetic flaw detection sheet S. As a result, the direction of the leaked magnetic flux A pattern in which the magnetic powder 13 forms a line along the line and the pattern is compared with a pattern of a portion with a small amount of magnetic flux leakage to visually detect the presence or absence of the defect C or with a camera. The ones that can be grasped iconic in the case.
[0034]
As described above, in the first embodiment, the magnetic flaw detection sheet S formed in a flexible sheet shape, the pressing member 20 configured to be able to flexibly deform but transmit pressure, and the pressure-bonding plate 21 that hardly deforms. In combination, the magnetic flaw detection sheet S can be brought into close contact with the surface of the inspection object 1 without causing a gap. 3 is used as the magnetic flaw detection sheet S. For example, when only the pressing member 20 is used, the pattern of the magnetic powder 13 is observed through the surface having irregularities. Although it is easy to generate | occur | produce distortion in a pattern, since the crimping board 21 which has a flat surface is used in this invention, the pattern of the magnetic powder 13 can be observed in a state with few distortions, and the precision of a test | inspection is improved. ing.
[0035]
[Second Embodiment]
In the second embodiment, components having the same functions as those in the first embodiment are given the same numbers and symbols as those in the first embodiment.
[0036]
As shown in FIGS. 5 and 6, a magnetic flaw detection sheet S that is brought into contact with the surface of the inspection object 1, a pressing means P that presses the magnetic flaw detection sheet S against the inspection object 1, and magnetism is applied to the inspection object 1. The magnetic flaw detection apparatus is configured to include the magnetic generation mechanism M to be actuated. This magnetic flaw detection apparatus is configured to realize the magnetic flaw detection method of the present invention. In this magnetic powder target method, a magnetic material typified by iron is used as an inspection target 1, and specifically, an extra portion of a welded portion of an iron plate material. 1A and defects C (scratches such as cracks) at the bent portion of the steel pipe are inspected.
[0037]
In this magnetic flaw detector, the structure of the magnetic flaw detection sheet S is assumed to be that shown in FIG. 3 in the first embodiment, and the pressing means P is provided with a pressure plate 21 in addition to the structure of the first embodiment. The second embodiment is different from the first embodiment in that an urging mechanism PA that is pressed to the inspection object 1 side is added.
[0038]
That is, the pressing means P mixes polyvinyl alcohol and borax to a bag 20A obtained by molding a polyethylene film or polyvinyl film having a film pressure of about 0.1 to 0.5 mm as a flexible and transparent resin film into a bag shape. A pressing member 20 that is filled with a gel-like (slime-like) material 20B (which may be water) and can be flexibly deformed, a transparent glass plate, or an acrylic resin that easily obtains good transparency A pressure-bonding plate 21 formed by flatly molding a resin plate made of the above material, and an urging mechanism PA having a pair of rubber belts 25 as a pressure applying mechanism so as to press the pressure-bonding plate 21 against the inspection object side. It is configured.
[0039]
In the urging mechanism PA, each rubber belt 25 has one end connected to one end of the crimping plate 21 and the other end connected to the engaging / disengaging portion 21A of the other end of the crimping plate 21. A knob 26 is provided for detachable connection. Further, the knob 26 can be easily separated from the open portion of the engaging / disengaging portion 21A by manipulating the knob 26. When performing flaw detection, the magnetic flaw detection sheet S, the pressing means P, When moving the urging force, the urging force can be released by a simple operation, and after this release, the urging force can be applied again by a simple operation.
[0040]
This magnetic flaw detector shows a usage pattern in the case where flaw detection is performed on a welded portion of a large-diameter pipe as the inspection object 1, and the surface to be inspected when flaw detection is performed on the inspection object 1. A magnetic flaw detection sheet S is disposed on the outer surface of the magnetic flaw detection sheet S, and a rubber belt 25 is wound around a pipe (inspected object) in a state where the pressing member 20 and the pressure bonding plate 21 are disposed. By applying the urging force from the pressure plate 21 to the pressure plate 21, the pressure plate 21 is drawn toward the outer surface of the pipe, and as a result, the pressure from the pressure plate 21 is applied to the magnetic flaw detection sheet S via the pressing member 20. The magnetic flaw detection sheet S is brought into close contact with the outer surface of the pipe.
[0041]
After the setting as described above, the orientation of the electromagnet is determined in a state where the magnetic poles 30P and 30P are arranged at a position straddling the magnetic flaw detection sheet S, the magnetic poles 30P and 30P are brought into contact with the object to be inspected, and the power source 32 is supplied to the coil 31. By supplying electric power from the electromagnet and causing the magnetic field from the electromagnet to act on the object 1 to be inspected, the magnetic flux from the iron core 30 is guided to the inside of the object 1 to be inspected and magnetized between the iron core 30 and the object 1 to be inspected. When a circuit is formed and a defect C exists in the magnetic circuit, the amount of magnetic flux leakage at the portion of the defect C increases and acts on the magnetic powder 13 of the magnetic flaw detection sheet S. As a result, in the direction of the leaked magnetic flux A pattern in which magnetic particles 13 form a row along the line, and by comparing this pattern with a pattern of a portion with a small amount of magnetic flux leakage, the presence or absence of the defect C is visually or photographed with a camera. The ones that can be grasped iconic in.
[0042]
As described above, in the second embodiment, the magnetic flaw detection sheet S formed in a flexible sheet shape, the pressing member 20 configured to be able to transmit pressure flexibly while being deformable, and the pressure-bonding plate 21 hardly deformed. , And applying an urging force from the urging mechanism PA, the magnetic flaw detection sheet S is brought into close contact with the surface of the object 1 to be inspected without generating a gap, regardless of the posture or surface shape of the object 1 to be inspected. It is possible to make it. Also in the second embodiment, similarly to the first embodiment, for example, when only the pressing member 20 is used, the pattern of the magnetic powder 13 is observed through the surface having irregularities, so that the light beam is refracted. Although it is easy to generate | occur | produce distortion in a pattern, in this invention, since the press plate which has a flat surface is used, the pattern of the magnetic powder 13 can be observed in a state with few distortions, and the precision of a test | inspection is improved. . In the second embodiment, it is also possible to use the magnetic flaw detection sheet S having the structure shown in FIG.
[0043]
[Another embodiment]
In addition to the above embodiments, the present invention can be configured and implemented as follows.
[0044]
(A) Corresponding to the first and second embodiments, the pressing member and the crimping plate are previously bonded and integrated with an adhesive or the like at the contact site, and this is used for flaw detection, By attaching a heavy object to the crimping plate corresponding to one embodiment, it is used for flaw detection in a form that utilizes the weight of the heavy object at the time of crimping.
[0045]
(B) A magnetic flaw detection sheet S in which magnetic powder dispersed in a dispersion medium is encapsulated between an upper surface material made of a flexible resin film and a back surface material made of a flexible and transparent resin film on the lower surface side is used. It is also possible. In this case, it is necessary to work up the magnetic flaw detection sheet S after applying the magnetism generated by the magnetism generation mechanism at the time of flaw detection and confirm the pattern of magnetic particles appearing on the surface in contact with the object to be inspected.
[0046]
(C) Corresponding to the second embodiment, it is possible to use a spring as an urging mechanism, and the flaw detection is performed on a relatively wide surface as an object to be inspected that cannot be wrapped and used with a rubber belt as in the second embodiment. 7 and 8, the end of a rubber belt 25 (an example of a pressure applying mechanism) is attached to the surface of the inspection object 1 with an adhesive tape 27, and the biasing force from the rubber belt 25 is applied. The positional relationship between the rubber belt 25 and the pressure-bonding plate 21 is set so as to act on the pressure-bonding plate 21. With this configuration, the magnetic flaw detection sheet S cannot be pressed by applying a weight to the surface, like the inspection object 1 having a relatively wide surface in a vertical posture or an inclined posture. Even in such a case, the flaw detection can be carried out by bringing the magnetic flaw detection sheet S into close contact with the surface without causing any lift. Further, a permanent magnet or an electromagnet may be used in place of the adhesive tape 27. At this time, a load may be applied directly from above the pressure plate 21.
[Brief description of the drawings]
FIG. 1 is an overall perspective view showing an arrangement of components of a magnetic flaw detector according to a first embodiment.
FIG. 2 is a sectional view showing the arrangement of components of the magnetic flaw detector according to the first embodiment.
FIG. 3 is a sectional view and a partially cutaway plan view of the magnetic flaw detection sheet according to the first embodiment.
FIG. 4 is a sectional view of the magnetic flaw detection sheet according to the first embodiment.
FIG. 5 is an overall perspective view showing the arrangement of components of the magnetic flaw detector according to the second embodiment.
FIG. 6 is a cross-sectional view showing the arrangement of components of the magnetic flaw detector according to the second embodiment.
FIG. 7 is a sectional view showing the arrangement of components of a magnetic flaw detector according to another embodiment.
FIG. 8 is a perspective view showing the arrangement of components of a magnetic flaw detector according to another embodiment.
[Explanation of symbols]
1 Inspected subject
20 Pressing member
21 Crimp plate
P pressing means
PA energizing mechanism
M Magnetic generation mechanism
S Magnetic inspection sheet

Claims

A sheet-like flexible magnetic flaw detection sheet enclosing a magnetic sensitive material that forms a pattern corresponding to the magnetic flux density is brought into contact with the object to be inspected, and the magnetism generated by the magnetism generating mechanism is applied to the object under inspection in this contact state. A magnetic flaw detection method for detecting a magnetic flux leaking from a test object with a magnetic sensor of a magnetic flaw detection sheet and performing a test of the test object based on a pattern created by the magnetic sensor,
With the magnetic flaw detection sheet in contact with the object to be inspected, a pressing member that can be flexibly deformed and is made of a transparent gel material is disposed on the side surface to be inspected of the object to be inspected. A magnetic flaw detection method in which flaw detection is performed on a test object in a state in which the magnetic flaw detection sheet is pressed against the test object by applying pressure from a pressure applying mechanism configured by a transparent plate-shaped pressure-bonding plate to the pressing member.

The magnetic flaw detection sheet is formed into a sheet shape in which a flexible sheet material on the upper surface side and a flexible sheet material on the lower surface side are overlapped, and magnetic powder dispersed in a dispersion medium as the magnetosensitive material is enclosed therebetween. The magnetic flaw detection method according to claim 1 .

The magnetic flaw detection sheet forms a large number of capsule portions between a flexible upper surface sheet material and a flexible lower surface sheet material, and encapsulates magnetic powder dispersed in a dispersion medium in each capsule portion. The magnetic flaw detection method according to claim 1, wherein the magnetic flaw detection method is configured.

The magnetic flaw detection method according to claim 2 or 3, wherein at least one of the sheet material on the upper surface side and the sheet material on the lower surface side is transparent.

The magnetic flaw detection method according to any one of claims 1 to 4, wherein the pressure applying mechanism uses an elastic force of a spring material or a rubber material and an attracting force by a magnetic force.

  A flexible magnetic flaw detection sheet that is in contact with the object to be inspected and encloses a magnetic sensing element that forms a pattern corresponding to the magnetic flux density;
  A magnetism generating mechanism that causes magnetism to act on the object to be inspected in a state where a magnetic pole is in contact with the object to be inspected;
  In a state where the magnetic testing sheet is in contact with the object to be inspected, the magnetic flaw detection sheet is arranged with respect to the side surface of the object to be inspected, and can be flexibly deformed made of a transparent gel substance. A pressing member;
  A pressure applying mechanism constituted by a transparent plate-like pressure-bonding plate that presses the magnetic flaw detection sheet against the object to be inspected by applying pressure to the pressing member;
Magnetic flaw detector with