JP2004093195A

JP2004093195A - Weld bead cut shape measuring method of electro-resistance-welded tube and measuring device

Info

Publication number: JP2004093195A
Application number: JP2002251269A
Authority: JP
Inventors: Toshibumi Kodama; 児玉　俊文
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 2002-08-29
Filing date: 2002-08-29
Publication date: 2004-03-25

Abstract

<P>PROBLEM TO BE SOLVED: To easily discriminate from a step part caused by cutting, an image processing abnormal portion caused by that, even when the SN ratio is extremely lowered as in the case where the brightness of an optically-cut image in optically-cut images collected at the measuring time is extremely lowered up to the same degree as the brightness of a region (formation part) other than the image, or the like. <P>SOLUTION: An image formed by superposing the optically-cut image on an image acquired after narrowing lines of the optically-cut image by a prescribed image processing means is displayed. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は電縫溶接管の溶接ビード切削形状の計測方法および計測装置に関する。
【０００２】
【従来の技術】
一般に、電縫溶接管（以下、本文中では略して「電縫管」と称している箇所がある）たとえば電縫鋼管は、鋼帯（鋼板を含む）を管状に整形しながら搬送し、鋼帯両幅端を高周波誘導加熱圧接や抵抗加熱圧接等の手段で鋼帯長手方向に連続的に突き合わせ溶接することによって製造されている。
【０００３】
この電縫管の溶接部には、圧接による盛り上がり、すなわちビードが管内外面に生じるが、通常このビードは製造ライン中、溶接機よりも下流に設置された切削バイトにより鋼帯長手方向に連続的に切削される。ビード部を切削除去後の同部の形状（以下、ビード切削形状と称す）は、理想的には鋼帯母材部の輪郭形状と一体化しビード部がどこであったかわからなくなることが望ましく、可及的にそれに近づけるため切削バイト先端を電縫管表面の適切な位置に保持する必要がある。
【０００４】
このため、従来より、切削開始時点で、作業員が目視判定やマイクロメータ等で切削部の厚み計測等を行って、切削バイトを最適位置に調整するようにしていたが、何本もの電縫管を製造するうちに、種々の理由から切削バイトの位置ずれや切削バイトの刃が欠けるなどして、製品電縫管にビード削り残しや深削りなどの切削不良が発生する場合があった。
【０００５】
このような切削不良は製品電縫管の外観を損なうだけでなく、このような切削不良部を有する管をガスライン等の加圧配管に適用すると、最悪の場合、管破裂に至る危険がある。
【０００６】
したがって、ビード切削形状を管の製造中に計測して監視し、その結果に応じて切削バイト位置を適宜修正する必要がある。
【０００７】
しかしながら、ビード切削形状の監視は、外から観察しやすい管外面であっても作業員の目視観察に頼らざるを得ないため、精度や再現性に欠けるなど、定量性や信頼性に疑問がある。
【０００８】
管内面に関してはラインの構成上製造中はビード部を直接観察することができず、ラインの最終位置において管を切断した時点で端部を観察したり、あるいは運転を中断して管のビード位置の部分をガス溶断してサンプリングし、その内面を観察する、等の方法で対処しているが、前者の方法では、観察位置が切削位置より数十ｍ以上下流であるため、切削に異常が発生した場合でもこれを検知するまでに発生する不良部の長さが長くなって歩留まりが低下するという問題があった。また、後者においては、ライン停止に伴って切削バイトを逃がさないと摩擦熱で焼き付く等の問題があるため、ラインの運転を再開してもビード切削形状に段差ができる等して歩留まりが低下する上に、ラインを停止させねばならず、生産能率も低下するという問題があった。またこの両者とも管軸方向の一部分を検査するだけのため、製品全長の品質保証を行うという品質管理体制には応じることができないという問題があった。
【０００９】
これらの問題を解決するため、半自動的なビード切削形状計測方法として、光切断法を用いた方法が従来より提案されている。ここで光切断法とは、たとえば特開昭５７−１０８７０５号公報に登場するが、図１４のように被測定物である電縫鋼管（単に電縫管とも称する）１００に光源１によりスリット光２を照射し、カメラ３で入射角度αと異なる角度βから観察すると、被測定物の表面形状にしたがって変形されたスリット像（光切断像）が観察され、この光切断像と観測光学系の幾何学的配置から物体（例えばビート部１１）形状を算出するものであり、観測光学系が単純であること、測定感度が観測光学系の幾何学的配置によって幅広く変化させられること、などの利点がある。ちなみにスリット光の照射領域から外れる領域のことを地合（ぢあい）部という。
【００１０】
そしてまた、例えば特開昭５２−９６０４９号公報に開示の技術では、切削しない溶接ビード部を光切断法で観察し、表示モニタに光学配置によって定まる拡大比に応じた目盛をつけるビード形状観察方法が提案されている。
【００１１】
しかしながら、これらの方法はいずれも計測画像（光切断画像）を表示するまでであり、ビード切削形状の判定はモニタを作業者が目視判定することで行っており、自動計測には至っていない。
【００１２】
またこの点、自動計測のための定量方法としては、例えば、特許２６１８３０３号公報に開示のような技術があった。それによれば、電縫管の溶接ビード切削後の形状を計測する際にスリット光とＩＴＶカメラによる光切断画像をもって鋼管ビード切削部の映像を捕らえ、その断面形状映像（光切断像）を細線化処理（一画素が一方向につながっている領域を細線に見たてること）して断面形状を算出し、その断面形状の輝度により切削部と非切削部である母材を区別し、その区別した切削部中央値と切削部右端の値及び切削部左端の値とを求め、この三つの計測値をもとに切削深さ量や切削傾き量を算出するような方法が提案されている。
【００１３】
【発明が解決しようとする課題】
しかしながら、特許２６１８３０３号公報に開示の技術おいては、細線化処理の具体的な方法として、光切断画像から得られる管軸と平行な方向（Ｙ軸方向）の最大輝度を管周方向（素材鋼板や鋼帯にとってはその幅方向に相当するため以下幅方向と称す）に伸びるＸ軸上の該当各座標に対しプロットするという具合に、輝度を直接Ｙ軸座標に置き換える演算を行っているのみであるため、正確な断面形状が得られない場合がある、という問題点がある。
【００１４】
これについて詳述するが、発明者らが製造現場で実験を重ねた経験によると、切削直後の電縫管の同部の表面は鏡面状態になっている一方で、周囲の非切削部は酸化膜等が付着していて黒っぽいために、スリット光の乱反射の度合いが異なる。このため、ビード切削部の光切断像の輝度は幅方向に同程度であるとは限らない。例えば図１５のように切削部のスリット光はほとんど正反射（入射角と同じ角度で入射方向と正反対の方向に反射すること）してしまって、その輝度は非切削部の１０分の１以下となる場合がある。入射角と受光角が異なっていると、このような正反射光は却って低輝度に見えるからである。
【００１５】
このような場合には光切断像はノイズに埋もれてしまい、ビード切削形状はうまく得られない。ＩＴＶカメラなどの観測光学系のゲインを高めるか露光時間を長くするなどして切削部の輝度を高めようとすると、今度は図１６右部のように非切削部が前述のカメラなどの観測光学系の仕様上の最大輝度を超えるレンジオーバー（ハレーション）を起こして正確な非切削部の形状を判別できなくなるのである。その理由は、このような輝度のレンジオーバーが発生した場合、光切断像中の非切削部では、最大輝度を示す管軸方向座標（Ｙ軸座標）が複数現れ、最大輝度を示す管軸方向座標（Ｙ軸座標）を一意に決定できないからである。
【００１６】
発明者らは先に、このような問題点を解決するため、特願２００２−１２８４９７において、管軸方向の最大輝度およびスリット光の照射領域から外れる地合部領域の最大輝度をそれぞれ求め、管軸方向の最大輝度と地合部領域の最大輝度を予め定めた比で内分して得られる輝度を閾値とし、その閾値より大である輝度およびそれを示す管軸方向座標の加重平均を当該幅方向座標における管軸方向の擬似断面座標とし、擬似断面座標を幅方向に連ねて得られる擬似断面形状と、スリット光の光源、撮像手段および電縫溶接管の幾何学的位置関係から決まる所定の変換式に基づいて電縫溶接管のビード切削形状を算出する方法およびその装置を提案した。
【００１７】
これによれば、電縫溶接管のビード切削形状を、光切断像の切削部と非切削部における輝度レベルの違いの影響を受けることなく精度よく計測することが可能となった。しかしながら、発明者らのその後の検討によると、測定時に採取される光切断画像中の光切断像の輝度が極端に低下し、それを外れた領域（地合部）の輝度と同程度になるなど極めてＳＮ比が低くなった場合には、光切断線の位置として算出する結果がノイズの影響で正しい位置から外れてしまい、溶接ビード切削形状の計測結果の表示が著しくゆがんでしまう問題があることが判明し、この点に若干の改善の余地があった。
【００１８】
このような光切断法におけるノイズの影響の抑止に関しては、従来、光切断法を用いる他の技術分野での提案が知られている。
【００１９】
すなわち、特開昭５７−２０８４０４号公報では、光切断像の上から下に縦方向に検索していって所定の設定値より大きな部分が最初に発生した区間内のみから光切断線を抽出し、以降その１本の走査線での光切断線の抽出を中止することにより、対象物上のスリット輝線位置以外の異常反射部を光切断線の一部として誤検出することを防止する方法を提案している。
【００２０】
また、特開平２−３５３０６号公報では、採取した光切断画像を、光切断線を横切る方向に全域を走査し、その走査線上にノイズ画像によるピーク値を持つ場合には全画面の同一走査線上で検出された光切断線位置を基準として光切断探索範囲を設定しノイズ画像を無視する形状検出方法が提案されている。
【００２１】
また、特開平４−２４０５０８号公報においては、光切断像に基づいて測定対象物の座標を算出し、その像の形状が周囲の像と離れて存在する針状である場合には虚像と判定し、そのデータを無視して形状認識することを特徴とする三次元形状認識装置を提案している。
【００２２】
しかしながら、特開昭５７−２０８４０４号公報に開示された方法においては、唯一の光切断抽出区間を識別するのに固定の閾値Ｖ１を用いているために、採取画像中の光切断線の輝度が切削部・非切削部間で大きく変動する切削ビード形状の計測には適用不可能であるのはすでに説明したとおりである。
【００２３】
また、特開平２−３５３０６号公報に開示された方法は、電子部品のはんだ付け部のように、長手方向に該均一なサイズをもつ凸形状をした部品がスリット光方向に等間隔に並んでいることが前提となっており、ノイズの発生は隣の部品からのスリット光の反射による２次光と説明されており、電縫管の切削部で同様のノイズ発生状況が生成されることはないので、本発明の課題に適用不可であるのは明らかである。
【００２４】
また、特開平４−２４０５０８号に開示された技術では、切削段差が発生した切削ビードの光切断像は段差部分で光切断像が不連続になるといった状況下において、この段差部分を不連続像（虚像）と誤認識して無視してしまい、結果として切削不良の見逃しにつながる恐れがある、といった問題点があった。
【００２５】
つまり、本発明の属する技術分野においても、またその他の技術分野における光切断法による形状認識技術の分野においても、光切断線の像と周囲とのＳＮが低下した場合であっても溶接ビード切削形状を正確に計測する方法は未だ見出されていない。
【００２６】
本発明は上記のような問題を解決するべくなされたもので、光切断法による立体形状測定においてＳＮ比の低下に起因する画像処理異常部位を切削により生ずる段差部と容易に識別可能とする計測方法および計測装置を提供することを目的とする。
【００２７】
【課題を解決するための手段】
請求項１の発明は、電縫溶接管の溶接部に生成された管内面あるいは外面のビード位置に照射したスリット光の像である光切断像を前記スリット光の照射方向と異なる角度から撮像手段により撮像して得られる光切断画像に所定の画像処理を施すことにより該電縫溶接管のビード形状を算出する電縫管の溶接ビード切削形状計測方法において、該光切断像と該光切断像を所定の画像処理手段により細線化後の光切断像とを重ね合わせた画像を表示するようにしたことを特徴とする、電縫溶接管の溶接ビード切削形状計測方法である。
【００２８】
請求項２の発明は、請求項１の発明において、細線化後の光切断像の各画素の色を、該画素に対応する光切断画像上の光切断像の輝度および該スリット光から外れた領域の最大輝度との比から定まるＳＮ比に応じた色で着色して表示するようにしたことを特徴とする、電縫溶接管の溶接ビード形状計測方法である。
【００２９】
請求項３の発明は、請求項１の発明において、照射したスリット光の像である光切断像を前記スリット光の照射方向と異なる角度から撮像手段により撮像して得られる光切断像に対して該光切断像を適切な画像処理手段により細線化後の光切断像の各画素の色を、該画素に対応する光切断画像上の光切断像の輝度および該スリット光から外れた領域の最大輝度との比から定まるＳＮ比に応じた色で分類して着色し、前記光切断像と重ね合わせて画像表示するようにしたことを特徴とする、電縫溶接管の溶接ビード形状計測方法である。
【００３０】
請求項４の発明は、切削後の電縫溶接管ビード部にスリット光をある入射角で照射するスリット光源と、前記スリット光の照射像を別な受光角で撮像する撮像手段と、前記撮像手段の出力する光切断画像に対して、スリット光の像を１本の画素で表示するように処理する細線化処理回路と、該光切断画像と前記細線化結果を同一画像上に重ね合わせる画像合成回路と、を備えたことを特徴とする、電縫溶接管の溶接ビード切削形状計測装置である。
【００３１】
請求項５の発明は、切削後の電縫溶接管ビード部にスリット光をある入射角で照射するスリット光源と、前記スリット光の照射像を別な受光角で撮像する撮像手段と、前記撮像手段の出力する光切断画像に対して、スリット光の像を１本の画素で表示するように処理する細線化処理回路と、前記細線化した光切断線の各画素の色を、該画素の対応する光切断画像上のスリット光画像の輝度と該スリット光からはずれた領域の最大輝度の比から定まるＳＮ比に応じて着色する細線変換回路と、備えたことを特徴とする、電縫溶接管の溶接ビード切削形状計測装置である。
【００３２】
請求項６の発明は、切削後の電縫溶接管ビード部にスリット光をある入射角で照射するスリット光源と、前記スリット光の照射像を別な受光角で撮像する撮像手段と、前記撮像手段の出力する光切断画像に対して、スリット光の像を１本の画素で表示するように処理する細線化処理回路と、前記細線化した光切断線の各画素の色を、該画素の対応する光切断画像上のスリット光画像の輝度と該スリット光からはずれた領域の最大輝度の比から定まるＳＮ比に応じて着色する細線変換回路と、前記光切断画像と前記細線変換回路が出力する彩色された細線化結果を同一画像上に重ね合わせる画像合成回路と、を備えたことを特徴とする、電縫溶接管の溶接ビード切削形状計測装置である。
【００３３】
【発明の実施の形態】
以下、図面を参照して本発明の実施の形態について説明する。
【００３４】
（実施例１）
図１は、電縫溶接管１０の内面ビードトリマー１２周辺を示したものであり、図１において、１４が切削バイト、１６が支持アーム、５０が本発明によるビード切削形状計測装置の測定ヘッド、７０が制御装置、９０が表示装置、そして９２が記録装置である。
【００３５】
測定ヘッド５０は、切削バイト１４の管搬送方向の下流側、好適には５００〜２０００ｍｍの位置に配置され、溶接シーム部からの輻射熱や溶接屑およびソリブル水の飛散から計測機器類を保護するための機構を備えていることが望ましく、また光学系の過熱や水、油、ヒューム等による汚損を防ぐため、洗浄と冷却をかねた気体パージ機構を備えることが望ましい。
【００３６】
また、制御装置７０、表示装置９０および記録装置９２は製造ラインから離れた作業位置、たとえば図示しないオペレータ操作盤付近に配置して、測定ヘッド５０とは支持アーム１６を経由するなどしてケーブル６０で接続されているが、その経路中で電気ノイズ等の混入を防ぐためにシールド構造となっていることが望ましい。
【００３７】
なお、以下の実施例の説明においては、管内面のビード切削形状の計測を行う構成になっているが、本発明による電縫溶接管のビード切削形状の計測方法および計測装置は管の外面であっても内面と同様に適用することができるのはもちろんである。
【００３８】
次に、測定ヘッド５０の構成を図２を用いて説明する。図２において、２０はスリット光源（以下、単に光源）、３０はカメラ、３２はレンズ、２４は光源電源、２５はカメラ電源、７２は画像データ変換回路である。
【００３９】
ここで、光源電源２４、カメラ電源２５、画像データ変換回路７２および以下で説明する演算回路群は制御装置７０として１つのケースに格納されるようにするのが望ましい。その演算回路群とは、細線化処理回路７５、画像合成回路８１である。
【００４０】
スリット光源２０は測定ヘッド５０内にあって電縫溶接管１０の断面と角度αをなし、管周方向（幅方向）に所定の照射幅をもち、管軸方向にはできるだけ細い、好適には０．０５ｍｍ以下の照射幅をもつ矩形状の照射像を形成するスリット光を照射するものであり、この点については、従来技術のものを踏襲する。
【００４１】
ここで、スリット光は半導体レーザー素子を発光部に利用したものが広く用いられ、また照射像を矩形状にするために、ナイフエッジを用いたスクリーンやシリンドリカルレンズなどを組み合わせたものが一般に市販されている。
【００４２】
また、この角度αは照射部への垂直な状態を０°としたとき９０°に近いほど後述のカメラで観察するビード切削形状が管軸方向に拡大されるが、同時に測定ヘッド５０と管内面との距離変動の影響も大きくなるので、本実施例では事前の実験により両者のバランスを考えα＝７０°を好適値として用いた。
【００４３】
カメラ３０はビード切削部に照射されたスリット光の照射像を電縫溶接管１０の断面と角度βをなす方向から観察するもので、従来より工業分野で広く用いられているＩＴＶやＣＣＤ、ＣＭＯＳ等の半導体撮像素子を用いたカメラを利用することができる。また、カメラの結像に用いるレンズ３２は市販のカメラ用レンズを用いればよいが、必要に応じ、背光等不要な光を光切断画像内から排除するために前記光源の波長にあわせた通過波長域を持つ帯域通過フィルタや、輻射熱によるカメラ撮像面やレンズの損傷を防止するための熱線カットフィルター等を有することが望ましい。
【００４４】
また、測定ヘッド５０は、内部のカメラあるいは光源、レンズ等の光学機器を熱や水等から保護するため、密閉構造にするのが好ましく、この場合、スリット光およびカメラ視野の部分のみにそれぞれ窓５２、５４を開けた構造にすることが好ましい。
【００４５】
カメラの配置角度は、（α＋β）が略９０°であることが望ましく、カメラの画素数および視野は、ビード部の幅および必要な分解能に基づいて決定すればよい。本発明では光源からのスリット光照射角度α＝７０°、撮像角度β＝３０°、視野の範囲を幅×高さ＝（２５ｍｍ×２０ｍｍ）、画素数は横×縦＝１３００×１０００画素を好適値として用いた。これにより、高さ方向の分解能は
２０／１０００＊ｃｏｓ（７０°）／ｓｉｎ（７０°＋３０°）＝０．００６９（ｍｍ）
また、幅方向の分解能は２５／１３００＝０．０１９２（ｍｍ）
となり、本実施例においては、幅方向（管周方向）２０μｍ、高さ方向（管軸方向）７μｍの分解能でビード切削形状を監視可能である。
【００４６】
また、光源２０とカメラ３０の光軸が丁度ビード切削部上で交差するように配置するのが適切であるのは言うまでもないが、さらに光源２０とカメラ３０の光軸が成す平面が電縫管の進行方向すなわち管の中心軸を含むように配置するのが一層望ましい。なぜならば、このように光源およびカメラを配置することにより、管内面の光切断像が光切断画像上のＹ軸方向に伸びる仮想中心線に対して左右対称に撮像できるからである。
【００４７】
更に、光源２０およびカメラ３０は図２のように傾けた状態で測定ヘッド５０に固定してもよいが、装置の小型化を図るために共に光軸が電縫管の中心軸と平行になるように配置して光軸を反射鏡３６で傾けるような構成にしてもよい。
【００４８】
次に制御装置７０の構成各部について説明する。画像データ変換回路７２は、カメラ３０が出力する画像信号を各画素毎の輝度データに変換して出力するもので、カメラ３０に対応した画像ボード（フレームグラバ）として近年広く市販されているものを利用すればよい。
【００４９】
細線化処理回路７５は、採取した画像中のスリット光の像の細線化処理を行うもので、これは従来公知である細線化処理手段や、特願２００２−１２８４９７の細線化処理方法を用いればよい。
【００５０】
画像合成回路８１は、前記のようにして細線化処理したスリット光の画像と、画像データ変換回路が出力する元の光切断画像（原画像）を重ね合わせるものであり、具体的には、画像中の同一座標の画素同士において値の加算、論理和、あるいは原画像上に細線のみを上書きする、等の演算手段を行うものである。
【００５１】
次に、本実施例の動作について説明する。
【００５２】
図３は、電縫管１０製造時に本実施例の装置で観察された切削ビードの光切断画像であり、図４は図３の光切断像の細線化処理結果である。ここで、図４中の矢印で示すように、細線化結果に凹状のノッチが発生しているが、これは図４の○印の位置に散乱光ノイズがあったためである。これは、本実施例の出力が図５のようになることからわかる。本発明によれば、図５のように、元画像および細線化結果の両方を確認できるため、このような散乱光ノイズに起因するノッチを切削段差と誤認識することが回避できる。
【００５３】
（実施例２）
図６は、本発明の別な実施例にかかる制御装置７０内部の演算回路群の構成を示すブロック図である。本図に図示されていない、ビードトリマー１２およびそれに設置する測定ヘッド部５０は上述の第１の実施例と同一の構成でよいので省略する。
【００５４】
また、図６において、画像データ変換回路７２、細線化処理回路７５は、上述の実施例１と同一のものを用いればよい。
【００５５】
ＳＮ比検出回路７７は、細線化処理を行う際の画像中の同一Ｘ座標における、光切断線の像の輝度と光切断線から外れた部分の輝度の比を各Ｘ座標毎に算出するものであり、既知の最大値探索回路と除算回路の組み合わせで実現できる。
【００５６】
また、細線変換回路８８は、細線化像の細線部分の画素の色を、ＳＮ比演算回路が出力する各Ｘ座標のＳＮ比に応じて着色するものであり、グレースケールあるいは任意の色配列で着色すればよい。本実施例での好適例では、表１のようにＳＮ比に応じた色を１６段階で割り当てるようにした。表１に関しては、通例知られている色呼称の中間色を多用することになるので、Ｒ，Ｂ，Ｇそれぞれの輝度による標記と併記した。
【００５７】
【表１】

【００５８】
次に、本実施例の実施結果について説明する。
【００５９】
図７は、電縫管１０製造時に本実施例の装置で観察された切削ビードの光切断画像であり、図８は図９の光切断像の細線化処理結果である。ここで、図８中の矢印で示す部分は細線化結果に大きな突起状の部分が発生しているが、これはこの部分のスリット光の輝度がとても小さいため細線化処理に際し異常になったのが原因であるが、従来の線だけの表示ではそれを識別することはできない。それに対し、図９に示すのが本実施例の細線変換回路の出力する細線化像であり、図８の○印に相当する部分はＳＮが最低レベル（青色、あるいは青緑）であることが細線化像の色から判断できるので、この部分の切削形状を誤認識するのを防止できた。
【００６０】
（実施例３）
図１０は、本発明の更に別な実施例にかかる制御装置７０内部の演算回路群の構成を示すブロック図である。本図に図示されていない、ビードトリマー１２およびそれに設置する測定ヘッド部５０は上述の実施例１と同一の構成でよいので省略する。
【００６１】
また、図１０において、画像データ変換回路７２、細線化処理回路７５は、上述の実施例１と同一のものを、ＳＮ比検出回路７７、細線変換回路８８は、上述の実施例２と同一のものを用いればよい。
【００６２】
次に、本実施例の実施結果について説明する。
【００６３】
図１１は、電縫管１０製造時に本実施例の装置で観察された切削ビードの光切断画像であり、図１２は図１１の光切断画像中に示される光切断像の細線化処理結果である。ここで、図１２中の矢印で示す部分は細線化結果に凹凸状の形状が発生しているが、これはこの部分のスリット光の輝度がとても小さいことに加え、散乱ノイズの影響が出たことが重なり、細線化処理に際し、異常になったのが原因であるが、従来の線だけの表示ではそれを識別することはできない。それに対し、図１３に示すのが本実施例の細線変換回路の出力する細線化像であり、図１２の○印に相当する部分はＳＮが最低レベル（青色、あるいは青緑）でありかつ元の光切断線の像から外れていることが明確に判別できるので、この部分の切削段差との誤認識を防止することができた。
【００６４】
以上説明した実施例においては、光切断線に着色する色の好適例の標記法としてコンピューターグラフィックスの分野で最も一般的なＲＢＧ系統で説明したが、本発明はこれに限るものではなく、ＣＹＭＫなど他の色標記法によっても同様の効果が得られるのは明らかである。
【００６５】
又、以上説明した実施例においては、制御装置７０内の細線化処理回路７２、ＳＮ比検出回路７７その他の画像処理演算回路群の一部あるいは全部は、ディジタルコンピュータ内のソフトウェアあるいはＲＯＭ化プログラム等により実現しても勿論よい。
【００６６】
【発明の効果】
本発明により、光切断法による立体形状算出結果中の段差部と画像処理異常値を識別できるようにしたので、スリット光のＳ／Ｎがある程度低くなった場合でも切削部と非切削部における輝度レベルの違いの影響を受けることなく精度よく計測することができる。また、ビード切削形状データを自動的に演算、記録して定量的な判定や傾向把握、さらには切削位置制御と組み合わせる場合でも、本技術により光切断処理の異常状態を加味して記録することにより、データの信頼性を向上させることが可能であるので、単に光切断画像を目視監視するだけでなく、高度な電縫溶接管製造操業が可能となる。
【図面の簡単な説明】
【図１】本発明にかかる電縫溶接管のビード切削形状計測装置を備えた内面ビードトリマーを示した概略図
【図２】本発明にかかるビード切削形状計測装置の要部の構成を示すブロック図
【図３】本発明の実施例１にかかる電縫管のビード切削部の光切断画像計測例を示す図
【図４】同じく電縫管のビード切削部の光切断画像を細線化処理した画像例を示す図
【図５】同じく画像合成回路が出力する画像例を示す図
【図６】本発明の実施例２にかかるビード切削形状計測装置の要部の構成を示すブロック図
【図７】同じく電縫管のビード切削部の光切断画像計測例を示す図
【図８】同じく電縫管のビード切削部の光切断画像を細線化処理した画像例を示す図
【図９】同じく細線変換回路が出力する画像例を示す図
【図１０】本発明の実施例３にかかるビード切削形状計測装置の要部の構成を示すブロック図
【図１１】同じく電縫管のビード切削部の光切断画像計測例を示す図
【図１２】同じく電縫管のビード切削部の光切断画像を細線化処理した画像例を示す図
【図１３】同じく画像合成回路が出力する画像例を示す図
【図１４】光切断法の原理を説明する概略図
【図１５】光切断法により電縫溶接管のビード切削部を計測した場合に、光切断画像の一部の輝度が著しく低下している例を示す図
【図１６】同じく、切削部の輝度を高めた場合に、非切削部にハレーションが発生している例を示す図
【符号の説明】
１０…電縫溶接管
１２…ビードトリマー
１４…切削バイト
１６…支持アーム
２０…光源
２４…光源電源
２５…カメラ電源
３０…カメラ
３２…レンズ
５０…測定ヘッド
５２，５４…窓
７０…制御装置
７２…画像データ変換回路
７５…細線化処理回路
７７…ＳＮ比検出回路
８１…画像合成回路
８８…細線変換回路
９０…表示装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and a device for measuring a weld bead cutting shape of an ERW pipe.
[0002]
[Prior art]
In general, an ERW pipe (hereinafter, referred to as an "ERW pipe" in the text for short), such as an ERW pipe, is formed by transporting a steel strip (including a steel plate) while shaping it into a tubular shape. It is manufactured by continuously butt-welding the width ends of the strip in the longitudinal direction of the steel strip by means such as high-frequency induction heating pressure welding or resistance heating pressure welding.
[0003]
In the welded portion of the ERW pipe, a bulge due to pressure welding, that is, a bead is formed on the inner and outer surfaces of the pipe. Usually, this bead is continuously formed in the longitudinal direction of the steel strip by a cutting tool installed downstream of the welding machine in the production line. Is cut into It is desirable that the shape of the bead portion after cutting and removal (hereinafter referred to as bead cutting shape) is ideally integrated with the contour shape of the steel strip base material portion so that it is difficult to know where the bead portion was. It is necessary to hold the tip of the cutting tool at an appropriate position on the surface of the ERW tube in order to approach the position.
[0004]
For this reason, conventionally, at the start of cutting, an operator performs visual judgment, measures the thickness of the cut portion with a micrometer or the like, and adjusts the cutting bite to an optimum position. During the manufacture of the pipe, cutting defects such as residual bead cutting or deep cutting may occur on the product ERW pipe due to misalignment of the cutting bit or chipping of the cutting bit for various reasons.
[0005]
Such poor cutting not only impairs the appearance of the product ERW pipe, but when a pipe having such a poorly cut part is applied to a pressurized pipe such as a gas line, in the worst case, there is a risk of pipe rupture. .
[0006]
Therefore, it is necessary to measure and monitor the bead cutting shape during the manufacture of the pipe, and to appropriately correct the cutting bit position according to the result.
[0007]
However, monitoring of the bead cutting shape has to rely on the visual observation of the operator, even on the outer surface of the tube which is easy to observe from the outside.Therefore, there is a question about quantitativeness and reliability, such as lack of accuracy and reproducibility. .
[0008]
With regard to the inner surface of the pipe, the bead part cannot be directly observed during manufacturing due to the configuration of the line, and the end of the pipe is observed when the pipe is cut at the final position of the line, or the operation is interrupted and the bead position of the pipe is stopped. Is sampled by gas fusing and sampling, and observing the inner surface.However, in the former method, since the observation position is several tens meters or more downstream from the cutting position, there is no abnormality in cutting. Even if it occurs, there is a problem that the length of the defective portion generated until this is detected becomes long, and the yield decreases. Further, in the latter, there is a problem such as seizure due to frictional heat if the cutting tool is not released with the stop of the line, so that even if the operation of the line is restarted, a step is formed in the bead cutting shape, and the yield decreases. Above, there was a problem that the line had to be stopped, and the production efficiency decreased. In addition, since both of them only inspect a part in the tube axis direction, there is a problem that the quality control system for guaranteeing the quality of the entire product cannot be met.
[0009]
In order to solve these problems, a method using a light cutting method has been conventionally proposed as a semi-automatic bead cutting shape measuring method. Here, the light cutting method is disclosed in, for example, JP-A-57-108705. As shown in FIG. 14, a light source 1 slits light from an electric resistance welded steel pipe (also referred to simply as an electric resistance welded pipe) 100 as an object to be measured. 2 and the camera 3 observes from an angle β different from the incident angle α, a slit image (light cut image) deformed according to the surface shape of the object to be measured is observed, and this light cut image and the observation optical system are observed. This is for calculating the shape of the object (for example, the beat portion 11) from the geometrical arrangement, and has advantages such as a simple observation optical system and a wide range of measurement sensitivity depending on the geometric arrangement of the observation optical system. There is. By the way, the area outside the slit light irradiation area is referred to as the formation section.
[0010]
Further, for example, in the technique disclosed in Japanese Patent Application Laid-Open No. 52-96049, a bead shape observing method for observing a weld bead portion that is not cut by a light cutting method and providing a scale on a display monitor in accordance with an enlargement ratio determined by an optical arrangement. Has been proposed.
[0011]
However, all of these methods are only for displaying a measurement image (light cutting image), and the determination of the bead cutting shape is performed by an operator visually judging a monitor, and has not yet reached automatic measurement.
[0012]
In this regard, as a quantification method for automatic measurement, for example, there is a technique disclosed in Japanese Patent No. 2618303. According to this, when measuring the shape of an ERW pipe after welding bead cutting, an image of a steel pipe bead cutting portion is captured using slit light and a light cutting image by an ITV camera, and the cross-sectional shape image (light cutting image) is thinned. The cross-sectional shape is calculated by processing (viewing the area where one pixel is connected in one direction as a thin line), and the brightness of the cross-sectional shape is used to distinguish between the base material that is the cut portion and the non-cut portion, and the distinction is made. A method has been proposed in which the median value of the cutting portion, the value at the right end of the cutting portion, and the value at the left end of the cutting portion are obtained, and the cutting depth amount and the cutting inclination amount are calculated based on these three measured values.
[0013]
[Problems to be solved by the invention]
However, in the technique disclosed in Japanese Patent No. 2618303, as a specific method of the thinning processing, the maximum luminance in the direction parallel to the tube axis (Y-axis direction) obtained from the light-section image is set in the tube circumferential direction (material). In the case of a steel plate or a steel strip, it corresponds to the width direction of the steel plate and is hereinafter referred to as the width direction). Therefore, there is a problem that an accurate cross-sectional shape may not be obtained.
[0014]
This will be described in detail, but according to the experience of the inventors repeating experiments at the manufacturing site, the surface of the same part of the ERW pipe immediately after cutting is in a mirror state, while the surrounding non-cut part is oxidized. Since the film or the like is attached and is dark, the degree of irregular reflection of the slit light is different. For this reason, the brightness of the light cut image of the bead cutting portion is not always the same in the width direction. For example, as shown in FIG. 15, the slit light of the cut portion is almost specularly reflected (reflected in the direction opposite to the incident direction at the same angle as the incident angle), and the luminance thereof is 1/10 or less of the non-cut portion. It may be. This is because if the incident angle and the light receiving angle are different, such specularly reflected light looks rather low in brightness.
[0015]
In such a case, the light cut image is buried in noise, and a bead cut shape cannot be obtained well. If the brightness of the cutting part is to be increased by increasing the gain of the observation optical system such as an ITV camera or lengthening the exposure time, the non-cutting part will be changed to the observation optics of the aforementioned camera as shown in the right part of FIG. The range over (halation) exceeding the maximum luminance in the specifications of the system occurs, and the shape of the non-cut portion cannot be accurately determined. The reason is that when such a luminance overrange occurs, a plurality of tube axis direction coordinates (Y axis coordinates) indicating the maximum luminance appear in the non-cut portion in the light-section image, and the tube axis direction indicating the maximum luminance. This is because the coordinates (Y-axis coordinates) cannot be uniquely determined.
[0016]
In order to solve such a problem, the inventors have previously determined in Japanese Patent Application No. 2002-128497 the maximum luminance in the tube axis direction and the maximum luminance in the formation region that deviates from the slit light irradiation region. The luminance obtained by internally dividing the maximum luminance in the axial direction and the maximum luminance in the formation region at a predetermined ratio is used as a threshold, and the luminance greater than the threshold and the weighted average of the tube axis direction coordinates indicating the luminance are used as the threshold. A pseudo cross-sectional coordinate in the tube axis direction in the width direction coordinate, a predetermined cross-sectional shape obtained by connecting the pseudo cross-sectional coordinate in the width direction, and a geometrical positional relationship between the light source of the slit light, the imaging means, and the ERW pipe. A method and a device for calculating the bead cutting shape of an ERW pipe based on the above conversion formula have been proposed.
[0017]
According to this, the bead cutting shape of the ERW pipe can be accurately measured without being affected by the difference in luminance level between the cut portion and the non-cut portion of the light-cut image. However, according to a subsequent study by the inventors, the brightness of the light-section image in the light-section image collected at the time of measurement is extremely reduced, and is substantially the same as the brightness of a region (formation portion) outside the light-section image. For example, when the SN ratio is extremely low, the result calculated as the position of the light cutting line deviates from the correct position due to the influence of noise, and the display of the measurement result of the weld bead cutting shape is significantly distorted. It turned out that there was some room for improvement in this regard.
[0018]
Regarding the suppression of the influence of noise in such a light-section method, proposals in other technical fields using the light-section method have been conventionally known.
[0019]
That is, in Japanese Patent Application Laid-Open No. 57-208404, a light-section image is extracted vertically only from within a section in which a portion larger than a predetermined set value is first searched vertically from above to below. A method for preventing the abnormal reflection part other than the slit bright line position on the object from being erroneously detected as a part of the light cutting line by stopping the extraction of the light cutting line in the one scanning line thereafter. is suggesting.
[0020]
In Japanese Patent Application Laid-Open No. Hei 2-35306, a sampled light-section image is scanned over the entire area in a direction crossing the light-section line, and when a noise image has a peak value on the scanning line, the entire image is scanned on the same scanning line. There has been proposed a shape detection method in which a light-section search range is set based on the position of the light-section line detected by the method described above, and a noise image is ignored.
[0021]
In Japanese Patent Laid-Open No. Hei 4-240508, the coordinates of an object to be measured are calculated based on a light-section image, and if the shape of the image is a needle-like shape that is separated from a surrounding image, it is determined to be a virtual image. In addition, a three-dimensional shape recognizing device characterized by recognizing a shape ignoring the data has been proposed.
[0022]
However, in the method disclosed in Japanese Patent Application Laid-Open No. 57-208404, since the fixed threshold V1 is used to identify the only light-section extraction section, the brightness of the light-section line in the sampled image is low. As described above, it is not applicable to the measurement of the cutting bead shape that fluctuates greatly between the cutting portion and the non-cutting portion.
[0023]
Further, the method disclosed in Japanese Patent Application Laid-Open No. 2-35306 discloses a method in which convex parts having a uniform size in the longitudinal direction, such as soldered parts of electronic parts, are arranged at equal intervals in the slit light direction. It is assumed that the noise generation is secondary light due to the reflection of slit light from the adjacent part, and the same noise generation situation is generated at the cutting part of the ERW pipe. Clearly, it is not applicable to the subject of the present invention.
[0024]
Further, according to the technique disclosed in Japanese Patent Application Laid-Open No. 4-240508, a light cut image of a cutting bead in which a cutting step occurs has a discontinuous image at a step portion. (Virtual image) is erroneously recognized and ignored, and as a result, there is a possibility that a cutting defect may be overlooked.
[0025]
In other words, in the technical field to which the present invention belongs, and in the field of shape recognition technology using the light cutting method in other technical fields, even if the SN between the image of the light cutting line and the surroundings is reduced, welding bead cutting is performed. A method for accurately measuring the shape has not been found yet.
[0026]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and is a measurement that can easily identify an image processing abnormal portion due to a decrease in an SN ratio from a step portion caused by cutting in a three-dimensional shape measurement by a light cutting method. It is an object to provide a method and a measuring device.
[0027]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided an imaging means for imaging a light section image, which is an image of a slit light applied to a bead position on an inner surface or an outer surface of a pipe generated at a weld portion of an electric resistance welded pipe, from an angle different from an irradiation direction of the slit light. In the method for measuring the weld bead cutting shape of the ERW pipe by calculating a bead shape of the ERW pipe by performing a predetermined image processing on the optical cutting image obtained by imaging, the light cutting image and the light cutting image A method for measuring a weld bead cutting shape of an electric resistance welded pipe, wherein an image obtained by superimposing a light-cut image after thinning by a predetermined image processing means is displayed.
[0028]
According to a second aspect of the present invention, in the first aspect of the present invention, the color of each pixel of the light section image after the thinning is deviated from the brightness of the light section image on the light section image corresponding to the pixel and the slit light. A method for measuring a weld bead shape of an ERW pipe, characterized in that the area is colored and displayed in a color corresponding to an SN ratio determined from a ratio with a maximum luminance of an area.
[0029]
According to a third aspect of the present invention, in the first aspect of the present invention, a light section image, which is an image of the illuminated slit light, is taken from an angle different from the irradiation direction of the slit light by an image pickup means. The color of each pixel of the light-section image after thinning the light-section image by an appropriate image processing means is set to the maximum of the brightness of the light-section image on the light-section image corresponding to the pixel and the area deviating from the slit light. A method for measuring a weld bead shape of an electric resistance welded pipe, characterized in that it is classified and colored by a color corresponding to an SN ratio determined from a ratio with luminance and is superimposed on the light-section image and displayed as an image. is there.
[0030]
The invention according to claim 4 is characterized in that a slit light source for irradiating a bead portion of the ERW weld pipe after cutting with a slit light at a certain incident angle, an image pickup means for picking up an irradiation image of the slit light at a different light receiving angle, and A thinning processing circuit for processing the light section image output by the means so that an image of slit light is displayed by one pixel, and an image in which the light section image and the thinning result are superimposed on the same image A weld bead cutting shape measuring device for an electric resistance welded pipe, comprising: a synthesis circuit.
[0031]
The invention according to claim 5 is characterized in that a slit light source for irradiating the bead portion of the electric resistance welded pipe after cutting with a slit light at a certain incident angle, an image pickup means for picking up an irradiation image of the slit light at another light receiving angle, and A thinning processing circuit for processing the light cut image output by the means so that the image of the slit light is displayed by one pixel; and a color of each pixel of the thinned light cut line, ERW welding characterized by comprising: a thin line conversion circuit for coloring in accordance with the SN ratio determined from the ratio between the luminance of the slit light image on the corresponding light cut image and the maximum luminance of the area deviating from the slit light. This is a pipe weld bead cutting shape measuring device.
[0032]
The invention according to claim 6 is characterized in that a slit light source for irradiating a bead portion of the ERW pipe after cutting with a slit light at a certain incident angle, an imaging means for imaging an irradiation image of the slit light at a different light receiving angle, and A thinning processing circuit for processing the light cut image output by the means so that the image of the slit light is displayed by one pixel; and a color of each pixel of the thinned light cut line, A thin line conversion circuit for coloring in accordance with an SN ratio determined from a ratio between the brightness of the slit light image on the corresponding light cut image and the maximum brightness of an area deviating from the slit light, and the light cut image and the thin line conversion circuit output And an image synthesizing circuit that superimposes the colored thinning results on the same image.
[0033]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0034]
(Example 1)
FIG. 1 shows the periphery of an inner bead trimmer 12 of an electric resistance welded pipe 10. In FIG. 1, 14 is a cutting tool, 16 is a support arm, 50 is a measuring head of the bead cutting shape measuring device according to the present invention, 70 is a control device, 90 is a display device, and 92 is a recording device.
[0035]
The measuring head 50 is disposed on the downstream side of the cutting tool 14 in the pipe conveying direction, preferably at a position of 500 to 2000 mm, and in order to protect measuring instruments and the like from radiant heat from the welding seam portion and scattering of welding debris and solble water. In order to prevent overheating of the optical system and contamination by water, oil, fumes, etc., it is desirable to provide a gas purge mechanism that also performs cleaning and cooling.
[0036]
Further, the control device 70, the display device 90, and the recording device 92 are arranged at a work position away from the production line, for example, near an operator operation panel (not shown), and are connected to the measuring head 50 via the support arm 16 via the cable 60. However, it is desirable to have a shield structure in order to prevent electric noise and the like from being mixed in the path.
[0037]
In the following description of the embodiment, it is configured to measure the bead cutting shape of the inner surface of the pipe, but the method and the measuring device of the bead cutting shape of the ERW pipe according to the present invention are performed on the outer surface of the pipe. Of course, it can be applied similarly to the inner surface.
[0038]
Next, the configuration of the measuring head 50 will be described with reference to FIG. In FIG. 2, reference numeral 20 denotes a slit light source (hereinafter simply referred to as a light source), 30 denotes a camera, 32 denotes a lens, 24 denotes a light source power supply, 25 denotes a camera power supply, and 72 denotes an image data conversion circuit.
[0039]
Here, it is desirable that the light source power supply 24, the camera power supply 25, the image data conversion circuit 72, and the arithmetic circuit group described below are stored in one case as the control device 70. The arithmetic circuit group is a thinning processing circuit 75 and an image synthesis circuit 81.
[0040]
The slit light source 20 is located in the measuring head 50, forms an angle α with the cross section of the ERW pipe 10, has a predetermined irradiation width in the pipe circumferential direction (width direction), and is as narrow as possible in the pipe axis direction, preferably This is to irradiate slit light that forms a rectangular irradiation image having an irradiation width of 0.05 mm or less, and this point follows that of the prior art.
[0041]
Here, as the slit light, a light using a semiconductor laser element for a light emitting portion is widely used, and a light combining a screen using a knife edge or a cylindrical lens to form a rectangular irradiation image is generally commercially available. ing.
[0042]
When the angle α is closer to 90 ° when the state perpendicular to the irradiation unit is 0 °, the bead cutting shape observed by a camera described later is enlarged in the tube axis direction. In this embodiment, α = 70 ° was used as a suitable value in consideration of the balance between the two in a previous experiment, because the influence of the distance variation from the distance becomes large.
[0043]
The camera 30 observes an irradiation image of the slit light applied to the bead cutting portion from a direction forming an angle β with the cross section of the electric resistance welded pipe 10, and has conventionally used ITV, CCD, and CMOS widely used in the industrial field. A camera using a semiconductor imaging device such as described above can be used. A commercially available camera lens may be used as the lens 32 used for image formation of the camera. If necessary, a passing wavelength adjusted to the wavelength of the light source is used to exclude unnecessary light such as backlight from the light cut image. It is desirable to have a bandpass filter having a band, a heat ray cut filter for preventing damage to the camera imaging surface and the lens due to radiant heat, and the like.
[0044]
The measuring head 50 preferably has a hermetically sealed structure in order to protect the internal camera or optical devices such as a light source and a lens from heat, water, and the like. In this case, windows are provided only in the slit light and the camera field of view. It is preferable to have a structure in which 52 and 54 are opened.
[0045]
It is desirable that the arrangement angle of the camera is (α + β) approximately 90 °, and the number of pixels and the field of view of the camera may be determined based on the width of the bead portion and the required resolution. In the present invention, the slit light irradiation angle α = 70 ° from the light source, the imaging angle β = 30 °, the range of the visual field is width × height = (25 mm × 20 mm), and the number of pixels is preferably horizontal × vertical = 1300 × 1000 pixels. Used as value. As a result, the resolution in the height direction is
20/1000 * cos (70 °) / sin (70 ° + 30 °) = 0.0069 (mm)
The resolution in the width direction is 25/1300 = 0.0192 (mm)
In this embodiment, the bead cutting shape can be monitored with a resolution of 20 μm in the width direction (pipe circumferential direction) and 7 μm in the height direction (pipe axis direction).
[0046]
It is needless to say that it is appropriate to arrange the light source 20 and the optical axis of the camera 30 so as to intersect exactly on the bead cutting portion. It is more desirable to arrange so as to include the traveling direction of the tube, that is, the central axis of the tube. This is because, by arranging the light source and the camera in this way, the light section image of the inner surface of the tube can be taken symmetrically with respect to the virtual center line extending in the Y-axis direction on the light section image.
[0047]
Further, the light source 20 and the camera 30 may be fixed to the measuring head 50 in an inclined state as shown in FIG. 2, but in order to reduce the size of the apparatus, both optical axes are parallel to the central axis of the ERW tube. And the optical axis may be inclined by the reflecting mirror 36.
[0048]
Next, each component of the control device 70 will be described. The image data conversion circuit 72 converts an image signal output from the camera 30 into luminance data for each pixel and outputs the converted signal. A commercially available image board (frame grabber) corresponding to the camera 30 is widely used in recent years. Just use it.
[0049]
The thinning processing circuit 75 performs thinning processing of the image of the slit light in the collected image. Good.
[0050]
The image synthesizing circuit 81 superimposes the image of the slit light subjected to the thinning processing as described above and the original light section image (original image) output from the image data conversion circuit. Calculation means for adding values, logical sums, or overwriting only fine lines on the original image between pixels having the same coordinates in the middle are performed.
[0051]
Next, the operation of the present embodiment will be described.
[0052]
FIG. 3 is an optical cut image of the cutting bead observed by the apparatus of the present embodiment at the time of manufacturing the electric resistance welded pipe 10, and FIG. 4 is a result of the thinning processing of the optical cut image of FIG. Here, as shown by the arrow in FIG. 4, a concave notch is generated in the thinning result, which is due to the presence of scattered light noise at the position indicated by the circle in FIG. This can be seen from the output of this embodiment as shown in FIG. According to the present invention, as shown in FIG. 5, since both the original image and the thinning result can be confirmed, it is possible to avoid erroneously recognizing a notch caused by such scattered light noise as a cutting step.
[0053]
(Example 2)
FIG. 6 is a block diagram showing a configuration of an arithmetic circuit group inside a control device 70 according to another embodiment of the present invention. A bead trimmer 12 and a measuring head unit 50 installed on the bead trimmer, which are not shown in the drawing, may have the same configuration as that of the above-described first embodiment, and thus a description thereof will be omitted.
[0054]
6, the same image data conversion circuit 72 and thinning processing circuit 75 as those in the first embodiment may be used.
[0055]
The SN ratio detection circuit 77 calculates, for each X coordinate, the ratio between the luminance of the image of the light section line and the luminance of a portion deviating from the light section line at the same X coordinate in the image when performing the thinning processing. And can be realized by a combination of a known maximum value search circuit and a division circuit.
[0056]
Further, the thin line conversion circuit 88 is for coloring the color of the pixel in the thin line portion of the thin line image according to the SN ratio of each X coordinate output from the SN ratio calculation circuit, and is in gray scale or an arbitrary color array. What is necessary is just to color. In the preferred example of this embodiment, colors according to the SN ratio are assigned in 16 levels as shown in Table 1. In Table 1, since intermediate colors of commonly known color designations are frequently used, they are described together with the notation based on the luminance of each of R, B, and G.
[0057]
[Table 1]

[0058]
Next, the results of the embodiment will be described.
[0059]
FIG. 7 is an optical cut image of the cutting bead observed by the apparatus of the present embodiment at the time of manufacturing the electric resistance welded pipe 10, and FIG. 8 is a result of the thinning processing of the optical cut image of FIG. Here, the portion indicated by the arrow in FIG. 8 has a large protruding portion in the thinning result, which is abnormal during the thinning process because the brightness of the slit light in this portion is very small. However, it cannot be identified by the conventional line-only display. On the other hand, FIG. 9 shows a thinned image output from the thin line conversion circuit of the present embodiment, and the portion corresponding to the circle in FIG. 8 may have the lowest SN (blue or blue-green). Since it can be determined from the color of the thinned image, it is possible to prevent the cut shape of this portion from being erroneously recognized.
[0060]
(Example 3)
FIG. 10 is a block diagram showing a configuration of an arithmetic circuit group inside a control device 70 according to still another embodiment of the present invention. A bead trimmer 12 and a measuring head unit 50 installed on the bead trimmer, which are not shown in FIG.
[0061]
In FIG. 10, the image data conversion circuit 72 and the thinning processing circuit 75 are the same as those in the first embodiment, and the SN ratio detection circuit 77 and the thin line conversion circuit 88 are the same as those in the second embodiment. What should be used.
[0062]
Next, the results of the embodiment will be described.
[0063]
FIG. 11 is an optical cut image of a cutting bead observed by the apparatus of the present embodiment at the time of manufacturing the electric resistance welded pipe 10, and FIG. 12 is a thinning processing result of the optical cut image shown in the optical cut image of FIG. is there. Here, the portion indicated by the arrow in FIG. 12 has an uneven shape as a result of the thinning, which is due to the fact that the brightness of the slit light in this portion is very low and the influence of scattering noise has appeared. This is due to the fact that an abnormality has occurred during the thinning process, but it cannot be identified by the conventional display of only the lines. On the other hand, FIG. 13 shows a thinned image output from the thin line conversion circuit according to the present embodiment, and a portion corresponding to a circle in FIG. 12 has the lowest SN (blue or blue-green) and the original value. Can be clearly determined to be out of the image of the light cutting line, so that erroneous recognition of this portion as a cutting step can be prevented.
[0064]
In the embodiments described above, the most common RBG system in the field of computer graphics has been described as a preferred example of the coloration method for coloring the light cutting line. However, the present invention is not limited to this. It is clear that similar effects can be obtained by other color notation methods.
[0065]
In the above-described embodiment, part or all of the thinning processing circuit 72, the SN ratio detection circuit 77, and other image processing operation circuits in the control device 70 are implemented by software or a ROM program in a digital computer. Of course, it may be realized by.
[0066]
【The invention's effect】
According to the present invention, it is possible to distinguish between a step portion and an abnormal value in image processing in the calculation result of the three-dimensional shape by the light cutting method. Therefore, even if the S / N of the slit light is reduced to some extent, the brightness in the cut portion and the non-cut portion is reduced Measurement can be performed accurately without being affected by the difference in level. In addition, even when bead cutting shape data is automatically calculated and recorded to quantitatively judge and grasp trends, and even when combined with cutting position control, this technology takes into account the abnormal state of light cutting processing and records it. Since it is possible to improve the reliability of the data, it is possible to not only monitor the light-cut image visually, but also to perform an advanced operation of electric resistance welded pipe manufacturing.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an internal bead trimmer equipped with a bead cutting shape measuring device for an ERW pipe according to the present invention.
FIG. 2 is a block diagram showing a configuration of a main part of the bead cutting shape measuring device according to the present invention.
FIG. 3 is a diagram showing an example of a light-cut image measurement of a bead cut portion of the ERW pipe according to the first embodiment of the present invention.
FIG. 4 is a diagram showing an example of an image obtained by thinning a light-cut image of a bead cut portion of an electric resistance welded tube.
FIG. 5 is a diagram showing an example of an image output from the image synthesizing circuit.
FIG. 6 is a block diagram showing a configuration of a main part of a bead cutting shape measuring apparatus according to a second embodiment of the present invention.
FIG. 7 is a diagram showing an example of measuring an optically cut image of a bead cut portion of an ERW pipe.
FIG. 8 is a diagram showing an example of an image obtained by thinning a light-cut image of a bead cut portion of an electric resistance welded tube.
FIG. 9 is a diagram showing an example of an image output from the thin line conversion circuit.
FIG. 10 is a block diagram showing a configuration of a main part of a bead cutting shape measuring apparatus according to a third embodiment of the present invention.
FIG. 11 is a view showing an example of measuring an optically cut image of a bead cut portion of an ERW pipe.
FIG. 12 is a diagram showing an example of an image obtained by thinning a light-cut image of a bead cutting portion of an ERW pipe.
FIG. 13 is a diagram showing an example of an image output from the image synthesizing circuit.
FIG. 14 is a schematic diagram illustrating the principle of the light-section method.
FIG. 15 is a view showing an example in which the brightness of a part of the light-cut image is significantly reduced when the bead cut portion of the ERW pipe is measured by the light-cut method.
FIG. 16 is a diagram showing an example in which halation occurs in a non-cut portion when the brightness of the cut portion is increased.
[Explanation of symbols]
10. ERW welded pipe
12: Bead trimmer
14 ... Cutting tool
16 ... Support arm
20 ... light source
24 ... Light source power supply
25 ... Camera power supply
30 ... Camera
32 ... Lens
50 ... Measuring head
52, 54 ... windows
70 ... Control device
72 ... Image data conversion circuit
75 ... Thinning processing circuit
77 ... SN ratio detection circuit
81 ... Image synthesis circuit
88: Fine wire conversion circuit
90 ... Display device

Claims

Light obtained by imaging an optical cutting image, which is an image of a slit light applied to a bead position on an inner surface or an outer surface of a pipe generated at a weld portion of an ERW pipe, from an angle different from the irradiation direction of the slit light by an imaging unit. In the method for measuring the weld bead cutting shape of the ERW pipe, which calculates a bead shape of the ERW pipe by performing predetermined image processing on the cut image,
A weld bead cutting shape for an electric resistance welded pipe, wherein an image obtained by superimposing the light cut image and the light cut image after thinning the light cut image by a predetermined image processing means is displayed. Measurement method.

In Claim 1, the color of each pixel of the light-section image after thinning is determined from the ratio of the luminance of the light-section image on the light-section image corresponding to the pixel and the maximum luminance of a region outside the slit light. A method for measuring the shape of a weld bead of an ERW pipe, characterized in that the color is displayed in a color corresponding to the SN ratio.

2. The image processing apparatus according to claim 1, wherein the light-cut image obtained by imaging the light-cut image, which is an image of the irradiated slit light, from an angle different from the irradiation direction of the slit light by an image pickup means is subjected to predetermined image processing. The color of each pixel of the light-section image after the thinning by means is converted into an SN ratio determined from the ratio of the luminance of the light-section image on the light-section image corresponding to the pixel and the maximum luminance of the region deviating from the slit light. A method for measuring the shape of a weld bead of an electric resistance welded pipe, wherein the color is classified and colored according to an appropriate color, and the image is displayed by being superimposed on the light-section image.

A slit light source for irradiating a slit light at a certain incident angle to a bead portion of the ERW pipe after cutting,
Imaging means for imaging the irradiation image of the slit light at a different light receiving angle,
A thinning processing circuit for processing a light cut image output by the imaging means so that an image of slit light is displayed by one pixel;
An image synthesis circuit that superimposes the light section image and the thinning result on the same image,
A weld bead cutting shape measuring device for an electric resistance welded pipe, comprising:

A slit light source for irradiating a slit light at a certain incident angle to a bead portion of the ERW pipe after cutting,
Imaging means for imaging the irradiation image of the slit light at a different light receiving angle,
A thinning processing circuit for processing a light cut image output by the imaging means so that an image of slit light is displayed by one pixel;
The color of each pixel of the thinned light-section line is colored according to the SN ratio determined from the ratio of the luminance of the slit light image on the corresponding light-section image of the pixel to the maximum luminance of the area deviating from the slit light. A fine wire conversion circuit,
A weld bead cutting shape measuring device for an electric resistance welded pipe, comprising:

A slit light source for irradiating a slit light at a certain incident angle to a bead portion of the ERW pipe after cutting,
Imaging means for imaging the irradiation image of the slit light at a different light receiving angle,
A thinning processing circuit for processing a light cut image output by the imaging means so that an image of slit light is displayed by one pixel;
The color of each pixel of the thinned light-section line is colored according to the SN ratio determined from the ratio of the luminance of the slit light image on the corresponding light-section image of the pixel to the maximum luminance of the area deviating from the slit light. A fine wire conversion circuit,
An image synthesis circuit that superimposes the light-cut image and the colored thinning result output by the thin-line conversion circuit on the same image,
A weld bead cutting shape measuring device for an electric resistance welded pipe, comprising: