JP2004181462A

JP2004181462A - Welding system and method using residual stress evaluation

Info

Publication number: JP2004181462A
Application number: JP2002347875A
Authority: JP
Inventors: Naoteru Ogawa; 直輝小川; Itaru Muroya; 格室屋; Yoichi Iwamoto; 洋一岩本
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Ltd
Priority date: 2002-11-29
Filing date: 2002-11-29
Publication date: 2004-07-02

Abstract

<P>PROBLEM TO BE SOLVED: To analytically predict residual stress in the welding process of an actual structure and to control the welding of the structure in accordance with the result of the analytical prediction. <P>SOLUTION: In multi-layer welding through successive welding for the first through n-th (n is an integer 2 or above) welding path, an analytical model is formed corresponding to predetermined welding conditions on the first and the second member, with welding performed for the k-th (k is any integer 1 to (n-1)) welding pass in accordance with the welding conditions; in this welding process, the temperature of the first and the second member is measured to obtain the measured temperature. After completion of the welding for the k-th welding pass, residual stress is evaluated corresponding to the measured temperature using thermal elastoplasticity analysis relative to the analytical model, with an estimated residual stress obtained; and then, by making welding conditions variable in accordance with the estimated residual stress, variable welding conditions are set. Subsequently, with the welding conditions varied, welding is performed for the (k+1)th welding pass in accordance with the varied welding conditions. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明が属する技術分野】
本発明は、溶接によって生じる残留応力を解析評価して得られた評価結果を用いることにより、残留応力を低減して溶接を行うための溶接システム及び溶接方法に関するものである。
【０００２】
【従来の技術】
一般に、溶接構造物では、溶接によって残留応力及び残留変形が発生することがあり、このような残留応力等が所定の値を越えると、構造物に悪影響を及ぼす関係上、残留応力等は極力低減する必要がある。このため、従来、予め溶接構造物に発生するであろう残留応力を試験片等の解析対象物を用いて解析予測することが行われている。
【０００３】
例えば、解析対象物について有限要素法モデルを作成して、解析対象物表面の数点において残留応力を実測し、この実測残留応力に基づいて残留歪パターンを仮定する。そして、解析モデルについて、境界要素法を適用し、残留歪パターンに対する応力分布を求める。次に、残留応力の実測点の応力となる係数を決定した後、この係数を用いて解析対象物全体の応力分布を境界要素法によって求めている（特許文献１参照）。
【０００４】
さらに、構造物の任意の測定点で得られた残留変形量を強制変位データとして、構造物全体の表面に強制変位データを与えた後、構造物を構成する材料の機械的性質を示す関係式に応じて構造物全体の応力−歪関係を求めて、構造物全体の応力分布を予測することも行われている（特許文献２参照）。
【０００５】
また、有限要素法によって、切り込み法による残留応力の測定を詳細に模擬して、残留応力の実測値と有限要素法による解析値との比を補正係数として求めた後、この補正係数を、有限要素法で得られた残留応力分布に乗じて、応力分布を予測することが行われている（特許文献３参照）。
【０００６】
【特許文献１】
特開平５−２２３６６１号公報（段落（００３０）〜（００３９）、第１図）
【０００７】
【特許文献２】
特開平６−１８６１４１号公報（段落（０００８）〜（００１３）、第１図）
【０００８】
【特許文献３】
特開平１１−１４８８７５号公報（段落（００１６）〜（００２２）、第３図）
【０００９】
【発明が解決しようとする課題】
ところが、特許文献１〜３に記載された残留応力の解析予測手法では、試験片等の解析対象物に対して溶接を完了した後、解析対象物の残留応力を測定して、有限要素法等を用いて、解析対象物の応力分布を予測して、実際の構造物を溶接する際にこの解析結果を考慮するにすぎず、試験片等の解析対象物と実際の構造物とは同一ではないから、解析対象物について応力分布の解析予測を行っても、実際の構造物では応力分布が大きく異なることもあり、結果的に残留応力が所定の値を越えて、構造物に悪影響を及ぼすこともある。
【００１０】
さらに、特許文献１〜３に記載された残留応力の解析予測手法では、試験片等の解析対象物の残留応力を計測する関係上、解析対象物を切断したり、解析対象物に切り込みを入れなければならないことが多く、このような解析予測手法を実際の構造物の残留応力を解析予測する際に用いることはできない。
【００１１】
いずれにしても、特許文献１〜３に記載された残留応力の解析予測手法では、試験片等の解析対象物について残留応力を計測して、応力分布の解析予測をしているものの、実際の構造物の溶接工程において残留応力を解析予測することは難しいという課題がある。
【００１２】
そして、特許文献１〜３に記載された残留応力の解析予測手法を用いた際には、実際の構造物の溶接工程において残留応力を解析予測して、その解析予測結果を考慮して構造物の溶接を制御することはできない。
【００１３】
本発明の目的は、実際の構造物の溶接工程において残留応力を解析予測して、その解析予測結果に応じて構造物の溶接を制御することのできる溶接システム及び溶接方法を提供することにある。
【００１４】
【課題を解決するための手段】
本発明によれば、第１及び第２の部材を溶接によって接合して構造物とする際、前記第１及び前記第２の部材の当接部に規定される開先において第１〜第ｎ（ｎは２以上の整数）の溶接パスについて順次溶接を行って多層溶接を行うようにした溶接システムにおいて、前記第１及び前記第２の部材について予め設定された溶接条件に応じた解析モデルを生成する解析モデル生成手段と、前記予め定められた溶接条件に応じて第ｋ（ｋは１〜（ｎ−１）のいずれかの整数）の溶接パスについて溶接を行う過程で前記第１及び前記第２の部材の温度を計測して計測温度を得る温度計測手段と、前記第ｋの溶接パスについて溶接が終了した後、前記解析モデルについて熱弾塑性解析を用いて前記計測温度に応じて残留応力を評価して推定残留応力を得る残留応力評価手段と、前記推定残留応力に応じて前記予め設定された溶接条件を変更して変更溶接条件とする溶接条件変更手段とを有し、前記溶接条件変更手段によって前記予め設定された溶接条件が変更されると、第（ｋ＋１）の溶接パスについて前記変更溶接条件に応じて溶接を行うようにしたことを特徴とする残留応力評価を用いた溶接システムが得られる。
【００１５】
このようにして、第１及び第２の部材を溶接によって接合して構造物とする際、第１及び第２の部材について予め設定された溶接条件に応じた解析モデルを生成して、予め定められた溶接条件に応じて第ｋの溶接パスについて溶接を行う過程で、第１及び第２の部材の温度を計測して得られた計測温度に応じて、第ｋの溶接パスについて溶接が終了した後、解析モデルについて熱弾塑性解析を用いて計測温度に応じて残留応力を評価して推定残留応力を得、推定残留応力に応じて予め設定された溶接条件を変更して変更溶接条件とし、溶接条件変更手段によって予め設定された溶接条件が変更されると、第（ｋ＋１）の溶接パスについて変更溶接条件に応じて溶接を行うようにすれば。実際の構造物の溶接工程において残留応力を解析予測した結果に応じて構造物の溶接を精度よく制御することができ、残留応力を低減できることになる。
【００１６】
例えば、前記溶接条件変更手段は、前記推定残留応力と予め設定された許容応力とを比較して前記推定残留応力が前記許容応力以上であると、前記予め設定された溶接条件を変更する。
【００１７】
さらに、本発明では、前記計測温度に応じて前記解析モデルを修正して修正解析モデルを得る解析モデル修正手段を備え、前記残留応力評価手段は、解析モデル修正手段によって前記解析モデルが修正されると前記修正解析モデルを用いて前記推定残留応力を求める。
【００１８】
加えて、本発明では、前記解析モデルを用いて前記予め設定された溶接条件に応じて前記第ｋの溶接パスに起因する温度を計算して計算温度を得る温度計算手段と、前記計測温度と前記計算温度とを比較してその比較結果に応じて前記解析モデルを修正して修正解析モデルを得る解析モデル修正手段とを備え、前記残留応力評価手段は、前記解析モデル修正手段によって前記解析モデルが修正されると前記修正解析モデルを用いて前記推定残留応力を求めるようにしてもよい。
【００１９】
また、前記解析モデルを用いて前記予め設定された溶接条件に応じて前記第ｋの溶接パスに起因する温度を計算して計算温度を得る温度計算手段と、前記計測温度と前記計算温度とが異なる際前記解析モデルを修正する解析モデル修正手段とを備え、前記残留応力評価手段は、前記計測温度と前記計算温度とが一致した際の解析モデルを用いて前記（ｋ＋１）〜前記ｎの溶接パスに起因する温度を計算した計算結果に応じて熱弾塑性解析によって前記残留応力を評価するようにしてもよい。
【００２０】
なお、前記第１〜前記第ｎの溶接パスを複数のグループに分けて、該グループ毎に溶接を行うとともに前記残留応力の評価を行うようにしてもよい。
【００２１】
このようにして、残留応力と予め設定された許容応力とを比較して、推定残留応力が許容応力以上であると、溶接条件を変更するようにすれば、溶接過程で推定残留応力に応じて適宜溶接条件を変更して、構造物の残留応力を低減できる。また、第１〜第ｎの溶接パスを複数のグループの何れか一つにグループ化して、グループ毎に溶接を行うとともに残留応力の評価を行うようにすれば、溶接パス数が極めて多い多層溶接において、演算量を減らして、しかも構造物の残留応力を低減できる。
【００２２】
また、本発明によれば、第１及び第２の部材を溶接によって接合して構造物とする際、前記第１及び前記第２の部材の当接部に規定される開先において第１〜第ｎ（ｎは２以上の整数）の溶接パスについて順次溶接を行って多層溶接を行うようにした溶接システムにおいて、前記多層溶接を行う溶接装置と、前記溶接装置に通信回線を介して接続された残留応力評価装置とを有し、前記溶接装置には前記多層溶接を行う溶接手段と、前記予め定められた溶接条件に応じて第ｋ（ｋは１〜（ｎ−１）のいずれかの整数）の溶接パスについて溶接を行う過程で前記第１及び前記第２の部材の温度を計測して計測温度を得る温度計測手段と、前記残留応力評価装置と前記通信回線を介してデータの送受を行う第１の通信制御手段とが備えられ、前記残留応力評価装置には、前記第１の通信制御手段と前記通信回線を介してデータの送受を行う第２の通信制御手段と、前記第１の通信制御手段から受けた前記第１及び前記第２の部材に関するデータ及び予め設定された溶接条件に応じて解析モデルを生成する解析モデル生成手段と、前記第ｋの溶接パスについて溶接が終了した後、前記解析モデルについて熱弾塑性解析を用いて、前記第１の通信制御手段から受けた前記計測温度に応じて残留応力を評価して推定残留応力を得る残留応力評価手段と、前記推定残留応力に応じて前記予め設定された溶接条件を変更して変更溶接条件とする溶接条件変更手段とが備えられ、前記第２の通信制御手段は、前記溶接条件変更手段によって前記予め設定された溶接条件が変更されると、前記変更溶接条件を前記第１の通信制御手段に送り、前記溶接手段では第（ｋ＋１）の溶接パスについて前記変更溶接条件に応じて溶接を行うようにしたことを特徴とする残留応力評価を用いた溶接システムが得られる。
【００２３】
このようにして、通信回線を介して溶接装置と残留応力評価装置とを接続するようにすれば、一つの残留応力評価装置で、複数の溶接装置と遠隔的に残留応力の評価及び溶接条件の変更を行うことができ、施工現場で容易に構造物の残留応力を低減して溶接を行うことができることになる。
【００２４】
さらに、本発明によれば、第１及び第２の部材を溶接によって接合して構造物とする際、前記第１及び前記第２の部材の当接部に規定される開先において、第１〜第ｎ（ｎは２以上の整数）の溶接パスについて順次溶接を行って、多層溶接を行う溶接方法において、前記第１及び前記第２の部材について予め設定された溶接条件に応じた解析モデルを生成する解析モデル生成ステップと、前記予め定められた溶接条件に応じて第ｋ（ｋは１〜（ｎ−１）のいずれかの整数）の溶接パスについて溶接を行う過程で前記第１及び前記第２の部材の温度を計測して計測温度を得る温度計測ステップと、前記第ｋの溶接パスについて溶接が終了した後、前記解析モデルについて熱弾塑性解析を用いて前記計測温度に応じて残留応力を評価して推定残留応力を得る残留応力評価ステップと、前記推定残留応力に応じて前記予め設定された溶接条件を変更して変更溶接条件とする溶接条件変更ステップとを有し、前記溶接条件変更ステップによって前記予め設定された溶接条件が変更されると、第（ｋ＋１）の溶接パスについて、前記変更溶接条件に応じて溶接を行うようにしたことを特徴とする残留応力評価を用いた溶接方法が得られる。
【００２５】
例えば、前記溶接条件変更ステップでは、前記推定残留応力と予め設定された許容応力とを比較して前記推定残留応力が前記許容応力以上であると、前記予め設定された溶接条件を変更する。
【００２６】
さらに、前記計測温度に応じて前記解析モデルを修正して修正解析モデルを得る解析モデル修正ステップを有するようにしてもよく、この際には、前記残留応力評価ステップでは、前記解析モデル修正ステップで前記解析モデルが修正されると前記修正解析モデルを用いて前記推定残留応力を求める。
【００２７】
また、前記解析モデルを用いて前記予め設定された溶接条件に応じて前記第ｋの溶接パスに起因する温度を計算して計算温度を得る温度計算ステップと、前記計測温度と前記計算温度とを比較してその比較結果に応じて前記解析モデルを修正して修正解析モデルを得る解析モデル修正ステップとを有するようにしてもよく、この際、前記残留応力評価ステップでは、前記解析モデル修正ステップによって前記解析モデルが修正されると前記修正解析モデルを用いて前記推定残留応力を求める。
【００２８】
加えて、前記解析モデルを用いて前記予め設定された溶接条件に応じて前記第ｋの溶接パスに起因する温度を計算して計算温度を得る温度計算ステップと、前記計測温度と前記計算温度とが異なる際前記解析モデルを修正する解析モデル修正ステップとを有するようにしてもよく、その際、前記残留応力評価ステップでは、前記計測温度と前記計算温度とが一致した際の解析モデルを用いて前記（ｋ＋１）〜前記ｎの溶接パスに起因する温度を計算した計算結果に応じて熱弾塑性解析によって前記残留応力を評価する。なお、前記第１〜前記第ｎの溶接パスが複数のグループの何れか一つに属して、該グループ毎に溶接を行うとともに前記残留応力の評価を行うようにしてもよい。
【００２９】
また、本発明によれば、第１及び第２の部材を溶接によって接合して構造物とする際、前記第１及び前記第２の部材の当接部に規定される開先において第１〜第ｎ（ｎは２以上の整数）の溶接パスについて順次溶接を行って多層溶接を行う溶接方法において、前記第１及び前記第２の部材に関するデータを通信回線を介して送出する第１の送信ステップと、前記第１及び前記第２の部材に関するデータを受信して該第１及び該第２の部材に関するデータ及び予め設定された溶接条件に応じて解析モデルを生成する解析モデル生成ステップと、前記予め定められた溶接条件に応じて第ｋ（ｋは１〜（ｎ−１）のいずれかの整数）の溶接パスについて溶接を行う過程で前記第１及び前記第２の部材の温度を計測して計測温度を得る温度計測ステップと、前記第ｋの溶接パスについて溶接が終了した旨の通知を前記通信回線を介して受けるととともに前記計測温度を受けると、前記解析モデルについて熱弾塑性解析を用いて前記計測温度に応じて残留応力を評価して推定残留応力を得る残留応力評価ステップと、前記推定残留応力に応じて前記予め設定された溶接条件を変更して変更溶接条件とする溶接条件変更ステップと、前記溶接条件変更ステップで前記予め設定された溶接条件が変更されると前記変更溶接条件を前記通信回線を介して送信する第２の送信ステップと、前記変更溶接条件を受け、第（ｋ＋１）の溶接パスについて前記変更溶接条件に応じて溶接を行う溶接ステップとを有することを特徴とする残留応力評価を用いた溶接方法が得られる。
【００３０】
【発明の実施の形態】
以下、本発明の実施の形態について図面を参照して説明する。但し、この実施の形態に記載されている構成部品の寸法、材質、形状、その相対配置などは特に特定的な記載がない限り、この発明の範囲をそれのみに限定する趣旨ではなく、単なる説明例にすぎない。
【００３１】
図１を参照して、本発明による溶接システムについて説明する。この溶接システムは、溶接装置１０及び残留応力評価装置３１を備えている。図示の溶接装置１０は、溶接ロボット１１及び溶接制御装置（溶接機）１２を有しており、溶接ロボット１１によって、被溶接物１３が溶接されて、構造物となる。例えば、被溶接物１３は複数の第１及び第２の部材１３ａ及び１３ｂを有し、これら部材１３ａ及び１３ｂが接触する部分には、開先１３ｃが規定されている（開先１３ｃとは、部材１３ａ及び１３ｂに設けられた切り欠きがなす溝のことをいう）。そして、この開先１３ｃの内部が溶接されるべき部位とする。
【００３２】
溶接ロボット１１は溶接トーチ１１ａ及び駆動機構１１ｂを有しており、溶接トーチ１１ａは、開先１３ｃの延在方向に沿って溶接材送給装置（図示せず）から送給される溶接材（ワイヤー：図示せず）を溶融して、部材１３ａ及び１３ｂを溶接接合する。一方、駆動機構１１ｂは溶接制御装置１２に制御されて、溶接トーチ１１ａを３次元的（つまり、Ｘ，Ｙ，Ｚ軸方向）に駆動する。溶接に当たっては、溶接制御装置１２は、溶接トーチ１１ａに与える電流（Ｉ）及び電圧（Ｅ）を後述するようにして制御するとともに、駆動機構１１ｂを制御して、溶接トーチ１１ａの移動速度、つまり、溶接速度（ｖ）を制御する。部材１３ａ及び１３ｂの溶接に当たっては、所謂多層溶接が行われる。つまり、少なくとも２回の溶接パスを行って部材１３ａ及び１３ｂを接合することになる（言い換えると、ｎ（ｎは２以上の整数）回の溶接パスを行って部材１３ａ及び１３ｂを接合する）。
【００３３】
部材１３ａ及び１３ｂには、所定の位置（例えば、開先近傍の部材１３ａ及び１３ｂの表面（一面））に複数の温度センサー２１が配置され、温度センサー２１で計測された部材の温度は計測温度として、残留応力評価装置３１に与えられる。
【００３４】
ここで、図２も参照して、いま、部材１３ａ及び１３ｂとして、薄い平板（以下薄板平板と呼ぶ）同士を溶接する場合について説明する。なお、ここでは、ｎ＝５とする（つまり、５回の溶接パスによって、５層の多層盛溶接を行うものとする）。
【００３５】
溶接制御装置１２には、溶接条件として、電圧Ｅ、電流Ｉ、溶接速度ｖ、及び溶接材送給速度に対応する溶接肉盛形状Ｓが設定されており、これら電圧Ｅ、電流Ｉ、溶接速度ｖ、及び溶接肉盛形状Ｓは、複数設定されているものとし、溶接制御装置１２は、溶接条件に応じて溶接ロボット１１を制御する。ここでは、電圧Ｅ、電流Ｉ、溶接速度ｖ、及び溶接肉盛形状Ｓとして、Ｅｉ，Ｉｉ，ｖｉ，及びＳｉが設定されている。
【００３６】
まず、残留応力評価装置３１では、ｋ（変数であり、１〜ｎまでの整数）＝１として（ステップＰ１）、続いて、溶接制御装置１２に第ｋの溶接パスについて溶接を指示する溶接指示信号を送出する（ステップＰ２）。溶接制御装置１２では、この溶接指示信号に応答して、第ｋの溶接パスについて予め設定された溶接条件を選択する（以下この溶接条件を第ｋの溶接条件と呼ぶ：ステップＰ３）。例えば、電圧＝Ｅｋ，電流＝Ｉｋ，溶接速度＝ｖｋ，及び溶接肉盛形状＝Ｓｋとして、第ｋの溶接パスを、薄板平板１３ａ及び１３ｂの開先１３ｃに沿って規定して、駆動機構１１ｂを制御しつつ、溶接トーチ１１ａで溶接を行う。この際、溶接トーチ１１ａには電圧Ｅｋ及び電流Ｉｋが与えられ、駆動機構１１ｂは溶接トーチ１１ａを溶接速度ｖｋで移動させる。一方、溶接材送給装置からは溶接肉盛形状Ｓｋで規定される速度で溶接材が送給される。
【００３７】
そして、第ｋの溶接パス（ｋ＝１の際の溶接パスは図３に▲１▼で示す）について溶接の施工を行うと（ステップＰ４）、温度センサー２１で薄板平板１３ａ及び１３ｂの温度が計測されて（ステップＰ５）、計測温度Ｔｍ（ｍは温度センサー２１の個数に対応し、ｍ＝１〜Ｍ（Ｍは２以上の整数）である）として、残留応力評価装置３１に与えられる。
【００３８】
一方、残留応力評価装置３１では、薄板平板の溶接について、ＦＥＭ（有限要素法）を用いてモデル化して解析モデルを生成する（ステップＰ６）。つまり、残留応力評価装置３１には、薄板平板の溶接についてＦＥＭを用いてモデル化した解析モデルが基準解析モデルとして設定されている。残留応力評価装置３１では基準解析モデルに基づいて、前述の第ｋの溶接条件で、第ｋの溶接パスについて溶接を行った際の薄板平板の温度を解析温度として求める（ステップＰ７）。つまり、残留応力評価装置３１では、基準解析モデルについて、熱伝導解析を行って、温度履歴を求め、この温度履歴に応じて解析温度を得ることになる。この解析温度は、前述の温度センサー２１が配置された位置について求められる。この解析温度をＴｆｅｍで表す。
【００３９】
次に、残留応力評価装置３１は、Ｔｆｅｍ＝Ｔｍであるか否かを調べる（ステップＰ８）。なお、残留応力評価装置３１は望ましくはＴｆｅｍ＝Ｔｍであるか否かを調べることになるが、例えば、温度偏差許容値ΔＴを設定して、｜Ｔｆｅｍ−Ｔｍ｜＜ΔＴであるか否かを調べるようにしてもよい（以下の説明では、Ｔｆｅｍ＝Ｔｍであるか否かを調べるとして説明を行うが、｜Ｔｆｅｍ−Ｔｍ｜＜ΔＴであるか否かを調べるようにしても同様である）。Ｔｆｅｍ＝Ｔｍでないと、残留応力評価装置３１は、解析パラメータを変更して（ステップＰ９）、基準解析モデルを修正して修正解析モデルを得る。そして、再度、ステップＰ７及びＰ８を行う。このようにして、Ｔｆｅｍ＝Ｔｍとなるまで、解析パラメータを変更して、解析モデルを修正することになる。
【００４０】
上述のようにして、第ｋの溶接パスに関して、Ｔｆｅｍ＝Ｔｍとなった時点における解析モデルを用いて、残留応力評価装置３１では、第（ｋ＋１）の溶接パスから第ｎの溶接パスについて、第ｋの溶接条件で溶接を行ったと仮定して、薄板平板の温度解析を行って、解析温度を得る（ステップＰ１０）。その後、残留応力評価装置３１では、第（ｋ＋１）の溶接パス〜第ｎの溶接パスについての解析温度に応じて、つまり、温度履歴に応じて、熱弾塑性応力解析を行って、薄板平板に掛かる残留応力（推定残留応力）σＲを求める（ステップＰ１１）。そして、この推定残留応力σＲが予め設定された許容応力未満であるか否かを調べる（ステップＰ１２）。
【００４１】
推定残留応力σＲ≧許容応力であると、残留応力評価装置３１は、前述の第（ｋ＋１）〜第ｎの溶接パスについて溶接条件を変更する（ステップＰ１３）。溶接条件を変更する際には、まず、電圧Ｅｉ，電流Ｉｉ，溶接速度ｖｉ，溶接肉盛形状Ｓｉについて、その一つをｋから（ｋ＋１）〜ｎに順次変更する。つまり、電圧Ｅｉ，電流Ｉｉ，溶接速度ｖｉ，溶接肉盛形状Ｓｉの組み合わせについて、ｋから（ｋ＋１）に順次変更して、ステップＰ１０〜Ｐ１２を行う。そして、推定残留応力σＲ＜許容応力となる溶接条件を求めることになる。
【００４２】
一方、推定残留応力σＲ＜許容応力となると、残留応力評価装置３１はｋ＝ｋ＋１として（ステップＰ１４）、第ｎの溶接パスまで溶接が終了したか否かを判定して（ステップＰ１５）、第ｎの溶接パスまで終了していなければ、ステップＰ２に戻る。そして、残留応力評価装置３１は溶接制御装置１２に第（ｋ＋１）の溶接パスについて溶接を指示する溶接指示信号を送出する。この際には、前述のステップＰ１３で求められた溶接条件（以下変更溶接条件と呼ぶ）が溶接制御装置１２に与えられることになり、溶接制御装置１２で予め第（ｋ＋１）の溶接パスについて定められた溶接条件にかかわらず、変更溶接条件を第（ｋ＋１）の溶接条件として溶接を実行することになる。
【００４３】
その後、ステップＰ５で再び温度が計測されて、前述のようにして、ｋ＝ｎとなるまで、推定残留応力σＲと許容応力とが比較される。この際、前述のようにして、残留応力σＲ＜許容応力となるように溶接条件が変更されることになる。
【００４４】
このようにして、多層盛溶接を行うと、ｎ＝５の場合には、図３に示すように、多層盛溶接が行われることになる（図３において、▲２▼〜▲５▼はそれぞれ第２〜第５層を示す）。このようにして、薄板平板を溶接する際には、まず、第１〜第ｎの溶接パス毎にその溶接条件を予め設定する。そして、この溶接条件に応じて全溶接パスをモデル化して解析モデルを生成する。その後、第１の溶接パスについて溶接を行い、薄板平板の温度を計測する。この計測温度に応じて解析モデルを熱弾塑性解析によって残留応力を評価する。そして、推定残留応力が許容値（許容応力）以上であると、第１の溶接パス以降の溶接条件を変更することになる。
【００４５】
つまり、多層盛溶接を行う際には、第ｋの溶接パスまでについて、溶接を行った後、ＦＥＭを用いた解析モデルについて、ｎ層までの（つまり、全溶接パスについて）温度履歴に応じて熱弾塑性解析を行って、残留応力を推定する。この推定残留応力が許容応力未満となるように、溶接条件を変更して、第（ｋ＋１）の溶接パスについて溶接を行う。つまり、実際の構造物の溶接工程において、ＦＥＭを用いた解析モデルに対して温度に基づいて残留応力を解析予測して、その解析予測結果に応じて溶接条件を修正するようにしたから、構造物の溶接を行う際、構造物の残留応力を許容応力未満に精度制御することができることになる。
【００４６】
なお、薄板平板を溶接する際には、解析モデルとして２次元モデルを用いれば十分であり、より精度を向上させるためには、３次元モデルを用いることが好ましい。この際には、薄板平板の表面及び裏面で温度を計測する必要がある。一方、厚板平板を溶接する際には、解析モデルとして３次元モデルを用いる必要がある（つまり、厚板平板の場合には、Ｚ軸方向に対する温度分布を考慮する必要があるため、３次元モデルを用いることになる）。また、評価精度を上げるためには、多点で温度測定を行って、温度分布を導出することが望ましい（以下の例についても、評価精度を向上させるためには、多点温度計測を行うことが望ましい）。
【００４７】
また、溶接パス数が多い場合には、各溶接パスについて溶接を施工した後、前述のようにして残留応力評価を行うと、演算量が極めて多くなってしまう関係上、複数の溶接パスをグループ化した後、各グループについて溶接を施工した後、前述のようにして残留応力の評価を行えば、演算量を少なくすることができる。
【００４８】
ここで、平板以外の他の部材を溶接する際の例を挙げると、例えば、図４（ａ）に示す厚肉円筒（軸対称）２２を周面に沿って溶接する際には、溶接部位２２ａに関して、円筒の外周面及び内周面で温度計測を行い（図４（ｂ）参照）、図２で説明したようにして、残留応力評価を行いつつ、各溶接パスについて溶接を行うことになる。この際には、解析モデルとして、図４（ｃ）に示す２次元モデル（軸対称モデル）２２ｂを用いてもよく、３次元モデル（図示せず）を用いるようにしてもよい。そして、２次元モデルを用いるか３次元モデルを用いるかは溶接速度によって規定される。
【００４９】
同様にして、図５（ａ）に示すノズル２３をその薄肉部分で周面に沿って溶接する際には、溶接部位２３ａに関して、ノズルの外周面及び内周面で温度計測を行い（図５（ｂ）参照）、図２で説明したようにして、残留応力評価を行いつつ、各溶接パスについて溶接を行うことになる。この際には、解析モデルとして、図５（ｃ）に示す２次元モデル（軸対称モデル）２３ｂを用いてもよく、３次元モデルを用いるようにしてもよい。そして、２次元モデルを用いるか３次元モデルを用いるかは溶接速度によって規定される。
【００５０】
さらに、図６（ａ）に示すように、容器２４を貫通する配管等の貫通部２４ａを溶接する際には、その貫通部付近において、温度計測を行い（図６（ｂ）参照）、図２で説明したようにして、残留応力評価を行いつつ、各溶接パスについて溶接を行うことになる。この際には、解析モデルとして、図６（ｃ）に示す３次元モデル２４ｂが用いられる。
【００５１】
また、図７（ａ）に示すＴ字形継手２５を溶接する際には（所謂隅肉溶接）、溶接部位２５ａに関して、接合部付近で温度計測を行い（図７（ｂ）参照）、図２で説明したようにして、残留応力評価を行いつつ、各溶接パスについて溶接を行うことになる。この際には、解析モデルとして、図７（ｃ）に示す２次元モデル２５ｂを用いてもよく、３次元モデルを用いるようにしてもよい。３次元モデルを用いる際には、例えば、図７（ｄ）に示すようにして、溶接部位２５ａに沿って複数の箇所で温度計測が行われる。そして、２次元モデルを用いるか３次元モデルを用いるかは溶接速度によって規定される。
【００５２】
加えて、図８（ａ）に示すソケット２６を溶接する際には、溶接部位２６ａに関して、接合部付近で温度計測を行い（図８（ｂ）参照）、図２で説明したようにして、残留応力評価を行いつつ、各溶接パスについて溶接を行うことになる。この際には、解析モデルとして、図８（ｃ）に示す２次元モデル２６ｂを用いてもよく、３次元モデルを用いるようにしてもよい。そして、２次元モデルを用いるか３次元モデルを用いるかは溶接速度によって規定される。
【００５３】
ここで、図９を参照して、図示の例では、溶接ロボット１１及び溶接制御装置１２は、溶接施工場所に配置されており、溶接制御装置１２には通信制御装置４１が接続されている。さらに、温度センサー２１は温度計測器４２を介して通信制御装置４１に接続されている。通信制御装置４１は通信回線（図示の例では、通信衛星）５１を介してホスト装置６１に接続されている。ホスト装置６１には通信制御装置６２が備えられ、通信回線５１を介して通信制御装置４１とデータの送受を行う。そして、通信制御装置６２には残留応力評価装置３１が接続されている。
【００５４】
溶接施工場所で溶接を行う際には、溶接制御装置１２から通信制御装置４１を介して第１及び第２の部材１３ａ及び１３ｂに関するデータ及び溶接条件が通信制御装置６２に送られるとともに温度計測器４２で計測された部材の温度が通信制御装置４１を介して通信制御装置６２に送られる。残留応力評価装置３１では、図２で説明したようにして、残留応力の評価を行い、溶接条件の変更について、通信制御装置６２を介して通信制御装置４１に伝えることになる。そして、溶接条件に変更があれば、溶接制御装置１２は、変更後の溶接条件に応じて溶接ロボット１１を制御することになる。
【００５５】
【発明の効果】
以上説明したように、本発明では、第１及び第２の部材を溶接によって接合して構造物とする際、前記第１及び第２の部材について予め設定された溶接条件に応じた解析モデルを生成して、前記予め定められた溶接条件に応じて第ｋの溶接パスについて溶接を行う過程で、前記第１及び第２の部材の温度を計測して得られた計測温度に応じて、第ｋの溶接パスについて溶接が終了した後、前記解析モデルについて熱弾塑性解析を用いて残留応力を評価して推定残留応力を得、該推定残留応力に応じて前記予め設定された溶接条件を変更して変更溶接条件とし、溶接条件変更手段によって前記予め設定された溶接条件が変更されると、第（ｋ＋１）の溶接パスについて前記変更溶接条件に応じて溶接を行うようにしたので、実際の構造物の溶接工程において残留応力を解析予測した結果に応じて構造物の溶接を精度よく制御することができ、残留応力を低減できるという効果がある。
【００５６】
本発明では、推定残留応力と予め設定された許容応力とを比較して、推定残留応力が許容応力以上であると、溶接条件を変更するようにしたので、溶接過程で推定残留応力に応じて適宜溶接条件を変更して、構造物の残留応力を低減できるという効果がある。
【００５７】
本発明によれば、第１〜第ｎの溶接パスを複数のグループに分けることによりグループ化して、グループ毎に溶接を行うとともに残留応力の評価を行うようにしたから、溶接パス数が極めて多い多層溶接において、演算量を減らして、しかも構造物の残留応力を低減できるという効果がある。
【００５８】
本発明では、通信回線を介して溶接装置と残留応力評価装置とを接続するようにしたから、一つの残留応力評価装置で、複数の溶接装置と遠隔的に残留応力の評価及び溶接条件の変更を行うことができ、施工現場で容易に構造物の残留応力を低減して溶接を行うことができるという効果がある。
【図面の簡単な説明】
【図１】本発明による溶接システムの一例を示すブロック図である。
【図２】図１に示す溶接システムの動作を説明するためのフローチャートである。
【図３】薄板平板を多層溶接した際の一例を示す概要図である。
【図４】厚肉円筒を多層溶接する際の一例を説明するための概要図である。
【図５】厚肉円筒を多層溶接する際の一例を説明するための概要図である。
【図６】容器貫通部を多層溶接する際の一例を説明するための概要図である。
【図７】Ｔ字形継手を多層溶接する際の一例を説明するための概要図である。
【図８】ソケットを多層溶接する際の一例を説明するための概要図である。
【図９】本発明による溶接システムの他の例を示すブロック図である。
【符号の説明】
１０溶接装置
１１溶接ロボット
１２溶接制御装置（溶接機）
１３被溶接物
２１温度センサー
３１残留応力評価装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a welding system and a welding method for performing welding by reducing residual stress by using an evaluation result obtained by analyzing and evaluating residual stress generated by welding.
[0002]
[Prior art]
Generally, in a welded structure, residual stress and residual deformation may occur due to welding. If such residual stress exceeds a predetermined value, the residual stress is reduced as much as possible because the structure is adversely affected. There is a need to. Therefore, conventionally, analysis and prediction of residual stress, which will be generated in a welded structure, in advance using an analysis target such as a test piece has been performed.
[0003]
For example, a finite element method model is created for an object to be analyzed, residual stress is measured at several points on the surface of the object to be analyzed, and a residual strain pattern is assumed based on the actually measured residual stress. Then, a stress distribution for the residual strain pattern is obtained by applying the boundary element method to the analysis model. Next, after determining a coefficient to be the stress at the measurement point of the residual stress, the stress distribution of the entire analysis object is obtained by using the coefficient by the boundary element method (see Patent Document 1).
[0004]
Furthermore, a relational expression showing the mechanical properties of the material that composes the structure after giving the forced displacement data to the entire surface of the structure using the residual deformation amount obtained at any measurement point of the structure as the forced displacement data The stress-strain relationship of the entire structure is obtained in accordance with the equation (1), and the stress distribution of the entire structure is predicted (see Patent Document 2).
[0005]
In addition, by simulating the residual stress measurement by the notch method in detail by the finite element method and calculating the ratio between the measured value of the residual stress and the analysis value by the finite element method as a correction coefficient, this correction coefficient is The stress distribution is predicted by multiplying the residual stress distribution obtained by the element method (see Patent Document 3).
[0006]
[Patent Document 1]
JP-A-5-223661 (paragraphs (0030) to (0039), FIG. 1)
[0007]
[Patent Document 2]
JP-A-6-186141 (paragraphs (0008) to (0013), FIG. 1)
[0008]
[Patent Document 3]
JP-A-11-148875 (paragraphs (0016) to (0022), FIG. 3)
[0009]
[Problems to be solved by the invention]
However, in the residual stress analysis prediction methods described in Patent Documents 1 to 3, after welding is completed on an analysis target such as a test piece, the residual stress of the analysis target is measured, and the finite element method or the like is used. Is used to predict the stress distribution of the object to be analyzed and only consider this analysis result when welding the actual structure, and the object to be analyzed such as a test piece and the actual structure are not the same. Therefore, even if the stress distribution is analyzed and predicted for the analysis target, the stress distribution may be significantly different in the actual structure, and as a result, the residual stress exceeds a predetermined value and adversely affects the structure Sometimes.
[0010]
Furthermore, in the residual stress analysis prediction methods described in Patent Literatures 1 to 3, since the residual stress of an analysis target such as a test piece is measured, the analysis target is cut or a cut is made in the analysis target. In many cases, such an analytical prediction method cannot be used for analytically predicting the residual stress of an actual structure.
[0011]
In any case, the residual stress analysis and prediction methods described in Patent Documents 1 to 3 measure the residual stress of an object to be analyzed such as a test piece and perform the analysis and prediction of the stress distribution. There is a problem that it is difficult to analyze and predict the residual stress in the welding process of a structure.
[0012]
When the residual stress analysis prediction method described in Patent Documents 1 to 3 is used, the residual stress is analyzed and predicted in a welding process of an actual structure, and the structure is considered in consideration of the analysis prediction result. Can not control welding.
[0013]
An object of the present invention is to provide a welding system and a welding method capable of analyzing and predicting residual stress in an actual welding process of a structure and controlling welding of the structure according to the analysis and prediction result. .
[0014]
[Means for Solving the Problems]
According to the present invention, when the first and second members are joined by welding to form a structure, the first to n-th grooves are formed at the grooves defined by the contact portions of the first and second members. (N is an integer of 2 or more) In a welding system in which welding is sequentially performed on welding paths to perform multi-layer welding, an analysis model according to welding conditions set in advance for the first and second members is used. An analysis model generating unit that generates the first and the second welding paths in a process of performing welding on a k-th (k is an integer of 1 to (n−1)) welding path in accordance with the predetermined welding condition; Temperature measuring means for measuring the temperature of the second member to obtain a measured temperature; and, after welding is completed for the k-th welding pass, residual temperature is determined according to the measured temperature using thermo-elastic-plastic analysis for the analysis model. Estimate the stress to get the estimated residual stress And a welding condition changing means for changing the preset welding condition in accordance with the estimated residual stress to be a changed welding condition, wherein the welding condition changing means sets the predetermined welding condition as the changed welding condition. When the welding conditions are changed, a welding system using residual stress evaluation is obtained, wherein welding is performed for the (k + 1) th welding pass in accordance with the changed welding conditions.
[0015]
In this way, when the first and second members are joined to each other by welding to form a structure, an analysis model according to welding conditions set in advance for the first and second members is generated and determined in advance. In the process of performing the welding for the k-th welding pass according to the set welding conditions, the welding for the k-th welding pass is completed according to the measured temperature obtained by measuring the temperatures of the first and second members. After that, for the analysis model, the residual stress is evaluated according to the measured temperature using thermal elasto-plastic analysis to obtain the estimated residual stress, and the welding conditions set in advance according to the estimated residual stress are changed to the changed welding conditions. When the preset welding condition is changed by the welding condition changing means, welding is performed on the (k + 1) th welding path according to the changed welding condition. The welding of the structure can be accurately controlled in accordance with the result of analyzing and predicting the residual stress in the actual welding process of the structure, and the residual stress can be reduced.
[0016]
For example, the welding condition changing means compares the estimated residual stress with a preset allowable stress, and changes the preset welding condition if the estimated residual stress is equal to or greater than the allowable stress.
[0017]
Further, in the present invention, the apparatus further includes an analysis model correction unit that obtains a corrected analysis model by correcting the analysis model according to the measured temperature, wherein the residual stress evaluation unit corrects the analysis model by the analysis model correction unit. Then, the estimated residual stress is determined using the modified analysis model.
[0018]
In addition, in the present invention, a temperature calculating means for calculating a temperature resulting from the k-th welding pass in accordance with the preset welding conditions using the analysis model to obtain a calculated temperature, Analysis model correction means for comparing the calculated temperature with the calculated temperature and correcting the analysis model in accordance with the comparison result to obtain a corrected analysis model, wherein the residual stress evaluation means includes: Is corrected, the estimated residual stress may be obtained using the corrected analysis model.
[0019]
A temperature calculating unit that calculates a temperature caused by the k-th welding pass in accordance with the preset welding condition using the analysis model to obtain a calculated temperature; and the measured temperature and the calculated temperature are Analysis model correction means for correcting the analysis model when different from each other, wherein the residual stress evaluation means uses the analysis model obtained when the measured temperature and the calculated temperature coincide with each other to weld (k + 1) to n. The residual stress may be evaluated by a thermo-elasto-plastic analysis according to the calculation result of the temperature caused by the path.
[0020]
The first to n-th welding passes may be divided into a plurality of groups, welding may be performed for each of the groups, and the residual stress may be evaluated.
[0021]
In this way, the residual stress is compared with the preset allowable stress, and if the estimated residual stress is equal to or greater than the allowable stress, the welding conditions are changed. By appropriately changing the welding conditions, the residual stress of the structure can be reduced. Further, if the first to n-th welding passes are grouped into any one of a plurality of groups, and the welding is performed for each group and the residual stress is evaluated, the multi-pass welding having an extremely large number of welding passes is performed. In the above, the amount of calculation can be reduced, and the residual stress of the structure can be reduced.
[0022]
Further, according to the present invention, when the first and second members are joined by welding to form a structure, the first and second members are formed at the groove defined by the contact portion of the first and second members. In a welding system configured to sequentially perform welding on an nth (n is an integer of 2 or more) welding to perform multi-layer welding, a welding device for performing the multi-layer welding and a welding device connected to the welding device via a communication line. A welding device for performing the multi-layer welding, and a k-th (k is any one of 1 to (n−1)) according to the predetermined welding condition. A temperature measuring means for measuring the temperatures of the first and second members to obtain a measured temperature in the process of performing welding on the (integer) welding path, and transmitting and receiving data via the communication line with the residual stress evaluation device. And first communication control means for performing The stress-reducing evaluation device includes a second communication control means for transmitting and receiving data via the first communication control means and the communication line, and the first and second communication means received from the first communication control means. Analysis model generating means for generating an analysis model in accordance with the data relating to the second member and welding conditions set in advance, and after completion of welding for the k-th welding pass, thermo-elastic-plastic analysis for the analysis model A residual stress evaluation means for evaluating a residual stress according to the measured temperature received from the first communication control means to obtain an estimated residual stress, and changing the preset welding condition according to the estimated residual stress. And a welding condition changing means for changing the welding condition. The second communication control means changes the welding condition when the preset welding condition is changed by the welding condition changing means. A welding condition is sent to the first communication control means, and the welding means performs welding on the (k + 1) th welding path in accordance with the changed welding condition. Is obtained.
[0023]
In this way, if the welding device and the residual stress evaluation device are connected via the communication line, a single residual stress evaluation device can remotely evaluate the residual stress and evaluate welding conditions with a plurality of welding devices. Changes can be made, and welding can be easily performed at the construction site while reducing the residual stress of the structure.
[0024]
Further, according to the present invention, when the first and second members are joined by welding to form a structure, the first and second members are provided with a first groove at a contact portion defined by an abutting portion of the first and second members. In a welding method for performing multi-layer welding by sequentially performing welding on the nth (n is an integer of 2 or more) welding paths, an analysis model according to welding conditions preset for the first and second members. And a step of performing welding on a k-th (k is an integer of 1 to (n-1)) welding path in accordance with the predetermined welding condition. A temperature measuring step of measuring the temperature of the second member to obtain a measured temperature, and after welding is completed for the k-th welding pass, the thermodynamic elasto-plastic analysis is performed on the analysis model according to the measured temperature. Estimate residual stress and estimate residual A residual stress evaluation step of obtaining a force, and a welding condition changing step of changing the preset welding condition according to the estimated residual stress to be a changed welding condition, wherein the welding condition changing step sets the preset welding condition. When the changed welding condition is changed, a welding method using residual stress evaluation is obtained, wherein welding is performed for the (k + 1) th welding pass in accordance with the changed welding condition.
[0025]
For example, in the welding condition changing step, the preset welding condition is changed when the estimated residual stress is greater than or equal to the allowable stress by comparing the estimated residual stress with a preset allowable stress.
[0026]
Further, the method may include an analysis model correction step of correcting the analysis model in accordance with the measured temperature to obtain a corrected analysis model. In this case, in the residual stress evaluation step, the analysis model correction step When the analytical model is modified, the estimated residual stress is obtained using the modified analytical model.
[0027]
A temperature calculating step of calculating a temperature caused by the k-th welding pass according to the preset welding condition using the analysis model to obtain a calculated temperature; and calculating the measured temperature and the calculated temperature. An analysis model correction step of comparing and correcting the analysis model in accordance with the comparison result to obtain a corrected analysis model.In this case, in the residual stress evaluation step, the analysis model correction step When the analytical model is modified, the estimated residual stress is obtained using the modified analytical model.
[0028]
In addition, a temperature calculation step of calculating a temperature resulting from the k-th welding pass in accordance with the preset welding conditions using the analysis model to obtain a calculated temperature, the measurement temperature and the calculated temperature May have an analysis model correction step of correcting the analysis model when different, at that time, in the residual stress evaluation step, using the analysis model when the measured temperature and the calculated temperature match The residual stress is evaluated by thermo-elastic-plastic analysis according to the calculation result of calculating the temperature caused by the above (k + 1) to n welding paths. The first to n-th welding passes may belong to any one of a plurality of groups, perform welding for each group, and evaluate the residual stress.
[0029]
Further, according to the present invention, when the first and second members are joined by welding to form a structure, the first and second members are formed at the groove defined by the contact portion of the first and second members. In a welding method for performing multi-layer welding by sequentially performing welding on an n-th (n is an integer of 2 or more) welding path, a first transmission for transmitting data relating to the first and second members via a communication line. An analysis model generating step of receiving data on the first and second members and generating an analysis model in accordance with the data on the first and second members and a preset welding condition; The temperature of the first and second members is measured in a process of performing welding on a k-th (k is an integer from 1 to (n-1)) welding path according to the predetermined welding condition. Temperature measurement step to obtain the measured temperature And, when receiving the notification that the welding is completed for the k-th welding pass via the communication line and receiving the measured temperature, the thermodynamic elasto-plastic analysis is performed on the analysis model in accordance with the measured temperature. A residual stress evaluation step of evaluating a residual stress to obtain an estimated residual stress; a welding condition changing step of changing the preset welding condition according to the estimated residual stress to be a changed welding condition; and A second transmitting step of transmitting the changed welding condition via the communication line when the preset welding condition is changed in the step, receiving the changed welding condition, and setting the (k + 1) th welding path to And a welding step of performing welding in accordance with the changed welding conditions, whereby a welding method using residual stress evaluation is obtained.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, unless otherwise specified. It is only an example.
[0031]
A welding system according to the present invention will be described with reference to FIG. This welding system includes a welding device 10 and a residual stress evaluation device 31. The illustrated welding device 10 includes a welding robot 11 and a welding control device (welding machine) 12, and the welding robot 11 welds an object 13 to be a structure. For example, the workpiece 13 has a plurality of first and second members 13a and 13b, and a groove 13c is defined at a portion where the members 13a and 13b are in contact (the groove 13c is defined as: The groove formed by the notch provided in the members 13a and 13b). The inside of the groove 13c is to be welded.
[0032]
The welding robot 11 has a welding torch 11a and a drive mechanism 11b. The welding torch 11a is provided with a welding material (not shown) fed from a welding material feeding device (not shown) along the extending direction of the groove 13c. The members 13a and 13b are welded by melting a wire (not shown). On the other hand, the drive mechanism 11b is controlled by the welding control device 12, and drives the welding torch 11a three-dimensionally (that is, in the X, Y, and Z axis directions). In welding, the welding control device 12 controls the current (I) and the voltage (E) given to the welding torch 11a as described below, and controls the driving mechanism 11b to move the welding torch 11a, that is, the moving speed of the welding torch 11a. , Controlling the welding speed (v). When welding the members 13a and 13b, so-called multilayer welding is performed. That is, the members 13a and 13b are joined by performing at least two welding passes (in other words, the members 13a and 13b are joined by performing n (n is an integer of 2 or more) welding passes).
[0033]
In the members 13a and 13b, a plurality of temperature sensors 21 are arranged at predetermined positions (for example, the surfaces (one surface) of the members 13a and 13b near the groove), and the temperature of the members measured by the temperature sensor 21 is the measured temperature. Is given to the residual stress evaluation device 31.
[0034]
Here, a case where thin flat plates (hereinafter, referred to as thin flat plates) are welded to each other as the members 13a and 13b will be described with reference to FIG. Here, it is assumed that n = 5 (that is, five-layer multi-pass welding is performed by five welding passes).
[0035]
In the welding control device 12, a voltage E, a current I, a welding speed v, and a weld overlay S corresponding to a welding material feeding speed are set as welding conditions, and these voltage E, current I, and welding speed are set. It is assumed that a plurality of v and the weld overlay shape S are set, and the welding control device 12 controls the welding robot 11 according to welding conditions. Here, Ei, Ii, vi, and Si are set as the voltage E, the current I, the welding speed v, and the weld overlay S.
[0036]
First, the residual stress evaluation device 31 sets k (a variable, an integer from 1 to n) = 1 (step P1), and then gives a welding instruction to the welding control device 12 to instruct welding on the k-th welding pass. A signal is sent (step P2). In response to the welding instruction signal, the welding control device 12 selects a preset welding condition for the k-th welding pass (hereinafter, this welding condition is referred to as a k-th welding condition: step P3). For example, assuming that voltage = Ek, current = Ik, welding speed = vk, and weld overlay = Sk, the k-th welding path is defined along the groove 13c of the thin plates 13a and 13b, and the driving mechanism 11b is formed. Is controlled by the welding torch 11a. At this time, voltage Ek and current Ik are given to welding torch 11a, and drive mechanism 11b moves welding torch 11a at welding speed vk. On the other hand, the welding material is fed from the welding material feeding device at a speed defined by the weld overlay Sk.
[0037]
When welding is performed for the k-th welding pass (the welding pass when k = 1 is indicated by (1) in FIG. 3) (step P4), the temperature of the thin flat plates 13a and 13b is detected by the temperature sensor 21. It is measured (step P5), and given to the residual stress evaluation device 31 as a measured temperature Tm (m corresponds to the number of the temperature sensors 21 and m = 1 to M (M is an integer of 2 or more)).
[0038]
On the other hand, the residual stress evaluation device 31 generates an analysis model by modeling the welding of the thin plate using the FEM (finite element method) (step P6). That is, in the residual stress evaluation device 31, an analysis model of the welding of the thin plate using the FEM is set as the reference analysis model. Based on the reference analysis model, the residual stress evaluation device 31 obtains, as the analysis temperature, the temperature of the thin plate when welding is performed for the k-th welding pass under the k-th welding condition described above (step P7). That is, the residual stress evaluation device 31 performs a heat conduction analysis on the reference analysis model to obtain a temperature history, and obtains an analysis temperature according to the temperature history. This analysis temperature is obtained for the position where the above-mentioned temperature sensor 21 is arranged. This analysis temperature is represented by Tfem.
[0039]
Next, the residual stress evaluation device 31 checks whether or not Tfem = Tm (step P8). The residual stress evaluation device 31 desirably checks whether or not Tfem = Tm. For example, by setting a temperature deviation allowable value ΔT, it is determined whether or not | Tfem−Tm | <ΔT. It may be checked (in the following description, it is assumed that Tfem = Tm is checked, but it is the same as checking whether | Tfem−Tm | <ΔT). . If Tfem is not equal to Tm, the residual stress evaluation device 31 changes the analysis parameters (Step P9) and corrects the reference analysis model to obtain a corrected analysis model. Then, steps P7 and P8 are performed again. In this way, the analysis parameters are changed and the analysis model is modified until Tfem = Tm.
[0040]
As described above, with respect to the k-th welding pass, the residual stress evaluation device 31 uses the analysis model at the time when Tfem = Tm to determine the k-th welding pass from the (k + 1) -th welding pass to the n-th welding pass. Assuming that welding was performed under the welding condition of k, temperature analysis of the thin plate is performed to obtain an analysis temperature (step P10). Thereafter, the residual stress evaluation device 31 performs a thermo-elasto-plastic stress analysis in accordance with the analysis temperature for the (k + 1) th welding pass to the n-th welding pass, that is, in accordance with the temperature history, to obtain a thin plate. The applied residual stress (estimated residual stress) σR is obtained (step P11). Then, it is checked whether or not the estimated residual stress σR is less than a preset allowable stress (step P12).
[0041]
If the estimated residual stress σR ≧ permissible stress, the residual stress evaluation device 31 changes the welding conditions for the (k + 1) th to nth welding passes described above (step P13). When changing the welding conditions, first, one of the voltage Ei, the current Ii, the welding speed vi, and the weld overlay Si is changed sequentially from k to (k + 1) to n. That is, steps P10 to P12 are performed by sequentially changing the combination of the voltage Ei, the current Ii, the welding speed vi, and the weld overlay shape Si from k to (k + 1). Then, welding conditions that satisfy the estimated residual stress σR <allowable stress are determined.
[0042]
On the other hand, when the estimated residual stress σR <allowable stress, the residual stress evaluation device 31 sets k = k + 1 (step P14), determines whether or not the welding has been completed up to the n-th welding pass (step P15). If the welding pass of n has not been completed, the process returns to Step P2. Then, the residual stress evaluation device 31 sends a welding instruction signal for instructing welding on the (k + 1) th welding pass to the welding control device 12. At this time, the welding conditions (hereinafter referred to as changed welding conditions) determined in the above-described step P13 are given to the welding control device 12, and the welding control device 12 determines the (k + 1) th welding path in advance. Irrespective of the set welding condition, the welding is executed with the changed welding condition as the (k + 1) th welding condition.
[0043]
Thereafter, the temperature is measured again in step P5, and the estimated residual stress σR and the allowable stress are compared as described above until k = n. At this time, as described above, the welding conditions are changed so that the residual stress σR <the allowable stress.
[0044]
When the multi-pass welding is performed in this way, when n = 5, the multi-pass welding is performed as shown in FIG. 3 (in FIG. 3, (2) to (5) indicate The second to fifth layers are shown). When welding thin flat plates in this way, first, the welding conditions are set in advance for each of the first to n-th welding passes. Then, an analysis model is generated by modeling all welding paths according to the welding conditions. Thereafter, welding is performed for the first welding pass, and the temperature of the thin plate is measured. The residual stress is evaluated by thermo-elasto-plastic analysis of the analytical model according to the measured temperature. If the estimated residual stress is equal to or more than the allowable value (allowable stress), the welding conditions after the first welding pass are changed.
[0045]
That is, when performing multi-pass welding, after performing welding up to the k-th welding pass, an analysis model using FEM is performed according to the temperature history up to the n-th layer (that is, for all welding passes). A thermal elasto-plastic analysis is performed to estimate the residual stress. The welding conditions are changed so that the estimated residual stress is less than the allowable stress, and welding is performed for the (k + 1) th welding pass. That is, in the actual welding process of a structure, the residual stress is analyzed and predicted based on the temperature with respect to the analysis model using the FEM, and the welding conditions are modified according to the analysis prediction result. When welding an object, it is possible to precisely control the residual stress of the structure to less than the allowable stress.
[0046]
When welding a thin plate, it is sufficient to use a two-dimensional model as an analysis model, and it is preferable to use a three-dimensional model in order to further improve accuracy. In this case, it is necessary to measure the temperature on the front and back surfaces of the thin flat plate. On the other hand, when welding a thick flat plate, it is necessary to use a three-dimensional model as an analysis model (that is, in the case of a thick flat plate, it is necessary to consider the temperature distribution in the Z-axis direction. Model will be used). In order to improve the evaluation accuracy, it is desirable to measure the temperature at multiple points to derive the temperature distribution. (In the following examples, it is necessary to perform the multipoint temperature measurement in order to improve the evaluation accuracy. Is desirable).
[0047]
In addition, when the number of welding passes is large, if the residual stress evaluation is performed as described above after welding is performed for each welding pass, a plurality of welding passes are grouped due to an extremely large amount of calculation. After the welding, the welding is performed for each group, and the residual stress is evaluated as described above, so that the amount of calculation can be reduced.
[0048]
Here, as an example of welding other members than a flat plate, for example, when welding a thick-walled cylinder (axially symmetric) 22 shown in FIG. Regarding 22a, the temperature was measured on the outer peripheral surface and the inner peripheral surface of the cylinder (see FIG. 4B), and as described with reference to FIG. Become. In this case, a two-dimensional model (axisymmetric model) 22b shown in FIG. 4C or a three-dimensional model (not shown) may be used as the analysis model. Whether the two-dimensional model or the three-dimensional model is used is defined by the welding speed.
[0049]
Similarly, when the nozzle 23 shown in FIG. 5A is welded along the peripheral surface at the thin portion thereof, the temperature is measured on the outer peripheral surface and the inner peripheral surface of the nozzle with respect to the welded portion 23a (see FIG. 5). (Refer to (b)), as described with reference to FIG. 2, welding is performed for each welding pass while the residual stress is evaluated. In this case, a two-dimensional model (axisymmetric model) 23b shown in FIG. 5C or a three-dimensional model may be used as the analysis model. Whether the two-dimensional model or the three-dimensional model is used is defined by the welding speed.
[0050]
Further, as shown in FIG. 6 (a), when welding a penetration 24a such as a pipe penetrating the container 24, temperature measurement is performed in the vicinity of the penetration (see FIG. 6 (b)). As described in 2, the welding is performed for each welding pass while the residual stress is evaluated. In this case, a three-dimensional model 24b shown in FIG. 6C is used as the analysis model.
[0051]
When welding the T-shaped joint 25 shown in FIG. 7A (so-called fillet welding), the temperature of the welded portion 25a is measured near the joint (see FIG. 7B), and FIG. As described above, welding is performed for each welding pass while the residual stress is evaluated. In this case, a two-dimensional model 25b shown in FIG. 7C or a three-dimensional model may be used as the analysis model. When a three-dimensional model is used, for example, as shown in FIG. 7D, temperature measurement is performed at a plurality of locations along the welding region 25a. Whether the two-dimensional model or the three-dimensional model is used is defined by the welding speed.
[0052]
In addition, when the socket 26 shown in FIG. 8A is welded, the temperature of the welded portion 26a is measured near the joint (see FIG. 8B), and as described with reference to FIG. While performing the residual stress evaluation, welding is performed for each welding pass. In this case, a two-dimensional model 26b shown in FIG. 8C or a three-dimensional model may be used as the analysis model. Whether the two-dimensional model or the three-dimensional model is used is defined by the welding speed.
[0053]
Here, referring to FIG. 9, in the illustrated example, the welding robot 11 and the welding control device 12 are arranged at a welding work place, and the communication control device 41 is connected to the welding control device 12. Further, the temperature sensor 21 is connected to a communication control device 41 via a temperature measuring device 42. The communication control device 41 is connected to a host device 61 via a communication line (a communication satellite in the illustrated example) 51. The host device 61 is provided with a communication control device 62 for transmitting and receiving data to and from the communication control device 41 via the communication line 51. The residual stress evaluation device 31 is connected to the communication control device 62.
[0054]
When welding is performed at a welding work place, data and welding conditions regarding the first and second members 13a and 13b are sent from the welding control device 12 via the communication control device 41 to the communication control device 62, and the temperature measurement device is used. The temperature of the member measured at 42 is sent to the communication control device 62 via the communication control device 41. The residual stress evaluation device 31 evaluates the residual stress as described with reference to FIG. 2 and notifies the communication control device 41 via the communication control device 62 of the change in the welding condition. If the welding conditions are changed, the welding control device 12 controls the welding robot 11 according to the changed welding conditions.
[0055]
【The invention's effect】
As described above, in the present invention, when the first and second members are joined by welding to form a structure, an analysis model according to welding conditions preset for the first and second members is used. In the process of generating and performing welding on the k-th welding pass in accordance with the predetermined welding condition, the first and second members are measured in accordance with a measured temperature obtained by measuring the temperature thereof. After welding is completed for the k welding passes, the residual stress is evaluated by using thermo-elastic-plastic analysis for the analytical model to obtain an estimated residual stress, and the preset welding conditions are changed according to the estimated residual stress. When the preset welding condition is changed by the welding condition changing means, the welding is performed for the (k + 1) th welding pass in accordance with the changed welding condition. Welding of structures The welding of the structure can be precisely controlled according to a result of the residual stress was analyzed expected in extent, there is an effect of reducing the residual stress.
[0056]
In the present invention, the estimated residual stress is compared with a preset allowable stress, and when the estimated residual stress is equal to or more than the allowable stress, the welding conditions are changed. There is an effect that the residual stress of the structure can be reduced by appropriately changing the welding conditions.
[0057]
According to the present invention, the first to n-th welding passes are grouped by dividing them into a plurality of groups, and the welding is performed for each group and the residual stress is evaluated. Therefore, the number of welding passes is extremely large. In multi-layer welding, there is an effect that the amount of calculation can be reduced and the residual stress of the structure can be reduced.
[0058]
In the present invention, the welding device and the residual stress evaluation device are connected via the communication line, so that one residual stress evaluation device can remotely evaluate the residual stress and change the welding conditions with a plurality of welding devices. Thus, there is an effect that welding can be performed while easily reducing the residual stress of the structure at the construction site.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of a welding system according to the present invention.
FIG. 2 is a flowchart for explaining the operation of the welding system shown in FIG.
FIG. 3 is a schematic view showing an example when a thin flat plate is subjected to multilayer welding.
FIG. 4 is a schematic diagram for explaining an example of multi-layer welding of a thick-walled cylinder.
FIG. 5 is a schematic diagram for explaining an example of multi-layer welding of a thick-walled cylinder.
FIG. 6 is a schematic diagram for explaining an example of multi-layer welding of a container penetration portion.
FIG. 7 is a schematic diagram for explaining an example of multi-layer welding of a T-shaped joint.
FIG. 8 is a schematic diagram for explaining an example of multi-layer welding of a socket.
FIG. 9 is a block diagram showing another example of the welding system according to the present invention.
[Explanation of symbols]
10 Welding equipment
11 Welding robot
12 Welding control device (welding machine)
13 Workpiece
21 Temperature sensor
31 Residual stress evaluation device

Claims

When the first and second members are joined by welding to form a structure, first to n-th (n is 2 or more) at the groove defined by the contact portion of the first and second members. Welding is performed sequentially for the welding passes of (integer), and a multi-layer welding is performed.
Analysis model generation means for generating an analysis model according to welding conditions set in advance for the first and second members;
The temperature of the first and second members is measured in a process of performing welding on a k-th (k is an integer from 1 to (n-1)) welding path according to the predetermined welding condition. Temperature measuring means for obtaining a measured temperature by
After welding is completed for the k-th welding pass, residual stress evaluation means for evaluating residual stress according to the measured temperature using thermal elasto-plastic analysis for the analysis model to obtain an estimated residual stress,
Welding condition changing means to change the preset welding conditions according to the estimated residual stress and to change welding conditions,
When the preset welding condition is changed by the welding condition changing means, welding is performed for the (k + 1) th welding path in accordance with the changed welding condition. The welding system used.

The welding condition changing means compares the estimated residual stress with a preset allowable stress, and changes the preset welding condition when the estimated residual stress is equal to or more than the allowable stress. A welding system using the residual stress evaluation according to claim 1.

An analysis model correcting unit that corrects the analysis model according to the measured temperature to obtain a corrected analysis model,
2. The residual stress according to claim 1, wherein the residual stress evaluation unit obtains the estimated residual stress using the corrected analysis model when the analysis model is corrected by the analysis model correction unit. 3. Welding system using evaluation.

Temperature calculation means for calculating a temperature resulting from the k-th welding pass in accordance with the preset welding conditions using the analysis model to obtain a calculated temperature;
Analysis model correction means for comparing the measured temperature and the calculated temperature and correcting the analysis model in accordance with the comparison result to obtain a corrected analysis model,
2. The residual stress according to claim 1, wherein the residual stress evaluation unit obtains the estimated residual stress using the corrected analysis model when the analysis model is corrected by the analysis model correction unit. 3. Welding system using evaluation.

Temperature calculation means for calculating a temperature resulting from the k-th welding pass in accordance with the preset welding conditions using the analysis model to obtain a calculated temperature;
Analysis model correction means for correcting the analysis model when the measured temperature and the calculated temperature are different,
The residual stress evaluation means calculates thermoelastic plasticity according to a calculation result of calculating a temperature caused by the (k + 1) to n welding paths by using an analysis model when the measured temperature and the calculated temperature match. The welding system according to claim 1, wherein the residual stress is evaluated by analysis.

2. The method according to claim 1, wherein the first to n-th welding passes belong to any one of a plurality of groups, and the welding is performed for each of the groups and the residual stress is evaluated. 4. A welding system using the residual stress evaluation described in 1.

When joining the first and second members by welding to form a structure, first to n-th (n is 2 or more) at the groove defined by the contact portion of the first and second members. Integer) welding paths are sequentially welded to perform multi-layer welding.
A welding device for performing the multi-layer welding,
Having a residual stress evaluation device connected to the welding device via a communication line,
Welding means for performing the multi-layer welding in the welding apparatus, and a step of performing welding on a k-th (k is an integer of 1 to (n-1)) welding path in accordance with the predetermined welding conditions; A temperature measuring means for measuring the temperature of the first and second members to obtain a measured temperature, and a first communication control means for transmitting and receiving data via the residual stress evaluation device and the communication line. Equipped,
The residual stress evaluation device includes a first communication control unit, a second communication control unit for transmitting and receiving data via the communication line, and the first and the second communication control units received from the first communication control unit. Analysis model generating means for generating an analysis model in accordance with data relating to the second member and welding conditions set in advance, and after completion of welding for the k-th welding pass, thermo-elastic-plastic analysis is used for the analysis model. A residual stress estimating means for estimating a residual stress in accordance with the measured temperature received from the first communication control means to obtain an estimated residual stress, and the welding condition set in advance in accordance with the estimated residual stress. A welding condition changing means for changing and changing the welding condition is provided;
When the preset welding condition is changed by the welding condition changing means, the second communication control means sends the changed welding condition to the first communication control means. A welding system using residual stress evaluation, wherein welding is performed in accordance with the changed welding conditions for the welding pass of (1).

When the first and second members are joined by welding to form a structure, first to n-th (n is 2 or more) at the groove defined by the contact portion of the first and second members. In the welding method of sequentially performing welding for the welding paths of
An analysis model generating step of generating an analysis model according to a welding condition set in advance for the first and second members;
The temperature of the first and second members is measured in a process of performing welding on a k-th (k is an integer from 1 to (n-1)) welding path according to the predetermined welding condition. A temperature measurement step of obtaining a measurement temperature by performing
After welding is completed for the k-th welding pass, a residual stress evaluation step of evaluating residual stress according to the measured temperature using thermo-elasto-plastic analysis for the analysis model to obtain an estimated residual stress,
A welding condition changing step of changing the preset welding condition in accordance with the estimated residual stress and changing the welding condition to a changed welding condition,
When the preset welding condition is changed in the welding condition changing step, welding is performed for the (k + 1) th welding path in accordance with the changed welding condition. The welding method used.

In the welding condition changing step, the preset welding condition is changed when the estimated residual stress is equal to or more than the allowable stress by comparing the estimated residual stress with a preset allowable stress. A welding method using the residual stress evaluation according to claim 8.

Further, an analysis model correction step of correcting the analysis model according to the measured temperature to obtain a corrected analysis model,
9. The residual stress according to claim 8, wherein in the residual stress evaluation step, when the analytical model is modified in the analytical model modifying step, the estimated residual stress is obtained using the modified analytical model. Welding method using evaluation.

A temperature calculation step of calculating a temperature caused by the k-th welding pass according to the preset welding condition using the analysis model to obtain a calculated temperature;
An analysis model correction step of comparing the measured temperature and the calculated temperature and correcting the analysis model according to the comparison result to obtain a corrected analysis model;
9. The residual stress according to claim 8, wherein in the residual stress evaluation step, when the analytical model is modified by the analytical model modifying step, the estimated residual stress is obtained using the modified analytical model. Welding method using evaluation.

A temperature calculation step of calculating a temperature caused by the k-th welding pass according to the preset welding condition using the analysis model to obtain a calculated temperature;
An analysis model correction step of correcting the analysis model when the measured temperature and the calculated temperature are different,
In the residual stress evaluation step, a thermo-elastic plasticity is calculated according to a calculation result of calculating a temperature caused by the (k + 1) to n welding paths by using an analysis model when the measured temperature matches the calculated temperature. The welding method according to claim 8, wherein the residual stress is evaluated by analysis.

9. The method according to claim 8, wherein the first to n-th welding passes belong to one of a plurality of groups, and the welding is performed for each of the groups and the residual stress is evaluated. A welding method using the residual stress evaluation described in 1.

When joining the first and second members by welding to form a structure, first to n-th (n is 2 or more) at the groove defined by the contact portion of the first and second members. In the welding method of performing multi-layer welding by sequentially performing welding on (integer) welding paths,
A first transmission step of transmitting data relating to the first and second members via a communication line;
An analysis model generating step of receiving data on the first and second members and generating an analysis model in accordance with the data on the first and second members and welding conditions set in advance;
The temperature of the first and second members is measured in a process of performing welding on a k-th (k is an integer from 1 to (n-1)) welding path according to the predetermined welding condition. A temperature measurement step of obtaining a measurement temperature by performing
When receiving the notification that the welding has been completed for the k-th welding pass via the communication line and receiving the measured temperature, the analysis model uses a thermo-elasto-plastic analysis to determine a residual stress according to the measured temperature. Evaluating the residual stress to obtain an estimated residual stress,
A welding condition changing step of changing the preset welding condition in accordance with the estimated residual stress and changing the welding condition to a changed welding condition;
When the preset welding condition is changed in the welding condition changing step, a second transmitting step of transmitting the changed welding condition via the communication line;
A welding step of receiving the changed welding condition and performing welding in accordance with the changed welding condition for a (k + 1) th welding pass.