JP4300066B2

JP4300066B2 - Seal welding method for small-diameter holes and automatic welding equipment

Info

Publication number: JP4300066B2
Application number: JP2003189940A
Authority: JP
Inventors: 昭慈今永; 光明羽田; 正寿稲垣; 修渡辺; 良樹杣友; 茂樹平澤
Original assignee: Hitachi Ltd; Hitachi Maxell Energy Ltd
Current assignee: Hitachi Ltd; Hitachi Maxell Energy Ltd
Priority date: 2003-07-02
Filing date: 2003-07-02
Publication date: 2009-07-22
Anticipated expiration: 2023-07-02
Also published as: JP2005021939A

Description

【０００１】
【発明の属する技術分野】
本発明は、小物容器の蓋板又は平板である金属母材の表面に設けられた小径穴の封止溶接法及びその自動溶接装置に関する。
【０００２】
【従来の技術】
金属製の容器表面に設けられた小径穴を封止溶接する従来技術が幾つかある。例えば、特許文献１の密閉型電池では、電解液を注入した後、小径穴にアルミニウム製の球状の封止栓を押圧し、超音波溶接で封止することが提案されている。又、特許文献２の角形密閉式蓄電池及びその製造方法、特許文献３の密閉型電池では、小径穴に封止栓を挿入し、レーザー溶接で封止することが提案されている。また、特許文献４の容器における注入口の封止方法及び密閉容器では、注入口にステンレス製の球状の封止部材を押し込み、手段の異なる抵抗溶接とレーザー溶接の二段階で封止溶接することが提案されている。
【０００３】
【特許文献１】
特開平８−４５４８８号公報（特許請求の範囲）
【特許文献２】
特開平１１−２５９３６号公報（特許請求の範囲）
【特許文献３】
特開平１１−１４９９１５号公報（特許請求の範囲）
【特許文献４】
特開２００２−２３９７６２号公報（特許請求の範囲）
【０００４】
【発明が解決しようとする課題】
特許文献１〜４はいずれも、超音波溶接やレーザー溶接等により封止栓の外周と蓋板表面との継ぎ部のみを溶融させる浅い溶け込みの円周溶接である。隙間腐食や強度低下を抑制するには、裏面側の継ぎ部に未接合部を残さない方が良い。また、継ぎ部に隙間が生じていたり、注入穴部分に溶液が付着していたりすると、溶接ビードの形成に乱れが生じ易く、ピンホールの発生によって未接合部分が生じ易い。
【０００５】
本発明の目的は、小物容器の蓋板又は平板である金属母材の表面にある小径穴を短時間で容易に溶接して確実に完全封止でき、溶接後の表面が平滑で高品質な溶接部を得ることができる小径穴の封止溶接法及びその自動溶接装置を提供することにある。
【０００６】
【課題を解決するための手段】
本発明は、小物容器の蓋板又は平板である金属母材の表面に設けられた小径穴に封止栓を挿入し、該小径穴を封止する封止溶接法において、前記金属母材の裏面側に前記小径穴近傍が平面形状で円形又は多角形である薄肉部を形成し、前記封止栓の頭部に前記小径穴の内径より大きい外径で円形又は多角形である張り出し部を形成し、該封止栓を前記小径穴へ挿入後に、該封止栓と前記金属母材の薄肉部とをアーク熱源により溶融して封止溶接することを特徴とする。
【０００７】
また、上述の封止溶接法において、前記封止栓を前記金属母材の小径穴に挿入する挿入工程と、栓挿入後の前記金属母材を溶接工程に搬入及び所定位置に配置し、非消耗性電極による溶接トーチを前記封止栓の上部中央位置に移動及び位置決めする位置決め工程と、前記溶接トーチからアーク熱源を前記封止栓の頭部に与えて前記小径穴を封止溶接する溶接工程と、該封止溶接後に前記金属母材を搬出する搬出工程とを順次実行することを特徴とする。さらに、前記溶接工程又は前記搬出工程の後に品質検査工程を設けて、前記金属母材の封止溶接部の良否を検査するようにするとよい。
【０００８】
また、本発明の自動溶接装置は、封止栓を金属母材の小径穴に挿入する栓挿入装置と、栓挿入後の前記金属母材を溶接工程に搬入及び溶接終了後に搬出する母材搬入搬出装置と、前記金属母材を所定位置に配置し、非消耗性電極による溶接トーチを前記封止栓の上部中央位置に移動及び位置決めするトーチ位置決め装置と、該溶接トーチと前記金属母材との間に所定溶接条件のアーク熱源を供給する溶接電源と、前記母材搬入搬出装置，トーチ位置決め装置，溶接電源を管理及び制御する制御盤とを備えていることを特徴とする。
【０００９】
また、上述の自動溶接装置において、前記溶接トーチを自動交換するトーチ交換装置又は溶接トーチ内のタングステン電極棒を自動交換する電極交換装置と、前記封止溶接の繰返し回数を設定する回数カウント装置とをさらに設け、予め指定回数の封止溶接が終了した時に溶接動作を一時停止して、前記溶接トーチをトーチ交換装置によって自動交換し、又は前記溶接トーチ内のタングステン電極棒を電極交換装置によって自動交換し、該交換完了後に前記溶接動作を再開することを特徴とする。溶接終了後の前記金属母材を搬出する毎に封止溶接部の良否を検査する溶接検査装置を設けるとなおよい。
【００１０】
すなわち、本発明によれば、短時間のアーク加熱によって封止栓と薄肉部とを一体溶融でき、少ないエネルギーで溶融範囲のバラツキの極めて少ない穴封止の溶接部を良好に得ることができる。
【００１１】
特に、封止栓の頭部に短時間で溶融可能な大きさの円形又は多角形の張り出し部分を予め形成することによって、封止栓の頭部を治具で簡単につかんで小径穴へ圧入することができ、張り出し部分の下面と小径穴周囲の上面とを確実に密着させることができるばかりでなく、金属母材の表面高さより突き出した栓頭部にアーク熱源を加え易く、短時間の加熱溶融により、溶接後の表面が平滑で高品質な溶接部を得ることができる。
【００１２】
前記アーク熱源は、非消耗性電極によるＴＩＧアーク溶接であり、該アーク溶接による溶接条件は電流Ｉ（Ａ）と溶接時間Ｔ（ｍｓ）との関係式に基づいて溶接電源に設定して出力させることにより、適正なエネルギー条件で確実に封止溶接することができるばかりでなく、溶接条件及び溶接品質の管理が容易となる。
【００１３】
また、前記封止栓を前記金属母材の小径穴に挿入する挿入工程と、栓挿入後の前記金属母材を溶接工程に搬入及び所定位置に配置し、非消耗性電極による溶接トーチを前記封止栓の上部中央位置に移動及び位置決めする位置決め工程と、前記溶接トーチからアーク熱源を前記封止栓の頭部から与えて前記小径穴を封止溶接する溶接工程と、該封止溶接後に前記金属母材を搬出する搬出工程とを順次実行することにより、小物容器の蓋板又は平板である金属母材の搬送から小径穴の封止溶接及び溶接後に搬出するまでの一連動作を自動で繰返し実行でき、封止溶接の対象製品を確実に量産することができる。
【００１４】
さらに、前記溶接工程又は搬出工程の後に品質検査工程を設けて金属母材の封止溶接部の良否を検査することにより、不良品の有無を判定して合格品のみを選択，認定し、品質の良いものを供給できると共に、不良率の低減対策にも活用することが可能である。
【００１５】
また、本発明の自動溶接装置によれば、量産対応の自動溶接設備が実現でき、対象製品の金属母材の搬送から小径穴の封止溶接及び溶接後の搬出まで一連の溶接動作を自動で繰返し実行することができる。
【００１６】
また、溶接トーチを自動交換するトーチ交換装置又は溶接トーチ内のタングステン電極棒を自動交換する電極交換装置と、前記封止溶接の繰返し回数を設定する回数カウント装置とをさらに設けることにより、アーク溶接の繰返し使用によって消耗した電極を短時間で新しい電極又は新しい電極を有する溶接トーチに短時間で自動交換することができる。特に、予め指定回数の封止溶接を終了した時に溶接動作を一時停止して、前記溶接トーチをトーチ交換装置によって自動交換し、又は前記溶接トーチ内のタングステン電極棒を電極交換装置によって自動交換し、該交換完了後に、前記溶接ライン及び封止溶接の動作を再開することにより、一時停止の時間短縮，繰返し使用回数の設定と管理，装置稼働時間率の管理，安定なアーク溶接の再現，溶接品質の保持を容易にすることができる。
【００１７】
さらに、溶接終了後の前記金属母材を搬出する毎に封止溶接部の良否を検査する溶接検査装置を設けることにより、量産対応の品質検査が可能になり、不良品の有無を判定して合格品のみを選択，認定し、品質の良いものを供給することができる。
【００１８】
【発明の実施の形態】
図１は、本発明の封止溶接法に係わる小物容器の斜視図である。小物容器１の上部にある金属母材２の表面に小径穴４が設けられている。この小径穴４には、封止栓３が挿入され、封止溶接される。図２は、小径穴４を有する平板の金属母材２を示す上面図である。
【００１９】
図３は、本発明の封止溶接法に係わる小径穴の形状及びこの小径穴に挿入する封止栓の一実施形態を示す断面図である。また、図４は、小径穴の外周部に形成するザグリ溝の形状が異なる断面図及び平面図である。すなわち、図３に示すように、小径穴４の表側外周部分に金属母材２の板厚より薄い薄肉部５ｂ（ツバ部分）を有すると共に、該薄肉部５ｂの裏側に円形又は多角形のザグリ溝５が形成されている。例えば、小径穴４の大きさは約ｄ１＝１〜２mmである。また、前記小径穴４の裏側周囲に形成するザグリ溝５の大きさは、約ｄ２＝２〜３mmであり、そのザグリ溝５上部のツバ部分（薄肉部）の厚みｈは、金属母材２の厚さｔに対して、ｔ／２≦ｈ≦ｔ／３程度にするとよい。また、ザグリ溝５の形状は、円形だけでなく、図４に示すように多角形にしてもよい。
【００２０】
図５，図６及び図７は、封止栓の形状を示す平面図及び断面図である。すなわち、小径穴４に挿入する封止栓３の頭部には、短時間で溶融可能な大きさの薄肉を有する張り出し部３ａを設けている。張り出し部３ａは、円形だけでなく、多角形にすることもできる。例えば、図５に示した封止栓３の頭部は、加工が簡単な円形の平面形状をしており、また、図６に示した封止栓の頭部は、外形が円形で上面が滑らかな曲面形状又は半球形状をしている。さらに、図７に示した封止栓３の頭部は、外形が多角形で上面が平面形状をしている。この上面を滑らかな曲面形状にしてもよい。
【００２１】
これらの封止栓３頭部に設ける円形又は多角形の張り出し部３ａは、少なくとも小径穴４の内径ｄ１より大きく、ザグリ溝５の内径ｄ２より小さい外径（ｄ１＜Ｄ＜ｄ２）にし、ザグリ溝５上部の薄肉部５ｂの体積（小径穴を含む合計体積：ｄ２＊ｄ２＊π＊ｈ／４）と同程度又は幾分小さい体積に形成するとよい。封止栓３の張り出し部を多角形にすると、転がりにくくつかみ易く、体積の調整も容易である。また、小径穴４に挿入する挿入部３ｂは、小径穴の内径ｄ１とほぼ同じ寸法にし、圧入や押し圧によって小径穴にカシメ密着できるようにするとよい。上述の封止栓３及び小径穴を有する金属母材２は、例えば、金型成形加工によって容易に製作することが可能である。また、封止栓３及び小径穴を有する金属母材２の材質は、いずれも軽量なアルミニウムやアルミニウム合金である。金属母材２に安価なスチール材又は耐食性に優れたステンレス材を用いる場合には、溶接性を良くするために、封止栓３の材料も前記金属板と同じ材質又は類似の材質を用いることが好ましい。
【００２２】
このように、封止栓３頭部に短時間で溶融可能な円形又は多角形の張り出し部３ａを設けると、封止栓３の張り出し部３ａを治具などで簡単につかんで小径穴４へ圧入することができ、張り出し部３ａの下面と小径穴４周囲の金属母材の表面とを確実に密着させることができるばかりでなく、金属母材の板表面より凸形状に突き出した封止栓３頭部にアーク熱源を加え易くなる。また、円形又は多角形のザグリ溝５を金属母材２の裏面側に設けると、封止溶接すべき小径穴４周辺部の肉厚が薄く、表面側から行うアーク溶接で裏側まで完全に溶融させることができる。また、張り出し部３ａの体積を薄肉部５ｂの体積と同程度又は幾分小さい体積に形成すると、融合すべき薄肉部５ｂとの体積バランスが良くなり、短時間で封止栓３頭部を確実に溶融でき、小径穴４周辺の薄肉部５ｂと平滑に一体融合させることができる。
【００２３】
図８は、本発明の封止溶接法による小径穴の封止をＴＩＧアーク溶接によって行う工程を示す断面図及び溶接電流と時間との関係を示す線図であり、（１）溶接前の封止栓と電極の配置、（２）封止栓頭部のアーク加熱、（３）封止栓頭部の球形溶融、（４）金属母材の薄肉部との一体融合、（５）溶接後の封止溶接部、（６）時間経過の電流波形の様子をそれぞれ示している。この実施例で用いているアーク熱源は、非消耗性のタングステンを電極１２にするＴＩＧアークであり、所定の溶接条件（電流と溶接時間）を溶接電源に設定し出力させている。
【００２４】
すなわち、図８の（１）に示すように、金属母材２の裏側にザグリ溝５を有する小径穴４に密着挿入された封止栓３の頭部中央に電極１２先端を位置決めする。溶接開始によってシールドガス（Ａｒガス）流出の雰囲気内で封止栓３頭部にアーク１１を発生させ、図８の（６）に示すように所定時間Ｔ（ｍｓ）の電流Ｉ（Ａ）を出力させている。次に、図８の（２）に示すようにアーク加熱によって封止栓３頭部の張り出し部３ａが最初に溶融し、図８の（３）に示すように、溶融金属の表面張力によって球形状に溶融変化する。そして、図８の（４）に示すように、その後に加熱溶融される小径穴４周辺の薄肉部５ｂと、既に球形状に溶融変化した封止栓３頭部の張り出し部３ａとが平滑に一体融合し、金属母材２の裏側まで完全に溶け込ますことができる。更に、図８の（５）に示すように溶接後の表面が平滑で略円形を有する完全封止の良好な溶接部９を得ることができる。例えば、アルミニウム材で、小径穴４の径ｄ１が１.４mm 、ザグリ溝５の径ｄ２が２.４mm 、ツバ部分の厚みｈが約０.３mm の場合、電流Ｉが９０Ａの時で約２９ｍｓの時間、４０Ａの時で約１００ｍｓの時間でアーク溶接すると、それぞれ良好な溶接部９を得ることができる。
【００２５】
接合良好な適正条件は、電流Ｉ（Ａ）と時間Ｔ（ｍｓ）との相関関係があり、下記の（１）式で求めることができる。ただし、ｂは、小径穴４接合部分の溶融に係わる乗数であり、封止栓３及び金属母材２，小径穴４周辺部の形状や材質などの違いで変化し、０.５〜０.８程度となる。ｃは、栓頭部の加熱に係わる定数であり、約９３００〜１７５０００の範囲である。
【００２６】
Ｉ＝(ｃ／Ｔ)^b …（１）
このように、所定条件のアーク熱源を封止栓３の頭部より短時間与えて加熱溶融させると、封止栓３の張り出し部３ａと金属母材２表面の小径穴４周辺部とが適正に一体融合し完全封止することができ、従来のレーザー溶接による円周封止溶接と異なる融合形態及び溶け込み形状になり、溶接後の表面が平滑で高品質な溶接部を得ることができる。また、溶接条件を少なくとも電流と溶接時間との関係式に基づいて設定すると、完全封止が可能な適正条件を確実に出力でき、溶接条件の管理，溶接の品質管理が容易となる。また、アルミニウム材と異なる他のステンレス材やスチール材やニッケル材などの金属材料に対しても、図８に示したＴＩＧアーク溶接によって良好に穴封止溶接を行うことが可能である。これらの金属材料は、アルミニウム材より融点が高いが、電気抵抗が大きいためにTIGアークによる通電加熱で溶融し易い材料である。
【００２７】
図９は、本発明の封止溶接法の工程を示すフロー図である。最初に、別の工程で製造組立２１された金属母材を次の栓挿入工程２２に搬送する。栓挿入工程２２で金属母材の表面にある小径穴４に封止栓３を封止栓挿入装置３１により圧入２７する。次に、栓圧入後の金属母材２を母材搬入搬出装置３２により次の溶接工程２５に搬入する。溶接工程２５に搬送された金属母材を所定位置に配置し、非消耗性電極による溶接トーチ１３をトーチ可動及び位置決め装置３３により封止栓３の上部中央位置に移動及び位置決め２４する。そして、溶接電源３５及び溶接トーチ１３からアーク熱源を封止栓３頭部に与えて小径穴４の封止溶接を行う。この封止溶接の終了後に、母材搬入搬出装置３２により金属母材２を搬出する。最後に、品質検査工程２７に配備している品質検査装置によって、溶接箇所の拡大画像をモニタ画面に表示及び観察し、溶接欠陥の有無，品質の良否を判定できるようにしている。
【００２８】
このように構成することにより、小物容器の蓋板又は平板である金属母材の搬送から小径穴の封止溶接及び溶接後に搬出するまでの一連動作を自動で繰返し実行でき、封止溶接の対象製品を確実に量産することができる。さらに、前記溶接工程又は搬出工程の後に品質検査工程を設けて金属母材の封止溶接部の良否を検査することにより、不良品の有無を判定して合格品のみを選択，認定し、品質の良いものを供給できると共に、不良率の低減対策にも活用することが可能である。
【００２９】
図１０は、本発明の自動溶接装置の一実施形態を示す構成図である。母材搬入搬出装置３２は、搬送治具３０中に予め設置されている溶接対象製品の金属母材２を溶接場所の位置に搬入し、封止溶接の終了後に搬出させるための装置である。トーチ可動及び位置決め装置３３は、封止溶接すべき小径穴に前工程で挿入（圧入）されている封止栓３の上部中央位置に非消耗性電極による溶接トーチ１３を移動及び位置決めするものである。溶接電源３５は、所望の溶接条件（電流と時間）が設定でき、予め設定された適正溶接条件を制御盤３８からの指令で出力し、溶接トーチ１３と金属母材２との間にアーク熱源を供給する。この溶接電源３５と溶接トーチ１３，金属母材２（搬送治具３０に設置）との間に給電ケーブル１５ａ，１５ｂが接続されている。ガスボンベ１４は、不活性ガスのＡｒガスであり、溶接電源に接続されており、アーク溶接部を保護するために所定流量のＡｒガスがトーチケーブル１６を経由して溶接トーチ１３先端より流出するようになっている。また、電流検出器３６は、アーク溶接（小径穴の封止溶接）で出力される電流値を検出するものであり、この電流検出器３６によって小径穴４の封止溶接が正常で確実に実行されたかどうかを監視することができる。また、溶接回数カウント器３７は、前記小径穴の封止溶接の繰返し回数が指定及び表示でき、予め指定された回数によって繰返しの実行回数をカウント（検知）し、そのカウント結果や終了した結果を制御盤３８に適宜送信するようにしている。制御盤３８は、構成機器を統括して管理及び制御するものであり、溶接対象製品の金属母材２の搬入と溶接終了後の搬出とを母材搬入搬出装置３２に実行させ、溶接トーチ１３の位置決めをトーチ可動及び位置決め装置３３に実行させ、小径穴の封止溶接を溶接電源に実行させるようにしている。
【００３０】
溶接トーチ交換装置３４は、予備の溶接トーチを数本装備しており、アーク溶接の繰返し使用によって消耗した電極１２を新しい電極に交換するため、予備の溶接トーチと自動交換するものである。特に、予め指定回数の封止溶接が終了した時に溶接動作を一時停止し、溶接トーチ１３をトーチ交換装置３４によって予備の溶接トーチに自動交換させるようにするとよい。また、外乱などにより電極１２が損傷したり、著しく消耗した場合には、割込み操作をして予備の溶接トーチに自動交換させることも可能である。一方、上述のトーチ交換装置３４の代わりに電極交換装置を設けて、溶接トーチ１３内の電極１２(タングステン電極棒)のみを自動交換するようにしてもよい。この電極交換装置を設ける場合には、溶接トーチ１３内のタングステン電極棒が脱着可能な構造を有する公知技術の溶接トーチ１３を使用するとよい。
【００３１】
溶接対象製品の金属母材２は、小径穴の封止溶接が終了する毎に、母材搬入搬出装置３２によって溶接工程から搬出され、図９に示した次の品質検査工程に移行される。この品質検査工程には、品質検査装置３９が配備されており、封止溶接部の品質検査を行うようにしている。
【００３２】
このように構成することにより、量産対応の自動溶接設備が実現でき、溶接対象製品の金属母材の搬入から小径穴の封止溶接及び溶接後の搬出まで一連の溶接動作を自動で繰返し実行することができる。また、アーク溶接の繰返し使用によって消耗した電極を短時間で新しい電極又は新しい電極を配備している溶接トーチに短時間で自動交換することができる。また、この自動交換による一時停止の時間短縮，繰返し使用回数の設定と管理，装置稼働時間率の管理，安定なアーク溶接の再現，溶接品質の保持を容易にすることができる。さらに、品質検査装置によって量産対応の溶接品質の検査が可能になり、不良品の有無を判定して合格品のみを選択，認定し、品質の良いものを供給することができる。
【００３３】
【発明の効果】
本発明によれば、小径穴を短時間で少ないエネルギーで容易に溶接して確実に完全封止でき、溶接後の表面が平滑で高品質な溶接部を得ることができる。また、溶接動作を確実に繰返し実行し、再現性及び量産性の高い封止溶接法及びその自動溶接装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の封止溶接法に係わる小物容器の斜視図である。
【図２】小径穴を有する平板の金属母材を示す上面図である。
【図３】本発明の封止溶接法に係わる小径穴の形状及びこの小径穴に挿入する封止栓の一実施形態を示す断面図及び平面図である。
【図４】図３に示した小径穴と異なる小径穴周辺部の形状を示す断面図及び平面図である。
【図５】本発明の封止溶接法に係わる封止栓頭部の形状の一実施形態を示す断面図及び平面図である。
【図６】図５に示した封止栓頭部と異なる封止栓頭部の形状を示す断面図及び平面図である。
【図７】図６に示した封止栓頭部と異なる他の封止栓頭部の形状を示す断面図及び平面図である。
【図８】本発明の封止溶接法による小径穴の封止をＴＩＧアーク溶接によって行う工程を示す断面図及び溶接電流と時間との関係を示す線図である。
【図９】本発明の封止溶接法の工程を示すフロー図である。
【図１０】本発明の自動溶接装置の一実施形態を示す構成図である。
【符号の説明】
１…小物容器、２…金属母材、３…封止栓、３ａ…張り出し部、３ｂ…挿入部、４…小径穴、５…ザグリ溝、５ｂ…薄肉部、９…溶接部、１１…アーク、１２…電極、１３…溶接トーチ、１４…ガスボンベ、１５ａ，１５ｂ…給電ケーブル、１６…トーチケーブル、３０…搬送治具、３１…封止栓挿入装置、３２…母材搬入搬出装置、３３…トーチ可動位置決め装置、３４…トーチ交換装置、３５…溶接電源、３６…電流検出器、３７…溶接回数カウント器、３８…制御盤。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealing welding method for a small-diameter hole provided on the surface of a metal base material that is a lid plate or a flat plate of a small container, and an automatic welding apparatus thereof.
[0002]
[Prior art]
There are several conventional techniques for sealing and welding a small-diameter hole provided on the surface of a metal container. For example, in the sealed battery of Patent Document 1, after injecting an electrolytic solution, it is proposed that a spherical sealing plug made of aluminum is pressed into a small-diameter hole and sealed by ultrasonic welding. Further, in the rectangular sealed storage battery of Patent Document 2 and the manufacturing method thereof, and the sealed battery of Patent Document 3, it has been proposed to insert a sealing plug into a small-diameter hole and seal it by laser welding. In addition, in the sealing method and the sealed container in the container of Patent Document 4, a spherical sealing member made of stainless steel is pushed into the inlet, and sealing welding is performed in two stages of resistance welding and laser welding with different means. Has been proposed.
[0003]
[Patent Document 1]
JP-A-8-45488 (Claims)
[Patent Document 2]
Japanese Patent Laid-Open No. 11-25936 (Claims)
[Patent Document 3]
JP-A-11-149915 (Claims)
[Patent Document 4]
JP 2002-239762 A (Claims)
[0004]
[Problems to be solved by the invention]
Each of Patent Documents 1 to 4 is shallow penetration circumferential welding in which only the joint between the outer periphery of the sealing plug and the cover plate surface is melted by ultrasonic welding, laser welding, or the like. In order to suppress crevice corrosion and strength reduction, it is better not to leave an unjoined part at the joint on the back side. Further, if a gap is generated in the joint portion or a solution adheres to the injection hole portion, the formation of the weld bead is likely to be disturbed, and an unjoined portion is likely to be generated due to the generation of the pinhole.
[0005]
The object of the present invention is to be able to weld a small-diameter hole on the surface of a metal base material, which is a lid plate or a flat plate of a small container, easily and in a short time, to ensure complete sealing, and to have a smooth and high-quality surface after welding. An object of the present invention is to provide a small-diameter hole sealing welding method and an automatic welding apparatus thereof capable of obtaining a welded portion.
[0006]
[Means for Solving the Problems]
The present invention relates to a sealing welding method in which a sealing plug is inserted into a small-diameter hole provided on the surface of a metal base material that is a lid plate or a flat plate of a small container, and the small-diameter hole is sealed. On the back side, a thin-walled portion having a circular shape or a polygonal shape in the vicinity of the small-diameter hole is formed on the back surface, and a protruding portion having a circular or polygonal shape with an outer diameter larger than the inner diameter of the small-diameter hole is formed on the head of the sealing plug. After forming and inserting the sealing plug into the small-diameter hole, the sealing plug and the thin portion of the metal base material are melted and sealed and welded by an arc heat source.
[0007]
Further, in the sealing welding method described above, the insertion step of inserting the sealing plug into the small-diameter hole of the metal base material, the metal base material after the plug insertion is carried into the welding step, and placed at a predetermined position, A positioning step of moving and positioning a welding torch by a consumable electrode to the upper center position of the sealing plug, and welding for sealing and welding the small diameter hole by applying an arc heat source from the welding torch to the head of the sealing plug A step and an unloading step of unloading the metal base material after the sealing welding are sequentially performed. Furthermore, a quality inspection step may be provided after the welding step or the unloading step to inspect the quality of the sealed welded portion of the metal base material.
[0008]
The automatic welding apparatus of the present invention includes a plug insertion device that inserts a sealing plug into a small-diameter hole of a metal base material, and a base material carry-in that carries the metal base material after the plug is inserted into a welding process and after completion of welding. An unloading device; a torch positioning device that disposes the metal base material at a predetermined position; and moves and positions a welding torch by a non-consumable electrode to an upper center position of the sealing plug; the welding torch and the metal base material; A welding power source for supplying an arc heat source under a predetermined welding condition, a base material carrying-in / out device, a torch positioning device, and a control panel for managing and controlling the welding power source.
[0009]
Further, in the above automatic welding apparatus, a torch exchange apparatus for automatically exchanging the welding torch, an electrode exchange apparatus for automatically exchanging a tungsten electrode rod in the welding torch, and a frequency counting apparatus for setting the number of repetitions of the sealing welding, The welding operation is temporarily stopped when a predetermined number of sealed weldings are completed in advance, and the welding torch is automatically replaced by a torch changing device, or the tungsten electrode rod in the welding torch is automatically changed by an electrode changing device. The welding operation is replaced, and the welding operation is restarted after the replacement is completed. It is more preferable to provide a welding inspection device for inspecting the quality of the sealed welded portion every time the metal base material after welding is carried out.
[0010]
That is, according to the present invention, the sealing plug and the thin-walled portion can be integrally melted by arc heating in a short time, and a hole-sealed welded portion with very little variation in the melting range can be obtained with less energy.
[0011]
In particular, by forming in advance a circular or polygonal overhanging part that can be melted in a short time on the head of the sealing plug, the head of the sealing plug can be easily grasped with a jig and pressed into a small-diameter hole. In addition to ensuring that the lower surface of the overhanging portion and the upper surface around the small-diameter hole are in close contact with each other, it is easy to add an arc heat source to the plug head protruding from the surface height of the metal base material, By heating and melting, a welded portion having a smooth surface after welding and a high quality can be obtained.
[0012]
The arc heat source is TIG arc welding with a non-consumable electrode, and the welding conditions by the arc welding are set and output to a welding power source based on a relational expression between current I (A) and welding time T (ms). As a result, not only can sealing sealing be performed reliably under appropriate energy conditions, but also management of welding conditions and welding quality becomes easy.
[0013]
Also, an insertion step of inserting the sealing plug into the small-diameter hole of the metal base material, and the metal base material after the plug insertion is carried into the welding step and arranged at a predetermined position, and a welding torch with a non-consumable electrode is provided A positioning step of moving and positioning to the upper center position of the sealing plug, a welding step of sealingly welding the small-diameter hole by giving an arc heat source from the head of the sealing plug from the welding torch, and after the sealing welding By sequentially executing the unloading step of unloading the metal base material, a series of operations from the transportation of the metal base material, which is a cover plate or a flat plate of a small container, to the small-diameter hole sealing welding and unloading after welding are automatically performed. It can be executed repeatedly, and the target product for sealing welding can be reliably mass-produced.
[0014]
In addition, a quality inspection step is provided after the welding step or the unloading step to check the quality of the sealed welded portion of the metal base material. It is possible to supply products with good quality and also to take measures for reducing the defect rate.
[0015]
Further, according to the automatic welding apparatus of the present invention, automatic welding equipment for mass production can be realized, and a series of welding operations are automatically performed from conveyance of a metal base material of a target product to sealing welding of a small-diameter hole and unloading after welding. Can be executed repeatedly.
[0016]
Further, by further providing a torch changing device for automatically changing the welding torch or an electrode changing device for automatically changing the tungsten electrode rod in the welding torch, and a number counting device for setting the number of repetitions of the sealing welding, arc welding is further provided. It is possible to automatically replace a worn electrode by repeated use with a new electrode or a welding torch having a new electrode in a short time. In particular, the welding operation is temporarily stopped when a predetermined number of sealed weldings have been completed in advance, and the welding torch is automatically replaced by a torch changing device, or the tungsten electrode rod in the welding torch is automatically changed by an electrode changing device. After completion of the replacement, the operation of the welding line and sealing welding is resumed, thereby shortening the suspension time, setting and managing the number of repeated use, managing the equipment operating time rate, reproducing stable arc welding, welding Quality can be easily maintained.
[0017]
Furthermore, by providing a welding inspection device that inspects the quality of the sealed welded portion every time the metal base material after welding is carried out, quality inspection for mass production becomes possible, and the presence or absence of defective products is determined. Only qualified products can be selected and certified, and quality products can be supplied.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view of a small container related to the sealing welding method of the present invention. A small-diameter hole 4 is provided on the surface of the metal base material 2 at the top of the small container 1. A sealing plug 3 is inserted into the small diameter hole 4 and sealed and welded. FIG. 2 is a top view showing a flat metal base material 2 having a small-diameter hole 4.
[0019]
FIG. 3 is a cross-sectional view showing an embodiment of a small-diameter hole related to the sealing welding method of the present invention and an embodiment of a sealing plug inserted into the small-diameter hole. FIG. 4 is a cross-sectional view and a plan view in which the shape of a counterbore groove formed in the outer peripheral portion of the small-diameter hole is different. That is, as shown in FIG. 3, the outer peripheral portion of the small-diameter hole 4 has a thin portion 5b (head portion) thinner than the thickness of the metal base material 2, and a circular or polygonal counterbore on the back side of the thin portion 5b. A groove 5 is formed. For example, the size of the small-diameter hole 4 is about d1 = 1 to 2 mm. Further, the size of the counterbore groove 5 formed around the back side of the small-diameter hole 4 is about d2 = 2 to 3 mm, and the thickness h of the brim portion (thin wall portion) on the upper part of the counterbore groove 5 is the metal base material 2. The thickness t is preferably about t / 2 ≦ h ≦ t / 3. Further, the shape of the counterbore groove 5 is not limited to a circle, but may be a polygon as shown in FIG.
[0020]
5, 6 and 7 are a plan view and a cross-sectional view showing the shape of the sealing plug. That is, the head portion of the sealing plug 3 inserted into the small-diameter hole 4 is provided with an overhang portion 3a having a thin wall size that can be melted in a short time. The overhang portion 3a can be not only circular but also polygonal. For example, the head of the sealing plug 3 shown in FIG. 5 has a circular planar shape that is easy to process, and the head of the sealing plug shown in FIG. It has a smooth curved surface shape or hemispherical shape. Furthermore, the head of the sealing plug 3 shown in FIG. 7 has a polygonal outer shape and a planar shape on the upper surface. You may make this upper surface into a smooth curved surface shape.
[0021]
The circular or polygonal protruding portion 3a provided on the head of these sealing plugs 3 has an outer diameter (d1 <D <d2) that is at least larger than the inner diameter d1 of the small-diameter hole 4 and smaller than the inner diameter d2 of the counterbored groove 5. The volume may be the same as or slightly smaller than the volume of the thin portion 5b above the groove 5 (total volume including small diameter holes: d2 * d2 * π * h / 4). If the protruding portion of the sealing plug 3 is polygonal, it is difficult to roll and it is easy to grasp, and the volume can be adjusted easily. The insertion portion 3b to be inserted into the small-diameter hole 4 is preferably approximately the same size as the inner diameter d1 of the small-diameter hole so that it can be caulked closely to the small-diameter hole by press-fitting or pressing. The metal base material 2 having the sealing plug 3 and the small-diameter hole described above can be easily manufactured by, for example, a mold forming process. Moreover, the material of the metal base material 2 which has the sealing plug 3 and a small diameter hole is all lightweight aluminum and aluminum alloy. When using an inexpensive steel material or a stainless steel material with excellent corrosion resistance for the metal base material 2, the material of the sealing plug 3 should be the same as or similar to the metal plate in order to improve the weldability. Is preferred.
[0022]
As described above, when the circular or polygonal overhanging portion 3a that can be melted in a short time is provided at the head of the sealing plug 3, the overhanging portion 3a of the sealing plug 3 can be easily grasped with a jig or the like into the small-diameter hole 4. Sealing plug that can be press-fitted and not only allows the lower surface of the overhanging portion 3a and the surface of the metal base material around the small-diameter hole 4 to be in close contact with each other, but also protrudes in a convex shape from the plate surface of the metal base material It becomes easy to add an arc heat source to the three heads. In addition, when a circular or polygonal counterbore groove 5 is provided on the back side of the metal base material 2, the peripheral portion of the small-diameter hole 4 to be sealed and welded is thin, and it is completely melted to the back side by arc welding performed from the front side. Can be made. Moreover, if the volume of the overhanging portion 3a is formed to be the same as or slightly smaller than the volume of the thin portion 5b, the volume balance with the thin portion 5b to be fused is improved, and the head of the sealing plug 3 can be secured in a short time. And can be integrally and smoothly integrated with the thin portion 5b around the small-diameter hole 4.
[0023]
FIG. 8 is a cross-sectional view showing a process of sealing a small-diameter hole by the sealing welding method of the present invention by TIG arc welding and a diagram showing the relationship between welding current and time. (1) Sealing before welding Stopper and electrode arrangement, (2) Arc heating of sealing plug head, (3) Spherical melting of sealing plug head, (4) Integrated fusion with thin part of metal base material, (5) After welding (6) The state of the current waveform over time is shown. The arc heat source used in this embodiment is a TIG arc in which non-consumable tungsten is used as the electrode 12, and predetermined welding conditions (current and welding time) are set in a welding power source and output.
[0024]
That is, as shown in FIG. 8 (1), the tip of the electrode 12 is positioned at the center of the head of the sealing plug 3 that is tightly inserted into the small-diameter hole 4 having the counterbored groove 5 on the back side of the metal base material 2. When welding starts, an arc 11 is generated at the head of the sealing plug 3 in an atmosphere of shielding gas (Ar gas) outflow, and a current I (A) for a predetermined time T (ms) is generated as shown in FIG. 8 (6). It is output. Next, as shown in (2) of FIG. 8, the overhanging portion 3a of the head portion of the sealing plug 3 is first melted by arc heating, and as shown in (3) of FIG. Melt to shape. Then, as shown in FIG. 8 (4), the thin-walled portion 5b around the small-diameter hole 4 to be heated and melted thereafter and the overhanging portion 3a of the sealing plug 3 head already melted and changed into a spherical shape are smooth. It can be fused together and completely melted to the back side of the metal base 2. Furthermore, as shown in (5) of FIG. 8, the welded portion 9 having a perfectly sealed surface having a smooth surface after welding and a substantially circular shape can be obtained. For example, when the diameter d1 of the small-diameter hole 4 is 1.4 mm, the diameter d2 of the counterbored groove 5 is 2.4 mm, and the thickness h of the flange portion is about 0.3 mm, about 29 ms when the current I is 90 A. When the arc welding is performed for about 100 ms at the time of 40 A, good welds 9 can be obtained respectively.
[0025]
An appropriate condition for good bonding has a correlation between the current I (A) and the time T (ms), and can be obtained by the following equation (1). However, b is a multiplier relating to the melting of the joint portion of the small diameter hole 4 and varies depending on the shape and material of the sealing plug 3, the metal base material 2, and the peripheral portion of the small diameter hole 4, and is 0.5 to 0.5. It will be about 8. c is a constant related to the heating of the plug head, and is in the range of about 9300 to 175000.
[0026]
I = (c / T) ^b (1)
Thus, when an arc heat source of a predetermined condition is given from the head of the sealing plug 3 for a short time and heated and melted, the overhanging portion 3a of the sealing plug 3 and the peripheral portion of the small-diameter hole 4 on the surface of the metal base material 2 are appropriate. Can be integrated and completely sealed, resulting in a fusion form and penetration shape different from the conventional circumferential welding by laser welding, and a welded portion having a smooth surface after welding and a high quality can be obtained. Moreover, if the welding conditions are set based on at least the relational expression between the current and the welding time, the proper conditions capable of complete sealing can be reliably output, and the management of the welding conditions and the quality control of the welding are facilitated. In addition, hole sealing welding can be favorably performed by TIG arc welding shown in FIG. 8 for other stainless steel materials different from aluminum materials, such as steel materials and nickel materials. These metal materials have higher melting points than aluminum materials, but are easily meltable by energization heating with a TIG arc because of their large electric resistance.
[0027]
FIG. 9 is a flowchart showing the steps of the sealing welding method of the present invention. First, the metal base material manufactured and assembled 21 in another process is transferred to the next plug insertion process 22. In the plug insertion step 22, the sealing plug 3 is press-fitted 27 into the small diameter hole 4 on the surface of the metal base material by the sealing plug insertion device 31. Next, the metal base material 2 after the plug press-fitting is carried into the next welding process 25 by the base material carry-in / out device 32. The metal base material transported to the welding process 25 is placed at a predetermined position, and the welding torch 13 with the non-consumable electrode is moved and positioned 24 to the upper central position of the sealing plug 3 by the torch movable and positioning device 33. Then, an arc heat source is applied to the head of the sealing plug 3 from the welding power source 35 and the welding torch 13 to perform sealing welding of the small diameter hole 4. After this sealing welding is completed, the metal base material 2 is carried out by the base material carry-in / out device 32. Finally, an enlarged image of the welded part is displayed and observed on a monitor screen by a quality inspection device provided in the quality inspection step 27 so that the presence or absence of welding defects and quality can be determined.
[0028]
By configuring in this way, a series of operations from the conveyance of a metal base material, which is a cover plate or a flat plate of a small container, to sealing welding of a small-diameter hole and unloading after welding can be automatically and repeatedly performed. The product can be mass-produced reliably. In addition, a quality inspection step is provided after the welding step or the unloading step to check the quality of the sealed welded portion of the metal base material. It is possible to supply products with good quality and also to take measures for reducing the defect rate.
[0029]
FIG. 10 is a block diagram showing an embodiment of the automatic welding apparatus of the present invention. The base material carry-in / out device 32 is a device for carrying in the metal base material 2 of the product to be welded that is installed in advance in the carrying jig 30 to the position of the welding place and carrying it out after the end of the sealing welding. The torch movable and positioning device 33 moves and positions the welding torch 13 by a non-consumable electrode at the upper center position of the sealing plug 3 inserted (press-fitted) into the small diameter hole to be sealed and welded in the previous process. is there. The welding power source 35 can set desired welding conditions (current and time), outputs preset appropriate welding conditions in response to a command from the control panel 38, and generates an arc heat source between the welding torch 13 and the metal base material 2. Supply. Power feeding cables 15 a and 15 b are connected between the welding power source 35, the welding torch 13, and the metal base material 2 (installed on the conveying jig 30). The gas cylinder 14 is an inert gas Ar gas and is connected to a welding power source so that a predetermined flow rate of Ar gas flows out from the tip of the welding torch 13 via the torch cable 16 in order to protect the arc welding portion. It has become. The current detector 36 detects a current value output by arc welding (sealing welding of a small diameter hole), and the current detector 36 performs normal and reliable sealing welding of the small diameter hole 4. Can be monitored. Further, the welding number counter 37 can designate and display the number of repetitions of sealing welding of the small-diameter hole, and count (detect) the number of repetitions according to the number of times designated in advance. The information is appropriately transmitted to the control panel 38. The control panel 38 controls and controls the component devices in an integrated manner. The control panel 38 causes the base material carry-in / out device 32 to carry in the metal base material 2 of the product to be welded and carry out the welding after completion of welding. The positioning is performed by the torch movable and positioning device 33 so that the welding power source executes sealing welding of the small-diameter hole.
[0030]
The welding torch exchanging device 34 is equipped with several spare welding torches, and automatically exchanges with a spare welding torch in order to replace the electrode 12 consumed by repeated use of arc welding with a new electrode. In particular, it is preferable that the welding operation is temporarily stopped when a predetermined number of sealed weldings are completed in advance, and the welding torch 13 is automatically replaced with a spare welding torch by the torch replacing device 34. Further, when the electrode 12 is damaged due to a disturbance or the like or is significantly consumed, an interruption operation can be performed to automatically replace the spare welding torch. On the other hand, an electrode exchange device may be provided instead of the above-described torch exchange device 34 so that only the electrode 12 (tungsten electrode rod) in the welding torch 13 is automatically exchanged. When this electrode exchange device is provided, a well-known welding torch 13 having a structure in which the tungsten electrode rod in the welding torch 13 is detachable may be used.
[0031]
The metal base material 2 of the product to be welded is carried out of the welding process by the base material carry-in / out device 32 every time sealing welding of the small-diameter hole is completed, and is transferred to the next quality inspection process shown in FIG. In this quality inspection process, a quality inspection device 39 is provided to inspect the quality of the sealed welded portion.
[0032]
By configuring in this way, automatic welding equipment for mass production can be realized, and a series of welding operations are automatically and repeatedly performed from carrying in the metal base material of the product to be welded to sealing welding of small diameter holes and carrying out after welding. be able to. In addition, an electrode consumed due to repeated use of arc welding can be automatically replaced in a short time with a new electrode or a welding torch equipped with a new electrode. In addition, it is possible to easily shorten the suspension time by this automatic replacement, set and manage the number of repeated use, manage the apparatus operating time rate, reproduce stable arc welding, and maintain the welding quality. Furthermore, it is possible to inspect the welding quality for mass production by the quality inspection device, determine the presence or absence of defective products, select and certify only acceptable products, and supply high quality products.
[0033]
【The invention's effect】
According to the present invention, a small-diameter hole can be easily welded with a small amount of energy and can be completely sealed reliably, and a welded portion having a smooth surface after welding and a high quality can be obtained. In addition, it is possible to provide a sealing welding method and an automatic welding apparatus for the same that repeatedly perform the welding operation reliably and have high reproducibility and mass productivity.
[Brief description of the drawings]
FIG. 1 is a perspective view of a small container according to the sealing welding method of the present invention.
FIG. 2 is a top view showing a flat metal base material having a small-diameter hole.
FIGS. 3A and 3B are a cross-sectional view and a plan view showing an embodiment of a small-diameter hole and a sealing plug inserted into the small-diameter hole according to the seal welding method of the present invention. FIGS.
4 is a cross-sectional view and a plan view showing a shape of a peripheral portion of a small-diameter hole different from the small-diameter hole shown in FIG.
FIGS. 5A and 5B are a sectional view and a plan view showing an embodiment of the shape of a sealing plug head according to the sealing welding method of the present invention. FIGS.
6 is a cross-sectional view and a plan view showing a shape of a sealing plug head different from the sealing plug head shown in FIG. 5. FIG.
7 is a cross-sectional view and a plan view showing the shape of another sealing plug head different from the sealing plug head shown in FIG. 6;
FIG. 8 is a cross-sectional view showing a process of sealing a small-diameter hole by the sealing welding method of the present invention by TIG arc welding, and a diagram showing the relationship between welding current and time.
FIG. 9 is a flowchart showing the steps of the sealing welding method of the present invention.
FIG. 10 is a configuration diagram showing an embodiment of the automatic welding apparatus of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Small container, 2 ... Metal base material, 3 ... Seal plug, 3a ... Overhang | projection part, 3b ... Insertion part, 4 ... Small-diameter hole, 5 ... Counterbore groove, 5b ... Thin wall part, 9 ... Welding part, 11 ... Arc , 12 ... Electrode, 13 ... Welding torch, 14 ... Gas cylinder, 15a, 15b ... Feeding cable, 16 ... Torch cable, 30 ... Transfer jig, 31 ... Seal plug insertion device, 32 ... Base material loading / unloading device, 33 ... Torch movable positioning device, 34... Torch exchange device, 35 .. welding power source, 36... Current detector, 37.

Claims

A sealing welding method for small-diameter holes in which a sealing plug with an overhang is inserted into a small-diameter hole provided on the surface of a metal base material that is a lid plate or a flat plate of a container, and the small-diameter hole is sealed by welding with an arc heat source. In
The head portion of the sealing plug with the overhanging portion has a thin wall portion thinner than the thickness of the metal base material on the front peripheral portion of the small diameter hole, and a circular or polygonal counterbore groove is formed on the back side of the thin wall portion. The portion is formed with a protruding portion having an outer diameter larger than the inner diameter of the small-diameter hole and having a circular or polygonal shape, and after the sealing plug with the protruding portion is inserted into the small-diameter hole, the sealing plug A small-diameter hole sealing welding method, wherein the head and the thin portion of the metal base material are melted by arc welding of a non-consumable electrode method , and the small-diameter hole is sealed and welded.

In the sealing welding method of the small diameter hole according to claim 1,
An insertion step of inserting the sealing plug with the overhang portion into the small-diameter hole of the metal base material;
Positioning step of bringing the metal base material after plug insertion into the welding process and placing it at a predetermined position, and moving and positioning the non-consumable electrode type welding torch to the upper central position of the sealing plug with the overhanging portion;
Welding by applying an arc heat source from the welding torch to the head portion of the sealing plug with the overhang portion to melt the sealing plug head portion and the thin portion of the metal base material, and sealingly weld the small diameter hole. Process,
An unloading step of unloading the metal base material after the end of the sealing welding;
A sealing welding method for small-diameter holes, wherein a quality inspection step for inspecting the quality of the sealing weld portion of the metal base material is sequentially performed after the welding step or the unloading step.

Automatic that repeatedly performs sealing welding to seal the small-diameter hole by welding with an arc heat source by inserting a sealing plug with an overhanging portion into the small-diameter hole provided on the surface of the metal base material that is the lid plate or flat plate of the container A welding device,
The head portion of the sealing plug with the overhanging portion has a thin wall portion thinner than the thickness of the metal base material on the front peripheral portion of the small diameter hole, and a circular or polygonal counterbore groove is formed on the back side of the thin wall portion. In the part, an overhanging part having a circular or polygonal shape with an outer diameter larger than the inner diameter of the small diameter hole is formed,
A plug insertion device for inserting the sealing plug with the protruding portion into the small-diameter hole of the metal base material;
A base material carry-in / out device for carrying the metal base material after insertion of the stopper into the welding process and unloading after the end of welding;
A torch positioning device that places the metal base material after loading in a predetermined position, and moves and positions a non-consumable electrode type welding torch to an upper central position of the sealing plug with the overhanging portion;
A welding power source for supplying an arc heat source of a predetermined welding condition between the welding torch and the metal base material;
A control panel for managing and controlling the base material loading / unloading device, torch positioning device, welding power source;
With
Applying an arc heat source from the non-consumable electrode type welding torch to the head of the sealing plug with the overhanging portion to melt the sealing plug head and the thin portion of the metal base material, the small diameter hole An automatic welding apparatus characterized by sealing welding.

In the automatic welding apparatus according to claim 3,
A torch exchanging device for automatically exchanging the welding torch, an electrode exchanging device for automatically exchanging a tungsten electrode rod in the welding torch, and a welding number counter for designating and detecting the number of times of sealing welding the small diameter hole of the metal base material; A quality inspection device for inspecting the quality of the sealed welded portion every time the metal base material is carried out after the end of the sealed welding,
When it is detected that the number of times of sealing welding to be repeatedly performed has reached the number of times designated in advance in the welding number counter, the operation of sealing welding is temporarily stopped, and the welding torch is automatically operated by a torch changing device. Exchange or automatically replace the tungsten electrode rod in the welding torch with an electrode exchange device, and resume the operation of sealing welding the small-diameter hole and inspecting the sealed weld after welding after the replacement is completed. An automatic welding apparatus characterized by: