JP4764538B2

JP4764538B2 - Automatic welding method

Info

Publication number: JP4764538B2
Application number: JP2000118068A
Authority: JP
Inventors: 昭慈今永; 光明羽田; 昇斉藤; 正宏小林; 悦郎内山
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2000-04-19
Filing date: 2000-04-19
Publication date: 2011-09-07
Anticipated expiration: 2020-04-19
Also published as: JP2001300728A

Description

【０００１】
【発明の属する技術分野】
本発明は、溶接ワイヤを電極とするアーク溶接法に係り、特にアーク溶接の電流で生じるアーク磁気吹き現象を考慮して長尺部材に小物品部材を溶接する自動溶接方法に関する。
【０００２】
【従来の技術】
一般に溶接ワイヤを電極とするアーク溶接法は、非消耗性のタングステンを電極とするアーク溶接法と比べて、ワイヤ溶融速度が格段に速く、高能率であることから自動車部品、住宅建築部品、建設機械部品、昇降機部品などの組立て溶接に広く用いられている。しかし、直流アークやパルスアークの溶接では、電極と溶接母材との間に流れる溶接電流によって磁力線が生じ、その磁力線密度がアークの周辺で位置によって異なる場合や通電経路の変化によって磁力線密度がアークの周辺で位置によって変化する場合などに、アークが磁力によって偏向する磁気吹き現象が発生することや、このアークの偏向が溶接結果に悪影響を及ぼし易いことが知られている。
【０００３】
このため、直流電流やパルス電流の消耗電極式自動溶接装置を用いる組立て溶接現場では、従来からアークの磁気吹き現象を抑制する簡単な手段として、例えば、溶接母材の分散した複数の個所を部材側給電ケーブルで溶接電源と接続して通電経路を不特定に分散させ、溶接母材を流れる溶接電流を分散分流する方法が用いられている。また、溶接トーチの先端部又は溶接部分の近傍に電磁石などを配置して磁界をアーク及び溶融プールに与えて、アークの磁気吹きを防止する或いはアークや溶融プールを特定方向へ強制的に偏向させる方法が用いられることもある。なお、アーク磁気吹きが生じる現象やその現象をマグネットで抑制、方向制御する方法については、「アーク溶接現象：第４・３節アークの磁気吹き」（PP.１５３〜１６１、産報出版、安藤・長谷川著、昭和３７年７月１５日初版発行）に概略記載されている。
【０００４】
また、特開平７−３２１４６号公報には、磁気センサユニットをトーチ先端部に設けて、アーク溶接の電流で生じる磁界の強さ(磁力)と方向を検出及び表示する技術が開示されている。また、母材側に摺動給電するアーク電流用及びワイヤ電流用の摺動給電子をアーク溶接部近傍の溶接ヘッドに設けて、磁界変動によるアーク磁気吹きを防止する装置の例として、特開平８−１５５６４３号公報に記載の磁気吹き防止型溶接装置がある。また、溶融形成した溶融池に溶接線方向へ電流を流す(添加ワイヤに給電)と共にその直角方向に磁界(磁石設置)を与え、溶融池に開先底部方向へローレンツ力(磁力)を発生させながら溶接する一例として、特開平１０−９９９６６号公報に記載の上向・立向溶接方法がある。この他にも、電磁石を設置・利用する技術が幾つか提案されている。
【０００５】
【発明が解決しようとする課題】
溶接母材の分散した複数箇所を部材側給電ケーブルで溶接電源に接続して通電経路を不特定な経路に分散させ、溶接電流を分散分流することによって磁気吹きを抑制する従来法は、使用する部材側給電ケーブルの長さや太さ、長尺部材と小物品部材との大きさや導電率や接触状態、部材側給電ケーブルの接続位置や固定方法などの違いによって溶接電流の流れ方が変わるため、溶接電流を均等に分流させることが困難である。このため、上記従来方法では不特定で複雑な通電経路及び不安定な電流分散となって、アークの磁気吹き現象が突発的に不特定方向に発生して、アーク切れ、アークの乱れ、ワイヤ溶融の乱れ、ワイヤ溶滴移行時の溶滴飛散が生じ易くなり、アーク溶接現象の悪化、溶接欠陥の発生を招く恐れがある。
【０００６】
一方、前記特開平７−３２１４６号公報に記載のアーク溶接における磁気吹き検出方法及びその装置は、溶接電流で生じる磁界の強さ及び方向を検出するのに有効な手段であるが、アーク磁気吹き現象そのものを抑制、防止することはできない。しかも磁気センサユニットがトーチ先端部に設置されているために、アーク溶接による磁気センサユニットへの輻射熱の影響を緩和、抑制する構造にする必要があり、トーチ先端部が重装備になるばかりでなく、溶接時のトーチ操作性低下を招く恐れがある。
【０００７】
また、前記特開平８−１５５６４３号公報に記載の磁気吹き防止型溶接装置は、アーク電流及びワイヤ電流の母材通電経路をアーク溶接部近傍の特定位置に集中させることで、迷走電流及び磁界変動の防止、アーク磁気吹きの抑制に有効であると考えられる。しかし、アーク電流用及びワイヤ電流用の摺動給電子を溶接ヘッド(溶接台車)に設置しているため、この摺動給電子にアーク電源及びワイヤ電源から接続されている各々の給電ケーブルを、溶接ヘッドの移動に合せて移動できるようにしなければならず、その給電ケーブルの処理方法が厄介であるばかりでなく、摺動給電子の摩耗による給電不良の恐れや消耗部品の定期交換も必要になる。また、前記特開平８−１５５６４３号公報に記載の磁気吹き防止型溶接装置の溶接方法は溶接ワイヤを電極とするアーク溶接法ではなく、非消耗性のタングステンを電極とするアーク溶接法(ホットワイヤＴＩＧ溶接法)である。
【０００８】
また、前記特開平１０−９９９６６号公報に記載の上向・立向溶接方法は、溶融池に開先底部方向へローレンツ力を発生させながら溶接することで、上向き、立向きの溶接姿勢で生じ易い溶融金属の垂れ落ちや溶接ビードの形状悪化を改善するのに有効であると考えられる。しかし、所望のローレンツ力(磁力)を発生させるために、溶融池近傍へ設置する磁石、溶融池に挿入する添加ワイヤ、給電する電源が必要であり、装備が大型化、制御が複雑で操作性、使い勝手も低下する恐れがある。
【０００９】
本発明の目的は、溶接ワイヤを電極とするアーク溶接を用いる自動溶接方法において、溶接部やアークへ外部から磁界、磁力を与える電磁石などを設けることなく、アーク溶接の電流で生じるアーク磁気吹き現象による溶接品質の低下を抑制するにある。
【００１０】
【課題を解決するための手段】
アークの磁気吹き現象が溶接品質の低下を引き起こすのは、磁気吹き現象が突発的に不特定方向に発生するためである。発明者等は、磁気吹き現象が突発的に不特定方向に発生するのは、溶接の進行につれて溶接母材を流れる溶接電流の流れの方向や分布が変化する結果、磁力線の状態が変化することが原因であることに着目し、溶接中、溶接母材を流れる溶接電流の流れの方向や分布の変化を抑制する方策を探求して上記の課題を解決することができた。
【００１１】
すなわち、上記課題を解決する本発明は、長尺の第１部材（以下、適宜、長尺部材という。）の上面の離れた位置又は両端面に該第１部材よりも短い形状の２つの第２部材（以下、適宜、小物部材という。）を対向させて各々配置して溶接すべき２組の隅肉継手部又は重ね継手部を前記第１部材の上面位置又は両端面位置に各々形成し、溶接電源の一方の極性に接続された溶接トーチ及び溶接ワイヤを用いて前記継手部のアーク溶接を行う自動溶接方法において、前記２組の前記隅肉継手部又は重ね継手部に挟まれた中間位置の前記第１部材の上面又は下面の一箇所に前記溶接電源の他方の極性に接続された給電ケーブルを固定接続し、溶接時に給電される前記第１部材の溶接部分に流れる溶接電流で生じる磁力によって偏向されるアークを前記第２部材側へ偏向させた状態にして、前記継手部をそれぞれアーク溶接することを特徴とする。
【００１２】
溶接すべき継手部の溶接線位置、溶接条件を溶接装置側へ事前に教示設定して溶接を行う場合は、磁気吹きによるアークの偏向を予め補正しておくようにしてもよい。
【００１３】
また、互いに隣接する少なくとも一対の小物品部材が長尺部材との溶接線に対して互いに反対側になる位置に溶接されるときは、前記一対の小物品部材が対向設置される長尺部材の中間位置に前記部材側給電ケーブルを接続するようにすればよい。
【００１４】
さらに、溶接すべき継手部の溶接線位置や溶接条件を溶接装置側へ教示設定する場合、小物部材の板厚が長尺部材側より厚いときは、溶接ワイヤの狙い位置を両部材継手の交点位置より小物部材側へシフトした位置に設定し、反対に、前記小物部材の板厚が長尺部材側に対して同等以下のときには、溶接ワイヤの狙い位置を両部材継手の交点位置より長尺部材側へシフトした位置に設定して、溶接を行うようにするのが望ましい。
【００１５】
溶接線位置や溶接電流・電圧、溶接速度などの溶接条件を溶接装置側へ教示設定する時に、溶接方向と直交する左右方向に溶接トーチを揺動させるウィービング条件を追加設定しておき、アーク溶接の実行時に、溶接中のアークを非給電の小物品部材側へ偏向させた状態で、溶接トーチをウィービングさせてアークを左右揺動させながら継手部の溶接を行うようにしてもよい。
【００１６】
また、溶接すべき小物品部材と長尺部材の継手部の溶接線位置、溶接条件を教示設定する時に、溶接開始から終了に至るまでの溶接線全長の教示点を少なくとも開始側で２点以上、終了側で１点以上設定して、溶接最初のポイント点から次のポイント点、或いはその次のポイント点までを結ぶ溶接線を開始部、この開始部の最後尾のポイント点から溶接終了のポイント点までを結ぶ溶接線を定常溶接部、この定常溶接部終了のポイント点以降を溶接終了部として区別すると共に、この区別した各部分で所望の溶接条件が各々出力制御できるように設定しておき、アーク溶接の実行時に、溶接開始点から終了点に至る時間まで、溶接ワイヤと長尺部材との間で流れる溶接電流で生じる磁力線によってアークに加わる磁力の方向を溶接線から小物品部材に向かう方向に維持しながら溶接を行うようにするのがよい。
【００１７】
すなわち、本発明の自動溶接方法では、通電経路の不特定分散、溶接電流の分散分流をなくして磁気吹きによるアークの不安定化を解消するために、部材側給電ケーブルを、小物品部材を長尺部材に溶接する溶接線（溶接継手）に対して小物品部材と反対側（云いかえると、長尺部材を、前記溶接継手を境に前記小物品部材がある側とない側に分けたとき、小物品部材がない側）になる長尺部材の１箇所のみに接続する。そして部材側給電ケーブルをこのように接続することで、溶接ワイヤと長尺部材との間に流れる溶接電流の方向、小物品部材の存在による磁力線分布の非対称性に起因するアーク磁気吹きの方向（溶接アークの偏向方向）を、溶接線から小物品部材に向かう方向に維持させ、安定な偏向アーク及びワイヤ溶融・移行を保持しながら溶接することを可能にしている。
【００１８】
アーク偏向方向を安定させて溶接を行うことで、アーク切れやワイヤ溶融の乱れなどが防止でき、品質の良好な溶接部を得ることができる。しかも、外部から磁界、磁力を与える電磁石など器具の配備が不要となり、部材側給電ケーブルの量が削減でき、格別の費用を要することなく簡単に実施することができる。また、溶接する小物品部材と長尺部材の板厚が異なる場合、溶接ワイヤの狙い位置を板厚の厚い部材側へシフトさせて溶接を行うことで、厚肉部材側の溶融促進を図り、溶け込み形状が均一で良好な溶接結果が得られるようにしている。さらに、溶接線方向と直交する左右方向に溶接トーチを揺動させる動作（ウィービング動作）を加えて、溶接中のアークを小物品部材側へ偏向させた状態のままでアーク揺動させることによって、溶融池の攪拌促進と溶接部の溶融促進、ブローホールや溶け込み不良など溶接欠陥の発生が低減される。
【００１９】
なお、長尺部材とは、部材の形状が、溶接線方向の長さよりも、溶接線に直交する方向の長さが長い形状のものであり、小物品部材とは、長尺部材に溶接される、前記長尺部材よりも小形の部材である。
【００２０】
【発明の実施の形態】
以下、本発明の実施の形態を図面を参照して説明する。
【００２１】
図１は本発明の第１の実施の形態が適用される消耗電極方式の直流溶接装置の概略構成例を示す斜視図である。図示の溶接装置は、溝形鋼状の長尺部材１とこの長尺部材１上面にある２つの小物部材２を取付け溶接(溶接箇所３)するもので、溶接トーチ１６と、溶接トーチ１６の先端部にトーチケーブル１５を介して溶接ワイヤ１７を送るワイヤ送給装置１３とを搭載した溶接ロボット１１と、トーチ側給電ケーブル６で溶接トーチ１６に接続された溶接電源４と、制御ケーブル１２を介して溶接ロボット１１の動作制御を行うとともにインターフェース８を介して溶接電源４の出力制御を行う溶接制御装置９と、溶接電源４からすみ肉継手の溶接箇所３へ給電する部材側給電ケーブル５と、を含んで構成されている。前記トーチ側給電ケーブル６は溶接電源４の正極を溶接トーチ１６を介して溶接ワイヤ１７に接続し、部材側給電ケーブル５は、溶接個所３を挟んで小物品部材２の反対側になる、長尺部材１の中央寄りの位置２０と溶接電源４の負極を接続するように設置されている。この溶接電源４は、切替えスイッチによって直流波形の溶接電流、電圧と、パルス状波形の溶接電流、電圧を出力することができる。パルスを選択すると、溶接ワイヤの溶滴移行が制御でき、スパッタの発生が少ない溶接を行うことができる。
【００２２】
本実施の形態では、一対の小物品部材２が互いに対向して配置され、それぞれの溶接個所３が小物品部材２の互いに対向する側にあるため、前記部材側給電ケーブル５は、長尺部材１の小物品部材２の中間の位置に接続されている。溶接電源４と長尺部材１の他の場所を接続するケーブルは設けられていないし、小物品部材２側にも、通電経路の分散及び電流分流を避けるために、給電ケーブルは接続されていない。溶接ワイヤ１７には、前記トーチ側給電ケーブル６により、溶接トーチ１６を介して給電するようになっている。溶接制御装置９は、溶接ロボット１１の運転操作や溶接電源の出力設定を行う操作ボックス１０を含んで構成され、操作者は操作ボックス１０から溶接すべき継手部の溶接線位置、溶接条件、動作指令などを任意に教示設定することができる。すなわち、図示の溶接装置は、ティーチングプレイバック方式で自動溶接が行えるようになっている。
【００２３】
次に図２を参照して、図１に示した溶接装置を用いる本発明の実施の形態を説明する。図２の（１）、（２）は板厚が異なる継手溶接における溶接ワイヤ狙い位置を示す断面図で、図２の（３）は溶接時に長尺部材１を流れる溶接電流の電流経路とアークの磁気吹き方向を示す平面図である。溶接電源４と溶接される部材（溶接母材）を接続する部材側給電ケーブル５は、図示した長尺部材１の上面の、溶接個所３を挟んで小物品部材２の反対側になる、長尺部材１の中央寄りの位置２０に接続されている。この上面真下の下面位置に設置しても同じ結果となる。したがって、アーク溶接中の電流は、図２の（３）の電流経路２２に示したように、溶接トーチ１６先端部の溶接ワイヤ１７から溶接アークを経て長尺部材１側に図示した電流経路２２を矢印方向に流れ、この溶接電流（含むアーク）で矢印方向(時計廻り方向)に磁力線２３が生じる。この磁力線２３の一部が非給電の小物品部材２(縦板)によって短絡、曲折変化することになり、小物品部材２側の方向へ生じる磁力２４によって、溶接中のアークは小物品部材２側へ偏向することになる。このとき、長尺部材１を溶接個所３から部材側給電ケーブル５の接続点である位置２０に向かって流れる溶接電流の電流経路２２は、溶接トーチ１６の溶接方向２５に沿った進行に伴なって変化するが、溶接個所３から位置２０に向かうという基本的な方向は変化せず、したがって、溶接中のアークに作用する磁力２４の方向も、小物品部材２側にアークを偏向させる方向で安定する。アークの偏向する方向が安定することにより、アーク切れやワイヤ溶融の乱れなどが防止でき、品質の良好な溶接部を得ることができる。
【００２４】
なお、継手部材側と溶接トーチ側の給電ケーブル５、６の極性を反転(例えば、溶接ワイヤを陰極にしてアーク溶接を行う場合)させても、電流経路２２と磁力線２３が方向反転するために、磁力２４の生じる方向は変わらない。このように、アークの磁気吹き方向を非給電の小物品部材２側方向へ向かわせることで、安定な偏向アーク、良好なワイヤ溶融移行を保持しながら溶接を行うことができる。
【００２５】
また、図２の（１）、（２）に示したように、溶接すべきすみ肉継手部の溶接線位置、溶接条件を教示設定する時に、小物品部材２の板厚ｔ_２が長尺部材１側の板厚ｔ_１より厚い場合(ｔ_１＜ｔ_２)は、溶接ワイヤ狙い位置を小物品部材２側の方へＳ_１だけシフトさせた位置に定め、反対に、小物品部材２の板厚ｔ_２が長尺部材１側より薄い又は同等の場合(ｔ_１≧ｔ_２)には、長尺部材１側の方へＳ_２だけシフトさせた位置に定めて溶接を行うようにする。これは板厚が異なる継手の溶接の品質を維持する有効な手段であり、溶接ワイヤの狙い位置を板厚の厚い部材側へシフトさせて偏向アークを保持しながら溶接することで、融合不良や片溶けビードの発生が未然防止できて、図３に示すように溶け込み形状の良好なすみ肉溶接部３０を得ることができる。前記Ｓ_１，Ｓ_２の値は、予め、ｔ_１、ｔ_２の値に対応して実験を行って適切な値を設定しておく必要がある。
【００２６】
図２の（１）、（２）に示したように、長尺部材と小物品部材のいずれか一方の肉厚面が他方の部材の表面に当接して、あるいはギャップをおいて配置されて溶接継手を形成するとき、該肉厚面と当該部材の溶接トーチ側表面の交点位置が、ワイヤ狙い位置の基準となり、ワイヤ狙い位置はこの基準位置から長尺部材と小物品部材のいずれか厚肉側の方にずらせて設定される。
【００２７】
さらに、溶接線方向と直交する左右方向に溶接トーチを揺動させるウィービング動作を加えて、溶接中のアークを非給電の小物部材側へ偏向させた状態のままでアーク揺動させることによって、溶融池の攪拌と溶接部の溶融が促進され、ブローホールや溶け込み不良など溶接欠陥の発生が防止されて、溶接品質及び信頼性が向上する。
【００２８】
図４、図５に本発明の第２の実施の形態を示す。図５は住宅建築で使用される鉄骨柱の一部分を示す概略図で、長尺柱部材１ａの両端面に小物品部材であるプレート２ａを内面側から取付け溶接する一例(片側の溶接箇所3a、3bのみを図示)である。この溶接継手を構成する部材の板厚は、プレート２ａの方が長尺柱部材１ａより厚く、両部材共に耐食性、耐久性の優れた亜鉛メッキ鋼板が使用されている。
【００２９】
図４はこの取付け溶接を行う自動溶接装置の一例を示す概略構成図である。本実施の形態では、回転ドラム２６の上の柱固定台２７に、長尺柱部材１ａが一対の柱クランプ給電板２８によりクランプされて固定され、固定された長尺柱部材１ａの両端面に、それぞれプレート固定冶具２９にて押付けて位置決め固定された左右のプレート２aを内面側から各々取付け溶接する例を示している。各プレート２ａの溶接継手部分は各プレートについて各々３箇所（底辺部の溶接個所３ａが１箇所，側壁部の溶接個所３ｂが２箇所）あり、２台の独立した溶接ロボット１１によって左右分担して連続的に溶接される。溶接ロボット１１は、それぞれ溶接制御装置９に制御され、各溶接制御装置９は溶接電源４をも制御する。また、前記回転ドラム２６は、その軸線を回転軸として４５度又は９０度づつ回転可能になっており、回転した位置でその状態を保持、固定することで、溶接しようとする継手を溶接し易い姿勢で溶接できるようにしている。
【００３０】
独立した一対の溶接電源４の負極から溶接母材である長尺柱部材１aへ給電する部材側給電ケーブル５は、プレート２aの溶接箇所から、該溶接個所を挟んでプレート２aの反対側に離れた長尺柱部材１aの中寄り上面に設置してある脱着自在な柱クランプ給電板２８に各々接続されている。プレート２ａ側には、通電経路の分散及び電流分流を避けるために、部材側給電ケーブル５は接続されていない。
【００３１】
なお、プレート固定治具２９に部材側給電ケーブル５を並列接続してプレート２ａ側にも分散給電しながら溶接した時には、不特定方向へのアークのふらつきやアーク切れの発生によってアーク溶接現象が著しく乱れて、ビード切れやうねりビード、融合不良、ブローホールなどの溶接欠陥が多発する結果になり易い。
【００３２】
溶接トーチ１６には、溶接ワイヤ１７に給電するトーチ側給電ケーブル６がそれぞれ溶接電源４の正極から接続されている。長尺柱部材１ａの両端面それぞれにプレート２ａを取付け、溶接する動作を左右ほぼ同時に行っても、各々の溶接ロボット１１、溶接電源４、溶接制御装置９は独立しており、かつ、溶接位置も遠く離れているのでお互いに干渉し合うことはない。
【００３３】
図６は、上記の溶接で生じる電流経路とアークの磁気吹き方向を示す概略図である。図中の溶接箇所３ａを溶接方向２５で示される方向にアーク溶接する時の電流経路２２は、溶接ワイヤ１７から矢印方向に、長尺柱部材１ａ、柱クランプ給電板２８を経由して部材側給電ケーブル５に流れるルートである。また、溶接中の溶接ワイヤ１７先端のアーク１９外周囲に生じる時計廻り方向の磁力線２３は、非給電のプレート２ａによって概ね図示したように短絡、曲折変化する。この結果、磁力２４が非給電のプレート２ａ側方向に作用するとともに、磁力２４の発生方向に溶接アークが引き寄せられて曲がることになる。この磁力２４の作用によってプレート２ａ側方向に曲げられた偏向アークは安定して持続保持され、また、ワイヤ溶融移行も安定しており、溶接を良好に行うことができる。同様に、姿勢の異なる他の溶接箇所３ｂも、上述した磁力２４作用によってアークの偏向方向が安定するため、良好な溶接を行うことができる。
【００３４】
図７は、上記した鉄骨柱溶接における適正条件裕度を検討した一例で、プレート２ａが長尺柱部材１ａよりも厚肉の組み合わせで溶接トーチ位置Ｙ(ワイヤ狙い位置)と継手のギャップＧを変化させた時の溶接良否の判定結果を示す。溶接条件は図中に示した通りであり、溶接トーチを揺動させるウィービング動作も行っている。○印は溶接外観及び溶け込み形状が良好、×印は片溶けや溶け落ちによる外観不良、△印は溶け込み形状の不良を、それぞれ示している。図７に示した溶接継手の場合、溶接継手の交点位置は、Ｙ＝０の面と長尺柱部材の溶接トーチ側の表面の交点である。良好な溶接結果が得られる範囲は、溶融促進が必要な厚肉のプレート側へワイヤ狙い位置をシフト（−１．５≧Ｙ≧０ｍｍ）した領域にあり、また、薄肉の柱側との継手ギャップＧも０．５ｍｍまで許容できることを示している。このように継手の厚板側へ溶接トーチのワイヤ狙い位置をシフトさせると共に、溶接トーチを左右に揺動させるウィービング動作を加えたアーク溶接を行うことで、溶融池の攪拌及び溶接部の溶融が促進され、ブローホールや溶け落ちなど溶接欠陥が防止できると同時に条件裕度が拡大でき、溶け込み形状が均一で品質の良好な溶接結果を得ることができる。
【００３５】
図８に本発明の第３の実施の形態を示す。本実施の形態は、平板状の長尺部材１の上面に、小物品部材である重ねプレート部材２ｂを隅肉状の溶接個所３ｃの溶接により取付ける場合の例である。図８の（１）は継手部材の概略形状と溶接個所及び溶接トーチの狙い位置を示す斜視図、図８の（２）は溶接で生じる電流経路とアークの磁気吹き方向を示す平面図、図８の（３）は重ね溶接部のビード断面形状３０を示す断面図である。図では、溶接制御装置、溶接電源、溶接ロボット、トーチ側給電ケーブルは省略されているが、溶接トーチ１６は溶接ロボットに搭載され、トーチ側給電ケーブルで溶接電源に接続されている。また、溶接電源から継手部材側へ給電する部材側給電ケーブル５は、溶接個所３ｃからこの溶接個所３ｃを挟んで重ねプレート部材２ｂと反対側に離れた長尺部材１の中央寄りの上部位置(下部位置でも可能)に設置されている。
【００３６】
この例では、長尺部材１側の板厚ｔ_１の方が重ねプレート部材２ｂの板厚ｔ_２より厚い(ｔ_１>ｔ_２)ために、溶接トーチ１６(溶接ワイヤ１７)の狙い位置を長尺部材１側へＳ_２だけシフトさせて溶接を行った。図８の(２)に示したようにアーク溶接で流れる電流によりアークに作用する磁力２４の方向は、アークを非給電の重ねプレート部材２ｂ側へ偏向させる方向となり、長尺部材１を流れる溶接電流の電流経路２２が図示の経路に安定しているため、前記磁力２４の方向も、図示の方向に安定する。このため、上述したように溶接中のアークは、磁力２４の作用方向に引き寄せられて安定に保持されることになる。したがって、重ねプレート部材２ｂ側方向に磁力２４で偏向するアークを、トーチ位置シフト機能によって溶接ワイヤ１７の狙い位置を厚肉の長尺部材１側へＳ_２だけシフトさせて溶接を行うことで、長尺部材１側の溶融が促進され、溶け込みの良好な結果を得ることができた。
【００３７】
図９、図１０に本発明の第４の実施の形態を示す。本実施の形態は、円筒形状構造の長尺円筒部材１ｂの左右両端面に小物品部材であるフランジ２ｃを取付け溶接する場合の例である。図１０の（１）に、この継手部材の一部を拡大した溶接個所と溶接トーチの狙い位置を、図１０の（２）に、溶接部のビード断面形状を、それぞれ断面図で示してある。長尺円筒部材１ｂは、回転駆動装置３１に配置された回転ローラ３２上に搭載され、回転ローラ３２によって円周面を駆動されて軸線を回転軸として回転される。長尺円筒部材１ｂの中央寄りの上部位置（両端に取付けられるフランジの中間位置）に可動式給電器３３が設置され、この可動式給電器３３と溶接電源（図示省略）の負極が部材側給電ケーブル５により接続されている。可動式給電器３３は、回転する長尺円筒部材１ｂへ滑動しつつ給電をするもので、長尺円筒部材１ｂが回転してもその上側の位置にとどまるようになっている。溶接トーチ１６は溶接ロボット(図示省略)に搭載され、図示されていない溶接電源の正極からトーチ先端部の溶接ワイヤ１７へ給電するトーチ側給電ケーブル６が接続されている。
【００３８】
長尺円筒部材１ｂの左右両端面に取付けられるフランジ２ｃは、その互いに対向する側の面と長尺円筒部材１ｂの円筒部外周面で形成される隅肉継手の溶接で取付けられるようになっており、フランジ２ｃを溶接する動作は、事前に教示入力された溶接位置や溶接条件など教示データに基づいて、回転駆動装置３１と同調させて自動でそれぞれ行うようになっている。溶接ワイヤ１７の狙い位置は、フランジ２ｃの板厚ｔ_２より厚肉である長尺円筒部材１ｂ側にＳ_２だけシフトさせた位置に設定してある。また、溶接は、溶接トーチ１６を溶接線方向と直交する左右方向に揺動させるウィービング動作も加えて行われる。
【００３９】
本実施の形態において、溶接時に長尺円筒部材１ｂを流れる溶接電流の経路は図９に示す電流経路２２で安定する。この結果、溶接電流により溶接アークに作用する磁力の方向は、アークをフランジ２ｃ側方向に偏向させる方向で安定し、アーク磁気吹き現象の作用方向の変動による溶接欠陥の発生は抑制される。
【００４０】
上述したように、アーク溶接の電流で生じる磁界、アーク磁気吹き現象による磁力２４が作用する方向をフランジ２ｃ側方向に安定させ、かつ、その偏向アークを長尺円筒部材１ｂ側に適量シフトさせると共に、ウィービング動作のアーク溶接を行うことで、厚肉部材側の溶融が促進され、図１０の(２)に示したように溶け込み形状の良好な溶接結果を得ることができる。
【００４１】
図１１は上記各実施の形態における条件制御ブロック線図の例を示し、横軸の時間に対応する縦軸には溶接電流Ｉa（Ａ）、ワイヤ送り速度Ｗｆ（ｍ／min）、溶接電圧Ｅa（Ｖ）、溶接速度Ｖｓ（mm／min）、ウィービング動作の有無、シールドガスＳＧの制御動作、をそれぞれ表示している。図中の条件番号(▲１▼〜▲４▼)は、溶接開始のポイント点(Ｐ１)から溶接終了のポイント点(Ｐ３)に至るまでの各過程ごとの出力条件であり、表１にまとめて示した。すなわち、溶接すべき継手部(図１、図４、図８参照)の溶接線位置、溶接条件を操作ボックス１０から溶接制御装置に９に教示設定する時に、まず、溶接線全長の教示ポイント点（地点）を少なくとも開始側で２点以上、終了側で１点以上設定する。溶接開始地点（Ｐ１，アークスタート地点）から定常溶接開始地点（Ｐ２）までを開始部(▲１▼、▲２▼)、この定常溶接開始地点から定常溶接の終了地点に到達するまでを定常溶接部(▲３▼)、この定常溶接の終了点到達以降を溶接終了部(▲４▼)として区別すると共に、この区別した各部分で所定の溶接条件(表１記載の溶接条件)が各々出力できるように設定する。
【００４２】
【表１】

例えば、ここではシールドガスの供給を開始してからＴ_３時間後に、Ｐ１地点に設定された溶接トーチ１６に溶接ワイヤを送給(ワイヤ送り速度Wf1)するとともに、小電流Ia1、小電圧Ea1を印加してアークを発生させて溶融プールを形成させる。アークがスタートしてＴ_１時間経過後に溶接電流、電圧、ワイヤ送り速度を増加(Ia2、Ea2、Wf2)させると共に、溶接トーチの走行(溶接速度Ｖｓ２)とウィービング動作(揺動幅Ｗ、サイクルｆ)を開始させる。そして、溶接トーチ１６が定常溶接開始の地点Ｐ２に到達した時点で定常溶接条件(Ea3、Ia3、Wf3)に移行させ、その溶接状態を溶接終了地点Ｐ３まで継続する。前記のウィービング動作はＰ２点から開始するようにしてもよい。その後、溶接終了地点Ｐ３に到達すると、トーチ走行とウィービング動作が停止され、溶接電圧、電流及びワイヤ送り速度の値を減少(Ea4、Ia4、W4，f4)させて、溶融プールを縮小及び凹み形状を平滑にするＴ_２時間経過後にアークを停止する。アークを停止してからアフターフロー時間Ｔ_４経過後にシールドガスを停止、溶接トーチを回避移動させて溶接が終了する。
【００４３】
各過程の溶接条件は、構造物や溶接継手の仕様に応じて各々適正な値を教示設定すればよい。このようにして溶接の開始から終了に至るまでの条件制御を適正に行うと共に、溶接ワイヤと長尺部材との間に流れる溶接電流で生じる磁力作用、アーク磁気吹き現象が発現する方向を、溶接中のアークを非給電の小物品部材側方向に偏向させる方向に安定させることで、溶接の開始部から定常溶接部及び終了部まで溶接全長にわたって高品質な溶接結果を得ることができる。
【００４４】
【発明の効果】
以上述べたように本発明によれば、アークのふらつきやアーク切れ、ワイヤ溶融の乱れなどが防止でき、安定な偏向アーク及びワイヤ溶融移行の溶接によって品質の良好な溶接結果を得ることができ、生産性向上、コスト低減に寄与できる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態を示す斜視図である。
【図２】図１の実施の形態の部分の詳細を示す断面図及び平面図である。
【図３】図２に示した溶接方法で実施した溶接部のビード断面形状の例を示す断面図である。
【図４】本発明の第２の実施の形態を示す概念図である。
【図５】図４に示した長尺柱部材及びプレートを示す斜視図である。
【図６】図４に示した実施の形態における電流経路とアークの磁気吹き方向を示す平面図である。
【図７】本発明の第２の実施の形態において、プレートの板厚が長尺柱部材の板厚よりも厚い場合の、継手ギャップに対応する適正なワイヤ狙い位置の例を示すグラフである。
【図８】本発明の第３の実施の形態を示す斜視図、平面図及び断面図である。
【図９】本発明の第４の実施の形態を示す斜視図である。
【図１０】図９に示した実施の形態におけるトーチ狙い位置と溶接部のビード断面形状を示す断面図である。
【図１１】本発明の実施の形態における溶接条件制御の例を示すタイムチャートである。
【符号の説明】
１長尺部材
１ａ長尺柱部材
１ｂ長尺円筒部材
２小物品部材
２ａプレート
２ｂ重ねプレート部材
２ｃフランジ
３，３ａ，３ｂ，３ｃ溶接個所
４溶接電源
５部材側給電ケーブル
６トーチ側給電ケーブル
８インターフェース
９溶接制御装置
１０操作ボックス
１１溶接ロボット
１２制御ケーブル
１３ワイヤ送給装置
１５トーチケーブル
１６溶接トーチ
１７溶接ワイヤ
２０部材側給電ケーブルが接続されている位置
２２電流経路
２３磁力線
２４磁力
２５溶接方向、
２６回転ドラム
２７柱固定台
２８柱クランプ給電板
２９プレート固定治具
３０ビード断面形状
３１回転駆動装置
３２回転ローラ
３３可動式給電器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an arc welding method using a welding wire as an electrode, and more particularly to an automatic welding method in which a small article member is welded to a long member in consideration of an arc magnetic blowing phenomenon caused by an arc welding current.
[0002]
[Prior art]
In general, the arc welding method using welding wire as an electrode is much faster and more efficient than the arc welding method using non-consumable tungsten as an electrode. Widely used for assembly welding of machine parts and elevator parts. However, in DC arc or pulsed arc welding, magnetic field lines are generated by the welding current flowing between the electrode and the weld base material, and the magnetic field line density varies depending on the position around the arc or changes in the current path. It is known that a magnetic blowing phenomenon in which the arc is deflected by a magnetic force occurs when the position of the arc changes depending on the position, and that the deflection of the arc tends to adversely affect the welding result.
[0003]
For this reason, assembling and welding sites using consumable electrode type automatic welding devices for direct current or pulse current, as a simple means for suppressing the magnetic blowing phenomenon of arcs, for example, a plurality of locations where welding base materials are dispersed are used as members. A method is used in which a welding power source is connected to a welding power source by a side power supply cable to distribute the energization path unspecified, and the welding current flowing through the welding base material is distributed and divided. Also, an electromagnet or the like is disposed near the tip of the welding torch or near the welded portion to apply a magnetic field to the arc and the molten pool to prevent the arc from being blown or to forcibly deflect the arc or the molten pool in a specific direction. A method may be used. For the phenomenon of arc magnetic blown and the method of suppressing and controlling the direction with a magnet, see “Arc Welding Phenomenon: Section 4.3 Arc Magnetic Blow” (PP.153-161, Sangyo Publishing, Ando).・ It is outlined in Hasegawa's first edition issued on July 15, 1957.
[0004]
Japanese Patent Application Laid-Open No. 7-32146 discloses a technique for detecting and displaying the strength (magnetic force) and direction of a magnetic field generated by an arc welding current by providing a magnetic sensor unit at the tip of a torch. Furthermore, as an example of an apparatus for preventing arc magnetic blowing due to magnetic field fluctuations, an arc current and wire current sliding power supply for sliding power supply to the base metal side is provided in a welding head near the arc welding portion. There is a magnetic blow prevention type welding apparatus described in Japanese Patent Application Laid-Open No. 8-155643. In addition, an electric current is passed through the weld pool in the melt formed direction (power is supplied to the added wire) and a magnetic field (magnet is installed) in the direction perpendicular to the weld pool to generate a Lorentz force (magnetic force) in the weld bottom direction. As an example of welding, there is an upward / vertical welding method described in JP-A-10-99966. In addition, several techniques for installing and using electromagnets have been proposed.
[0005]
[Problems to be solved by the invention]
A conventional method is used that suppresses magnetic blowing by connecting a plurality of locations where the welding base material is dispersed to a welding power source with a member-side power supply cable to disperse the energization path to unspecified paths and flowing the welding current in a distributed manner. Because the flow of welding current varies depending on the length and thickness of the member side power supply cable, the size and conductivity of the long member and the small article member, the contact state, the connection position and fixing method of the member side power supply cable, etc. It is difficult to evenly distribute the welding current. For this reason, the above-mentioned conventional method results in an unspecified and complicated energization path and unstable current distribution, and an arc magnetic blowing phenomenon suddenly occurs in an unspecified direction, causing arc breakage, arc turbulence, wire melting. Turbulence, and droplet scattering at the time of wire droplet transfer tends to occur, which may lead to deterioration of the arc welding phenomenon and generation of welding defects.
[0006]
On the other hand, the magnetic blow detection method and apparatus for arc welding described in JP-A-7-32146 are effective means for detecting the strength and direction of a magnetic field generated by a welding current. The phenomenon itself cannot be suppressed or prevented. Moreover, since the magnetic sensor unit is installed at the tip of the torch, it is necessary to make the structure to reduce and suppress the influence of radiant heat on the magnetic sensor unit due to arc welding. The torch operability during welding may be reduced.
[0007]
In addition, the magnetic blow prevention type welding apparatus described in the above-mentioned Japanese Patent Application Laid-Open No. 8-155643 concentrates the base material energization path of arc current and wire current at a specific position in the vicinity of the arc welded portion, thereby causing stray current and magnetic field fluctuation. It is thought that it is effective for prevention of arc and suppression of arc magnetic blow. However, since the sliding power supply for the arc current and the wire current is installed in the welding head (welding carriage), each power supply cable connected to the sliding power supply from the arc power source and the wire power source, It must be able to move according to the movement of the welding head. Not only is the handling method of the power supply cable troublesome, but there is also a risk of power supply failure due to wear of sliding power supply and periodic replacement of consumable parts. Become. Also, the welding method of the magnetic blow prevention type welding apparatus described in the above-mentioned JP-A-8-155543 is not an arc welding method using a welding wire as an electrode, but an arc welding method (hot wire) using non-consumable tungsten as an electrode. TIG welding method).
[0008]
Further, the upward / vertical welding method described in JP-A No. 10-99966 is generated in an upward and vertical welding posture by welding while generating a Lorentz force toward the groove bottom toward the weld pool. It is thought that it is effective for improving easy dripping of molten metal and deterioration of the shape of the weld bead. However, in order to generate the desired Lorentz force (magnetic force), a magnet installed in the vicinity of the molten pool, an additional wire inserted into the molten pool, and a power supply for power supply are required. There is also a risk that the usability will be reduced.
[0009]
An object of the present invention is an arc welding method using arc welding with a welding wire as an electrode, and an arc magnetic blowing phenomenon caused by an arc welding current without providing an electromagnet or the like for applying a magnetic field or a magnetic force to the welded part or the arc from the outside. It is in suppressing the deterioration of the welding quality due to.
[0010]
[Means for Solving the Problems]
The reason why the magnetic blowing phenomenon of the arc causes deterioration of the welding quality is because the magnetic blowing phenomenon suddenly occurs in an unspecified direction. The inventors have found that the magnetic blowing phenomenon suddenly occurs in an unspecified direction because the direction and distribution of the flow of the welding current flowing through the welding base material changes as the welding progresses, resulting in a change in the state of the lines of magnetic force. Focusing on the cause of the above, it was possible to solve the above-mentioned problems by searching for a measure for suppressing changes in the direction and distribution of the flow of the welding current flowing through the weld base metal during welding.
[0011]
That is, the present invention for solving the above-described problems is a long first member (hereinafter referred to as a long member as appropriate). Distant position on the upper surface or both end surfaces Shorter than the first member Two The second member (hereinafter referred to as a small member as appropriate). Facing each other Should be placed and welded Two sets The fillet joint or lap joint is positioned on the top surface of the first member. Or at both end positions In an automatic welding method for performing arc welding of the joint using a welding torch and a welding wire connected to one polarity of a welding power source, In one place on the upper surface or lower surface of the first member at an intermediate position sandwiched between the two sets of fillet joints or lap joints Feeding cable connected to the other polarity of the welding power source Solidify The joint portion is fixedly connected and the arc deflected by the magnetic force generated by the welding current flowing in the welding portion of the first member that is fed during welding is deflected to the second member side. Respectively It is characterized by arc welding.
[0012]
When welding is performed by teaching and setting the welding line position and welding conditions of the joint portion to be welded to the welding apparatus side in advance, the deflection of the arc due to magnetic blowing may be corrected in advance.
[0013]
Further, when at least a pair of small article members adjacent to each other are welded to positions opposite to each other with respect to the welding line with the long member, the pair of small article members What is necessary is just to make it connect the said member side electric power feeding cable to an intermediate position.
[0014]
Furthermore, when teaching and setting the welding line position and welding conditions of the joint part to be welded to the welding device side, when the plate thickness of the accessory member is thicker than that of the long member side, the target position of the welding wire is set at the intersection of the two member joints. If the plate thickness of the small member is equal to or less than that of the long member, the target position of the welding wire is longer than the intersection of the two member joints. It is desirable to perform welding by setting the position shifted to the member side.
[0015]
When teaching welding settings such as welding line position, welding current / voltage, welding speed, etc. to the welding equipment side, weaving conditions for swinging the welding torch in the left-right direction perpendicular to the welding direction are additionally set, and arc welding is performed. At the time of execution, the joint portion may be welded while weaving the welding torch and swinging the arc left and right while the arc being welded is deflected toward the non-powered small article member.
[0016]
Also, when teaching and setting the welding line position and welding conditions of the joint part between the small article member and the long member to be welded, at least two teaching points for the total length of the welding line from the start to the end of welding are provided. Set one or more points on the end side, start the welding line connecting the first point point of welding to the next point point or the next point point, and the end of welding from the last point point of this starting point The welding line connecting up to the point point is distinguished as a steady welding part, and the point after the point at the end of the steady welding part is distinguished as a welding end part, and the desired welding conditions are set so that output control can be performed for each of the distinguished parts. When performing arc welding, the direction of the magnetic force applied to the arc by the magnetic field generated by the welding current flowing between the welding wire and the long member from the welding start point to the end point is changed from the welding line to the accessory. It is preferable to perform the welding while maintaining the direction towards the member.
[0017]
That is, in the automatic welding method of the present invention, in order to eliminate the unspecified dispersion of the energization path and the dispersion / distribution of the welding current and to eliminate arc instability due to magnetic blowing, The side opposite to the small article member with respect to the welding line (welded joint) to be welded to the scale member (in other words, when the long member is divided into the side where the small article member is present and the side where the small article member is not present with the weld joint as a boundary) It is connected to only one part of the long member that becomes the side where there is no small article member. And by connecting the member side feeding cable in this way, the direction of the welding current flowing between the welding wire and the long member, the direction of the arc magnetic blowing due to the asymmetry of the magnetic field line distribution due to the presence of the small article member ( The welding arc deflection direction) is maintained in the direction from the welding line toward the small article member, and welding can be performed while maintaining a stable deflection arc and wire melting / transition.
[0018]
By performing welding while stabilizing the arc deflection direction, it is possible to prevent arc breakage, wire melting disturbance, and the like, and to obtain a welded portion with good quality. In addition, it is not necessary to install an instrument such as an electromagnet that applies a magnetic field or a magnetic force from the outside, the amount of the member-side power supply cable can be reduced, and it can be easily implemented without any special cost. In addition, when the plate thickness of the small article member to be welded is different from that of the long member, the welding position is shifted to the thick member side of the welding wire to perform welding, thereby promoting melting on the thick member side, The penetration shape is uniform and good welding results are obtained. Furthermore, by adding an operation (weaving operation) for swinging the welding torch in the left-right direction perpendicular to the weld line direction, by swinging the arc while the arc being welded is deflected to the small article member side, Generation of weld defects such as accelerated stirring of the molten pool, accelerated melting of the weld, blow holes and poor penetration is reduced.
[0019]
The long member is a member whose shape is longer in the direction perpendicular to the weld line than the length in the weld line direction, and the small article member is welded to the long member. The member is smaller than the long member.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is a perspective view showing a schematic configuration example of a consumable electrode type DC welding apparatus to which the first embodiment of the present invention is applied. The welding apparatus shown in the figure is a device that welds and welds a grooved steel-like long member 1 and two small members 2 on the upper surface of the long member 1 (welding point 3). A welding robot 11 equipped with a wire feeding device 13 for feeding a welding wire 17 through a torch cable 15 at the tip, a welding power source 4 connected to the welding torch 16 with a torch side power supply cable 6, and a control cable 12 A welding control device 9 for controlling the operation of the welding robot 11 via the interface 8 and controlling the output of the welding power source 4 via the interface 8, a member-side power feeding cable 5 for feeding power from the welding power source 4 to the welded portion 3 of the fillet joint, It is comprised including. The torch side power supply cable 6 connects the positive electrode of the welding power source 4 to the welding wire 17 via the welding torch 16, and the member side power supply cable 5 is on the opposite side of the small article member 2 with the welding point 3 interposed therebetween. It is installed so as to connect the position 20 near the center of the scale member 1 and the negative electrode of the welding power source 4. The welding power source 4 can output a welding current and voltage having a DC waveform and a welding current and voltage having a pulse waveform by a changeover switch. When the pulse is selected, the droplet transfer of the welding wire can be controlled, and welding with less spatter can be performed.
[0022]
In the present embodiment, since the pair of small article members 2 are arranged to face each other and the respective welding locations 3 are on the opposite sides of the small article member 2, the member side feeding cable 5 is a long member. One small article member 2 is connected to an intermediate position. A cable for connecting the welding power source 4 and the other part of the long member 1 is not provided, and no feeding cable is connected to the small article member 2 side in order to avoid dispersion of the energization path and current splitting. Power is supplied to the welding wire 17 via the welding torch 16 by the torch side power supply cable 6. The welding control device 9 is configured to include an operation box 10 for performing an operation operation of the welding robot 11 and an output setting of a welding power source. An operator can weld a weld line position, a welding condition, and an operation of a joint portion to be welded from the operation box 10. Instructions etc. can be arbitrarily taught and set. That is, the illustrated welding apparatus can perform automatic welding by the teaching playback method.
[0023]
Next, with reference to FIG. 2, an embodiment of the present invention using the welding apparatus shown in FIG. 1 will be described. 2 (1) and (2) are cross-sectional views showing the welding wire aiming positions in joint welding with different plate thicknesses, and (3) in FIG. 2 is the current path and arc of the welding current flowing through the long member 1 during welding. It is a top view which shows the magnetic blowing direction. A member-side power supply cable 5 that connects a welding power source 4 and a member to be welded (welding base material) is the long side of the upper surface of the illustrated long member 1 that is on the opposite side of the small article member 2 across the welding point 3. The scale member 1 is connected to a position 20 near the center. The same result is obtained even if it is installed at the lower surface position directly below the upper surface. Therefore, the current during arc welding is shown in the current path 22 shown in FIG. 2 (3), the current path 22 shown on the long member 1 side from the welding wire 17 at the tip of the welding torch 16 through the welding arc. The magnetic field lines 23 are generated in the arrow direction (clockwise direction) by this welding current (including arc). A part of the magnetic force line 23 is short-circuited and bent by the non-powered small article member 2 (vertical plate), and the arc during welding is caused by the magnetic force 24 generated in the direction toward the small article member 2. Will be deflected to the side. At this time, the current path 22 of the welding current flowing through the long member 1 from the welding location 3 toward the position 20 which is the connection point of the member-side power supply cable 5 is accompanied by the progress of the welding torch 16 along the welding direction 25. However, the basic direction from the welding point 3 toward the position 20 does not change. Therefore, the direction of the magnetic force 24 acting on the arc during welding is also the direction in which the arc is deflected toward the small article member 2 side. Stabilize. By stabilizing the direction in which the arc is deflected, it is possible to prevent arc breakage, disorder of wire melting, and the like, and to obtain a welded portion with good quality.
[0024]
In addition, even if the polarity of the

feeding cables

5 and 6 on the joint member side and the welding torch side is reversed (for example, when arc welding is performed using the welding wire as a cathode), the direction of the current path 22 and the line of magnetic force 23 is reversed. The direction in which the magnetic force 24 is generated does not change. In this way, welding can be performed while maintaining a stable deflection arc and good wire melting transition by directing the arc magnetic blowing direction toward the non-powered small article member 2 side.
[0025]
Further, as shown in (1) and (2) of FIG. 2, when teaching and setting the welding line position and welding conditions of the fillet joint portion to be welded, the thickness t of the small article member 2 is set. ₂ Is the thickness t of the long member 1 side ₁ Thicker case (t ₁ <T ₂ ) Move the welding wire aiming position toward the small article member 2 side. ₁ In the opposite direction, the thickness t of the small article member 2 is determined. ₂ Is thinner than or equal to the long member 1 side (t ₁ ≧ t ₂ ) To the long member 1 side S ₂ It is determined that the position is shifted only by welding. This is an effective means of maintaining the welding quality of joints with different plate thicknesses. By shifting the target position of the welding wire to the thicker member side and welding while holding the deflection arc, fusion failure and Generation of a piece melt bead can be prevented in advance, and a fillet weld 30 having a good melt shape can be obtained as shown in FIG. S ₁ , S ₂ The value of ₁ , T ₂ It is necessary to conduct an experiment corresponding to the value of and set an appropriate value.
[0026]
As shown in (1) and (2) of FIG. 2, the thick surface of one of the long member and the small article member is in contact with the surface of the other member or arranged with a gap. When forming a welded joint, the position of the intersection of the thick surface and the surface of the welding torch side of the member becomes the reference for the wire aiming position, and the wire aiming position is the thickness of either the long member or the small article member from this reference position. It is set by shifting towards the meat side.
[0027]
Furthermore, by adding a weaving operation that swings the welding torch in the left-right direction perpendicular to the weld line direction, the arc is melted by swinging the arc while the arc being welded is deflected to the non-powered accessory member side. The agitation of the pond and the melting of the welded portion are promoted, the occurrence of welding defects such as blow holes and poor penetration is prevented, and the welding quality and reliability are improved.
[0028]
4 and 5 show a second embodiment of the present invention. FIG. 5 is a schematic view showing a part of a steel column used in a residential building. An example of attaching and welding a plate 2a, which is a small article member, to both end surfaces of a long column member 1a from the inner surface side (welded spot 3a on one side, Only 3b is shown). As for the plate thickness of the members constituting this welded joint, the plate 2a is thicker than the long columnar member 1a, and both members are made of galvanized steel plates having excellent corrosion resistance and durability.
[0029]
FIG. 4 is a schematic configuration diagram showing an example of an automatic welding apparatus for performing the attachment welding. In the present embodiment, the long column member 1a is clamped and fixed to the column fixing base 27 on the rotating drum 26 by a pair of column clamp power supply plates 28, and is fixed to both end surfaces of the fixed long column member 1a. In this example, the left and right plates 2a, which have been pressed and fixed by the plate fixing jig 29, are respectively attached and welded from the inner surface side. There are three welded joint portions of each plate 2a for each plate (one weld point 3a on the bottom side and two weld points 3b on the side wall), which are shared by the two independent welding robots 11 on the left and right. Welded continuously. The welding robot 11 is controlled by the welding control device 9, and each welding control device 9 also controls the welding power source 4. Further, the rotary drum 26 can be rotated by 45 degrees or 90 degrees with the axis thereof as the rotation axis, and by maintaining and fixing the state at the rotated position, the joint to be welded can be easily welded. It can be welded in a posture.
[0030]
The member-side power supply cable 5 that feeds power from the negative electrodes of the independent pair of welding power sources 4 to the long columnar member 1a, which is the welding base material, is separated from the welded portion of the plate 2a to the opposite side of the plate 2a across the welded portion. The long column member 1a is connected to a detachable column clamp power supply plate 28 installed on the middle upper surface. The member side power supply cable 5 is not connected to the plate 2a side in order to avoid dispersion of the energization path and current splitting.
[0031]
When the member-side power supply cable 5 is connected in parallel to the plate fixing jig 29 and welding is performed while supplying power to the plate 2a in a distributed manner, the arc welding phenomenon is remarkably caused by the occurrence of arc wobbling or arc breakage in an unspecified direction. Disrupted, it tends to result in frequent weld defects such as bead breaks, waviness beads, poor fusion, and blowholes.
[0032]
The welding torch 16 is connected to the torch side feeding cable 6 for feeding the welding wire 17 from the positive electrode of the welding power source 4. Even if the plate 2a is attached to each of both end faces of the long columnar member 1a and the welding operation is performed substantially simultaneously on the left and right, the welding robot 11, the welding power source 4, and the welding control device 9 are independent, and the welding position Because they are far away, they will not interfere with each other.
[0033]
FIG. 6 is a schematic diagram showing a current path generated in the above welding and a magnetic blowing direction of the arc. The current path 22 when arc-welding the welding spot 3a in the drawing in the direction indicated by the welding direction 25 is the member side via the long column member 1a and the column clamp power supply plate 28 in the arrow direction from the welding wire 17. This is a route that flows through the power supply cable 5. Further, the magnetic force line 23 in the clockwise direction generated around the arc 19 at the tip of the welding wire 17 during welding is short-circuited and bent as shown in FIG. As a result, the magnetic force 24 acts in the direction of the non-power-feeding plate 2a, and the welding arc is attracted and bent in the direction in which the magnetic force 24 is generated. The deflecting arc bent in the direction of the plate 2a by the action of the magnetic force 24 is stably and continuously maintained, and the wire melting transition is also stable, so that welding can be performed satisfactorily. Similarly, since the arc deflection direction is stabilized by the above-described magnetic force 24 action also in other welding locations 3b having different postures, good welding can be performed.
[0034]
FIG. 7 is an example in which the appropriate condition margin in the steel column welding described above is examined, and the welding torch position Y (wire target position) and the joint gap G are determined by combining the plate 2a with a wall thickness greater than that of the long column member 1a. The determination result of the quality of welding when changed is shown. The welding conditions are as shown in the figure, and a weaving operation for swinging the welding torch is also performed. The symbol “◯” indicates good weld appearance and penetration shape, the symbol “×” indicates poor appearance due to partial melting or melting, and the symbol “Δ” indicates poor penetration shape. In the case of the welded joint shown in FIG. 7, the intersection position of the welded joint is the intersection of the surface of Y = 0 and the surface of the long column member on the welding torch side. The range where good welding results can be obtained is in the region where the wire target position is shifted (-1.5 ≧ Y ≧ 0 mm) to the thick plate side that needs to be accelerated, and the joint with the thin column side It shows that the gap G is also allowable up to 0.5 mm. In this way, by shifting the target position of the welding torch to the thick plate side of the joint and performing arc welding with a weaving operation that swings the welding torch from side to side, stirring of the molten pool and melting of the welded portion can be achieved. As a result, welding defects such as blow holes and burn-through can be prevented, and at the same time, the tolerance of conditions can be increased, and welding results with a uniform penetration shape and good quality can be obtained.
[0035]
FIG. 8 shows a third embodiment of the present invention. The present embodiment is an example in which an overlapping plate member 2b, which is a small article member, is attached to the upper surface of a flat plate-like long member 1 by welding a fillet-like welded portion 3c. (1) in FIG. 8 is a perspective view showing a schematic shape of a joint member, a welding location, and a target position of a welding torch, and (2) in FIG. 8 is a plan view showing a current path generated by welding and a magnetic blowing direction of an arc. 8 (3) is a cross-sectional view showing a bead cross-sectional shape 30 of the lap weld. In the figure, the welding control device, the welding power source, the welding robot, and the torch side feeding cable are omitted, but the welding torch 16 is mounted on the welding robot and connected to the welding power source by the torch side feeding cable. The member-side power supply cable 5 for supplying power from the welding power source to the joint member side is located at an upper position near the center of the long member 1 that is separated from the welding plate 3c from the welding point 3c to the side opposite to the overlap plate member 2b ( It can be installed in the lower position).
[0036]
In this example, the plate thickness t on the long member 1 side. ₁ Is the thickness t of the overlapping plate member 2b ₂ Thicker (t ₁ > t ₂ Therefore, the target position of the welding torch 16 (welding wire 17) is moved to the long member 1 side. ₂ Welded with a shift only. As shown in (2) of FIG. 8, the direction of the magnetic force 24 acting on the arc by the current flowing in the arc welding is a direction in which the arc is deflected toward the non-powered overlapping plate member 2 b, and the welding current flows through the long member 1. Since the current path 22 of the current is stable in the illustrated path, the direction of the magnetic force 24 is also stabilized in the illustrated direction. For this reason, as described above, the arc being welded is attracted in the acting direction of the magnetic force 24 and is stably held. Accordingly, the arc deflected by the magnetic force 24 in the direction of the overlapping plate member 2b is moved to the thick long member 1 side by moving the target position of the welding wire 17 by the torch position shifting function. ₂ By performing the welding only by shifting, melting on the long member 1 side was promoted, and good penetration results could be obtained.
[0037]
9 and 10 show a fourth embodiment of the present invention. The present embodiment is an example in which flanges 2c, which are small article members, are attached and welded to the left and right end surfaces of a long cylindrical member 1b having a cylindrical structure. FIG. 10 (1) shows a welded portion where a part of the joint member is enlarged and a target position of the welding torch, and FIG. 10 (2) shows a cross-sectional view of the bead cross-sectional shape of the welded portion. . The long cylindrical member 1b is mounted on a rotating roller 32 disposed in the rotation driving device 31, and a circumferential surface thereof is driven by the rotating roller 32 and is rotated about an axis line as a rotation axis. A movable power feeder 33 is installed at an upper position near the center of the long cylindrical member 1b (an intermediate position between flanges attached to both ends), and the negative electrode of the movable power feeder 33 and a welding power source (not shown) is fed on the member side. Connected by a cable 5. The movable power feeder 33 supplies power while sliding to the rotating long cylindrical member 1b, and stays at the upper position even when the long cylindrical member 1b rotates. The welding torch 16 is mounted on a welding robot (not shown), and a torch side power supply cable 6 for supplying power from a positive electrode of a welding power source (not shown) to the welding wire 17 at the tip of the torch is connected.
[0038]
The flanges 2c attached to the left and right end surfaces of the long cylindrical member 1b are attached by welding of fillet joints formed by the surfaces facing each other and the outer peripheral surface of the cylindrical portion of the long cylindrical member 1b. The operation of welding the flange 2c is automatically performed in synchronism with the rotation drive device 31 based on teaching data such as a welding position and welding conditions input in advance. The target position of the welding wire 17 is the thickness t of the flange 2c. ₂ S on the long cylindrical member 1b side which is thicker ₂ It is set to the position shifted only by. Welding is also performed by adding a weaving operation that swings the welding torch 16 in the left-right direction orthogonal to the welding line direction.
[0039]
In the present embodiment, the path of the welding current flowing through the long cylindrical member 1b during welding is stabilized by the current path 22 shown in FIG. As a result, the direction of the magnetic force acting on the welding arc by the welding current is stabilized in the direction in which the arc is deflected in the direction toward the flange 2c, and the occurrence of welding defects due to fluctuations in the acting direction of the arc magnetic blowing phenomenon is suppressed.
[0040]
As described above, the magnetic field generated by the arc welding current and the direction in which the magnetic force 24 due to the arc magnetic blowing phenomenon acts are stabilized in the flange 2c side direction, and the deflection arc is shifted to the long cylindrical member 1b side by an appropriate amount. By performing arc welding in the weaving operation, melting on the thick member side is promoted, and a welding result with a good penetration shape can be obtained as shown in (2) of FIG.
[0041]
FIG. 11 shows an example of a condition control block diagram in each of the above embodiments. The vertical axis corresponding to the time on the horizontal axis shows the welding current Ia (A), the wire feed speed Wf (m / min), and the welding voltage Ea. (V), welding speed Vs (mm / min), presence / absence of weaving operation, and control operation of shield gas SG are displayed. The condition numbers (1) to (4) in the figure are output conditions for each process from the welding start point (P1) to the welding end point (P3). Showed. That is, when teaching the welding line position and welding conditions of the joint to be welded (see FIGS. 1, 4, and 8) from the operation box 10 to the welding control device 9, first, the teaching point point of the total length of the welding line is set. (Point) is set at least 2 points on the start side and 1 point or more on the end side. From the welding start point (P1, arc start point) to the steady welding start point (P2), the start part (1), (2), and from this steady welding start point to the end point of steady welding, steady welding Part (3), and after reaching the end point of this steady welding, it is distinguished as a welding end part (4), and predetermined welding conditions (welding conditions described in Table 1) are output at each of the distinguished parts. Set as possible.
[0042]
[Table 1]

For example, here, T ₃ After a time, a welding wire is fed to the welding torch 16 set at the point P1 (wire feed speed Wf1), and a small current Ia1 and a small voltage Ea1 are applied to generate an arc to form a molten pool. Arc starts and T ₁ After the elapse of time, the welding current, voltage, and wire feed speed are increased (Ia2, Ea2, Wf2), and the welding torch travel (welding speed Vs2) and the weaving operation (oscillation width W, cycle f) are started. Then, when the welding torch 16 reaches the point P2 where the steady welding is started, the state is shifted to the steady welding conditions (Ea3, Ia3, Wf3), and the welding state is continued to the welding end point P3. The weaving operation may be started from point P2. After that, when reaching the welding end point P3, the torch traveling and the weaving operation are stopped, and the welding voltage, current, and wire feed speed are decreased (Ea4, Ia4, W4, f4), and the molten pool is reduced and recessed. Smoothing T ₂ Stop arc after time has elapsed. After-flow time T after stopping the arc ₄ After the lapse of time, the shield gas is stopped, the welding torch is moved around and welding is completed.
[0043]
The welding conditions for each process may be taught and set to appropriate values according to the specifications of the structure and welded joint. In this way, the condition control from the start to the end of welding is properly performed, and the direction in which the magnetic action generated by the welding current flowing between the welding wire and the long member and the arc magnetic blowing phenomenon are expressed is welded. By stabilizing the arc in the direction in which the arc in the non-powered small article member is deflected, a high-quality welding result can be obtained over the entire length of the weld from the start to the steady weld and the end.
[0044]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent arc wobbling, arc breakage, disorder of wire melting, etc., and to obtain a welding result with good quality by stable deflection arc and wire melting transition welding, It can contribute to productivity improvement and cost reduction.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a first embodiment of the present invention.
FIG. 2 is a cross-sectional view and a plan view showing details of a portion of the embodiment of FIG.
FIG. 3 is a cross-sectional view showing an example of a bead cross-sectional shape of a welded portion implemented by the welding method shown in FIG. 2;
FIG. 4 is a conceptual diagram showing a second embodiment of the present invention.
5 is a perspective view showing a long column member and a plate shown in FIG. 4; FIG.
6 is a plan view showing a current path and an arc magnetic blowing direction in the embodiment shown in FIG. 4; FIG.
FIG. 7 is a graph showing an example of an appropriate wire aiming position corresponding to a joint gap when the plate thickness is larger than the plate thickness of the long column member in the second embodiment of the present invention. .
FIG. 8 is a perspective view, a plan view, and a sectional view showing a third embodiment of the present invention.
FIG. 9 is a perspective view showing a fourth embodiment of the present invention.
10 is a cross-sectional view showing a torch aiming position and a bead cross-sectional shape of a weld in the embodiment shown in FIG. 9;
FIG. 11 is a time chart showing an example of welding condition control in the embodiment of the present invention.
[Explanation of symbols]
1 Long member
1a Long column member
1b Long cylindrical member
2 Small article members
2a plate
2b Overlapping plate member
2c flange
3, 3a, 3b, 3c welding location
4 Welding power source
5 Member-side power supply cable
6 Torch side power supply cable
8 Interface
9 Welding control device
10 Operation box
11 Welding robot
12 Control cable
13 Wire feeder
15 Torch cable
16 Welding torch
17 Welding wire
20 Position where the member-side power supply cable is connected
22 Current path
23 Magnetic field lines
24 Magnetic force
25 Welding direction,
26 Rotating drum
27 Column fixing stand
28 Column clamp feeder
29 Plate fixing jig
30 Bead cross-sectional shape
31 Rotation drive
32 Rotating roller
33 Movable power feeder

Claims

Two sets of fillet joints or laps to be welded by disposing two second members having a shape shorter than the first member on opposite positions or both end surfaces of the upper surface of the long first member, respectively. In an automatic welding method in which a joint portion is formed at each of the upper surface position or both end surface positions of the first member, and arc welding of the joint portion is performed using a welding torch and a welding wire connected to one polarity of a welding power source,
A power supply cable connected to the other polarity of the welding power source is fixedly connected to one place on the upper surface or the lower surface of the first member at an intermediate position sandwiched between the two sets of fillet joint portions or lap joint portions, The arcs deflected by a magnetic force generated by a welding current flowing in a welding portion of the first member that is fed during welding are deflected toward the second member, and the joint portions are arc welded, respectively. Automatic welding method to do.