JP3741402B2

JP3741402B2 - Two-electrode electrogas welding method

Info

Publication number: JP3741402B2
Application number: JP28216298A
Authority: JP
Inventors: 黒盈昭乙; 垣忠彦宮; 江敦忠本; 井浩辻; 田昌宏太
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Ltd
Priority date: 1998-10-05
Filing date: 1998-10-05
Publication date: 2006-02-01
Anticipated expiration: 2018-10-05
Also published as: JP2000107893A

Description

【０００１】
【発明の属する技術分野】
本発明は、２電極エレクトロガス溶接用裏当材および溶接方法に係り、特に、厚鋼板の２電極エレクトロガス溶接において優れた溶接作業性と良好な溶け込み形状が得られる２電極エレクトロガス溶接方法に関する。
【０００２】
【従来の技術】
立向自動溶接方法としてエレクトロガス溶接が、造船，円筒形貯油タンクをはじめ鉄骨，橋梁，重電機器，製鉄設備等の鋼壁溶接に主として用いられている。エレクトロガス溶接において、電圧，電流を上昇して入熱を上げると、高能率であるが、高張力鋼の溶接には溶接入熱量が大きいために、溶接金属や母材熱影響部等の切欠靭性を劣化させる要因となる。
【０００３】
特に最近は、熱影響部の健全性を保つために低入熱溶接が強く要求される傾向にあり、このような要求に対して、細径フラックス入りワイヤを用い板厚方向に高速振動でアーク点を移動させるエレクトロガス溶接は、開先断面積を極力小さくした狭開先溶接を、低入熱で高能率に行えるため、鋼板の立向溶接に適している。
【０００４】
このようなエレクトロガス溶接を行う装置の概略を説明すると、垂直に立てられ隣り合う２鋼板の間の開先の裏面に、水冷銅当金あるいは固形裏当材を当接し、表面には水冷の摺動銅当金を当てて、この摺動銅当金の溝（開先に対向）と開先で囲まれる空間に、扁平な溶接トーチを挿入し、これを板厚方向に高速振動させながら、溶接トーチを通して細径フラックス入りワイヤを該空間に連続的に供給し、かつ溶接トーチおよび摺動銅当金を連続的に上方に駆動しながら、開先の立向溶接を行う。
【０００５】
前記エレクトロガス溶接が適用できる板厚（開先の深さ）は、６０ｍｍ程度までであり、板厚がこれ以上の極厚鋼板になると、開先部の端縁部に溶け込み不良が生じるなど、部分的な溶け込み不良を生じやすい。
【０００６】
そこで、本発明者らは、溶け込み不良等の欠陥がなくかつ高能率な、極厚鋼板の溶接が可能な２電極エレクトロガス溶接装置を提案した（特開平１０−１１８７７１号公報）。
【０００７】
【発明が解決しようとする課題】
前記２電極エレクトロガス溶接装置での極厚鋼板の溶接は、アークの安定性および溶接金属の切欠靭性の確保から、細径フラックス入りワイヤが用いられる。しかし、フラックス入りワイヤの溶融によって生成されるスラグは、摺動銅板側ワイヤのアークによってせき止められ、摺動銅板のスラグ逃がしから排出できず、溶融プールの摺動銅板側電極と裏当材側電極との間（ワイヤ極間）、および、裏当材側電極と裏当材の間、にスラグが滞在してスラグ跳ねが発生する。跳ねたスラグは、開先面および溶接トーチに付着して、開先幅が狭い裏当材側で電極が接触して溶接を中断したり、溶融プールにスラグが多く溜まって、溶接アーク熱が開先面に十分伝わらず、融合不良の発生や、良好な裏波ビードが得られない、という問題があった。
【０００８】
本発明は、極厚鋼板の２電極エレクトロガス溶接において、スラグ跳ねがなくアークが安定して溶接作業性が良好で、裏波ビードが良好で融合不良のない健全な溶接部が得られるとともに、溶接を中断することなく高能率に溶接できる、２電極エレクトロガス溶接方法を提供することを目的とする。
【０００９】
【課題を解決するための手段】
（１）厚鋼板の２電極エレクトロガス溶接において、開先形状が開先ギャップを有するＶ開先の、板厚が４０〜１００ｍｍの鋼板の開先裏面に、開先幅方向ｘの幅Ｗ１が裏面側開先ギャップよりも広いスラグ溜まり用の第１の溝さらに該第１の溝の中央部に幅Ｗ２が前記幅Ｗ１よりも狭く裏面側開先ギャップよりも広く第１の溝の底面から前記板厚の方向ｙに堀り下げた裏ビード形成用の第２の溝を設けた、前記開先幅方向ｘおよび板厚の方向ｙに直交する垂直方向ｚに延びる固形裏当材を当接して、前記開先内で前記板厚の方向ｙに分布する２電極を該板厚の方向ｙに揺動駆動して裏面側開先ギャップ側の溶融スラグを前記固形裏当材のスラグ溜まり用の第１の溝に流出させながら溶接することを特徴とする２電極エレクトロガス溶接方法。
【００１０】
（２）裏面側開先ギャップの開先幅方向の幅は８〜１５ｍｍ、第１の溝の幅Ｗ１は２０〜４５ｍｍ、かつ、第２の幅Ｗ２は１２〜２３ｍｍであることを特徴とする上記（１）に記載の２電極エレクトロガス溶接方法。
【００１１】
（３）第１の溝は深さ１．０〜２．０ｍｍ、かつ、第２の溝は深さが第１の溝底面から１．０〜２．０ｍｍであることを特徴とする上記（１）又は（２）記載の２電極エレクトロガス溶接方法。
【００１２】
なお、上記裏当材とは、金属酸化物や弗化物等を焼成または焼結した固形裏当材をいう。
【００１３】
【発明の実施の形態】
図１に、２電極エレクトロガス溶接装置を用いて溶接する状態の模式図を示す。溶接トーチ２の裏当材３側に裏当材側電極５を、溶接部をシールドするシールドガスのガス供給口９を有する摺動銅板１０側に摺動鋼板側電極４を備え、ワイヤ極間距離１１を一定に保ち、かつ裏当材３と摺動銅板１０との間で電極を、揺動方向１に示すように、溶接開先の裏面と表面間を揺動しながら、アーク６により溶接金属８を形成して溶接する。
【００１４】
溶融スラグ７は、摺動銅板１０側のスラグ逃がし１２より容易に逃がすことができるが、溶接トーチ２のト−チ間や裏当材３側の溶融スラグ７は、外部に逃がすことは困難で、スラグ跳ねが生じる。
【００１５】
したがって、２電極エレクトロガス溶接を作業性良く、無欠陥で高能率に実施するには、溶接トーチ２のト−チ間や裏当材３側の溶接スラグ７の量をコントロールする必要がある。
【００１６】
図２に、本発明の２電極エレクトロガス溶接用の裏当材３を、また、図３に、該裏当材３を開先裏面１６に当接した例を、それぞれ示す。裏当材３表面の長手方向（ｚ方向）中央部に、２段溝（１３，１４）を設け、２段溝はスラグ溜まり用の第１の溝１３、第１の溝１３の中央部に第１の溝１３から堀り下げた裏ビード形成用の第２の溝１４を設けている。
【００１７】
鋼板１５の板厚Ｔは、２電極の溶接トーチ２で溶接可能でかつ高温割れの生じない板厚Ｔ４０ｍｍ以上とし、溶接速度の低下に伴う溶接入熱量増での溶接部の切欠靭性低下から１００ｍｍ以下として、開先形状は開先ギャップを有するＶ開先で、溶接入熱量を低くするために溶接トーチ２のセット可能な範囲で狭開先とする。
【００１８】
なお、裏当材３当接側の開先ギャップは８〜１５ｍｍ、摺動銅板１０側の開先ギャップは２０〜３０ｍｍ程度であることが、溶接作業性および溶接能率から好ましい。
【００１９】
このように構成された２電極エレクトロガス用裏当材３を用いる本発明の溶接方法においては、フラックス入りワイヤの溶融によって生成された裏当材側電極５と裏当材３間の溶融スラグ７は、第１の溝１３に流出して溶融プールに溜まることがない。また、溶接トーチ２間（ワイヤ４／５間）の溶融スラグ７は、溶融スラグ量の少ない摺動銅板１０側および裏当材３側に流出するので溶融プールに溜まることがない。したがって、スラグ跳ねが生じずスラグが溶接トーチ２または開先面に付着することがないので、連続して安定した溶接ができる。さらに、溶接熱が開先面に十分伝わるので、融合不良が生じることがない。
【００２０】
なお、裏当材３の開先裏面１６への当接は、図３に示すように、アルミ箔，亜鉛箔などの金属箔の耐熱テープ１７に接着剤を付けたもの、あるいは裏当材を開先裏面に押し付けるマグネットまたは拘束用治具で行う。また、裏当材３の開先裏面１６への当接を良好とするために、裏当材３と開先裏面１６との間にガラス繊維シートを挾んでも良い。
【００２１】
裏当材３の第１の溝１３の深さｔ１は、１．０〜２．０ｍｍとする。第１の溝１３の深さｔ１が１．０ｍｍ未満であると、フラックス入りワイヤの溶融によって生成された裏当材側電極５と裏当材３間の溶融スラグ７が流出しきれず、また、第１の溝１３の深さｔ１が１．０ｍｍ未満で幅を広くしても溶融スラグ７は開先裏面１６と第１の溝間１３に流れていかず、溶接の進行に伴って溶融スラグ７が増加してスラグ跳ねが発生し開先面および溶接トーチ２に付着して、開先幅が狭い裏当材３側で裏当材側電極５が開先壁に接触して溶接が中断したり、溶接アーク熱が開先面に十分伝わらず、融合不良が発生するようになる。
【００２２】
第１の溝１３の深さｔ１が２．０ｍｍを超えると、溶融スラグ７は第１の溝１３に流出して溶融プールに溜まらずスラグ跳ねがなく良好であるが、図４の（ａ）に示すように開先裏面１６に第１の溝部と第２の溝１４部に溶接金属が突出して、裏ビードは二段ビード１８となる。
【００２３】
裏当材３の第１の溝１３の幅ｗ１は、２０〜４５ｍｍとする。第１の溝１３の幅ｗ１が２０ｍｍ未満であると、フラックス入りワイヤの溶融によって生成された裏当材側電極５と裏当材３間の溶融スラグ７が流出しきれずに、溶接の進行に伴って溶融スラグ７が増加してスラグ跳ねが発生し開先面および溶接トーチ２に付着して、開先幅が狭い裏当材３側で裏当材電極５が開先壁に接触して溶接が中段したり、溶接アーク熱が開先面に十分伝わらず、融合不良が発生するようになる。第１の溝１３の幅ｗ１が４５ｍｍを超えると、開先裏面１６に第１の溝１３部と第２の溝１４部に溶接金属が突出して二段ビード１８となる。
【００２４】
裏当材３の第２の溝１４の深さｔ２は、第１の溝１３底面から１．０〜２．０ｍｍ、幅ｗ２は１２〜２３ｍｍとする。第２の溝１４の深さｔ２が第１の溝１３の底面から１．０未満であると、溶融スラグ７が多いので第２の溝１４までスラグで被われて、図４の（ｂ）に示すように、裏ビードが形成されない場合がある。第２の溝１４の幅ｗ２が１２ｍｍ未満であると、裏ビードが良好に形成されず図４の（ｃ）に示すように、アンダーカット１９が生じる。第２の溝１４の深さｔ２が、第１の溝１３の底面から２ｍｍを超えると、または第２の溝１４の幅ｗ２が２３ｍｍを超えると、図４の（ｄ）に示すように裏ビードが出すぎてオーバーラップ２０が生じる。
【００２５】
【実施例】
以下、実施例により本発明をさらに詳細に説明する。表１に示す各寸法の裏当材を試作した。溶接は、表２に示す成分，板厚の鋼板および開先形状として、同表に示す溶接条件で溶接長１０００ｍｍを２電極エレクトロガス溶接装置で溶接した。なお、溶接ワイヤ４，５は、ＪＩＳＺ３３１９ＹＦＥＧ−４２Ｃ１．６ｍｍ径のフラックス入りワイヤを用いた。
【００２６】
溶接中のアーク状態および溶接終了後の裏ビード形状の観察をした後、マクロ試験片を各１０個採取して溶け込み形状を調べた。それらの結果を表１にまとめて示す。
【００２７】
【表１】

【００２８】
【表２】

【００２９】
表１中、試験Ｎｏ．１〜６が本発明の実施例、試験Ｎｏ．７〜１４が比較例である。本発明の実施例である試験Ｎｏ．１〜６は、２段溝を設けた裏当材形状の深さおよび幅が適正であるので、フラックス入りワイヤの溶融によって生成した溶融スラグ７は、裏当材３の第１の溝１３に流出してコントロールされて溶融プールに溜まることがないので、スラグ跳ねが生じず溶接トーチ２や開先面に付着することがないので、溶接熱が開先面に十分伝わって最後まで融合不良が生じることなく溶接できた。また、裏ビード形状も良好であるなど極めて満足な結果であった。
【００３０】
比較例中の試験Ｎｏ．７は、裏当材３の第１の溝１３の深さｔ１が小さいので、また、試験Ｎｏ．９は、第１の溝１３の幅ｗ１が小さいので、いずれも生成スラグ７が溶融プールに溜まりスラグ跳ねが生じ、試験Ｎｏ．７は溶接長６５０ｍｍで、試験Ｎｏ．９は溶接長７００ｍｍで、跳ねたスラグが開先面および溶接トーチ２に付着蓄積して、溶接トーチ２の揺動が困難となったので溶接を中止した。また、マクロ断面を調べた結果溶融不良もあった。
【００３１】
試験Ｎｏ．８は、第１の溝１３の深さｔ１が大きいので、また、試験Ｎｏ．１０は、第１の溝１３の幅ｗ１が大きいので、いずれも生成スラグ７の流出は良好でスラグ跳ねは生じず溶接中断および溶融不良は生じなかったが、裏ビードが二段ビードとなった。
【００３２】
試験Ｎｏ．１１は、第２の溝１４の深さｔ２が小さいので、裏ビードが形成されなかった。
【００３３】
試験Ｎｏ．１２は、第２の溝１４の深さｔ２が大きく、また、試験Ｎｏ．１４は、第２の溝１４の幅ｗ２が大きいので、いずれも裏ビードにオーバラップが生じた。
【００３４】
試験Ｎｏ．１３は、第２の溝１４の幅ｗ２が小さいので、アンダーカットが生じた。
【００３５】
【発明の効果】
以上のように本発明の２電極エレクトロガス溶接方法によれば、スラグ跳ねがなくアークが安定して溶接作業性が良好で、裏波ビードが良好で融合不良のない健全な溶接部が得られるとともに、溶接を中断することなく高能率に溶接できる。
【図面の簡単な説明】
【図１】２電極エレクトロガス溶接装置を用いて溶接する状態の模式図であり、開先の縦断面を示す。ただし摺動銅板１０は側面を示す。
【図２】本発明の２電極エレクトロガス溶接で用いる裏当材を示す平面図である。
【図３】本発明の２電極エレクトロガス溶接で用いる裏当材を開先裏面に当接した例を示す平面図である。
【図４】（ａ），（ｂ），（ｃ）および（ｄ）は、２電極エレクトロガス溶接方法によって形成された各種裏ビードの形状を示す平面図である。
【符号の説明】
１：揺動方向２：溶接トーチ
３：裏当材４：摺動銅板側電極
５：裏当材側電極６：アーク
７：溶融スラグ８：溶接金属
９：ガス供給口１０：摺動銅板
１１：ワイヤ極間距離１２：スラグ逃がし
１３：第１の溝１４：第２の溝
１５：鋼板１６：開先裏面
１７：耐熱テープ１８：二段ビード
１９：アンダーカット２０：オーバーラップ[0001]
BACKGROUND OF THE INVENTION
The present invention 2 relates to the electrode electro-gas welding backing strip and welding methods, in particular, the thickness good weldability and good penetration 2 electrode electro gas soluble shape is obtained against the second electrode electro-gas welding of steel plates Regarding the method.
[0002]
[Prior art]
As a vertical automatic welding method, electrogas welding is mainly used for steel wall welding of shipbuilding, cylindrical oil storage tanks, steel frames, bridges, heavy electrical equipment, steelmaking facilities, and the like. In electrogas welding, increasing the heat input by increasing the voltage and current results in high efficiency. However, because welding heat input is large in welding high-strength steel, notches such as weld metal and base metal heat-affected areas are cut off. It becomes a factor which degrades toughness.
[0003]
Recently, in order to maintain the soundness of the heat-affected zone, low-heat-input welding has tended to be strongly demanded. Electrogas welding for moving points is suitable for vertical welding of steel sheets because narrow groove welding with a groove cross-sectional area as small as possible can be performed with low heat input and high efficiency.
[0004]
An outline of an apparatus for performing such electrogas welding will be described. A water-cooled copper metal or a solid backing material is brought into contact with the back surface of a groove between two vertically-adjacent steel plates, and the surface is water-cooled. Applying a sliding copper alloy, a flat welding torch is inserted into the space surrounded by the groove (opposite the groove) and the groove of this sliding copper alloy, and this is vibrated at high speed in the plate thickness direction. The vertical welding of the groove is performed while continuously supplying the small-diameter flux-cored wire to the space through the welding torch and continuously driving the welding torch and the sliding copper plating upward.
[0005]
The plate thickness (groove depth) to which the electrogas welding can be applied is up to about 60 mm, and when the plate thickness is an extra-thick steel plate of more than this, a poor melting occurs at the edge portion of the groove portion, etc. Prone to partial penetration failure.
[0006]
Accordingly, the present inventors have a and high efficiency without defects such as poor penetration welding of very thick steel plate has proposed possible two electrode electro-gas welding device (JP-A 10-118771 JP).
[0007]
[Problems to be solved by the invention]
For the welding of an extremely thick steel plate using the two-electrode electrogas welding apparatus, a thin flux cored wire is used in order to ensure the stability of the arc and the notch toughness of the weld metal. However, the slag generated by the melting of the flux-cored wire is blocked by the arc of the sliding copper plate side wire and cannot be discharged from the slag relief of the sliding copper plate, and the sliding copper plate side electrode and backing material side electrode of the molten pool Slag stays between the wire (between the wire electrodes) and between the backing material side electrode and the backing material, and slag splash occurs. The splashed slag adheres to the groove surface and the welding torch, and the electrode comes into contact with the backing material side with a narrow groove width to interrupt welding, or a lot of slag accumulates in the molten pool, causing welding arc heat to be generated. There was a problem that the groove surface was not sufficiently transmitted, resulting in poor fusion, and a good back bead could not be obtained.
[0008]
In the present invention, in the two-electrode electrogas welding of an extra-thick steel plate, there is no slag splash, the arc is stable, the welding workability is good, the back bead is good, and a healthy weld with no poor fusion is obtained. It can be welded with high efficiency without interrupting the welding, and an object thereof is to provide a two-electrode electro-gas welding how.
[0009]
[Means for Solving the Problems]
(1) In the second electrode electro-gas welding of thick steel plates, a V groove which groove shape having a groove gap, the groove rear surface of the steel plate thickness is 40 to 100 mm, the width W1 of the groove width direction x is The first groove for slag accumulation wider than the back side groove gap, and the width W2 at the center of the first groove is narrower than the width W1 and wider than the back side groove gap from the bottom surface of the first groove. A solid backing material extending in the groove width direction x and the vertical direction z perpendicular to the plate thickness direction y and provided with a second groove for forming a back bead drilled in the plate thickness direction y is applied. In contact therewith, the two electrodes distributed in the plate thickness direction y in the groove are driven to swing in the plate thickness direction y, so that the molten slag on the back side groove gap side is accumulated in the slag reservoir of the solid backing material. first 2 electrode electro-gas welding direction, characterized by welding while the outflow into the groove of use .
[0010]
(2) The width in the groove width direction of the back surface side groove is 8 to 15 mm, the width W1 of the first groove is 20 to 45 mm, and the second width W2 is 12 to 23 mm. The two-electrode electrogas welding method according to (1) above .
[0011]
(3) the first groove depth 1.0~2.0mm and, of the second groove depth is characterized 1.0～2.0M m Der Rukoto from the first groove bottom The two-electrode electrogas welding method according to the above (1) or (2) .
[0012]
The backing material refers to a solid backing material obtained by firing or sintering a metal oxide, fluoride, or the like.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic diagram showing a state of welding using a two-electrode electrogas welding apparatus. A backing material side electrode 5 is provided on the backing material 3 side of the welding torch 2, and a sliding steel plate side electrode 4 is provided on the sliding copper plate 10 side having a gas supply port 9 for shielding gas for shielding the welded portion. While maintaining the distance 11 constant, and the electrode 6 between the backing material 3 and the sliding copper plate 10, as shown in the oscillating direction 1, the arc 6 oscillates between the back surface and the surface of the welding groove. A weld metal 8 is formed and welded.
[0014]
The molten slag 7 can be easily released from the slag relief 12 on the sliding copper plate 10 side, but it is difficult to escape the molten slag 7 between the torches of the welding torch 2 or the backing material 3 side to the outside. Slag splash occurs.
[0015]
Therefore, in order to perform the two-electrode electrogas welding with high workability and high efficiency without defects, it is necessary to control the amount of the welding slag 7 between the torches of the welding torch 2 or the backing material 3 side.
[0016]
Figure 2, the backing material 3 for two electrodes electro-gas welding of the present invention, also in FIG. 3, an example in which contact with the backing strip 3 to groove back surface 16, respectively. A two-step groove (13, 14) is provided at the center of the surface of the backing material 3 in the longitudinal direction (z direction), and the two-step groove is formed at the center of the first groove 13 and the first groove 13 for slag accumulation. A second groove 14 for forming a back bead that is dug down from the first groove 13 is provided.
[0017]
The plate thickness T of the steel plate 15 can be welded by the two-electrode welding torch 2 and has a thickness T of 40 mm or more that does not cause high temperature cracking. In the following, the groove shape is a V groove having a groove gap, and the groove shape is narrow within a range in which the welding torch 2 can be set in order to reduce the welding heat input.
[0018]
In addition, it is preferable from welding workability | operativity and welding efficiency that the groove gap by the side of the backing material 3 is 8-15 mm, and the groove gap by the side of the sliding copper plate 10 is about 20-30 mm.
[0019]
Molten slag between the welding in the process, backing material side electrode 5 and the backing material 3 which has been produced by melting of the flux cored wire of the thus constructed 2 the invention the back electrode electro-gas Ru with those timber 3 7 does not flow out into the first groove 13 and accumulate in the molten pool. Moreover, since the molten slag 7 between the welding torches 2 (between the wires 4/5) flows out to the sliding copper plate 10 side and the backing material 3 side with a small amount of molten slag, it does not accumulate in the molten pool. Therefore, slag splash does not occur and slag does not adhere to the welding torch 2 or the groove surface, so that continuous and stable welding can be performed. Furthermore, since welding heat is sufficiently transmitted to the groove surface, no fusion failure occurs.
[0020]
Na us, abutment against the groove rear surface 16 of the

backing

material 3, as shown in FIG. 3, as attached aluminum foil, an adhesive heat tape 17 of metallic foil, such as zinc foil, or backing material With a magnet or a restraining jig that presses against the back of the groove. In addition, a glass fiber sheet may be sandwiched between the backing material 3 and the groove back surface 16 in order to improve the contact of the backing material 3 with the groove back surface 16.
[0021]
The depth t1 of the first groove 13 of the backing material 3 is 1.0 to 2.0 mm. When the depth t1 of the first groove 13 is less than 1.0 mm, the molten slag 7 between the backing material side electrode 5 and the backing material 3 generated by melting the flux-cored wire cannot flow out, and Even if the depth t1 of the first groove 13 is less than 1.0 mm and the width is widened, the molten slag 7 does not flow between the groove back surface 16 and the first groove 13, and the molten slag 7 is moved along with the progress of welding. Slag splash occurs and adheres to the groove surface and the welding torch 2, the backing material side electrode 5 contacts the groove wall on the backing material 3 side where the groove width is narrow, and welding is interrupted. Otherwise, the welding arc heat is not sufficiently transmitted to the groove surface, resulting in poor fusion.
[0022]
When the depth t1 of the first groove 13 exceeds 2.0 mm, the molten slag 7 flows out into the first groove 13 and does not accumulate in the molten pool and is good without slag splashing. As shown, the weld metal protrudes from the groove rear surface 16 to the first groove portion and the second groove 14 portion, and the back bead becomes a two-stage bead 18.
[0023]
The width w1 of the first groove 13 of the backing material 3 is 20 to 45 mm. If the width w1 of the first groove 13 is less than 20 mm, the molten slag 7 between the backing material side electrode 5 and the backing material 3 generated by melting the flux-cored wire cannot flow out, and the welding progresses. Along with this, the molten slag 7 increases and slag splash occurs, adheres to the groove surface and the welding torch 2, and the backing material electrode 5 contacts the groove wall on the backing material 3 side where the groove width is narrow. Welding becomes middle stage or welding arc heat is not sufficiently transmitted to the groove surface, resulting in poor fusion. When the width w1 of the first groove 13 exceeds 45 mm, the weld metal protrudes from the groove back surface 16 to the first groove 13 portion and the second groove 14 portion to form a two-stage bead 18.
[0024]
The depth t2 of the second groove 14 of the backing material 3 is 1.0 to 2.0 mm from the bottom surface of the first groove 13 and the width w2 is 12 to 23 mm. When the depth t2 of the second groove 14 is less than 1.0 from the bottom surface of the first groove 13, since the molten slag 7 is large, the second groove 14 is covered with the slag, and FIG. As shown in FIG. 2, the back bead may not be formed. If the width w2 of the second groove 14 is less than 12 mm, the back bead is not formed well, and an undercut 19 occurs as shown in FIG. When the depth t2 of the second groove 14 exceeds 2 mm from the bottom surface of the first groove 13 or when the width w2 of the second groove 14 exceeds 23 mm, as shown in FIG. The bead comes out too much and the overlap 20 arises.
[0025]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. Trial backing materials having the dimensions shown in Table 1 were produced. Welding was performed using a two-electrode electrogas welding apparatus with a welding length of 1000 mm under the welding conditions shown in the table, with the components shown in Table 2, the steel plate having the thickness, and the groove shape. The

welding wires

4 and 5 were JIS Z3319 YFEG-42C 1.6 mm diameter flux cored wires.
[0026]
After observing the arc state during welding and the back bead shape after the end of welding, ten macro test pieces were sampled to examine the penetration shape. The results are summarized in Table 1.
[0027]
[Table 1]

[0028]
[Table 2]

[0029]
In Table 1, test no. 1 to 6 are examples of the present invention, test Nos. 7 to 14 are comparative examples. Test No. which is an example of the present invention. Since the depth and width of the backing material shape provided with the two-step grooves are appropriate for Nos. 1 to 6, the molten slag 7 generated by the melting of the flux-cored wire is formed in the first groove 13 of the backing material 3. Since it does not flow out and is controlled and does not accumulate in the molten pool, slag splash does not occur and it does not adhere to the welding torch 2 or the groove surface, so that the welding heat is sufficiently transmitted to the groove surface, resulting in poor fusion until the end. We were able to weld it without causing it. Also, the back bead shape was good and the results were very satisfactory.
[0030]
Test No. in the comparative example. 7 has a small depth t1 of the first groove 13 of the backing material 3, and the test No. No. 9, since the width w1 of the first groove 13 is small, the generated slag 7 accumulates in the molten pool and slag splash occurs. No. 7 has a weld length of 650 mm. No. 9 has a weld length of 700 mm, and the slag bounced adheres and accumulates on the groove surface and the welding torch 2, making it difficult to swing the welding torch 2, so welding was stopped. Further, as a result of examining the macro cross section, there was a melting failure.
[0031]
Test No. No. 8 has a large depth t1 of the first groove 13, and the test No. No. 10, since the width w1 of the first groove 13 was large, the outflow of the generated slag 7 was good and no slag splash occurred, no welding interruption and poor melting occurred, but the back bead became a two-stage bead .
[0032]
Test No. In No. 11, since the depth t2 of the second groove 14 was small, the back bead was not formed.
[0033]
Test No. 12, the depth t2 of the second groove 14 is large. In No. 14, since the width w2 of the second groove 14 was large, the back bead overlapped.
[0034]
Test No. No. 13 had an undercut because the width w2 of the second groove 14 was small.
[0035]
【The invention's effect】
According to the two electrode electro-gas welding how of the present invention as described above, the arc without slag splashing is has good weldability stable, the sound welds without good fusion poor penetration bead As well as being obtained, it is possible to weld with high efficiency without interrupting welding.
[Brief description of the drawings]
FIG. 1 is a schematic view of a state where welding is performed using a two-electrode electrogas welding apparatus, and shows a longitudinal section of a groove. However, the sliding copper plate 10 shows a side surface.
It is a plan view showing a backing strip that are use in two-electrode electro-gas welding of the present invention; FIG.
3 is a plan view showing an example in which contact with a backing material that are use in two-electrode electro-gas welding groove back surface of the present invention.
4 (a), (b), (c) and (d) are plan views showing the shapes of various back beads formed by a two-electrode electrogas welding method. FIG.
[Explanation of symbols]
1: Swing direction 2: Welding torch 3: Backing material 4: Sliding copper plate side electrode 5: Backing material side electrode 6: Arc 7: Molten slag 8: Weld metal 9: Gas supply port 10: Sliding copper plate 11 : Distance between wire poles 12: Slag relief 13: First groove 14: Second groove 15: Steel plate 16: Groove back surface 17: Heat-resistant tape 18: Two-stage bead 19: Undercut 20: Overlap

Claims

厚鋼板の２電極エレクトロガス溶接において、開先形状が開先ギャップを有するＶ開先の、板厚が４０〜１００ｍｍの鋼板の開先裏面に、開先幅方向ｘの幅Ｗ１が裏面側開先ギャップよりも広いスラグ溜まり用の第１の溝さらに該第１の溝の中央部に幅Ｗ２が前記幅Ｗ１よりも狭く裏面側開先ギャップよりも広く第１の溝の底面から前記板厚の方向ｙに堀り下げた裏ビード形成用の第２の溝を設けた、前記開先幅方向ｘおよび板厚の方向ｙに直交する垂直方向ｚに延びる固形裏当材を当接して、前記開先内で前記板厚の方向ｙに分布する２電極を該板厚の方向ｙに揺動駆動して裏面側開先ギャップ側の溶融スラグを前記固形裏当材のスラグ溜まり用の第１の溝に流出させながら溶接することを特徴とする２電極エレクトロガス溶接方法。In two-electrode electro-gas welding of thick steel plates, a V groove having a groove shape groove gap, the groove rear surface of the steel plate thickness is 40 to 100 mm, the width W1 of the groove width direction x is the back side opening The first groove for storing the slag wider than the front gap, and the width W2 at the center of the first groove is narrower than the width W1 and wider than the back-side groove, and the plate thickness from the bottom surface of the first groove. A solid backing material extending in the vertical direction z perpendicular to the groove width direction x and the plate thickness direction y, provided with a second groove for forming a back bead drilled in the direction y of The two electrodes distributed in the plate thickness direction y in the groove are driven to swing in the plate thickness direction y, so that the molten slag on the back side groove gap side is used for the slag accumulation of the solid backing material . A two-electrode electrogas welding method, wherein welding is performed while flowing into one groove.

裏面側開先ギャップの開先幅方向の幅は８〜１５ｍｍ、第１の溝の幅Ｗ１は２０〜４５ｍｍ、かつ、第２の幅Ｗ２は１２〜２３ｍｍであることを特徴とする請求項１に記載の２電極エレクトロガス溶接方法。 The width in the groove width direction of the back surface side groove is 8 to 15 mm, the width W1 of the first groove is 20 to 45 mm, and the second width W2 is 12 to 23 mm. 2 electrode electro-gas welding method according to.

第１の溝は深さ１．０〜２．０ｍｍ、かつ、第２の溝は深さが第１の溝底面から１．０〜２．０ｍｍであることを特徴とする請求項１又は請求項２記載の２電極エレクトロガス溶接方法。The first groove depth 1.0 to 2.0 mm, and, according to claim 1 second grooves which are deep and wherein 1.0～2.0M m Der Rukoto from the first groove bottom Alternatively, the two-electrode electrogas welding method according to claim 2 .