JP2010214459A - Method for producing welded steel pipe - Google Patents
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本発明は、石油や天然ガスの採掘および輸送に使用される高強度高靱性な溶接鋼管、特にシーム溶接部の余盛高さが低く均一な溶接鋼管の製造方法に関する。 The present invention relates to a high strength and high toughness welded steel pipe used for mining and transportation of oil and natural gas, and more particularly to a method for producing a uniform welded steel pipe with a low surplus height at a seam weld.
近年、石油や天然ガスの採掘および輸送に使用されるラインパイプの重要度がますます高まり、輸送効率向上を狙った高圧操業で使用される高強度高靱性ラインパイプを安定して供給することが強く要望されている。 In recent years, the importance of line pipes used for oil and natural gas mining and transportation has increased, and the stable supply of high-strength, high-toughness line pipes used in high-pressure operations aimed at improving transportation efficiency There is a strong demand.
大径、中〜厚肉のラインパイプは鋼板をＣ成形、Ｕ成形、Ｏ成形した後、成形された鋼板の端部同士を仮付溶接し、内外面から１層ずつシーム溶接後、拡管することによって製造される。 Large diameter, medium to thick line pipes are C-shaped, U-shaped, and O-shaped steel plates, and then the end portions of the formed steel plates are tack-welded to each other, and seam welded one by one from the inner and outer surfaces, and then expanded. Manufactured by.
ラインパイプのシーム溶接部のバースト特性、疲労特性など種々の特性には、溶接金属や溶接熱影響部の組織形態などの材質因子だけでなく、余盛高さなどの形状因子も大きく影響を及ぼすことが知られている。 Not only material factors such as weld metal and structure of the heat affected zone but also shape factors such as extra height greatly affect various characteristics such as the burst characteristics and fatigue characteristics of seam welds of line pipes. It is known.
例えば、特許文献１には、拡管前後のピーキング量を最適な範囲することと内面溶接の余盛高さを低減することにより鋼管の成形性およびバースト特性が向上することが記載されている。
For example,
特許文献２には、溶接金属と母材の引張強さの比を最適な範囲にするとともに、内外面シーム溶接部の余盛高さを低減することによりバースト特性が向上することが記載されている。
シーム溶接部の余盛高さが低くなると溶接止端部の形状がなだらかになるため、輸送する内容物の内圧変動などによる繰返し負荷に対する、溶接止端部での応力集中が軽減され、内圧疲労特性が向上する。 If the height of the seam weld is reduced, the shape of the weld toe becomes gentle, reducing stress concentration at the weld toe against repeated loads due to fluctuations in the internal pressure of the contents being transported, and internal pressure fatigue. Improved characteristics.
また、溶接鋼管を埋設して使用する場合は、管体の腐食を防止するために内外面にポリエチレンなど樹脂の被覆を行うが、シーム溶接部の余盛が高い場合、溶接部の上で膜厚が薄くなることがあり、その分をあらかじめ見込んで全体の膜厚を厚くして所定の膜厚を確保する必要があるため、樹脂の使用原単位が増加する。 In addition, when using a welded steel pipe embedded, the inner and outer surfaces are coated with a resin such as polyethylene to prevent corrosion of the pipe body. In some cases, the thickness may be reduced, and it is necessary to increase the overall film thickness by ensuring that amount in advance, so that a predetermined film thickness is secured.
上述したように、シーム溶接部の余盛高さを低く均一にすることで、溶接部の特性の向上や製造コストの低減が可能であるが、シーム溶接部の余盛高さを低く均一にするため、溶接入熱を下げるなどして溶着量を減らすことは、アンダーカットなどの溶接欠陥を助長させることになる。 As described above, by making the overfill height of the seam welded portion low and uniform, it is possible to improve the characteristics of the welded portion and reduce the manufacturing cost. However, the overfill height of the seam welded portion is made low and uniform. Therefore, reducing the welding amount by reducing the welding heat input or the like promotes welding defects such as undercut.
また、一般にシーム溶接時の開先断面積は、個々の鋼管の開先加工条件やプレス条件、連続仮付溶接の条件、その後の手直しにより異なるため、個々の鋼管に対して溶接条件を調整しなくては、シーム溶接部の余盛高さを低く均一に保つことができない。 In general, the groove cross-sectional area during seam welding varies depending on the groove processing conditions, press conditions, continuous tack welding conditions, and subsequent modifications of individual steel pipes. Without it, the height of the seam weld cannot be kept low and uniform.
すなわち、厚鋼板の幅端部に耳波が発生した場合、プレス時の局所的な開先潰れや連続仮付の溶接不良、補強溶接による余盛過多、内面溶接の抜けなどにより、同一の条件で開先を作製しても外面溶接直前における開先形状がばらつき、同一溶接条件で全長に渡って溶接すると、全長に渡って余盛高さが低く均一な溶接鋼管を得ることができない。 In other words, when an ear wave is generated at the width edge of a thick steel plate, the same conditions may occur due to local groove crushing during pressing, welding failure during continuous tacking, excessive reinforcement due to reinforcement welding, lack of internal welding, etc. Even if the groove is produced, the shape of the groove immediately before the outer surface welding varies, and when welding is performed over the entire length under the same welding conditions, it is not possible to obtain a uniform welded steel pipe having a low surplus height over the entire length.
一方、溶接条件の調整によらず、余盛り高さを低く均一にする方法として、グラインダなどによる研削があるが、この方法は生産性を著しく低下させる。また、溶接金属が高強度になるほど研削に費やす時間はますます増大する。 On the other hand, there is grinding by a grinder or the like as a method for making the surplus height low and uniform regardless of adjustment of welding conditions, but this method remarkably lowers productivity. Also, the higher the strength of the weld metal, the more time is spent on grinding.
なお、特許文献１および２には、余盛高さの範囲は規定しているものの、大量生産をした場合に余盛高さが低く均一な溶接鋼管を安定的に製造する方法については、開示されていない。
本発明は、溶接ままでシーム溶接部の余盛高さが低く均一でありなおかつ溶接欠陥の発生の少ない溶接鋼管を安定的に製造する方法を提供することを目的とする。 It is an object of the present invention to provide a method for stably producing a welded steel pipe that is welded and has a low overfill height at the seam welded portion and is uniform and has few weld defects.
本発明者らは、上記課題を達成するため、板厚が１５ｍｍ以上で、多電極サブマージアーク溶接法によりシーム溶接されるＵＯＥ鋼管を対象に、種々の検討を行い、以下の知見を得た。
１．余盛高さを安定させるために、同じ溶接条件で溶接したときの余盛高さと開先断面積の関係を調査した結果、余盛高さを低減するために溶接条件やフラックス散布高さ、フラックス粒度などを調節した場合においては、開先断面積の変動と余盛高さの変動がほぼ比例関係にある。２．従って、開先断面積に応じて溶着量の制御が可能な溶接パラメータの調整によって、余盛高さが低く均一な溶接鋼管が得られる。
３．開先断面積は上述したように同一鋼管内で大きくばらつくことがあるため、溶接中にオンラインで逐次開先断面積を検出しながら溶接条件を適宜変更することが、ビード全長で安定した余盛高さを得るために重要である。
４．開先断面積から予想される余盛高さが高い場合、溶着量を低減するために、各電極の溶接電流の総和と溶接速度の関係が特定の式を満たすように増加させ、開先断面積から予想される余盛高さが低いときは、当該特定の式を満たすように減少することによって、溶込み深さの変動を小さくしながら、余盛高さの制御が可能である。
５．各電極の電流の比が一定であれば、溶接電流、溶接速度を変動させても溶接ビード形状の梨型化による高温割れなどを防ぐことが可能である。
In order to achieve the above-mentioned problems, the present inventors have conducted various studies on a UOE steel pipe having a plate thickness of 15 mm or more and seam-welded by a multi-electrode submerged arc welding method, and obtained the following knowledge.
1. As a result of investigating the relationship between the surplus height and the groove cross-sectional area when welding under the same welding conditions in order to stabilize the surplus height, the welding conditions and flux distribution height to reduce the surplus height, When the flux particle size is adjusted, the change in groove cross-sectional area and the change in surplus height are approximately proportional. 2. Therefore, a uniform welded steel pipe with a low surplus height can be obtained by adjusting the welding parameters capable of controlling the welding amount in accordance with the groove cross-sectional area.
3. Since the groove cross-sectional area may vary greatly within the same steel pipe as described above, it is possible to change the welding conditions as appropriate while detecting the groove cross-sectional area online during welding. It is important to get height.
4). If the extra height expected from the groove cross-sectional area is high, in order to reduce the amount of welding, the relationship between the sum of the welding current of each electrode and the welding speed is increased so as to satisfy a specific formula, When the extra height expected from the area is low, the extra height can be controlled while reducing fluctuations in the penetration depth by reducing the height so as to satisfy the specific formula.
5). If the current ratio of each electrode is constant, it is possible to prevent hot cracking due to the pear shape of the weld bead shape even if the welding current and welding speed are varied.
本発明は、以上の知見をもとに更に検討を加えてなされたもので、すなわち、本発明は、
（１）両幅端に開先加工を行った板厚１５ｍｍ以上の鋼板を幅方向に筒状に冷間加工し、その突合せ部に仮付け溶接を行った後に、内外面１層ずつの多電極サブマージアーク溶接によってシーム溶接する溶接鋼管の製造方法において、
内面側溶接、外面側溶接の少なくとも一方のシーム溶接を行う前に、
開先断面積を全長に渡って連続測定して平均値を求め、当該平均値をもとに溶接ビードの余盛高さが０．１ｍｍ以上３．０ｍｍ以下になるように溶接することを特徴とする溶接鋼管の製造方法。
（２）両幅端に開先加工を行った板厚１５ｍｍ以上の鋼板を幅方向に筒状に冷間加工し、その突合せ部に仮付け溶接を行った後に、内外面１層ずつの多電極サブマージアーク溶接によってシーム溶接する溶接鋼管の製造方法において、
内面側溶接、外面側溶接の少なくとも一方のシーム溶接を行う際、溶接直前においてオンラインで開先断面積を求め、当該断面積をもとに溶接ビードの余盛高さが０．１ｍｍ以上３．０ｍｍ以下になるように溶接することを特徴とする溶接鋼管の製造方法。
（３）シーム溶接は、予め求めておいた溶接条件と開先断面積と余盛高さとの関係をもとに溶接条件を調整して行うことを特徴とする（１）または（２）記載の溶接鋼管の製造方法。
（４）溶接条件の調整は、溶接電流、溶接電圧、溶接速度およびワイヤ突出し長の１種または２種以上を調整することを特徴とする（１）ないし（３）のいずれか一つに記載の溶接鋼管の製造方法。
（５）溶接条件の調整は、溶接電流と溶接速度について行い、前記予め求めておいた開先断面積と溶接条件と余盛高さとの関係から、目標余盛高さを実現するために開先断面積に応じた適正溶接条件を求めて、これに従って溶接電流と溶接速度を設定することを特徴とする（４）記載の溶接鋼管の製造方法。
（６）溶接電流と溶接速度は、下式を満たすように調整することを特徴とする（５）記載の溶接鋼管の製造方法。
The present invention has been made based on the above findings and further studies, that is, the present invention
(1) A steel plate having a thickness of 15 mm or more that has been grooved at both width ends is cold-worked into a cylindrical shape in the width direction, and tack welding is performed on the butt portion. In the method of manufacturing a welded steel pipe to be seam welded by electrode submerged arc welding,
Before performing seam welding of at least one of inner surface side welding and outer surface side welding,
The groove cross-sectional area is continuously measured over the entire length to obtain an average value, and welding is performed so that the extra height of the weld bead is 0.1 mm or more and 3.0 mm or less based on the average value. A method for manufacturing a welded steel pipe.
(2) A steel plate having a thickness of 15 mm or more that has been grooved at both width ends is cold-worked into a cylindrical shape in the width direction, and tack welding is performed on the butt portion. In the method of manufacturing a welded steel pipe to be seam welded by electrode submerged arc welding,
2. When performing seam welding of at least one of inner surface side welding and outer surface side welding, a groove cross-sectional area is obtained online immediately before welding, and the extra height of the weld bead is 0.1 mm or more based on the cross-sectional area. The manufacturing method of the welded steel pipe characterized by welding so that it may become 0 mm or less.
(3) The seam welding is performed by adjusting the welding conditions based on the relationship between the welding conditions obtained in advance, the groove cross-sectional area, and the surplus height, (1) or (2) Manufacturing method of welded steel pipe.
(4) The welding condition is adjusted by adjusting one or more of a welding current, a welding voltage, a welding speed, and a wire protruding length, according to any one of (1) to (3), Manufacturing method of welded steel pipe.
(5) The welding conditions are adjusted with respect to the welding current and welding speed. From the relationship between the groove cross-sectional area, the welding conditions and the surplus height obtained in advance, the welding conditions are adjusted to achieve the target surplus height. The method for manufacturing a welded steel pipe according to (4), wherein an appropriate welding condition corresponding to the tip cross-sectional area is obtained, and a welding current and a welding speed are set according to the appropriate welding condition.
(6) The method for producing a welded steel pipe according to (5), wherein the welding current and the welding speed are adjusted to satisfy the following formula.
（ΣＩ）２／ｓ＝Ｃ
ただし、ΣＩ： 多電極サブマージアーク溶接の各電極の溶接電流の総和（Ａ）、ｓ： 溶接速度（ｍｍ／ｍｉｎ），Ｃ：定数
（７）各電極の溶接電流の比が一定になるように調整することを特徴とする（６）記載の溶接鋼管の製造方法。
（８）開先形状を検知する２次元レーザ距離計と、検知した情報をもとに開先断面積を計算して溶接条件の変更を行う１台以上の演算処理装置と、を備えた測定−演算系で開先断面積を求めることを特徴とする（１）乃至（８）のいずれか一つに記載の溶接鋼管の製造方法。
(ΣI) 2 / s = C
However, ΣI: Sum of welding current of each electrode of multi-electrode submerged arc welding (A), s: Welding speed (mm / min), C: Constant (7) The ratio of welding current of each electrode is constant. The method for manufacturing a welded steel pipe according to (6), wherein the adjustment is performed.
(8) Measurement including a two-dimensional laser distance meter that detects a groove shape and one or more arithmetic processing devices that calculate a groove cross-sectional area based on the detected information and change welding conditions. -The method for producing a welded steel pipe according to any one of (1) to (8), wherein a groove sectional area is obtained by an arithmetic system.
本発明によれば、シーム溶接部の余盛高さが低く均一で、溶接欠陥の発生の少ない溶接鋼管を安定的に製造することが可能となり、産業上極めて有効である。 According to the present invention, it is possible to stably manufacture a welded steel pipe having a low surfacing height at a seam welded portion and having few weld defects, which is extremely effective industrially.
本発明は、余盛高さの仕様が厳格な板厚： １５ｍｍ以上のＵＯＥ鋼管を対象とし、造管方法、開先断面積の測定方法、溶接条件の調整方法を規定する。なお、シーム溶接は多電極サブマージアーク溶接とする。 The present invention is directed to a UOE steel pipe having a strict thickness specification of 15 mm or more, and defines a pipe making method, a groove cross-sectional area measuring method, and a welding condition adjusting method. The seam welding is multi-electrode submerged arc welding.
本発明に係る溶接鋼管の製造方法では、内面側溶接、外面側溶接の少なくとも一方のシーム溶接を行う前に、開先断面積を測定して、所望する余盛高さの溶接部が得られるように溶接条件を調整する。 In the method for manufacturing a welded steel pipe according to the present invention, the weld cross-sectional area is measured before at least one seam welding of the inner surface side welding and the outer surface side welding is performed, and a weld portion having a desired extra height is obtained. Adjust the welding conditions as follows.
開先断面積は、１．溶接前に開先断面積を全長に渡って連続測定して平均値を求めたもの、２．溶接直前、すなわち、仮付け溶接により管状としたものに対してオンラインで求めたもののいずれであっても良く、これらいずれかの断面積をもとに溶接ビードの余盛高さが所望する値となるように溶接条件を調整する。前者の開先断面積の場合、余盛高さは０．１ｍｍ以上３．０ｍｍ以下、後者の開先断面積の場合は、より好ましい０．１ｍｍ以上２．５ｍｍ以下が達成される。余盛高さが低い場合の効果は２．５ｍｍ以下の場合、顕著に得られ、一方、余盛高さが低すぎるとアンダーカットやヒケスの影響により継手特性が劣化するため０．１ｍｍ以上が好ましい。 The groove cross-sectional area is 1. 1. An average value obtained by continuously measuring the groove cross-sectional area over the entire length before welding. Just before welding, that is, any of those obtained on-line with respect to a tube formed by tack welding, and the desired height of the weld bead height based on any of these cross-sectional areas Adjust the welding conditions so that In the case of the former groove cross-sectional area, the surplus height is 0.1 mm or more and 3.0 mm or less, and in the case of the latter groove cross-sectional area, a more preferable range of 0.1 mm or more and 2.5 mm or less is achieved. The effect when the surplus height is low is remarkably obtained when the surplus height is 2.5 mm or less. On the other hand, if the surplus height is too low, the joint characteristics deteriorate due to the influence of the undercut or Hikes. preferable.
溶接条件は、予め求めておいた溶接条件と開先断面積と余盛高さとの関係をもとに、測定した開先断面積に応じて上記の余盛り高さの範囲に収まるように選定する。予め求めておく溶接条件は、溶接電流、溶接電圧、溶接速度およびワイヤ突出し長の中から選ばれる１種または２種以上とする。 Welding conditions are selected based on the relationship between the welding conditions obtained in advance, the groove cross-sectional area, and the surplus height, and within the above-mentioned surplus height range according to the measured groove cross-sectional area. To do. The welding conditions determined in advance are one or more selected from welding current, welding voltage, welding speed, and wire protrusion length.
余盛高さや溶着量を支配する因子として他に、ワイヤ径、フラックス散布高さ、フラックス粒度なども影響するが大量生産時に鋼管ごとに条件を変更することが困難であるため、条件変更が比較的容易かつ溶着量を十分に変化させることができる上記４つの条件の中から選ばれる１種または２種以上を変更するものとした。 In addition to the factors that govern the surplus height and welding amount, the wire diameter, flux distribution height, and flux particle size also affect the conditions, but it is difficult to change the conditions for each steel pipe during mass production. One kind or two or more kinds selected from the above-mentioned four conditions that can easily change the welding amount easily.
溶接電流および溶接速度を調整する場合、本溶接に先立ち、事前に予備試験を行い、開先断面積と溶接条件と余盛高さとの関係を予め求めておく。標準的な溶接条件から大きく離れない範囲での溶接条件（溶接電流・溶接速度）の変更であれば、前記、開先断面積と溶接条件と余盛高さとの関係は、線形の近似式で近似することが可能である。この近似式を元に、或る目標余盛高さを実現する場合の、開先断面積とそれに応じた適正溶接条件との関係を求めることができる。該、開先断面積と溶接条件との関係を用いて、本溶接を実施することにより、適正な余盛高さを実現することができる。 When adjusting the welding current and the welding speed, a preliminary test is performed in advance prior to the main welding, and the relationship between the groove cross-sectional area, welding conditions, and surplus height is obtained in advance. If the welding conditions (welding current / welding speed) are changed within a range that does not deviate significantly from the standard welding conditions, the relationship between the groove cross-sectional area, welding conditions, and surplus height is a linear approximation. It is possible to approximate. Based on this approximate expression, the relationship between the groove cross-sectional area and the appropriate welding conditions corresponding to it can be obtained when a certain target height is realized. By performing the main welding using the relationship between the groove cross-sectional area and the welding condition, an appropriate extra height can be realized.
ここで、式（１）を満たしながら溶接電流および溶接速度を上げることにより、溶け込み深さをほぼ一定に保ちつつ、溶着量を減らして余盛高さを低減することができる。 Here, by increasing the welding current and the welding speed while satisfying the formula (1), it is possible to reduce the welding height by reducing the welding amount while keeping the penetration depth substantially constant.
（ΣＩ）２／ｓ＝Ｃ・・・・（１）
ただし、ΣＩ： 多電極サブマージアーク溶接の各電極の溶接電流の総和（Ａ）、ｓ： 溶接速度（ｍｍ／ｍｉｎ），Ｃ：定数
溶接電流を調整する場合、多電極サブマージアーク溶接の各電極の溶接電流の比が一定になるように調整することができる。このように各電極の溶接電流の比を一定に保つことで、適切な溶接断面形状を維持することができ、溶接断面形状の梨型化による高温割れなどの発生を防止することができる。
(ΣI) 2 / s = C (1)
However, ΣI: Sum of welding current of each electrode of multi-electrode submerged arc welding (A), s: Welding speed (mm / min), C: Constant When adjusting the welding current, each electrode of multi-electrode submerged arc welding The ratio of welding current can be adjusted to be constant. Thus, by keeping the ratio of the welding current of each electrode constant, it is possible to maintain an appropriate weld cross-sectional shape, and to prevent the occurrence of hot cracking due to the pear shape of the weld cross-sectional shape.
なお、開先断面積は、開先形状を検知する開先形状認識装置、例えば、２次元レーザ距離計と、検知した情報をもとに開先断面積を計算して溶接条件の変更を行う１台以上の演算処理装置と、を備えた測定−演算系で求めることが好ましい。 Note that the groove cross-sectional area is a groove shape recognition device that detects the groove shape, for example, a two-dimensional laser distance meter, and calculates the groove cross-sectional area based on the detected information and changes the welding conditions. It is preferable to obtain by a measurement-computation system including one or more arithmetic processing devices.
溶接直前においてオンラインで開先断面積を測定する場合、開先形状認識装置は溶接機よりも溶接方向前方に設置し、測定ピッチは、最低４００ｍｍピッチとすることが望ましい。開先断面積を考慮せずに溶接した鋼管のシーム溶接部高さの測定を行ったところ、おおよそ８００ｍｍの周期で最大値〜最小値〜最大値を繰り返す傾向にあったためである。なお、開先断面積の測定とともにシーム部のセンター合せも同時に行うことができる。 When measuring the groove cross-sectional area on-line immediately before welding, it is desirable that the groove shape recognition device is installed in front of the welding machine in the welding direction, and the measurement pitch is at least 400 mm. This is because when measuring the height of the seam welded portion of the steel pipe welded without considering the groove cross-sectional area, there was a tendency to repeat the maximum value to the minimum value to the maximum value at a cycle of approximately 800 mm. In addition, the centering of the seam portion can be performed simultaneously with the measurement of the groove cross-sectional area.
板厚２２ｍｍ、板幅２８インチ、板長１２０００ｍｍの厚鋼板の板長端にシーム溶接用のタブ板を溶接後、内面開先角度４５°、深さ６．５ｍｍ、外面開先角度４５°、深さ８，５ｍｍを狙ってエッジミラーで全長に渡り開先加工を行い、順にＣ成形、Ｕ成形、Ｏ成形し、厚鋼板の端部同士を２電極ＭＩＧ溶接で仮付溶接を行った。 After welding a tab plate for seam welding to the long end of a thick steel plate having a plate thickness of 22 mm, a plate width of 28 inches, and a plate length of 12000 mm, an inner face groove angle of 45 °, a depth of 6.5 mm, an outer face groove angle of 45 °, A groove was formed over the entire length with an edge mirror aiming at a depth of 8.5 mm, and C-shaped, U-shaped, and O-shaped were sequentially formed, and the ends of the thick steel plates were tack-welded by two-electrode MIG welding.
仮付溶接後、仮付ビード抜け部などに外面溶接側からＣＯ２溶接で補強溶接を行い、続いて内面溶接を４電極サブマージアーク溶接で行った。次に、外面溶接前に外面開先内の内面溶接抜け部や補強溶接部をグラインダで研削加工した後、４電極サブマージアーク溶接で外面溶接を行った。 After the tack welding, reinforcement welding was performed by CO 2 welding from the outer surface welding side to the temporary bead dropout portion, and then inner surface welding was performed by four-electrode submerged arc welding. Next, before the outer surface welding, the inner surface weld missing portion and the reinforcement welding portion in the outer surface groove were ground by a grinder, and then outer surface welding was performed by four-electrode submerged arc welding.
開先断面積の測定は、溶接機と同時に動くように溶接線前方に設置した２次元レーザ距離計で外面開先を全長に渡り倣い、溶接線上で溶接点の前方３０ｍｍにおける開先断面積を逐次算出することで行った。 The groove cross-sectional area is measured with a two-dimensional laser distance meter installed in front of the weld line so that it moves simultaneously with the welding machine. This was done by calculating sequentially.
外面溶接は、標準溶接条件から後述する手順で求めた開先断面積と溶接条件の関係にならい、前記逐次算出された開先断面積の測定結果に応じて溶接電流と溶接速度を変更しながら実施した。 External welding follows the relationship between the groove cross-sectional area obtained from the standard welding conditions in the procedure described later and the welding conditions, and changes the welding current and welding speed in accordance with the measurement results of the groove cross-sectional area calculated sequentially. Carried out.
比較例では、上記の断面積の測定結果に関わらず、全数を標準溶接条件で溶接を実施した。なお、標準溶接条件とは狙い通りの開先加工がなされたときの開先断面積のときに余盛り高さが狙いの中央値近傍（この場合は１．５ｍｍ）になるように決定した溶接条件を指す。 In the comparative example, regardless of the measurement result of the cross-sectional area, welding was performed on all of them under standard welding conditions. Note that the standard welding conditions are welding determined so that the surplus height is close to the target median value (in this case, 1.5 mm) when the groove cross-sectional area when the groove processing is performed as intended. Refers to a condition.
余盛高さは、高さ計を用いて管端５００ｍｍから１１５００ｍｍまで１０００ｍｍピッチで１１点測定し、最大値、最小値および平均値で評価した。 The extra height was measured at 11 points with a pitch of 1000 mm from 500 mm to 11500 mm at the pipe end using a height meter, and evaluated by the maximum value, minimum value, and average value.
溶接条件の調整にあたり、予備試験としてまず、開先断面積と溶接条件の関係を調査した。溶接条件は、表１に示す、標準溶接条件から第１電極の電流を２０Ａずつ変化させて、溶接電流と溶接速度が（ΣＩ）２／ｓ＝Ｃ（定数）かつ各電極の電流比が一定になるように、すなわち、（ΣＩ）２／ｓと各電極の電流比とが、それぞれ、標準溶接条件の場合の値と等しくなるように設定した。ここでは、測定した開先断面積が６０ｍｍ２付近と７０ｍｍ２付近にある対象材に対して溶接条件と余盛高さとの関係を調査した。 In adjusting the welding conditions, as a preliminary test, the relationship between the groove sectional area and the welding conditions was first investigated. The welding conditions are as shown in Table 1. The current of the first electrode is changed by 20 A from the standard welding conditions shown in Table 1, the welding current and the welding speed are (ΣI) 2 / s = C (constant), and the current ratio of each electrode is constant. In other words, (ΣI) 2 / s and the current ratio of each electrode were set to be equal to the values in the standard welding conditions. Here, the relationship between welding conditions and surplus height was investigated for target materials having a measured groove cross-sectional area near 60 mm 2 and 70 mm 2 .
図１に上記方法で溶接した場合の、開先断面積と余盛高さとの関係を示す。溶接電流が一定の場合、開先断面積が大きくなると平均余盛高さは小さくなる傾向にある。よって、図１中に示した５本の右下がりの直線のそれぞれが、５水準の第１電極溶接電流の場合に対応するというわけではないものの、これらの直線のように、余盛高さと開先断面積とは、溶接電流をパラメータとした線形関係にあるものと近似できる。すなわち、余盛高さと開先断面積と溶接電流との間に線形近似式を定めることができる。 FIG. 1 shows the relationship between the groove cross-sectional area and the surplus height when welding is performed by the above method. When the welding current is constant, the average overfill height tends to decrease as the groove cross-sectional area increases. Therefore, each of the five right-downward straight lines shown in FIG. 1 does not correspond to the case of the first electrode welding current at five levels, but as shown by these straight lines, The tip cross-sectional area can be approximated as having a linear relationship with the welding current as a parameter. That is, a linear approximation formula can be defined among the surplus height, the groove cross-sectional area, and the welding current.
こうして、余盛高さと開先断面積と溶接電流との間に線形近似式が求められると、今度は、所定の開先断面積に対して、特定の目標余盛高さを実現するための、溶接条件を求めることができる。すなわち、余盛高さと開先断面積とが決まると、前記線形近似式を用いることにより適正な溶接電流が求められ、さらに、前述の、溶接電流と溶接速度が（ΣＩ）２／ｓが一定という関係から、適正な溶接速度を求めることができるのである。目標余盛高さを１．５ｍｍとした場合の開先断面積と適正な溶接条件（第１電極溶接電流、溶接速度）との関係を図２に示す。 Thus, when a linear approximation expression is obtained among the surplus height, the groove cross-sectional area, and the welding current, this time, in order to realize a specific target surplus height for a predetermined groove cross-sectional area. The welding conditions can be determined. That is, when determined that the weld reinforcement height and groove cross-sectional area, the proper welding current is determined by using the linear approximation formula, further, the above-described, the welding current and welding speed (ΣI) 2 / s is constant Therefore, an appropriate welding speed can be obtained. FIG. 2 shows the relationship between the groove sectional area and the appropriate welding conditions (first electrode welding current, welding speed) when the target surplus height is 1.5 mm.
この関係をもとに、検出した開先断面積の変化とともに、余盛高さが平均１．５ｍｍになるように溶接電流および溶接速度を変化させながら外面溶接を行った。 Based on this relationship, outer surface welding was performed while changing the welding current and the welding speed so that the surplus height became 1.5 mm on average along with the detected change in the groove sectional area.
開先断面積を算出し溶接条件を変更しながら溶接した本発明例と、開先断面積の測定結果によらず標準溶接条件で溶接した比較例の平均開先断面積と余盛高さの関係を図３に示す。なお、最小値が０未満になっているものはアンダーカットが発生したものである。 Calculate the groove cross-sectional area and change the welding conditions.The example of the present invention and the comparative example welded under the standard welding conditions regardless of the measurement result of the groove cross-sectional area, The relationship is shown in FIG. Note that when the minimum value is less than 0, an undercut has occurred.
本発明例は、開先断面積の変動に対して適切に溶接条件を変更しているため余盛高さのばらつきが少なく、余盛高さの最大値、最小値ともに目標の範囲内に収まっている。 In the example of the present invention, since the welding conditions are appropriately changed with respect to the fluctuation of the groove cross-sectional area, there is little variation in the surplus height, and both the maximum and minimum surplus height are within the target range. ing.
一方、比較例は、開先断面積が小さいときは余盛が過剰であり、開先断面積が大きいときは余盛が小さくアンダーカットが発生していることが認められた。 On the other hand, in the comparative example, it was confirmed that when the groove cross-sectional area was small, the surplus was excessive, and when the groove cross-sectional area was large, the surplus was small and undercut occurred.
なお、仮付け溶接で管状とした後、溶接前に開先断面積を全長に渡って連続測定して求めた平均値を開先断面積として、上記試験を行った場合、本発明例と同様の結果が得られた。 When the above test is performed with the average value obtained by continuously measuring the groove cross-sectional area over the entire length before welding after making the tube by tack welding as in the case of the present invention, Results were obtained.
Claims (8)
内面側溶接、外面側溶接の少なくとも一方のシーム溶接を行う前に、
開先断面積を全長に渡って連続測定して平均値を求め、当該平均値をもとに溶接ビードの余盛高さが０．１ｍｍ以上３．０ｍｍ以下になるように溶接することを特徴とする溶接鋼管の製造方法。 A multi-electrode submerged arc with one inner / outer surface layer after cold-working a steel plate with a thickness of 15 mm or more with both ends at the width ends into a cylindrical shape in the width direction, and tacking the butt portion. In the method of manufacturing a welded steel pipe to be seam welded by welding,
Before performing seam welding of at least one of inner surface side welding and outer surface side welding,
The groove cross-sectional area is continuously measured over the entire length to obtain an average value, and welding is performed so that the extra height of the weld bead is 0.1 mm or more and 3.0 mm or less based on the average value. A method for manufacturing a welded steel pipe.
内面側溶接、外面側溶接の少なくとも一方のシーム溶接を行う際、溶接直前においてオンラインで開先断面積を求め、当該断面積をもとに溶接ビードの余盛高さが０．１ｍｍ以上３．０ｍｍ以下になるように溶接することを特徴とする溶接鋼管の製造方法。 A multi-electrode submerged arc with one inner / outer surface layer after cold-working a steel plate with a thickness of 15 mm or more with both ends at the width ends into a cylindrical shape in the width direction, and tacking the butt portion. In the method of manufacturing a welded steel pipe to be seam welded by welding,
2. When performing seam welding of at least one of inner surface side welding and outer surface side welding, the groove cross-sectional area is obtained online immediately before welding, and the extra height of the weld bead is 0.1 mm or more based on the cross-sectional area. The manufacturing method of the welded steel pipe characterized by welding so that it may become 0 mm or less.
（ΣＩ）２／ｓ＝Ｃ
ただし、ΣＩ： 多電極サブマージアーク溶接の各電極の溶接電流の総和（Ａ）、ｓ： 溶接速度（ｍｍ／ｍｉｎ），Ｃ：定数 6. The method for manufacturing a welded steel pipe according to claim 5, wherein the welding current and the welding speed are adjusted to satisfy the following formula.
(ΣI) 2 / s = C
Where ΣI: sum of welding currents of each electrode of multi-electrode submerged arc welding (A), s: welding speed (mm / min), C: constant
検知した情報をもとに開先断面積を計算して溶接条件の変更を行う１台以上の演算処理装置と、
を備えた測定−演算系により、開先断面積を算出し、さらに溶接条件の変更を行うことを特徴とする請求項１乃至７のいずれか一つに記載の溶接鋼管の製造方法。 A two-dimensional laser rangefinder for detecting the groove shape;
One or more arithmetic processing devices that calculate the groove cross-sectional area based on the detected information and change the welding conditions;
The method of manufacturing a welded steel pipe according to any one of claims 1 to 7, wherein a groove cross-sectional area is calculated by a measurement-computation system including: and further welding conditions are changed.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102380715A (en) * | 2010-12-22 | 2012-03-21 | 上海锅炉厂有限公司 | Method for assembling conical seat of gas cooler |
| JP2015100837A (en) * | 2013-11-27 | 2015-06-04 | Ｊｆｅスチール株式会社 | Beveling device and beveling method |
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| CN102380715A (en) * | 2010-12-22 | 2012-03-21 | 上海锅炉厂有限公司 | Method for assembling conical seat of gas cooler |
| JP2015100837A (en) * | 2013-11-27 | 2015-06-04 | Ｊｆｅスチール株式会社 | Beveling device and beveling method |
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