JP5915371B2 - UOE steel pipe manufacturing method - Google Patents

UOE steel pipe manufacturing method Download PDF

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JP5915371B2
JP5915371B2 JP2012115197A JP2012115197A JP5915371B2 JP 5915371 B2 JP5915371 B2 JP 5915371B2 JP 2012115197 A JP2012115197 A JP 2012115197A JP 2012115197 A JP2012115197 A JP 2012115197A JP 5915371 B2 JP5915371 B2 JP 5915371B2
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uoe steel
steel pipe
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靖 渡邉
靖 渡邉
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Nippon Steel Corp
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Nippon Steel and Sumitomo Metal Corp
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Description

本発明は、ＵＯＥ鋼管の製造方法に関し、特に、引っ張り強度が７０５ＭＰａ以下のＵＯＥ鋼管を製造する際に、シーム部の仮付け溶接で能率の向上と溶接欠陥の低減を図ったＵＯＥ鋼管の製造方法に関する。   The present invention relates to a UOE steel pipe manufacturing method, and in particular, when manufacturing a UOE steel pipe having a tensile strength of 705 MPa or less, a UOE steel pipe manufacturing method that improves efficiency and reduces welding defects by tack welding a seam portion. About.

天然ガスを長距離輸送するためのラインパイプは、外径が４００〜１６００ｍｍの大径溶接鋼管が使用され、この大径溶接鋼管としてはＵＯＥ鋼管が多用される。近年、天然ガス輸送用のラインパイプは、ガス輸送時に発生するエネルギー損失を抑制し、時間当たりに大量のガスを送給するために、送給ガス圧が高められ、さらに効率的なガス輸送の実現が求められる傾向にある。   A large-diameter welded steel pipe having an outer diameter of 400 to 1600 mm is used as a line pipe for transporting natural gas over a long distance, and a UOE steel pipe is frequently used as the large-diameter welded steel pipe. In recent years, line pipes for natural gas transportation have been improved in order to suppress energy loss that occurs during gas transportation and to supply a large amount of gas per hour. There is a tendency to be realized.

このため、ＵＯＥ鋼管の製造においては、高圧のガスに耐えることが可能な高い溶接品質の確保と、短期間に大量のラインパイプを供給できる高い生産性が要求されている。これに伴い、ＵＯＥ鋼管を製造する際、シーム部の本溶接で高速化を図るだけでなく、シーム部の仮付け溶接においても高速化と高品質化が強く求められるようになっている。   For this reason, in the manufacture of UOE steel pipes, high weld quality that can withstand high-pressure gas and high productivity that can supply a large amount of line pipe in a short time are required. As a result, when manufacturing UOE steel pipes, not only high speed is achieved by main welding of the seam part, but also high speed and high quality are strongly demanded in tack welding of the seam part.

ＵＯＥ鋼管の製造方法は、次のステップからなる：
（１）エッジプレーナにより、タブ板が取り付けられた厚板鋼板の両縁に開先加工を施す；
（２）Ｃプレス機により、鋼板の開先近辺の形状を製品管（ＵＯＥ鋼管）の規定外径に近い曲率に変形させるＣ成形を施し、Ｃ管を造形する；
（３）Ｕプレス機により、Ｃ管を断面Ｕ字形に変形させるＵ成形を施し、Ｕ管を造形する；
（４）Ｏプレス機により、Ｕ管を断面Ｏ字形に変形させるＯ成形を施し、オープンパイプのＯ管を造形する；
（５）Ｏ管のシーム部である開先同士の突き合わせを行いながら、ガスシールドアーク溶接法（ＧＭＡＷ）により、シーム部の仮付け溶接を行う；
（６）サブマージアーク溶接法（ＳＡＷ）により、仮付け溶接されたＯ管のシーム部に、内面側、外面側の順に本溶接を行う；
（７）拡管機により、シーム部が溶接された素管の外径を製品管で規定される寸法に精整し、ＵＯＥ鋼管を得る。
このようにして製造されたＵＯＥ鋼管は、タブ材を切除した後、超音波やＸ線により溶接部の検査を行い、その後に出荷される。 The UOE steel pipe manufacturing method consists of the following steps:
(1) The edge planer is used to perform groove processing on both edges of the thick steel plate to which the tab plate is attached;
(2) C forming is performed by deforming the shape of the vicinity of the groove of the steel sheet to a curvature close to the specified outer diameter of the product pipe (UOE steel pipe) by a C press machine;
(3) Using a U press machine, U molding is performed to deform the C tube into a U-shaped cross section, and the U tube is shaped;
(4) O-shaped to deform the U-tube into an O-shaped cross section by an O-press machine to form an open-pipe O-tube;
(5) Temporary welding of the seam portion is performed by a gas shield arc welding method (GMAW) while the grooves which are the seam portions of the O pipe are matched.
(6) Main welding is performed in order of the inner surface side and the outer surface side to the seam portion of the O-tube that has been tack welded by the submerged arc welding method (SAW);
(7) Using a pipe expander, the outer diameter of the raw pipe with the seam portion welded is adjusted to the size specified by the product pipe to obtain a UOE steel pipe.
The UOE steel pipe manufactured in this way is inspected for a welded portion by ultrasonic waves or X-rays after cutting the tab material, and then shipped.

仮付け溶接においては、ＣＯ2を主体としたガスをシールドガスとして溶接を行うＭＡＧ溶接や、Ａｒ等の不活性ガスを主体としたガスをシールドガスとして溶接を行うＭＩＧ溶接を採用することができるが、通常、前者のＭＡＧ溶接を採用することが多い。ＭＡＧ溶接の方が大電流であり、高い溶け込みと溶金の溶融が得られ、高い生産性を実現できるからである。 In tack welding, it is possible to employ MAG welding that performs welding using a gas mainly composed of CO 2 as a shielding gas, or MIG welding that performs welding using a gas mainly composed of an inert gas such as Ar as a shielding gas. However, usually the former MAG welding is often employed. This is because MAG welding has a larger current, and high penetration and melting of the molten metal can be obtained, so that high productivity can be realized.

ここで、仮付け溶接の目的は、ＳＡＷによる内面側の本溶接の際に、供給された溶金が外面側に漏れるいわゆる溶け落ちが発生するのを抑制し、これによって効率的な本溶接を達成することにある。仮にＯ成形で得られたＯ管を仮付け溶接することなく本溶接した場合、内面側の本溶接時に供給された溶金が開先突き合わせ部分から溶け落ち、本溶接における生産性が大きく阻害される。   Here, the purpose of tack welding is to suppress the occurrence of so-called burn-out, in which the supplied molten metal leaks to the outer surface side during the main welding on the inner surface side by SAW, thereby achieving efficient main welding. It is to achieve. If the O pipe obtained by O-molding is welded without tack welding, the molten metal supplied during the main welding on the inner surface side melts from the groove butting portion, and the productivity in the main welding is greatly hindered. The

また、仮付け溶接時に、スタッピングやハンピングの不用意な発生により溶接ビード形状が不良となり、これに伴って、ピンホールやブローホールといった溶接欠陥が発生した場合、この溶接欠陥は本溶接後においても残存し、その後の超音波やＸ線による検査で検出される。この場合、溶接欠陥部の補修や切り下げ等の処置が追加で必要となるため、生産性が大きく阻害される。   In addition, if the weld bead shape becomes poor due to inadvertent occurrence of stapling or humping during tack welding, and a welding defect such as a pinhole or blowhole occurs along with this, this welding defect will be Also remains and is detected by subsequent ultrasonic and X-ray examinations. In this case, since additional measures such as repairing or cutting down the weld defect portion are necessary, productivity is greatly hindered.

さらに、生産性を考慮しつつ設備投資を最小限に抑える観点から、例えば、本溶接の製造ラインが４本であるのに対して、仮付け溶接の製造ラインは１本または２本である場合が多く、仮付け溶接の溶接速度は本溶接の２〜４倍とされている。このため、高品質で高効率な仮付け溶接を行うことは、高い収益性と溶接部の信頼性を確保する上で極めて重要である。   Furthermore, from the viewpoint of minimizing capital investment while considering productivity, for example, when there are four production lines for main welding and one or two production lines for tack welding In many cases, the welding speed of tack welding is 2 to 4 times that of main welding. For this reason, it is extremely important to perform high-quality and high-efficiency tack welding in order to ensure high profitability and reliability of the welded portion.

仮付け溶接で能率の向上と溶接欠陥の低減を図る従来技術は、下記のものがある。特許文献１には、仮付け溶接の際、溶接スタート時から定常状態に移行するまでに溶接ビード形状が非連続となるスタッピングが発生したり、定常状態において溶接ビードが飛び飛びに形成されるハンピングが発生したりするのを抑制するため、溶接電流、電圧および溶接速度の適切な諸条件を設定することが開示されている。また、特許文献２には、ＭＩＧ溶接を採用する場合に、溶接ワイヤの太径化により溶接能率を改善させる方法が開示されている。特許文献３には、シーム部を予熱した状態で仮付け溶接を行うことにより、仮付け溶接の品質を向上させる方法が開示されている。   Conventional techniques for improving efficiency and reducing welding defects by tack welding include the following. In Patent Document 1, stap welding causes stapling in which the weld bead shape becomes discontinuous from the start of welding to transition to the steady state, or humping in which the weld bead is formed to jump in the steady state. In order to suppress the occurrence of the above, it is disclosed to set appropriate conditions of the welding current, voltage and welding speed. Patent Document 2 discloses a method for improving the welding efficiency by increasing the diameter of the welding wire when MIG welding is employed. Patent Document 3 discloses a method for improving the quality of tack welding by performing tack welding with the seam portion preheated.

特開昭５８−１３２３７４号公報JP 58-132374 A 特開昭５４−９９０５３号公報JP 54-99053 A 特開平７−１６７５０号公報Japanese Unexamined Patent Publication No. 7-16750

前記特許文献１〜３に開示される技術は、いずれも、主に溶接アークに着目して対策を講じたものであり、Ｕ成形後のＵ管の幅や、仮付け溶接時にＯ管を拘束するケージロールの押付け量に関しては何ら着目されていない。本発明者が試験検討を重ねたところ、引っ張り強度が７０５ＭＰａ以下（ＡＰＩ規格のＸ８０グレード以下）のＵＯＥ鋼管を製造する場合、そのようなＵ管幅や仮付け溶接時のケージロール押付け量が溶接品質に影響を及ぼすことが判明した。すなわち、仮にケージロールの押付けが弱いと、溶接中にＯ管が変則的に動くため、いかに溶接アークを安定させる溶接条件を設定しても高効率で高精度な仮付け溶接を行うことができない。一方、ケージロールの押付けが強すぎると、溶接部に過大な残留応力が集中するため、仮付け溶接後に溶接部で割れが発生し、その結果として、内面側の本溶接時に溶け落ちが発生することがある。   All of the techniques disclosed in Patent Documents 1 to 3 mainly take measures by paying attention to the welding arc, and restrain the width of the U pipe after U molding and the O pipe during tack welding. No attention is paid to the pressing amount of the cage roll. As a result of repeated examinations by the inventor, when manufacturing UOE steel pipes having a tensile strength of 705 MPa or less (API standard X80 grade or less), such U pipe width and cage roll pressing amount during tack welding are welded. It was found to affect the quality. In other words, if the cage roll is weakly pressed, the O-tube moves irregularly during welding. Therefore, even if the welding conditions for stabilizing the welding arc are set, highly efficient and highly accurate tack welding cannot be performed. . On the other hand, if the cage roll is pressed too much, excessive residual stress concentrates on the welded portion, so cracks occur in the welded portion after tack welding, and as a result, burnout occurs during the main welding on the inner surface side. Sometimes.

本発明は上記の問題に鑑みてなされたものであり、その目的は、引っ張り強度が７０５ＭＰａ以下のＵＯＥ鋼管を製造するに際し、次の特性を有するＵＯＥ鋼管の製造方法を提供することである：
仮付け溶接で能率の向上と溶接欠陥の低減を図ること。 The present invention has been made in view of the above problems, and its object is to provide a method for manufacturing a UOE steel pipe having the following characteristics when manufacturing a UOE steel pipe having a tensile strength of 705 MPa or less:
To improve efficiency and reduce welding defects by tack welding.

本発明の要旨は、次の通りである。   The gist of the present invention is as follows.

両縁に開先加工を施した鋼板にＣ成形およびＵ成形を順に行ってＵ管を造形し、このＵ管にＯ成形を行ってＯ管を造形し、このＯ管のシーム部にガスシールドアーク溶接法による仮付け溶接およびサブマージアーク溶接法による本溶接を順に行って、引っ張り強度が７０５ＭＰａ以下のＵＯＥ鋼管を製造する方法であって、
当該ＵＯＥ鋼管の製造方法は、
Ｕ成形の際、Ｕ管の幅（Ｗ）とＵＯＥ鋼管の外径（Ｄ）との比（Ｗ／Ｄ）が０．６０〜０．７５となる条件でＵ成形を行い、
仮付け溶接の際、シーム部を上側に位置させたＯ管に、ケージロールによって、左右からＯ管の外径の０．５〜１．０％の押付け量を付与するとともに、上方からＯ管の外径の０．１〜０．５％の押付け量を付与しながら、仮付け溶接を行うこと、
を特徴とするＵＯＥ鋼管の製造方法。 A U tube is formed by sequentially performing C forming and U forming on a steel plate having groove processing on both edges, and an O tube is formed by performing O forming on the U tube, and a gas shield is formed on the seam portion of the O tube. A method of manufacturing a UOE steel pipe having a tensile strength of 705 MPa or less by sequentially performing tack welding by arc welding and main welding by submerged arc welding,
The manufacturing method of the UOE steel pipe is as follows:
At the time of U forming, U forming is performed under the condition that the ratio (W / D) of the width (W) of the U pipe and the outer diameter (D) of the UOE steel pipe is 0.60 to 0.75,
At the time of tack welding, a pressing amount of 0.5 to 1.0% of the outer diameter of the O pipe is given from the left and right by the cage roll to the O pipe with the seam portion positioned on the upper side, and the O pipe from above. Performing tack welding while giving a pressing amount of 0.1 to 0.5% of the outer diameter of
A manufacturing method of a UOE steel pipe characterized by the above.

このＵＯＥ鋼管の製造方法では、前記仮付け溶接の際、溶接電流の印加を開始してから０．５〜２．０秒経過した後にＯ管の搬送を開始することが好ましい。   In this UOE steel pipe manufacturing method, it is preferable to start conveying the O pipe after 0.5 to 2.0 seconds have elapsed since the start of applying the welding current during the tack welding.

また、上記のＵＯＥ鋼管の製造方法では、前記仮付け溶接の際、Ｏ管の溶接開始管端部分における溶接速度（Ｖｅ）を、Ｏ管の中央部における溶接速度（Ｖｃ）の７０〜９０％とすることが好ましい。   In the UOE steel pipe manufacturing method, the welding speed (Ve) at the weld start pipe end portion of the O pipe is set to 70 to 90% of the welding speed (Vc) at the center of the O pipe during the tack welding. It is preferable that

本発明のＵＯＥ鋼管の製造方法は、下記の顕著な効果を有する：
引っ張り強度が７０５ＭＰａ以下のＵＯＥ鋼管を製造する際、仮付け溶接で能率を向上でき、溶接欠陥を低減できること。 The UOE steel pipe manufacturing method of the present invention has the following remarkable effects:
When manufacturing a UOE steel pipe having a tensile strength of 705 MPa or less, it is possible to improve efficiency by tack welding and reduce welding defects.

本発明のＵＯＥ鋼管の製造方法における仮付け溶接で用いられる溶接装置の構成を示す模式図であり、同図（ａ）は側面図を、同図（ｂ）は同図（ａ）のＡ−Ａ断面図をそれぞれ示す。It is a schematic diagram which shows the structure of the welding apparatus used by the tack welding in the manufacturing method of the UOE steel pipe of this invention, The figure (a) is a side view, The figure (b) is A- of the figure (a). A sectional views are shown respectively. ケージロールの押付け量の最適範囲を示す図である。It is a figure which shows the optimal range of the pressing amount of a cage roll. Ｕ管の幅（Ｗ）とＵＯＥ鋼管の外径（Ｄ）との比（Ｗ／Ｄ）の最適範囲を示す図である。It is a figure which shows the optimal range of ratio (W / D) of the width (W) of a U pipe, and the outer diameter (D) of a UOE steel pipe. 仮付け溶接開始後の溶接速度および溶接電流の推移の一例を示す図である。It is a figure which shows an example of transition of the welding speed and welding current after a tack welding start.

図１は、本発明のＵＯＥ鋼管の製造方法における仮付け溶接で用いられる溶接装置の構成を示す模式図であり、同図（ａ）は側面図を、同図（ｂ）は同図（ａ）のＡ−Ａ断面図をそれぞれ示す。   FIG. 1 is a schematic diagram showing a configuration of a welding apparatus used in tack welding in the method of manufacturing a UOE steel pipe according to the present invention, where FIG. 1 (a) is a side view, and FIG. A-A cross-sectional view of FIG.

図１に示すように、Ｃ成形、Ｕ成形およびＯ成形を順に経て得られたＯ管１は、シーム部１ａを上側に位置させた状態でチェーントランスファ２上に載置される。チェーントランスファ２は、チェーンドライブモータ３により、図１（ａ）中の実線矢印で示すように駆動される。チェーントランスファ２にはフック４が取り付けられており、チェーントランスファ２の駆動に伴ってＯ管１の後端がフック４で押され、これにより、Ｏ管１は、図１（ａ）中の白抜き矢印で示すように一方向に搬送される。   As shown in FIG. 1, the O tube 1 obtained through C molding, U molding, and O molding in this order is placed on the chain transfer 2 with the seam portion 1a positioned on the upper side. The chain transfer 2 is driven by a chain drive motor 3 as indicated by a solid arrow in FIG. A hook 4 is attached to the chain transfer 2, and the rear end of the O pipe 1 is pushed by the hook 4 as the chain transfer 2 is driven. As a result, the O pipe 1 is whitened in FIG. It is transported in one direction as indicated by the extraction arrow.

Ｏ管１の搬送路には、上流側（図１（ａ）では左側）から順に、フィンロール５、ケージロール群６、溶接機８および搬出ロール１２が配設されている。フィンロール５は鍔状に突出するフィン部を有しており、チェーントランスファ２によって搬送されるＯ管１は、その先端が先ずフィンロール５に誘導され、そのシーム部である開先同士の間にフィンロール５のフィン部が挿入される。ここで、実際には、Ｏ管１は、フィンロール５の前段に配設された図示しないジャッキによって左右に広げられ、適度に広がった開先同士の間にフィンロール５のフィン部が挿入される。これにより、Ｏ管１は、搬送中に不用意に周方向に回転することなく、シーム部１ａが上側に位置した姿勢に保持される。   A fin roll 5, a cage roll group 6, a welding machine 8, and a carry-out roll 12 are arranged in this order from the upstream side (left side in FIG. 1A) in the conveyance path of the O pipe 1. The fin roll 5 has a fin portion protruding in a bowl shape, and the O tube 1 conveyed by the chain transfer 2 is first guided at the tip by the fin roll 5 and between the grooves that are the seam portions. The fin portion of the fin roll 5 is inserted into Here, actually, the O pipe 1 is expanded to the left and right by a jack (not shown) disposed in the front stage of the fin roll 5, and the fin portion of the fin roll 5 is inserted between the moderately widened grooves. The As a result, the O-tube 1 is held in a posture in which the seam portion 1a is positioned on the upper side without inadvertently rotating in the circumferential direction during conveyance.

ケージロール群６は、図１（ｂ）に示すように、Ｏ管１の周囲を囲繞するように等角度間隔に配置された８つのケージロール６ａ〜６ｈを一群とし、これが複数段にわたって配設されてなる。これらのケージロール６ａ〜６ｈのうち、その位置を時計の文字盤に見立てて０時の位置に配置された上側ケージロール６ａは、シームロールとも称され、６時の位置に配置された下側ケージロール６ｅとの間にＯ管１を挟み込む。また、３時の位置に配置された右側ケージロール６ｃと９時の位置に配置された左側ケージロール６ｇは、Ｏ管１を左右から挟み込む。   As shown in FIG. 1 (b), the cage roll group 6 includes eight cage rolls 6a to 6h arranged at equiangular intervals so as to surround the periphery of the O pipe 1, and is arranged in a plurality of stages. Being done. Of these cage rolls 6a to 6h, the upper cage roll 6a arranged at the 0 o'clock position with the position of the clock face as a clock face is also referred to as a seam roll, and the lower cage roll 6a is arranged at the 6 o'clock position. The O pipe 1 is sandwiched between the cage roll 6e. The right cage roll 6c arranged at the 3 o'clock position and the left cage roll 6g arranged at the 9 o'clock position sandwich the O-tube 1 from the left and right.

チェーントランスファ２によって搬送されるＯ管１は、フィンロール５のフィン部の挿入によってシーム部１ａが上側に位置した状態で、上方から上側ケージロール６ａが押し付けられ、左右から右側ケージロール６ｃと左側ケージロール６ｇが押し付けられ、これらの押付けによって拘束されつつ、開先同士が突き合わされる。なお、上側ケージロール６ａ、右側ケージロール６ｃ、下側ケージロール６ｅおよび左側ケージロール６ｇ以外のケージロール６ｂ、６ｄ、６ｆ、６ｈは、多くの場合Ｏ管１に接触することはなく、補助的にＯ管１を拘束する。   The O-tube 1 conveyed by the chain transfer 2 is pressed with the upper cage roll 6a from above with the seam portion 1a positioned on the upper side by the insertion of the fin portion of the fin roll 5, and from the left and right to the right cage roll 6c. The cage roll 6g is pressed, and the grooves are brought into contact with each other while being restrained by the pressing. The cage rolls 6b, 6d, 6f, and 6h other than the upper cage roll 6a, the right cage roll 6c, the lower cage roll 6e, and the left cage roll 6g are not in contact with the O tube 1 in many cases and are auxiliary. The O tube 1 is restrained.

溶接機８は、トーチ９、溶接ワイヤ１０およびワイヤ送給電動機１１から構成される。トーチ９は、Ｏ管１のシーム部１ａに対向配置され、ワイヤ送給電動機１１の駆動により溶接ワイヤ１０が送り込まれる。チェーントランスファ２によって搬送されるＯ管１は、ケージロール群６によって開先同士が突き合わされた状態で、溶接機８によってシーム部１ａを仮付け溶接される。こうして、Ｏ管１は、チェーントランスファ２による搬送に追従して溶接機８を作動させることにより、先端から後端までの全域にわたってシーム部１ａを仮付け溶接される。   The welding machine 8 includes a torch 9, a welding wire 10, and a wire feeding / feeding motive 11. The torch 9 is disposed so as to face the seam portion 1 a of the O tube 1, and the welding wire 10 is fed by driving the wire feeding / feeding motive 11. The O pipe 1 conveyed by the chain transfer 2 is temporarily welded to the seam portion 1a by the welding machine 8 in a state where the grooves are abutted by the cage roll group 6. In this way, the O-tube 1 is temporarily welded to the seam portion 1a across the entire region from the front end to the rear end by operating the welding machine 8 following the conveyance by the chain transfer 2.

搬出ロール１２はＯ管１の姿勢を保持する。溶接終了間際には、Ｏ管１は、搬送の進行によってフィンロール５およびケージロール群６を完全に抜けて拘束を受けないため、周方向に回転し、シーム部１ａが上側に位置した状態からずれるおそれがあるからである。搬出ロール１２を設置すれば、Ｏ管１の仮付け溶接の精度を後端に至るまで維持することができる。   The carry-out roll 12 holds the posture of the O pipe 1. Just before the end of welding, the O-tube 1 completely rotates through the fin roll 5 and the cage roll group 6 and is not restrained by the progress of conveyance, so that the O-tube 1 rotates in the circumferential direction and the seam portion 1a is positioned on the upper side. This is because there is a risk of deviation. If the carry-out roll 12 is installed, the accuracy of the tack welding of the O pipe 1 can be maintained up to the rear end.

ここで、溶接機８のトーチ９には、デジタル溶接電源１３のＰ極が結線され、ケージロール群６のうちの下側ケージロール６ｅを支持するフレーム７には、デジタル溶接電源１３のＮ極が結線されている。デジタル溶接電源１３には制御盤１４が接続され、この制御盤１４はワイヤ送給電動機１１に接続されている。仮付け溶接時、制御盤１４は、デジタル溶接電源１３からトーチ９（溶接ワイヤ１０）とフレーム７（下側ケージロール６ｅ）との間に印加する溶接電流および電圧を制御するとともに、ワイヤ送給電動機１１による溶接ワイヤ１０の送り速度を制御する。また、制御盤１４は、チェーントランスファ２を駆動させるチェーンドライブモータ３に接続され、Ｏ管１の搬送速度、すなわち溶接速度を制御する。   Here, the P pole of the digital welding power source 13 is connected to the torch 9 of the welding machine 8, and the N pole of the digital welding power source 13 is connected to the frame 7 that supports the lower cage roll 6 e of the cage roll group 6. Is connected. A control panel 14 is connected to the digital welding power source 13, and the control panel 14 is connected to the wire feeding / powering motive 11. At the time of tack welding, the control panel 14 controls the welding current and voltage applied between the digital welding power source 13 between the torch 9 (welding wire 10) and the frame 7 (lower cage roll 6e) and also feeds the wire. The feeding speed of the welding wire 10 by the electric motor 11 is controlled. The control panel 14 is connected to a chain drive motor 3 that drives the chain transfer 2, and controls the conveying speed of the O pipe 1, that is, the welding speed.

本発明者は、上記目的を達成するため、引っ張り強度が７０５ＭＰａ以下のＵＯＥ鋼管を製造することを前提とし、種々の試験を実施して仮付け溶接で能率の向上と溶接欠陥の低減を図る鋭意検討を重ねた。その結果、以下の知見を得て、本発明を完成した。   In order to achieve the above object, the present inventor is diligently aiming to improve efficiency and reduce welding defects by tack welding by performing various tests on the premise that a UOE steel pipe having a tensile strength of 705 MPa or less is manufactured. Repeated examination. As a result, the following knowledge was obtained and the present invention was completed.

前記図１に示す溶接装置を用いて仮付け溶接を行う際、上述のとおり、Ｏ管１には、上方から上側ケージロール６ａを押し付け、左右から右側ケージロール６ｃと左側ケージロール６ｇを押し付ける。このとき、右側ケージロール６ｃと左側ケージロール６ｇの押付け量は、Ｏ管１の外径（ＯＤ）の０．５〜１．０％とする。これと同時に、上側ケージロール６ａの押付け量は、Ｏ管１の外径（ＯＤ）の０．１〜０．５％とする。これは以下の理由による。   When performing tack welding using the welding apparatus shown in FIG. 1, as described above, the upper cage roll 6a is pressed against the O tube 1 from above, and the right cage roll 6c and the left cage roll 6g are pressed from the left and right. At this time, the pressing amount of the right cage roll 6c and the left cage roll 6g is 0.5 to 1.0% of the outer diameter (OD) of the O pipe 1. At the same time, the pressing amount of the upper cage roll 6a is set to 0.1 to 0.5% of the outer diameter (OD) of the O tube 1. This is due to the following reason.

上側ケージロール（シームロール）６ａをＯ管１の外径（ＯＤ）の０．５％を超える強さでＯ管１に押し付けた場合、仮付け溶接中の溶接ビードには、Ｏ管１の曲率とは反対方向の曲げ力が働くため、仮付け溶接ビードが割れる問題が発生する。さらに、この場合、チェーントランスファ２には、チェーンドライブモータ３の回転を妨げる方向の力が働くため、Ｏ管１の搬送速度が不安定になりスタッピングやハンピング等の溶接欠陥が発生する。右側ケージロール６ｃと左側ケージロール６ｇをＯ管１の外径（ＯＤ）の１．０％を超える強さでＯ管１に押し付けた場合も同様である。   When the upper cage roll (seam roll) 6a is pressed against the O pipe 1 with a strength exceeding 0.5% of the outer diameter (OD) of the O pipe 1, the weld bead during tack welding has a Since a bending force in the direction opposite to the curvature acts, there arises a problem that the tack weld bead breaks. Further, in this case, a force in a direction that hinders the rotation of the chain drive motor 3 acts on the chain transfer 2, so that the conveying speed of the O-tube 1 becomes unstable, and welding defects such as stapping and humping occur. The same applies when the right cage roll 6c and the left cage roll 6g are pressed against the O tube 1 with a strength exceeding 1.0% of the outer diameter (OD) of the O tube 1.

一方、上側ケージロール６ａをＯ管１の外径（ＯＤ）の０．１％を下回る強さでＯ管１に押し付けた場合、Ｏ管１の拘束が緩く、Ｏ管１の搬送が不安定になる。右側ケージロール６ｃと左側ケージロール６ｇをＯ管１の外径（ＯＤ）の０．５％を下回る強さでＯ管１に押し付けた場合も同様である。   On the other hand, when the upper cage roll 6a is pressed against the O tube 1 with a strength that is less than 0.1% of the outer diameter (OD) of the O tube 1, the restraint of the O tube 1 is loose and the conveyance of the O tube 1 is unstable. become. The same applies to the case where the right cage roll 6c and the left cage roll 6g are pressed against the O tube 1 with a strength less than 0.5% of the outer diameter (OD) of the O tube 1.

図２に以上の関係をまとめる。図２は、ケージロールの押付け量の最適範囲を示す図である。右側ケージロール６ｃと左側ケージロール６ｇの押付け量をＯ管１の外径（ＯＤ）の０．５〜１．０％とするとともに、上側ケージロール６ａの押付け量をＯ管１の外径（ＯＤ）の０．１〜０．５％とした条件で仮付け溶接を行えば、溶接欠陥が極めて少ない良好な溶接品質を確保することができる。   FIG. 2 summarizes the above relationships. FIG. 2 is a diagram showing an optimum range of the pressing amount of the cage roll. The pressing amount of the right cage roll 6c and the left cage roll 6g is set to 0.5 to 1.0% of the outer diameter (OD) of the O tube 1 and the pressing amount of the upper cage roll 6a is set to the outer diameter of the O tube 1 ( If tack welding is performed under the condition of 0.1 to 0.5% of OD), it is possible to ensure good welding quality with very few welding defects.

仮付け溶接に先立ち、Ｕ成形の際、Ｕ管の幅（Ｗ）とＵＯＥ鋼管の外径（Ｄ）との比（Ｗ／Ｄ）が０．６０〜０．７５となる条件でＵ成形を行う。これは以下の理由による。なお、ここでいうＵ管の幅（Ｗ）は、当該Ｕ成形によって得られるＵ管の最大幅を意味し、ＵＯＥ鋼管の外径（Ｄ）は、当該Ｕ管を用いて製造されるＵＯＥ鋼管の公称外径を意味する。   Prior to tack welding, during U forming, U forming is performed under the condition that the ratio (W / D) of U tube width (W) to UOE steel tube outer diameter (D) is 0.60 to 0.75. Do. This is due to the following reason. In addition, the width | variety (W) of U pipe here means the maximum width of U pipe | tube obtained by the said U shaping | molding, and the outer diameter (D) of UOE steel pipe is UOE steel pipe manufactured using the said U pipe | tube. Means the nominal outside diameter.

Ｕ管幅（Ｗ）が過剰に狭く、Ｗ／Ｄが０．６未満であると、Ｏ成形後のＯ管に内在する残留応力に起因し、開先を非常に強い力で閉じようとする「閉」の力が働くため、前記図１に示す溶接装置を用いて仮付け溶接を行うに際し、Ｏ管の開先同士の間にフィンロールのフィン部を挿入するにあたり、ジャッキによって開先同士を適度に広げた状態にするのに多大な力が必要となる。このため、フィンロールの適用が不可能になる。   If the U tube width (W) is excessively narrow and W / D is less than 0.6, the groove tends to be closed with a very strong force due to the residual stress inherent in the O tube after O molding. Since the “closing” force works, when performing the tack welding using the welding apparatus shown in FIG. 1, when inserting the fin portion of the fin roll between the O-tube grooves, the gaps are made by a jack. A great deal of force is required to make the state of expansion moderately. For this reason, application of a fin roll becomes impossible.

一方、Ｕ管幅（Ｗ）が広すぎて、Ｗ／Ｄが０．７５を超える程度に大きくなると、Ｏ成形後、Ｏ管を開こうとする「開」の力が非常に強く働くため、前記図１に示す溶接装置を用いて仮付け溶接を行う際、右側ケージロールと左側ケージロールに多大な負荷がかかる。これに起因し、チェーントランスファがロック状態となり、Ｏ管の円滑な搬送ができなくなったり、仮付け溶接後の溶接ビードに割れが発生したりする。   On the other hand, if the U tube width (W) is too wide and the W / D is increased to a level exceeding 0.75, the “open” force to open the O tube works very strongly after the O molding, When tack welding is performed using the welding apparatus shown in FIG. 1, a great load is applied to the right cage roll and the left cage roll. As a result, the chain transfer is locked, and the O-tube cannot be smoothly transported, or the weld bead after the tack welding is cracked.

図３に以上の関係をまとめる。図３は、Ｕ管の幅（Ｗ）とＵＯＥ鋼管の外径（Ｄ）との比（Ｗ／Ｄ）の最適範囲を示す図である。Ｗ／Ｄが０．６０〜０．７５となるＵ管を用いてＯ成形を行い、得られたＯ管に仮付け溶接を行うことにより、支障なくフィンロールを適用することが可能となり、しかも、溶接欠陥が極めて少ない良好な溶接品質を確保することができる。   FIG. 3 summarizes the above relationships. FIG. 3 is a diagram showing an optimum range of the ratio (W / D) of the width (W) of the U pipe and the outer diameter (D) of the UOE steel pipe. By performing O-molding using a U pipe with a W / D of 0.60 to 0.75 and performing tack welding on the obtained O pipe, it becomes possible to apply a fin roll without any trouble. It is possible to ensure good welding quality with very few welding defects.

また、前記図１に示す溶接装置を用いた仮付け溶接においては、制御盤からの指令により、チェーンドライブモータを駆動させてＯ管を搬送し、Ｏ管の先端のタブ材が溶接機のトーチ直下に到達した段階でＯ管の搬送を一旦停止させる。そして、デジタル溶接電源による溶接電流の印加を開始してから、すなわち仮付け溶接を現実に開始してから０．５〜２．０秒経過した後に、Ｏ管の搬送を再び開始することが好ましい。その理由は次のとおりである。   Further, in the tack welding using the welding apparatus shown in FIG. 1, the chain drive motor is driven by the command from the control panel to convey the O tube, and the tab material at the tip of the O tube is used as a torch of the welding machine. When reaching the position directly below, the conveyance of the O pipe is temporarily stopped. And it is preferable to start conveyance of the O pipe again after 0.5 to 2.0 seconds have elapsed after starting the application of the welding current by the digital welding power source, that is, after actually starting the tack welding. . The reason is as follows.

図４は、仮付け溶接開始後の溶接速度および溶接電流の推移の一例を示す図である。同図に示す溶接速度は、設定した速度を１とした比率で示している。同図に示す溶接電流も同様に、設定した電流値を１とした比率で示している。なお、同図は、外径が３６インチ、肉厚が２５．４ｍｍで、Ｘ６５グレードのＵＯＥ鋼管を製造する際、直径が４．０ｍｍの溶接ワイヤを用い、溶接速度の設定を５．０ｍ／ｍｉｎ、溶接電流の設定を１２００Ａとした条件で仮付け溶接を行った場合の結果である。   FIG. 4 is a diagram showing an example of the transition of welding speed and welding current after the start of tack welding. The welding speed shown in the figure is shown as a ratio where the set speed is 1. Similarly, the welding current shown in the figure is also shown in a ratio where the set current value is 1. In this figure, when manufacturing an X65 grade UOE steel pipe having an outer diameter of 36 inches and a wall thickness of 25.4 mm, a welding wire with a diameter of 4.0 mm is used, and the welding speed is set to 5.0 m / It is a result at the time of performing tack welding on the conditions which set the setting of min and welding current to 1200A.

図４に示すように、制御盤からの指令により、溶接機への溶接電流の印加開始に伴って仮付け溶接を開始したとき、溶接電流は瞬時に設定電流値に達して安定するわけではなく、約０．５秒経過した後に安定する。このため、溶接電流の印加と同時にＯ管の搬送を開始するのではなく、０．５〜２．０秒程度のアイドルタイムを設けてＯ管の搬送を開始すれば、溶接電流が設定電流値に安定し溶接状態も安定する。例えば、図４に示すように、溶接電流の印加を開始してから０．８秒経過した後にＯ管の搬送を開始すればよい。   As shown in FIG. 4, when tack welding is started with the start of application of a welding current to the welding machine according to a command from the control panel, the welding current does not instantaneously reach the set current value and stabilize. Stabilizes after about 0.5 seconds. For this reason, if the welding of the O pipe is not started at the same time as the welding current is applied, but the idle time of about 0.5 to 2.0 seconds is provided to start the transportation of the O pipe, the welding current is set to the set current value. The welding state is also stable. For example, as shown in FIG. 4, the conveyance of the O tube may be started after 0.8 seconds have elapsed from the start of applying the welding current.

さらに、前記図１に示す溶接装置を用いた仮付け溶接においては、制御盤からの指令により、Ｏ管の溶接開始管端部分における溶接速度（Ｖｅ）を、Ｏ管の中央部における溶接速度（Ｖｃ）の７０〜９０％とすることが好ましい。仮付け溶接を高速で行う場合、溶接開始時に、いきなりＯ管中央部で適用する高速の溶接速度（Ｖｃ）にすると、溶接ビードの性状が悪化し易いからである。なお、Ｏ管の溶接開始管端部分とは、Ｏ管の全長の１％の領域のことである。   Further, in the tack welding using the welding apparatus shown in FIG. 1, the welding speed (Ve) at the welding start pipe end portion of the O pipe is changed to the welding speed at the central part of the O pipe (in accordance with a command from the control panel). Vc) is preferably 70 to 90%. This is because, when tack welding is performed at a high speed, if the welding speed (Vc) is suddenly applied at the center of the O pipe at the start of welding, the properties of the weld bead are likely to deteriorate. In addition, the welding start pipe edge part of O pipe is a 1% area | region of the full length of O pipe.

加えて、前記図１に示す溶接装置を用いた仮付け溶接においては、溶接機に電流を印加するための溶接電源としてデジタル溶接電源を適用しているので、従来のアナログ式の溶接電源と比較し、溶接電流の波形の位相制御や周波数制御を行える。このため、溶接ビード形状や溶け込みを精緻に調節することができ、溶接速度の高速化も実現できる。例えば、溶接電流の周波数を８０ｋＨｚとすれば、溶滴のスプレー移行を高速・高頻度とし、溶接時に発生するスパッタを抑制することもできる。   In addition, in the tack welding using the welding apparatus shown in FIG. 1, since a digital welding power source is applied as a welding power source for applying a current to the welding machine, it is compared with a conventional analog welding power source. In addition, phase control and frequency control of the welding current waveform can be performed. For this reason, the weld bead shape and penetration can be precisely adjusted, and the welding speed can be increased. For example, if the frequency of the welding current is 80 kHz, the spray transfer of the droplets can be performed at high speed and high frequency, and spatters generated during welding can be suppressed.

本発明のＵＯＥ鋼管の製造方法は、Ｕ成形の際、Ｕ管の幅（Ｗ）とＵＯＥ鋼管の外径（Ｄ）との比（Ｗ／Ｄ）が０．６０〜０．７５となる条件でＵ成形を行い、仮付け溶接の際、シーム部を上側に位置させたＯ管に、ケージロールによって、左右からＯ管の外径の０．５〜１．０％の押付け量を付与するとともに、上方からＯ管の外径の０．１〜０．５％の押付け量を付与しながら、仮付け溶接を行うこととする。これにより、特に５ｍ／ｍｉｎ以上の高速で仮付け溶接を行う場合であっても、ピンホールやブローホール等の溶接欠陥や溶接部の割れを低減させることができる。その結果、内面側の本溶接時に溶け落ちの発生を防止することができ、本溶接後に仮付け溶接欠陥の残存に伴う溶接補修による生産能率の低下や、欠陥部切り下げによる歩留ロスを抑制することができる。したがって、本発明は、高効率的で高品質な溶接を行うことが可能となる。   The manufacturing method of the UOE steel pipe of the present invention is such that the ratio (W / D) between the width (W) of the U pipe and the outer diameter (D) of the UOE steel pipe is 0.60 to 0.75 during U forming. U-molding is performed, and at the time of tack welding, a pressing amount of 0.5 to 1.0% of the outer diameter of the O tube is applied from the left and right to the O tube with the seam portion positioned on the upper side. At the same time, tentative welding is performed while applying a pressing amount of 0.1 to 0.5% of the outer diameter of the O tube from above. Thereby, even when tack welding is performed particularly at a high speed of 5 m / min or more, welding defects such as pinholes and blowholes and cracks in the welded portion can be reduced. As a result, it is possible to prevent the occurrence of burn-out during the main welding on the inner surface side, and suppress the decrease in production efficiency due to welding repair accompanying the remaining of the temporary welding defects after the main welding and the yield loss due to the devaluation of the defective portion. be able to. Therefore, the present invention enables highly efficient and high quality welding.

本発明は、天然ガス輸送用のラインパイプに適用されるＵＯＥ鋼管、とりわけＡＰＩ規格のＸ８０グレード以下のＵＯＥ鋼管の製造に有効に利用できる。   INDUSTRIAL APPLICABILITY The present invention can be effectively used for the manufacture of UOE steel pipes applied to natural gas transportation line pipes, particularly UOE steel pipes having API standard X80 grade or less.

１：Ｏ管、 １ａ：シーム部、 ２：チェーントランスファ、
３：チェーンドライブモータ、 ４：フック、 ５：フィンロール、
６：ケージロール群、 ６ａ〜６ｈ：ケージロール、
７：下側ケージロールのフレーム、 ８：溶接機、 ９：トーチ、
１０：溶接ワイヤ、 １１：ワイヤ送給電動機、 １２：搬出ロール、
１３：デジタル溶接電源、 １４：制御盤 1: O pipe, 1a: Seam part, 2: Chain transfer,
3: chain drive motor, 4: hook, 5: fin roll,
6: cage roll group, 6a to 6h: cage roll,
7: Frame of the lower cage roll, 8: Welding machine, 9: Torch,
10: welding wire, 11: wire feeding and feeding motive, 12: unloading roll,
13: Digital welding power source, 14: Control panel

Claims (3)

両縁に開先加工を施した鋼板にＣ成形およびＵ成形を順に行ってＵ管を造形し、このＵ管にＯ成形を行ってＯ管を造形し、このＯ管のシーム部にガスシールドアーク溶接法による仮付け溶接およびサブマージアーク溶接法による本溶接を順に行って、引っ張り強度が７０５ＭＰａ以下のＵＯＥ鋼管を製造する方法であって、
当該ＵＯＥ鋼管の製造方法は、
Ｕ成形の際、Ｕ管の幅（Ｗ）とＵＯＥ鋼管の外径（Ｄ）との比（Ｗ／Ｄ）が０．６０〜０．７５となる条件でＵ成形を行い、
仮付け溶接の際、シーム部を上側に位置させたＯ管に、ケージロールによって、左右からＯ管の外径の０．５〜１．０％の押付け量を付与するとともに、上方からＯ管の外径の０．１〜０．５％の押付け量を付与しながら、仮付け溶接を行うこと、
を特徴とするＵＯＥ鋼管の製造方法。 A U tube is formed by sequentially performing C forming and U forming on a steel plate having groove processing on both edges, and an O tube is formed by performing O forming on the U tube, and a gas shield is formed on the seam portion of the O tube. A method of manufacturing a UOE steel pipe having a tensile strength of 705 MPa or less by sequentially performing tack welding by arc welding and main welding by submerged arc welding,
The manufacturing method of the UOE steel pipe is as follows:
At the time of U forming, U forming is performed under the condition that the ratio (W / D) of the width (W) of the U pipe and the outer diameter (D) of the UOE steel pipe is 0.60 to 0.75,
At the time of tack welding, a pressing amount of 0.5 to 1.0% of the outer diameter of the O pipe is given from the left and right by the cage roll to the O pipe with the seam portion positioned on the upper side, and the O pipe from above. Performing tack welding while giving a pressing amount of 0.1 to 0.5% of the outer diameter of
A manufacturing method of a UOE steel pipe characterized by the above. 前記仮付け溶接の際、溶接電流の印加を開始してから０．５〜２．０秒経過した後にＯ管の搬送を開始すること、
を特徴とする請求項１に記載のＵＯＥ鋼管の製造方法。 In the tack welding, starting the transfer of the O pipe after 0.5 to 2.0 seconds have elapsed from the start of applying the welding current;
The manufacturing method of the UOE steel pipe according to claim 1 characterized by these. 前記仮付け溶接の際、Ｏ管の溶接開始管端部分における溶接速度（Ｖｅ）を、Ｏ管の中央部における溶接速度（Ｖｃ）の７０〜９０％とすること、
を特徴とする請求項１または２に記載のＵＯＥ鋼管の製造方法。 During the tack welding, the welding speed (Ve) at the welding start pipe end portion of the O pipe is set to 70 to 90% of the welding speed (Vc) at the center of the O pipe,
The manufacturing method of the UOE steel pipe according to claim 1 or 2 characterized by these.
JP2012115197A 2012-05-21 2012-05-21 UOE steel pipe manufacturing method Expired - Fee Related JP5915371B2 (en)

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