JP6780489B2 - Manufacturing method of electric pipe and electric pipe - Google Patents

Manufacturing method of electric pipe and electric pipe Download PDF

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JP6780489B2
JP6780489B2 JP2016246397A JP2016246397A JP6780489B2 JP 6780489 B2 JP6780489 B2 JP 6780489B2 JP 2016246397 A JP2016246397 A JP 2016246397A JP 2016246397 A JP2016246397 A JP 2016246397A JP 6780489 B2 JP6780489 B2 JP 6780489B2
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outer diameter
steel pipe
diameter
wall thickness
average value
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JP2018099703A (en
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慧悟 加藤
慧悟 加藤
和田 学
学 和田
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Nippon Steel Corp
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Description

本発明は、電縫鋼管及び電縫鋼管の製造方法に関するものである。 The present invention relates to an electric resistance welded steel pipe and a method for manufacturing an electric resistance welded steel pipe.

特許文献1に記載されているように、中空に形成された管の端部の径を調整する方法が知られている。管の端部の径を調整することにより複数の管を直線的に組立可能とすれば、長い筒を形成することが可能となる。このようにして形成された長い筒は、鉄塔の柱として用いられる場合がある。 As described in Patent Document 1, a method of adjusting the diameter of the end portion of a hollow-formed tube is known. If a plurality of pipes can be assembled linearly by adjusting the diameter of the end portion of the pipes, a long cylinder can be formed. The long cylinder formed in this way may be used as a pillar of a steel tower.

特開昭51−149158号公報JP-A-51-149158

ところで、組立可能な管を形成する場合、図5に示すように、電縫鋼管の一部を縮径することがある。しかしながら、縮径加工がなされた管には座屈が発生する場合があった。この管の厚みと外径の分布を分析した結果、図6に示すような結果を得た。この電縫鋼管は直径が165.2mm、厚みが3.2mmであるSTK540の電縫鋼管である。なお、図6の上端が溶接部であり、そこから円周方向に22.5度ずつずれた箇所における測定結果を示しているため、合計16カ所についての測定結果を示している。測定結果と座屈箇所を対比させた結果、厚みが薄い箇所と外径が小さい箇所が重なると、縮径時に、その部分から座屈が生じることが判明した。 By the way, when forming an assembling pipe, a part of the electric resistance welded steel pipe may be reduced in diameter as shown in FIG. However, buckling may occur in the tube that has been reduced in diameter. As a result of analyzing the distribution of the thickness and the outer diameter of this tube, the results shown in FIG. 6 were obtained. This electric resistance pipe is an STK540 steel pipe with a diameter of 165.2 mm and a thickness of 3.2 mm. Since the upper end of FIG. 6 is the welded portion and the measurement results are shown at locations deviated by 22.5 degrees in the circumferential direction, the measurement results for a total of 16 locations are shown. As a result of comparing the measurement results with the buckling points, it was found that when the thin part and the small outer diameter part overlap, buckling occurs from that part at the time of diameter reduction.

本発明はこのような過程でなされたものであり、本発明の課題は、縮径加工による座屈を抑制した電縫鋼管とすることである。 The present invention has been made in such a process, and an object of the present invention is to obtain an electrosewn steel pipe in which buckling due to diameter reduction processing is suppressed.

上記課題を解決するためになされた本発明は次の手段を採用する。先ず、第一の手段は、周方向平均値より5%以上減肉している位置と、周方向平均値より外径が0.2%以上凹んでいる位置が重複していないことを特徴とする縮径加工強度に優れた電縫鋼管である。 The present invention made to solve the above problems employs the following means. First, the first means is that the position where the wall thickness is reduced by 5% or more from the circumferential average value and the position where the outer diameter is recessed by 0.2% or more from the circumferential average value do not overlap. It is an electrosewn steel pipe with excellent diameter processing strength.

第二の手段は、肉厚が最小となる周方向の位置と外径が最小となる位置が±10°以上離れていることを特徴とする縮径加工強度に優れた電縫鋼管である。 The second means is an electro-sewn steel pipe having excellent diameter reduction processing strength, characterized in that the position in the circumferential direction where the wall thickness is the minimum and the position where the outer diameter is the minimum are separated by ± 10 ° or more.

第三の手段は、周方向平均値より5%以上減肉している位置と、周方向平均値より外径が0.2%以上凹んでいる位置が重複しておらず、かつ周方向の肉厚が最小となる位置と外径が最小となる位置が±10°以上離れていることを特徴とする縮径加工強度に優れた電縫鋼管である。 In the third means, the position where the wall thickness is reduced by 5% or more from the circumferential average value and the position where the outer diameter is recessed by 0.2% or more from the circumferential average value do not overlap, and the wall thickness in the circumferential direction is not overlapped. This is an electric resistance welded steel pipe having excellent diameter reduction processing strength, characterized in that the position where the minimum diameter is minimized and the position where the outer diameter is minimized are separated by ± 10 ° or more.

第四の手段は、エッジベンドロールの段数が2段以下であり、サイジングロールでの塑性加工量が1.2%以上であることを特徴とする縮径加工強度に優れた電縫鋼管の製造方法である。 The fourth means is a method for manufacturing an electrosewn steel pipe having excellent diameter reduction machining strength, characterized in that the number of steps of the edge bend roll is 2 or less and the amount of plastic working on the sizing roll is 1.2% or more. is there.

本発明では、縮径加工による座屈を抑制した電縫鋼管とすることができる。 In the present invention, it is possible to obtain an electrosewn steel pipe in which buckling due to diameter reduction processing is suppressed.

電縫鋼管の偏肉割合と外径偏差と座屈の発生の有無との関係を示した図である。It is a figure which showed the relationship between the uneven thickness ratio of the electric resistance pipe, the outer diameter deviation, and the presence or absence of buckling. 電縫鋼管の製造に使用される各ロールの使用目的を表した図である。It is a figure which showed the purpose of use of each roll used for manufacturing the electric resistance steel pipe. 実施形態に該当する製造方法による電縫鋼管の厚みと外径に関する周方向の分布例を表す図である。It is a figure which shows the distribution example in the circumferential direction about the thickness and the outer diameter of the electric resistance welded steel pipe by the manufacturing method corresponding to embodiment. 他の製造方法による電縫鋼管の厚みと外径に関する周方向の分布の他の例を表す図である。It is a figure which shows another example of the distribution in the circumferential direction about the thickness and the outer diameter of the electric resistance welded steel pipe by another manufacturing method. 従来技術の電縫鋼管の端部を縮径した例を示す図である。It is a figure which shows the example which reduced the diameter of the end portion of the electric resistance steel pipe of the prior art. 従来技術の電縫鋼管の厚みと外径に関する周方向の分布を表す図である。It is a figure which shows the distribution in the circumferential direction about the thickness and the outer diameter of the electric resistance steel pipe of the prior art.

以下では、発明の実施形態について説明するが、まず、縮径により座屈した電縫鋼管についての分析内容について説明する。本発明者らによる分析により、厚みが薄い箇所と外径が小さい箇所が重なると、縮径時に、その部分から座屈が生じることが判明した。そこで、更なる分析を行うため、肉厚や外形の分布と座屈発生の有無の関係や、偏肉割合と外径偏差と座屈発生の有無の関係を調査した。偏肉割合は、最大となる肉厚から最小となる肉厚を引いた値が標準的な肉厚の何パーセントに当たるのかを示したものであり、マイナスを付して表す。また、外径偏差は、最大となる外径から最小となる外径を引いた値が標準的な外径(直径)の何パーセントに当たるのかを示したものであり、マイナスを付して表す。 Hereinafter, embodiments of the present invention will be described, but first, the content of analysis of an electric resistance welded steel pipe buckled due to diameter reduction will be described. Analysis by the present inventors has revealed that when a portion having a small thickness and a portion having a small outer diameter overlap, buckling occurs from that portion when the diameter is reduced. Therefore, in order to carry out further analysis, we investigated the relationship between the distribution of wall thickness and outer shape and the presence or absence of buckling, and the relationship between the uneven thickness ratio and the outer diameter deviation and the presence or absence of buckling. The unbalanced wall ratio indicates what percentage of the standard wall thickness is the value obtained by subtracting the minimum wall thickness from the maximum wall thickness, and is indicated by adding a minus. The outer diameter deviation indicates what percentage of the standard outer diameter (diameter) the value obtained by subtracting the minimum outer diameter from the maximum outer diameter corresponds to, and is indicated by adding a minus.

この調査の結果、周方向平均値より5%以上減肉している位置と、周方向平均値より外径が0.2%以上凹んでいる位置が重複している場合、縮径加工時に座屈が発生することがわかった。つまり、そのような重複がなされないことが好ましいことが判明した。 As a result of this investigation, if the position where the wall thickness is reduced by 5% or more from the circumferential average value and the position where the outer diameter is recessed by 0.2% or more from the circumferential average value overlap, buckling occurs during diameter reduction processing. It turned out to occur. That is, it turned out that it is preferable that such duplication is not made.

また、電縫鋼管は、その肉厚が最小となる周方向の位置と外径が最小となる位置が±10°以上離れている場合には、縮径加工強度に優れた電縫鋼管となることが判明した。 In addition, when the position in the circumferential direction where the wall thickness is the minimum and the position where the outer diameter is the minimum are separated by ± 10 ° or more, the electrosewn steel pipe becomes an electrosewn steel pipe having excellent diameter reduction processing strength. It has been found.

また、図1に示すように、その肉厚が最小となる周方向の位置と外径が最小となる位置が±10°の角度範囲に属する位置にある場合には、外径偏差が-0.2%以下、かつ、偏肉割合が-5%以下である場合には、座屈が発生したが、それ以外場合においては座屈が見られなかった。なお、図6に示した例では、厚みが3.2mmであることを標準とした電縫鋼管である。また、基準肉厚(3.2mm)から最小となる肉厚を引いた値は0.23mmである。したがって、偏肉割合は-7.19%である。また、直径が165.2mmである電縫鋼管であり、基準外径(φ165.2mm)から最小となる外径を引いた値は0.45mmである。したがって、外径偏差は-0.27%である。 Further, as shown in FIG. 1, when the position in the circumferential direction where the wall thickness is the minimum and the position where the outer diameter is the minimum belong to the angle range of ± 10 °, the outer diameter deviation is -0.2. Buckling occurred when% or less and the uneven thickness ratio was -5% or less, but buckling was not observed in other cases. In the example shown in FIG. 6, the electric resistance pipe has a thickness of 3.2 mm as a standard. The value obtained by subtracting the minimum wall thickness from the standard wall thickness (3.2 mm) is 0.23 mm. Therefore, the uneven thickness ratio is -7.19%. In addition, it is an electrosewn steel pipe with a diameter of 165.2 mm, and the value obtained by subtracting the minimum outer diameter from the standard outer diameter (φ165.2 mm) is 0.45 mm. Therefore, the outer diameter deviation is -0.27%.

また、周方向平均値より5%以上減肉している位置と、周方向平均値より0.2%以上凹んでいる位置が重複しておらず、かつ周方向の肉厚が最小となる位置と外径が最小となる位置が±10°以上離れている場合は、より好ましいことが判明した。このようなことから、減肉と外径の凹みを調整することで、縮径加工しても座屈の発生を抑制することができることが分かった。 In addition, the position where the wall thickness is reduced by 5% or more from the circumferential average value and the position where the wall thickness is recessed by 0.2% or more from the circumferential average value do not overlap, and the position where the wall thickness in the circumferential direction is the minimum and the outside. It was found to be more preferable when the positions where the diameters were minimized were separated by ± 10 ° or more. From these facts, it was found that the occurrence of buckling can be suppressed even if the diameter is reduced by adjusting the wall reduction and the dent of the outer diameter.

ここで、電縫鋼管の製造工程について説明する。図2に示すように、電縫鋼管を製造するに際して、複数のロールを用いて、板状の帯鋼を筒状に変形させるため、この点について説明する。帯鋼はエッジベンドロールにてエッジ部(材料端部)を曲げ加工しW字状とする。その後、コンベンショナルロールでU字状とする。その後フィンパスロール、スクイズロールを用いてエッジ部を接近させて溶接し、筒状とする。その後、サイザーロールを用いて真円度を調整する。 Here, the manufacturing process of the electric resistance pipe will be described. As shown in FIG. 2, when manufacturing an electrosewn steel pipe, a plurality of rolls are used to deform the plate-shaped strip steel into a tubular shape, and this point will be described. The strip steel is bent into a W shape by bending the edge portion (material end portion) with an edge bend roll. After that, it is made into a U shape by a conventional roll. After that, the edges are brought close to each other using a fin pass roll and a squeeze roll and welded to form a tubular shape. Then, the roundness is adjusted using a sizer roll.

この際、帯鋼の中でもエッジベンドロールと当接する部位は、減肉が発生しうる場所である。この減肉は縮径加工した際の座屈と関係する。また、エッジベンドロールによる処理を複数段で行う場合、その段数が多いほど、減肉割合が大きくなる。逆に、減肉割合を小さくしようとすると、エッジベンドロールの段数を低減すればよい。エッジベンドロールは4段以内で構成されるのが一般的ではあるが、3段以上であると圧延量が増加し、圧延位置である60度付近に、有害な減肉が発生した。したがって、エッジベンドロールは2段以下にすることが好ましい。なお、後述する例においてはエッジベンドロールを1段としている。 At this time, the portion of the steel strip that comes into contact with the edge bend roll is a location where wall thinning may occur. This wall thinning is related to buckling during diameter reduction processing. Further, when the processing by the edge bend roll is performed in a plurality of stages, the larger the number of stages, the larger the wall thinning rate. On the contrary, in order to reduce the wall thinning ratio, the number of steps of the edge bend roll may be reduced. The edge bend roll is generally composed of 4 steps or less, but when the number of steps is 3 or more, the rolling amount increases and harmful wall thinning occurs near the rolling position of 60 degrees. Therefore, it is preferable that the edge bend roll is 2 steps or less. In the example described later, the edge bend roll is set to one stage.

また、電縫鋼管の真円度を調整するサイザーロールは外径の分布状態を調整するものである。このため、サイザーロールによる塑性加工量を増加させると、外径偏差に優れた電縫鋼管を製造することができる。つまり、外径の凹みが抑制された電縫鋼管を製造することができる。サイザーロールの塑性加工量は0.5〜3%程度が一般的であるが、1.2%より小さい場合、縮径加工をするには真円度が不十分となる虞があることが分かった。このため、サイザーロールの塑性加工量は1.2%以上とすることが好ましい。なお、後述する例においては、塑性加工量を確保するため、サイザーロールを3段としている。 Further, the sizer roll for adjusting the roundness of the electrosewn steel pipe adjusts the distribution state of the outer diameter. Therefore, if the amount of plastic working by the sizer roll is increased, it is possible to manufacture an electrosewn steel pipe having an excellent outer diameter deviation. That is, it is possible to manufacture an electrosewn steel pipe in which a dent of an outer diameter is suppressed. The plastic working amount of the sizer roll is generally about 0.5 to 3%, but if it is smaller than 1.2%, it has been found that the roundness may be insufficient for diameter reduction processing. Therefore, the plastic working amount of the sizer roll is preferably 1.2% or more. In the example described later, the sizer roll has three stages in order to secure the amount of plastic working.

偏肉と外径偏差を好ましい範囲にするには、エッジベンドロールは2段以下にするとともに、サイザーロールの塑性加工量は1.2%以上とすることが好ましい。 In order to keep the uneven thickness and the outer diameter deviation in a preferable range, it is preferable that the edge bend roll is 2 steps or less and the plastic working amount of the sizer roll is 1.2% or more.

図3に、実施形態に該当する製造方法による電縫鋼管の厚みと外径に関する周方向の分布例を表す図を示す。より具体的には、図6に示した例と同じく、直径が165.2mmであり、厚みが3.2mmであるSTK540の電縫鋼管である。なお、縦方向に-0.5から0.5まで記した数値は外径偏差である。また、外周に沿って記された数値は、電縫鋼管の中心位置からみて溶接箇所と測定箇所がなす角度である。この例では、略均等な厚みと外径を確保できており、電縫鋼管の周方向平均値より5%以上減肉している位置と、周方向平均値より0.2%以上凹んでいる位置が重複するようなことは発生していない。また、周方向の肉厚が最小となる位置と外径が最小となる位置が±10°以上離れている。この電縫鋼管を18乃至20%縮径しても座屈の発生は見られなかった。なお、本例における基準となる肉厚から最小となる肉厚を引いた値は0.13mmである。したがって、偏肉割合は-4.06%である。また、基準となる外径から最小となる外径を引いた値は0.23mmである。したがって、外径偏差は-0.14%である。 FIG. 3 shows a diagram showing an example of distribution in the circumferential direction regarding the thickness and outer diameter of the electrosewn steel pipe by the manufacturing method corresponding to the embodiment. More specifically, as in the example shown in FIG. 6, the STK540 electric resistance pipe has a diameter of 165.2 mm and a thickness of 3.2 mm. The numerical values written from -0.5 to 0.5 in the vertical direction are the outer diameter deviations. Further, the numerical value written along the outer circumference is the angle formed by the welded portion and the measured portion when viewed from the center position of the electrosewn steel pipe. In this example, a substantially uniform thickness and outer diameter can be secured, and the position where the wall thickness is reduced by 5% or more from the circumferential average value of the electrosewn steel pipe and the position where the thickness is recessed by 0.2% or more from the circumferential average value are There is no duplication. In addition, the position where the wall thickness is minimized in the circumferential direction and the position where the outer diameter is minimized are separated by ± 10 ° or more. No buckling was observed even when the diameter of this electric resistance pipe was reduced by 18 to 20%. The value obtained by subtracting the minimum wall thickness from the standard wall thickness in this example is 0.13 mm. Therefore, the uneven thickness ratio is -4.06%. The value obtained by subtracting the minimum outer diameter from the standard outer diameter is 0.23 mm. Therefore, the outer diameter deviation is -0.14%.

図4には、図3とは異なる製造方法による電縫鋼管の厚みと外径に関する周方向の分布例を表す図を示す。この電縫鋼管は、図3の例よりもやや厚みにも外形にもばらつきがある。しかし、周方向の肉厚が最小となる位置と外径が最小となる位置が±10°以上離れているという条件を満たしている。この電縫鋼管を縮径しても座屈の発生は見られなかった。 FIG. 4 shows a diagram showing an example of distribution in the circumferential direction regarding the thickness and outer diameter of the electrosewn steel pipe by a manufacturing method different from that of FIG. This electric resistance steel pipe has a slight variation in thickness and outer shape as compared with the example of FIG. However, the condition that the position where the wall thickness in the circumferential direction is the minimum and the position where the outer diameter is the minimum are separated by ± 10 ° or more is satisfied. No buckling was observed even when the diameter of this electric resistance pipe was reduced.

以上、一つの例を中心に実施形態を説明したが、本発明は、以上の実施形態には限定されることは無く、本発明の趣旨を逸脱しない範囲で適応可能なことは勿論のことである。 Although the embodiments have been described above with reference to one example, the present invention is not limited to the above embodiments, and it goes without saying that the present invention can be applied without departing from the spirit of the present invention. is there.

Claims (4)

周方向平均値より5%以上減肉している位置と、溶接部を頂点とした±90°の範囲における周方向平均値より外径が0.2%以上凹んでいる位置が重複していないことを特徴とする縮径加工強度に優れた電縫鋼管。 Make sure that the position where the wall thickness is reduced by 5% or more from the circumferential average value and the position where the outer diameter is recessed by 0.2% or more from the circumferential average value in the range of ± 90 ° with the welded part as the apex do not overlap. Electrified steel pipe with excellent reduced diameter processing strength. 肉厚が最小となる周方向の位置と、溶接部を頂点とした±90°の範囲における外径が最小となる位置が±10°以上離れていることを特徴とする縮径加工強度に優れた電縫鋼管。 Excellent diameter reduction processing strength characterized by the fact that the position in the circumferential direction where the wall thickness is the minimum and the position where the outer diameter is the minimum in the range of ± 90 ° with the welded part as the apex are separated by ± 10 ° or more. Welded steel pipe. 周方向平均値より5%以上減肉している位置と、溶接部を頂点とした±90°の範囲における周方向平均値より外径が0.2%以上凹んでいる位置が重複しておらず、かつ周方向の肉厚が最小となる位置と外径が最小となる位置が±10°以上離れていることを特徴とする縮径加工強度に優れた電縫鋼管。 The position where the wall thickness is reduced by 5% or more from the circumferential average value and the position where the outer diameter is recessed by 0.2% or more from the circumferential average value in the range of ± 90 ° with the welded part as the apex do not overlap. A welded steel pipe with excellent diameter reduction processing strength, characterized in that the position where the wall thickness is minimized in the circumferential direction and the position where the outer diameter is minimized are separated by ± 10 ° or more. エッジベンドロールの段数が2段以下であり、サイジングロールでの塑性加工量が1.2%以上であることを特徴とする縮径加工強度に優れた電縫鋼管の製造方法。 A method for manufacturing an electrosewn steel pipe having excellent diameter reduction processing strength, characterized in that the number of stages of the edge bend roll is 2 or less and the amount of plastic working on the sizing roll is 1.2% or more.
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