JPH04339517A - Hot forming method for large diameter rectangular steel tube - Google Patents
Hot forming method for large diameter rectangular steel tubeInfo
- Publication number
- JPH04339517A JPH04339517A JP13855791A JP13855791A JPH04339517A JP H04339517 A JPH04339517 A JP H04339517A JP 13855791 A JP13855791 A JP 13855791A JP 13855791 A JP13855791 A JP 13855791A JP H04339517 A JPH04339517 A JP H04339517A
- Authority
- JP
- Japan
- Prior art keywords
- steel pipe
- heating
- steel tube
- forming
- steel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 268
- 239000010959 steel Substances 0.000 title claims abstract description 268
- 238000000034 method Methods 0.000 title claims description 55
- 238000010438 heat treatment Methods 0.000 claims abstract description 150
- 239000002803 fossil fuel Substances 0.000 claims abstract description 30
- 238000003466 welding Methods 0.000 claims abstract description 25
- 239000002131 composite material Substances 0.000 claims abstract description 6
- 230000007246 mechanism Effects 0.000 abstract description 20
- 238000000137 annealing Methods 0.000 abstract description 8
- 239000000463 material Substances 0.000 description 72
- 230000009466 transformation Effects 0.000 description 20
- 230000008569 process Effects 0.000 description 13
- 230000002093 peripheral effect Effects 0.000 description 10
- 238000005482 strain hardening Methods 0.000 description 10
- 238000010276 construction Methods 0.000 description 9
- 230000006866 deterioration Effects 0.000 description 9
- 230000000694 effects Effects 0.000 description 9
- 238000012545 processing Methods 0.000 description 9
- 230000005611 electricity Effects 0.000 description 8
- 239000007789 gas Substances 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 8
- 230000008901 benefit Effects 0.000 description 7
- 238000001816 cooling Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000005452 bending Methods 0.000 description 5
- 230000006698 induction Effects 0.000 description 5
- 238000012423 maintenance Methods 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 238000007796 conventional method Methods 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 239000000470 constituent Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 239000012467 final product Substances 0.000 description 3
- 238000007726 management method Methods 0.000 description 3
- 238000013459 approach Methods 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 238000012937 correction Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 238000004513 sizing Methods 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- 229910000926 A-3 tool steel Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 235000011911 Echinocactus horizonthalonius horizonthalonius Nutrition 0.000 description 1
- 235000011499 Ferocactus hamatacanthus Nutrition 0.000 description 1
- 244000231499 Turks head Species 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000001151 other effect Effects 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000007788 roughening Methods 0.000 description 1
- 238000005488 sandblasting Methods 0.000 description 1
- 238000005480 shot peening Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は、大径角形鋼管の連続的
熱間成形工法にかかり、より詳しくは、肉厚の帯鋼板を
、その長手方向に平行して冷間塑性加工により折曲げて
両側縁を突合わせ溶接し断面閉曲線よりなる大径鋼管を
連続成形した後、前記鋼管を全体的に加熱して、そのま
ま角形断面成形工程に送り、熱間加工によって前記鋼管
断面形を角形に形成するようにしたことを特徴とするワ
ンシームの大径角形鋼管、特に、そのコーナー部の材質
の残留内部応力を解消し、靭性を改善するようにした肉
厚角形鋼管の熱間成形工法に関するものである。[Industrial Application Field] The present invention relates to a continuous hot forming method for large-diameter square steel pipes, and more specifically, a thick steel strip is bent by cold plastic working parallel to its longitudinal direction. After butt-welding both side edges and continuously forming a large-diameter steel pipe with a closed curve in cross section, the steel pipe is heated as a whole and sent as it is to a square cross-section forming process, and the cross-sectional shape of the steel pipe is made into a square cross-section by hot working. This invention relates to a hot forming method for one-seam large-diameter rectangular steel pipes, in particular, for eliminating residual internal stress in the material at the corners and improving toughness. It is.
【０００２】0002
【従来の技術】鉄骨構造物のコラムとして需要が大きい
肉厚大径角形鋼管の冷間加工による量産方法は従来、略
、次のような工法が採用されている。■熱間圧延コイル
を、レベラーに掛けてフラットな帯鋼板にして、その両
側縁を幅決め・開先加工する。■前記帯鋼板を、ブレー
クダウン、クラスター、フィンパススタンド等加工段に
直列に通して移送し、その間、鋼板を順次、成形して直
角断面を円形に近い形状に成形した後、■高周波抵抗ま
たは誘導溶接装置、スクイズロールを経て丸鋼管を構成
する。■前記丸鋼管を、放冷してから、サイザー、スケ
アリングスタンド、タークスヘッド等を経て、断面角形
に形成し、大径角形鋼管を製造していた。BACKGROUND OF THE INVENTION Conventionally, the following methods have been adopted for the mass production of thick, large-diameter rectangular steel pipes, which are in great demand as columns for steel structures, by cold working. ■The hot-rolled coil is passed through a leveler to form a flat steel strip, and both edges are width-determined and beveled. ■The steel strip is transferred in series through processing stages such as breakdown, cluster, and fin pass stands, during which the steel plates are sequentially formed to form a right-angled cross section into a nearly circular shape. Round steel pipes are constructed through induction welding equipment and squeeze rolls. (2) The round steel pipe was left to cool, and then passed through a sizer, scaling stand, Turk's head, etc., and then formed into a square cross section to produce a large diameter square steel pipe.
【０００３】上述工法においては、角形鋼管成形のため
に、平坦ないし円弧状曲面の肉厚鋼板を冷間塑性加工に
よって略、９０゜折曲げる工程が含まれている。ところ
で、肉厚鋼板を冷間で、略、９０゜折曲げ加工を施した
場合には、前記折曲げ部の鋼板断面における中立面を境
にして、その外側材料には引張り力が、内側材料には圧
縮力が働きながら変形が行われるため、当該個所には所
要のＲを施しているにもかかわらず、素材が備える弾性
限界を越えて塑性変形が進み、変形個所、特に隅角部材
質の機械的特性が劣化し、脆性破壊を生じるおそれが絶
無とはいえない。[0003] The above-mentioned method includes a step of bending a thick steel plate having a flat or arcuate curved surface approximately 90 degrees by cold plastic working in order to form a square steel pipe. By the way, when a thick steel plate is cold bent approximately 90 degrees, a tensile force is applied to the outer material at the neutral plane of the cross section of the steel plate at the bent portion, and Because the material is deformed while compressive force is acting on it, plastic deformation progresses beyond the elastic limit of the material, even though the required R is applied to the relevant part, resulting in deformation of the deformed part, especially at the corners. It cannot be said that there is no absolute possibility that the mechanical properties of the material will deteriorate and brittle fracture will occur.
【０００４】この種の大径角形鋼管をコラムとして使用
する鉄骨構造物、建築物等は一般に、一度施工した後は
、長期にわたり自重および構造物に付帯する重量を歪な
く支承することは勿論、地震、台風等の外力による過酷
な繰返し荷重にも安全に耐えることが要求され、しかも
、これらのコラムは原則的に交換・補修が可能でないと
いった状態で施工されている場合が多い。近来、冷間折
曲げ加工により成形した、この種の大径角形鋼管を建築
構造物のコラムとして多用し、また、中・高層建築物の
コラムとしても使用されるに及んで、上述の事情に鑑み
鋼管成形時における前記冷間加工に基づく材質の劣化が
問題視されるようになった。そして、最近、有識者の間
では、この種の冷間塑性加工による大径角形鋼管は、そ
の用途の大部分を占める鋼構造物の主体構造材として適
切なのか、といった懸念も生じているようである。[0004] Steel structures, buildings, etc. that use this type of large-diameter rectangular steel pipes as columns generally have the ability to support their own weight and the weight attached to the structure for a long period of time without distortion once they are constructed. They are required to safely withstand severe repeated loads caused by external forces such as earthquakes and typhoons, and in many cases these columns are constructed in such a way that they cannot be replaced or repaired in principle. In recent years, this type of large-diameter rectangular steel pipe formed by cold bending has been frequently used as columns in architectural structures, and also as columns in medium- and high-rise buildings. In view of this, material deterioration due to the cold working during steel pipe forming has become a problem. Recently, there seems to be concern among experts as to whether large-diameter rectangular steel pipes produced by this type of cold plastic processing are appropriate as the main structural material for steel structures, which account for the majority of their uses. be.
【０００５】冷間塑性加工大径角形鋼管が内包する、こ
の種の材質的問題点を解決するために、従来、■オフラ
インで、既製の電縫鋼管・シームレスパイプなどを、油
、ガス等の化石燃料または電気エネルギーにより加熱し
、これを複数段の圧延機を通して断面角形に成形するこ
とが行われている。上記工法によるときは、製品の品質
は良好であるが、鋼管の両端部が変形するため歩止りが
悪いとか、鋼管を一本宛加工するので生産が低い。また
、鋼管全体を高温加熱するようにするから、焼きなまし
コストが掛かる。■成形ずみの大径角形鋼管を焼鈍炉に
入れて、材質中の残留応力が略、除去されるまで全体的
に加熱した後、焼なます。この場合、鋼材のＡ１ 変態
点まで加熱する工法と、Ａ３ 変態点まで上げて加熱す
る工法とがある。[0005] In order to solve this type of material problem inherent in cold plastic-formed large diameter rectangular steel pipes, conventionally, ready-made electric resistance welded steel pipes, seamless pipes, etc., were treated off-line with oil, gas, etc. It is heated using fossil fuel or electric energy and then passed through a multi-stage rolling mill to form it into a rectangular cross-section. When using the above method, the quality of the product is good, but the yield is poor because both ends of the steel pipe are deformed, and the production is low because each steel pipe is processed one by one. Furthermore, since the entire steel pipe is heated to a high temperature, annealing costs are incurred. ■The formed large diameter rectangular steel pipe is placed in an annealing furnace and heated until the residual stress in the material is almost completely removed, and then annealed. In this case, there are two methods: heating the steel material up to its A1 transformation point, and heating it up to its A3 transformation point.
【０００６】■熱間圧延コイルをレベラーにかけ、各種
成形ロールスタンドおよび高周波溶接装置を通して冷間
塑性加工により丸鋼管に成形した後、同鋼管をインライ
ンで電気（誘導）、ガスまたは油等の化石燃料により加
熱して、複数段の熱間成形ロールを通し、これを断面角
形の鋼管に成形して冷却し、製品にする。上述工法は、
インライン加熱なので、スムーズに行けば、前述■の場
合よりも歩止りが良く、生産性は上るが、一度、ライン
が故障したり、溶接欠陥等により停止すると、著しく生
産性、歩止りが悪くなる。[0006] After applying the hot rolled coil to a leveler and forming it into a round steel pipe by cold plastic working through various forming roll stands and high frequency welding equipment, the steel pipe is in-line heated by electricity (induction), fossil fuels such as gas or oil, etc. The pipe is heated, passed through multiple stages of hot forming rolls, formed into a steel tube with a square cross section, and cooled to form a product. The above construction method is
Since it is in-line heating, if it goes smoothly, the yield will be better than in case ① above, and productivity will increase, but once the line breaks down or stops due to welding defects, productivity and yield will deteriorate significantly. .
【０００７】■また、インラインで、ガス、油等の化石
燃料を利用する加熱炉を設備する場合は、鋼管の成形ス
ピードが速い（高周波溶接により良好な溶接継手を得る
ためには、ある程度の溶接スピードが要求される）ため
に、鋼管材料内の残留応力が完全に解消する鋼材のＡ３
変態点温度まで鋼管を加熱するのにラインの中途に２
００ｍ〜３００ｍ長さの加熱炉を設置するスペースが必
要になるから、製造ラインが長大になり過ぎて立地条件
の選定が困難になるとか、設備投資額が予想以上に膨ら
むおそれがある。加えて、ガス、油等の化石燃料を丸鋼
管の加熱に利用すると、熱源を鋼管の内側に入れること
ができないから、素材を均一に加熱することがむずかし
く、鋼管の温度管理の面で問題があり、結局、均等な品
質の製品が得られないこともあり得る。[0007] Also, when installing an in-line heating furnace that uses fossil fuels such as gas and oil, the forming speed of steel pipes is faster (in order to obtain a good welded joint by high-frequency welding, a certain amount of welding is required). A3 steel material that completely eliminates residual stress within the steel pipe material due to high speed requirements)
2 in the middle of the line to heat the steel pipe to the transformation point temperature
Since a space is required to install a heating furnace with a length of 00 m to 300 m, there is a risk that the production line will become too long, making it difficult to select location conditions, or that the amount of capital investment will increase more than expected. In addition, when fossil fuels such as gas and oil are used to heat round steel pipes, the heat source cannot be placed inside the steel pipes, making it difficult to heat the material uniformly and causing problems in terms of temperature control of the steel pipes. In the end, it may not be possible to obtain products of uniform quality.
【０００８】さらに、化石燃料による加熱炉は一般に、
熱効率が極めて低い上に排ガス、廃熱に基づく公害対策
を構じる必要が生じることもある。なお、化石燃料の燃
焼装置および加熱炉の保守、管理のためにも、人手を要
する。ただし、燃料コストが安く、運搬も比較的に容易
で、立地条件の如何にかかわらず入手が楽であるメリッ
トがあることが認められる。■一方、電気エネルギーを
利用した加熱装置は、加熱のためのスペースが小さくて
済み、均一加熱並びに加熱温度の管理を徹底することが
できる利点があるものの、電力コストが高くかかり、立
地条件によっては必要とする大容量の電力の入手が困難
である。要するに発送電設備が用意されていない場合が
ある。等々の技術的問題点があることが知られている。Furthermore, fossil fuel heating furnaces generally have
In addition to extremely low thermal efficiency, it may be necessary to take measures against pollution based on exhaust gas and waste heat. Note that maintenance and management of fossil fuel combustion equipment and heating furnaces also require manpower. However, it is recognized that fuel costs are low, transportation is relatively easy, and it is easy to obtain regardless of location. ■On the other hand, heating devices that use electrical energy have the advantage of requiring only a small space for heating and allowing for uniform heating and thorough control of the heating temperature, but they require high electricity costs and may It is difficult to obtain the large amount of electricity needed. In other words, there are cases where power transmission equipment is not available. It is known that there are technical problems such as:
【０００９】[0009]
【発明が解決しようとする課題】本発明工法の目的は、
上述したような事情を背景にして開発されたもので、角
形鋼管断面の平板部分の靭性を改善し、コーナー部分の
内部応力を許容残留応力以下に除去し、全体的材質を均
一に、かつ、安定した品質を備えた、ワンシーム大径角
形鋼管を製造する工法を提供することである。また、本
発明工法の別の目的は、従来、知られているオフライン
、インラインの鋼管加熱による均質な角形鋼管の成形工
法に内在する上述問題点を可及的に解消できる新規な熱
間成形工法を開発することにある。[Problem to be solved by the invention] The purpose of the construction method of the present invention is to
It was developed against the background of the above-mentioned circumstances, and improves the toughness of the flat section of the square steel pipe cross section, removes the internal stress at the corner to below the allowable residual stress, makes the overall material uniform, and The purpose of the present invention is to provide a method for manufacturing one-seam large-diameter square steel pipes with stable quality. Another objective of the method of the present invention is to create a new hot forming method that can eliminate as much as possible the above-mentioned problems inherent in the conventional methods of forming homogeneous square steel pipes by off-line and in-line steel pipe heating. The goal is to develop
【００１０】0010
【課題を解決するための手段】本発明工法は、上述の目
的を達成するために、以下に述べるとおりの各構成要件
を具備する。
（１）帯鋼板を長手方向直角断面で丸形に成形し、その
両側縁を突合わせ溶接して形成した連続丸鋼管の外周全
体を、ガス、油等の化石燃料を熱源とした加熱と電気エ
ネルギーによる高周波加熱とにより複合加熱して丸鋼管
全体を均等な所要温度に維持するよう温度管理しながら
、前記鋼管を角形成形用ロールスタンドに移送すること
を特徴とする大径角形鋼管の熱間成形工法。
（２）帯鋼板を長手方向直角断面で丸形に成形し、その
両側縁を突合わせ溶接して形成した連続丸鋼管の外周全
体を、ガス、油等の化石燃料熱源または電気エネルギー
による高周波加熱装置により、あるいは前記両加熱手段
の複合加熱により加熱すると共に、コーナー予定個所付
近のみを高周波加熱装置または化石燃料を利用したバー
ナ等による部分加熱を施すと共に、前記鋼管を角形成形
用ロールスタンドに移送することを特徴とする大径角形
鋼管の熱間成形工法。[Means for Solving the Problems] In order to achieve the above-mentioned object, the construction method of the present invention has the following constituent elements. (1) The entire outer periphery of a continuous round steel tube, which is formed by forming a strip steel plate into a round shape with a cross section perpendicular to the longitudinal direction and butt-welding both sides of the steel plate, is heated using fossil fuels such as gas and oil as a heat source. Hot processing of large-diameter square steel pipes, characterized in that the steel pipes are transferred to a roll stand for square forming while temperature-controlled to maintain the entire round steel pipe at a uniform required temperature through composite heating using high-frequency heating using energy. Molding method. (2) The entire outer periphery of a continuous round steel pipe, which is formed by forming a strip steel plate into a round shape with a cross section perpendicular to the longitudinal direction and butt-welding both side edges, is heated by high-frequency heating using a fossil fuel heat source such as gas or oil or electric energy. The steel pipe is heated by a heating device or by combined heating of both heating means, and the area near the planned corner is partially heated by a high-frequency heating device or a burner using fossil fuel, and the steel pipe is transferred to a roll stand for square forming. A hot forming method for large diameter square steel pipes.
【００１１】[0011]
【作用】（１）以上のような現状に鑑みて、本発明工法
では、鋼管の複合加熱法、つまり、鋼管に対する立上り
加熱および大方の加熱は、専ら化石燃料により加熱し、
微妙な温度管理を必要とする最終加熱を電力を利用した
高周波加熱手段を用いて行うようにして、大量にカロリ
ーが必要な鋼管の初期加熱には比較的、大量に入手が容
易で、コストの低い化石燃料を利用し、温度管理の厳し
い最終加熱には、出力調整が容易だがコストが高い電力
を用い、全体として鋼管の焼鈍コストを低下させ、にも
かかわらず鋼管の最終加熱温度を正しく調節することが
できるようにする。[Function] (1) In view of the above-mentioned current situation, in the construction method of the present invention, the composite heating method for steel pipes, that is, the start-up heating and most of the heating for steel pipes, is performed exclusively by fossil fuel,
The final heating, which requires delicate temperature control, is performed using high-frequency heating means using electric power, and the initial heating of steel pipes, which requires a large amount of calories, is relatively easy to obtain in large quantities and is inexpensive. By using low-cost fossil fuels and for final heating with strict temperature control, we use electricity that is easy to adjust the output but is expensive, reducing the overall cost of annealing steel pipes, and yet correctly adjusting the final heating temperature of steel pipes. be able to do so.
【００１２】（２）のみならず、化石燃料の燃焼加熱の
みでは、鋼管を所要温度まで加熱するのに前述のとおり
長大な加熱炉の設備が必要になって、生産ラインの立地
条件の選択が困難になるおそれがあるが、前記加熱手段
に直列に電力エネルギーを利用した高周波加熱装置を設
備することによって、狭いスペース内に大容量の加熱装
置を設置することができるので、鋼管加熱装置の設備全
長を大幅に短縮することが可能となる。この場合は、必
ずしも化石燃料による加熱手段を予備加熱に利用するこ
とを要さず、たとえば高周波加熱装置を加熱装置の初期
加熱側に設備し、その出力は、丸鋼管が後段の加熱装置
を離れるときの温度を検知して制御することもできる。
高周波加熱装置を前段に設備した場合には、前記高周波
加熱装置には、常時、常温の丸鋼管が供給されるから、
装置の耐熱および発生熱除去方法に通常要求される以上
の注意を払う必要がなく、装置の保守・管理および耐用
年数を延長できるメリットも生じる。[0012] In addition to (2), if only fossil fuel combustion heating is used, a long heating furnace equipment is required to heat the steel pipe to the required temperature, making it difficult to choose the location of the production line. Although this may be difficult, by installing a high-frequency heating device that uses electric energy in series with the heating means, it is possible to install a large-capacity heating device in a narrow space. It becomes possible to significantly shorten the overall length. In this case, it is not necessary to use fossil fuel heating means for preheating; for example, a high-frequency heating device is installed on the initial heating side of the heating device, and its output is determined by the round steel pipe leaving the subsequent heating device. It can also be controlled by detecting the temperature. When a high-frequency heating device is installed in the first stage, round steel pipes at room temperature are always supplied to the high-frequency heating device.
There is no need to pay more attention than is normally required to the heat resistance of the equipment and the method for removing generated heat, and there is also the advantage of extending the maintenance and management of the equipment and its service life.
【００１３】（３）上記丸鋼管の全体的または部分加熱
については、鋼材に残留する内部応力を解消ないし除去
するＡ１ 変態点まで鋼管を加熱する工法と、前記鋼材
の組織まで変えるＡ３ 変態点まで加熱する工法とが考
えられる。■最終加熱温度が、たとえば鋼材のＡ１ 変
態点付近までであっても、その温度管理および均一加熱
のために、鋼管の終段加熱装置は、電力による加熱を利
用することができる。上述したメリットは、当該加熱装
置も当然具備するものであり、帯鋼板を折曲げ溶接した
丸鋼管材質に残留する内部応力および溶接歪を殆んど除
去したままの加熱状態で、角形成形ロールスタンドに移
送され、そこで丸鋼管は成形ロールによる熱間加工によ
って徐々に断面角形に成形される。丸鋼管は大径であっ
て肉厚鋼板よりなり熱容量が大であるから、鋼管が角形
成形ロール工程を通過して正規形状の角形鋼管が形成さ
れた後もなお、高温状態にある。(3) Regarding the above-mentioned whole or partial heating of the round steel pipe, A1 is a method of heating the steel pipe to the transformation point to dissolve or remove the internal stress remaining in the steel material, and A3 is a method of heating the steel pipe to the transformation point, and A3 is a method of heating the steel pipe to the transformation point. A heating method is considered. (2) Even if the final heating temperature is, for example, close to the A1 transformation point of the steel material, the final stage heating device for steel pipes can utilize electric heating for temperature control and uniform heating. The above-mentioned advantages are naturally provided by the heating device, and the square-forming roll stand can be heated in a heated state with almost all the internal stress and welding distortion remaining in the round steel pipe material made by bending and welding the strip steel plate. There, the round steel tube is gradually formed into a square cross section by hot working with forming rolls. Since a round steel pipe has a large diameter and is made of a thick steel plate and has a large heat capacity, it remains in a high temperature state even after the steel pipe passes through the square forming roll process to form a square steel pipe with a regular shape.
【００１４】■複合加熱のメリットは、加熱装置の最終
段に高周波加熱装置を設備した上述■の場合のみに限ら
れず、高周波加熱装置を、その前段側に施した場合にも
同様に得られることは勿論である。■丸鋼管をＡ３ 変
態点付近まで加熱することより、冷間塑性加工により劣
化した鋼材の結晶組織の再結晶をうながし、鋼材内部の
残留応力を減少させることができるが、従来工法による
ときには前述のようなデメリットが存在する。そして、
前述■または■の場合に比べＡ１ 変態点よりも鋼材を
高温に加熱するために加熱設備が大型になることは避け
難いし、また、加熱コストも増加する。本発明工法によ
れば、供給可能な電力を利用した加熱容量では不足な分
を、化石燃料を用いた加熱装置によって補うよう計画す
ることで、エネルギーの入手事情を顧慮することなく、
また、それによって設備の長大化を防止することができ
るために、立地条件の選択が比較的に容易になる等々の
メリットが得られる効用は、さきの鋼管材料のＡ１ 変
態点加熱の場合と同様である。[0014] ■The advantages of composite heating are not limited to the above-mentioned case (■) in which a high-frequency heating device is installed at the final stage of the heating device, but can also be obtained when the high-frequency heating device is installed at the previous stage. Of course. ■By heating a round steel pipe to around the A3 transformation point, it is possible to promote the recrystallization of the crystal structure of the steel material deteriorated by cold plastic working and reduce the residual stress inside the steel material, but when using the conventional method, the above-mentioned There are such disadvantages. and,
Compared to the case of (1) or (2) above, it is difficult to avoid that the heating equipment becomes larger in order to heat the steel material to a higher temperature than the A1 transformation point, and the heating cost also increases. According to the construction method of the present invention, by planning to supplement the insufficient heating capacity using available electric power with a heating device using fossil fuels, without considering the circumstances of obtaining energy,
In addition, since it is possible to prevent the equipment from becoming too long, it is relatively easy to select the location conditions, and the benefits are the same as in the case of A1 transformation point heating of steel pipe materials. It is.
【００１５】しかし、これによって成形された大径角形
鋼管の材質、特にその溶接ライン付近および各コーナー
部に残留する内部応力、加工硬化は、略、完全に除去す
ることができ、また、熱間成形による精度の高い角形鋼
管が得られるなど、均質で、かつ、高級な大径角形鋼管
を提供することが可能となる。■要するに鋼管断面の角
形成形工程を熱間加工によって行うようにしたから、成
形が容易であって鋼管周壁の四個所を略９０゜に折曲げ
ることにより生じる鋼管隅角部の加工硬化、残留応力並
びに鋼材の突合わせ溶接に基づく残留歪が実用上差支え
ない程度に除去され成形鋼管材内に残留応力が存在する
おそれがない。または、コーナー部の材質の劣化は殆ん
ど回復する。However, the internal stress and work hardening that remain in the material of the large diameter rectangular steel pipe formed by this method, especially in the vicinity of the weld line and at each corner, can be almost completely removed, and the hot It becomes possible to provide a homogeneous and high-grade large-diameter square steel pipe, such as a square steel pipe with high precision obtained by forming. ■In short, since the process of forming the corners of the steel pipe cross section is carried out by hot working, forming is easy, and work hardening and residual stress in the corners of the steel pipe are caused by bending the circumferential wall of the steel pipe at approximately 90 degrees. In addition, residual strain due to butt welding of steel materials is removed to a practically acceptable extent, and there is no risk of residual stress existing within the formed steel pipe material. Alternatively, the deterioration of the material at the corner portion is almost completely recovered.
【００１６】■従来、実施されているワンシーム丸鋼管
から角形鋼管を成形する工法においては、丸鋼管形成時
における高周波溶接による鋼材の加熱温度自然放冷用の
長いスペースが角形管成形ロール工程前に設けられてい
るが、本発明工法の鋼管加熱装置は、前記スペースを利
用して設備することができるから、本発明工法は、従来
装置に比べて極端に長大なスペースを必要としない。■
したがって、本発明工法によれば、昨今問題視されてい
る大径角形鋼管の隅角部塑性変形に基づく鋼管コーナー
部の材質劣化の欠陥を、実用上差支えない程度に除去す
ることができる。しかも、従来工法にみられるようなオ
フラインにおける、化石燃料を熱源とする焼鈍炉を設備
するものに比べて、本発明工法の場合は生産性が高く、
実質的に鋼管鋼材を焼鈍している割には、それによるコ
ストアップが少ない。また、インラインに施した従来工
法における加熱炉に比べ設備スペースが小さくて済み、
鋼材の加熱温度の管理および均一加熱の点で優れており
、さらに成形加工を高精度で施すことができるから、結
局、本発明工法によれば、高品質かつ、均一な大径角形
鋼管を製造することができる。[0016] In the conventional method of forming square steel pipes from one-seam round steel pipes, the heating temperature of the steel material by high-frequency welding during the formation of round steel pipes requires a long space for natural cooling before the square pipe forming roll process. However, since the steel pipe heating device of the present invention method can be installed using the space, the present invention method does not require an extremely large space compared to the conventional device. ■
Therefore, according to the construction method of the present invention, it is possible to eliminate the defect of material deterioration in the corner portion of a steel pipe due to corner plastic deformation of a large diameter rectangular steel pipe, which has been viewed as a problem in recent years, to an extent that does not cause any practical problems. Moreover, compared to the conventional method, which uses an off-line annealing furnace that uses fossil fuel as a heat source, the method of the present invention has higher productivity.
Although the steel pipe material is actually annealed, the cost increase is small. In addition, the equipment space is smaller compared to the conventional in-line heating furnace.
Since the method of the present invention is superior in terms of controlling the heating temperature and uniform heating of steel materials, and can perform forming processing with high precision, it is possible to produce high-quality, uniform large-diameter rectangular steel pipes using the method of the present invention. can do.
【００１７】（４）市場に流通している大径角形鋼管に
対し問題視されている材質的欠陥は、鋼管成形工程中の
冷間折曲げ加工に基づく鋼管コーナー部の材質の加工硬
化、残留応力の存在等、局部材質の劣化による構造材の
弱体化である。■そこで本第２発明工法においては、ワ
ンシーム丸鋼管を角形成形ロール加工に送込む直前に、
少なくとも鋼管周面のコーナー予定個所付近を鋼材のＡ
３ 変態点まで加熱することによって前述（３）−■場
合に近い効果を奏することを期待している。ただし、丸
鋼管を、角形断面に成形するのにコーナー予定個所付近
のみを、より加熱しただけでは、鋼管周壁材料の剛さが
不均一に過ぎて、そのまま成形ロールに通しても精度の
高い大径角形鋼管を形成することができない。(4) Material defects that are considered problematic in large-diameter square steel pipes on the market include work hardening and residual material at the corners of the steel pipe due to cold bending during the steel pipe forming process. This is the weakening of structural materials due to deterioration of local materials, such as the presence of stress. ■Therefore, in the second invention method, immediately before sending the one-seam round steel pipe to the square forming roll processing,
At least the vicinity of the planned corner of the circumferential surface of the steel pipe is
3. By heating to the transformation point, it is expected that an effect similar to the case (3)-■ described above will be produced. However, in order to form a round steel pipe into a rectangular cross section, heating only the area near the intended corner will result in the stiffness of the steel pipe peripheral wall material being too uneven, and even if it is passed through the forming rolls as it is, it will not be possible to create a highly accurate size. It is not possible to form square diameter steel pipes.
【００１８】このため、鋼管周壁のコーナー予定個所を
加熱すると共に、あらかじめ鋼管全体を、鋼材のＡ１
変態点近くまで加熱し、これによって鋼管の周壁材の剛
さの不均一をならし、加えて鋼管の溶接ライン付近に生
じている溶接歪の除去、丸鋼管成形に基づく鋼材の加工
硬化の解消を行うようにし、丸鋼管の断面角形成形加工
に当たり鋼材の熱間成形を可能とする。■第２発明工法
によれば、大径角形鋼管の品質については、略鋼管全体
のＡ３ 変態点加熱の場合に近い効果が得られる割に、
鋼管加熱装置自体は、Ａ１ 変態点加熱のものと略、同
等で、加熱設備、加熱に必要なカロリーもＡ１ 変態点
加熱と略、同等であるから、加熱焼鈍による鋼管製品の
コストダウンが進む。For this purpose, in addition to heating the planned corners of the peripheral wall of the steel pipe, the entire steel pipe is
Heating near the transformation point, this smoothes out the uneven stiffness of the surrounding wall material of the steel pipe, removes welding distortion that occurs near the weld line of the steel pipe, and eliminates work hardening of the steel material due to round steel pipe forming. This makes it possible to hot form steel materials when forming round steel pipes into cross-section corners. ■According to the second invention method, regarding the quality of large-diameter square steel pipes, although the effect is similar to that achieved by heating the entire steel pipe to the A3 transformation point,
The steel pipe heating device itself is almost the same as that for A1 transformation point heating, and the heating equipment and calories required for heating are also almost the same as A1 transformation point heating, so the cost of steel pipe products by heat annealing can be reduced.
【００１９】なお、丸鋼管の全体的加熱については上述
（３）−■または■に記載のような工法を利用すること
もでき、鋼管の全体加熱後に、そのコーナー予定個所の
みの加熱、すなわち部分加熱を施すようにすれば、鋼材
予熱後の部分加熱であるために、その加熱エネルギーは
比較的に少なくて済む。また、丸鋼管の部分加熱装置に
も化石燃料を熱源として利用するもの、高周波加熱装置
を用いるものとがあり得るが、高周波加熱による場合の
方が鋼材の温度管理、鋼材内の熱分布状態を制御し易い
ことが知られている。[0019] For heating the entire round steel pipe, it is also possible to use the method described in (3)-■ or ■ above. If heating is performed, the heating energy is relatively small because it is partial heating after preheating the steel material. In addition, partial heating devices for round steel pipes may use fossil fuels as a heat source or high-frequency heating devices, but high-frequency heating is better for controlling the temperature of the steel material and controlling the heat distribution within the steel material. It is known to be easy to control.
【００２０】[0020]
【実施例】以下に、本発明工法および前記工法を実施す
るための設備を具えた大径角形鋼管の製造ラインの一実
施例につき図面に沿って説明するが、右鋼管製造ライン
を構成する各セクションの具体的構造部材は、本出願当
時の当業界における公知技術の範囲内で任意な部分的変
形が可能であるから、格別の理由を示すことなしに、本
実施例記載の具体的構造のみに基づいて、本発明工法の
構成要件を限定的に解釈することは許されない。[Example] An example of a production line for large-diameter square steel pipes equipped with the method of the present invention and equipment for carrying out the method will be described below with reference to the drawings. Since the specific structural members of the section can be partially modified within the scope of technology known in the art at the time of this application, only the specific structure described in this example can be used without giving any particular reason. Based on this, it is not permissible to interpret the constituent elements of the construction method of the present invention in a limited manner.
【００２１】（その１）図１は、本発明工法を実施する
大径角形鋼管の熱間成形装置の一実施例のラインを示す
概略ブロック図で、図中、材料の搬送方向に沿って直線
的に、１は、コイル装着機構、２は、レベラー、３は、
鋼板幅決め、開先加工部、４は、鋼板のブレークダウン
ロール段、５は、多段式鋼板断面丸めロール機構、６は
、フィンパスロール段、７は、高周波抵抗溶接装置、８
は、溶接ビード内または外削除機構、９は、化石燃料を
熱源とする加熱炉、１０は、高周波加熱炉、１１は、多
段角形断面成形ロール機構、１２は、成形鋼管放冷およ
び冷却部、１３は、鋼管長さ計測機構、１４は、真直成
形部、１５は、走行式カッタ、１６は、矯正装置、１７
は、鋼管定寸切断機である。ただし、コイル巻戻し機構
、ピンチローラ、非常切断機、検査装置等々、図示を省
略した手段も多々ある。(Part 1) FIG. 1 is a schematic block diagram showing the line of an embodiment of a hot forming apparatus for large-diameter square steel pipes that implements the method of the present invention. Specifically, 1 is a coil mounting mechanism, 2 is a leveler, and 3 is a
Steel plate width determination and beveling section; 4, steel plate breakdown roll stage; 5, multi-stage steel plate cross-section rounding roll mechanism; 6, fin pass roll stage; 7, high frequency resistance welding device; 8
9 is a heating furnace using fossil fuel as a heat source; 10 is a high-frequency heating furnace; 11 is a multi-stage rectangular cross-section forming roll mechanism; 12 is a forming steel pipe cooling and cooling section; 13 is a steel pipe length measuring mechanism, 14 is a straight forming section, 15 is a traveling cutter, 16 is a straightening device, 17
is a steel pipe sizing cutting machine. However, there are many means that are not shown, such as a coil rewinding mechanism, a pinch roller, an emergency cutter, an inspection device, etc.
【００２２】上記成形ライン中、コイル装着機構１から
、溶接ビード削除機構８までの装置を通過する鋼材の流
れは、従来、公知のワンシーム電縫丸鋼管製造装置にお
ける、それと略、変りがない。これに使用される鋼板素
材としては、通常、肉厚の熱延コイル（たとえばＳＴＫ
Ｒ４１、５０など）を用いるから、結局、コイル幅が最
終製品（大径角形鋼管）の最大径を制約する（ワンシー
ム管の場合）ことになる。そして、丸鋼管の成形段階で
は、冷間塑性加工により肉厚鋼板（ｔ＝１６〜２６ｍｍ
）を変形するから、その加工工程で上記変形に基づく材
質の加工硬化、残留応力が生じ、また、成形後の高周波
溶接により生じる鋼材の溶接歪を可及的に解消するため
鋼管を長区間にわたって除冷するスペースを設備する。In the above-mentioned forming line, the flow of the steel material passing through the devices from the coil mounting mechanism 1 to the weld bead removing mechanism 8 is substantially the same as that in the conventional one-seam electric resistance welded round steel pipe manufacturing apparatus. The steel plate material used for this is usually a thick hot-rolled coil (for example, STK
R41, 50, etc.), the coil width ultimately limits the maximum diameter of the final product (large diameter square steel pipe) (in the case of a one-seam pipe). In the stage of forming round steel pipes, cold plastic working is performed to form thick steel plates (t = 16 to 26 mm).
), the processing process causes work hardening and residual stress in the material due to the above deformation.In addition, in order to eliminate as much as possible the welding distortion of the steel material caused by high frequency welding after forming, the steel pipe is Provide a space for slow cooling.
【００２３】本発明工法においては、上述、鋼管の除冷
工程に要するスペースを利用し、または、当該スペース
を拡大して、そこに化石燃料を熱源とする搬送方向に対
して比較的に長い加熱炉９と、高周波誘導加熱装置１０
とを設置する。したがって、従来装置に較べ製造ライン
の全長を極端に延長することなく設備することができる
。そこでは、鋼材の高周波溶接加熱部分が冷却しないう
ちに鋼管が加熱装置内に搬送され、順次または、徐々に
、かつ時間をかけて加熱するので鋼材の溶接歪または残
留応力の除去にも効果的であるが、高周波溶接により生
じる鋼材の部分発熱に対して加熱装置内での補正を考慮
する必要があり得る。いずれにしても省エネ効果を期待
することができる。上記の効果は、また、高周波加熱装
置１０を前段に設置し、後側に化石燃料による加熱炉を
設備した場合にも同様である。[0023] In the method of the present invention, the above-mentioned space required for the slow cooling process of the steel pipe is utilized, or the space is expanded, and heating is carried out there using a fossil fuel as a heat source for a relatively long time in the transport direction. Furnace 9 and high frequency induction heating device 10
and set up. Therefore, compared to conventional equipment, the production line can be installed without significantly extending the overall length. In this process, the steel pipe is transported into a heating device before the high-frequency welding heated part of the steel material has cooled down, and is heated sequentially or gradually over time, which is effective in removing welding distortion or residual stress in the steel material. However, it may be necessary to consider correction within the heating device for partial heat generation of the steel material caused by high frequency welding. In either case, energy saving effects can be expected. The above effect is also the same when the high-frequency heating device 10 is installed at the front stage and a heating furnace using fossil fuel is installed at the rear side.
【００２４】図２は、加熱炉９の長手軸直角断面の模式
図を示すもので、図中、１８は、丸鋼管断面、１９は、
炉内に設置した鋼管の両側案内ローラ、２０は、下部案
内兼搬送ローラで、少なくともローラ２０は周面を、つ
づみ形として鋼管１８との接触面積を広く採ることが望
ましい。加熱炉９の内壁は一般に耐火煉瓦を積み重ねて
構築し、天井はアーチ形に形成する。燃焼バーナの配置
、排ガス装置は、図示を省略する。図３は、高周波誘導
加熱装置１０の軸方向直角断面の概念図で、図中、１８
は、丸鋼管断面、２１は、鋼管の周面に沿って設置した
高周波誘導コイルを示す。同コイル２１は、加熱鋼管１
８の周面に近接・対向して設けられるから、鋼管１８に
よっても常時加熱されるのでコイルを銅管によって成形
し、その中に冷却水を循環させて冷却する。FIG. 2 shows a schematic diagram of a cross section perpendicular to the longitudinal axis of the heating furnace 9. In the figure, 18 is a cross section of a round steel pipe, 19 is a cross section of a round steel pipe,
The guide rollers 20 on both sides of the steel pipe installed in the furnace are lower guide/convey rollers, and it is desirable that at least the circumferential surface of the rollers 20 is in the shape of a chain so that the contact area with the steel pipe 18 is wide. The inner wall of the heating furnace 9 is generally constructed by stacking firebricks, and the ceiling is formed in an arch shape. The arrangement of the combustion burner and the exhaust gas device are omitted from illustration. FIG. 3 is a conceptual diagram of a cross section perpendicular to the axial direction of the high-frequency induction heating device 10, in which 18
2 shows a cross section of a round steel pipe, and 21 shows a high-frequency induction coil installed along the circumferential surface of the steel pipe. The coil 21 is connected to the heating steel pipe 1
Since the coil is provided close to and facing the circumferential surface of the coil 8, it is constantly heated by the steel pipe 18, so the coil is formed from a copper pipe and cooling water is circulated therein to cool it.
【００２５】この鋼管１８の加熱レベルを考慮するなら
ば、高周波加熱装置１０は、鋼管加熱工程の前段に設置
することを選択した方が同装置の耐熱・冷却手段に対す
る配慮が比較的に簡単で、高周波コイルまたは装置の保
守、管理あるいは、その耐用期間の延長が容易にできる
メリットが生じる。かくして、加熱工程を経た丸鋼管は
、いずれにしても鋼材のＡ１ またはＡ３ 変態点付近
まで加熱されて、それ迄に施された冷間塑性加工などに
基づく鋼板の残留応力を除去し、材質の改善がなされた
状態のまま直ちに、多段角形成形ロール機構１１内に搬
送され、熱間成形によって断面丸鋼管の周壁を四方から
押圧して、徐々に断面角形の鋼管を成形する。Considering the heating level of the steel pipe 18, it is relatively easier to consider the heat resistance and cooling means of the high-frequency heating device 10 by installing it at the front stage of the steel pipe heating process. This provides the advantage of facilitating maintenance and management of the high-frequency coil or device, as well as extending its service life. In this way, the round steel pipe that has undergone the heating process is heated to around the A1 or A3 transformation point of the steel material, removing the residual stress in the steel plate due to the cold plastic working etc. that has been applied up to that point, and improving the material quality. Immediately, the improved state is transferred to the multi-stage square forming roll mechanism 11, and by hot forming, the circumferential wall of the steel pipe with a round cross section is pressed from all sides to gradually form a steel pipe with a square cross section.
【００２６】多段角形断面成形ロール機構１１の構成段
の、一ローラスタンドの具体例の概略正面図を、図６ま
たは図７に示す。図中、１８’は、やや角形に変形した
鋼管断面、図６においては鋼管長手軸に対し相互に直交
する平行な二軸（成形鋼管の四辺の平面に平行でもある
）に固着された、周面をやや、つづみ形に形成した四個
の成形ロール２２、２２’によって丸鋼管の周面を四方
向、たとえば上、下方向および左右方向から押圧して段
数を経る毎に、徐々に断面角形に近付けるように成形し
ている。かくして成形された鋼管の隅角部のＲの大きさ
は一つのロールスタンド段を通過するたびに縮まり、鋼
管断面は、より正方形に近似し最終製品の断面に近づく
。A schematic front view of a specific example of a one-roller stand, which is one of the constituent stages of the multi-stage rectangular cross-section forming roll mechanism 11, is shown in FIG. 6 or 7. In the figure, 18' is a cross section of a steel pipe that has been deformed into a slightly rectangular shape, and in FIG. The circumferential surface of the round steel pipe is pressed from four directions, for example, from above, below, and from the left and right, using four forming rolls 22, 22' whose surfaces are formed into a slightly interlocking shape. It is shaped to approximate a square shape. The radius of the corner of the thus formed steel pipe decreases each time it passes through one roll stand stage, and the cross section of the steel pipe becomes more square and approaches the cross section of the final product.
【００２７】図７においては、鋼管長手方向軸に直交し
、かつ相互に平行な二軸に固着した周面を深いつづみ形
（逆算盤玉形）の二個の成形ロール２３、２３’によっ
て、丸鋼管の周面を四方向から押圧・成形して、徐々に
断面を角形に近付くようロール形成することができる。
図８は、上記ロール機構によって成形された大径角形鋼
管断面を示すもので、この熱間成形角形鋼管の特徴は、
一見して各隅角部のＲが極めて小さい。鋼管断面で、ハ
ッチを施した部分は前記鋼管を構成する平坦面で、熱処
理を受けて丸鋼管成形時における冷間塑性加工に基づく
材質の加工硬化の解消、残留応力および高周波溶接歪の
除去が行われた部分であり、それ以外の隅角部は、熱間
加工によって塑性変形を受けた部分であって、全体とし
て残留応力は極めて少なく、また、材質の劣化も認めら
れない。In FIG. 7, the circumferential surface fixed to two axes perpendicular to the longitudinal axis of the steel pipe and parallel to each other is formed by two forming rolls 23 and 23' in the shape of a deep chain (counterboard ball shape). By pressing and forming the peripheral surface of a round steel pipe from four directions, it is possible to roll it so that the cross section gradually approaches a rectangular shape. FIG. 8 shows a cross section of a large-diameter square steel pipe formed by the roll mechanism, and the characteristics of this hot-formed square steel pipe are as follows:
At first glance, the radius of each corner is extremely small. In the cross section of the steel pipe, the hatched part is the flat surface that constitutes the steel pipe, which is heat treated to eliminate the work hardening of the material due to cold plastic working during the forming of the round steel pipe, and to eliminate residual stress and high-frequency welding distortion. The other corner parts are the parts that have undergone plastic deformation due to hot working, and the residual stress as a whole is extremely small, and no deterioration of the material is observed.
【００２８】上述工法によれば、
（イ）丸鋼管を断面角形に成形する際、従来工程では丸
鋼管を一旦サイザーを通して断面を真円にしてからでな
いと、正確な角形鋼管が得られなかったが、本発明工法
では、熱間加工で鋼材が軟化し容易に変形するため、丸
鋼管をサイザーに掛けることなく精度の高い加工を行う
ことができる。
（ロ）丸鋼管を断面角形に成形するとき、丸鋼管の周壁
温度を、略、均一にして置かないと正確な角形鋼管が得
られないが、本発明工法によれば鋼管全体を鋼材のＡ１
またはＡ３ 変態点付近まで加熱するので変形し易く
、高精度寸法の角形鋼管を成形することができる。According to the above-mentioned method, (a) When forming a round steel pipe into a square cross section, in the conventional process, the round steel pipe had to be passed through a sizer to make the cross section a perfect circle, in order to obtain an accurate square steel pipe. However, in the method of the present invention, since the steel material softens during hot working and easily deforms, highly accurate processing can be performed without hanging the round steel pipe on a sizer. (b) When forming a round steel pipe into a square cross section, an accurate square steel pipe cannot be obtained unless the temperature of the circumferential wall of the round steel pipe is kept approximately uniform; however, according to the method of the present invention, the entire steel pipe is made of A1 steel material.
Or A3: Since it is heated to near the transformation point, it is easily deformed and a rectangular steel pipe with highly accurate dimensions can be formed.
【００２９】（ハ）熱間加工であるため、角形鋼管の隅
角部のＲを極めて小さく形成でき、角形鋼管の断面係数
を大きくすることができる上に、加工による残留応力が
小さく隅角部付近の材質の劣化が生じ難い。
（ニ）熱間加工であるため、成形ロール機構の駆動エネ
ルギーが、冷間加工に較べて大幅に少ない。
（ホ）成形加工が容易であって鋼板の変形に無理が掛か
らないから、角形鋼管成形加工に基づく鋼管の捩れが生
じないか、殆んど生じない。
（ヘ）角形鋼管成形後、加熱温度が高い間に、四方から
均等に冷風を吹き掛けるとか冷水を噴霧して急速に冷却
し、前工程における鋼材の焼きなましによる鋼管材質の
軟化傾向を、焼入れにより回復することができる。ただ
し、焼入れに基づく鋼管の歪の発生状態に注意を要する
。
（ト）角形鋼管成形後における鋼材の冷却に要するスペ
ースを短かく設定することができる。(c) Because hot working is used, the corner radius of the square steel pipe can be formed to be extremely small, the section modulus of the square steel pipe can be increased, and the residual stress due to processing is small, making the corner part Deterioration of nearby materials is less likely to occur. (d) Since it is hot working, the driving energy of the forming roll mechanism is significantly less than that in cold working. (E) Since the forming process is easy and no strain is applied to the deformation of the steel plate, twisting of the steel pipe due to the forming process of the square steel pipe does not occur or almost never occurs. (f) After forming a square steel pipe, while the heating temperature is high, cool it rapidly by blowing cold air evenly from all sides or spraying cold water, and by quenching, the tendency of the steel pipe material to soften due to the annealing of the steel material in the previous process can be recovered. However, it is necessary to pay attention to the state in which distortion occurs in steel pipes due to quenching. (g) The space required for cooling the steel material after forming the square steel pipe can be set short.
【００３０】（その２）鋼材の冷間塑性加工などに基づ
いて生じる残留応力とか材質の劣化を除去・修復するた
めには鋼板の熱処理温度を高めに、処理時間を長めに設
定することが望ましいが、それでは鋼管表面の肌荒れが
生じ最終製品の商品価値が下るし、これを除去するのに
ショットピーニング、サンドブラスト処理などが必要に
なってコストアップの条件を増す。かつ、鋼材の熱処理
に要する費用、工賃も無視できない量になる。また、熱
処理温度を低めに設定すれば鋼板の肌荒れは防止できる
が、角形鋼管の各隅角部付近の材質の焼きなましが、不
充分になるおそれがある。そこで本発明第２工法では、
角形鋼管材で特に問題視されている各隅角部付近の鋼材
の冷間加工に基づく劣化を回復できるように、丸鋼管周
壁の隅角部予定個所付近の局部加熱加工を採用している
。(Part 2) In order to remove and repair residual stress and material deterioration that occur due to cold plastic working of steel materials, it is desirable to set the heat treatment temperature of the steel plate to be high and the treatment time to be long. However, this causes roughness on the surface of the steel pipe, lowering the commercial value of the final product, and requires shot peening, sandblasting, etc. to remove this, which increases the cost. Moreover, the costs and labor costs required for heat treatment of steel materials are also non-negligible. Further, if the heat treatment temperature is set to a low value, roughening of the surface of the steel plate can be prevented, but there is a risk that the material near each corner of the square steel pipe may not be sufficiently annealed. Therefore, in the second method of the present invention,
In order to recover from the deterioration caused by cold working of the steel near each corner, which is a particular problem with square steel pipes, local heating is applied near the planned corners of the circumferential wall of the round steel pipe.
【００３１】しかしながら、鋼管周壁の加熱温度が不均
一で、その間に極端な差異が生じるときは、これを図６
ないし図７に示すような角形断面成形ロール機構に搬入
しても、良好な角形断面が得られないことが知られてい
る。このため本実施例装置では、丸鋼管周壁に対し局部
加熱を施すと共に、丸鋼管全体を、たとえば鋼材のＡ１
変態点付近まで均一に加熱して、両部材の材質の軟化
度合を調整し、かつ、これによって角形鋼管周壁を構成
する平坦面材質の加工硬化、残留応力を除去する熱処理
を行う。上記丸鋼管の均一熱処理は、本発明実施例（そ
の１）に説明した、図１記載のような装置を利用して行
うことができる。ただし、ここでは、鋼材のＡ３ 変態
点まで熱処理温度を上げる必要がないから、熱処理装置
が占めるスペースは比較的小さくて済む。However, if the heating temperature of the peripheral wall of the steel pipe is non-uniform and there is an extreme difference between them, this can be
It is known that a good square cross section cannot be obtained even if the material is introduced into a square cross section forming roll mechanism as shown in FIG. Therefore, in the present embodiment, the peripheral wall of the round steel pipe is locally heated, and the entire round steel pipe is heated, for example, with the A1
Heat treatment is performed to adjust the degree of softening of the materials of both members by uniformly heating to near the transformation point, and thereby work harden the flat surface material that makes up the peripheral wall of the square steel pipe and remove residual stress. The uniform heat treatment of the round steel pipe can be performed using the apparatus shown in FIG. 1, which was explained in the embodiment (part 1) of the present invention. However, here, since there is no need to raise the heat treatment temperature to the A3 transformation point of the steel material, the space occupied by the heat treatment apparatus can be relatively small.
【００３２】図４および図５は、丸鋼管周壁の隅角部予
定個所付近の局部加熱装置の一実施例の模式図を示すも
ので、この場合は、いずれも電気エネルギーを利用する
高周波加熱コイル２４、２４’を各一対、鋼管１８の長
手方向中心軸の直角断面内で、前記軸に対し、対称に、
かつ相互に９０゜位相をずらして設置する。コイル２４
、の対、コイル２４’の対は、鋼管長手軸方向に相互に
若干ずらして設置しても可である。図において、鋼管断
面周壁材に、それぞれハッチが施されている個所が局部
加熱によって特に温度上昇した部分を示すもので、図５
の場合は、鋼管材の内側をより加熱できるよう、コイル
２４’に印加する周波数などを調整し、角形鋼管成形時
に各隅角部の変形を、より自由に、無理なく行うことが
できるようにし、隅角部Ｒが、よりシャープな形状の角
形鋼管を得るようしたものである。FIGS. 4 and 5 are schematic diagrams of an embodiment of a local heating device near a planned corner of a peripheral wall of a round steel pipe. 24, 24' in a cross section perpendicular to the longitudinal central axis of the steel pipe 18, symmetrically with respect to said axis,
They are also installed with a phase shift of 90° from each other. coil 24
, and the pair of coils 24' may be installed slightly offset from each other in the longitudinal axis direction of the steel pipe. In the figure, hatched areas on the steel pipe cross-sectional surrounding wall material indicate areas where the temperature has particularly increased due to local heating, and Figure 5
In this case, the frequency applied to the coil 24' should be adjusted so that the inside of the steel pipe material can be heated more, so that each corner can be deformed more freely and effortlessly when forming a square steel pipe. , a square steel pipe with a sharper corner R is obtained.
【００３３】この鋼管周壁の局部加熱の熱源は勿論、化
石燃料を利用したバーナであって良い。全体加熱および
局部加熱が終った丸鋼管は、その加熱状態を保持したま
ま、図１に示す多段角形断面成形ロール機構１１内に搬
送され、同機構内で、たとえば図６または図７に示すよ
うな成形ロールの複数段を通過して徐々に成形され、図
８に示すような高品質の大径角形鋼管が形成される。そ
の後の工程は、実施例（その１）に述べたところと変り
がない。The heat source for local heating of the peripheral wall of the steel pipe may of course be a burner using fossil fuel. The round steel pipe that has been completely heated and locally heated is transported, while maintaining its heated state, into the multi-stage rectangular cross-section forming roll mechanism 11 shown in FIG. The material is gradually formed by passing through multiple stages of forming rolls to form a high-quality large-diameter rectangular steel pipe as shown in FIG. The subsequent steps are the same as those described in Example (Part 1).
【００３４】上記工法によれば、
（イ）丸鋼管を鋼材のＡ３ 変態点付近まで加熱、熱処
理を施したと略、同等な角形鋼管材質に対する効果を期
待することができる割に熱処理設備を小型化することが
できる上に、燃料および／または電力の消費量を節減す
ることができる。
（ロ）その他、本実施例工法によって奏する効用は、実
施例（その１）記載の、それと略、同一である。According to the above method, (a) the round steel pipe is heated and heat-treated to near the A3 transformation point of the steel material, and the heat treatment equipment is small compared to the same effect that can be expected for square steel pipe materials. In addition, fuel and/or power consumption can be reduced. (b) Other effects achieved by the construction method of this example are substantially the same as those described in Example (Part 1).
【００３５】[0035]
【発明の効果】以上のとおりであって、本発明工法によ
れば、冷間塑性加工により製造されている従来公知の大
径角形鋼管において問題視されていた鋼管の各隅角部材
質の劣化を回復して、その残留応力を除去し許容量以下
にすると共に、平坦部材の加工硬化、内部応力を焼きな
ましにより除去して全体的に品質の安定した大径角形鋼
管を得ることができると共に、材質劣化を伴なうことな
く可及的にシャープな隅角部を成形して高品質な鋼管を
提供できる。[Effects of the Invention] As described above, according to the method of the present invention, the material of each corner of the steel pipe deteriorates, which has been considered a problem in conventional large diameter square steel pipes manufactured by cold plastic working. It is possible to recover the residual stress and reduce it to below the allowable level, work harden the flat member, and remove the internal stress by annealing to obtain a large diameter rectangular steel pipe with overall stable quality. It is possible to provide high-quality steel pipes by forming corners as sharp as possible without causing material deterioration.
【００３６】角形鋼管の成形工程における鋼管の熱処理
操作について、■鋼管の全体的加熱の場合には角形鋼管
の成形が容易でシャープな隅角部を形成し、高品質な大
径角形鋼管を提供する。■品質が均一で、かつ、安定し
た鋼管が得られる。■鋼管の部分加熱（といっても全体
的に鋼管低温加熱をする）の場合には、奏し得る作用、
効果に比較して加熱エネルギーを節減することができる
。■比較的に熱処理設備が占めるスペースが小さい。
■熱処理操作に要するコストを比較的安価にまとめ得る
。Regarding the heat treatment operation of the steel pipe in the process of forming the square steel pipe, ■ In the case of heating the entire steel pipe, the square steel pipe can be easily formed, forming sharp corners, and providing a high-quality large-diameter square steel pipe. do. ■Produces steel pipes with uniform quality and stability. ■In the case of partial heating of steel pipes (although the entire steel pipe is heated at low temperature), the effects that can be achieved,
Compared to the effect, heating energy can be saved. ■The space occupied by heat treatment equipment is relatively small. ■The cost required for heat treatment operations can be reduced to a relatively low cost.
【００３７】熱処理設備の加熱源として、電力を利用す
る場合は、
（イ）被加熱物を所要温度まで加熱するのに必要な設備
の占めるスペースが狭くてすむ。
（ロ）被加熱物の温度管理が容易、
（ハ）品質の安定したものが得られる。
（ニ）設備のメンテナンスに手が掛からない。
（ホ）デメリットとしては、電力コストが高い。
（ヘ）立地条件によっては、社会共通資本が整備されて
おらず、所望量の大電力の供給が受けられない場合もあ
り得る。
すなわち、立地条件が制約される。When electric power is used as a heating source for heat treatment equipment, (a) the space occupied by the equipment necessary to heat the object to the required temperature can be reduced; (b) It is easy to control the temperature of the heated object, and (c) products of stable quality can be obtained. (d) Equipment maintenance is not required. (e) The disadvantage is the high electricity cost. (f) Depending on the location, social common capital may not be in place and it may not be possible to receive the desired amount of large-scale electricity supply. In other words, location conditions are restricted.
【００３８】化石燃料を熱源として利用する場合は、■
熱処理のコストが安い。■大量入手、運搬が立地条件に
より左右されず比較的に容易である。■必要に応じて大
容量消費設備の構築が可能、■デメリットとしては、加
熱設備の占めるスペースが大である。熱処理設備をイン
ラインでつなぐと、それに起因して鋼管成形のラインの
長さが大幅に伸長するから、設備立地の選択の幅が狭ま
る。■所要加熱温度の制御が若干むずかしい。■メンテ
ナンスに人手を要する。上述の電力、化石燃料利用のメ
リット、デメリットを綜合勘案し、電力・化石燃料によ
る複合加熱手段を採用すれば、従来公知の加熱炉と比較
して相互のデメリットを補完した高性能な熱処理設備を
設置することができる。等々、公知の工法には期待する
ことができない、格別の作用、効果を奏するものとなる
。[0038] When using fossil fuel as a heat source,
The cost of heat treatment is low. ■It is relatively easy to obtain and transport in large quantities, regardless of location conditions. ■It is possible to construct large-capacity consumption equipment as needed; ■The disadvantage is that the heating equipment takes up a large amount of space. If heat treatment equipment is connected in-line, the length of the steel pipe forming line will be significantly extended, which will narrow the range of equipment location options. ■It is somewhat difficult to control the required heating temperature. ■Manpower is required for maintenance. By comprehensively taking into account the advantages and disadvantages of using electricity and fossil fuels, and adopting a combined heating method using electricity and fossil fuels, it is possible to create high-performance heat treatment equipment that compensates for the disadvantages of both, compared to conventional heating furnaces. can be installed. These and other special functions and effects cannot be expected from known construction methods.
【図１】本発明工法を実施する大径角形鋼管の熱間成形
装置の一実施例のブロック図、FIG. 1 is a block diagram of an embodiment of a hot forming apparatus for large-diameter square steel pipes that implements the method of the present invention;
【図２】熱処理設備に使用される化石燃料を熱源とする
加熱炉の断面図、[Figure 2] Cross-sectional view of a heating furnace using fossil fuel as a heat source used in heat treatment equipment,
【図３】鋼管全体を加熱する高周波加熱装置のコイル部
分図、[Figure 3] Partial diagram of the coil of the high-frequency heating device that heats the entire steel pipe,
【図４】鋼管周壁の部分加熱装置、[Figure 4] Partial heating device for steel pipe peripheral wall,
【図５】鋼管周壁の部分加熱装置（別の実施例）、[Fig. 5] Partial heating device for steel pipe peripheral wall (another embodiment),
【図
６】鋼管断面の角形成形ローラ（部分）、[Figure 6] Square forming roller (part) of steel pipe cross section,
【図７】鋼管
断面の角形成形ローラ（別の実施例）、[Fig. 7] Angular forming roller of steel pipe cross section (another embodiment),
【図８】本発明
工法により成形された大径角形鋼管断面図。FIG. 8 is a cross-sectional view of a large-diameter square steel pipe formed by the method of the present invention.
１ 熱延コイル装着機構 ２ レベラー ３ 鋼板幅決め・開先加工部 ４ ブレークダウンローラ ５ 多段式鋼板断面丸めロール機構 ６ フィンパスロール ７ 高周波溶接装置 ８ 溶接ビード削除機構 ９ 化石燃料を熱源とする加熱炉 １０ 高周波加熱炉 １１ 多段角形断面成形ロール機構 １２ 成形鋼管放冷および冷却部 １３ 計測機構 １４ 真直成形部 １５ 走行式カッタ １６ 矯正装置 １７ 鋼管定寸切断機 １８ 丸鋼管 1 Hot rolled coil mounting mechanism 2 Leveler 3 Steel plate width determination/bevel processing section 4 Breakdown roller 5. Multi-stage steel plate cross-section rounding roll mechanism 6 Fin Pass Roll 7 High frequency welding equipment 8 Weld bead removal mechanism 9 Heating furnace that uses fossil fuel as a heat source 10 High frequency heating furnace 11 Multi-stage square cross-section forming roll mechanism 12 Molded steel pipe cooling and cooling section 13 Measurement mechanism 14 Straight forming part 15 Traveling cutter 16 Correction device 17 Steel pipe sizing cutting machine 18 Round steel pipe
Claims (2)
形し、その両側縁を突合わせ溶接して形成した連続丸鋼
管の外周全体を、ガス、油等の化石燃料を熱源とした加
熱と電気エネルギーによる高周波加熱とにより複合加熱
して丸鋼管全体を均等な所要温度に維持するよう温度管
理しながら、前記鋼管を角形成形用ロールスタンドに移
送することを特徴とする大径角形鋼管の熱間成形工法。Claim 1: The entire outer periphery of a continuous round steel pipe, which is formed by forming a strip steel plate into a round shape with a cross section perpendicular to the longitudinal direction and butt welding its both side edges, is heated using a fossil fuel such as gas or oil as a heat source. A large-diameter square steel pipe characterized in that the steel pipe is transferred to a roll stand for square forming while temperature-controlled to maintain the entire round steel pipe at a uniform required temperature through composite heating by high-frequency heating using electric energy. Hot forming method.
形し、その両側縁を突合わせ溶接して形成した連続丸鋼
管の外周全体を、ガス、油等の化石燃料熱源または電気
エネルギーによる高周波加熱装置により、あるいは前記
両加熱手段の複合加熱により加熱すると共に、コーナー
予定個所付近のみを高周波加熱装置または化石燃料を利
用したバーナ等による部分加熱を施すと共に、前記鋼管
を角形成形用ロールスタンドに移送することを特徴とす
る大径角形鋼管の熱間成形工法。[Claim 2] The entire outer periphery of a continuous round steel pipe, which is formed by forming a strip steel plate into a round shape with a cross section perpendicular to the longitudinal direction and butt-welding both side edges thereof, is heated by a fossil fuel heat source such as gas or oil, or by electric energy. The steel pipe is heated by a high-frequency heating device or by combined heating of both of the above-mentioned heating means, and partial heating is applied only to the vicinity of the planned corner by a high-frequency heating device or a burner using fossil fuel, and the steel pipe is placed on a roll stand for corner forming. A hot forming method for large diameter square steel pipes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13855791A JP2735402B2 (en) | 1991-05-15 | 1991-05-15 | Hot forming method for large diameter square steel pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13855791A JP2735402B2 (en) | 1991-05-15 | 1991-05-15 | Hot forming method for large diameter square steel pipe |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04339517A true JPH04339517A (en) | 1992-11-26 |
| JP2735402B2 JP2735402B2 (en) | 1998-04-02 |
Family
ID=15224930
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13855791A Expired - Lifetime JP2735402B2 (en) | 1991-05-15 | 1991-05-15 | Hot forming method for large diameter square steel pipe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2735402B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10263626A (en) * | 1997-03-24 | 1998-10-06 | Kawasaki Steel Corp | Seamless square steel pipe and production thereof |
| JP2009090363A (en) * | 2007-10-12 | 2009-04-30 | Jfe Steel Kk | Equipment and method for manufacturing square steel tube |
| KR101045839B1 (en) * | 2008-10-02 | 2011-07-01 | 주식회사 엠에스 오토텍 | Furnace Equipment for Hot Stamping |
-
1991
- 1991-05-15 JP JP13855791A patent/JP2735402B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10263626A (en) * | 1997-03-24 | 1998-10-06 | Kawasaki Steel Corp | Seamless square steel pipe and production thereof |
| JP2009090363A (en) * | 2007-10-12 | 2009-04-30 | Jfe Steel Kk | Equipment and method for manufacturing square steel tube |
| KR101045839B1 (en) * | 2008-10-02 | 2011-07-01 | 주식회사 엠에스 오토텍 | Furnace Equipment for Hot Stamping |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2735402B2 (en) | 1998-04-02 |
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