JP2000000605A - Seamless tube and its manufacture - Google Patents

Seamless tube and its manufacture

Info

Publication number
JP2000000605A
JP2000000605A JP16681598A JP16681598A JP2000000605A JP 2000000605 A JP2000000605 A JP 2000000605A JP 16681598 A JP16681598 A JP 16681598A JP 16681598 A JP16681598 A JP 16681598A JP 2000000605 A JP2000000605 A JP 2000000605A
Authority
JP
Japan
Prior art keywords
piercing
plug
back pressure
round
cast
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.)
Pending
Application number
JP16681598A
Other languages
Japanese (ja)
Inventor
Tatsuro Katsumura
龍郎 勝村
Takashi Ariizumi
孝 有泉
Tatsuharu Oda
龍晴 小田
Yoshihide Okamoto
芳秀 岡本
Masahiko Yasukawa
雅彦 安川
Tsutomu Sugiyama
努 杉山
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Engineering Corp
Original Assignee
NKK Corp
Nippon Kokan Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by NKK Corp, Nippon Kokan Ltd filed Critical NKK Corp
Priority to JP16681598A priority Critical patent/JP2000000605A/en
Publication of JP2000000605A publication Critical patent/JP2000000605A/en
Pending legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To manufacture a pipe without causing cost increase even for a hardly workable material or the like and without remaining a flaw on the pipe inner face by obliquely piercing and rolling a round cast metal as casting by using a plug and pressing/piercing a base stock as required, by imparting a back pressure to the base stock through a pusher. SOLUTION: A base stock billet 1 made of a round cast metal as casting, while being bitten with a piercing roll 2, is pierced by pushing a piercing plug 3. In this obliquely piercing and rolling, in the case that the biting of the base stock billet 1 is insufficient due to the reaction force of the plug 3, while imparting a back pressure to the stock 1 with a pusher 4, the piercing is conducted until the billet 1 is stably bitten. In particular, in the case that a round cast metal of the stock is a hardly workable material, this method can produce a seamless tube not having a flaw on the inner face by using conventional equipment. An alloy steel which contains >=0.5% Cr, >=1% Cr+Ni+Mo and further as required, >=0.001% S and in which porosity or the like is apt to cause in the center part of the cast metal, is used as the hardly workable material.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】本発明は、従来熱間加工性が
劣悪で継目無管材として不適当であった難加工材または
鋳造ままであるため素材中心部にザク等が存在する品質
の悪い素材を穿孔するに際し、疵の発生を抑止できる技
術に関するものである。
BACKGROUND OF THE INVENTION The present invention relates to a difficult-to-work material which has been poor in hot workability and is unsuitable as a seamless pipe material, or a poor-quality material in which zaku or the like is present at the center of the material because it is cast. The present invention relates to a technique capable of suppressing the occurrence of flaws when drilling holes.

【0002】[0002]

【従来の技術】継目無管は一般に鋳造した鋳片に加工を
加えて、あるいは連続鋳造により作られた丸または角鋼
片状のビレットを用い、マンネスマン穿孔あるいはプレ
ス穿孔、または熱間押出し等により中空素管にされ、そ
の後エロンゲータ、プラグミルまたはマンドレルミル等
の圧延機により延伸され、最終的にサイザーやストレッ
チレデューサにより定径される工程を経て製品となる。
2. Description of the Related Art A seamless pipe is generally manufactured by working a cast slab, or using a round or square billet-shaped billet made by continuous casting, and by means of Mannesmann drilling or press drilling, or hot extrusion. It is made into a base tube, then drawn by a rolling machine such as an elongator, a plug mill or a mandrel mill, and finally passed through a step of sizing by a sizer or a stretch reducer to obtain a product.

【0003】継目無管の素材には、合金成分の少ない一
般の低炭素鋼のように丸型鋼片への連続鋳造が比較的容
易の行え、素材の熱間加工性が良いものは鋳造まま、鋳
造ままでは鋼片中央部にポロシティや偏析が生じやすい
ステンレス鋼など、熱間加工性の悪いものであれば大き
な加工を加え丸型鋼片とするものがある。
[0003] For a seamless tube material, continuous casting to a round billet can be performed relatively easily, such as a general low carbon steel having a small alloying component, and a material having a good hot workability is cast as it is. If the hot workability is poor, such as stainless steel, which tends to cause porosity and segregation in the center of the slab as cast, there is a round slab that is subjected to large processing.

【0004】加工性劣化の主とした理由は連鋳鋳片の中
心部偏析やポロシティであり、特に大きな影響を与える
ポロシティの発生機構は一般に、鋳片の最終凝固段階に
おいて空隙が生じ、本来なら溶鋼が供給されるべきとこ
ろが、高合金鋼などの場合ではCr等の含有量が高いた
めに溶鋼の粘性が上昇するなどの理由で溶鋼が供給され
ないことに起因する。例えばCr量では、図3に示すよ
うに、0.5%を超えると溶鋼の粘性が急激に増加し、
このため、ポロシティが生じやすくなる。このように内
部欠陥を内包する可能性のある素材を鋳造ままで用いた
場合は、製管工程の最初にマンネスマン穿孔という過酷
な加工を受けるため、軸芯部のポロシティや偏析により
管内面疵が発生する。
[0004] The main reason for the deterioration of workability is segregation and porosity in the center of a continuous cast slab. The porosity generating mechanism which has a particularly large influence is generally caused by voids in the final solidification stage of the cast slab. The reason why molten steel is to be supplied is that high-alloy steel or the like does not supply molten steel because the content of Cr or the like is high and the viscosity of the molten steel increases. For example, as shown in FIG. 3, when the amount of Cr exceeds 0.5%, the viscosity of molten steel sharply increases,
Therefore, porosity is likely to occur. If a material that may contain internal defects is used as cast in this way, it undergoes severe processing called Mannesmann drilling at the beginning of the pipe making process, and the inner surface flaw of the pipe due to porosity and segregation of the shaft core part appear.

【0005】このため、特に難加工性材料等と呼ばれ
る、合金成分を多く含有する鋼や加工性を劣化させる硫
黄Sを比較的多く含有する快削鋼などの炭素鋼はもとよ
り、炭素量の多い普通鋼種やCrが添加された鋼種につ
いても内部品質を向上させるための穿孔圧延が必要であ
るといわれていた。例えば、高Cr鋼の継目無管素材の
製造方法として、400×520mmの比較的大断面を持
つ角形状のブルームを連続鋳造機等により鋳造し、加熱
後、分塊圧延等を用いて矩形型鋼塊から小断面の丸型鋼
塊、すなわち丸ビレットを製造するといった要領であ
る。
[0005] For this reason, carbon steels such as steels containing a large amount of alloy components and free-cutting steels containing a relatively large amount of sulfur S, which deteriorates the workability, which are particularly called difficult-to-work materials, have a large carbon content. It has been said that piercing and rolling for improving the internal quality is also required for ordinary steel types and steel types to which Cr is added. For example, as a method for producing a seamless pipe material of high Cr steel, a rectangular bloom having a relatively large cross section of 400 × 520 mm is cast by a continuous casting machine or the like, heated, and then subjected to a slab rolling or the like to obtain a rectangular steel. The method is to manufacture a round steel ingot of small cross section, that is, a round billet from the ingot.

【0006】このような鋳造材に予加工を加え継目無管
素材とする製造は、鋳造ままで素材となすことのできる
鋼種と比べ、工程の増加、予加工時の加熱などによるコ
ストの増加につながるため、できる限り予加工を加えず
に製管する手法が求められていた。この問題を解決する
ために、一つは鋳造方法の改善、また一つは製管方法の
改善が多く提案されている。
[0006] The production of such a cast material as a seamless pipe material by pre-processing is an increase in costs due to an increase in the number of steps and heating during pre-processing, as compared with a steel type that can be used as a material as cast. In order to be connected, there was a need for a method of producing pipes without adding pre-processing as much as possible. In order to solve this problem, many proposals have been made, one being an improvement in the casting method and the other being an improvement in the pipe making method.

【0007】鋳造方法の改善については、連続鋳造材を
鋳造中に圧下し、欠陥を機械的に圧着させる、いわゆる
軽圧下プロセスがスラブなど、矩形断面の鋼片において
はよく適用される。この軽圧下プロセスを丸ビレットに
適用したときの大きな問題は、圧下ロールにより引き起
こされる鋳片形状の悪化と圧下を増加したときに発生す
る可能性のある凝固界面の割れである。単純に丸鋳片を
一対の平ロールにより圧下すれば、当然圧下部はつぶ
れ、断面は扁平化する。しかも圧下により、断面内で圧
下方向と直交する方向に引張り応力が発生することで割
れが生じやすくなる。また、ポロシティの圧着効果を高
めるために圧下量を大きくすれば、形状はさらに真円か
ら遠ざかり、割れの発生率は高くなり、継目無管製造用
の丸ビレットとして用いるには、ビレットを転がすこと
によって行う搬送ができなくなり、また穿孔時の噛込み
が不安定になる等の重大な問題が発生し、結局、鋳片の
内部品質が不十分なままで我慢せざるを得ない。
With respect to the improvement of the casting method, a so-called light reduction process in which a continuous cast material is reduced during casting to mechanically compress a defect is often applied to a steel piece having a rectangular cross section such as a slab. The major problems when applying this light reduction process to round billets are the deterioration of the slab shape caused by the reduction roll and the cracks at the solidification interface that can occur when increasing the reduction. If the round slab is simply rolled down by a pair of flat rolls, the rolled-down portion is naturally collapsed and the cross section becomes flattened. In addition, the rolling tends to cause a crack due to the generation of a tensile stress in a direction perpendicular to the rolling direction in the cross section. Also, if the rolling amount is increased to increase the porosity's crimping effect, the shape goes further away from a perfect circle, the cracking rate increases, and the billet must be rolled to be used as a round billet for seamless pipe production As a result, serious problems such as inability to carry out and instability in biting at the time of perforation occur, and as a result, the internal quality of the slab has to be put up with insufficient.

【0008】この問題を解決するため、例えば特開平7
−108358号公報(以下先行技術1)に記載のよう
に、圧下される部分を予め大きめにしておくという楕円
モールドによる鋳造法も提案されている。この方法は軽
圧下に対しては有効であるものの、真円モールドに比べ
鋳造時の流れが不均一になることに起因する湯面変動や
パウダーの引き込みにより、新たな欠陥の原因になるこ
とが明らかであり、完全な解決策にはなり得ない。
To solve this problem, for example, Japanese Patent Application Laid-Open
As described in JP-A-108358 (hereinafter referred to as Prior Art 1), a casting method using an elliptical mold in which a portion to be reduced is enlarged in advance has been proposed. Although this method is effective under light pressure, it can cause new defects due to fluctuations in the molten metal surface and powder pull-in caused by uneven flow during casting compared to a perfect circular mold. It is obvious and cannot be a complete solution.

【0009】一方、製管プロセスにおいても、穿孔時の
マンネスマン割れに起因する内面疵発生防止技術を検討
した事例は多い。例えば、特開昭55−106611号
公報(以下先行技術2)では内面疵の発生限界のみなら
ず、噛込みや偏肉についても穿孔条件を規定できるとの
提案がなされている。ところが、先行技術2中にも記載
されているように、内面疵の発生限界は素材の材質、温
度、製法に依存するために、連続鋳造ままの素材や難加
工材と呼ばれるものについては、この先行技術を適用し
ても疵の発生を防止できない。
On the other hand, in the pipe making process, there have been many cases in which a technique for preventing the occurrence of inner surface flaws caused by Mannesmann cracking during drilling has been studied. For example, Japanese Unexamined Patent Publication No. 55-106611 (hereinafter referred to as Prior Art 2) proposes that not only the generation limit of the inner surface flaw but also the perforation conditions can be defined not only for the bite or uneven thickness. However, as described in Prior Art 2, since the generation limit of the inner surface flaw depends on the material, temperature, and manufacturing method of the material, the material as it is continuously cast and what is called a difficult-to-work material is used. Even if the prior art is applied, generation of flaws cannot be prevented.

【0010】また、穿孔ロールの傾斜角を噛込み前から
その直後まで、および尻抜け直前と直後、これらと定常
圧延中との水準を変化させることで内面疵の発生を抑制
するという技術が特許第1811008号(以下先行技
術3)に記載されている。この先行技術3は疵抑制とい
う観点では、理にかなった方法を適用している。すなわ
ち、マンネスマン割れを抑制する手段として、ロール傾
斜角の高い状態で穿孔を継続したい、ところが、その場
合は噛込み不良が生じやすくなるために、噛込み、尻抜
け時のみ傾斜角を小さくするというものである。しかし
ながら、この技術も万能とは言い難い。この技術によれ
ば、素材材質が劣悪である場合には、かなりの低傾斜角
で噛込ませ、その直後に能率を維持するために高傾斜角
にロールを配置せねばならず、かなりの機械的負荷が発
生する。このため故障の危険があり、本来の目的である
生産能率の向上には必ずしも寄与できない。しかも、疵
そのものは低傾斜角で噛込ませる間にも生じているか
ら、噛込み時と尻抜け時、すなわち管の先後端に生じる
疵は抑制できない。然るに生産能率を維持しつつ、内面
品質の良い製品を作ることは困難である。また、大きな
機械的負荷に耐えられるように設計する必要があるので
設備費も高価なものとなる。
[0010] Further, a technique is disclosed in which the angle of inclination of the perforating roll is changed from before to immediately after biting, and immediately before and after the trailing edge, and between these levels and during steady rolling to suppress the occurrence of internal flaws. No. 1811008 (hereinafter referred to as Prior Art 3). This prior art 3 applies a reasonable method from the viewpoint of suppressing flaws. In other words, as means for suppressing Mannesmann cracking, it is desired to continue punching in a state where the roll inclination angle is high. However, in this case, it is easy to cause biting failure. Things. However, this technology is not universal. According to this technology, when the material is inferior, the roll must be arranged at a high inclination angle in order to maintain the efficiency immediately after being engaged at a considerably low inclination angle, and a considerable machine is required. Load occurs. For this reason, there is a risk of failure, and it cannot always contribute to the improvement of the production efficiency, which is the original purpose. In addition, since the flaw itself is also generated during the biting at a low inclination angle, the flaw generated at the time of biting and at the end of the buttocks, that is, at the front and rear ends of the pipe cannot be suppressed. However, it is difficult to produce products with good internal quality while maintaining production efficiency. In addition, equipment must be designed to withstand a large mechanical load, so that equipment costs are high.

【0011】一方、素材の加工性が劣悪である場合に、
その製造方法を検討した例も多くある。例えば特許第1
828639号(以下先行技術4)では、硫黄快削鋼、
鉛快削鋼等の快削鋼製継目無管をマンネスマン製管法に
て製造するにあたり、素材先端外径をロール開度以下に
すべくテーパ加工し、内面疵を抑制する技術が開示され
ている。この先行技術は特開昭56−89307号公報
等の先行技術を引き合いに出し、素材の加工や製管後の
手入れが多くなるために問題であるとしているが、この
先行技術も素材端面にテーパ加工を施すという点でその
枠を超えるものではなく、製造コストを低減できる技術
ではない。
On the other hand, when the workability of the material is poor,
There are many examples of studying the manufacturing method. For example, Patent No. 1
No. 828639 (hereinafter referred to as Prior Art 4) discloses a sulfur free-cutting steel,
In manufacturing a seamless pipe made of free-cutting steel such as lead free-cutting steel by the Mannesmann pipe manufacturing method, a technique has been disclosed in which taper processing is performed so that the outer diameter of the material tip is equal to or less than the roll opening degree, and inner surface flaws are suppressed. I have. This prior art refers to a prior art such as Japanese Patent Application Laid-Open No. 56-89307, which is considered to be a problem because the processing of the material and the maintenance after pipe production increase, but this prior art also has a taper on the end face of the material. It does not exceed the limit in terms of processing, and is not a technology that can reduce manufacturing costs.

【0012】また、製造コストを低減するために、なる
べく素材に予加工を加えないようにしながら製管する技
術については、例えば特開平1−228603号公報に
記載されるように特定の鋼種、ここでは2相ステンレス
鋼に対し連続鋳造された丸ビレットの加工度および加熱
温度を限定するといった先行技術や、特開平6−106
209号公報のように穿孔機およびプラグからなる幾何
学的関係より穿孔圧延方法を開示している先行技術もあ
る。後者は素材を限定せず、一見かなり有効な提案であ
るように見える。ところが素材品質が劣悪である場合に
は、鉄と鋼、第56年第7号「継目無鋼管の製造技術に
ついて」(以下先行技術5)等において記されているよ
うに、内面疵を抑制し得るある圧下率が存在し、少なく
とも材質の特性を把握しなくてはならないため、このよ
うな提案は全く無力に等しい。なぜならばマンネスマン
穿孔という過酷な加工を受けるが故に、内面疵の発生源
ともなるビレット軸芯部の状態は、素材の鋼種あるいは
製法によって全く異なるからである。
Further, in order to reduce the manufacturing cost, a technique for producing a pipe while preforming the material as little as possible is described in, for example, Japanese Patent Application Laid-Open No. 1-228603. In Japanese Patent Application Laid-Open No. 6-106, Japanese Patent Application Laid-Open No. 6-106 discloses a method of limiting the working degree and heating temperature of a round billet continuously cast on a duplex stainless steel.
There is also a prior art which discloses a piercing and rolling method based on a geometric relationship between a piercing machine and a plug as disclosed in Japanese Patent Publication No. 209/209. The latter does not limit the material and appears to be a fairly effective proposal at first glance. However, when the material quality is inferior, as described in Iron and Steel, No. 56, No. 7, "Technology for manufacturing seamless steel pipe" (hereinafter referred to as Prior Art 5), inner surface flaws are suppressed. Since there is a certain reduction ratio to be obtained and at least the properties of the material must be grasped, such a proposal is completely ineffective. This is because the state of the billet shaft core, which is a source of inner surface flaws, is completely different depending on the type of steel or the manufacturing method of the material, because it undergoes severe processing called Mannesmann drilling.

【0013】しかしながら直鋳ままの素材、特にそれが
高合金鋼であるような場合にはビレット内質の劣化が著
しく、先行技術5に示されたような圧下率ではとても内
面疵は抑制できないのが現状である。また、その圧下率
を取るべく、穿孔条件を変更しようとしても、今度は素
材が噛込み不良を起こしてしまい、結局、内面疵の抑制
を行えないという問題があった。
However, when the material is directly cast, especially when it is a high alloy steel, the internal quality of the billet is significantly deteriorated, and the inner surface flaw cannot be suppressed very much at the rolling reduction shown in the prior art 5. Is the current situation. Further, even if it is attempted to change the drilling conditions in order to obtain the rolling reduction, there is a problem in that the material may cause a biting failure this time, and as a result, the inner surface flaw cannot be suppressed.

【0014】[0014]

【発明が解決しようとする課題】以上述べたように、従
来の素材製造・製管工程により内面品質の良い製品を得
るためには、素材に予加工を与える必要があるが、予加
工をするための特別な設備投資が必須となりコストが上
昇するデメリットがある。一方、素材内質の悪い部分を
容認しつつ製管しようとするならば、比較的大がかりな
設備改造を等を伴うことや、素材一つ一つに加工をする
必要が生じ、やはりコスト負担は免れ得ずデメリットが
発生する問題点があった。従って、ほぼ従来通りの工程
を経ながら難加工材、特に鋳造ままの高合金鋼などを製
管後も、管内面疵を残さないようにすることは極めて困
難であった。従って、可能な限り直鋳ままなどの予加工
を施さない素材を用い、かつ穿孔で内面疵を作らず、そ
れを大きな設備投資なく製造できる、コスト増のデメリ
ットを解決する技術が切望されていた。
As described above, in order to obtain a product with good inner surface quality by the conventional material manufacturing and pipe making processes, it is necessary to pre-process the material. Therefore, there is a demerit that special capital investment is indispensable and the cost increases. On the other hand, if pipes are to be manufactured while accepting parts with poor internal quality of materials, it will be necessary to remodel equipment relatively extensively, and it will be necessary to process each material one by one. There is a problem that disadvantages occur because they cannot be avoided. Therefore, it has been extremely difficult to prevent the flaws on the inner surface of the pipe even after the production of a difficult-to-machine material, particularly a high-alloy steel as cast, while passing through substantially the same process. Therefore, there has been a long-felt need for a technology that solves the disadvantage of increased cost, using a material that is not subjected to pre-processing such as as-cast as much as possible, and that can be manufactured without a large capital investment without making internal flaws by drilling. .

【0015】[0015]

【課題を解決するための手段】本発明はかかる事情に鑑
み、難加工材や鋳造ままの素材を、コスト負担増のデメ
リットを生じさせることのない極めて合理的な手段で従
来通りの製造を行い、かつ管内面疵を抑制するため、既
存設備を最大限利用することを検討した。その結果、上
記課題を達成する本願発明の特徴は、鋳造ままの丸鋳片
など内質劣化の著しい素材を用いることで素材コストの
抑制を行い、該素材を穿孔するにあたりプラグによる抗
力のために傾斜穿孔圧延時に素材が噛込まない場合、プ
ッシャーにより素材に背圧を付与しながら押し込みつつ
マンネスマン穿孔を行うことで内面疵を防止することを
特徴とする継目無管の製造方法である。以下に本願発明
の原理を説明する。
SUMMARY OF THE INVENTION In view of the foregoing, the present invention provides a conventional method for manufacturing difficult-to-machine materials and as-cast materials by extremely rational means without causing a disadvantage of increasing the cost burden. In order to suppress the flaws on the inner surface of the pipe, we considered using the existing equipment to the maximum. As a result, the feature of the present invention that achieves the above-mentioned object is to suppress the material cost by using a material with remarkably deteriorated internal quality such as a round cast slab as cast, and to reduce the resistance by a plug when drilling the material. A method for manufacturing a seamless pipe, characterized in that when a material does not bite during inclined piercing and rolling, inner surface flaws are prevented by performing Mannesmann piercing while pushing while applying back pressure to the material with a pusher. Hereinafter, the principle of the present invention will be described.

【0016】先に述べた先行技術等の知見を元にすれ
ば、加工性の劣悪な素材を疵なく穿孔・製管するには、
軽圧下穿孔が必要であることが示唆されている。これを
実現するためには、穿孔プラグを素材側へ前進させ、軽
圧下状態を作り出すことが必要になる。このことは、一
見矛盾するが、傾斜穿孔圧延法を用いながらマンネスマ
ン効果、すなわち回転鍛造効果をできる限り抑制しつつ
穿孔すれば如何なる素材に対しても内面疵を生ずること
なく製管することが可能となることを意味している。
[0016] Based on the above-mentioned knowledge of the prior art and the like, in order to pierce and form a material having poor workability without flaws,
It has been suggested that perforation under light pressure is necessary. In order to realize this, it is necessary to advance the perforated plug toward the material side to create a lightly reduced state. Although this is seemingly contradictory, it is possible to produce pipes without any internal flaws in any material by drilling while using the inclined piercing and rolling method while suppressing the Mannesmann effect, that is, the rotary forging effect as much as possible. It means that it becomes.

【0017】そこで、本願発明者等は、鋭意研究を重
ね、従来よりも遥かに小さい圧下で穿孔を可能にし、内
面疵を抑制できる技術を見出した。それは、従来より穿
孔に用いられていたプッシャーを最大限に利用し、噛込
み不良が生じた場合にのみさらにプッシャーによってロ
ールへ材料を押し込むことで内面疵を抑制する穿孔法お
よびそれにより得られる継目無管である。プッシャーは
本来、素材を傾斜穿孔機まで搬送する目的で設けられて
おり、穿孔ロールへ素材ビレットを噛込ませると自動的
に後退したり、手動運転時にはオペレータが手動で後退
させている。この場合の噛込みとは、回転する穿孔ロー
ルと素材ビレットが接触すると素材ビレットにスパイラ
ルな回転運動が付与されることにより、自動的に開始さ
れるものであり、噛込みが開始した後はプッシャーが素
材ビレットの回転運動を妨げるとする理論より直ちに後
退させており、搬送以外に特に意味を持つものではな
い。
Therefore, the inventors of the present application have conducted intensive studies and have found a technique capable of perforating under a much lower pressure than conventional techniques and suppressing internal flaws. It is a perforation method that uses the pusher that has been conventionally used for perforation to the utmost, and suppresses inner surface flaws by pushing the material into the roll by the pusher only when poor biting occurs and the seam obtained by it. It is tubeless. The pusher is originally provided for the purpose of transporting the material to the inclined punch. The pusher is automatically retracted when the material billet is bitten into the punching roll, or is manually retracted by the operator during manual operation. In this case, the biting is started automatically when the rotating billet roll comes into contact with the material billet, thereby giving a spiral rotation to the material billet. Is immediately retracted from the theory that it hinders the rotational movement of the material billet, and has no special significance other than transport.

【0018】一方、穿孔プラグを素材側へ前進させ素材
を軽圧下にて穿孔する場合には、ロール・素材間の摩擦
力によって駆動されていた素材が穿孔プラグと接触する
ことにより抗力が発生し、これがロールより素材に与え
られる駆動力に勝るため噛込み不良となる。噛込み不良
の要因としては、穿孔プラグによる抗力以外にも、ロー
ル・素材間の摩擦力の不足に起因する素材への駆動力の
伝達不十分も考えられる。しかしながら、摩擦力を増加
させることでこの問題を解決しようとする試みについて
は、既に穿孔ロール表面にはよく知られているナーリン
グと呼ばれる凹凸あるいはローレットと呼ばれる表面加
工痕があるため、経時変化によるロール表面の変動を除
けば、噛込みに大きな影響を与えることはできなかっ
た。
On the other hand, when the piercing plug is advanced to the material side to pierce the material under light pressure, a drag is generated by the material driven by the frictional force between the roll and the material coming into contact with the piercing plug. This is superior to the driving force applied to the material from the roll, resulting in poor biting. The cause of the poor biting may be insufficient transmission of driving force to the material due to insufficient frictional force between the roll and the material, in addition to the drag by the perforated plug. However, in an attempt to solve this problem by increasing the frictional force, the surface of the perforated roll already has a well-known unevenness called knurling or a surface processing mark called knurl, so that the roll due to aging changes. Except for surface variations, the bite could not be significantly affected.

【0019】そこで、改めて穿孔プラグによる抗力の問
題を十分検討したところ、図1(a)に示すように噛込
み不良が生じた状態と、図1(b)に示す通常の穿孔状
態での違いは、通常穿孔時の素材変形により得られるロ
ール・素材間の接触面積が異なることに起因する駆動力
と抗力のバランスだけである。この点に本願発明者等は
着目し、図1(c)に示すように噛込み不良が生じない
ようにプッシャーにより、穿孔プラグの抗力に打ち勝つ
だけの背圧を付与し、穿孔可能な状態の接触面積が確保
でき穿孔が通常通り進行することを可能にすることで、
軽圧下穿孔、すなわち内面疵の抑制を可能にできること
を見出した。
Therefore, when the problem of the drag caused by the perforated plug was thoroughly examined again, the difference between the state in which the biting failure occurred as shown in FIG. 1A and the normal perforated state shown in FIG. Is only the balance between the driving force and the drag force resulting from the difference in the contact area between the roll and the material obtained by the deformation of the material at the time of drilling. The inventors of the present application pay attention to this point, and apply a back pressure enough to overcome the drag of the piercing plug with a pusher so as to prevent a poor biting as shown in FIG. By securing the contact area and allowing drilling to proceed as usual,
It has been found that perforation under light pressure, that is, suppression of inner surface flaws can be achieved.

【0020】なお、一般炭素鋼の直鋳材でも本発明の適
用により噛込み不良がなくなることはもちろん、内面疵
の発生率をほぼ0にすることが可能となった。また、内
質が劣化しやすい硫黄を多く含んだ炭素鋼や高合金鋼な
どの難加工材、またその直鋳材についても内面疵の発生
を従来の炭素鋼並に抑制できることが認められた。
It should be noted that the application of the present invention not only eliminates poor biting, but also makes it possible to reduce the incidence of inner surface flaws to almost zero even in the case of direct cast steel of general carbon steel. In addition, it was also recognized that the occurrence of inner surface flaws can be suppressed to the same level as that of conventional carbon steel even for difficult-to-machine materials such as carbon steel and high alloy steel containing a large amount of sulfur, whose internal quality is apt to deteriorate, and also for direct cast materials.

【0021】[0021]

【発明の実施の形態】図2は穿孔プラグにかかるスラス
ト荷重および穿孔ロール荷重を示すグラフ図である。図
2(a)は噛込み不良が生じた場合の穿孔プラグにかか
るスラスト荷重および穿孔ロール荷重を示すもので、こ
こでは、素材が穿孔ロールに噛込むとほぼ同時に、穿孔
プラグにも荷重がかかり始め、時間が経過しても素材が
穿孔ロールに噛込んでいかない様子を示している。一
方、図2(b)には通常穿孔時の荷重を示しているが、
ここではロール荷重が十分大きくなる、すなわち接触面
積が十分に大きくなった後、穿孔プラグと接触している
ことが示されている。
FIG. 2 is a graph showing a thrust load and a piercing roll load applied to a piercing plug. FIG. 2A shows the thrust load and the piercing roll load applied to the piercing plug when a biting failure occurs. Here, the load is applied to the piercing plug almost simultaneously with the material being bitten into the piercing roll. At first, it shows a state in which the material does not bite into the perforating roll even after a lapse of time. On the other hand, FIG. 2B shows the load at the time of normal drilling,
Here, it is shown that, after the roll load becomes sufficiently large, that is, the contact area becomes sufficiently large, the roll comes into contact with the perforated plug.

【0022】そこで、本件発明を適用すると図2(c)
に示したとおり、噛込み初期は噛込み不良時と同じ荷重
変動を示しているが、A時点でプッシャーにより素材後
方から背圧を付与し始めると、ロール荷重、プラグ荷重
ともに増大を始め、途中から通常穿孔状態に移行してい
ることがわかる。なお、プッシャーはロール荷重が増大
を始めるB時点、すなわち接触面積を確保し始めた段階
で後退しているため、穿孔プラグに余計な負荷はかかっ
ていない。このため、素材後方から背圧を付与しても高
合金鋼穿孔で懸念される、耐用度の減少をもたらすこと
はない。また、通常穿孔時に想定されるロール・各種ガ
イドシュー間への素材噛出しに伴うトラブルは、軽圧下
穿孔であるために押込みを行っても生じない。
Therefore, when the present invention is applied, FIG.
As shown in, the initial load shows the same load fluctuation as at the time of poor biting, but when the back pressure starts to be applied from behind the material by the pusher at the point A, both the roll load and the plug load start to increase, and It can be seen from FIG. 7 that the state has shifted to the normal perforation state. Since the pusher is retracted at the point B at which the roll load starts to increase, that is, at the stage when the contact area is started to be secured, no extra load is applied to the perforated plug. For this reason, even if the back pressure is applied from the back of the material, the durability does not decrease, which is a concern in drilling high alloy steel. In addition, troubles caused by material escaping between rolls and various guide shoes, which are assumed at the time of normal drilling, do not occur even when pushing is performed because the drilling is performed under light pressure.

【0023】[0023]

【実施例】実施例1.熱間モデル穿孔機で本願発明につ
いて従来技術と比較を行った。素材ビレットには、鋳造
ままの0.4%炭素鋼を用い、素材加熱温度は1250
℃、ロール入側面角は2.5度、ロール傾斜角は7度の
条件にて穿孔実験を実施した。この結果を表1に示す。
なお、内面不良に関しては、各水準100本の穿孔を行
い、総圧延本数当たりの疵発生本数の比率を不良率とし
て評価し、その発生率が15%以上である場合を×、5
%以上〜15%未満を△、1%以上〜5%未満を○、さ
らに今回の試験中には疵発生がなかったものを◎とし
た。比較例ではプラグ先端圧下率の増加とともに、やや
内面疵が減少する傾向が見られたが、94%の噛込み不
良域直前でも不良率は12%と疵の抑制は完全ではな
い。しかしながら本発明の適用により、噛込み限界が向
上し、プラグ先端圧下率95.5%では完全に内面疵の
ない穿孔が可能となった。ここでプラグ先端圧下率と
は、下式で定義される指標を指すものとする。
[Embodiment 1] The present invention was compared with the prior art using a hot model drilling machine. For the material billet, 0.4% carbon steel as cast is used, and the material heating temperature is 1250.
A perforation experiment was carried out under the conditions of ° C, a roll entering side angle of 2.5 degrees and a roll inclination angle of 7 degrees. Table 1 shows the results.
Regarding the inner surface defect, 100 holes were drilled at each level, and the ratio of the number of flaws generated per total rolling number was evaluated as a defective rate.
% To less than 15%, ○: 1% to less than 5%, and ◎: no flaw during the test. In the comparative example, the internal surface flaws tended to decrease slightly with an increase in the plug tip reduction rate, but the defect rate was 12% immediately before the 94% biting failure area, and the suppression of flaws was not complete. However, by the application of the present invention, the biting limit was improved, and drilling completely free from internal flaws was possible at a plug tip reduction rate of 95.5%. Here, the plug tip reduction rate indicates an index defined by the following equation.

【0024】プラグ先端圧下率=プラグ先端位置でのロ
ール間隔/素材ビレット径 この定義によれば、穿孔ロール形状が樽型であることを
考慮すると、プラグ位置を素材入側へ前進させることは
プラグ先端でのロール間隔が拡がることと等しく、プラ
グ先端圧下率を増加させることと一致する。また、素材
ビレット径は変わらないから、ロール間隔が広くなるこ
とは軽圧下状態を作り出していることとも一致する。従
って上記結果、すなわち本発明の適用が内面疵の低減に
つながることを本実施例では表している。
According to this definition, considering that the shape of the perforation roll is barrel-shaped, it is not possible to advance the plug position to the material entry side by the plug tip reduction rate / roll interval at the plug tip position / material billet diameter. This is equivalent to increasing the roll interval at the tip, which is consistent with increasing the plug tip rolling reduction. Also, since the material billet diameter does not change, an increase in the roll interval is consistent with the fact that a lightly reduced state is created. Therefore, the present embodiment shows that the above result, that is, the application of the present invention leads to a reduction in inner surface flaws.

【0025】[0025]

【表1】 [Table 1]

【0026】実施例2.同様の穿孔条件で穿孔実験を実
施した結果を表2に示す。素材に鋳造ままの13%Cr
鋼および従来通りの予加工を施した13%Cr鋼材を穿
孔した場合には、噛込み不良直前の94%で不良率が1
0%弱と工業生産を行う上ではやや高い結果を示した。
一方、直鋳ままの比較例では、同じ穿孔条件でも不良率
が50%と非常に高く、工業生産は成り立たない。しか
しながら、本発明を適用すると、予加工材で95%のプ
ラグ先端圧下率で不良率1%、95.5%では無疵で製
管可能となり、実機でもほぼ無手入れの状態で製造が可
能となる見通しを得た。また、直鋳ままの素材について
は、プラグ先端圧下率97%で不良率を1%に、また9
7.55%では不良率0%で製管でき、素材予加工のコ
ストをそのまま低減させることが可能となった。
Embodiment 2 FIG. Table 2 shows the results of a drilling experiment performed under the same drilling conditions. 13% Cr as cast in the material
In the case of drilling steel and 13% Cr steel that had been subjected to conventional pre-processing, the defect rate was 1 at 94% immediately before biting failure.
The result was slightly higher than 0% for industrial production.
On the other hand, in the comparative example directly cast, the defect rate was as high as 50% even under the same drilling conditions, and industrial production was not feasible. However, when the present invention is applied, the pre-processed material can be manufactured with a defect rate of 1% at a plug tip reduction rate of 95% and a flawless tube at 95.5%, and can be manufactured with almost no care in an actual machine. I got the prospect. For the as-cast material, the defect rate was reduced to 1% at a plug tip reduction rate of 97% and 9%.
At 7.55%, pipes can be made with a defect rate of 0%, and the cost of raw material pre-processing can be reduced as it is.

【0027】[0027]

【表2】 [Table 2]

【0028】[0028]

【発明の効果】従来熱間加工性が劣悪で継目無管材とし
て不適当であった難加工材または鋳造ままであるため素
材中心部にザク等が存在する品質の悪い素材を穿孔圧延
するに際し、設備に大幅な変更を加えることなく穿孔条
件を最適化することを可能とし、これにより管内面疵を
なくし、付加価値の高い高合金鋼鋼管等のコスト低減お
よび生産性向上を可能にせしめる技術を提供できる。
According to the present invention, when piercing and rolling a poor-quality material having poor hot workability and being unsuitable as a seamless pipe material or a poor quality material having a zaku or the like in the center of the material because it is still cast, Technology that enables the optimization of drilling conditions without making significant changes to the equipment, thereby eliminating flaws on the inner surface of the pipe and enabling cost reduction and productivity improvement of high value-added high alloy steel pipes Can be provided.

【図面の簡単な説明】[Brief description of the drawings]

【図1】マンネスマン穿孔機での穿孔状態を示す説明図
である。
FIG. 1 is an explanatory view showing a perforated state in a Mannesmann perforator.

【図2】穿孔プラグにかかるスラスト荷重および穿孔ロ
ール荷重を示すグラフ図である。
FIG. 2 is a graph showing a thrust load and a piercing roll load applied to a piercing plug.

【図3】Cr含有量と溶鋼の粘性との関係を示すグラフ
図である。
FIG. 3 is a graph showing the relationship between the Cr content and the viscosity of molten steel.

【符号の説明】[Explanation of symbols]

1 素材ビレット 2 穿孔ロール 3 穿孔プラグ 4 プッシャー Reference Signs List 1 material billet 2 punch roll 3 punch plug 4 pusher

フロントページの続き (72)発明者 小田 龍晴 東京都千代田区丸の内一丁目1番2号 日 本鋼管株式会社内 (72)発明者 岡本 芳秀 東京都千代田区丸の内一丁目1番2号 日 本鋼管株式会社内 (72)発明者 安川 雅彦 東京都千代田区丸の内一丁目1番2号 日 本鋼管株式会社内 (72)発明者 杉山 努 東京都千代田区丸の内一丁目1番2号 日 本鋼管株式会社内Continued on the front page (72) Inventor Tatsuharu Oda 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd. (72) Inventor Yoshihide Okamoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Inside Kokan Co., Ltd. (72) Inventor Masahiko Yasukawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Inside Nihon Kokan Co., Ltd. In company

Claims (8)

【特許請求の範囲】[Claims] 【請求項1】 鋳造ままの丸鋳片を用いて、プラグによ
る抗力のために傾斜穿孔圧延時に素材が噛込まない場
合、プッシャーによって素材に背圧を付与しながら安定
に噛込むまで押し込みつつ穿孔を行うことで内面疵を防
止することを特徴とする方法により製造された継目無
管。
1. When a material is not bitten at the time of inclined piercing and rolling due to a drag by a plug using an as-cast round slab, a hole is pierced while being pressed until a stable pressure is obtained while applying a back pressure to the material by a pusher. A seamless pipe manufactured by a method characterized by preventing inner surface flaws by performing the following.
【請求項2】 鋳造ままの丸鋳片を用いて、プラグによ
る抗力のために傾斜穿孔圧延時に素材が噛込まない場
合、プッシャーによって素材に背圧を付与しながら安定
に噛込むまで押し込みつつ穿孔を行うことで内面疵を防
止することを特徴とする継目無管製造方法。
2. When a raw material is not bitten at the time of inclined piercing and rolling due to a drag by a plug using a round cast slab as cast, it is pierced while pushing the material stably while applying a back pressure by applying a back pressure. A seamless pipe manufacturing method characterized by preventing internal surface flaws by performing the following.
【請求項3】 難加工材の丸鋳片を用いて、プラグによ
る抗力のために傾斜穿孔圧延時に素材が噛込まない場
合、プッシャーによって素材に背圧を付与しながら安定
に噛込むまで押し込みつつ穿孔を行うことで内面疵を防
止することを特徴とする方法により製造された継目無
管。
3. When a material does not bite during inclined piercing and rolling due to drag by a plug using a round cast piece of a difficult-to-process material, the material is pushed back while applying a back pressure to the material by a pusher until the material is stably bitten. A seamless pipe manufactured by a method characterized by preventing internal flaws by piercing.
【請求項4】 Crの含有量が0.5%を超え、かつC
r、NiおよびMoの含有量合計が1%を超える鋳造ま
まの丸鋳片を用いて、プラグによる抗力のために傾斜穿
孔圧延時に素材が噛込まない場合、プッシャーによって
素材に背圧を付与しながら安定に噛込むまで押し込みつ
つ穿孔を行うことで内面疵を防止することを特徴とする
方法により製造された継目無管。
4. The method according to claim 1, wherein the content of Cr exceeds 0.5%,
When as-cast round slabs having a total content of r, Ni and Mo exceeding 1% are used, when the material does not bite during inclined piercing and rolling due to drag by a plug, back pressure is applied to the material by a pusher. A seamless pipe manufactured by a method characterized by preventing internal flaws by piercing while pushing it in until it stably engages.
【請求項5】 Crの含有量が0.5%を超え、かつC
r、NiおよびMoの含有量合計が2.5%を超える丸
鋳片、もしくはCrの含有量が0.5%を超え、かつC
r、NiおよびMoの含有量合計が1%以上でSを0.
001%以上含有する難加工材の丸鋳片を用いて、プラ
グによる抗力のために傾斜穿孔圧延時に素材が噛込まな
い場合、プッシャーによって素材に背圧を付与しながら
安定に噛込むまで押し込みつつ穿孔を行うことで内面疵
を防止することを特徴とする方法により製造された継目
無管。
5. The method according to claim 1, wherein the content of Cr exceeds 0.5%, and
A round slab having a total content of r, Ni and Mo exceeding 2.5%, or a content of Cr exceeding 0.5% and C
When the total content of r, Ni and Mo is 1% or more, S is set to 0.1%.
When the material does not bite at the time of inclined piercing and rolling due to the drag by the plug using a round cast piece of hard-to-process material containing 001% or more, while pushing the material stably while applying back pressure by the pusher, A seamless pipe manufactured by a method characterized by preventing internal flaws by piercing.
【請求項6】 難加工材の丸鋳片を用いて、プラグによ
る抗力のために傾斜穿孔圧延時に素材が噛込まない場
合、プッシャーによって素材に背圧を付与しながら安定
に噛込むまで押し込みつつ穿孔を行うことで内面疵を防
止することを特徴とする継目無管製造方法。
6. When using a round cast piece of a difficult-to-process material, when the material does not bite during inclined piercing and rolling due to drag by a plug, the material is pressed down while applying back pressure to the material stably until it bites in. A method for manufacturing a seamless pipe, wherein inner surface flaws are prevented by performing perforation.
【請求項7】 Crの含有量が0.5%を超え、かつC
r、NiおよびMoの含有量合計が1%を超える鋳造ま
まの丸鋳片を用いて、プラグによる抗力のために傾斜穿
孔圧延時に素材が噛込まない場合、プッシャーによって
素材に背圧を付与しながら安定に噛込むまで押し込みつ
つ穿孔を行うことで内面疵を防止することを特徴とする
継目無管製造方法。
7. The method according to claim 1, wherein the content of Cr exceeds 0.5% and
When as-cast round slabs having a total content of r, Ni and Mo exceeding 1% are used, when the material does not bite during inclined piercing and rolling due to drag by a plug, back pressure is applied to the material by a pusher. A method for manufacturing a seamless pipe, characterized in that inner surface flaws are prevented by piercing while pushing in while stably engaging.
【請求項8】 Crの含有量が0.5%を超え、かつC
r、NiおよびMoの含有量合計が2.5%を超える丸
鋳片、もしくはCrの含有量が0.5%を超え、かつC
r、NiおよびMoの含有量合計が1%以上でSを0.
001%以上含有する難加工材の丸鋳片を用いて、プラ
グによる抗力のために傾斜穿孔圧延時に素材が噛込まな
い場合、プッシャーによって素材に背圧を付与しながら
安定に噛込むまで押し込みつつ穿孔を行うことで内面疵
を防止することを特徴とする継目無管製造方法。
8. The method according to claim 1, wherein the content of Cr exceeds 0.5%, and
A round slab having a total content of r, Ni and Mo exceeding 2.5%, or a content of Cr exceeding 0.5% and C
When the total content of r, Ni and Mo is 1% or more, S is set to 0.1%.
When the material does not bite at the time of inclined piercing and rolling due to the drag by the plug using a round cast piece of hard-to-process material containing 001% or more, while pushing the material stably while applying back pressure by the pusher, A method for manufacturing a seamless pipe, wherein inner surface flaws are prevented by performing perforation.
JP16681598A 1998-06-15 1998-06-15 Seamless tube and its manufacture Pending JP2000000605A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP16681598A JP2000000605A (en) 1998-06-15 1998-06-15 Seamless tube and its manufacture

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP16681598A JP2000000605A (en) 1998-06-15 1998-06-15 Seamless tube and its manufacture

Publications (1)

Publication Number Publication Date
JP2000000605A true JP2000000605A (en) 2000-01-07

Family

ID=15838186

Family Applications (1)

Application Number Title Priority Date Filing Date
JP16681598A Pending JP2000000605A (en) 1998-06-15 1998-06-15 Seamless tube and its manufacture

Country Status (1)

Country Link
JP (1) JP2000000605A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012060358A1 (en) * 2010-11-02 2012-05-10 住友金属工業株式会社 Method of detecting defects in rotary piercing, seamless pipe manufacturing method
CN111069298A (en) * 2019-12-19 2020-04-28 太原重工股份有限公司 Digital control system and method for puncher
CN112501522A (en) * 2020-11-06 2021-03-16 宁波市海曙文昌金属制品有限公司 High-temperature-resistant piercing plug and preparation method thereof

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012060358A1 (en) * 2010-11-02 2012-05-10 住友金属工業株式会社 Method of detecting defects in rotary piercing, seamless pipe manufacturing method
JP2012096265A (en) * 2010-11-02 2012-05-24 Sumitomo Metal Ind Ltd Method of detecting defects in rotary piercing and seamless pipe manufacturing method
US9333545B2 (en) 2010-11-02 2016-05-10 Nippon Steel & Sumitomo Metal Corporation Method of detecting fault in piercing-rolling and method of producing seamless pipe or tube
CN111069298A (en) * 2019-12-19 2020-04-28 太原重工股份有限公司 Digital control system and method for puncher
CN111069298B (en) * 2019-12-19 2021-10-08 太原重工股份有限公司 Digital control system and method for puncher
CN112501522A (en) * 2020-11-06 2021-03-16 宁波市海曙文昌金属制品有限公司 High-temperature-resistant piercing plug and preparation method thereof
CN112501522B (en) * 2020-11-06 2022-05-31 宁波市海曙文昌金属制品有限公司 High-temperature-resistant piercing plug and preparation method thereof

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