JPH02284728A - Production of double-pipe reducer pipe joint - Google Patents

Abstract

PURPOSE:To suppress the generation of wrinkle of an inside pipe and to improve the threshold of a pipe reducing by fitting a restrain pipe to the inner side of double pipes, integrating only the front end on a reducing side by welding to form triple pipes, the inside pipe of which is shortened on a pressing side, and then pressing only the outside pipe and the restraining pipe. CONSTITUTION:The restraining pipe 3 is fitted to the inner side of the double pipes mechanically joined with the outside pipe 1 and the inside pipe 2 of >=50 ratio between the outside diameter and thickness at the boundary. Only the front end on the drawing side of the outside pipe 1, the inside pipe 2 and the restraining pipe 3 is then integrated by the welding W. The triple pipes, the inside pipe 2 of which is shorter than the outside pipe 1 and the restraining pipe 3 on the pressing side, are thus formed. The triple pipes are reduced by pressing only the outside pipe 1 and the restraining pipe 3. Since the axial tensile load acts on the inside pipe 2, the circumferential stress necessary for deformation decreases and further, the generation of buckling is suppressed. The front end on the drawing side is cut after the pressing and the restraining pipe 3 is removed by pressing to form the double pipes. The reducer is finished by further cutting the two pipe ends.

Description

【発明の詳細な説明】 ［産業上の利用分野］ 本発明は石油、天然ガスの生産に必要な配管部材に係わ
るものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to piping members necessary for the production of oil and natural gas.

［従来の技術］ 近年の石油或は天然ガスの掘削環境は硫化水素或は炭酸
ガスを多量に含んでおり、ここに使用される調料は高合
金鋼が主体になりつつある。高合金鋼は高価であること
から、低コストで、かつ、高耐食性を有する鋼管、即ち
、鋼管の内面に高合金鋼を外面に炭素鋼を配したメカニ
カルな二重管が開発されている。一方、これらの鋼管の
配管に必要な溶接式管継手の一つであるレデューサ管継
手（大別して同心レデューサと偏心レデューサがあり、
総称して以下レデューサとする）も高合金の単一管から
製造するのでは高価であるし、また、二重管との配管溶
接上、異種金属溶接の難しさから二重管構造のレデコ５
−サが望まれている。にも係わらず、この様なメカニカ
ルに接合された二重管からレデューサを製造する方法は
未だ検討されていｔ２い。[Prior Art] In recent years, the oil or natural gas drilling environment contains large amounts of hydrogen sulfide or carbon dioxide gas, and the preparations used therein are becoming mainly made of high-alloy steel. Since high-alloy steel is expensive, a low-cost steel pipe with high corrosion resistance has been developed, that is, a mechanical double-walled pipe in which high-alloy steel is arranged on the inner surface of the steel pipe and carbon steel is arranged on the outer surface. On the other hand, reducer pipe joints are one of the welded pipe joints required for piping these steel pipes (roughly divided into concentric reducers and eccentric reducers,
(hereinafter collectively referred to as reducers) is expensive if manufactured from a single high-alloy tube, and due to the difficulty of welding dissimilar metals with double tubes, the double tube structure Redeco 5
-Sa is desired. Nevertheless, a method of manufacturing a reducer from such mechanically joined double pipes has not yet been studied.

［発明が解決しようとする課題］ 従来、単一鋼管からのレデューサの製造方法は低コスト
で加工できることから、一般に、第２図に示すように、
ダイ４の入・口径より小さい外径の管５がブツシャ−６
により下方ヘプレスされ、管５はダイの内側の形状に沿
って所定のレデューサ形状まで縮管成形され、この後、
成形されたレデューサは下方より押上げて取り出され、
両端を機械加工により仕上げられて製品となる。いわゆ
る、プレス方式が採用されている。[Problems to be Solved by the Invention] Conventionally, a method for manufacturing a reducer from a single steel pipe is generally performed as shown in FIG. 2 because it can be processed at low cost.
A tube 5 with an outer diameter smaller than the input/bore diameter of the die 4 is a bushing 6.
The tube 5 is pressed downward to a predetermined reducer shape along the inner shape of the die, and then,
The molded reducer is pushed up from below and taken out.
Both ends are finished by machining to create the product. A so-called press method is used.

一方、特開昭５７−１４４３１号公報によれば、金属円
板から絞り加工してレデューサを成形する方法もあるが
、本発明では二重管を素材とする場合に有利であるプレ
ス方式に着目して改善を加えた。On the other hand, according to JP-A-57-14431, there is a method of forming a reducer by drawing from a metal disc, but the present invention focuses on a pressing method, which is advantageous when using a double pipe as a material. and added improvements.

このプレス方式においては、外径−肉厚比が５０以下の
単一鋼管を対象として、技術的に確立されている。しか
しながら、外径−肉厚比が５０以上については十分検討
されていない。従来技術のもとで、内管の外径−肉厚比
が５０以上となる二重管から同心レデューサを成形する
と、即ち、両端スケアカットした二重管のままで、レデ
ューサ成形すると、内管肉厚が薄いため、絞り成形時に
しわ座屈が発生し製品にならない。即ち、従来技術で二
重管の同心レデューサを製造するためには、−回の縮管
量を軽度にして繰返し数を増やすか、あるいは、素管の
二重管の内管肉厚を外径−肉厚比が５０以下と厚くする
かして解決できるが、いずれにしてもコスト的に高価な
ものとなってしまい実用的でないことが判った。This pressing method is technically established for single steel pipes with an outer diameter-to-wall thickness ratio of 50 or less. However, a case where the outer diameter-thickness ratio is 50 or more has not been sufficiently studied. Under the conventional technology, when a concentric reducer is molded from a double tube with an inner tube outer diameter-to-wall thickness ratio of 50 or more, that is, when a reducer is molded with a double tube with both ends square-cut, the inner tube Because the wall thickness is thin, wrinkles buckle during drawing and the product cannot be manufactured. That is, in order to manufacture a double-pipe concentric reducer using conventional technology, it is necessary to increase the number of repetitions by reducing the amount of tube contraction twice, or to increase the inner wall thickness of the double-pipe tube to the outer diameter. - This can be solved by increasing the wall thickness ratio to 50 or less, but in either case, it has been found that the cost is high and it is not practical.

また二重管の偏心レデューサを製造においては、軽度な
縮管量でもしわ座屈が発生して、従来技術では偏心レデ
ューサの製造は不可能であった。Furthermore, in manufacturing a double-pipe eccentric reducer, wrinkle buckling occurs even with a slight amount of tube contraction, making it impossible to manufacture an eccentric reducer using conventional techniques.

本発明は、かかる状況を鑑み、単一な材質からなる鋼管
のレデューサの製造条件に近い条件でも加工が可能であ
る二重管のレデューサの製造方法を提供するものである
。In view of this situation, the present invention provides a method for manufacturing a double-pipe reducer that can be processed under conditions similar to those for manufacturing a steel pipe reducer made of a single material.

［課題を解決するための手段］ 本発明は、上記問題を解決するために、プレス加工時の
内管の座屈変形の防止方法に着目してなされたもので、
その要旨は、 外管と外径−肉厚比が５０以上である内管とが界面にお
いてメカニカルに接合された二重管の縮管プレス加工に
よるレデューサの製造方法において、二重管の内側に内
管を拘束するための拘束管をはめ合わせ、外管と内管と
拘束管の絞り加工側の先端のみを接合して一体化し、更
に、プレス加工側で内管は外管および拘束管より短い三
重管とし、外管および拘束管のみをプレスして三重管を
縮管加工することを特徴とする二重管レデューサの製造
方法にある。[Means for Solving the Problems] In order to solve the above problems, the present invention has been made by focusing on a method for preventing buckling deformation of an inner tube during press working, and includes:
The gist is that, in a method for manufacturing a reducer by tube contraction pressing of a double tube in which an outer tube and an inner tube with an outer diameter-to-wall thickness ratio of 50 or more are mechanically joined at the interface, A restraint tube for restraining the inner tube is fitted, and only the tips of the drawing side of the outer tube, inner tube, and restraint tube are joined and integrated, and furthermore, on the pressing side, the inner tube is separated from the outer tube and the restraint tube. A method for manufacturing a double-pipe reducer, characterized in that the triple-pipe tube is made into a short triple-pipe tube, and the triple-pipe tube is shrunk by pressing only the outer tube and the restraining tube.

［作　　　用］ 以下、この発明の詳細な説明する０両端スケアカットの
ままの二重管からレデューサを製造する場合を考えてみ
る。縮管プレス加工するときに、外管自体が縮管すると
ともに内管をも縮管するために、外管はダイス及び内管
からの面圧を受ける。そのため、外管は加工上内外面か
ら拘束されることがら座屈を起こしにくくなっている。[Function] Hereinafter, a case will be considered in which a reducer is manufactured from a double-walled pipe with both ends left squarely cut, which will explain the present invention in detail. During tube shrinkage press working, the outer tube itself is contracted and the inner tube is also contracted, so the outer tube is subjected to surface pressure from the die and the inner tube. Therefore, the outer tube is restrained from the inner and outer surfaces during processing, making it less likely to buckle.

゛しかしながら、内管の変形は外管からの面圧によって
のみ縮管成形されるため、加工上からは、内管は単管の
加工とほぼ同じ条件で加工される。したがって、内管は
内面の拘束がなく、肉厚が薄くなるとシワ座屈が発生し
易くなる。この様なことから、内管にも内面からの面圧
を付与すべく、二重管の内側に拘束管を加えた三重管構
造とした。これにより、薄肉の内管のシワ発生を抑制す
ることが可能になり、縮管加工限界を向上させることに
なる。However, since the inner tube is deformed only by the surface pressure from the outer tube, the inner tube is processed under almost the same conditions as a single tube. Therefore, the inner tube has no inner surface constraint, and as the wall thickness becomes thinner, wrinkle buckling is more likely to occur. For this reason, in order to apply surface pressure from the inner surface to the inner tube, we adopted a triple tube structure in which a restraining tube was added to the inside of the double tube. This makes it possible to suppress the occurrence of wrinkles in the thin-walled inner tube, thereby improving the tube shrinking processing limit.

また、上記から明らかなように縮管プレス方式で両端ス
ケアカットの三重管からレデューサを製造する場合、縮
管部は軸方向の圧縮応力及び周方向の圧縮応力の二軸応
力状態にあり変形応力が高くなる、即ち、周方向応力を
も高くしないと変形しにくい状態になることから座屈し
やすくなる。そこで、この周方向応力を低減するために
、三重管の内管には軸方向に引張応力を付与することが
有効であるこ・とから、第１図および第２図に示すよう
に三重管の絞り加工先端のみを接合一体止し、プレス側
での内管２は外管１および拘束管３よりやや短くした三
重管構造のレデューサ素管とした。これにより、外管と
拘束管のみをプレスでき、成形時には内管に軸方向の引
張荷重が作用するため、変形に必要な周方向応力の低減
が可能となり、更に座屈発生も抑制され、より加工限界
を向上させることが可能となる。In addition, as is clear from the above, when a reducer is manufactured from a triple pipe with both ends scare-cut using the tube shrinking press method, the tube shrinking section is in a biaxial stress state of compressive stress in the axial direction and compressive stress in the circumferential direction, and is subjected to deformation stress. In other words, unless the stress in the circumferential direction is also increased, it becomes difficult to deform, making it easy to buckle. Therefore, in order to reduce this circumferential stress, it is effective to apply tensile stress in the axial direction to the inner tube of the triple-layered tube.As shown in Figures 1 and 2, the triple-layered tube is Only the drawing tip was joined together and the inner tube 2 on the press side was made slightly shorter than the outer tube 1 and the restraint tube 3 to form a reducer element tube with a triple tube structure. This makes it possible to press only the outer tube and the restraint tube, and since an axial tensile load is applied to the inner tube during forming, it is possible to reduce the circumferential stress required for deformation, and the occurrence of buckling is also suppressed, making it even more effective. It becomes possible to improve the processing limit.

プレス成形後、三重管の絞り加工側の先端を所定の位置
で切断し、絞り加工方向と逆に拘束管のみを押し抜いて
、外管及び内管の二重管とし、さらに、両管端を切削し
てレデューサに仕上げる。After press forming, the tip of the drawing side of the triple tube is cut at a predetermined position, and only the restrained tube is punched out in the opposite direction to the drawing direction to form a double tube with an outer tube and an inner tube. Cut to create a reducer.

［実　施　例］ 以下、本発明の一実施例を第１表に説明する。第１表に
は、グイ半角１０９のダイを用い、材質がＡＰＩ　Ｘ７
０で外径２６７．４＋ｎｎφ、肉厚［ｉ、４ｍｍの外管
に、材質がインコロイ８２５で肉厚３．０ｍｍの内管で
ある二重管を素管とし、−従来法としては両端スケアカ
ットのまま、比較法としては二重管の絞り側のみの管端
に溶接を施したもの、更に、材質は普通鋼で肉厚が４　
、０ｍｍ拘束管を接合した本発明の三重管の方法による
加工限界を、加工後の外径と加工前の外径との比、即ち
、口絞り率で示す。[Example] An example of the present invention will be described below in Table 1. In Table 1, a die with a half-width size of 109 is used, and the material is API X7.
0, an outer tube with an outer diameter of 267.4+nnφ and a wall thickness [i, 4 mm, and an inner tube made of Incoloy 825 with a wall thickness of 3.0 mm. However, as a comparative method, welded only the pipe end on the drawing side of the double pipe, and the material was ordinary steel with a wall thickness of 4.
The machining limit of the triple tube according to the present invention in which 0 mm restraint tubes are joined is shown by the ratio of the outer diameter after machining to the outer diameter before machining, that is, the mouth drawing ratio.

本発明による方法は従来法および比較法に比べてはるか
に加工限界が向上していることがわかった。即ちレデュ
ーサの呼び径（大径Ｘ小径）で例えば大径を１０インチ
とした場合、二重管の同心レデューサを製造する場合に
おいては、比較法で高々８インチの小径側縮径加工が限
界であったのに対して、本発明によると６インチの小径
側を有する同心レデューサの製造が可能となる。また偏
心レデューサを製造する場合においては、従来法、比較
法ともに製品が得られなかったが、本発明によって８イ
ンチの小径側を有する偏心レデューサが製造可能となる
。このように、三重管構造とし、かつ、絞り側の加工先
端を接合一体止する・ことと外管と拘束管をプレスする
ことにより内管の座屈限界の向上に有効であることが示
される。It was found that the method according to the present invention has a much improved processing limit compared to the conventional method and the comparative method. In other words, if the nominal diameter of the reducer (large diameter x small diameter) is 10 inches, for example, when manufacturing a double-pipe concentric reducer, the comparative method can only reduce the diameter of the small diameter side to 8 inches at most. However, according to the present invention, it is possible to manufacture a concentric reducer having a small diameter side of 6 inches. In the case of manufacturing an eccentric reducer, neither the conventional method nor the comparative method could produce a product, but the present invention makes it possible to manufacture an eccentric reducer having a small diameter side of 8 inches. This shows that it is effective to improve the buckling limit of the inner tube by creating a triple tube structure, joining and fixing the processed tip on the drawing side, and pressing the outer tube and restraint tube. .

なお、第１表より明らかなように、拘束管のない二重管
においても絞り加工側を溶接し、かつ、外管のみをプレ
ス加工することにより、スケアカットの二重管を成形す
るよりも遥かに有効であるし、内管の肉厚が厚くなれば
、この方法でも十分に実用的である。As is clear from Table 1, by welding the drawn side and pressing only the outer tube even in a double tube without a restraint tube, it is easier to form than a square-cut double tube. This method is much more effective, and if the wall thickness of the inner tube is increased, this method is also fully practical.

本発明によれば、二重管レデューサ成形後に、内管およ
び外管を分離して、それぞれに適正な熱処理を施し、ま
た組み合わせた材質の優れた二重管レデューサも可能で
あるし、更に、内管のみを使用する薄肉レデューサの製
造方法にも適用できることは明らかである。According to the present invention, after forming the double tube reducer, it is possible to separate the inner tube and the outer tube and apply appropriate heat treatment to each, and it is also possible to create a double tube reducer with excellent materials by combining them. It is clear that the present invention can also be applied to a method of manufacturing a thin-walled reducer using only an inner tube.

第　　　１　　　表 ［発明の効果］ この発明の二重管のレデューサの製造方法は、高合金を
使用する過酷な環境において、安価な、かつ、優れた耐
食性を有するレゾユーザを提供することになり、工業の
発展に寄与する顕著な効果がある。Table 1 [Effects of the Invention] The method for manufacturing a double-pipe reducer of the present invention provides a resuser that is inexpensive and has excellent corrosion resistance in harsh environments using high alloys, and is suitable for industrial use. It has a remarkable effect on contributing to the development of the world.

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

第１図は本発明の三重前素管の構成図、第２図は従来の
同心レデューサ成形途中の概念図、第３図は本発明の三
重前素管を用いた偏心レデューサの成形概念図である。 ・・・外管 ３・・・拘束管 Ｗ・・・接合部 ５・・・管 ２・・・内管 ａ・・・隙間 ４・・・ダイ ６・・・ブツシャ− 他４名 第１図 ３Ｆ１束営 ４　タイ ５、管 ６　プツシ７− α　關 Ｗ　按合部Fig. 1 is a configuration diagram of the triple-layered pre-pipe of the present invention, Fig. 2 is a conceptual diagram of a conventional concentric reducer in the middle of forming, and Fig. 3 is a conceptual diagram of forming an eccentric reducer using the triple-ply pre-pipe of the present invention. be. ...Outer tube 3...Restricted tube W...Joint part 5...Pipe 2...Inner tube a...Gap 4...Die 6...Butcher - 4 others Figure 1 3F1 Bundling 4 Tie 5, Pipe 6 Push 7- α Connection W Fitting part

Claims (1)

【特許請求の範囲】[Claims] １　外管と外径−肉厚比が５０以上である内管とが界面
においてメカニカルに接合された二重管の縮管プレス加
工によるレデューサ管継手の製造方法において、二重管
の内側に内管を拘束するための拘束管をはめ合わせ、外
管と内管と拘束管の絞り加工側の先端のみを接合して一
体化し、更に、プレス加工側で内管は外管および拘束管
より短い三重管とし、外管および拘束管のみをプレスし
て三重管を縮管加工することを特徴とする二重管レデュ
ーサ管継手の製造方法。1. In a method for manufacturing a reducer pipe joint by pipe contraction press working of a double pipe in which an outer pipe and an inner pipe having an outer diameter-wall thickness ratio of 50 or more are mechanically joined at the interface, an inner pipe is attached to the inside of the double pipe. Fit the restraining tubes to restrain the tubes, join only the ends of the outer tube, inner tube, and restraining tube on the drawing side to integrate them, and furthermore, the inner tube is shorter than the outer tube and the restraining tube on the press working side. A method for manufacturing a double-pipe reducer pipe joint, characterized in that the triple-pipe pipe is made into a triple-pipe pipe and only the outer pipe and the restraint pipe are pressed to shrink the triple-pipe pipe.