JPH0534084B2 - - Google Patents
Info
- Publication number
- JPH0534084B2 JPH0534084B2 JP59061134A JP6113484A JPH0534084B2 JP H0534084 B2 JPH0534084 B2 JP H0534084B2 JP 59061134 A JP59061134 A JP 59061134A JP 6113484 A JP6113484 A JP 6113484A JP H0534084 B2 JPH0534084 B2 JP H0534084B2
- Authority
- JP
- Japan
- Prior art keywords
- mandrel
- stand
- wall thickness
- diameter
- downstream end
- 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.)
- Expired - Lifetime
Links
- 238000005096 rolling process Methods 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 12
- 229910000831 Steel Inorganic materials 0.000 claims description 7
- 239000010959 steel Substances 0.000 claims description 7
- 238000011144 upstream manufacturing Methods 0.000 claims description 5
- 238000010586 diagram Methods 0.000 description 8
- 238000007796 conventional method Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 230000004043 responsiveness Effects 0.000 description 1
- 239000011265 semifinished product Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B17/00—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling
- B21B17/02—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling with mandrel, i.e. the mandrel rod contacts the rolled tube over the rod length
- B21B17/04—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling with mandrel, i.e. the mandrel rod contacts the rolled tube over the rod length in a continuous process
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Control Of Metal Rolling (AREA)
Description
【発明の詳細な説明】
本発明は、軸方向に均一な肉厚分布を得ること
ができる継目無鋼管のフルフロート式のマンドレ
ルミル方式圧延方法に関する。
一般に、加熱した丸棒鋼を例えばクロスロール
プアシングミルで穿孔して中空粗素管である中空
素管とし、さらにこの中空素管にマンドレルバー
を挿入して、７〜８個のスタンドから成るマンド
レルミルを用いて連続圧延を行い半製品であるシ
エルとする。
従来、継目無網管のマンドレルミル方式圧延方
法では第１図に示されるような上流側も下流側も
同直径dDを有するマンドレルバー３を用いた。
このため、マンドレルバー３の挿入時つまりマン
ドレルバー３の下流端３ａとの接触開始時点から
圧延開始までの時間が短い中空素管の下流端側
は、温度降下が小さいので、ロールギヤツプのス
プリングバツク量も小さく肉厚は薄くなるという
欠点が有つた。
そこで従来、上述の欠点を解消し、軸方向に均
一な肉厚分布の半製品であるシエルを得るための
圧延方法として、(1)マンドレルミルのロール回転
数を変化させて張力制御を行う方法(2)マンドレル
ミルの下流側の仕上げ用のスタンドのロールギヤ
ツプ圧下位置制御を行う方法が提案された。
しかし、上述の(1)の方法はシエルの下流端側一
スタンド間分の材料に対しては相隣り合うスタン
ド間での張力制御が行えず効果がなく、(2)の方法
は圧下制御を行うスタンドのマンドレルミル剛性
を大きくとる必要上マンドレルミルが大型化しコ
ストがかかる上に、例えば油圧シリンダ等の圧下
系の応答性から急激な制御が行えないという欠点
が有つた。
本発明は上述の欠点を解消するために提案され
たもので、シエル下流端側一スタンド間の素管に
対しても肉厚を低コストで簡易に制御できる継目
無鋼管のマンドレル方式圧延方法を提供すること
を目的とする。
以下、本発明の図面を参照してその実施例に基
ずいて説明する。
本発明はマンドレルバーを中空素管に挿入し、
フルフロート式マンドレルミルを用いて、中空素
管の管厚を減少させるに当り、該マンドレルミル
の入り口側スタンドから最終肉厚決定スタンドま
での距離に等しい上流側の長さ部分を正規の直径
としそれより下流端側の直径をスプリングバツク
量に見合つた寸法分縮小したマンドレルバーを用
いて中空素管を連続圧延することを特徴とする継
目無鋼管のマンドレルミル方式圧延方向である。
第２図に示すように、マンドレルミル１は穴型
カリバを有する上下ロール２，２……が90度づつ
交互に向きを変えて配列される。マンドレルミル
では通常、製造すべき鋼管の仕様によつて、管の
最終肉厚決定スタンドが決まつている。従つてマ
ンドレルミルの入り口側スタンドから最終肉厚決
定スタンドまでの距離は、マンドレルミルと鋼管
の種類について固有の値である。マンドレルミル
１において中空素管４を本発明実施例方法で連続
圧延する際に用いられる芯金棒であるマンドレル
レバー３Ｘ，３Ｙ，３Ｚは第３図ａ，ｂ，ｃに示
されるように円筒棒状で下流端３ａが突状形状を
している。シエル下流端側の肉厚変動を補正する
ために、あらかじめマンドレルレバー３Ｘのマン
ドレルミル入口側スタンドから最終肉厚決定スタ
ンドまでの距離に等しい上流側の長さ部分を正規
の直径とし、それにより下流端側の部分の直径を
第３図ａに示されるようにΔαiだけ細くして、直
径dD1となるように段付加工を施す。この場合の
段付量は式(1)によつて求められる。
dD−dD1＝Δαi ……(1)
ただしｉは最終肉厚を決定するスタンドの番号
である。段付加工を施す長さは、マンドレルバー
の全長の内、マンドレルミル入口側スタンドから
最終肉厚決定スタンドまでの距離に等しい上流側
の長さ部分を除いた下流端側の部分である。第７
図はこれを示すもので、中空素管４の先端が最終
肉厚決定スタンド５ｂに到達した状態を示してい
る。マンドレルバー３は、入口側スタンド５ａか
ら最終肉厚決定スタンド５ｂまでの長さＬを正規
の直径としその下流側の長さｌは段付加工を施し
ている。段付加工によつて縮少する直径は管径等
に応じ上記(1)式で決定されるスプリングバツク量
に見合つた寸法で、例えば0.1〜1.0mmである。ま
た、マンドレルバーの直径によつてシエル下流端
側肉厚分布が変るのでシエル下流端側肉厚分布が
テーパ状である場合には、第３図ｂに示されるよ
うに対応するマンドレルバー３Ｙの所定間隔の形
状をテーパ状で下流端３ａの直径がdD1とし、さ
らに肉厚分布が曲線状であれば第３図ｃに示され
るようにマンドレルバー３Ｙの所定間隔の形状が
曲線状で下流端３ａの直径がdD1とすればよい。
マンドレルバー３Ｘ，３Ｙ，３Ｚを中空素管４へ
挿入して、一体となしマンドレルミル１へ噛み込
ませて中空素管４は矢印４ａ方向へ移送され連続
圧延を行う。この際任意のスタンドにおける圧延
状態の模式図が第４図に示される。ロール２，２
……マンドレルバー３Ｘ，３Ｙ，３Ｚによつて外
内面から挟持されている領域をボトム部３ｂ、マ
ンドレルバー３Ｘと接触していない領域をフラン
ジ部３ｃとした場合、中空素管４の肉厚tiはボト
ム部３ｂの領域で式(2)によつて与えられる。
ti＝｛（dki−dD）＋αi）｝／２ ……(2)
dD：マンドレルバー直径
αi：スプリングバツク量
dki：カリバボトム間隔
ここで、圧延下流端側の温度上昇分ΔTsによ
つてスプリングバツク量αiが減少する。スプリン
グバツクの減少量Δαiはスタンド番号によつて定
まる定数のkiを用いて
Δαi＝ki・ΔTs・dD ……(3)
と表される。ここで、カリバボトム間隔dkiが
Δαiだけ変動すると式(2)より肉厚tiはΔαi／２だ
け変動する。第５図にシエル肉厚分布の模式図が
示される。
本実施例方法のシエル外径90mm、シエル肉厚
4.50mmについての諸数値が第１表に示される。上
述の式(2)へ諸数値を代入して、
Δαi＝0.39mm
を得た。従来の第１図のマンドレルバー３を用い
て圧延したシエルの下流端側肉厚分布が第６図ａ
に示され、直径77.5mmで下流端３ａ側3.5ｍの所
定間隔ｌを直径で0.4mm細くなるように段付加工
したマンドレルバー３Ｘを用いて圧延したシエル
の下流端側肉厚分布が第６図ｂに示される。従来
方法によると、平均肉厚に対して約0.2mm薄なつ
たが、マンドレルバー３Ｘを用いることによりほ
ぼ肉厚偏差0.1mmとなつた。
本発明は以上説明したように下流端直径を中央
部直径よりも小さく形成したマンドレルバーを用
いることによりマンドレルミルの下流端側一スタ
ンド間の中空素管に対しても肉厚の制御を低コス
トで簡易に行うことができるという効果を奏す
る。
【表】DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a full-float mandrel mill rolling method for seamless steel pipes that can obtain a uniform wall thickness distribution in the axial direction. Generally, a heated round steel bar is perforated with a cross-roll punching mill to form a hollow blank tube, and a mandrel bar is further inserted into this hollow blank tube to form a mandrel consisting of 7 to 8 stands. Continuous rolling is performed using a mill to produce shells, which are semi-finished products. Conventionally, in the mandrel mill rolling method for seamless mesh pipes, a mandrel bar 3 having the same diameter dD on both the upstream and downstream sides as shown in FIG. 1 has been used.
Therefore, since the temperature drop is small at the downstream end of the hollow tube where the time from the time of insertion of the mandrel bar 3, that is, the time from the start of contact with the downstream end 3a of the mandrel bar 3 to the start of rolling, is small, the spring back amount of the roll gap is reduced. It had the disadvantage that it was smaller and the wall thickness was thinner. Therefore, conventional rolling methods to eliminate the above-mentioned drawbacks and obtain semi-finished shells with uniform wall thickness distribution in the axial direction include (1) a method of controlling tension by changing the rotational speed of the rolls of a mandrel mill; (2) A method was proposed to control the rolling gap position of the finishing stand on the downstream side of the mandrel mill. However, the method (1) described above is ineffective because it cannot control the tension between adjacent stands for the material between one stand on the downstream end of the shell, and the method (2) does not control the rolling down. It is necessary to increase the rigidity of the mandrel mill of the stand used, which increases the size of the mandrel mill and increases its cost. In addition, it has the disadvantage that rapid control cannot be performed due to the responsiveness of the rolling down system such as a hydraulic cylinder. The present invention has been proposed in order to eliminate the above-mentioned drawbacks, and provides a mandrel rolling method for seamless steel pipes that can easily control the wall thickness of the raw pipe between one stand on the downstream end of the shell at low cost. The purpose is to provide. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments with reference to the drawings. The present invention inserts a mandrel bar into a hollow tube,
When reducing the thickness of a hollow tube using a full-float mandrel mill, the length on the upstream side equal to the distance from the entrance side stand of the mandrel mill to the final wall thickness determination stand is defined as the regular diameter. This is a mandrel mill rolling direction for seamless steel pipes, which is characterized in that a hollow shell is continuously rolled using a mandrel bar whose diameter on the downstream end side is reduced by a size commensurate with the amount of spring back. As shown in FIG. 2, the mandrel mill 1 has upper and lower rolls 2, 2, . In a mandrel mill, the final wall thickness of the pipe is usually determined by the specifications of the steel pipe to be manufactured. Therefore, the distance from the entrance side stand of the mandrel mill to the final wall thickness determination stand is a value specific to the type of mandrel mill and steel pipe. The mandrel levers 3X, 3Y, and 3Z, which are core bars used in the mandrel mill 1 to continuously roll the hollow tube 4 according to the method according to the embodiment of the present invention, are cylindrical rod-shaped as shown in FIGS. 3a, b, and c. The downstream end 3a has a protruding shape. In order to correct wall thickness fluctuations on the downstream end side of the shell, the upstream length part of the mandrel lever 3X equal to the distance from the mandrel mill inlet side stand to the final wall thickness determination stand is set in advance to the regular diameter, and then the downstream As shown in FIG. 3a, the diameter of the end portion is reduced by Δαi and stepped processing is performed so that the diameter becomes dD 1 . The amount of stepping in this case is determined by equation (1). dD−dD 1 =Δαi (1) where i is the number of the stand that determines the final wall thickness. The length to be stepped is the downstream end portion of the entire length of the mandrel bar, excluding the upstream length portion equal to the distance from the mandrel mill entrance stand to the final wall thickness determination stand. 7th
The figure shows this, and shows the state in which the tip of the hollow tube 4 has reached the final wall thickness determining stand 5b. In the mandrel bar 3, the length L from the inlet side stand 5a to the final thickness determining stand 5b is a regular diameter, and the downstream length L thereof is stepped. The diameter reduced by the step processing is a size commensurate with the amount of spring back determined by the above equation (1) depending on the pipe diameter, etc., and is, for example, 0.1 to 1.0 mm. Furthermore, since the thickness distribution on the downstream end side of the shell changes depending on the diameter of the mandrel bar, if the thickness distribution on the downstream end side of the shell is tapered, the corresponding mandrel bar 3Y as shown in FIG. If the shape of the predetermined interval is tapered and the diameter of the downstream end 3a is dD 1 , and if the wall thickness distribution is curved, then the shape of the predetermined interval of the mandrel bar 3Y is curved and downstream as shown in FIG. The diameter of the end 3a may be dD1 .
The mandrel bars 3X, 3Y, and 3Z are inserted into the hollow shell 4, and the hollow shell 4 is moved in the direction of the arrow 4a and continuously rolled by being bitten into the mandrel mill 1. At this time, a schematic diagram of the rolling state in an arbitrary stand is shown in FIG. roll 2,2
...If the area sandwiched from the outer and inner surfaces by the mandrel bars 3X, 3Y, and 3Z is the bottom part 3b, and the area not in contact with the mandrel bars 3X is the flange part 3c, the wall thickness of the hollow tube 4 is ti. is given by equation (2) in the region of the bottom portion 3b. ti = {(dki − dD) + αi)} / 2 ... (2) dD: Mandrel bar diameter αi: Spring back amount dki: Caliber bottom interval Here, the spring back amount is determined by the temperature rise ΔTs on the downstream end of rolling. αi decreases. The amount of decrease in springback Δαi is expressed as Δαi=ki・ΔTs・dD (3) using a constant ki determined by the stand number. Here, if the caliber bottom interval dki changes by Δαi, the wall thickness ti changes by Δαi/2 from equation (2). FIG. 5 shows a schematic diagram of the shell thickness distribution. Shell outer diameter 90 mm and shell wall thickness in this example method
Various values for 4.50mm are shown in Table 1. By substituting various numerical values into the above equation (2), Δαi=0.39mm was obtained. The downstream end wall thickness distribution of the shell rolled using the conventional mandrel bar 3 shown in FIG. 1 is shown in FIG. 6a.
The wall thickness distribution on the downstream end side of the shell rolled using the mandrel bar 3X, which has a diameter of 77.5 mm and is stepped at a predetermined interval l of 3.5 m on the downstream end 3a side so as to become thinner by 0.4 mm in diameter, is 6th. Shown in Figure b. According to the conventional method, the wall thickness was approximately 0.2 mm thinner than the average wall thickness, but by using the mandrel bar 3X, the wall thickness deviation was reduced to approximately 0.1 mm. As explained above, the present invention uses a mandrel bar whose downstream end diameter is smaller than the central diameter, thereby controlling the wall thickness of the hollow tube between one stand on the downstream end side of the mandrel mill at low cost. This has the advantage that it can be easily performed. 【table】
第１図は従来方法に用いられるマンドレルバー
形状説明図、第２図はマンドレルミルにおける圧
延状態説明図、第３図ａ，ｂ，ｃは本実施例方法
に用いられるマンドレルバー形状説明図、第４図
はマンドレルミル圧延の模式図、第５図はシエル
肉厚分布の模式図、第６図は従来方法と本実施例
方法によるシエルの肉厚状態説明図、第７図はマ
ンドレルミルの圧延状態の説明図である。
１……マンドレルミル、２……ロール、３，３
Ｘ，３Ｙ，３Ｚ……マンドレルバー、４……中空
素管、５ａ……入口側スタンド、５ｂ……最終肉
厚決定スタンド。
Fig. 1 is an explanatory diagram of the shape of the mandrel bar used in the conventional method, Fig. 2 is an explanatory diagram of the rolling state in the mandrel mill, and Figs. Fig. 4 is a schematic diagram of mandrel mill rolling, Fig. 5 is a schematic diagram of shell thickness distribution, Fig. 6 is an explanatory diagram of the shell thickness state by the conventional method and the method of this embodiment, and Fig. 7 is mandrel mill rolling. It is an explanatory diagram of a state. 1...Mandrel mill, 2...Roll, 3,3
X, 3Y, 3Z...Mandrel bar, 4...Hollow tube, 5a...Inlet side stand, 5b...Final wall thickness determination stand.
Claims (1)
ロート式マンドレルミルを用いて、中空素管の管
厚を減少させるに当り、該マンドレルミルの入口
側スタンドから最終肉厚決定スタンドまでの距離
に等しい上流側の長さ部分を正規の直径としそれ
より下流端側の直径をスプリングバツク量に見合
つた寸法だけ縮小したマンドレルバーを用いて中
空素管を連続圧延することを特徴とする継目無鋼
管のマンドレルミル方式圧延方法。1. When inserting a mandrel bar into a hollow tube and using a full-float mandrel mill to reduce the thickness of the hollow tube, the distance is equal to the distance from the inlet stand of the mandrel mill to the final wall thickness determination stand. A seamless steel pipe characterized in that a hollow blank pipe is continuously rolled using a mandrel bar in which the length part on the upstream side has a regular diameter and the diameter on the downstream end side is reduced by a size commensurate with the amount of spring back. Mandrel mill rolling method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6113484A JPS60206507A (en) | 1984-03-30 | 1984-03-30 | Method for rolling seamless steel pipe by mandrel mill system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6113484A JPS60206507A (en) | 1984-03-30 | 1984-03-30 | Method for rolling seamless steel pipe by mandrel mill system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60206507A JPS60206507A (en) | 1985-10-18 |
| JPH0534084B2 true JPH0534084B2 (en) | 1993-05-21 |
Family
ID=13162303
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6113484A Granted JPS60206507A (en) | 1984-03-30 | 1984-03-30 | Method for rolling seamless steel pipe by mandrel mill system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60206507A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2924523B2 (en) * | 1992-12-11 | 1999-07-26 | 住友金属工業株式会社 | Elongation rolling method of metal tube by mandrel mill |
| CN102489516A (en) * | 2011-11-29 | 2012-06-13 | 洛阳璋泰非标机械有限公司 | Process and equipment for hot rolling extra-small diameter seamless steel pipe with fixed mandrel |
| CN106391713B (en) * | 2016-10-31 | 2019-03-12 | 太原科技大学 | A kind of mandrel rolling method of metal pipe material |
| CN111203444B (en) * | 2020-01-07 | 2024-05-07 | 大冶特殊钢有限公司 | Core rod for producing thin-wall seamless pipe |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5343066A (en) * | 1976-09-29 | 1978-04-18 | Antoreebuichi Shi Arekusandoru | Continuous pipe rolling and rolling mill |
-
1984
- 1984-03-30 JP JP6113484A patent/JPS60206507A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5343066A (en) * | 1976-09-29 | 1978-04-18 | Antoreebuichi Shi Arekusandoru | Continuous pipe rolling and rolling mill |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60206507A (en) | 1985-10-18 |
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