JPH06339709A - Production of piercing mandrel for rolling seamless steel tube - Google Patents
Production of piercing mandrel for rolling seamless steel tubeInfo
- Publication number
- JPH06339709A JPH06339709A JP12973493A JP12973493A JPH06339709A JP H06339709 A JPH06339709 A JP H06339709A JP 12973493 A JP12973493 A JP 12973493A JP 12973493 A JP12973493 A JP 12973493A JP H06339709 A JPH06339709 A JP H06339709A
- Authority
- JP
- Japan
- Prior art keywords
- mandrel
- rolling
- seamless steel
- wear
- melting point
- 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.)
- Withdrawn
Links
Landscapes
- Heat Treatment Of Articles (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は丸または角型断面の素材
から継目無鋼管を製造する場合に使用される継目無鋼管
圧延用穿孔芯金（マンドレル）の製造法に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a perforated core bar (mandrel) for rolling a seamless steel pipe, which is used when producing a seamless steel pipe from a material having a round or square cross section.
【０００２】[0002]
【従来の技術】継目無鋼管を製造する主要圧延方式のプ
ラグミル方式やマンドレル方式では、鋼片を穿孔するた
めにマンドレルバーが使用されるが、そのマンドレルバ
ーは、例えば「鉄鋼便覧，第３版，第 III巻（２），条
鋼・鋼管・圧延共通設備，９７８頁，丸善（株）発行」
にも紹介されるように、Ｃｒ−Ｍｏ系およびＣｒ−Ｍｏ
−Ｖ系の材質で溶接あるいは一体物に製作された後、先
後端部分と外径を加工し、表面研摩し、しかる後目的の
硬度に仕上げる焼入れ焼戻しの調質熱処理を施して製造
されている。その耐用寿命は、被圧延材とマンドレルバ
ーとの間で、生成したスケールあるいは塗布された潤滑
剤によって摩擦条件の程度によって異なるが、通常の使
用条件下では、表面の磨耗によって減少する直径の大き
さで決定される。2. Description of the Related Art A mandrel bar is used to pierce a steel slab in a main milling method such as a plug mill method or a mandrel method for producing a seamless steel pipe. The mandrel bar is, for example, "Steel Manual, 3rd Edition". , Volume III (2), Common equipment for bar steel, steel pipes and rolling, page 978, published by Maruzen Co., Ltd. "
As also introduced in, Cr-Mo system and Cr-Mo
-V type material is welded or made into one piece, and then processed by processing the front and rear end parts and outer diameter, surface polishing, and then subjecting to temper heat treatment of quenching and tempering to finish to the desired hardness. . Its useful life depends on the degree of friction between the material to be rolled and the mandrel bar, depending on the scale produced or the lubricant applied, but under normal conditions of use, the diameter decreases as a result of surface wear. It is decided by
【０００３】一般にマンドレルバーの表面部は、継目無
鋼管圧延時常に高温度の被圧延材と接触状態にあるため
数百度の高温度に達し、寿命を著しく低下する問題か
ら、圧延終了後直ちに水冷して１００℃以下の温度に冷
却する寿命延長処置が採られている。しかしながら、こ
のような過熱と冷却の繰り返しを受けたマンドレルバー
の表面は次第に磨耗と肌荒れで径小化が進行し、その結
果寿命を律速せしめる問題があった。一般的には、マン
ドレルバーの磨耗に起因する耐用寿命の圧延可能本数は
凡そ１０００本程度、また肌荒れに起因する耐用寿命の
圧延可能本数は５０〜数１００本程度である。Generally, the surface portion of the mandrel bar is in contact with a material to be rolled at a high temperature during seamless steel pipe rolling, and reaches a high temperature of several hundreds of degrees, which considerably shortens the life. Then, a life extension treatment of cooling to a temperature of 100 ° C. or less is adopted. However, the surface of the mandrel bar that has been repeatedly heated and cooled in this manner gradually wears and roughens the surface of the mandrel bar, and the diameter of the mandrel bar is gradually reduced. As a result, the life of the mandrel bar is limited. In general, the number of rolls capable of rolling due to wear of the mandrel bar is about 1000, and the number of rolls having durable life resulting from rough skin is about 50 to several 100.
【０００４】[0004]
【発明が解決しようとする課題】このように、マンドレ
ルバーの耐用寿命は肌荒れに大きく影響され、寿命末期
では鋼管製品の内面品質を著しく劣化する品質上の問題
があった。これらの問題から製管圧延においては常に予
備のマンドレルを多数用意する必要があり、しかも頻繁
なマンドレルバーの取替作業によって製管圧延を中断し
単位時間当たりの製管個数を大幅に減少し製管コストを
高める問題もあった。As described above, the service life of the mandrel bar is greatly affected by rough skin, and there is a problem in quality that the inner surface quality of the steel pipe product is significantly deteriorated at the end of its life. Due to these problems, it is necessary to prepare a large number of spare mandrels at all times during pipe rolling, and the pipe rolling is interrupted due to frequent mandrel bar replacement work, which significantly reduces the number of pipes produced per unit time. There was also the problem of increasing pipe costs.
【０００５】また、継目無鋼管圧延用穿孔マンドレルの
使用条件は非常に複雑であり、要求する性質も多岐にわ
たっている。例えば、マンドレルバーに付着したスケー
ルを取って見ても、製管圧延時において一定の厚さで剥
離しない強い密着力を呈して、被圧延材とマンドレルバ
ーとの間の摩擦係数を低減する効果をなすこと、断熱効
果を奏してマンドレルの過熱を防止することが重要であ
る。Further, the conditions for using the perforated mandrel for seamless steel pipe rolling are very complicated, and the required properties are also diverse. For example, the effect of reducing the friction coefficient between the material to be rolled and the mandrel bar by exhibiting a strong adhesive force that does not peel off at a constant thickness during pipe rolling even when taking a scale attached to the mandrel bar. It is important to prevent the mandrel from overheating by providing a heat insulating effect.
【０００６】本発明はかかる点に着目したもので、スケ
ールの密着性を確保してマンドレルバーの耐用寿命を大
幅に改善したマンドレルを提供することを目的とする。The present invention focuses on such points, and an object of the present invention is to provide a mandrel in which the adhesion of the scale is ensured and the service life of the mandrel bar is greatly improved.
【０００７】[0007]
【課題を解決するための手段】本発明者らは、マンドレ
ルに各種のスケールを付着しマンドレルバーの肌荒れと
磨耗状況について詳細に検討した結果、マンドレルの表
面層に生成した亀甲状の微小割れにＣｕなどの低融点金
属拡散層を生成させることによって強力な密着性と潤滑
能を保有するスケールが生成し、磨耗と肌荒れを抑制し
たマンドレルが得られることを知見した。[Means for Solving the Problems] As a result of detailed examination of the skin roughness and wear condition of the mandrel bar by attaching various scales to the mandrel, the present inventors found that a hexagonal microcrack formed in the surface layer of the mandrel was found. It has been found that by forming a low melting point metal diffusion layer such as Cu, a scale having strong adhesiveness and lubricating ability is generated, and a mandrel with suppressed wear and rough skin can be obtained.
【０００８】本発明はこの知見を具現化したもので、そ
の要旨は、継目無鋼管圧延用穿孔形状に成形されたマン
ドレルの磨耗表面部にＣｕ，Ｚｕ，Ａｌ金属あるいはこ
れらの合金を拡散浸透する処理を施してその表面結晶粒
界部を脆化させた後、調質熱処理するかまたは製管圧延
初期時の高温急速加熱で、該結晶粒界脆化部に微細な亀
甲状の表層微小割れを生成させる継目無鋼管圧延用穿孔
マンドレルの製造法である。The present invention embodies this knowledge, and the gist thereof is to diffuse and permeate Cu, Zu, Al metal or alloys thereof into the wear surface of a mandrel formed into a perforated shape for seamless steel pipe rolling. After surface treatment to embrittle the crystal grain boundary portion, heat treatment is performed or high temperature rapid heating at the initial stage of pipe rolling causes fine glaze-like surface microcracks in the crystal grain boundary embrittlement portion. Is a method for producing a perforated mandrel for rolling seamless steel pipe.
【０００９】以下、本発明について詳細に説明する。通
常の鋼成分組成の素材に焼なましや切削加工などの製造
工程を経て継目無鋼管圧延用穿孔形状に成形されたマン
ドレルが被圧延材と接触するマンドレルの磨耗表面部
に、低融点金属のＣｕ，Ｚｎ，Ａｌあるいはこれら金属
の合金を拡散浸透する熱処理を施してその表面結晶粒界
部を脆化させる。マンドレル表面層の微小な亀甲状割れ
は、自然発生的には長時間の繰り返し使用による熱疲労
によって生成するもので、その成長前にスケールを剥離
し、肌荒れと磨耗の増大が促進することが多い。つま
り、低融点金属またはこれらの合金は、マンドレルの表
面結晶粒界部に侵入し溶融拡散し、微小な亀甲状割れを
強制的に生成させる作用がある。また、低融点金属は原
理的に鋼より融点が低くかつ粒界脆化を伴う上記したＣ
ｕの如き成分であればよいが、ＳｎやＰｂあるいはこれ
らのＳｎ−Ｐｂの如き余りにも低融点すぎる成分は圧延
中の温度上昇で溶融金属脆化を引き起こす問題から避け
る必要がある。The present invention will be described in detail below. A mandrel formed into a perforated shape for seamless steel pipe rolling through a manufacturing process such as annealing or cutting of a material with a normal steel composition will contact the rolled material on the wear surface of the mandrel. A heat treatment for diffusing and permeating Cu, Zn, Al or an alloy of these metals is applied to embrittle the surface grain boundary portion. Minor hexagonal cracks on the mandrel surface layer are spontaneously generated by thermal fatigue caused by repeated use over a long period of time, and often peel off the scale before its growth, promoting rough skin and increased wear. . That is, the low-melting-point metal or the alloy thereof has an action of penetrating into the surface crystal grain boundary portion of the mandrel, melting and diffusing, and forcibly forming minute glaze cracks. In addition, the low melting point metal has a lower melting point than steel in principle and the above-mentioned C accompanied by grain boundary embrittlement.
Any component such as u may be used, but a component having an excessively low melting point such as Sn or Pb or these Sn—Pb must be avoided from the problem of causing molten metal embrittlement due to a temperature increase during rolling.
【００１０】さらにまた、低融点金属またはこれらの合
金をマンドレルの表面結晶粒界に拡散浸透する処理法に
ついては、例えば、細粒化組織のオーステナイト域温度
に加熱したマンドレルを溶融した低融点金属に浸漬した
りあるいは溶射したり、低融点金属の粉末を塗布したり
あるいは薄片やワイヤーを巻き付けて高周波加熱などの
熱源で低融点金属の融点以上に短時間加熱処理するな
ど、各種の方法が採用される。この場合の低融点金属が
拡散し侵入した表面結晶粒界部脆化層の深さについて
は、限定するものでないが、マンドレルに要求される特
性を劣化せしめない範囲の１０〜２０μが好ましい。Further, regarding the treatment method of diffusing and infiltrating the low melting point metal or these alloys into the surface grain boundaries of the mandrel, for example, the low melting point metal obtained by melting the mandrel heated to the austenite region temperature of the fine grain structure is used. Various methods are adopted, such as dipping or spraying, coating low melting point metal powder, or winding a thin piece or wire and performing heat treatment for a short time above the melting point of the low melting point metal with a heat source such as high frequency heating. It In this case, the depth of the surface crystal grain boundary portion embrittlement layer into which the low melting point metal has diffused and entered is not limited, but is preferably 10 to 20 μ which is a range that does not deteriorate the characteristics required for the mandrel.
【００１１】このような前処理を施して脆化質の表面結
晶粒界部をもつマンドレルは、焼入れと焼戻しの調質熱
処理を行うかあるいは製管圧延初期時の高温急速加熱に
よって、その結晶粒界脆化部に微細な亀甲状の表層微小
割れを生成してスケールの密着性を確保し、製管圧延時
の潤滑能を呈し磨耗と肌荒れを抑制したマンドレルを製
造することができる。The mandrel which has been subjected to such pretreatment and has an embrittled surface crystal grain boundary portion is subjected to a tempering heat treatment of quenching and tempering, or by a high temperature rapid heating at the initial stage of pipe rolling, the crystal grains are It is possible to produce a mandrel in which minute glaze-like surface layer microcracks are generated in the field embrittlement portion to ensure scale adhesion, exhibit lubricity during pipe rolling, and suppress wear and roughening.
【００１２】次に、本発明の実施例について説明する。
通常の製造工程を経て継目無鋼管圧延用穿孔形状の成形
されたマンドレル（Ｃｒ：５．０％、Ｍｏ：１．０％、
Ｖ：０．４％の低合金鋼）が圧延材と接触する磨耗表面
部に、各種の低融点金属粉末を塗布し各温度に加熱して
拡散浸透する処理を施し、その表面結晶粒界部分を脆化
させた後、高温製管時に１０本の初期圧延を行いその結
晶粒界脆化部に微小な亀甲状の割れを生成させてから、
本圧延（鋼管径１８０mmφ×１２ｔ）した。その時のマ
ンドレルの製造条件とその耐寿命性を表１に纏めた。Next, an embodiment of the present invention will be described.
A mandrel (Cr: 5.0%, Mo: 1.0%) formed into a perforated shape for seamless steel pipe rolling through a normal manufacturing process.
(V: 0.4% low alloy steel) is applied to the wear surface portion where the rolled material comes into contact with various low melting point metal powders, heated to each temperature and diffused and permeated. After embrittlement, after 10 initial rolling at the time of high temperature pipe making to generate minute hexagonal cracks in the grain boundary embrittlement part,
Main rolling (steel pipe diameter 180 mmφ × 12 t) The manufacturing conditions of the mandrel at that time and the life resistance thereof are summarized in Table 1.
【００１３】[0013]
【表１】 [Table 1]
【００１４】表１に明らかな如く、本発明法のマンドレ
ルバーの耐用寿命は比較法に対比して少なくとも１．５
倍以上に延びている。本発明の効果により、比較法では
しばしば発生する肌荒れ律速に基づく短寿命のケースが
なくなり、本発明法ではいずれの条件も磨耗起因の寿命
となっており、かつ同じ磨耗起因でも寿命向上が顕著で
ある。特に、１０本の鋼管を圧延後に測定した亀甲状割
れの深さが２２〜２５μであった条件のマンドレルバー
は、耐用寿命が２２００本以上と大幅に長寿命化してい
る点が注目できる。As is apparent from Table 1, the service life of the mandrel bar of the method of the present invention is at least 1.5 compared to the comparative method.
More than doubled. By the effect of the present invention, the comparative method eliminates the case of short life that often occurs due to skin roughness control, and in the method of the present invention, both conditions result in wear-induced life, and even the same wear causes a significant improvement in life. is there. In particular, it can be noted that the mandrel bar under the condition that the hexagonal crack depth measured after rolling 10 steel pipes was 22 to 25 μm has a significantly extended service life of 2200 or more.
【００１５】[0015]
【発明の効果】以上より、本発明法は、鋼管圧延用のマ
ンドレル製造時の最終熱処理前に低融点金属を添加・加
熱するという比較的簡単な技術追加でマンドレルバーの
寿命を相当に延長し得ることが明確であり、継目無鋼管
製造における製造コストの低減ならびに鋼管内面品質向
上に大きく貢献するものである。As described above, the method of the present invention considerably extends the life of the mandrel bar by adding a relatively simple technique of adding and heating a low-melting point metal before the final heat treatment at the time of manufacturing a mandrel for rolling steel pipes. It is clear that this will contribute to a reduction in manufacturing cost in seamless steel pipe manufacturing and an improvement in the inner surface quality of steel pipes.
Claims (1)
マンドレルの磨耗表面部に、Ｃｕ，Ｚｎ，Ａｌ金属ある
いはこれらの合金を拡散浸透する処理を施してその表面
結晶粒界部を脆化させた後、調質熱処理するか、または
製管圧延初期時の高温急速加熱で、該結晶粒界脆化部に
微細な亀甲状の表層微小割れを生成させることを特徴と
する継目無鋼管圧延用穿孔マンドレルの製造法。1. A wear surface portion of a mandrel formed into a perforated shape for seamless steel pipe rolling is subjected to a treatment of diffusing and penetrating Cu, Zn, Al metal or an alloy thereof to embrittle the surface grain boundary portion thereof. After that, heat treatment for tempering, or rapid high-temperature heating at the initial stage of pipe rolling, to form fine hexagonal surface microcracks in the grain boundary embrittlement portion, seamless steel pipe rolling For manufacturing perforation mandrels for drilling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12973493A JPH06339709A (en) | 1993-05-31 | 1993-05-31 | Production of piercing mandrel for rolling seamless steel tube |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12973493A JPH06339709A (en) | 1993-05-31 | 1993-05-31 | Production of piercing mandrel for rolling seamless steel tube |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06339709A true JPH06339709A (en) | 1994-12-13 |
Family
ID=15016888
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12973493A Withdrawn JPH06339709A (en) | 1993-05-31 | 1993-05-31 | Production of piercing mandrel for rolling seamless steel tube |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06339709A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007114173A1 (en) | 2006-03-28 | 2007-10-11 | Sumitomo Metal Industries, Ltd. | Mandrel bar for rolling of high alloy, method for surface treatment of the mandrel bar, method for manufacture of the mandrel bar, and method for operation of seamless steel pipe production apparatus |
-
1993
- 1993-05-31 JP JP12973493A patent/JPH06339709A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007114173A1 (en) | 2006-03-28 | 2007-10-11 | Sumitomo Metal Industries, Ltd. | Mandrel bar for rolling of high alloy, method for surface treatment of the mandrel bar, method for manufacture of the mandrel bar, and method for operation of seamless steel pipe production apparatus |
| US8065901B2 (en) | 2006-03-28 | 2011-11-29 | Sumitomo Metal Industries, Ltd. | Mandrel bar for high-alloy rolling, method for surface treating a mandrel bar, method for producing mandrel bar, and method for operating seamless pipe mill |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 20000801 |