US20080047317A1 - Method of manufacturing a seamless steel tube - Google Patents

Method of manufacturing a seamless steel tube Download PDF

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Publication number
US20080047317A1
US20080047317A1 US11/889,609 US88960907A US2008047317A1 US 20080047317 A1 US20080047317 A1 US 20080047317A1 US 88960907 A US88960907 A US 88960907A US 2008047317 A1 US2008047317 A1 US 2008047317A1
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US
United States
Prior art keywords
speed
rolled
mandrel
mandrel bar
bar
Prior art date
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Abandoned
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US11/889,609
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English (en)
Inventor
Kenichi Sasaki
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Nippon Steel Corp
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Individual
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Filing date
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Assigned to SUMITOMO METAL INDUSTRIES, LTD. reassignment SUMITOMO METAL INDUSTRIES, LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SASAKI, KENICHI
Publication of US20080047317A1 publication Critical patent/US20080047317A1/en
Abandoned legal-status Critical Current

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    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/78—Control of tube rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B2275/00—Mill drive parameters
    • B21B2275/02—Speed
    • B21B2275/06—Product speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
    • B21B3/02—Rolling special iron alloys, e.g. stainless steel

Definitions

  • This invention relates to a method of manufacturing a seamless steel tube or pipe (hereinafter merely referred to as tube) containing at least 5% of Cr (in this description, unless otherwise specified, “%” means “mass %”).
  • the present invention relates to a method of manufacturing a seamless steel tube which effectively prevents mandrel bar withdrawal troubles after elongation rolling of a material being rolled which is made of a high alloy steel containing at least 5% of Cr.
  • a raw material in the form of a round billet or a square billet is introduced into a rotary hearth furnace and heated therein to 1200-1260° C.
  • the raw material is then pierced with a piercer to form a hollow mother tube.
  • a mandrel bar is then inserted into the bore of the hollow mother tube until it extends beyond the bore, and the mother tube is subjected to elongation rolling using a mandrel mill normally including 5 to 8 stands while gripping the outer surface of the hollow mother tube with grooved rolls, thereby reducing the wall thickness of the mother tube to a predetermined value.
  • the mother tube is subjected to rolling for sizing to a predetermined outer diameter using a reducing mill to manufacture a seamless steel tube.
  • Mandrel mills for elongation rolling are classified into full floating mandrel mills which do not constrain the movement of the mandrel bar in the axial direction, and retained mandrel mills in which the speed of movement (retained speed) of the mandrel bar in the axial direction is maintained constant by holding the rear end of the mandrel bar with a bar retainer installed on the inlet side of the mandrel mill.
  • the speed of movement the mandrel bar unavoidably varies, which tends to result in variations in the dimensions of the resulting mother tube. Therefore, in recent years, retained mandrel mills have been widely used in elongation rolling.
  • Patent Document 1 discloses an invention in which elongation rolling is performed using a retained mandrel mill for which the speed of movement of the mandrel bar is set at a value of at least 0.25 times the rolling speed at the entrance of each roll stand and at most 1.5 times the rolling speed at the exit thereof, thereby improving the quality of the inner surface of the material being rolled.
  • Patent Document 1 JP H08-294711 A1
  • the present inventors found that if a hollow mother tube of a high alloy steel containing at least 5% of Cr is subjected to elongation rolling using a retained mandrel mill based on the invention disclosed in Patent Document 1, a phenomenon in which it becomes difficult to withdraw the mandrel bar from the material being rolled after the completion of elongation rolling (in this description, this phenomenon will be referred to as a “mandrel bar withdrawal trouble”) occurs.
  • Mandrel bar withdrawal troubles are a cause of a marked decrease in productivity of elongation rolling using a retained mandrel mill. Therefore, it is an extremely important technical problem which must be solved in order to mass produce seamless steel tube of a high alloy steel containing at least 5% of Cr on an industrial scale.
  • the present invention is a method of manufacturing a seamless steel tube characterized in that a seamless steel tube of a high alloy steel containing at least 5% of Cr is manufactured by a process comprising subjecting a material being rolled to elongation rolling using a retained mandrel mill having a constant speed of movement of a mandrel bar in the axial direction in such a manner that the speed Vb of the mandrel bar, the speed Vi of the material being rolled on the inlet side of the retained mandrel mill, and the speed Ve of the material being rolled on the exit side of the retained mandrel mill satisfy the relationship: 0.15 ⁇ Vb/ ⁇ ( Vi+Ve )/2 ⁇ 0.70.
  • the above-described relationship is preferably satisfied by controlling the value of at least one of the speed Vb of the mandrel bar, the speed Vi of the material being rolled on the inlet side of the retained mandrel mill, and the speed Ve of the material being rolled on the exit side of the retained mandrel mill.
  • FIGS. 1 ( a )- 1 ( d ) are explanatory views showing the behavior over time of a mandrel bar and a material being rolled in a retained mandrel mill having 5 stands.
  • FIG. 2 is a graph showing the relationship between the rate of overlap K with the rate of occurrence of rolling troubles ⁇ (number of occurrences of rolling troubles/number of members being rolled) ⁇ 100 ⁇ or with the surface roughness Ra of a mandrel bar after it has been used for rolling of 50 members when a seamless steel tube was manufactured by carrying out elongation rolling of a material being rolled made of 13% Cr steel while varying the rate of overlap K in the range of 0.1 to 0.8.
  • a raw material in the form of a round billet or a square billet made of a high alloy steel containing at least 5% of Cr is introduced into a rotary hearth furnace and heated therein to 1200-1260° C.
  • the raw material is then removed from the heating furnace, and it is subjected to piercing with a piercer to form a hollow mother tube.
  • the formation of the hollow mother tube can be performed in a conventional manner. Such a method is known to those skilled in the art, and a further explanation of this step will be omitted.
  • a mandrel bar is inserted into the bore of the hollow mother tube until it extends beyond the bore, and the wall thickness of the hollow mother tube is reduced to a predetermined value by subjecting the hollow mother tube to elongation rolling using a retained mandrel mill normally comprising 5 to 8 stands (5 stands in this embodiment) while gripping the outer surface of the hollow mother tube with grooved rolls in each stand.
  • a bar retainer (not shown) for holding the rear end of the mandrel bar is installed on the inlet side of the retained mandrel mill for elongation rolling. During elongation rolling, the rear end of the mandrel bar is held by this bar retainer. As a result, the speed of movement Vb of the mandrel bar in the axial direction is maintained constant during elongation rolling.
  • elongation rolling is carried out on a material being rolled such that the speed of movement Vb of the mandrel bar, the speed Vi of the material being rolled on the inlet side of the retained mandrel mill, and the speed Ve of the material being rolled on the exit side of the retained mandrel mill during elongation rolling satisfy the following relationship: 0.15 ⁇ Vb / ⁇ ( Vi+Ve )/2 ⁇ 0.70. The reason why elongation rolling is carried out while satisfying this relationship will be explained below.
  • the present inventors found that if the retained speed of movement Vb of the mandrel bar, the speed Vi of the material being rolled on the inlet side of the retained mandrel mill, and the speed Ve of the material being rolled on the exit side of the retained mandrel mill satisfy certain conditions during elongation rolling, the length of the region of the material being rolled after the completion of elongation rolling (the material being rolled at this stage also being referred to as a “shell” in this description) contacting the mandrel bar (this region referred to in this description as the “overlapping region”) can be set at a suitable dimension, thereby making it possible to effectively prevent mandrel bar withdrawal troubles and minimize a decrease in the service life of the mandrel bar.
  • FIGS. 1 ( a )- 1 ( d ) are explanatory views showing the behavior over time of a mandrel bar 2 and a material being rolled 3 in a retained mandrel mill 1 which includes 5 stands ( 1 std- 5 std).
  • the bar retainer which is provided for holding the rear end 2 a of the mandrel bar 2 has been omitted from FIG. 1 .
  • the material being rolled 3 prior to elongation rolling using the retained mandrel mill 1 (the material being rolled at this stage also referred to below as the “mother tube”) has a length Si.
  • the material being rolled 3 after elongation rolling using the retained mandrel mill 1 (the shell) has a length Se.
  • the speed of the material being rolled 3 on the inlet side of the retained mandrel mill 1 is Vi
  • the speed of the material being rolled 3 on the exit side of the retained mandrel mill 1 is Ve
  • the speed of movement of the mandrel bar 2 is Vb.
  • the average rolling speed of the retained mandrel mill 1 in the time from the state shown in FIG. 1 ( c ) in which the leading front end of the material being rolled 3 has just been gripped by the grooved rolls of the fifth stand 5 std to the state shown in FIG. 1 ( d ) in which the rear end of the material being rolled 3 has passed through the grooved rolls of the fifth stand 5 std is (Vi+Ve)/2.
  • the length of rolling time from the state shown in FIG. 1 ( c ) to the state shown in FIG. 1 ( d ) is Se/ ⁇ (Vi+Ve)/2 ⁇ .
  • the mandrel bar 2 tends to suffer from wear, surface roughening, or even cracking or galling to the shell 3 , and the service life of the mandrel bar 2 decreases.
  • the rate of overlap K is inversely proportional to the average rolling speed in the retained mandrel mill 1 . Therefore, if the rate of overlap K becomes too small due to making the difference in speed between the average rolling speed and the speed of movement of the mandrel bar 2 large, friction between the mandrel bar 2 and the material being rolled 3 becomes large. As a result, it becomes easy for wear, surface roughening, and similar problems to occur in the mandrel bar 2 .
  • the rate of overlap K there exist a preferred upper limit in order to achieve ease of withdrawal of the mandrel bar 2 and a preferred lower limit in order to suppress a decrease in the service life of the mandrel bar 2 .
  • rolling troubles means troubles in withdrawing a mandrel bar from a material being rolled.
  • the upper limit on the rate of overlap K is preferably 0.60 and more preferably 0.50.
  • the lower limit on the rate of overlap K is preferably 0.2 and more preferably 0.3.
  • the rate of overlap K can be made to be in the range of at least 0.15 to at most 0.70 by controlling the value of at least one of the speed of movement Vb of the mandrel bar 2 which is held at its rear end by the bar retainer of the retained mandrel mill 1 , the speed Vi of the material being rolled 3 on the inlet side of the retained mandrel mill 1 , and the speed Ve of the material being rolled 3 on the exit side of the retained mandrel mill 1 .
  • the simplest way to control the rate of overlap K to be in the range of at least 0.15 to at most 0.70 is to maintain the values of the speed Vi of the material being rolled 3 , the rate of elongation, and the speed Ve of the material being rolled 3 constant and to suitably vary the speed of movement Vb of the mandrel bar 2 , as described in Examples 1 and 2 given below.
  • a mandrel bar 2 is withdrawn from a material being rolled 3 which has a decreased wall thickness by elongation rolling performed in this manner.
  • elongation rolling is carried out with the rate of overlap K made at least 0.15 to at most 0.70 by controlling the value of at least one of the speed of movement Vb of the mandrel bar 2 , the speed Vi of the material being rolled 3 , and the speed Ve of the material being rolled 3 , withdrawal troubles of the mandrel bar 2 occurring after elongation rolling of the material being rolled 3 can be effectively suppressed, and the occurrence of damage to the mandrel bar can be suppressed, thereby achieving an extended service life of the mandrel bar.
  • the material being rolled 3 from which the mandrel bar 2 has been withdrawn without occurrence of withdrawal troubles is then subjected to sizing into a predetermined outer diameter using a reducing mill.
  • a seamless steel tube of a high alloy steel containing at least 5% of Cr can be reliably mass produced on an industrial scale.
  • a mother tube measuring 350 mm in outer diameter, 27.55 mm in wall thickness, and 9849 mm in length and having a steel composition containing 13% Cr and 6% Ni was subjected to elongation rolling using a retained mandrel mill to obtain a shell having an outer diameter of 295 mm, a wall thickness of 12.55 mm, and a length of 24685 mm.
  • the speed Vi (mm/second) of the mother tube, the rate of elongation EL, and the speed Ve (mm/second) of the shell were set to constant values for each condition in Table 1, and the speed of movement Vb of the mandrel bar was varied in the range of 500-2600 mm/second.
  • Those runs having a rate of overlap K of at least 0.15 to at most 0.70 were examples of this invention, and those outside of this range were comparative examples.
  • the “ease of withdrawal” in Table 1 is indicated by “O” when the rate of occurrence of rolling troubles was less than 0.1%, it is indicated by “ ⁇ ” when the rate of occurrence of rolling troubles was at least 0.1% to at most 1.0%, and it is indicated by “X” when the rate of occurrence of rolling troubles exceeded 1%.
  • the “bar damage” in Table 1 is indicated by “O” when the surface roughness Ra of the mandrel bar after elongation rolling of 50 members using the same mandrel bar was less than 3 ⁇ m, it is indicated by “ ⁇ ” when it was at least 3 ⁇ m to at most 7 ⁇ m, and it is indicated by X when it exceeded 7 ⁇ m.
  • a mother tube measuring 337 mm in outer diameter, 41.03 mm in wall thickness, and 5473 mm in length and having a steel composition containing 18% Cr and 8% Ni was subjected to elongation rolling using a retained mandrel mill to obtain a shell with an outer diameter of 295 mm, a wall thickness of 31.03 mm, and a length of 8115 mm.
  • Table 2 shows the values of the same parameters as those set forth in above-described Table 1.
  • the speed Vi (mm/second) of the mother tube, the rate of elongation EL, and the speed Ve of the shell (mm/second) were set to the constant values as shown in Table 2 for each condition, but in contrast to Example 1, the speed of movement Vb of the mandrel bar was varied in the range of 250-1400 mm.
  • the test results are compiled in Table 2.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Metal Rolling (AREA)
  • Heat Treatment Of Steel (AREA)
  • Metal Rolling (AREA)
  • Metal Extraction Processes (AREA)
  • Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)
US11/889,609 2005-02-16 2007-08-15 Method of manufacturing a seamless steel tube Abandoned US20080047317A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2005-038689 2005-02-16
JP2005038689 2005-02-16
JPPCT/JP06/02769 2006-02-16

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
JPPCT/JP06/02769 Continuation 2005-02-16 2006-02-16

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US20080047317A1 true US20080047317A1 (en) 2008-02-28

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US11/889,609 Abandoned US20080047317A1 (en) 2005-02-16 2007-08-15 Method of manufacturing a seamless steel tube

Country Status (9)

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US (1) US20080047317A1 (ru)
EP (1) EP1878514A4 (ru)
CN (1) CN101160184B (ru)
BR (1) BRPI0608086A2 (ru)
CA (1) CA2598297A1 (ru)
MX (1) MX2007009772A (ru)
RU (1) RU2357814C1 (ru)
WO (1) WO2006088107A1 (ru)
ZA (1) ZA200707262B (ru)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090071221A1 (en) * 2006-03-28 2009-03-19 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

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BR112015000206A2 (pt) 2012-07-24 2017-06-27 Nippon Steel & Sumitomo Metal Corp método de fabricação de tubulação de metal sem emendas, fresa de mandril e ferramenta auxiliar
JP6171851B2 (ja) 2013-10-29 2017-08-02 Ｊｆｅスチール株式会社 継目無鋼管製造用装置列およびそれを利用した油井用高強度ステンレス継目無鋼管の製造方法
RU2713531C1 (ru) * 2019-04-08 2020-02-05 Публичное акционерное общество "Трубная металлургическая компания" (ПАО "ТМК") Способ непрерывной прокатки труб
RU2751069C1 (ru) * 2020-09-30 2021-07-07 Публичное акционерное общество "Трубная металлургическая компания" (ПАО "ТМК") Способ производства бесшовных труб из нержавеющей стали мартенситного класса типа 13Cr

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3392565A (en) * 1965-02-15 1968-07-16 Blaw Knox Co Manufacture of seamless tubing
US4091650A (en) * 1976-01-19 1978-05-30 Vallourec (Usines A Tubes De Lorraine-Escaut Et Vallourec Reunies) Rolling mill for forming seamless tubes, and seamless tube-making apparatus comprising such a mill
US4353238A (en) * 1981-05-18 1982-10-12 Vallourec, Societe Anonyme Method for manufacture of seamless metal tubing by continuous rolling

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5853320A (ja) * 1981-09-24 1983-03-29 Toshiba Corp マンドレルミルにおける管状の材料の肉厚制御方法
JPS61108409A (ja) * 1984-11-01 1986-05-27 Kawasaki Steel Corp マンドレルミル圧延方法
JP2924523B2 (ja) * 1992-12-11 1999-07-26 住友金属工業株式会社 マンドレルミルによる金属管の延伸圧延方法
JPH08300013A (ja) * 1995-04-27 1996-11-19 Sumitomo Metal Ind Ltd マンドレルミルにおけるバーストリッピング方法
JP2004330226A (ja) * 2003-05-02 2004-11-25 Sumitomo Metal Ind Ltd 継目無し鋼管の製造方法

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3392565A (en) * 1965-02-15 1968-07-16 Blaw Knox Co Manufacture of seamless tubing
US4091650A (en) * 1976-01-19 1978-05-30 Vallourec (Usines A Tubes De Lorraine-Escaut Et Vallourec Reunies) Rolling mill for forming seamless tubes, and seamless tube-making apparatus comprising such a mill
US4353238A (en) * 1981-05-18 1982-10-12 Vallourec, Societe Anonyme Method for manufacture of seamless metal tubing by continuous rolling

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090071221A1 (en) * 2006-03-28 2009-03-19 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
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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Publication number Publication date
BRPI0608086A2 (pt) 2009-11-10
MX2007009772A (es) 2008-03-10
RU2357814C1 (ru) 2009-06-10
EP1878514A1 (en) 2008-01-16
WO2006088107A1 (ja) 2006-08-24
CA2598297A1 (en) 2006-08-24
CN101160184A (zh) 2008-04-09
EP1878514A4 (en) 2009-01-07
ZA200707262B (en) 2008-09-25
RU2007134439A (ru) 2009-03-27
CN101160184B (zh) 2011-09-28

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