Method for manufacturing seamless pipe

• US 5,778,714 A
• Filed: 05/13/1996
• Issued: 07/14/1998
• Est. Priority Date: 05/19/1995
• Status: Expired due to Term

• Current Assignee: NKK Tubes (NKKTubes KK)
• Original Assignee: NKK Corporation (JFE Holdings Incorporated)
• Inventors: Yamazaki, Motoharu, Yasukawa, Masahiko, Ariizumi, Takashi, Katsumura, Tatsuro
• Primary Examiner(s): Larson, Lowell A.
• Assistant Examiner(s): BUTLER, RODNEY ALLEN
• Application Number:
  US08/645,223
• Time in Patent Office: 792 Days
• Field of Search: 72/97, 72/208, 72/209, 72/367, 72/368, 72/370, 72/43, 72/42
• US Class Current: 72/97
• CPC Class Codes: B21B 17/08 with mandrel having one or more protrusions , i.e. only the mandrel plugs contact the rolled tube; Press-piercing mills
• CPC Class Codes: B21B 19/04 Rolling basic material of solid, i.e. non-hollow, structure; Piercing , e.g. rotary piercing mills
• CPC Class Codes: B21B 25/00 Mandrels for metal tube rolling mills, e.g. mandrels of the types used in the methods covered by group B21B17/00; Accessories or auxiliary means therefor ; Construction of, or alloys for, mandrels or plugs
• CPC Class Codes: B21B 25/04 Cooling or lubricating mandrels during operation
• CPC Class Codes: B21B 3/02 Rolling special iron alloys , e.g. stainless steel
• CPC Class Codes: Y10T 29/4981 Utilizing transitory attached element or associated separate material

Abstract

A method for manufacturing a seamless pipe, comprises:

preparing a billet made of an alloy steel or an alloy;

joining a steel plate to an end surface at which piercing of the billet is commenced;

preparing a piercing plug made of Mo, a Mo alloy or a heat-resisting steel;

hot-piercing the billet by using the piercing plug to produce a hollow shell; and

rolling the hollow shell to produce a seamless pipe.

Claims

1. A method for manufacturing a seamless pipe, comprising the steps of:

(a) preparing a billet made of an alloy steel or an alloy having a main component selected from the group consisting of Cr, Ni and Mo;

(b) joining a steel plate at least to an end surface of the billet at which a piercing of the billet is to be commenced;

(c) preparing a piercing plug, the piercinc plug comprising (i) a main body made of Mo, a Mo alloy or a heat resisting steel and (ii) a hard laver formed on the surface of the main body, wherein said hard layer is made of any one selected from the group consisting of stellite, a ceramic obtained by adding tungsten carbide to stellite, a ceramic obtained by adding a mixture composition of tungsten carbide and cobalt to stellite and a ceramic obtained by adding a compound of chromium and carbon to stellite;

(d) hot-piercing the billet at a hot-piercing temperature, to which the steel plate is Joined, with the piercing plug by a Mannesmann piercing to produce a hollow shell, an oxide scale being formed from said steel plate, at the hot-piercing temperature, the oxide scale lubricating the piercing plug during the hot-piercing; and

(e) rolling the hollow shell to produce a seamless pipe.

2. The method of claim 1, wherein said billet comprises an alloy steel containing Cr in an amount of at least 5 wt %.

3. The method of claim 1, wherein said billet comprises an alloy steel containing Ni in an amount of at least 5 wt %.

4. A method for manufacturing a seamless pipe, comprising the steps of:

(a) preparing a billet made of an alloy steel or an alloy having a main component selected from the group consisting of Cr, Ni and Mo;

(b) joining a steel plate at least to an end surface of the billet at which a piercing of the billet is to be commenced;

(c) preparing a piercing plug, the piercing plug comprising (i) a plug body made of Mo, a Mo alloy or a heat-resisting steel and (ii) a plug head formed at a leading end of the plug body, the plug head being made of Mo, a Mo alloy or a heat resisting steel, the plug body having a hard layer formed on a surface of the plug body, wherein said hard layer is made of any one selected from the group consisting of stellite, a ceramic obtained by adding tungsten carbide to stellite, a ceramic obtained by adding a mixture composition of tungsten carbide and cobalt to stellite and a ceramic obtained by adding a compound of chromium and carbon to stellite;

(d) hot-piercing the billet at a hot-piercing temperature, to which the steel plate is joined, with the piercing plug by a Mannesmann piercing to produce a hollow shell, an oxide scale being formed from said steel plate, at the hot-piercing temperature, the oxide scale lubricating the piercing plug during the hot-piercing; and

(e) rolling the hollow shell to produce a seamless pipe.

5. A method for manufacturing a seamless pipe, comprising the steps of:

(a) preparing a billet made of an allov steel or an alloy having a main component selected from the group consisting of Cr, Ni and Mo;

(b) joining a steel plate at least to an end surface of the billet at which a piercing of the billet is to be commenced;

(c) preparing a piercing slug, the piercing plug comprising (i) a plug body made of Mo, a Mo alloy or a heat-resisting steel and (ii) a plug head formed at a leading end of the plug body, the plug head being made of Mo, a Mo alloy or a heat resisting steel, the plug head having a hard layer formed on a surface of the plug head, wherein said hard layer is made of any one selected from the group consisting of stellite, a ceramic obtained by adding tungsten carbide to stellite, a ceramic obtained by adding a mixture composition of tungsten carbide and cobalt to stellite and a ceramic obtained by adding a compound of chromium and carbon to stellite;

(d) hot-piercing the billet at a hot-piercing temperature, to which the steel plate is joined, with the piercing plug by a Mannesmann piercing to produce a hollow shell, an oxide scale being formed from said steel plate, at the hot-piercing temperature, the oxide scale lubricating the piercing plug during the hot-piercing; and

(e) rolling the hollow shell to produce a seamless pipe.

6. A method for manufacturing a seamless pipe, comprising the steps of:

preparing a billet made of an alloy steel or an alloy having a main component selected from the group consisting of Cr, Ni and Mo;

joining a steel plate at least to an end surface of the billet at which a piercing of the billet is to be commenced, the steel plate being subjected to an oxidation treatment;

heating the billet to which the steel plate is joined;

hot-piercing the heated billet at a hot-piercing temperature with a piercing plug by a Mannesmann piercing to produce a hollow shell;

an oxide scale being formed from said steel plate, at the hot-piercing temperature, the oxide scale lubricates the piercing plug during the hot-piercing; and

rolling the hollow shell to produce a seamless pipe.

7. The method of claim 6, wherein said billet comprises an alloy steel containing Cr in an amount of at least 5 wt %.

8. The method of claim 6, wherein said billet comprises an alloy steel containing Ni in an amount of at least 5 wt %.

9. The method of claim 6, wherein said steel plate comprises a carbon steel.

10. The method of claim 6, wherein said steel plate comprises an alloy steel containing one element selected from the group consisting of C in an amount of less than 5 wt %, Cr in an amount of less than 5 wt % and Ni in an amount of less than 5 wt %.

11. The method of claim 6, wherein said steel plate comprises an alloy steel containing Si in an amount of 1 wt % or more.

12. The method of claim 6, wherein the joining of the steel plate is carried out by welding.

13. A method for manufacturing a seamless pipe, comprising the steps of:

preparing a billet made of an alloy steel or an alloy having a main component selected from the group consisting of Cr, Ni and Mo;

heating the billet in a heating furnace;

joining a steel plate at least to an end surface of the billet at which a piercing of the billet is to be commenced, the steel plate being subjected to an oxidation treatment;

hot-piercing the heated billet at a hot-piercing temperature, to which the steel plate is joined, with a piercing plug by a Mannesmann piercing to produce a hollow shell;

an oxide scale being formed from said steel plate, at the hot-piercing temperature, the oxide scale lubricates the piercing plug during hot-piercing; and

rolling the hollow shell to produce a seamless pipe.

14. The method of claim 13, wherein said billet comprises an alloy steel containing Cr in an amount of at least 5 wt %.

15. The method of claim 13, wherein said billet comprises an alloy steel containing Ni in an amount of at least 5 wt %.

16. The method of claim 13, wherein said steel plate comprises a carbon steel.

17. The method of claim 13, wherein said steel plate comprises an alloy steel containing one element selected from the group consisting of C in an amount of less than 5 wt %, Cr in an amount of less than 5 wt % and Ni in an amount of less than 5 wt %.

18. The method of claim 13, wherein said steel plate comprises an alloy steel containing Si in an amount of 1 wt % or more.

19. The method of claim 13, wherein the joining of the steel plate is carried out by forcible joining.

20. A method for manufacturing a seamless pipe, comprising the steps of:

preparing a billet made of a high alloy steel or a high alloy;

preparing a piercing plug having a plug rolling portion and a plug reeling portion, the plug reeling portion is adjacent to the plug rolling portion, the piercing plug satisfies the following equation;

0.80°

≦

α

-β

≦

1.51°

, wherein α

is an angle of the plug reeling portion and β

is an angle at an outlet portion of a piercing roll;

hot-piercing the billet with the piercing plug to produce a hollow shell; and

rolling the hollow shell to produce a seamless pipe.

21. The method of claim 20, further comprising the step of joining a steel plate at least to an end surface at which piercing of the billet is commenced, wherein the piercing is carried out by a Mannesmann piercing and an oxide scale is formed from the steel plate, at a hot-piercing temperature, the oxide scale lubricates the plug during the hot-piercing.

22. The method of claim 20, wherein the high alloy is an alloy having a main component selected from the group consisting of Cr, Ni and Mo.