Title:
継目無鋼管の製造方法
Document Type and Number:
Japanese Patent JP4305673
Kind Code:
B2
Abstract:
A process for producing a seamless steel pipe, in which the occurrence of inner surface flaws in the pipe can be reduced through the lowering of the friction coefficient during the elongation rolling by means of a mandrel mill is provided. During the elongation rolling of a hollow stock pipe, a lubricant composed mainly of either or both of graphite and mica is coated to the surface of a mandrel bar, and further a lubricant composed mainly of an alkali metal borate is applied onto the inner surface of the hollow stock pipe, and also satisfies the following requirements (a) to (d):
(a) the temperature of inner surface of stock pipe immediately after the completion of piercing being set for not lower than 1150°C, and the time from the completion of piercing to the initiation of applying the lubricant composed mainly of an alkali metal borate, or the time from the completion of descaling to the initiation of applying the lubricant composed mainly of an alkali metal borate is set for 5 to 60 seconds,
(b) the temperature of inner surface of stock pipe during applying the lubricant composed mainly of an alkali metal borate being set for not lower than 1100°C,
(c) the time from the completion of applying the lubricant composed mainly of an alkali metal borate to the initiation of elongation rolling being set for not less than 10 seconds,
(d) the temperature of inner surface of stock pipe immediately before the elongation rolling being set within a range from 1000 to 1170°C.
Inventors:
Junsei Iida
Tetsuya Nakanishi
Tetsuya Nakanishi
Application Number:
JP2006514756A
Publication Date:
July 29, 2009
Filing Date:
June 15, 2005
Export Citation:
Assignee:
SUMITOMO METAL INDUSTRIES,LTD.
International Classes:
B21B25/04; B21B17/02; B21B17/04; B21B19/04; B21B45/04
Domestic Patent References:
JP2000042609A | ||||
JP2000246312A |
Attorney, Agent or Firm:
Mikiji Sugioka
Terutada Hogami
Chihara
Terutada Hogami
Chihara
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