Title:
MANUFACTURING METHOD FOR SEAMLESS PIPE
Document Type and Number:
WIPO Patent Application WO/2008/062752
Kind Code:
A1
Abstract:
In the manufacture of a seamless pipe, a piercing rolling has the following characteristics (a) to (d). (a): a plug tip drawing ratio (TDFT) is 0.04 or less, or the root (TDFT x N)0.5 of the product of TDFT and a billet rotation speed (N) is 0.4 or less; (b): the ratio (GDFT) of the roll gap (Rg) at the gorged portion of an inclined roll and a billet external diameter (Bd) satisfies the following formula (1); (c): a plug shaped to satisfy the following formula (2) is used; and (d): the billet is pushed by a pusher at least in a non-steady range, -0.01053 x EL + 0.8768 ≤ GDFT ≤ -0.01765 x EL + 0.9717 (1) -0.95 x (TDFT x N)0.5 + 1.4 ≤ L2/d2 ≤ -1.4 x (TDFT x N)0.5 + 3.15 (2) wherein TDFT = 1 - (d1/Bd), d1: the shortest distance (mm) between the rolls at the plug tip position, Bd: the billet external diameter (mm), N = (Ld/EL)/(0.5 x π x Bd x tanβ), Ld: the projected contact length (mm) from the billet biting point to the plug tip, EL: a piercing ratio, β: the angle of inclination of the roll, L2: the length (mm) of the rolling portion of the plug, and d2: the external diameter (mm) of the boundary position between the rolling portion and the reeling portion of the plug.
Inventors:
YAMAKAWA, Tomio (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 5410041, JP)
山川 富夫 (〒41 大阪府大阪市中央区北浜四丁目５番３３号 住友金属工業株式会社内 Osaka, 5410041, JP)
山川 富夫 (〒41 大阪府大阪市中央区北浜四丁目５番３３号 住友金属工業株式会社内 Osaka, 5410041, JP)
Application Number:
JP2007/072377
Publication Date:
May 29, 2008
Filing Date:
November 19, 2007
Export Citation:
Assignee:
SUMITOMO METAL INDUSTRIES, LTD. (5-33, Kitahama 4-chome Chuo-ku, Osaka-sh, Osaka 41, 5410041, JP)
住友金属工業株式会社 (〒41 大阪府大阪市中央区北浜四丁目５番３３号 Osaka, 5410041, JP)
YAMAKAWA, Tomio (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 5410041, JP)
住友金属工業株式会社 (〒41 大阪府大阪市中央区北浜四丁目５番３３号 Osaka, 5410041, JP)
YAMAKAWA, Tomio (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 5410041, JP)
International Classes:
B21B19/04; B21B23/00; B21B25/00; B21B19/00; B21B23/00; B21B25/00
Attorney, Agent or Firm:
SUGIOKA, Kanji et al. (K. Sugioka Patent Office, 5-17-23 Higashinaniwa-cho, Amagasaki-sh, Hyogo 92, 6600892, JP)