Title:
BILLET DRILLING METHOD
Document Type and Number:
Japanese Patent JP2000190006
Kind Code:
A
Abstract:
To obtain a seamless steel pipe without inner surface defect by using a continuously cast billet.
This invention relates to a method to drill continuously-cast billet of a seamless steel pipe material with a drilling roll having barrel type body. In this case, a concave portion 2 whose diameter is 0.1-0.3 times the outside diameter of the billet 1 and whose depth is 1-3 times the outside diameter of the billet 1 at the center of the bite side edge of the billet 1, is formed before drilling.
Inventors:
YASUNAGA KATSUSHI
YAMAZAKI MOTOHARU
TAKAOKA TATSUO
IKUI KENJI
YAMAZAKI MOTOHARU
TAKAOKA TATSUO
IKUI KENJI
Application Number:
JP36581798A
Publication Date:
July 11, 2000
Filing Date:
December 24, 1998
Export Citation:
Assignee:
NIPPON KOKAN KK
International Classes:
B21B19/04; (IPC1-7): B21B19/04
Attorney, Agent or Firm:
Shigeru Takano