Title:
【発明の名称】リングビットを用いた掘削方向修正容易な掘削方法及びリングビット
Document Type and Number:
Japanese Patent JP2694297
Kind Code:
B2
Inventors:
Takayuki Abiru
Kurosawa Masami
Kurosawa Masami
Application Number:
JP19603489A
Publication Date:
December 24, 1997
Filing Date:
July 27, 1989
Export Citation:
Assignee:
New Technology Koei Co., Ltd.
International Classes:
E21B7/04; E21D9/06; E21D9/08; (IPC1-7): E21D9/08; E21B7/04; E21D9/06
Domestic Patent References:
| JP57143095A | ||||
| JP5087722U | ||||
| JP534604U | ||||
| JP425789B1 |
Attorney, Agent or Firm:
Shoshiro Tojima