Title:
ROCK DRILL
Document Type and Number:
Japanese Patent JP2613538
Kind Code:
B2
Abstract:
PURPOSE: To draw out a bit easily by changing over a valve when the bit can not be dravm off after the boring work, supplying oil pressure to a reverse cylinder, and giving a backward striking force to a shank rod.
CONSTITUTION: Oil pressure is supplied to a cylinder 11a of a positive striking device 10, and a positive striking piston 15 is advanced to strike the tail of a shank rod 32 in the forward direction, and boring takes place with this striking force. In case the bit is not able to be drawn off after the boring, a changeover valve is switched so that the oil pressure is supplied to a reverse cylinder 61 of a counter-directed striking device 60. This causes an advance of a counter- directed striking piston 65 provided inside of the reverse cylinder 61, and the collar front face of the shank rod 32 is struck backward which enables drawing- off of the bit.
Inventors:
Tsuneo Iwasaki
Kazuo Haga
Kazuo Haga
Application Number:
JP13277193A
Publication Date:
May 28, 1997
Filing Date:
May 10, 1993
Export Citation:
Assignee:
Yamamoto Rock Machine Co., Ltd.
International Classes:
B25D9/12; E21B1/00; E21B1/26; E21B7/00; (IPC1-7): E21C3/20
Domestic Patent References:
| JP5854197A | ||||
| JP526277U |
Attorney, Agent or Firm:
Hiroshi Sugawara