发明名称 |
Reverse circulation down-the-hole hammer drill and bit therefor |
摘要 |
A reverse circulation down-the-hole hammer drill apparatus for drilling rock and overburden comprises a fluid-driven piston which reciprocates in an annular chamber to repeatedly strike a bit suspended at one end of the chamber, for example in a splined mounting. Fluid is exhausted through the bit directly to the face of the bit and cuttings and debris are returned via a central throughbore in the bit and in the drill apparatus to the surface. The bit drops forward on encountering a void during drilling operations to open by-pass passages which exhaust fluid directly into the throughbore temporarily so as to prevent any loss of return of sample to the surface.
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申请公布号 |
US4819746(A) |
申请公布日期 |
1989.04.11 |
申请号 |
US19870134833 |
申请日期 |
1987.12.18 |
申请人 |
MINROC TECHNICAL PROMOTIONS LTD. |
发明人 |
BROWN, JOHN C. A. T.;PURCELL, PATRICK;SWEENY, PETER J. |
分类号 |
E21B4/14;E21B10/38;E21B21/10;E21B21/12;E21B44/00;(IPC1-7):E21B4/14;E21B10/60 |
主分类号 |
E21B4/14 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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