Reverse circulation down-the-hole hammer drill and bit therefor
US4819746A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 18, 1987 |
| Grant date | Apr 11, 1989 |
| Priority date | — |
| Expiry date | Dec 18, 2007 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B44/005
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.