Pressure control of a drilling apparatus
US6293359A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 5, 2000 |
| Grant date | Sep 25, 2001 |
| Priority date | — |
| Expiry date | Jun 5, 2020 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B19/086
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Apparatus for blast hole drilling includes a hammer and drill bit driven by a hydraulic drive motor outside the hole through a drill string extending along the drilled hole to the drill bit. The drive motor is carried on a mast with a telescopic hydraulic cylinder driving the motor along the mast in a forward direction for forwarding the drill bit along the hole to the rock face and for applying a feed force on the drill bit at the rock face and in a rearward direction for reducing the feed force and for withdrawing the drill bit from the hole. The cylinder assembly has a pulldown pressure side fed at a constant supply rate and a holdback pressure side controlled to discharge the fluid when moving downwards and to supply the fluid at a constant rate when pulling up. The control system includes a first valve for controlling a rate of supply of fluid to the motor for controlling the rate of rotation of the drill bit, a drilling valve operable to supply fluid to the pulldown side or to the holdback side, a second valve for controlling the rate of supply of fluid to the pulldown side, a third valve for controlling the rate of discharge of fluid from the holdback side, a hydraulic feedb…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.