Abstract

The invention relates to a down-the-hole drilling device (1) for drilling to be performed with a casing pipe, wherein the drilling device comprises in its drilling head: a drilling arrangement having first drilling means for drilling a center hole and second drilling means for reaming the center hole for the casing pipe; and a flushing flow arrangement for feeding of a pressurized flushing medium onto a drilling surface of the drilling arrangement by a feed flow arrangement that is arranged to lead the flushing medium for drilling onto the drilling surface (P1) of the first drilling means at a flushing channel assembly (6a1) therein in essentially radial direction. The drilling surfaces of the first and second drilling means are provided with cutting inserts (10a) submerged therein. The drilling surface (P1) of the first drilling means comprises a protrusion assembly (PT) in order to enhance drilling efficiency and to guide drilling waste at the flushing channel assembly (6a1).

IPC Classes  ?

• E21B 10/61 - Drill bits characterised by conduits or nozzles for drilling fluids characterised by nozzle structure
• E21B 7/20 - Driving or forcing casings or pipes into boreholes, e.g. sinkingSimultaneously drilling and casing boreholes
• E21B 10/60 - Drill bits characterised by conduits or nozzles for drilling fluids
• E21B 10/64 - Drill bits characterised by the whole or part thereof being insertable into or removable from the borehole without withdrawing the drilling pipe

Abstract

The invention relates to a method in down-the-hole drilling and a down-the-hole drilling device, being meant for drilling a hole with and a casing pipe (2). The drilling device comprises in its drilling head (I) : a drilling arrangement having first drilling means (4) for drilling a center hole and second drilling means (5) for reaming the center hole for the casing pipe (2); and a flushing flow arrangement (6) for feeding of a pressurized flushing medium onto a drilling surface (P) of the drilling arrangement by a feed flow arrangement (6a). In the method the flushing medium for drilling is being led by the feed flow arrangement (6a) onto the drilling surface (PI) of the first drilling means (4). The feed flow arrangement (6a) is prevented from getting clogged with soil substance, due to releasing the pressure of the flushing medium, by one or more feed channels (6a') of the feed flow arrangement (6a), having a cross section that expands toward the drilling surface (PI) of the first drilling means (4).

IPC Classes  ?

• E21B 10/61 - Drill bits characterised by conduits or nozzles for drilling fluids characterised by nozzle structure
• E21B 10/60 - Drill bits characterised by conduits or nozzles for drilling fluids
• E21B 7/20 - Driving or forcing casings or pipes into boreholes, e.g. sinkingSimultaneously drilling and casing boreholes
• E21B 10/18 - Roller bits characterised by conduits or nozzles for drilling fluids
• E21B 10/26 - Drill bits with leading portion, i.e. drill bits with a pilot cutterDrill bits for enlarging the borehole, e.g. reamers
• E21B 10/38 - Percussion drill bits characterised by conduits or nozzles for drilling fluids
• E21B 10/62 - Drill bits characterised by parts, e.g. cutting elements, which are detachable or adjustable
• E21B 10/64 - Drill bits characterised by the whole or part thereof being insertable into or removable from the borehole without withdrawing the drilling pipe