CB is a special drilling tool. By cutting an annular groove, the core can be broken by hammer or screw bit.
Because of different welding cutting rings, barrel drills are divided into four types: CB-I, CB-II, CB-III and CB-IV.
It is difficult to drill directly with spiral drill or rotary drill for hard base rock stratum, large cricstone layer and hard permafrost soil layer, so cylinder type ring bit is needed to drill with spiral bit and sand drill. It is divided into a coring circular cylinder bit and a non coring ring drill bit. According to the different drilling strata, it is divided into a cutting ring drill which can be used for the drilling of the weathered base rock and permafrost soil layer, and the annular cylinder type bit for drilling hard bedrock. The structure features and principles of the coring circular cylinder bit are: two layers of bucket body inner pipe and outer tube, the main cutting teeth on the outer tube, the auxiliary cutting teeth on the inner tube, and the hinge plate with the core core on the lower end of the inner tube.
When drilling, the core opens the hinge into the pipe, and when lifting, the hinge plugs the core into the pipe by the weight of itself, and brings the core out of the hole. The structure characteristics and working principle of the non coring circular cylinder bit: the cutting teeth are directly welded in the lower part of the drill barrel, and the barrel type bit is first drilled into a cylindrical shape when drilling, and then the circular core is broken into pieces by the spiral bit, and then the pieces are removed.
Operation precautions: the drill can be lifted when the drill is full, and it must be slow when the drill is drilled. Because the drill has the inside out edge, the core bit can be taken out of the core or the big boulder, if it can not be taken out of the normal, because it is mainly to form all the free surface, so that the sand bucket or the spiral drill head can be drilled.
