Preliminary preparations for coring:

1. Hardness of the rock layer and degree of weathering of the bedrock inspection;

2. The stratum inspection of low conventional drilling efficiency or impossible to drill;

3. Check the integrity height of the bedrock, and undeveloped fracture or less developed. 

In this condition, to ensure the continuous drilling and the drilling effect, a barrel coring drill bit could be prepared.

Barrel coring drill bit

The drill rod is attached with a lock head, which locks each section of the drill rod through a mechanical locking point, and transmits the pressure to the drill tool. The pressure load could reach 95% or above, generating a large shear force between the drill tool and the rock mass, which is suitable for hard rock formations.

The drilling speed should be fast

Drill the coring drill bit and cut out the ring groove, and then grind the core off and take it out as a whole. Change the line contact of the drill teeth to a rotary ring contact, to reduce the contact area of the drill bit works on the rock layer, so as to reduce the running resistance of the drill bit when rotating, and to reduce the work required for comprehensive grinding and crushing of the rock layer. Under normal circumstances, there is no need to replace the drill bit to realize rapid drilling. 25M-40M can be drilled every day according to  the strength of the rock layer.