The diamond bit generates a lot of heat and cuttings when drilling at high speed. In order to ensure the proper circulation of the wash/slurry, water outlets and internal and external flume must be designed in the end part of the drill body.
The shape and number of water orifice have a certain influence on the drill footage efficiency. At present, there are four kinds of water orifice shapes commonly used in geological coring bit, namely, straight water orifice, positive spiral water orifice, reverse spiral water orifice and bottom water orifice.
The spiral nozzle is designed to solve the problem of poor circulation in the case of high concentration of washing liquid or mud slurry. Positive and reverse circulation nozzle respectively correspond to the drilling of positive and reverse circulation drilling tool. The huge whirlpool generated during high-speed rotation can speed up the flow rate of liquid and achieve the purpose of efficient penetration. The bottom jet nozzle is commonly used in the coring bit with rope, in order to prevent the plug of the nozzle from burning the drill.
However, the actual effect is not very obvious, and it has a negative effect on the footage efficiency of the bit, so it is not widely used. The most used is the straight water nozzle, not only this design helps the processing of the bit, in the actual drilling process is easier to make debris discharge, speed up the liquid circulation, protect the head of the drill body at the same time speed up the footage efficiency, the drill is using this water nozzle design.
