Drilling tool comprises fixed cutting edges mounted on body containing reservoir and calibrated circuit which sends drilling fluid to cutting elements at controlled rate

摘要

A drilling fluid circuit has a reservoir inside the tool body which is connected upstream to a calibrated nozzle and downstream to at least one opening near the cutting elements. The nozzle has several calibrated orifices. The chamber is a revolution around the axis of the body and the calibrated orifices are placed symmetrically around the axis of the body. The calibrated orifices have controllable section, obtained by superimposing two plates pierced with holes, which overlap and can be displaced relative to each other. The reservoir has a larger cross section at its downstream end. The downstream opening contains nozzles which pass through the wall of the reservoir. The cutting elements are fixed to metal arms fixed to the body of the tool and the opening forms cut-outs between the arms. Alternatively, the opening is a circular or polygonal hole formed axially in the body of the tool and the cutting elements are fixed to the metal arms fixed to the body of the tool to overhang in front of the hole.