PERCUSSION ASSISTED ROTARY EARTH BIT AND METHOD OF OPERATING THE SAME

摘要

A method of boring through a formation includes providing a drilling machine and drill string and operatively coupling an earth bit to the drilling machine through the drill string. An air flow is provided through the drill string at an air pressure less than about 0.7 Mpa (100 psi) and an overstrike force is applied to the earth bit, wherein the overstrike force is less than about 1 j/cm(5 ft-lb/in).