PURPOSE: To prevent large noises and increase drilling efficiency, by giving a torque and an oscillating force in the axial direction to the main shaft connected with a boring rod at the front end.
CONSTITUTION: A torque is given to a main shaft 21 connected to a boring rod 11 at the front end thereof by a rotary drive device 2 and in addition it, an oscillating force to the axial direction is acted on the rod by an oscillator 3. The main shaft 21 is transferred to the axial direction by a feeding device like a feed chain to feed it into the ground or pull it from the ground. Accordingly, the boring rod 11 vibrates in the axial direction while rotating to loosen the ground surrounding the front end and cause fluidizing phenomenon. Hence, it reduces the drilling resistance and it does not give large impulses to the boring rod 11.
YOSHIDA MITSUHIRO
YOSHIDA RIKIO
JPS60141987A | 1985-07-27 |