Vibrating boring tool for hard ground layers has an additional axial vibrator in the driving tip

摘要

A vibrating boring tool has a shaped bit with a radial vibrator comprising a rotating mass (4) to drive the shaped bit into the ground. An additional vibrator (6) in the head of the boring bit generates axial vibrations for faster penetration of hard ground layers. A vibration damping insert (5) is positioned between the vibrators while a conventional damping insert (10) is positioned between the boring bit and the support (9). The axial vibrator operates as a hydraulic/pneumatic hammer. The vibrators are powered by electric, hydraulic or pneumatic motors. The boring bit has an integral feed for ballast material to backfill the hole when the bit is withdrawn.