HELICAL DRILLING APPARATUS, SYSTEMS, AND METHODS

摘要

A down-the-hole assembly includes
a housing having a central axis and a mechanical
gear box positioned within the housing. The mechanical
gear box is coupled to the housing such
that rotation of the housing at a first rotational rate
provides a rotary input to the mechanical gear box.
A rotary cutting bit is coupled to the mechanical
gear box. The mechanical gear box is configured to
rotate said rotary cutting bit at a second rotational
rate in response to that rotary input from the housing.
The second rotational rate is greater than the
first rotational rate. The mechanical gear box is also
further configured to cause the rotary cutting bit to
orbit about the central axis of the housing.