| 摘要 |
<p>This vertical hole-boring machine bores a vertical hole by applying rotary boring force and thrust to at least a bit of a drill string to a predetermined depth, whereupon another component of the drill string is added, and the boring is continued. This invention is designed to solve the problem of connecting new components to the drill string safely and within a short period of time. In order to solve this problem, this invention comprises bearing means for bearing at least the lower end of the component of the drill string which is to be connected, support means for stably and movably supporting the bearing means at the connection position and a standby position, and holding means for holding the drill string as it is being connected. </p> |
