| 摘要 |
A boring apparatus, such as a drilling apparatus for forming holes in pressurized pipes, comprises a cutting head (5) mounted to a distal end of a boring bar (2) which is itself connected to a feed screw (3) by a feed nut so that relative rotation between the boring bar (2) and the feed screw (3) cause the cutting head (5) and boring bar (2) to traverse axially along the feed screw (3) while the cutting head (5) is rotated for cutting. The apparatus has a main drive motor arranged to drive the cutting head (5), boring bar (2) and a main drive shaft (4). The main drive shaft (4) and the feed screw (3) are operably connected at the proximal end through a pair of adjacent coaxial planetary gear assemblie (6) whose planetary gear carriers are liked to rotate in unison about the axis. An independent, primary feed drive motor is geared to a planetary gear ring (20) and is operable to provide a difference in rotation velocities between the feed screw (3) and boring bar (2) whereby the movement of the cutting head (5) and boring bar (2) to and from along the axis may be controlled. |
