DEEP HOLE DRILLING APPARATUS

摘要

A deep hole drilling apparatus which prevents development of a tool mark. The deep hole drilling apparatus comprises a tool (12) for drilling a deep hole (Wa) in a work (W) by rotation drive, an accelerometer (19) for detecting the vibration of the tool (12) as acceleration during deep hole drilling, a monitoring unit (20) for analyzing the frequency of the detected acceleration and judging that a tool mark is produced in the deep hole (Wa) when the overall values of the whirling natural frequency and the bending natural frequency in the frequency range other than the frequency of the torsion natural frequency caused at all time during deep hole drilling exceed predetermined thresholds (E), and an NC machine (18) for controlling the rotational speed and the feed speed of the tool (12) according to the judgment made by the monitoring unit (20).