| 摘要 |
PURPOSE:To high efficiently perform high load drilling by a drilling motor of small size, by driving a feed motor by AC half-wave power and then transferring the driving gradually to the AC full wave driving when an electric drilling machine, equipped with the feed control motor, is started. CONSTITUTION:An electric drilling machine 3 is mounted to a frame 1, and an electromagnetic base 2 to be fixed to a work is mounted to a bottom part of the frame 1. The electric drilling machine, immediately after it is started, drives a drill feed motor by half-wave power of an AC waveform feeding an electric drill in a slow speed. Under this condition, drilling is started, for instance, in a regular part. The feed motor is gradually switched from its driving by the half-wave power to that by the full-wave power in a stage where the drilling in the regular part is finished. Accordingly, the drilling can be performed in the maximum efficiency matching with drill performance.
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