| 摘要 |
PURPOSE:To prevent a drill bit from buckling or breaking by utilizing a D.C. servomotor for a cutting feed of a boring machine and controlling the speed of the feeding. CONSTITUTION:A deep hole boring is effected by repeating steps of quick feedings, cutting feeds and quick returning motions of a spindle 5 by utilizing a D.C. servomotor 13 capable of controlling feeding speed of the spindle. Thrust load for cutting is detected as the armature current of the D.C. servomotor, and when the thrust is increased due to wear of a drill bit, the speed of the feeding is decreased in accordance therewith, and further, when the wear of the drill bit is more increased, an instruction to exchange the frill bit is indicated. The current of said motor is transduced into voltage by an I/V transducer and the voltage is compared with a preset value against the thrust, and thereby, the feeding speed of the motor 13 is controlled. |
