Machining, Measurement, and Control Laboratory

2 0 0 1    J o u r n a l    P a p e r

High Speed, High Productive Tapping by Intelligent Machine Tools (2nd Report)
-- Prevention of tap tool breakage and improvement of productivity by adaptive control --
Yoshinori Yamaoka (Yamazaki Mazak Corp.)
Yoshiaki Kakino (Kyoto University)
Tomonori Sato (Mitsubishi Electric Corp.)
Yasuhiko Suzuki (Yamazaki Mazak Corp.)

This paper presents a method of adaptive control of tapping in order to perform high speed, high productivity tippling by using newly developed intelligent machine tools experimentally. Generally the adaptive control is changing of cutting condition like feed rate and cutting speed. For tapping, it is not enough to avoid troubles that control cutting condition as compared with other machining modes like drilling and milling. Because feed rate is fixed for pitch of tap, and to control cutting speed is not so effective. This method means changing acceleration speed of tapping by means of the value of cutting torque by monitoring cutting force with internal sensor. To use this method, the cutting force increase is not so sharp at the hole bottom vicinities because of prevention of chip jamming. In order to inspect the productivity and safety of tapping, a new NC system produced. As a result, productivity improved 34% experimentally as compared with conventional system. So it is able to have high-efficiency machining without tool breakage in tapping.

Key words: intelligent machine tool, tapping, adaptive control

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