Machining, Measurement, and Control Laboratory

High Speed and High Productive Tapping by Intelligent Machine Tools (3rd Report)
- Prevention of Tap Tool Breakage and Monitoring of Tool Failure for Difficult-to-machine Materials -
Yoshinori Yamaoka (Yamazaki Mazak Corp.)
Yoshiaki Kakino (Kyoto University)
Makoto Fujishima (Mori Seiki Co., Ltd.)

This paper presents a method of real-time adaptive control of tapping for the difficult-to-cut material such as superheat resistant alloy (Inconel 718), titanium alloy (Ti-6Al-4V), and stainless steel (SUS 304). Normally adaptive control has disadvantage to be applied in tapping process because C-axis requires high acceleration in the process. In general, conservative cutting speed is applied to such difficult-to-cut materials, since high cutting speed intensify tool wear. Moreover, only in the case with low cutting speed, C-axis is able to be operated with high acceleration to stop its rotation. Therefore, real-time adaptive control such as adaptive pecking is effective for these materials. By introducing adaptive control, chip jamming is avoided during tapping processes. In addition, it is possible to predict the tool life by counting the number of pecking in successive tapping process.

Key words: Intelligent machine tools, tapping, adaptive control, difficult-to-cut material.