A Real-Time Measuring Method of Spindle Center Transition for NC Lathe
Hiroshi Mizuguchi*, Mikio Iwakiri*, Yutaka Ido*, and Hidenori Shinno**
*Development & Manufacturing HQ, MORI SEIKI CO., LTD.
201 Midai, Iga, Mie 519-1414, Japan
**Precision and Intelligence Laboratory, Tokyo Institute of Technology
4259-G2-19 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
Thermal displacement in the spindle system has great influence on the machining accuracy. Therefore it is very important to evaluate the thermal displacement of the spindle precisely. In the conventional measurement method for thermal displacement of the spindle, the measurements were taken during no-load running with non-contact sensors put close to the outside of a workpiece. However, in fact, it is essential to evaluate thermal displacement of the spindle while a machine tool is machining a workpiece actually. The measurement of the thermal displacement of the spindle during actual machining is generally difficult. In this paper, we propose a new method by which we measure thermal displacement of the spindle while we are actually machining a workpiece with an NC lathe. The experiment was performed with various cutting conditions and the result of the thermal displacement of the spindle corresponding to each condition was observed. Then, by analyzing the experimental result, we obtained mathematical models that show the relation between thermal displacement and spindle motor output.
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