ボールねじ熱膨張のリアルタイム補正による位置決め精度の向上（第1報）: 補正の原理と運転条件の影響

摘要

This paper deals with the improvement of positioning accuracy of machine table by real-time compensation of thermal elongation of ball-screw. During operation the temperature distribution at fifteen positions of the hollow ball-screw is measured and input into the personal computer by the optical telemeter system developed. Based upon the increase of the temperature distribution and the present position of machine table obtained from CNC controller, the thermal elongation of the ball-screw between the thrust support bearing and the ball-screw nut of machine table is estimated by the PC. The estimated value is fed from the PC to CNC controller as the compensation value, and the origin shift of the machine coordinate is immediately executed. These measurement and control are repeatedly executed during operation, and the real-time compensation is realized. Machine table position is measured by a laser displacement measure ment system. It is clarified that the positioning accuracy of ·7.1～+0.3μm is realized over 555mm length under the table speed not greater than 18m/min.%最近，ボールねじ駆動のNC工作機械でも　90～100m/minrnの最高送り速度が達成されている．これに伴う支持軸受部発rn熱量の増大およびボールねじ·ナット開発熱量の増大により，rnボールねじ熱膨張量が増大するので，位置決め精度が低下すrnる．