Real-time estimation of ball-screw thermal elongation based upon temperature distribution of ball-screw

The optical telemeter system has been developed, which converts the temperature of rotating spindle to the digital data and carries the digital data from LED on the rotating side toward PD on the stationary side by the optical data transmission. Based upon the temperature distribution of hollow ball-screw obtained by the telemeter system, the thermal elongation of the ball-screw is estimated as the one-dimensional thermal elongation. Estimation accuracy, which is the difference between the estimated thermal elongation and the measured thermal elongation, is -3.1similar to+3.2 mum for the thermal elongation of 50-60 mum over the length of 935.5 mm of the ball-screw.