| 摘要 |
PROBLEM TO BE SOLVED: To precisely detect the expansion magnitude only with the measurement of a shifting quantity by estimating the expansion magnitude from the measured value of the shifting quantity of an actuator and estimated values of friction force, coefficient of viscous friction and mass of the driving part driven with the actuator. SOLUTION: The generating force of the actuator is gradually raised and this force is obtained as the friction force FD of the driving part at the time when the actuator is started to move, and the shifting speed dx/dt of the actuator (x is the shifting quantity of the actuator and t is time) is obtained for the time until an electrode tip part reaches a member to be welded by increasing the generating force F to a prescribed level. From this shifting speed, the speed when the shifting speed becomes constant is obtained, and from this speed the estimated value Da of the coefficient of viscous friction in the driving part is calculated by the equation I, and the estimated value Ma of the mass in the driving part is calculated by the equation II (t1 is the time till reaching the dx/dt (max) while using the estimated value Da) and the expansion magnitude Xn is estimated by the equation III (k is spring coefficient of a welding gun arm).
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