A method of pre-tightening force control for the mini-bolt joint precision assembly

摘要

An improved torque control method-torque/time control method is proposed. The correlation between torque and Pre-tightening force is theoretically analyzed in the bolt joint assembly procedure, from which the equation of the torque and pre-tightening force is acquired in a system of stiffness invariable. When take the slope of torque-time changing and system stiffness of joint parts into consideration, the equation can be used to calculate the controlling torque in accordance with pre-tightening force and finally achieve the accurate control of pre-tightening force. According to the principle above, a mini-bolt joint assembly device and pre-tightening force measurement device was developed. The primary experiment results shows that accurate control of pre-tightening force can be achieved, while the dispersion of the controlling torque is high to some extent, the dispersion of the Pre-tightening force can still be acquired much low.