Integrated Cam Contour Optimization Method Considering Kinematic and Dynamic Characteristics: A Paradigm of Offset Press Open-Close Gripper Mechanism

To efficiently search out the optimal cam contour, a software integrated optimization method considering cam mechanism’s kinematic and dynamic characteristics was presented, and its effectiveness was demonstrated by a case study of the cam contour optimization for an offset press open-close gripper mechanism. The acceleration curve and the residual vibration model of the follower were separately studied. A symmetric harmonic trapezoidal curve was designed to control the follower’s acceleration, and single-DOF lumped parameter torsional vibration model was proposed to describe the follower’s residual vibration. Accordingly, corresponding motion curve design software and Simulink vibration model of the follower were developed respectively, and they were integrated into an automatic optimization platform with iSIGHT. The multi-objective optimization with objectives of minimizing both the acceleration and the residual vibration of the follower was completed within the platform by using NSGA-II algorithm. An appropriate point with lower acceleration and residual vibration was chosen from Pareto front as an optimal solution of the follower’s motion curve. Based on the follower’s new motion curve, the actual cam contour was generated by inverse kinematic simulation in COSMOSMotion. The offset press that installed our new designed cam exhibited a lower vibration than the previous machine, and the maximum measured acceleration of the offset press at a printing speed of 15 000 r/h is reduced by 7.7%.