The Dynamic Performance Analysis And Optimization Design Of High Spot Closed Gripper Mechanism Of Offset Press

The high spot closed gripper mechanism is one of the key mechanism in the offset press, the performance of the mechanism will directly affect printing speed and printing quality of the offset press. When the mechanism’s speed increases, the printing quality reduces and the noise and shock increase rapidly. Then the kinematics and dynamics analysis on the mechanism, revealing the reasons of impact and noise of the mechanism in the movement process. Then the cam of the mechanism is optimized, and the expected effect is obtained.The main contents and innovations of this paper are as follow:(1) According to the particularity of the movement of the mechanism, the kinematics law of the institution is derived deeply by comprehensive knowledge of kinematics. Combined with the actual parameters, the law of motion of mechanism’s pendulum follower and dental films vertex are obtained.(2) A three-dimensional solid model of the mechanism is established in SolidWorks, the model is imported into the MSC/ADAMS software. The rigid body dynamics simulation is done in the MSC/ADAMS software. The contact force curves between the cam and the roller and the hinged force curves of pendulum and tooth shaft junction are obtained under different conditions.(3) Combined with the movement characteristics of the mechanism, the cam curve of five polynomials and modified trapezoidal acceleration are selectted. Then combined with motion curve of the mechanism follower, the cam curve of modified trapezoidal acceleration is chosen as the movement of mechanism follower at last. Then the contour line of the cam is obtained by using the trajectory tracking method in the COSMOS/Motion software.(4) The cam optimized is brought into the original model, and the motion law and force curve of the follower is obtained. By comparison with the curves before optimization, we can find that the motion curve becomes smooth, the amplitude of speed and acceleration decrease, the magnitude of the force curve decrease when the cam contours is optimized.(5) According to the feature of the elastic deformation of components when the mechanism is under high rotation speed characteristics, a lumped mass model of the mechanism is established. According to the principle of simplified dynamic model, the mechanism model is simplified into a single degree of freedom model. The motion response curve in the actual state of motion is sloved by the numerical method.