Research On Technique Of Improving Dynamic Performance Of Die-Cutting Machine

Automatic die-cutting machine is one of the most important equipments in printing industry, high speed, high precision and high efficiency have become the important trend of it. In this paper, kinematics and dynamics of cam mechanism and die-cutting mechanism in die-cutting machine are studied and some measures are carried out in order to improve it's performance.First, dual-elbow-bar mechanism is the core component as the die-cutting mechanism. It's mechanical function will directly affect the working ability. This paper introduces a method of it's kinematic analysis based on Product of Exponentials Formula. By using this method, kinematic analysis of dual-elbow-bar mechanism in die-cutting machine is carried out and kinematic equations are built. The Virtual Prototyping model of dual-elbow-bar mechanism is also built with ADAMS, kinematic and dynamic simulation are also given. The angular displacement, angular velocity, angular acceleration and the corresponding curves of each component in a motion period are obtained. The results agree with the analysis based on Product of Exponentials Formula. The optimum design with three variables is carried out, it can be seen that the kinematics performance of it is improved clearly. An innovative die-cutting mechanism drived by dual-cam mechanism is designed. And then taking into account the clearance between the linkage and crank, the analysis of kinematic and dynamic is given.On the basis of kinematic analyzing, virtual prototyping model of cam mechanism is built with ADAMS. Motion characteristic of cam is carried out, after the motion rule is analyzed, MS motion rule is chosen, and according to it better cam profile is designed. The dynamic performance of cam mechanism is improved. Meanwhile, the C program which is used to improve the motion characteristic of cam is developed. Two method are carried out to decide motion rule if Parallel Indexing Cam profile is known, an example is given. The follower seperation is a major impediment to the increase of operating speed of force-closed cam mechanisms. A mathematical model is developed for analyzing the critical time of follower seperation. The proper preload and stiffness of spring is obtained. The oil film between the camshaft and follower surfaces can be regarded as a system with mass, spring and damping. The film thickness, the equivalent stiffness of the film and the dynamic model of cam mechanisms are considered.