Fundamental Study On The Hybrid-driven Programmable Mechanical Press

The main feature of hybrid-driven linkage is to combine the motion of a large constant velocity motor with a small servomotor via a two degree of freedom mechanism. The former provides the main power and motion required, while the latter acts as a motion modulation device. Therefore, the hybrid-driven linkage can provide for programmable motion output.Firstly, the typical kinetic rules and driven scheme of the mechanical presses are reviewed. The scheme of hybrid-driven mechanical presses is put forward. Then the feature of hybrid-driven mechanical press is analyzed and the feasibility of hybrid-driven mechanical presses is discussed. The mechanism type of the hybrid-driven mechanical press suitable for deep drawing is selected. To begin with the analysis of the link length for a planner five-bar, the type of the planner five-bar linkage is analyzed. Then the forward and inverse kinematics of the hybrid-driven press is analyzed by using loop vector method. On the basis of the kinematical analysis, the equations of two crank's balance moment are studied considering the inertia of links.Secondly, in order to realize the flexible output of the slider, the optimum design of the hybrid-driven is carried out through two major processes. The first process is to optimize the geometric parameters of the press, on the assumption that the servomotor rotates at a constant angular velocity equal to that of the constant velocity motor. The second process is to optimize the displacement trajectory of the servomotor based on the results of the first process while keeping the geometric parameter unchangeable. The input displacement of the servomotor is separately optimized using polynomial curve and Bezier curve. Thirdly, according to the equivalent circuit of the dc motor, the dynamical model is set up. Then, the dynamical model for the hybrid-driven press is developed using Lagrange's formulation. The system's equation is derived using expressions for the system energy function, its partial and time derivatives with respect to the defined generalized coordinates. The dynamical equation is then transformed into a system of first order equations. Fourthly, based on the control theory, the PID control model of the hybrid-driven press is set up. Then the proportional gain, differential gain and integral gain are optimized. The forth order Runge-Kutta method is chosen as the integration technique of computer simulation.