Kinematic optimization of mechanical presses by optimal synthesis of cam-integrated linkages

The paper proposes a method for the synthesis of planar mechanisms, where a combination of cams and linkages is used in order to improve the kinematic behaviour of mechanical presses. The purpose is to synthesize a function generating mechanism, with a constant input-velocity, able to move the press ram according to an optimal law of motion. The proposed synthesis methodology consists of two phases. As a first step, a linkage type-synthesis is performed, based on the mobility the generation task requires. An initial multi degree-of-freedom (d.o.f.) mechanism is thus selected. One or more disc cams are then synthesized in order to reduce the system's mobility and to obtain a single-input combined mechanism. The final system is able to generate a specific input/output relationship, as defined by any number of precision configurations. In order to optimize the synthesis process, according to dimensional and kinematical criteria, a genetic algorithm is employed. A goal function is defined on the basis of both performance criteria and design rules, and minimized by means of evolutionary theory. The proposed methodology is applied to the kinematic optimization of mechanical presses for deep drawing and precision cutting processes.