Minimizing energy consumption for starting and stopping the planetary drive of crank presses by optimizing its parameters

Crank presses operate under severe dynamic conditions, where a significant portion of total energy consumption is associated with acceleration and deceleration of rotating masses during starting and braking rather than with the forming process itself. This study proposes an energy-based methodology for optimizing the parameters of a planetary drive in order to minimize starting work. A reduced dynamic model with concentrated inertial elements is developed to represent the motor, belt transmission, flywheel, planetary gearbox, intermediate gear train, and crank-slider mechanism. Analytical expressions for equivalent moments of inertia and starting work are derived, enabling the formulation of a dimensionless optimality criterion proportional to the starting energy. The optimization problem is defined with respect to the planetary gear ratio, intermediate gear ratio, and geometric inertia coefficients under practical design constraints. It is seen that for each overall transmission ratio a unique combination of stage parameters that ensures minimum energy consumption exists. Planetary configurations significantly reduce starting work compared to the conventional single-stage gear drives due to the favorable inertia redistribution. The obtained analytical correlations define rational parameter ranges and quantify excess energy consumption for non-optimal designs. The proposed approach provides a generalized framework for energy-efficient design and modernization of crank press drive systems.