Energy optimization of main hydraulic system in a forging press by simulation and experimental methods

The primary cause of the low energy efficiency of hydraulic presses (HPs) is the mismatch between installed power and demanded power. This study adopts the concept of a high-pressure waterjet cutting system and presents an energy-saving method to reduce the energy dissipation of HPs, where a single drive system composed of multi motor-pumps and superchargers-accumulators, is integrated into an HP and partitioned into several drive zones corresponding to load profiles. Meanwhile, a method for scheduling the above system is presented to realize an orderly energy supply with no conflict and shorten the idle time. Pump units, accumulators, and superchargers were selected according to the different load profiles to energize the actuators in various operation stages. Since the kinetic power of the hydraulic oil output from superchargers are significantly higher than those of a conventional power unit, a press with low installed power could achieve high power load operations. Finally, the proposed system was applied to a 31.5 MN forging HP as a case study. Results showed that the installed power and the energy dissipation were reduced by 56% and 52% in one working cycle, respectively. Moreover, the novel HP displayed a processing performance equivalent to that of the conventional setup.