Operation scheduling of multi-hydraulic press system for energy consumption reduction

Abstract

Reducing energy consumption is becoming a more and more essential consideration for low carbon manufacturing. In this paper, an operation scheduling approach is proposed for a multi-hydraulic press system to explore the potential on energy saving at system level. In the multi-hydraulic press system, a drive is composed of several motor-pumps and supplies energy to each press according to a given schedule. The scheduling formulation is developed based on power models of the forming process on an individual press. At single press level, models of energy conversion units, including asynchronous motors, piston pumps, hydraulic cylinders, valves and pipes are built by identifying their energy dissipation characteristics. Based on the established model of a single press and scheduling formulation, the energy consumption model and makespan at multi-press level are obtained. In order to balance makespan and energy consumption, the duration of each operation is adjusted by optimizing the configuration of the drive and the schedule of operations. To demonstrate the applicability of the proposed approach, a case study on a four presses system is presented. The results show that this approach is effective in identifying schedules to reduce makespan and total energy consumption during forming processes.