Pressure Modeling and Analysis of a Synchronized Hydraulic Press Brake With Variable-Speed Pump Available to Purchase

This paper presents a theoretical–experimental pressure analysis of a hydraulic press brake with synchronized cylinders. In this machine, the motion of each cylinder is controlled by independent variable-speed electrical motors. This design has many benefits over traditional solutions using hydraulic proportional valves, such as higher energetic efficiency, nonrequirement of a heat exchanger, lower oil-cleanliness requirement, and reduced audible noise. However, a critical characteristic of the press brake is the use of double acting cylinders with large rods controlled by a pump in a closed circuit. In the studied system a cap end area roughly eleven times greater than the rod end area is used. Furthermore, the synchronized hydraulic press brake operates in six stages with particular characteristics implying in different flow rate demands and pressure behaviors. Based on experimental results, the pressures in specific parts of the circuit are analyzed and critical operational conditions are identified. A simulation model using Hopsan is validated and used to propose a hydraulic circuit modification. The proposed solution eliminates the tendency for pump cavitation and pressure surges that occur during the press break operational cycle.