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

Abstract

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.

Analyzing an error in the synchronization of hydraulic motor speed under transient operating conditions

“…Transient operating conditions of hydraulic motor operation were mentioned only in [8,15,[20][21][22] but detailed analysis of such operating conditions was not made.…”

“…For example, results of simulation of pressure in cavities of synchronized hydraulic cylinders of a brake fed from a pump with controlled flow rate were presented in [20].…”

Optimization of Hydraulic Drives for Synchronizing Working Movements of Automated Brick Production Installation

“…The obtained results improve stability and speed of the lifting process. In work (Teixeira et al, 2015) theoretical and experimental analysis of operation of a hydraulic brake press with synchronized cylinders, where movement of each of them is controlled by an independent variablespeed electric motor is represented. Such design has a number of advantages but it is important for the system to use double-acting cylinders with defined parameters.…”

Design and Optimization of a Fast Switching Hydraulic Step-Down Converter for Position and Speed Control

“…One approach is either the velocity and position control using variable displacements pumps and motors [3] or fixed and variable pumps driven by variable speed electrical motors [4] [5]. Moreover, another technology in development is the digital hydraulics [2] [6] [7] [8].…”