Development of Secondary Controlled Hydraulic Pressure Forming of Sheet Metal for Energy Saving and Re-Utilization:

Abstract

This paper presents the development of secondary controlled hydraulic pressure forming of sheet metal for both potential energy saving and electric motor power consumption reduction. Most of the reported existing pressure forming processes have limited pressure application and are mostly used for batch production. Above all, none of the existing processes use hydraulic accumulator and hydraulic transformer to save and reuse the energy or convert the system pressure and flow to the predetermined load requirement which could prevent wrinkling and fracture effect caused by low and unduly high pressure. Instead, most of the processes throttle excess fluid that is not required back to the reservoir thereby wasting excess motor energy as well as generating heat to the system. The resultant effect been the use of much energy during metal forming operation that leads to enormous financial lost to companies. It was as a result of these problems that the research was carried out. This development uses two secondary units (the hydraulic transformer) to transform a low pressure/high fluid flow into a high-pressure/low fluid flow. The use of variable speed drive (VSD) unit prevents pressure surges and ensures smooth starting and stopping of the machine. The hydraulic punch unit coupled to the hydraulic cylinder (ram) on a single action stroke performs the forming operation when the cylinder rams strikes. During ram retraction, the system saves and recycles both the hydraulic energy and generated heat back into the accumulator. The highly pressurized fluid generates a force of about (1500kN) which is used to power the punch piston for steel forming of thickness between 1.00mm-2.5mm. This operation leads to mass production of high strength, quality surface textured metallic parts within a second. The system simulation is performed using SIMULINK. The experimental results does not only agree with theoretical analysis but also appears to prove that the system is very efficient in energy saving and recuperation.