Numerical Analysis on Influence of Punch Speed on Fluid Pressure in Hydro Forming Process

Abstract

The hydroforming deep drawing process is one of the sheet metal forming process. The pressurized fluid is used as a medium in this process. Hydro forming technology provides an attractive alternative to conventional matched die forming, especially for cost - sensitive, lower volume production and for parts with irregular contours. The performance of deep drawing process can be enhanced by using the liquids. The process performance can be improved through improvement of parameters like draw ratio, thickness ratio, ratio of volume to surface area of product, no scratches developed on outer side of cup and formability index. In this process, the pressurized liquid is utilized for many purposes as the sheet metal blank is supported in entire forming process, elimination of fracture in deformation of cup and formation of wrinkles on the wall and edges of the cup are minimized. The liquid pressure effects on radial, hoop and drawing stresses of blanks in during the process. The liquid pressure is obtained from ANSYS Flotran CFD analysis software for using three oils such as castor oils, olive oil and heavy machine oil. The evaluation of oil pressures through change in the punch speed at constant punch radius. The pressure of oil is acting radially on surface of blank during the process. The radial pressure of oil is controlled by the blank holder pressure. As these two pressures are equal, the deformation of blank is uniform to get a required shape and also it prevents the blank failure during deformation. The pressure of oil depends on punch speed. The oil pressure increases with increase in the punch speed. The oil pressure is the dominant parameter for failure and success of forming of cups from the cylindrical blanks. This pressure of oil is used to evaluate the blank holding pressure. In this paper the numerical studies are carried on the effect of punch speed on oil pressure in hydroforming deep drawing process.