Role of Viscosity in Hydro-forming Process

Hydro forming is new development in the manufacturing of various products in the field of engineering. In the manufacturing area one of the hydro forming process is Hydro forming deep drawing. Hydro forming deep drawing is one of sheet metal forming process to produce seamless shells, cups and boxes of various shapes. In this forming process, an additional element such as fluid pressure is to be contributes positively in several ways. In hydro forming deep drawing process, applying the hydraulic pressure on blank periphery in radial direction. It is obtained through the punch movement within the fluid chamber, which is provided in punch and die chambers. These two chambers are connected with the bypass path and it is provided in the die. During the process punch movement within the fluid chamber the pressure is generated in fluid and it is directed through the bypass path to blank periphery, the fluid film is created on the upper and lower surfaces of the blank and subsequently reduces frictional resistance and is to reduce tensile stresses acting on the wall of the semi drawn blank. The blank is taking at centre place in between blank holder and die surface with supporting of high pressurized viscous fluid. The radial stresses are produced in the blank in radial direction due to punch force applied on it. The shear stresses acted by viscous fluid on the both sides of blank, so apply viscosity phenomenon to this analysis. Due to the viscosity of fluid the shears stresses and shear forces acted on blank during drawing process. This viscosity used for determination of radial, hoop and drawing stresses in this process. The viscosity is maintained major role in hydro forming process. The blank holder pressure is controlled by the radial pressure of fluid and these are equal for uniform deformation of blank to obtained required shape and also elimination of failure of blank in deformation. Newton's law of viscosity is applied for this process for evaluation of stresses. The radial stresses are determined in terms of viscosity of castor oil, shear stresses, blank geometry and process parameters for magnesium alloy. The study on these stresses in castor oil medium with consideration of its viscosity.