Theoretical and Numerical Analysis of Hot Deep Drawing of Hemispherical Thick Head

One of the common processes for the head production is welding which is done by joining preformed sheets. Manufactured product due to assembly error, metallurgical defects and weak mechanical strength of the joint, does not have adequate dimensional and mechanical quality. Therefore, the hot deep drawing is an alternative process in order to solve the aforementioned disadvantages due to the production of one-piece head. In the present paper, theoretical and numerical analysis of the manufacture of a hemispherical thick head made of HY-100 alloy steel with a sheet thickness of 63.5 mm using this process with a blank-holder is presented. In this study, the Johnson-Cook constitutive model is used to describe the flow behavior of the material and the Johnson-Cook damage model is used to predict the probability of failure. It is assumed that the process is carried out isothermal and the strain rate is constant. The results of theoretical analysis showed that the drawing force decreases with increasing temperature, decreasing friction, and increasing the radius of the die curvature. On the other hand, the results of the numerical analysis showed that the head was successfully formed. Also, no trace of wrinkling appeared in the flange and the greatest thickness reduction occured in areas near the top of hemisphere. On the other hand, the thickness of areas close to the flange, increases. The comparison between forces showed that drawing force values obtained from theoretical and numerical analysis under different temperatures and friction conditions differed by a maximum of 10%.