A slip-line method for calculating extrusion force of steel helmet with cold extrusion moulding

This paper presents the elastic and plastic deformation of the steel helmet with cold extrusion moulding. The plastic streamline of the plastic mould-making process for ellipse thin plate is described. The distribution of slip-line is established based on the plastic streamline. The extrusion force of plastic moulding of the steel helmet is calculated by using of slip-line method. Furthermore an applied example is given.