Designing optimal geometry of the radius die for broaching cases

The object of this study is the technological process of broaching cartridge cases through a radius die on a mandrel. The work is aimed at solving the actual scientific and technical task of improving the technological process of broaching on a mandrel through a die in the manufacture of cartridge-case type forgings, which provides an increase in the stability of broaching dies. The finite element method (FEM) was used to simulate the processes of broaching cartridge cases through the die. As a result, a rational geometry of the radius die has been established. Recommendations for designing new die structures have been devised, which involve determining the rational radius of rounding of the working part of the die. The established recommendations have been verified by experimental studies. The broaching of cartridge cases through a die with a working radius surface should be carried out at relative radius R/d=3.0. In this case, stress intensity decreased by 7...17 %, average compressive stresses decreased by 8...15 %, and normal pressure decreased by 10...15 % compared to smaller rounding radii. The resulting force on the working surface of the die decreased by 40...55 %, and the radial component of this force decreased by 50 %. It was found that the working surface of the die is heated to a temperature of 750...850 °C, but the rounding radius R/d=3.0 provides a reduction in the volume of this zone by 1.5...1.9 times. The resulting relative rounding radius of the die was tested under industrial conditions, which confirmed that the broaching force for this radius is lower by 15...20 %, and the stability of such a die increased by 20 %. It is recommended to use radius dies for broaching high cartridge cases. The results could also be applied at enterprises during the production of dual-purpose parts