Usatyuk D. Improvement of deforming process and development of forged pieces with enhanced precision by using the finite element method

In the dissertation the enhanced mathematical model of elastic-plastic material with thermo-mechanical hardening was developed and settled a universal approach to mathematical description of materials of billet and die. The investigation procedure of stress-strain conditions at hot forging is reduced to solution of nonstationary nonlinear coupled thermal-structural problem by the finite element method. The technique was developed for solving of this problem in which stress-strain conditions of a billet determined with taking into account mechanical properties of material that are subject to change under the influence of temperature, strain degree and strain rate. For increasing of geometrical precision of forged pieces the efficiency function that connecting geometrical precision with the non-uniformity of stress-strain conditions of forged piece at hot forging was developed. The technique for evaluation of stability of plastic equilibrium of forged piece points with using of stress-strain conditions allows for evaluation quality of forged pieces at the technology development stage. It was developed the dependence that connecting the durability of die with thermal and structural conditions and fatigue strength of die steel. The developed forged pieces were implemented to manufacturing at JSC KKZ "Centrokuz" with economical effect of 122960 grivnya per year.