International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The results of finite element modeling of a new method with an increased metal processing level were considered. The improvement of the drawing process was achieved by changing the usual scheme of metal movement during deformation, which made it possible to achieve large strains compared to the standard drawing scheme. It is established that step drawing has the advantage of an increased processing level, but it leads to the formation of an inhomogeneous gradient strain.

On the basis of review of last developed combined metal forming processes the new concepts of severe plastic deformation combined processes aimed at further improving the deformation performance are proposed. The presence in all three proposed variants of the ECAP scheme will allow deforming without significantly changing the initial dimensions of the workpiece.

Cold forming process in the plastic domain of deformation causes strain hardening in the formed material. Strain hardening can be used for practically all metals and alloys to increase most of mechanical characteristics, however ductility and some others are reduced. In the paper experimental researches of the influence of effective strain on change of main mechanical characteristics such as tensile strength, yield strength, impact toughness, and some other characteristics of cold formed material were carried out and analyzed.

The results of the experiments are presented in the form of graphs. Special mathematical models for determination of different properties were obtained. These models are especially helpful for prediction of mechanical and other properties of a cold formed material. Knowing the material properties and their changes during the cold forming processes is very important for quality of the product and for planning the right technology of the forming processes.

By using visioplasticity method the velocity field can be determined experimentally, and then the stresses can he obtained analytically from these experimental measurements. That means, strain rates and strains are calculated directly from the velocity field while the stress distribution is calculated from an analytical solution of the equilibrium equations and the constitutive equation relating the stress and strain for the material. This method can also provide detailed data of the pressure distribution on the die surface, which is important in the design of the die profile. In the paper cold forward extrusion through a conical die is illustrated by extruding copper alloy specimens with inscribed grid lines. Stress state distribution in plastic deformation region was analyzed using the visioplasticity method. From the flow lines of each element, the velocity and the strain rates are obtained. Finally, the stress components are calculated from the equilibrium and plasticity equations.