Sukhorukov S. Improvement of technology of the flat cross-wedge rolling of step cylinder purveyances

Research object is plastic deformation process during flat cross-wedge rolling (FCWR). Research goal is to achieve higher quality of step cylinder purveyances on the basis of the development of the methods for stressed state calculations and working out recommendations on the improvement of FCWR technology. In order to achieve the goal, methods and laws of the solid environment mechanics were used as well as those of mathematical and applied plasticity theory and of the applied deformability theory. Scientific novelty of the obtained results consists in the following: numerical mathematical model of the step cylinder purveyance stressed state in the process of FCWR was developed that makes it possible to determine the influence of the process parameters on the forming limit and technological inheritance; for the first time a regression dependence of the utilized plasticity resource influence on the instrument parameters and rolling temperature conditions was obtained, which enables the purveyance quality prediction; on the basis of the known deformability criteria, the criteria are proposed that make it possible to evaluate the temperature influence on the value of the utilized plasticity resource during FCWR; it was determined how the western part geometry and the length of the instrument calibration section in FCWR with reduction degree of 1,8…2,0 influence the probability of macro cracks to appear in axial zone of the purveyance. Practical importance of the obtained results: methods were developed for the purveyance deformability evaluation during plastic deformation under high temperatures in the process of FCWR for reduction degree of 1,8…2,0 using the proposed deformability criteria; the complex of software tools was developed to calculate the trajectory of the random point loading in the space of three dimensionless indices of stressed state, which makes it possible to evaluate the process parameters influence on the forming limit; new test purveyance scheme was developed in order to investigate the kinematics of the purveyance metal flow during FCWR; engineering procedure is proposed for the selection of FCWR process main parameters that enable provision of the required level for the utilized plasticity resource value in the dangerous zone of the purveyance; methods and software tools were developed for automatic calculation of the instrument design parameters and technological modes for cylinder step purveyances manufacturing using the method of flat cross-wedge rolling. Implementation degree: the results of the thesis are given for implementation at "VAZ" open joint-stock company (Vinnytsia) and are introduced into the educational process at the department of Machine-building technology and automation of Vinnytsia National Technical University. Application field - machine-building.