Study On The Forming Process And Microstructure Evolution On Cross Wedge Rolling Of The Shaft Parts

Shaft parts are widely used in current industrial fields, it often bears a great load, friction and wear in the process of use, it requires high performance and quality. In response to the lack of resources in the current situation, for the purposes of energy and materials saving, cross wedge rolling technology come into sight because of the advantages of highly efficient and material saving, widely used in automotive, construction and other fields of shaft parts production. Cross wedge rolling material utilization rate is more than 90%, greatly reduced the cost of production.Although cross wedge rolling technology has been widely used in actual production, there are still some problems, some factors of uncertainty in the design process. First, cross wedge rolling for the design is complex, large interaction between various process parameters, process parameters determined often depend on experience. Secondly, the central defects is easy to occurred during the forming process, The causes of defects have some relationship with plastic forming mechanism, and the reasons is hard to find out with experience, it bring some difficulties in the practical application. So it has important practical significance to study on deformation mechanism of cross wedge rolling for shaft parts and fine design of process.In this paper, taking a type of intermediate shaft gearbox as the research object, according to the principle of cross wedge rolling, to design the cross wedge rolling process of transmission shaft by using the finite element method and physical experiment. By means of finite element method, the changes of temperature field, strain field, force energy parameters and austenite grain size were studied and analyzed, and the prediction of grain size change during the forming process was predicted. Research on the loose defects in the center of the forming process, production mechanism is analyzed, and explore the effects of different process parameters on the quality of the core section, providing an important reference for cross wedge rolling mold design. Specific contents are as follows:(1) According to the theory of cross wedge rolling, The process design for cross wedge rolling shaft of a certain type of gear box and numerical simulation of cross wedge Rolling Process is conducted. Analysis of forming process temperature, equivalent strain field and force parameters variation with time, to ensure the reliability of the design scheme.(2) The loose defects in the core of cross wedge rolling and its mechanism is studied. The effects of various process parameters on the quality of the core section forming is analyzed by the finite element method, and the effects of relevant factors for heart defects is Obtained.(3) According to the austenite grains grow physics experiment, the austenite grain growth evolution model of 20CrMnTiH steel is established. Combined with data provided in the literature, considering the dynamic recrystallization and grain growth mechanisms, austenite grain size evolution in the cross wedge rolling and isothermal normalizing process is predicted.