Research On Microstructure Evolution Of Cross Wedge Rolling Asymmetric Shaft Parts And Non-remnants

With the development of the transportation industry, the demand for large asymmetric shaftparts along the length is increasing and the demand for the quality of shaft parts especially itsmechanical properties is also increasingly high, which makes study focus of the rolling of shaftparts gradually change from model control into coordinated control of model and property.Therefore, how to ensure the stability in the rolling process and the density of organization afterrolling are a series of key scientific and technological problems urgently needed to solve for crosswedge rolling asymmetric shaft parts. At the same time, the finished product rate of the traditionalplastic forming process in the context of a series of new technical applications is increased, whilethe finished product rate of cross wedge rolling is always stagnant (80%-85%) because ofremnants, seriously weakening its market competitive advantage. Therefore, how to achieve lesscutting or no cutting after the completion of the cross wedge rolling and further improve materialutilization is the key to promoting cross wedge rolling technology promotion. In summary,increasing the mechanical properties and the finished product rate of cross wedge rollingasymmetrical shaft parts has important theoretical significance and application value.The paper adopted research methods with a combination of finite element numericalsimulation and rolling tests and made a study of the asymmetrical rolling microstructure evolutionand non-remnants rolling technology. It mainly undertook the following matters:1) on the basis ofthe asymmetric rolling, design and develop plain wedge; while inhibiting axial movement andensuring sTab rolling, optimize the rotation conditions and expand the range of choice of wedgerolling process parameters;2) starting from the aspects of the heat and force in the metaldeformation process and microstructure evolution, make simulation calculation on the formingprocess of cross rolling wedge asymmetric shaft parts by making use of the rigid-plastic finiteelement model with heat, stress and organization mutual coupling to obtain the distribution oftemperature field, strain field and high temperature austenite particle size of the work piece afterrolling, and by comparison with relevant field variables of symmetrical rolling, clarifymicrostructure evolution of cross wedge rolling asymmetric rolling;3) based on the analysis of theconcave heart formation mechanism, propose forming ideas of extruded cross wedge rolling non-remnants rolling; simulate non-remnants rolling process of oil pump shaft through the creationof the finite element model of the extruded cross wedge rolling; obtain optimal mold structure andprocess parameters of non-remnants rolling and improve the one-off finished rate of finished crosswedge rolling shaft parts to about95%;4) make use of non-linear finite element to establish arigid-plastic finite element model with deformation-heat transfer-microstructure mutual coupling;obtain the distribution of temperature field, strain field and austenite particle size in conditions ofthe extruded cross wedge rolling, and set forth the evolution of the microstructure of the crosswedge rolling non-remnants rolling;5) develop a set of oil pump shaft non-remnants rolling molds;through H630cross wedge rolling, carry on the rolling experiment and metallographicexperimental of finished products after rolling; compare and analyze the experimental results withfinite element simulation results and verify the reliability of simulation results.The results of this research are of important scientific significance and value of engineeringapplications to innovate cross wedge rolling shaft parts rolling process, enrich and perfect wedgecross rolling asymmetric rolling theory, reduce production costs and improve the quality of therolling products.