Research On The Behavior Of Surface Work Hardening In High Speed Cold Rolling Forming Under The Action Of Non-uniform Thermal Coupling

High-speed cold rolling forming technology, as a kind of efficient, green and high forming precision plastic forming technology, has become one of main processing methods of some key parts. It is used widely in the industries of automobile, aviation, machine tools, so the cold forming technology has a broad application prospect. The high speed cold forming is more used for function surface of precision parts. Its quality directly affects the performance level of products, so the study on behavior of work hardening in high-speed cold forming has an important guiding significance for practical engineering application. This paper adopts the method of combining theoretical analysis, simulation with experimental to research the surface work hardening behavior in high-speed cold rolling forming, in order to improve the using properties and surface quality of the product to provide theoretical basis.The work hardening in the high speed cold rolling is stated in the paper. The high speed cold rolling coupled thermo-mechanical forming mechanism of high-speed cold rolling processing and hardening heat coupling mechanism are discussed. Work hardening in the performance of the micro and macro aspects are analyzed, and work hardening model of macro and micro is established. The motion principle and characteristics of cold rolling is analyzed, and the simulation model is established. Based on high speed cold rolling forming mechanism of work hardening under the action of thermal coupling, the influence of high speed cold rolling forming process parameters and other related factors on the microstructure and work hardening are analyzed through the simulation. Experiments of XRD, SEM, microhardness test related to work hardening in high-speed cold rolling processing were carried out under the different cold rolling conditions. A mathematical model of surface hardness based on dislocation density is established. The influence of different cold rolling conditions on the different parts of the work hardening workpiece are analyed.In the weakening effect on temperature field and reinforcement effect of stress field, the work hardening is interaction between dislocation and dislocation. Dislocation density throughout the whole process. Based on work hardening mode of macro and microscopicl, the relation of dislocation density, strain and temperature with the rate of work hardening are analyed. Based on theoretical study, combined with the simulation and experimental analysis, with the rolling wheel speed increasing, the heat generated by the rolling process, the temperature increasing, the degree of grain refinement in the process of cold rolling, the more obvious, the greater the hardness, the more obvious work hardening phenomenon. With the increase of feeding within a certain range, The greater the feed, the greater the workpiece metal grain is refined, the greater the hardness, the greater the work hardening phenomenon is more obvious. With the increase of temperature, the dislocation density decreases, half width and surface hardness decrease. At the same temperature, with the increase of strain rate, the half width increases and the dislocation density increases. The surface hardness is increased. To some extent, metal organization are refined, and fibrous organization of a spline root department distributes along the tooth profile forming direction. Spline root obtains good improvement, and the performance of the workpiece is greatly improved. Mathematical model of surface hardness based on the dislocation density is confirmed through the experiment, which can be a better research on work hardening behavior from the microscopic view.