Study On Grinding-strengthened Surface Layer Forming And Controling Mechanisms

Grinding is a method of using abrasives as its tool to cut the surface of the workpiece, and can achieve some parts’ surface quality which meet a certain of requirements. There is mechanical force going with grinding. It makes workpiece’s material occurred plastic deformation at high strain rate condition. Finally, residual stress left in the surface layer of the workpiece. At the same time, a lot of heat is produced in the process of grinding, and some time it exceed the workpiece’s material phase transition temperature. The heat generated in the process of grinding can be used to conduct heat treatment on the surface layer of workpiece, in order to achieve a certain of thickness of rigidity layer. With the increasing of grinding speed, the abrasive impact influence on workpiece’s material will become more remarkable. Based on general grinding process in this paper, a research what affect with the hardness and residual stress of parts under the strain rate of grinding layer and temprature effect in the process of grinding.(1) Through studying theory, discussing the action between abrasive and workpiece’s material in the process of grinding is a mechanics behavior of impact. How strain rate affect force, hardness and residual stress is studied.(2)45steel had been carried out on a horizontal spindle and rectangular-surface grinder. The metallograph of the hard layer is observed with metallographic microscope, and the hardness and residual stress of surface layer after grinding were tested with hardness tester and strain gauge. The influences of cutting depth and workpiece’s feeding speed on hardness and residual stress of surface hardened layer were discussed. After observing metallograph, it found that gain of organization in the hardening region of hardened layer became thinner, the density of dislocation increased. And carbide was found in the field of ferrite. The testing research also found that with depth of cut increasing, or feed speed decreasing, the surface residual stress decreases.(3) The field of grinding temperature is numerically simulated at the use of ANSYS as analysis tool, and distribution of temperature field and the temperature-time curve of nodes along different surface depth in the process of grinding were obtained. The temperature field was simulated at different cutting depth and feeding speed conditions. The influence of grinding parameter on nodes’ temperature was compared. The depth of hardening layer was predict based on maetensitic phase transformation conditions of workpiece’s material45steel and the temperature of nodes. And compareing with experimental date, the simulation of temperature field was validated correctly.(4) The numerical simulation of heat and force coupling field of45steel’s grinding was carried using limited elemental software ANSYS. The distribution of residual stress along workpiece surface depth was obtained. The result of residual stress simulation was validated correctly through compared the distribution result of residual stress and the date which got in experiment.