Research On Distortion And Control Of Involute Internal Spline Gear Heat Treatment

Heat treatment is one of the important processes of gear machining,whereas the carburizing and quenching is the key link to improve the hardness,strength and wear resistance of gear surface.Heat treatment in improving the mechanical properties of the gears also brought about the deformation of the gear problem.That is commonly used in gearbox of involute internal spline gear after carburizing and quenching in deformation,and the deformation size have a great influence on gear transmission accuracy.Therefore,the gear in the transmission will produce noise and abnormal sound,even reduce the service life.In this dissertation which based on the diffusion kinetics,principle of heat transfer and thermo-elastic-plastic theory,the process of carburizing and quenching of a type of involute internal spline gear,which was to be produced,was studied.In the analysis results,the regularities distribution of carburized layer concentration,temperature field,stress field and so on were predicted and studied.In addition,in this dissertation it also studied the deformation characteristics of the gear,and a scheme to control the gear carburizing and quenching deformation is been put forward.The specific work of this paper is as follows:(1)In this dissertation discussed the heat treatment technology and its development status.Based on the finite element analysis of heat treatment,a numerical model of the involute internal spline gear was established,including the selection of various parameters,the treatment of latent heat of phase change,grid division,the initial and boundary conditions and so on.And the accuracy of numerical calculation is verified.(2)The carbon concentration distribution of carburized layer in involute internal spline gear was investigated.Additionally,the distribution of temperature field,microstructure field and stress field in the whole carburizing quenching process were also analyzed.In the dissertation,based on the simulation results,the temperature distribution of the gears in the heat treatment process and the distribution of stress and stress in the gears after carburizing and quenching were studied.The dissertation also studied the plastic deformation of the gear under the action of thermal stress,the combined stress.The gear deformation of the originalcarburizing and quenching process were measured: the plane warping was 0.036mm;the taper of the internal spline hole was 0.056mm;the expansion of the top,middle and bottom of the addendum was 0.100 mm,0.093 mm and 0.097 mm respectively.(3)In the follow-up work of the dissertation,the influences of carburizing layer thickness,carburizing temperature,quenching temperature and quenching medium temperature on the carburizing quenching deformation of the gear were studied respectively.According to the rule of the influence of each factor,the scheme of controlling the deformation of heat treatment was been put forward.The results show that the reduction of carburized layer thickness,carburizing temperature and quenching temperature can effectively reduce the deformation of gears under the condition of ensuring the mechanical properties of gears.In the KR468 C quenching oil temperature range 70? ~ 120? to improve the oil temperature.It also plays a role in controlling the deformation of gear carburizing and quenching,but the effect is not obvious.On the basis of the heat treatment process of the original design,the final heat treatment parameters were determined with carburized layer thickness of 0.8mm,carburizing temperature of 880?,quenching temperature of 820?,quenching medium temperature of 100?.