Research On Contact Analysis And Profile Modification Of Small Four-wheel Tractor Transmission Gear

Small four-wheel tractor are still very widespread application of farm power machinery in the northern of Shaanxi,Gansu and other hilly areas,noise and vibration problems of small four-wheel tractors are still plagued people,gearbox noise is one of the main sources of small four-wheel tractors,and the noise source transmission mainly from the gear. Transfer errors and meshing stiffness of noise and vibration when the gear has a direct relationship,with the improvement of the operator of the tractor comfort requirements,Thus the gear noise and vibration reduction put forward higher requirements.Therefore,in order to reduce vibration and noise during gear engagement, and without changing the basic parameters of gear, gear modification has become a very important way to reduce the noise. In this paper,with an oriental red YTO-180 small four wheel gearbox as the research object, for the carrying capacity and stability issues,the gear contact analysis were studied to explore the carrying capacity and smooth resistance of gear modification on gears, the main content and conclusions of the study are as follows: Firstly,the Pro/E software was utilized to establish parametric model of gear,and helical gear assembly without interference was achieved in combination with the principle of the gear. Secondly,the gear model is imported into FEM software with ANSYS Workbench. Based on the boundary conditions and constraints load,analyze the basic finite element analysis, including static analysis, modal analysis, transient dynamic analysis and simple transient thermal analysis and transient thermal stress analysis,combining with results obtained the variation of gear contact stress and strain. Thirdly,The main study of the impact of profile modification for gear performance finite element analysis of linear modification can be drawn,the maximum contact stress value after modification becomes 2310 MPa,the contact pressure dressing after the 726.99 MPa. Repair after profile shape due to contact area is reduced,this will help reduce the stress values change gear contact critical point,to avoid the impact of the phenomenon when the number of gear caused by the change;in addition,the maximum contact stress curve transition is smooth, in biting gnawing a position to avoid the stress concentration problems,smooth transmission gear system played a good role in helping to reduce vibration and noise, prolongs the life of gear pairs. Finally,the effect of drum shape modification on the transmission performance of the gear is studied,and the profile is analyzed and compared with the profile modification,the maximum contact stress value after modification drum reduced 46.36%,reducing the bitingengagement of stress case value is too large,improving the impact of the phenomenon contact;contact pressure decreased 20.75%. Drum shaped gear modification and end to the repair thin can reduce meshing in and out of the maximum contact stress values,so as to avoid meshing gear change in the impact of the phenomenon,improve the distribution of the load and improve the stability of the transmission,to reduce the vibration and noise.