Tractor gearbox is the core component of the whole transmission system. The force generated by its internal gear meshing transmission will eventually be transmitted to the casting of tractor gearbox housing. If the casting of tractor gearbox housing is not strong and rigid enough, it will produce large deformation and stress under some working conditions, which will cause excessive installation error of gear shaft, further cause gear meshing error, light cases will produce a lot of noise, and heavy cases will accelerate gear wear Reduce service life and even cause gear damage. Therefore, the casting of tractor gearbox housing should have large strength and stiffness, good vibration characteristics, corrosion resistance and so on. This chapter mainly studies the structural strength and stiffness of tractor gearbox shell casting under static load, and according to the analysis results, ensure the correctness of structural optimization and the rationality of topological optimization constraints, and serve as the judgment basis of its mechanical properties after optimization.
The static analysis of the casting of tractor gearbox housing is mainly carried out. The static analysis of tractor gearbox shell casting is carried out by using HyperMesh, and the stress nephogram and strain nephogram of tractor gearbox shell casting under low speed reverse gear and first gear are obtained. During the static analysis, it is necessary to first confirm the working condition of the tractor gearbox shell casting. Considering that the transmission torque of the internal gear meshing of the gearbox is the largest in the first gear and reverse gear, we choose to analyze the stress of each bearing hole under these two working conditions. In addition, when analyzing the above two working conditions, according to the actual situation, we should also consider the influence of other parts such as engine and front counterweight on it. After completing the above calculation process, establish two working conditions in HyperMesh, apply corresponding loads and constraints respectively, conduct static calculation, and obtain the calculation results.
The analysis results show that the positions with the maximum stress and deformation appear near the three diaphragm positions of the tractor gearbox shell casting, the connection between the tractor gearbox shell casting and the engine and the connection with the rear axle housing. The maximum stress is 78.90mpa, which is less than the allowable stress of the shell material of 124mpa, and the maximum displacement is 0.06985mm. Considering that the total mass of the casting of the tractor gearbox shell is about 164.8kg and the mass is very large, it can be considered to reduce the wall thickness of the shell where the stress is small under the condition that the shell meets the normal service performance, so as to reduce the material consumption.