Machining deformation mechanism of extra large split straight bevel gear

Super large straight bevel gear is a key component in China’s large-scale equipment. Due to the limitation of transportation and assembly of large straight bevel gear, the split structure is mostly selected in processing. According to the structural characteristics of super large split gear, the structural deformation after gear cutting is the main factor affecting its gear cutting accuracy. The existing data show that the structural deformation of the split body is mainly caused by the change of stiffness and internal pressure in the process of cutting. Mastering and predicting the deformation law caused by the change of stiffness and internal stress in the process of machining is an important problem that must be solved to ensure the cutting accuracy of the split body.

However, the existing research focuses on the optimization of machining process and the specific measures of deformation control, while the research on the deformation mechanism of split gear machining is rarely reported. Therefore, the machining deformation mechanism of super large split straight bevel gear is studied. The main research results and conclusions are as follows:

  1. The theoretical calculation model of equivalent stiffness in the machining process of split wheel blank is established. From the calculation results, it can be seen that the stiffness of split wheel blank continues to decline in the process of gear cutting, and the closer the gear cutting is to the middle position of wheel blank, the more obvious the stiffness decline of wheel blank is.
  2. The finite element model of split wheel blank with initial stress is established in ABAQUS software, and the life and death element technology is used to simulate the gear cutting processing of wheel blank. The simulation results show that the deformation mode of wheel blank is mainly bending deformation in the processing process. Corresponding to the previously calculated stiffness, it can be seen that when the stiffness of the split wheel blank decreases significantly, the corresponding deformation of the wheel blank also increases significantly.
  3. Deduce the position change formula of section neutral axis in the process of splitting wheel blank machining and the relationship between deformation curvature before and after wheel blank machining, establish the mapping relationship model of splitting wheel blank stiffness change residual stress evolution deformation, and calculate the deformation in the process of wheel blank machining using the mathematical model. After comparing the calculation results with the results of finite element simulation, it shows that the results obtained by the two calculation methods are highly similar, The correctness of finite element simulation is verified.
  4. Change the parameters of the split wheel blank, and carry out the finite element simulation processing for the wheel blank of different sizes. The simulation results show that the larger the thickness of the split wheel blank is, the smaller the deformation is, and the smaller the length is, the smaller the deformation is. Through the collation and data analysis of multiple groups of simulation results, the appropriate wheel blank size can be selected considering the economic cost and assembly difficulty, so that the structural deformation of the split wheel blank can be controlled.
  5. Use the cam module of UG to simulate the rough and finish machining of the wheel blank respectively, and generate the corresponding NC machining program through the post-processing function of the software. After the NC code is imported into the machine tool simulation software and the simulation is correct, the gear cutting is carried out in the actual machine tool and the actual deformation of the wheel blank is measured. The experimental results are compared with the simulation results to further verify the correctness of the finite element simulation and mathematical model.