Research On Optimization Design Of Precision Heavy-Duty Gearbox Transmission System

With the development of high-end equipment manufacturing industry,the application of precision heavy-duty gearboxes is more and more extensive.In order to break the situation that high-end products rely more on imports,a gearbox enterprise in China has introduced a full set of German production lines.Although the product performance has improved,it is still not as good as abroad.Similar imported products.The reason why the gear transmission system is the most important component of the gearbox is the key to improve its quality.At present,the design of gearboxes in domestic enterprises mostly stays in the stage of experience design.The gearboxes designed are often not compact.Problems such as large vibration and noise.Since the mass of the gearbox is mostly concentrated on the casing,it is necessary to lightly design the gearbox body,and at the same time avoid the resonance of the gearbox and the transmission system to prevent the transmission system from failing.The working state of the transmission system can be judged according to the dynamic characteristics of the transmission system.Due to the existence of many nonlinear factors,the transmission system has very complex vibration characteristics,and the gear modification can optimize the dynamic characteristics of the transmission system to a certain extent and reduce the appearance of vibration noise.In order to solve this series of problems,it is necessary to conduct in-depth research on the light-weighting and vibration reduction and noise reduction design of the gearbox.In this dissertation,the B3SH11 gearbox is taken as the research object.Under the condition of considering the strength of the box and the resonance of the box and the transmission system,the quality of the gear box is optimized,and the static and nonlinear dynamic characteristics of the gear transmission system are analyzed.The optimization of gear topology and the influence of gear shaping on nonlinear dynamic characteristics are studied.The main research contents of this dissertation are as follows:Firstly,the natural frequency of the gear box is used as the test index,the box mass and the equivalent stress are used as the evaluation indexes.Starting from the wall thickness parameter of the existing gear box,the wall thickness of the key part of the side wall of the gear box is controlled.Factors,through the optimization of multi-objective parameters based on orthogonal test method,determine the optimal optimization parameters,the quality of the optimized gear box is reduced by about 13.9%,and the resonance between the gear box and the transmission system is avoided.Secondly,based on Romax,the static analysis of the transmission system is carried out,the strength of the drive shafts at each level is checked,and the life and wear of the meshing gears and bearings are analyzed.The simulation analysis results show that the maximum combined stress of the drive shafts at all levels is smaller than that of the materials.With stress,the fatigue loss of each bearing is less than 1,the bending strength and contact strength of the gear are within the safe range,which lays a foundation for the subsequent nonlinear dynamic analysis of the gear transmission system.Then,based on the B3SH11 three-stage cone-helical gear transmission system,considering the time-varying meshing stiffness of the gear,the meshing damping,the flank clearance,the transmission error,and the input torque and load,the centralized parameter method is used to establish 18 according to the mechanical equilibrium conditions.The nonlinear dynamic equation of the bending-torsional-axis coupling of degrees of freedom is solved by the variable-step Runge-Kutta method,and the dynamic characteristics of the transmission system are studied.Finally,based on the gear meshing principle and the Romax software,the tooth profile of the trimming gear is determined for the characteristics of the helical gear,and the shape of the gear tooth profile is derived.Then the multi-objective decision matrix method is used to determine the shape modification parameters to find the most reasonable.The optimization parameters of the 7-degree-of-freedom bending-torsion-axis coupling dynamics model of the modified helical gear transmission system are established by Simulink.The results show that the gear error is reduced by 55.6% after the gear is modified,and the tooth surface load distribution is relatively uniform.The temperature dropped by 35°C,and the vibration amplitude of the gear also decreased to some extent after the modification.