| Mining excavator is an important equipment of Mechanical system.With the development of mining excavator in the direction of large-scale,the requirements of dynamic characteristics of structural parts and transmission system are higher.Lifting mechanism is a key component of mining excavator.It is required to have stable dynamic performance under stochastic,vibrational and impulsive loads.To improve the operation security and stability of lifting mechanism,this thesis firstly analyzes the dynamic performance of gear transmission system,further optimizes its dynamic performance.The primary contents in this thesis involve:(1)The internal incentive and external incentive of gear transmission system in the lifting mechanism for WK-55 mining excavator are analyzed.According to the gear parameters of WK-55 mining excavator,the parameterized model of gear transmission system is established using command chain APDL in the ANSYS software based on the involute principle.The time-varying meshing stiffness is calculated by combining finite anlysis method and BP neural network.The results are compared with Ishikawa method and ISO method.(2)The dynamic meshing force of gear transmission system is analyzed.The lifting gear reducer adopts two-stage symmetric gear drive structure in this paper.It is composed of helical gear transmission in the first stage,and spur gear transmission in the second stage respectively arranged on the left input and right input.The 3-D model of lifting gear transmission system is firstly estabilished.Then,the dynamic meshing forces of gear transmission are analyzed using ADAMS software.(3)By using Lumped-mass Method,the dynamics model of gear transmission system model that include time-variant meshing stiffness and time-variant load is established.And its dynamic transmission errors are obtained by Harmonic response method.(4)The modal analysis model of lifting gear transmission system for WK-55 excavator based on finite element method is established.And the modal analysis results are compared with the excitation frequency.Further,the natural frequency of the gear system are analyzed under different gear transmission parameters.(5)A parametric finite element model of the gear transmission system for shaft spur is created by command chain APDL,and the contact stress is analyzed under different number of teeth,modulu,shaft length and rotation speed.(6)The dynamic performance optimization design model of the gear transmission system is formulated,and the optimization results are solved and compared with the initial design. |
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