Mesh Characteristics Analysis Of Multi-stage Planetary Transmission Of Jack-up Offshore Platform Gearbox

With the increasing consumption of non-renewable energy sources,the scale of exploitation of marine LPG resources is expanding.The offshore platform lifting gearbox is an important part of the self-lifting offshore platform lifting device.The planetary gear train is the main structure of the gearbox.The meshing characteristics of the transmission system have a very important influence on its carrying capacity,life and vibration and noise dynamic performance,so the research on the planetary meshing performance has attracted much attention.In this thesis,the four-stage NGW planetary transmission of the lifting gearbox is taken as the research object.Based on the analysis of the transmission principle and strength check,the meshing analysis model of the planetary transmission system is established,and the meshing characteristics of gear pairs at all levels are calculated and analyzed,and the effects of working conditions,installation errors and gear micro-modification on the meshing characteristics are thoroughly studied.The research results have important theoretical significance and engineering for improving the comprehensive performance of the gearbox.The main content of the dissertation is as follows:(1)Analyze the structural characteristics and transmission principles of a four-stage NGW planetary transmission gearbox of an offshore gear hoisting gearbox,and check the strength of key components.On the basis of considering the deformation of the shaft,the stress analysis of the sun gear shaft and the output shaft at all levels is performed,the fatigue strength coefficient and the static strength coefficient are calculated,the strength check of the gear pairs at all levels is based on the ISO6336 standard,and the life of the main bearings in the system Calculation.The results show that all key components of the system can meet the strength design requirements.(2)Establish the meshing analysis model of the transmission system based on MASTA professional mechanical software,calculate and analyze the meshing stiffness time-varying value,mean value and transmission error time-varying value,peak-to-peak value under normal lifting conditions,and perform Fourier transform on the transmission error 15 th order amplitude and phase analysis research.The results show that the mean value of the meshing stiffness of the internal ring gear-planetary gear pairs at all levels is larger than that of the sun gear-planetary gear pairs;the time-varying value of transmission error and the peak-to-peak value increase gradually,and the maximum amplitude after Fourier transform appears in the first order.(3)The influence of input power on the meshing contact force and dynamic bearing force of the gear pairs of the system under different working conditions was studied;under the ideal assembly conditions and when the radial installation error and tangential installation error acted alone,the system Variation of load factor.The results show that the meshing contact force increases step by step and the frequency domain peak appears at the meshing frequency domain of the gear pairs at all levels;under ideal assembly conditions,the load sharing coefficients of each level decrease step by step,and the tangential installation error has a The effect is obvious,and the high-speed grade is more sensitive to its changes,and the effect of radial installation errors is almost negligible.(4)Analyzes and calculates the gear micro-repair parameters to determine the required gear meshing misalignment,and proposes a combined modification program for tooth modification(crowning)+ tooth modification(linear modification and tooth tip modification).The influence rule of shape modification on transmission error and tooth surface load distribution is obtained.The results show that after modification,the peakto-peak transmission errors of gear pairs at all levels are reduced and the fluctuations are smoother;the contact area of the tooth surface load is increased,the contact area is more reasonable,the distribution is more uniform,and the maximum contact stress value is also reduced.