Analysis And Verification Of The Fatigue Test Data Of Rack For The Three Gorges Ship Lift

The Three Gorges ship lift is an important part of the Three Gorges Project,it can shorten the time of ship crossing dam through the ship lock over 3 hours to 40~60minutes,which is an important navigation facility for the passenger ship to pass the dam quickly.The reliable operation of ship lift is an important guarantee for ensuring passenger ship passing through dam safely and rapidly in the Three Gorges Project,which is of great significance for improving the navigation quality and the ability to navigate through the dam.The Three Gorges ship lift is the largest scale in technology and the most complex ship lift in the world with the characteristics of large lifting weight,high lifting height,large fluctuation of upstream water level and fast change of downstream water level and so on.The Three Gorges ship lift adopts gear-rack climbing type,the processes of carge and induction hardening are complicated,and the quenching residual stress is difficult to control because the hardened layer of the tooth surface reaches 9mm.In order to ensure the long-time safe operation of the ship lift,it is very necessary to carry out the fatigue life test of the rack.The gear-rack test bed for the Three Gorges ship lift is the special test device developed for the rack fatigue test of the Three Gorges ship lift.The life test that has been carried out accumulates about 98 days,the number of stress cycles up to4.22?10~5.During the test,the measuring and control system of the test device automatically monitors the speeds and torques of the input shaft and the output shaft,the stress and strain of the tooth root and the number of cycles and so on,which collects a set of data every 0.1 seconds.A single operating period of test device is 10 seconds,every 20 seconds is a test cycle period,the measurement system saves one data file every 300 cycles,each data file has 60 thousand sets of test data,the whole experiment accumulates about 7.1 billion data.Therefore,the analysis and processing of data are very large workload.For such massive test data,the data analysis and the accuracy verification are particularly important,in particular,the data change is large and the analysis is more complicated during the reversing,changing speed and changing load period of the test device.The test process requires frequent reversing,the effects of the gear meshing backlash,the shaft elastic torsional deformation,the elastic deformation of gear tooth and other factors result in the fluctuation of the output rotational speed and torque of the test device.Therefore,it is necessary to theoretically analyze the impact of the gear meshing backlash and the shaft elastic torsional deformation and other factors on the rotational speed,and through the theoretical calculation of the power loss of each component of experimental device to get the transmission efficiency of the whole transmission system,and compared with the test efficiency.Thereby the mutual verification of the theoretical calculation value of the experimental data and the measured values of the test device is realized.The main researches and conclusions are the following:(1)The operating principle,the control strategy,the stress and strain monitoring position of tooth root of rack and the test data acquisition system of the gear-rack test bed for the Three Gorges ship lift are analyzed,which laid the foundation for the analysis of the test data.(2)The determination method of the stickup position of strain gauge of the rack tooth root is studied,the change rule of stress of rack tooth root during the testing process is analyzed.Through the theoretical calculation and comparison of the input and output speed of the driving gearbox of the test device,the change rule of speed and torque are obtained.The effects of the gear meshing backlash,the shaft elastic torsion deformation and other factors on the rotational speed are analyzed.(3)The gear meshing backlash and lost motion calculation model and the shaft elastic torsion deformation calculation model are built,the effects of the gear meshing backlash and the shaft elastic torsion deformation in the process of test on the rotational speed of the test device are analyzed.Through the comparison and analysis with the experimental data,the consistency of the calculated results and the experimental data is shown,and the mutual verification of the test results and the theoretical calculation data is realized.(4)The calculation models of gear meshing power loss,bearing power loss,oil charming power loss,oil seal power loss and wind drag power loss and others are established.The effects of gear teeth number,modulus,pressure angle,rotational speed and torque on gearbox transmission efficiency are analyzed.(5)On the basis of the calculation model of gearbox efficiency,the transmission efficiency of the driving gearbox,gear-rack driving,driven gearbox of the test device for the Three Gorges ship lift and the transmission efficiency of the whole test device in changing speed,changing load and test period are studied,and compared with the transmission efficiency obtained by the test data,the mutual verification of the test data and theoretical calculation value of transmission efficiency is further realized.On the basis of the above,the power consumption of the test device during the whole test is calculated.(6)The transmission efficiency of driving gearbox(reducer)and driven gearbox(increaser)are compared and analyzed,the conclusion illustrates that the transmission efficiency of the driven gearbox is slightly lower than that of the driving gearbox,and the main reasons are analyzed.