Research On Vibration Characteristics Of Double-helical Gear With Multi-backlash Based On Tooth Surface Friction

Double-helical gear plays an important role in industrial transmission machine.With the development of modern large-scale industrial machines facing high precision,high reliability and low noise,vibration characteristics have become a main reference index to reflect the property of double-helical gear.On account of the mechanical requirement of double-helical gears are intricated and changeable,the dynamic properties of double-helical gear system will be more difficult to predict considering the effect of tooth surface friction during working.The existence of axial dynamic meshing force of double-helical gear will not only make the system have torsional vibration,bending vibration and axial vibration,but also cause torsional pendulum vibration.Therefore,it is particularly important to establish a more realistic double-helical gear model.Taking the double-helical gear as the target,the exact model is built,and the nonlinear characteristics is studied.The particular research task are as follows:The pure torsional dynamic model of double-helical gear pair is established.The solution steps of incremental harmonic balance method are inferred.The frequency response characteristics of double-helical gear system under constant backlash and dynamic backlash are solved by it.The solution results are contrasted by Runge-Kutta method.The effects of stiffness,damping,static transmission error and external load excitation on the amplitude frequency characteristics of the system under constant backlash model and dynamic backlash model are studied.Considering the excitation parameters of the helical gear pair at both ends and the elastic support of the intermediate shaft,a bending-torsion-shaft-pendulum coupling model of 24 degree of freedom double-helical gear is established.and by applying Newton’s second law,the differential equations are established.The effect of excitation parameters such as stiffness,damping,error and external load on the amplitude frequency characteristics of the system under different backlash is investigated thoroughly.On the basis of meshing characteristics,the function of tooth surface friction is investigated thoroughly.The bending-torsion-shaft-pendulum coupling model and the torsion model of double-helical gear considering tooth surface friction are built.The nonlinear vibration characteristics of double-helical gear system with or without tooth surface friction and with different tooth surface friction calculation models are compared and analyzed.The vibration test bench of double-helical gear is built.The relative vibration acceleration of double-helical gear system at distinct speeds and distinct backlash conditions is gauged by applying acceleration sensor.The vibration acceleration spectrum of the double-helical gear system is obtained by using YOUTAI data processing software,and the theoretical results are contrasted with the test data.It is found that the double-helical gear system has nonlinear characteristics such as main resonance response,subharmonic response,jump and multi-value solution.Compared with constant backlash,changing parameter value under dynamic backlash can make further efforts to regulate the nonlinear vibration of double-helical gear system.The raise of constant backlash will increase the amplitude of vibration displacement,but has little effect on the system state.The tooth surface friction has a certain damping effect,which can decrease the displacement on the meshing line,but does not change the meshing impact state.The inhibitory effect of friction is different in different dimensionless meshing frequency intervals.The test measurement data verify the theoretical numerical simulation results.