| Planetary Multispeed Face Gears Transmission Device(MFGTD)is a novel Transmission Device introducing face gears into planetary multistage transmission system,so that it realizes the variety of multiple transmission ratios,and expands the speed ratio area of single-stage face gear flexibly,which provides advantages such as energy conservation and efficiency,transmission series simplification,supporting structure optimization and loading capacity increasing.This topic solves the key technical problems such as double crown tooth configuration optimization,high precision machining and load capability performace,which starts from the key theoretical problem of double crown tooth surface design of face gear and aims to eliminate meshing interference or improve transmission stability and load capacity.The meshing characteristic,contact strength and dynamic characteristic are studied by changing the meshing teeth,pressure Angle,input speed and load,and then to optimize the geometry and boundary conditions of the double crown tooth surface.The characteristic parameters of double crown with high load capacity are established through the prototype manufacturing and tooth surface accuracy detection.On this basis,aiming at improving the transmission performance and variable speed smoothness of planetary MFGTD,the study is carried out around the load sharing and shunt characteristics and transmission efficiency of planetary gear.The solving models of transmission error and transmission efficiency are setting up by the numerical simulation method,to analyze the influence of various factors on kinetic characteristics in detail.The thesis mainly includes:(1)Establishing the geometric parameter design model and the microstructure sensitivity parameter model for the double crown tooth surface structure.The gear transmission cannot avoid the influence from the design,manufacture and installation deviation,or the load deformation,vibration and unbalance loading in meshing process and so on.With the speed or load increasing,the thermal deformation or mechanical deformation of gear teeth are increased significantly,it is inevitable to appear the impact of meshing into or out,load mutation and speed fluctuation.Because of the complicated nonlinear relation between morphology parameters of crown tooth surface and dynamic response,it is needed to constructe the functional relationship between dynamic transfer error and crown quantity,to study the regularity of distribution of transmission error to determine morphology relation of crown tooth surface of face gear and sensitivity objective function with influence parameters.(2)Establishing the meshing contact relation and dynamic model of double crown tooth surface of face gears.Because of needing to match the changes of working conditions,the contact surface is always subject to periodic alternating stress in the transmission process,so that the bending and contact fatigue strength of face gear will affect the reliability.In addition,the impact caused by speed change and contact deformation caused by load change on entering and exiting of gear teeth can also affect the transmission accuracy of gear.Therefore,the contact stiffness model in the contact surface of face gears pair is also needed to establish.When constant input speed,the contact trajectory and contact area of face gear with double crown surface are studied under free idling or loading conditions.A contact dynamics model with pure torsion and single freedom degree in double crown tooth surface contact of single gear pair is set up to study,the values and corresponding rules of instantaneous meshing stiffness,meshing damping and integrated transmission error are analyzed under the conditions of crown microcosmic parameters.(3)Studying on precision and machining technology of double crown tooth surface.Aiming at improving load distribution and reducing tooth surface abrasion,the influence of load condition and cycle amount on tooth surface abrasion is analyzed.The appropriate cutters,pitch,cutter path,spindle rotation degree,feeding speed and back engagement of cutting edge should be selected for the precision machining method.The corresponding measures shall be taken in the processing technology to improve the surface performance and service life of face gear,such as the study of sand blasting,electrolytic polishing and surface coating technology.Crown tooth surface is a kind of complex surface,the curvature change of each point is not uniform.In order to evaluate the machining accuracy of face gear and extract corresponding machining errors,the tooth surface is detected by trilinear coordinates.(4)Analysising the loading contact limit and dynamic characteristics of face gears with double crown surface.Establishing theoretical calculation method based on Tooth Contact Analysis(TCA)model,Load Tooth Contact Analysis(LTCA)model and Variable Speed Interstage Impact model(VSII).The loading contact characteristic,marginal contact characteristic and stress-strain process characteristics under the change of crown quantity are studied.The VSII model is studied through adjusting the tooth surface error,then the fatigue strength and impact load,analysising various failure modes are calculated and checked.A torsional vibration model with multiple degrees of freedom is established based on the meshing and unbalanced effects of gears,to analyze the effects of dynamic excitation on the dynamic characteristics of multistage face gears,such as stiffness,error and meshing impact.(5)Studying the transmission performance of planetary MFGTD.Combining the transmission principle and transmission mechanism of MFGTD,the calculation equations of power flow and transmission efficiency are derived,the power distribution relationship between components is obtained.The static load and dynamic load characteristics of all power flow branches are analyzed.The comparison model of transmission errors is established by using numerical simulation and finite element method,the influence rule of transmission errors on key parameters and various excitations is analyzed,which provides effective reference for improving the transmission performance. |
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