Research On Modification Technology Of Rocker Arm Planetary Transmission Gear Based On Thermo-elastic Coupling

With the rapid development of coal mining mechanization,my country’s annual coal output has continued to hit new highs,and the proportion of thin coal seams in major mining areas has increased.The market needs thin coal seam shearers with high power density,high reliability and high efficiency.The rocker arm planetary transmission gear is a key transmission component at the end of the shearer,and its overall temperature rise,transmission accuracy,stability,and uniformity of load distribution seriously restrict the efficient mining of high power density shearers.Gear modification based on traditional elastic mechanics cannot effectively improve the transmission performance of high power density rocker arm.Therefore,it is necessary to fully consider the thermal effect of gear transmission on the basis of elastic mechanics,using a combination of theoretical numerical calculation and finite element simulation analysis,based on the principle of gear meshing,Hertz contact stress,vibration modal analysis,Ishikawa stiffness model,thermodynamics,Basic theories such as statics,systematically study the contact load,meshing stiffness,body temperature field,and static characteristics of the thermoelastic coupling contact meshing of the planetary transmission gear,and design a refined modification scheme based on the thermoelastic coupling contact deformation.The main research contents of this paper are summarized as follows:(1)The parametric model of the rocker arm planetary transmission gear system was established in the three-dimensional software,the coordinates of the actual meshing curve were normalized,and the meshing was obtained by using the Hertzian contact theory and finite element simulation analysis methods respectively.Contact stress distribution law of gear pair;based on the equivalent tooth profile method of Ishikawa model,the distribution law of flexibility and meshing stiffness of a pair of gear pairs is explored,which lays the foundation for the solution of the temperature field load boundary of the body.(2)Using the numerical analysis method and based on thermodynamic analysis,an accurate model of the temperature field of the gear meshing transmission body is established,the influence of various factors on the temperature field is studied,and the average heat flux density and the distribution curve of the convective heat transfer coefficient of each part are drawn.Using the method of finite element analysis,the body temperature of the thermal balance of the gear is obtained,which exhibits a "convex" distribution along the meshing curve,and the temperature gradient in the direction of the tooth width changes greatly.The prerequisite for the thermal elastic sequential coupling is obtained.(3)On the basis of establishing the steady-state temperature model of the gear body,through the finite element simulation analysis method,the analysis results based on the thermo-elastic sequential coupling are obtained,and the Von Mises stress and deformation of the gear under pure elastic deformation and thermal deformation are studied.The law verifies the necessity of thermal-elastic coupling analysis of planetary transmission gears.(4)The tooth profile,tooth direction modification principle and modification formula of spur gear are expounded,and the tooth profile and tooth end trimming design based on traditional empirical formula are briefly introduced.Focusing on the thermalelastic coupling contact analysis,the tooth profile modification and drum modification design are carried out,and the modification curve conforming to the actual working conditions is obtained.(5)By selecting 4 types of modification design inspection indicators,numerical calculation and finite element simulation analysis of three modification design schemes are carried out,and it is verified that the modification design based on thermo-elastic coupling contact analysis in this paper is superior to the traditional empirical formula.The rough modification design is better than the design without modification,which provides technical support for the modification of planetary gears in the future.