Research On Cylindrical Gear Tip Rounding With Worm Grinding Wheel

Gear tip rounding is one of the most important machining techniques in the field of aero-engine.It can effectively avoid the damage of meshing surface caused by the collision of the edges and the stress concentration during heat treatment.Thus reduces the meshing noise,enhances the service life.However,the current tip rounding process has the residual problem of tip cusps.In addition,too small radius of tip rounding of the gear will lead to dresser interference and difficult processing.Therefore,small size tip rounding is still manually polished.It is inefficient,waste of manpower and time,and the gear quality is difficult to guarantee.For this reason,this paper puts forward the method of worm grinding for gear tip rounding.The method includes simple grinding method machining the tip rounding with large radius and multi-approaching method for machining the tip rounding with small radius.The main work of the paper can be summarized as follows:(1)The kinematic geometry relationship between gear and worm grinding wheel and their 3d models were established.Taking involute cylindrical helical gear as an example,the end face profile equation of the gear tip rounding was derived and the surface equation was obtained by using helical transformation.The discrete points of the worm profile were calculated by solving the meshing equation.The model of worm grinding wheel was obtained by 3d modeling software.(2)The simple grinding method for machining rounded corner of gear tip was analyzed.Aiming at the problem that traditional method of solving worm profile is limited by the discrete precision,an equidistant offset method of worm grinding wheel profile was proposed to solve the rounded corner of gear tip.The equidistant offset characteristics of conjugate curves were analyzed,and the equations of equidistant offset line of rotation curve were derived.The calculation results of this method were compared and verified with the profile points obtained from the meshing equation.The grinding wheel dressing method was designed and the point dressing error was analyzed.(3)The multi-approaching method was analyzed.The gear shape change rule of the translation grinding wheel was explored by solving the meshing equation.The offset of the grinding wheel and the gear surface after the translation of the grinding wheel were solved.The addendum rounding obtained by approximation was calculated and plotted by Matlab.The approximation error of multi-approaching method was analyzed and fitted.The approximate parameters were optimized by the simplex method.(4)The machining simulations of the simple grinding method and the multiapproaching method were carried out.The Simulation was based on bool operation function of 3d software.It is mainly used to verify the worm profile of the simple grinding method and the offset of the multi-approaching method.By solving the machining error of simulation results,it showed that the worm profile is solved correctly,the multiapproaching method is accurate and the method of continuous generating grinding for gear tip rounding is feasible.(5)The functional software of continuous generating grinding method for gear tip rounding was developed.The software is based on SINUMERIC 840 Dsl numerical control system,and HMI interface was written by C++ language.The input of project parameters,the generation of worm profile and dresser track were realized.NC program includes grinding program and various functional program.It lays a foundation for the next practice of gear tip rounding.