Research On Machining Method And Surface Accuracy Of Micro-segments Gear Based On Fractal Theory

At present,China has become a big manufacturing country,but many core components and technologies of many mechanical and electrical products still rely on foreign countries,such as robot reducer,automatic transmission,bullet train transnission system,etc..Therefore,there is great theoretical and practical value to study the problem of high-end gears.In this paper,a new gear,the micro segment gear is selected as an object and is studied to solve some theoretical and technical problems thaht affect its popularization and application.First is the systematic analysis of the differential geometry and the meshing principle,and by referring to the content of the traditional gears,the design method and the calculation methods of meshing characteristics of the micro segment gear are improved,so the design of a more precise micro segment gear transmission can be obtained.The second,according to the meshing feature that the micro segment profiles are a concave curve to a convex curve,and traditional stiffness and contact stress calculation methods are not applicable,the fractal geometry theory is introduced to study the machined surface roughness,stiffness and precision of gear surface.Then the relationship between processing parameters and roughness and fractal dimension is found,the relationship between and calculation method between the gear roughness and fractal dimension are established,and the micro segment gear stiffness calculation formula is given.Thus,the calculation of the stiffness and contact strength of the micro segment gear is solved,and the influence of the machining accuracy can be considered in the design stage,thus the design accuracy can be improved and the product development cycle can be shortened.The third,aiming at the lack of high precision machining methods of micro segment gears,the formula needed to process micro segment gear is derived.Through the research and analysis of WEDM method,the method and technology of machining micro segment gear with higher precision by wire cutting are put forward.At the same time,referring to the involute gear grinding process and modification technology,the method and process path of micro segment gear grinding by the principle of modification are put forward.Thus,the machining problem of high precision micro segment gear is solved.The fourth,considering the lack of research on the surface accuracy of the micro segment gear,the most necessary index of the profile surface of the micro segment gear is put forward.Based on the existing roughness and gear measuring instruments,the measurement methods of tooth profile error and surface roughness of micro segment gears are established.At the same time,the relationship between the fractal dimension and the gear stiffness is found by analyzing and calculating the surface measurement data.It is proved that the micro segment gear has higher stiffness and contact strength than the involute gear.The fifth,the static test rig of gear reducers,the gear static strength test bench and the dynamic strength test of gear reducers are designed and built,and they are used to test the the involute gears and the micro segment gears,including the reducers,processed by the high precision wire cutting and the grinding.The results show that the micro segment gear and its reducer has higher slewing accuracy,strength and efficiency than the corresponding involute gear and reducer,and the their force and motion are more stable.It is proved that the micro segment gear on the whole superior to the involute gear,and it is also proved that the design of micro segment gear system,the calculation formula,processing method and the measurement method established in the paper are correct and feasible and practical value,will be an important role for promoting application of micro segment gear up.