Study On The Model Design And Key Technologies Of Economic And Functional CNC Milling Machine Tools Of Curved Tooth Bevel Gears Used On Vehicle Driving Axles

Curved tooth bevel gears,consist of spiral bevel gears(and hypoid gears)with tapered tooth depth by Gleason and cycloid bevel gears with equal tooth depth by Oerlikon,are considered as the key parts of the driving axles for vehicle,whose standards of manufacture are closely related to the developments of manufacturing equipment.At present,high-level CNC equipment is still relied on import,which is expensive and results in large consumptions of the cutters,as a result,the cost of manufacturing remains high.The market demands of large quantities and low costs can not be satisfied.By deeply studying on the theories of cutting methods of curved tooth bevel gears used on vehicle axles,processed by the high-level CNC equipment,the minuses on distributions of functions for which are founded.Based on the innovative design guided by the value engineering theories,the models of economical and functional CNC gears milling machines especially for Chinese market,as well as the corresponding calculations for the motional parameters are developed,based on which the economical and functional closed-loop manufacturing CNC tooth cutting production lines are constructed.The followings are the key results and innovations of this paper.(1)Based on the value engineering theories,the value improving methods of “persisting the necessary functions,eliminating the redundant functions and strengthening green manufacturing” are proposed from the prototype of the six-axis linkage CNC gears milling machine tool,aiming at solving the problem of “the high cost” for machining the curved tooth bevel gears by the imported machine tools.Guiding by the functional distribution and aiming at controlling of their life-time costs,the principles of innovative design for the economic and functional CNC gears milling machine tools are proposed and the closed-loop CNC production lines are arranged for machining spiral bevel gears.(2)The unified math models for machining both cycloid bevel gears and spiral bevel gears are setup,aiming at achieving the needs of highly effective machining of the curved tooth gears,used on vehicle driving axles,with lower costs,as well as,the needs of development for the CNC Format Generators with innovative structures and lower cost.The calculations of “equal cutting force feeding” for highly effective tooth cutting are performed.The simulation and cutting experiment verifies the validity of the math model and the applicability of the developed CNC machine tools.(3)Based on the demands of functions,by deeply studying the tooth surface forming mechanisms after B-axis degenerating of CNC milling machine,the unified math model for machining both cycloid bevel gears and spiral bevel gears is setup by introducing the rolling motion for modification.Applying equal transformations among coordinations,the calculation methods for motional parameters of B-axis degenerated CNC milling machines are setup.The corresponding cutting experiments verify the feasibility of the developed math models.(4)By abolishing the cradle and degenerating the linkage of B-axis,the math model of the “new style of cutting tilt method” is setup for machining spiral bevel gears and the formulas of calculating the motional parameters for all the servo axes of linkages are derived.Accordingly,the new CNC machine tool with innovative “cutting tilt” structure is developed,which can be used in machining spiral bevel gears with the “HFT” method.The simulated model of tooth cutting for this machine is setup by Vericut,performing the simulation of tooth cutting process.The cutting experiment and measurement of accuracy verifies that the machined gears can satisfy the requirements on surface accuracy of vehicle driving axles.(5)The mode of construction for the economical and functional CNC tooth cutting production lines is studied,according to the manufacturing requirements of curved tooth bevel gears used on vehicle axles.The methods of topological modification and equivalent tooth surface modification are proposed.The tooth surfaces for topological modification are constructed by properly determining the parameters of modification,and the machining parameters modification for the pinions can be achieved by equivalently compensating the surface deviations of the gears onto those of the pinions.By networking the milling machines and the measuring center,the mechanism of automatic feedback and modification of the tooth surface deviations for spiral bevel gears is setup.According to the common machining methods,HFT,HFM and SGM,for spiral bevel gears used on vehicle driving axles,the closed-loop production lines are founded.The tooth cutting experiments and industrial applications verify that the costs of purchase and cutter comsupsions are greatly reduced comparing with the imported,the technical advantages are prevailing comparing with the domestic.