| Face gear transmission is a kind of gear transmission mechanism composed of cylindrical gears and bevel gears.The traditional manufacturing method of face gear is based on the accurate simulation of face gear meshing with cylindrical gear.In order to solve the problem of complexity and universality of the tool structure,this paper studies the method of machining face gear with straight edge tool,and explores the influence of tooth surface modification parameters on the meshing performance of approximate face gear tooth surface.The main contents and corresponding results of this paper are as follows:(1)The tooth surface equation of approximate face gear was derived by designing the structure of straight edge tool.The influence of preset tooth surface contact trajectory on the tooth surface deviation of approximate face gear was explored.The tooth surface diagonal was selected as the best tooth surface contact trajectory by combining various factors.The influence of the outer radius of the straight edge tool and the arc radius of the top edge on the tooth root overcut of the approximate face gear was explored.In addition,the influence of the torque angle of the straight edge tool on the accuracy of the tooth surface of the approximate face gear was studied.The five-axis CNC machine tool structure was selected and the corresponding coordinate transformation system was established.The comprehensive motion rule of the approximate face gear machined by the straight edge tool was deduced.The machining experiment of the approximate face gear was carried out to verify the correctness of the straight edge tool machining face gear.(2)Based on the approximate tooth surface of the face gear,the tooth surface of the pinion conjugate with the approximate face gear was derived.The tooth surface of the pinion was actively modified by presetting the tooth surface contact path,the gear transmission error,and the contact ellipse’s long axis.The NURBS surface interpolation fitting method was used to reconstruct the fitting tooth surface of the modified gear.The tooth surface meshing performance of modified pinion and approximate face gear was analyzed.The results show that the tooth surface geometric contact path,contact ellipse long axis and geometric transmission error consistent with preset parameters can be obtained by active modification of conjugate pinion tooth surface,and the influence of gear installation error on tooth surface meshing performance can also be effectively eliminated.(3)A machining method based on four-axis CNC machine tool and multi-line envelope grinding face gear with straight-edge cutter was proposed.The straight edge tool with a circular arc on the top edge was designed to profile the tooth profile of shaper cutter,and the equation of the theoretical tooth surface of the face gear was derived.The contact line between two tooth surfaces was used as the tool path of straight edge cutter,and the influence of cutting edge arc radius and torque angle on the tooth surface enveloping residual was investigated by numerical simulation.the CNC motion rule of straight edge tool grinding face gear was deduced,and the simulation processing was carried out in VERICUT.The simulation model was compared with the theoretical tooth surface,and the maximum deviation of tooth surface was 4.7 μm,which verifies the correctness of the proposed machining method. |
