Research On The Novel Gear Cutting Method And Gear Cutting Machine Of Spiral Bevel Gear

Spiral bevel gear, an important part that transmits motion and power betweenintersecting axes or crossed axes, is widely used in automobile industry, aircraft industry,machine tool industry and many other industries. The main advantages of spiral bevel gearmeshing are high contact ratio and load capacity, smooth transmission and low noise. Inorder to obtain easy manufacture method, approximate tooth profile is selected instead ofspherical involute in tradition, and thereby the instantaneous transmission ratio cannot beconstant and the meshing is point contact at any instant. Thus, gear tooth surface has to bemodified as well as the gear cutting machine. A novel gear cutting method is proposed in thisthesis, the spherical involute generating line method. It researches the gear design andmanufacture from the tooth forming principle, and spiral bevel gear with spherical involutetooth profile can be obtained. There is no principle error on the tooth surface so that theaccuracy of the tooth surface can be improved. The tooth surfaces are conjugated to eachother so that the gears can be exchanged. The generating line is a simple geometry line sothat the cutting tool can be simple. The motions of generating line method are simple so thatthe gear cutting machine can be simple and thereby the cost on equipment will be low. Thethesis’ primary coverage is as follows:(1) The development and present research situation of spiral bevel gear aresystematically illustrated. The traditional spiral bevel gear cutting methods are summarized.The cutting principle and method of Gleason spiral bevel gear is illustrated. Then the mainresearch contents of this thesis are illustrated.(2) The theory of spherical involute generating line method is demonstrated, theforming of the spherical involute and its polar coordinates are illustrated. The formingprinciples of conical helical involute surface and conical arc involute surface aredemonstrated as well as the selection and forming principle of the generating line. Accordingto the generating line method, the manufacture method of skew bevel gear with sphericalinvolute tooth profile is researched, the motion of gear cutting machine is determined, andthe motion functions are deduced. (3) The gear cutting machine of spiral bevel gear with spherical involute tooth profile isdesigned. According to the generating line method and the motions of manufacturing thespiral bevel gear with spherical involute tooth profile, NC milling machine is selected as themain part of the gear cutting machine. The spindle is modified so that its angle can bechanged. Two NC rotary worktables are added on the milling machine worktable.3D modelof the gear cutting machine is built using CATIA. The model is imported to ADAMS and thecutting motion is simulated. The interference situation is checked during the simulation andthe dimensions of the gear cutting machine are optimized. The spindle angle changingmechanism and the part connecting two rotary worktables are analyzed using ANSYSWorkbench, ensuring they have enough strength and stiffness.(4) A pair of skew bevel gear is designed. The manufacture parameters are calculatedaccording to the generating line method and the motion functions, and the NC code isprogrammed. The cutting experiment is carried out on the gear cutting machine. Nylon isused in the experiment. The skew bevel gear with spherical involute tooth profile is obtained.The gear cutting experiment shows that the generating line method can manufacturespiral bevel gear with spherical involute tooth profile, and the gears can be meshing correctly.The motions of the gear cutting machine are simple as well as the cutting tool. The gearcutting machine is working stably and safely, and its performance is good.