Research On Machining Extrusion Die Of Spiral Bevel Gears With EDM

Spiral bevel gears are one of basic mechanical units to transmit motion between concurrent axes. Because the transmission has quite a few merits, such as the big overlap ratio, the high loading capacity, the high transmitting efficiency, the stability, the small noises, and so on, they are widely used in automotive vehicle, planes, machine tools and all kinds of machines. Because spiral bevel gears traditionally use cutting machining,this breaks the fibre of metal, let them lose their bending strength of tooth root,contact fatigue strength of tooth face and wearability, and abate earlier. Therefore researching new machining craft to improve the flaw of actual machining method is very important.Machining spiral bevel gears with extruding process is presented in this project, and machining extrusion die is the key of this technology. Because the internal curved surfaces of extrusion die is very irregular, and hard to machine. Using EDM can easily machine and assure precision. Based on this concept, for implementing machining extrusion die of spiral bevel gears with EDM, calculating tooth points of spiral bevel gears, the 3D-modeling of spiral bevel gears, design electrode and its feed path are researched in the dissertation.The precise 3-D modeling of spiral bevel gears directly influences the design precision of the electrode and electrode feeding path in EDM, is the prerequisite of extrusion die of spiral bevel gears with EDM. And the tooth profile of spiral bevel gears is very irregular, can't use explicit formula to express, so need to know some coordinate value of tooth points, and completing 3D-modeling by rebuilding the surface.The method of calculating tooth points is presented in this dissertation. First, the design and generating machining principle of spiral bevel gears is depicted, and the equation group of calculating tooth points of spiral bevel gears is built. This equation group can be found roots by using Newton iterative method. At last, the application of calculating tooth points software is implemented by three modules, and validated by an example of calculating tooth points of a pinion.After getting the coordinate of tooth points of spiral bevel gears, using application of universal CAD/CAM software to model and machine. This dissertation uses the free-form surface module of UG NX to model the outline and cone, and disposes their transition. Combining the characteristic of EDM, and considering the characteristic of extrusion die of spiral bevel gears, using shaped electrode machining to machine it. Therefore, the material,design,feed path of shaped electrode are researched.