| Spiral bevel gears are widely used in machine driven system such as automobiles, motorcycles and so on, because of their well driving performance. At present,Spiral bevel gears are mainly made with forged blank by Gleason Gear Cutter. Cold extruding technology has the advantages of higher efficiency, less raw materials, lower cost, higher strength and better surface quality and so on, especially in the mass production. If cold extruding technology is applied to the (near) net shape process of spiral bevel gear's tooth profile,it will illustrate a good prospect of application and extension. However, the shape of arc tooth is complex, which influences metal flowing and cause forming force increase quickly in cold extruding, so it is difficult to cold forming. In reality, the technical problem such as poor forming quality and low die life, impacts the application of the cold extruded technology at spiral bevel gears.In this papers , the cold extruding process of spiral bevel gear was simulated, with the help of the rigid-plastic finite-element software DEFORM-3D. The metal flowing situation and stress-strain distributions of parts during the forming process were obtained. The influences of the diameter of billet on the gear filling property were analyzed. And the forming force are compared with three cold upsetting extrusion process which included closed extrusion,extrusion with divided-flow hole and extrusion with lower punch. Through comparing the forming force with various diameter , the divided-flow hole were optimized. In addition, the forming force of extrusion with divided-flow is smaller than closed extrusion in heat-forge—cold-finish process.Finally, based on the existing equipment, experimental schemes were worked out. A three-layers combined cavity die and special cold extruding die guiding with orifice were developed. The process test shows that experiment result is in accordance with the theoretical analysis. |
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