Numerical Simulation Of Warm Precision Plastic Forming Of Bevel Gear

This paper deals with numerical simulation of warm precision plastic forming of bevel gear. Adopting warm precision plastic forming technology of helical gear, comparing with tradition forming method, can decrease cost, enhance work efficiency and gear intensity.The bevel gear is built parametrically with 3D CAD software UG. Adopting 3D finite element simulation software DEF0RM-3D, the simulation is employed to examine the closed-die forging process in bevel gear. Selecting temperature, friction coefficient, modulus, helix angle, taper angle parameters, the closed-die forging process in bevel gear is simulated frequently. The effective stress distribution, the effective strain distribution and the load-stroke curve of the whole process are got. Based on the simulation result, analyzing hereinbefore parameters effect on the closed-die forging process in bevel gear, the rule of these parameters effect on the closed-die forging process in bevel gear is obtained. It can help the research of the closed-die forging process in bevel gear.The helical gear of automobile gear-box is formed by closed-die forging for two billets, one is convexity, the other one is column. Compared with the convexity billet, the column billet is processed easily and saves material. Analyzing their numerical simulation results, the forming of column billet is the same as the convexity billet. But the effective strain of column billet is higher than the convexity billet, so the load of column billet is higher than the convexity billet as well. During the forming process, at the early stage of metal flowing into the gear cavity, the effective stress and the effective strain are very high at the base of gear; while at the late stage, the effective stress and the effective strain are very high at the top of gear.As to precision plastic forming of spiral bevel gear, two precision shape forming methods are adopted, one is closed-die forging, the other one is rotary forging. In the bevel gear rotary forging process, in contact area, metal which is at the top of the billet flows into gear cavity firstly. Then metal flows into gear cavity along bevel surface from top to bottom. In the end, metal which is at the bottom of the billet flows into gear cavity. The load of rotary forging in spiral bevel gear is 550KN which is 1/9 of the load of closed-die forging at the same condition. Meanwhile metal flows equably, and doesn't collide at all. Rotary forging in spiral bevel gear avoids pucker bug.As to the problem of bevel gear escaping from bottom die, the bottom die is designed to be centripetal axletree configuration. when the bevel gear is pushed out, the bottom die rotates synchronously along axis, the work piece is departed from the bottom die.