| Precision forming technology of spiral bevel gear has many advantages, such as higher material utilization ratio, better fatigue performance and lower production cost. It's a new technology in gear manufacturing industry which is constantly studied and developed at home and abroad. The tooth profile of the spiral bevel gear is a helical. The flow route of the material from the teeth into the tooth cavity is a curve, which brings difficulties to shape and demound. Therefore, the precision forging process is still in development stage. It is important to research on the precision forging die design and analysis of spiral bevel gears considering the conditions of our gear industry improvement. The paper contains the following works:(1) precision forging die design and demoulding analysis. The demoulding process of the spiral bevel gears is an edge rotary edge vertical movement. It relies on the contact forces generated between the tooth surface in demoulding process. In order to make the gears demould smoothly, bearing-type mold structure is designed according to the characteristics of the spiral bevel gears structure. The dynamic analysis software ADAMS is used to analyze the demounding process. According to the force suffered on the tooth surface during the demoulding process, it can determine the feasible demoulding after precision forging of spiral bevel gear; the impact of structural parameters on the demoulding force are simulated. All the studies may provide the reference for the demoulding of the precision forging of spiral bevel gear.(2) Temperature field analysis for precision forging die. Surface temperature caused by heat exchange between the die and billet, and friction between the billet and mold surface during the forging process are important factors for the die's service life. Die temperature field in the process of precision forging is analyzed, the influences of process parameters on the mold temperature are discussed, and the relationship between the die temperature and forging speed, mold initial temperature, friction coefficient, billet temperature are established.(3) Von stress filed analysis for precise forging die. Rational design of tooth model structure can effectively reduce the forging load, improve the von stress of die, and increase the die's service life. Two kinds of tooth module structure are analyzed and calculated in forging time, and the Von stress distribution of the two kinds of structure are gained.(4) Wear analysis for precision forging die. Warm forging is working in the environment of high-temperature and high pressure, and the wear is caused by friction between die and billet parts. The failure of the die is caused by wear in over 70% cases during the process of warm forging, so it is necessary to analyze the wear of the die. Wear of the die is analyzed with the finite element method by using the Archard theory, the influences of parameters on the die wear are discussed, and the relationships between the die wear and forging speed, mold initial temperature, friction coefficient, and billet temperature are established.(5) Prediction of service life of the precision forging die. Die surface temperature has an important influence to the surface hardness and material properties in the forging process, so the temperature in the warm forging condition must be considered when calculating the amount of die wear, therefore, the Archard theory should be modified. The temperature, pressure and velocity field of nodes on cavity surfaces are gained by FEM simulation, and wearing depths are calculated by modified Archard theory to predict the service life of die...
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