Finite Element Simulation and Experiment of Orbital Hot Forging for Bevel Gear
| Autor: | Kun-Long Cheng, 鄭焜隆 |
|---|---|
| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 The current study aims to explore the orbital hot forging process of bevel gears. Firstly, the material properties of AISI-1045 steel were analyzed, and the experiments and simulation of the forming models of bevel gear were also compared. Then, the finite element simulation was applied to analyze the orbital hot forging process for bevel gear, and the differences in forming load, deformation type, effective stress, effective strain, and microstructure grain between orbital forging and traditional forging were compared. The effects of the process parameters, such as pre-form, inclination angle, rotational speed, temperatures, feed rate, and the interface friction factor, on the plastic forming and microstructure of bevel gear were further explored. In addition, to predict the change of thermo-mechanical behavior of bevel gear forgings, the phase transformation on the bevel gear forgings in different cooling manners were also investigated to explore the microstructure evolution of the actual behavior. The analysis results show that the deformation modes in various stages of bevel gear between finite element simulation and experiments have extensive consistency. Through analysis and comparison, the forming load of the orbital forging is about 1/3 to 1/5 of that of the traditional forging. The effective stress distribution in bevel gear generated by orbital forging is less than by traditional forging. The effective strain distribution by orbital forging is more regular and also larger than by the traditional forging. The grain refinement by orbital forging process is more uniform than by the traditional forging, in which the grain refinement is almost located at the tooth section. In addition, the flow of materials could be improved, and the fold defects of materials could also be avoided when reasonably changing the geometric shapes of billet or appropriately selecting the inclination angle, rotational speed, and feed rate. Through analysis of process parameters, the forming load could be reduced by using larger inclination angle, higher rotational speed, slower feed rate, and higher forming temperature. As for the effective stress, the spindle root section suffers the maximum stress, and the stress increases with smaller inclination angle, slower rotational speed, slower feed rate, and higher forming temperature. In addition, the effective strain generated by the process parameters has considerable consistency, mainly because the section of tooth has suffered a greater impact with different parameters. Generally, the effective strain increases with higher rotational speed, slower feed rate, and lower forming temperature. Different inclination angles will generate different effects on the effective strain in the tooth section. The microstructure grain size has refined in various process conditions. Study results show that the refinement effect of grain size increases as the rotational speed and interface friction factor increase. With different inclination angle, feed rate, and forming temperature, the influences on micro grain size are different. The phase transformations of thermal-mechanical cooling are different in various cooling ways. By water-cooling and oil-cooling after forging, the austenitic structure can all be transformed to high hardness martensite structure at the tooth section of bevel gear, but some transformed to the pearlite structure at spindle section. However, the original austenitic structure has transformed to pearlite structure in air-cooling. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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