| Summary: | 碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 102 === This study investigated the effects of forming temperature and speed with the combination of mold design on the LZ91 magnesium alloy screw heading and Rolling formability by the finite element analysis.. Then use the same conditions were simulated to do experiments. The accuracy of the experimental results with the simulation results are compared to confirm the analytical model, the results will be provided to the screw industry for reference and application.
In Screw Heading process, the simulation results were found by changing the guide shape of Shaft extrusion Die can effectively increase the material flow and reduce the effective stress and forging force. Changing the shape of punch can effectively decreases material defects occur, as the temperature increases, the forging force will decreases, forming speed no significant effect on the formability. The experimental results show that, althouth LZ91 can be formed at room temperature conditions, but ineffective. Forming temperature for better results are obtained 80℃ to 100℃, Screw Heading yield can reach more than 90%. When the temperature above 100℃, hexagonal needle and the billet began to appear adhesion. when the temperature more than 180℃, screws’ surface began to oxidize.
In Screw Rolling process . from the simulation and experimental results were found that. traditional screw thread rolling dies plates and screws have a relative sliding phenomenon. After changing the screw thread rolling dies plates length and increase the friction coefficient, which can effectively improve the relative sliding phenomenon. reduce Rolling speed can effectively reduce tooth crack occur. The temperature of screw thread rolling and screw heading is approximately the same . temperature set from 80℃ to 100℃ will obtain better screw shape.
|
|---|
