Study of Drawing and Heading Processes of Magnesium Alloy Screws

• Main Authors: Chia-Yu Chang, 張家毓
• Other Authors: Yeong-Maw Hwang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/39699458595713091761

碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 100 === Screws are produced by four manufacturing processes : extrusion, drawing, heading and thread-rolling. This paper will develop the related manufacturing technology of LZ91 magnesium alloy screws. At first, finite element simulation is adopted to analyze the effects of each process parameters on the formability. Then, each process experiments are conduted to manufacture an M6 magnesium alloy screw. Comparisous between analytical and experimental results verify the suitability and accuracy of the analytical models. In the extrusion process, by the finite element simulations the extrusion load is obtained. Then bar extrudsion experiments with high extrusion ratioto manufacture two bars of 6.5 and 7 mm in diameter using a 350 ton extrusion machine . In the drawing process, the effects of reduction and friction factor on the optimal semi-die angle are discussed, and the relationship is found. Then a rod of 7.0 mm in diameter is drawn into 6.5 mm experimentally. In the heading process, three stages in it`s process are designed. The arc shape and axial length of the die for the first stage are found out. Finally, heading experiments are conducted and sizes between the product and the simulation results are compared. In thread-rolling process, the effects of the screw plate gap on the formability are discussed numerically. Then, thread-rolling experiments are conducted to compare the sizes of the product and the simulation results. In addition, microstructure observation and hardness test are conducted to understand the effects of drawing process on the strength of the product.