||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.