Abstract
In order to reveal abnormal shaped aluminum alloy law of needle piercing extrusion formation, setting the missile empennage as an example, this paper adopts the non-linear finite element to conduct the three-dimensional thermal simulation of abnormal shaped material law of needle piercing extrusion formation process and analyses systematically the influence of process law on temperature change, additional tensile stress and forming load. The results show that, in the range of low-speed extrusion, the billet’s highest peak temperature shows a decreasing trend, and with the extrusion speed increasing, the decrease of highest peak temperature decreases, while the axial extra tensile stress on the mouth of model increases accordingly; the axis part of the mold’s mouth is a high-temperature zone in the forming process, and with the axis center distance increasing, the temperature decreases gradually; and with the pressing reduction’s increase, the gradient of temperature decreasing trend slows down gradually. This provides a theoretical basis to technical design of abnormal shaped material needle piercing extrusion formation and the metal distortion flow control.

Key words
mandrel extrusion, aluminum alloys profile, coupled thermal-mechanical numerical simulation

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