As important light-weight structure material, aluminum alloys have been widely used in automotive and aerospace industries. In the last years, the manufacturing of parts with high strength and good dimensional accuracy has become the main objective in industrial applications. Within the available aluminum alloys, the 7xxx series has attract the interest of the industrial designers due to the high yield strength and ultimate tensile strength they present. However, the formability of these alloys in as-received industrial condition is very poor at room temperature and various studies are being carried out to develop efficient warm and hot forming processes to form them industrially using heated tools. In the present paper, the W-Temper forming is studied as an alternative to the warm and hot forming processes. Heat treatment temperatures and critical times are presented and an industrial B-Pillar is formed to validate the new process. In the last chapter, the final mechanical properties of the part are reported, before and after a virtual e-coat process where the W-Temper forming is compared with a hot stamping process.
The present paper is focused on the thixo lateral forging of a nearly 3 Kg commercial automotive spindle. A thixoforming cell has been implemented in the forming lab consisting on an induction unit, six-axes industrial robot for the handling tasks and a servo-mechanical forming press. A special tool has also been designed in order to use all the press capacity during the forming stage. First trials have been made using LTT45 steel. The usual material for this spindle fabrication is a CrMo alloyed steel (W-Nr 1.7225) employed in automotive components with high requirements on toughness. The selected thixoforming steel has been modified to have a wider solidification range and lower solidus temperature.
Semisolid forging process requires special movement of the ram, until now only
achievable with hydraulic presses. The upper die, placed on the press ram, must move fast during
forming of the component in order to reduce segregation phenomena, and, once the part is shaped,
the die must squeeze the material so that the contraction of the material is overcome and no
shrinkage defects are formed. Traditional mechanical presses are not able to reproduce this kind of
cycles, only possible with hydraulic presses. The introduction of servo motors in mechanical presses
makes possible the achievement of those requirements, and, therefore, the use of these presses for
the semisolid forging processes. The main characteristic of this type of machines is the elimination
of the flywheel and the clutch; in the solution proposed by the press builder Fagor, the AC servo
motor drives the ram of the press by using a transmission based on gears and a crank. This paper
presents some of the results achieved during the semisolid forging of A356 aluminium alloy using a
400 tons Fagor servo motor driven mechanical press installed at the University of Mondragon.
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