Servomechanical Press: A New Press Concept for Semisolid Forging
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.
G. Hirt, A. Rassili, A. Bührig-Polaczek
Z. Azpilgain et al., "Servomechanical Press: A New Press Concept for Semisolid Forging", Solid State Phenomena, Vols. 141-143, pp. 261-266, 2008