The die device for vacuum formation and in closed die forging vacuum forming the seal pressure control manner

摘要

PURPOSE:To accurately seal a parting face and thus maintain a high air tightness so as to permit the cavity of a metal die to be evacuated in a short time by providing a hollow O-ring on the parting face of one mold of a metal die in such a manner as to enclose a cavity. CONSTITUTION:A hollow O-ring 12 is provided on the parting face of a movable mold 3 in such a manner as to enclose a cavity 9. Molds are then closed and, at the moment the hollow O-ring 12 contacts a fixed mold 12, the evacuation through air escaping holes 10 and 11 is started. Since the elastic modulus of the hollow O-ring 12 is large, an O-ring larger than the standard ring can be used to make a clearance on the parting face larger. Therefore, a space between the fixed mold 2 and the movable mold 3 affords sufficient gap to provide a larger conductance and the inner pressure of the cavity 9 reaches instantaneously a vacuum forming pressure. After complete closing of the molds, resins are injected from the nozzle of a forming machine to be filled in the cavity 9 through a sprue 6, a runner 7 and a gate 8.