Die casting method and die casting machine

Abstract

The present invention provides a die-casting method comprising the steps of evacuating a cavity defined by dies of a die-casting machine to provide therein a vacuum of 100 millibar or less during a first period, injecting a reactive gas from a sleeve of the die-casting machine into the cavity during a second period which has a partial overlap period with the first period and follows the overlap period, so as to increase the inner pressure of the cavity to atmospheric pressure or more, pouring a molten aluminum alloy M into the sleeve while keeping the injection of the reactive gas, and subsequently moving a plunger in the sleeve forward to forcibly inject the molten aluminum alloy from the sleeve into the cavity while re-evacuating the cavity The evacuation, reactive-gas injection and re-evacuation operations can be performed with respective overlap periods therebetween. During the operation of supplying the molten aluminum alloy, air and water are effectively discharged to outside, and the reactive gas in an unreacted state is discharged to outside without being incorporated into the molten aluminum alloy. Thus, the present invention provides a die-cast product having a significantly reduced volume of incorporated gases and allows the die-cast product to be applied to functional members.