| 摘要 |
A die-casting apparatus for the die-casting of metal into a specific part shape includes a pair of die-cast mold portions which are movable relative to one another and which define a die-mold cavity therebetween. The mold portions are initially separated so as to provide a venting gap and further include a communicating passageway between the die-mold cavity and the shot tube for the apparatus. The shot tube includes a metal inlet port and a cooperating plunger which is suitably designed and arranged to push the molten metal into the die-mold cavity. The shot tube is also fitted with gas inlets which are coupled to a supply of oxygen and a supply of combustion gas whereby an ignited flame may be injected into the shot tube. With the flame injected into the shot tube, the metal introduced and the inlet cover closed, the presence of the ignited flame increases the temperature not only of the air that is present within the shot tube and between the mold portions including the cavity, but the flame also contributes to a temperature elevation of the mold portions and the shot tube. The effect of this added temperature is to expand the volume of air which is trapped within the cavity thus reducing the actual amount of air. Under a somewhat constant pressure condition, the elevation in temperature results in a significant increase in the volume, thus reducing the amount of gas which is able to be trapped within the die-cast part.
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