Injection method for melted metals

A metering and injection method for melted metals, comprising the steps of:

• providing an inclined in-line injection apparatus comprising:
• an inclined heating cylinder having a fore end portion and a rear end portion, the rear end portion having a first internal diameter and the fore end portion communicating with a nozzle member and having a second internal diameter, smaller than the first internal diameter, so that the fore end portion serves as a metering chamber having a required length;
• and
• an injection screw installed within the heating cylinder so that it is movable and rotatable, the injection screw comprising:
• a tip end, formed as a plunger having a diameter approximately the same as the second diameter and insertable into the metering chamber while keeping a clearance for sliding;
• a mid portion wherein a reservoir for the melted metal is formed between a first portion and an inner wall of the heating cylinder, the first portion being free of screw flights and having an external diameter smaller than the second internal diameter;
• and
• a feeding portion containing a screw flight having an external diameter approximately equal to the first internal diameter around a second portion for receiving and melting metal materials, the mid portion positioned between the tip end and the feeding portion;
• inserting retractably the plunger into the metering chamber;
• accumulating the metal materials, melted in the feeding portion by an external heater of the heating cylinder, in the reservoir utilizing gravity from a slope of the inclined heating cylinder;
• pulling a metered amount of the melted metal materials into the metering chamber from the reservoir by a negative pressure on the metering chamber side generated by a forced backward movement of the injection plunger;
• and
• injecting the metered amount of the melted metal material by moving the injection plunger forward toward the nozzle member.