In modern day casting machines, it is essential that the molten metal be delivered in amounts and under pressures such that the die or mold will be filled but not over filled. However, in most casting operations the plants still use ladles as means to transport the molten metal to the ram chamber of existing shot mechanisms of present day die casting or stripcasting machines and, thus, production is in the nature of a batch or semi-batch operation to the die casting machine. In addition when the metal is magnesium such systems have difficulty excluding ambient atmosphere from coming into contact with the metal which creates a safety hazard as well as contaminating the metal with the oxides of the molten metal.
It would therefore be advantageous to have a system where the metal was delivered from a remote location in pipes to the shot mechanism and have a shot mechanism which can through pressure-time relationship deliver definite quantities of metal to the die as well as exclude the metal from contact with the ambient atmosphere and include an inert gas or mixture or air to which CO.sub.2 and between 0.1 and 1% sulfur hexafluoride sweep to the ram chamber and the mold to further prevent the metal from coming into contact with the ambient atmosphere or provide a protective film at the metal gas interface to prevent or reduce oxidation of the metal which flows into the mold when the mold is opened to eject the molded article.
USPTO Backgrounds
USPTO Backgrounds