PURPOSE: To prevent damage of casting dies owing to blank shooting by a plunger by emitting a signal and stopping the operation of the plunger when the molten metal to be cast is not poured into a die casting machine.
CONSTITUTION: Molten Al in a ladle 5 is poured into a die casting machine through the pouring port 3 of an injection sleeve 1 and is injected by a plunger 3 into the dies, by which the molten Al is cast under pressure. The temp. of the sleeve 1 is measured by a thermometer 6 and is inputted to an arithmetic processing part 7 by a temp. sensor 4 attached to the sleeve 1. If a substantial amt. of the molten Al exists in the sleeve 1, the temp. of the sleeve 1 rises to a prescribed temp. The difference between said temp. and the temp. when the sleeve 1 is empty is calculated by the part 7. If the molten Al does not exist at all in the sleeve 1 or exists therein in a small amt., the above-mentioned temp. difference is small and a control device is actuated by the output from an outputting part 9 for the temp. difference, by which the operation of the plunger is stopped. The failure of the casting dies by blank shooting of the plunger 2 is thus prevented.
INOUE OSAMU
USUI MOTOO
YANAGI YASUJI
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