| 摘要 |
PURPOSE:To decrease considerably formation of castings having cavities occurring in intrusion of gas in the stage of low-speed and high-speed injection, etc. of a molten metal when the die temp. is low and high by making use of a valve which is actuated by electromagnetic selector valves to release the gas in the casting cavity of a die casting machine. CONSTITUTION:An electromagnetic selector valve 34 is turned on to close a valve 7 communicating a casting cavity 4 with a vent groove 6 and a molten Al alloy or the like is first injected at a low speed into the cavity 4. Such operation is repeated several times to heat the stationary die 1 and movable die 2 forming the cavity 4. The electromagnetic selector valves 33, 34 are then held open to hold the valve 7 open and after a spool 9 is lowered, both valves 33, 34 are turned off to clamp both dies 1, 2, thereby forming the passage communicating to the outside of the spool 9 through the cavity 7, a vent way 5, the vent groove 6, a passage 8 and a valve chamber 11. If the molten metal is injected at a high speed in such a state, the gas in the cavity 4 is discharged in the above-mentioned passage and the formation of castings having cavities owing to intrusion of the gas is considerably decreased. |
