| 摘要 |
PURPOSE:To obtain high quality castings free from shrinkage cavities by controlling local pressurizing in accordance with the optimum timings calculated automatically with the temps. of molds and molten metal as parameters. CONSTITUTION:When injection is started with a switch 9, molten metal 5 is charged into cavities 3; at the same time, a plunger cylinder 7 is operated with an elecyromagnetic selector valve 7 to pressurize the molten metal in the cavities 3 with a plunger 7a. In a pressurizing timing controller 10, the quick rise in the oil pressure of said cylinder 8 is received with the signal from a pressure switch 11, and with the point of the time when injection is completed as a reference point, the optimum timing time for pressurizing is calculated from the temps. of the molten metal 5 and molds 1, 2 detected with thermocouples 15, 12a, 12b, 13a, 13b. After the lapse of the timing time from the reference time, cylinders 16a, 16b are operated with electromagnetic selector valves 17a, 17b by the signals from terminals 10h, 10i, whereby plungers 16a', 16b' are forced downward and the cavities 3a, 3b are locally pressurized. |
