| 摘要 |
PURPOSE:To reduce the deviation from a target pattern by controlling a proportional control valve with an analog value obtained by adding a correcting analog value to a steady analog value. CONSTITUTION:Compressed air from a compressed air source 1 is supplied to a molten metal holding furnace 7 through a mist separator 2, a primary reducing valve 3, a proportional control valve 4, a surge tank 5, and a filter 6, and the surface of a molten metal M is pressed to fill the molten metal M into a mold 9 by a stork 8. In this molten metal filling process, the proportional control valve 4 is controlled by a computer 10 to supply compressed air, which has the pressure controlled in accordance with the target pattern, to the holding furnace 7. This computer 10 calculates the steady analog value of the proportional control valve 4 and calculates the correcting analog value in accordance with the pressure deviation and adds these both values. This added command analog value is subjected to D/A conversion and is inputted to the proportional control valve 4. As the result, the surface of the molten metal is pressed with a pressure approximating the pressure of the target pattern.
|
