Die casting machine and casting method

A die casting machine for exhausting a cavity defined between a pair of dies to reduce the pressure in the cavity and for injecting and filling a molten metal into said reduced pressure cavity to form a cast product, comprising:

• a valve for opening and closing an exhaust path for exhausting the inside of said cavity;
• a value operation detecting means for detecting an opened state or closed state of said exhaust path by operation of said valve;
• an injection apparatus including an injection sleeve in communication with said valve, an injection plunger for injecting the molten metal supplied to said injection sleeve, and a drive means for driving said injection plunger;
• a plunger position detecting means for detecting a position of said injection plunger;
• and
• a control means including
• a cast condition holding means for holding a cast condition,
• a valve control means for controlling a drive of the valve,
• a valve closed position determining means for determining a closed position of the valve, and
• an injection controlling means for controlling a drive of the drive means in the injection apparatus, in accordance with the cast condition held in the cast condition holding means, to drive said injection plunger at a low injection speed defined by the cast condition after the molten metal is supplied to said injection sleeve, for switching to a high injection defined by the cast condition speed from the low speed when a speed switching position defined by the cast condition is reached, and for making the molten metal to be injected and filled into said reduced pressure cavity,
• said injection controlling means outputting control instructions to the valve control means for closing the valve so as to close said exhaust path when the position of said injection plunger detected by the plunger position detecting means reaches a valve closing position defined by the cast condition before reaching said speed switching position, and to the drive means in the injection apparatus for stopping the drive of said injection plunger when the valve closed position determining means does not detect completion of closure of said exhaust path when said injection plunger reaches said speed switching position.