Injection control method of die-casting machine and injection control unit of die-casting machine

An injection control method for a die-casting machine, wherein molten material is injected into a casting mold by an injection cylinder unit, comprising:

• setting target velocity data specifying an injection operation required for the injection cylinder unit in advance;
• performing a first shot of an injection operation, and recording command data provided to the injection cylinder unit and detecting velocity data indicating the operation performed by the injection cylinder unit during the first shot of the injection operation;
• determining a difference between the detected velocity data and the target velocity data;
• calculating a correction value based on the difference by operating the injection cylinder unit for a predetermined number of the injection shots by injection position feedback control;
• terminating the injection position feedback control after the predetermined number of injection shots;
• using the calculated correction value and generating command data for a second shot of the injection operation;
• and
• operating the injection cylinder unit by providing to it the command data for the second shot of the injection operation while shifting the control to open loop control of injection velocity by command data generated from the correction value and the previous command data, wherein
• a value of servo delay in the injection cylinder unit is set in advance,
• in calculating the correction value, the difference between the detected velocity data and the target velocity data is calculated in a state that the phase of the detected velocity data is advanced by the servo delay, and
• adjustment of the servo delay is made for each of low-velocity section, high-velocity section, and deceleration section of a shot of the injection operation.