US Patent 7846358 Method of controlling injection molding machine

When the number of rotations of a drive motor (3) driving a hydraulic pump (2) is variably controlled and thus each operation process in a molding cycle is controlled, as the hydraulic pump (2), a hydraulic pump (2) that can set at least a high fixed discharge flow rate (Qm) and a low fixed discharge flow rate (Qs) lower than the high flow rate is used, limit conditions for a threshold for the load condition of the drive motor (3) are preset and, during a molding operation, by setting a predetermined operation process at the high fixed discharge flow rate (Qm), the operation process is controlled and, when the load condition of the drive motor (3) is monitored and the load condition reaches the limit conditions, the flow rate is switched to the low fixed discharge flow rate (Qs) to control the predetermined operation process.