Patent ID: 7088069

Claim:
A load monitoring method for monitoring load of a drive section provided in a motor-driven injection molding machine and using a drive motor, the method comprising the steps of: obtaining an average load level of the drive section for each molding cycle; calculating a cycle extending time or a cycle shortening time which is necessary for decreasing or increasing the average load level to a previously set reference load level; and displaying the cycle extending time or the cycle shortening time, wherein the average load level for each molding cycle is obtained from the square root of {(x 1 2 ·t 1 +x 2 2 ·t 2 +x 3 2 ·t 3 . . . x n 2 ·t n )/tm}=(Pm/tm), where x represents a ratio of load current to a maximum load current at which continuous operation is possible, t represents time and Pm represents load level, load factor, of a single molding cycle and tm represents a period of time of a single molding cycle.