| 摘要 |
PURPOSE:To control an injection motor so as not to overheat it by a method wherein the heat buildup of the injection motor is obtained on the basis of driving current flowing in the injection motor. CONSTITUTION:Since the heat buildup of a motor is proportional to the value obtained by integrating the square of driving current, a value proportional to the actual heat buildup is obtained by respectively multiplying the squares of respective current value, each of which is obtained by sampling the current intensity flowing in an injection motor in a predetermined period, by sampling periods during one injection molding cycle. Further, the value proportional to the heat buildup under the state that the injection motor is driven by the maximum current is obtained by multiplying the square of the maximum current flowable in the injection motor by the injection molding cycle period. When the ratio of the former value to the latter value exceeds the set predetermined value, the injection motor is judged whether it is in overheated state or not. When the motor is judged to be in overheated state, the injection molding cycle is elongated by providing a quiescent period in the injection molding cycle period so as to prevent the injection motor from being overheated. |
