Injection control apparatus for an injection-molding machine

An injection control apparatus for an injection-molding machine for performing injection control using a servomotor, said apparatus comprising:

• a serve circuit including an error register;
• a numeric control unit outputting pulse trains to perform injection control and hold pressure control including a move command signal which is delivered to the error register, wherein a pulse distributor corresponding to hold pressure control is started upon completion of a pulse distribution corresponding to injection control;
• means for stopping operation of the injection molding machine when an excessive move command is accumulated in the error register;
• pressure detection means for detecting injection pressure and outputting a pressure signal;
• injection high-timer means having an injection high-timer, for counting a predetermined time after an injection cycle starts and outputting a time-up signal upon elapse of said predetermined time;
• comparison means for comparing said pressure signal detected by said pressure detection means with a stored preset pressure signal and outputting an output signal when said detected pressure signal is higher than said preset pressure signal;
• hold pressure control means for starting hold pressure control in response to said time-up signal from said injection high-timer or said output signal from said comparison means;
• and
• means connected to the error register when a pulse distribution to a hold end position is not completed at the time said hold pressure control is completed, so thereby completing said pulse distribution.