A synchronous position control method at pressure control between multi-AC servomotors driven in injection molding machine

In coping with the trend toward the much higher powered electric-motor driven injection molding machine, multi-AC servomotors control system has become necessary in order to control the molding machine mechanism. Thus, it is inevitable to use a synchronous positioning control technique not to cause the excessive mechanical stress in the machine body. It is possible to realize the synchronous positioning control in the injection velocity control by using position feedback signals from motor pulse-generators. However in the injection pressure control it is much difficult to realize the synchronous positioning control because the pressure-detector signal have to be used in place of the position feedback signals. This paper clarifies the synchronous positioning control method during the injection pressure control by using both the pressure-detector signal and position feedback signals. The experimental results showed that the synchronous positioning control error was much less than 1 /spl mu/m in the pressure control.