To control pressure with high speed loop gain by suppressing oscillation in pressure control provided with a speed control loop in a pressure control loop.
A pressure filter 10 constituted of a band elimination filter which attenuates a resonance frequency band component of a control object (injection mechanism) in injection pressure control is disposed in a pressure feedback passage from a pressure sensor 7. A pressure compensation device 1 asks for a speed command based on the deviation between a command pressure and a pressure feedback signal of which the resonance frequency band component is attenuated by the pressure filter 10. An electric current command is asked by a speed compensator 2 from the speed deviation between the speed command and the real speed of a servomotor 5 which drives an injection screw fed back from a speed detector 6. Electric current loop processing is executed by the electric current command, and the servomotor 5 is driven via an amplifier 4. Since the resonant frequency component of the control object is attenuated, oscillation does not occur even if a speed loop gain is raised, and stable pressure control with good response can be executed.
KOMIYA SHINGO
HASE MOTOHIRO
Hideo Sugiyama
Koichi Yuda
Uozumi Takahiro