Injection molding method and control system for injection molding machines

An injection molding machine control system, said system comprising:

• a velocity control system, said velocity control system comprising a position detecting unit for detecting a position of an injection screw, a position setting unit for providing a set value of a position of the injection screw, and a first feedback circuit for outputting a first speed command value to an injection motor based upon a difference between a detected value from the position detecting unit and the set value from the position setting unit;
• a pressure control system, said pressure control system comprising a pressure detecting unit for detecting a resin filling pressure, and a pressure setting unit for providing a set value of a filling pressure and a dwelling pressure, and a second feedback circuit for outputting a second speed command value to the injection motor based upon a difference between a detected value from the pressure detecting unit and the set value from the pressure setting unit;
• a switching unit for switching between an output of the first feedback circuit and second feedback circuit to provide a selected speed command value to the injection motor;
• wherein the velocity control system is configured to perform a control action for returning the injection screw to a set position at a predetermined velocity when the injection screw has advanced to a predetermined position during a filling process, and wherein the switching unit switches to the second feedback circuit thereafter.

An injection molding machine control system, said system comprising:

• velocity control means for controlling an injection screw based on velocity control, said velocity control means comprising position detecting means for detecting a position of the injection screw, position setting means for providing a set value of a position of the injection screw, and first feedback means for outputting a first speed command value to an injection motor based upon a difference between a detected value from the position detecting unit and the set value from the position setting means;
• pressure control means for controlling the injection screw by pressure control, said pressure control means comprising pressure detecting means for detecting a resin filling pressure, and pressure setting means for providing a set value of a filling pressure and a dwelling pressure, and second feedback means for outputting a second speed command value to the injection motor based upon a difference between a detected value from the pressure detecting means and the set value from the pressure setting means;
• switching means for switching between an output of the first feedback means and second feedback means to provide a selected speed command value to the injection motor;
• wherein the velocity control means is configured to perform a control action for returning the injection screw to a set position at a predetermined velocity when the injection screw has advanced to a predetermined position during a filling process, and wherein the switching means switches to the second feedback means thereafter.