| 摘要 |
[Problem] With regard to screw back pressure control during the plasticization step in an electric injection molding machine, there has been a demand for a method for detecting screw back pressure with high precision and extremely small time lag without using an expensive pressure detection sensor that requires complicated installation work, a complex mechanical structure, and manual operations such as performing measures against noise or adjusting the zero point. [Solution] A high gain observer that incorporates a discrete arithmetic expression derived by using an output equation and a state equation expressing a numerical model of the plasticization mechanism of an electric injection molding machine is employed. The high gain observer receives, as the input signal, a screw retreat speed signal in addition to an injection motor current command or the actual motor current and a screw rotation signal, and outputs an estimated screw back pressure value which is one of the state variables. The high gain observer outputs an estimated screw back pressure value with high precision and extremely small time lag without the need of a pressure detection sensor. Therefore, the estimated screw back pressure value outputted from the high gain observer can be used as a feedback signal for screw back pressure control during the plasticization step.
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