Drift detection method for a control apparatus controlling an injection molding machine
AssigneeNissei Plastic Industrial Co., Ltd.
InventorsKazuo Usui, Susumu Morozumi
Life of this patent
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Abstract
In a drift detection method for detecting drift in a pressure detection value output from a pressure detector, pressure is detected by the pressure detector at a preset detection point in a pressure-uncontrolled region in an arbitrary molding cycle. The detected pressure is set as a reference pressure. Pressure is detected by the pressure detector at the same detection point in the pressure-uncontrolled region in a subsequent molding cycle. A deviation of the detected pressure from the reference pressure is obtained. When the deviation is greater than a preset value, it is determined that a drift is present, and processing for coping with the drift is performed.
Claims4
A drift detection method for detecting drift in a pressure detection value output from a pressure detector used in a control apparatus for controlling an injection molding machine, the method comprising the steps of:
- detecting, by use of the pressure detector, a first pressure at a preset detection point in a pressure-uncontrolled region in an arbitrary molding cycle;
- setting the detected pressure as a reference pressure;
- detecting, by use of the pressure detector, a second pressure at the preset detection point in the pressure-uncontrolled region in a subsequent molding cycle;
- obtaining a deviation of the detected pressure from the reference pressure;
- and
- performing correction processing for eliminating drift when the deviation is greater than a preset value, wherein the correction processing comprises the steps of:
- rotating a screw by one turn;
- obtaining a middle value between a minimum value and a maximum value of a pressure detection value output from the pressure detector during the one-turn rotation, the pressure detection value representing an error caused by ripples produced with rotation of the screw;
- rotating the screw further and stopping the screw when the pressure detection value output from the pressure detector becomes equal to the middle value;
- and
- correcting the pressure detection value after stoppage of the screw.
Dependencies are inferred from the claim text.