Combination control for injection molding

In an injection molding apparatus having a ram that is controlled to move within a cylinder containing molten plastic to force the plastic from the cylinder and into a mold, the ram controlled in accordance with one or more segments defined by setpoints and control equations, the control equations operating on the setpoints to define the movement of the ram, a method of controlling the ram during the injection cycle comprising the steps of:

• retrieving from memory a first and second control equation;
• controlling the movement of the ram for a predetermined time during a first portion of each segment in accordance with the first control equation;
• monitoring the movement of the ram to detect a predetermined movement of the ram and, if the predetermined movement is detected before the predetermined time, controlling the movement of the ram during a second portion of each segment in accordance with the second control equation;
• evaluating the movement of the ram near the end of each segment;
• and
• updating the first and second control equations for use in the corresponding segments of subsequent injection cycles.

A controller for use with an injection molding apparatus comprising:

• a first set of controller parameters that operate upon a stored setpoint, the first set of controller parameters defining the controller operation for an open-loop mode;
• a second set of controller parameters that operate upon a stored setpoint, the second set of controller parameters defining the controller operation for a closed-loop mode;
• a memory for storing the first and second sets of controller parameters;
• and
• a processor in communication with the memory, the processor operative to execute controller operations as defined by the first and second set of controller parameters and the stored setpoints, the processor being further configured to evaluate the controller performance during an injection cycle and update the first and second set of controller parameters based upon the performance evaluation, whereby the updated controller parameters are stored in the memory for use by the processor with the stored setpoints in subsequent injection cycles.

A controller for use with an injection molding apparatus having a ram that moves within a cylinder to force molten plastic contained within the cylinder into an injection mold that is disposed in fluid communication with the cylinder, the controller operative to control a flow control valve that is in fluid communication with the ram wherein movement of the ram is controlled by the flow control valve, the controller comprising:

• a first set of parameters that operate upon a stored setpoint, the first set of parameters defining a first control equation for controlling the state of the flow control valve in an open-loop mode;
• a second set of parameters that operate upon a stored setpoint, the second set of parameters defining a second control equation for controlling the state of the flow control valve in a closed-loop mode;
• a memory for storing the first and second sets of controller parameters;
• and
• processing means in communication with the memory, the processing means configured to retrieve the stored setpoints and the first and second sets of parameters and to control the state of the flow control valve in accordance with the first and second control equations, the processor further configured to evaluate the movement of the ram in comparison to the setpoints and update the first and second sets of controller parameters for use with the stored setpoints in subsequent injection cycles.