Servo control for molding machine

A method for servo control of an injection molding machine mechanism control valve, the machine having transducers for producing measured parameter signals representing measured values of selected machine conditions, a desired operation of the controlled mechanism being defined by set point signals representing set point values of machine operation parameters, the method comprising the steps of:

• a. periodically sampling measured parameter signals representing mechanism conditions at a predetermined loop closure interval to produce analogue input signals;
• b. producing during the loop closure interval a first command value in response to a first selected analogue input signal, a first set point signal, and a predetermined algorithm relating the first set point value and a first measured parameter value affected by operation of the controlled mechanism;
• c. producing during the loop closure interval a second command value in response to a second selected analogue input signal, a second set point signal and a second predetermined algorithm relating the second set point value and a second measured parameter value affected by operation of the controlled mechanism;
• d. comparing the first command value to the second command value to determine the larger value;
• e. selecting a command value in response to the comparison;
• and,
• f. producing a valve control signal in response to the selected command value.

A method for servo control of injection molding machine devices including machine mechanisms and heaters, the machine having transducers for producing measured parameter signals representing measured temperatures and values of selected machine conditions, the devices being controlled in response to control signals produced in response to set point signals representing set point values defining desired operation of the devices, the method comprising the steps of:

• a. periodically producing first interrupt signals defining a first predetermined loop closure interval;
• b. periodically producing second interrupt signals defining a second predetermined loop closure interval;
• c. sampling measured parameter signals representing mechanism conditions at the first predetermined loop closure interval;
• d. sampling measured condition signals representing temperature at the second loop closure interval;
• e. executing analogue loop algorithms relating first selected parameter values, first selected set point values, the first predetermined loop closure interval and the mechanism condition values to produce mechanism control signals at the first loop closure interval;
• and,
• f. executing control temperature loop algorithms relating second selected parameter values, second selected set point values, the second predetermined loop closure interval and the measured temperatures to produce heater control signals at the second loop closure interval.

A method for servo control of an injection molding machine mechanism control valve, the machine having transducers for producing measured parameter signals representing measured values of selected machine conditions, a desired operation of the controlled mechanism being defined by set point signals representing set point values of machine operation parameters, the method comprising the steps of:

• a. periodically sampling measured parameter signals representing mechanism conditions at a predetermined loop closure interval to produce analogue input signals;
• b. producing, at the predetermined loop closure interval, a command value in response to a selected analogue input signal, a set point signal, and a predetermined algorithm relating the set point value and a measured parameter value affected by operation of the controlled mechanism;
• c. producing, at the predetermined loop closure interval, a valve current value in response to executing a valve position loop algorithm relating the command value, the predetermined loop interval and a measured valve position;
• and,
• d. producing, at the predetermined loop closure interval, a valve control signal in response to executing a current loop algorithm relating the valve current command value, the predetermined loop closure interval and a measured valve current.