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US 5,665,399 AGranted
Interface units for extrusion blow moulding control systems
OwnerGeorge Robin Enderbyinventor
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OwnerGeorge Robin Enderbyinventor
Estimating the term…
An extrusion blow mounding control system for controlling parison wall thickness in an extrusion blow moulding machine includes a wall thickness controller for controlling the width of an extrusion die gap defining parison wall thickness within the machine, an interface unit for supplying an input signal to the wall thickness controller dependent on an actual position signal from a position transducer indicative of the actual position of a movable die member delimiting the die gap, and an output for supplying a desired position signal from the wall thickness controller to an electrohydraulic servo valve for controlling the position of the movable die member to provide a desired width of the die gap. The interface unit includes signal processing circuitry for receiving the actual position signal from the position transducer and a feedback signal from an automatic weighing system indicative of weight variation of product outputted by the machine and for producing the input signal for the wall thickness controller in dependence on the actual position signal and the feedback signal. Such a closed loop control system can be used to control the weight of the final product within a narrow weight range, and this results in improved product consistency and quality, as well as enabling the total quantity of moulding material used in moulding of the product to be decreased.
An interface unit for an extrusion blow moulding control system for controlling parison wall thickness in an extrusion blow moulding machine, the interface unit being adapted to receive a position feedback signal dependent on the actual width of an extrusion die gap defining parison wall thickness within the machine, as determined by transducer means from the position of a movable member delimiting the die gap, and to supply an output signal to a wall thickness controller for supplying a desired position signal to displacement means for controlling the position of the movable member to provide a desired width of the die gap in dependence on a required parison wall thickness profile set within the wall thickness controller, wherein the interface unit comprises signal processing means for receiving the position feedback signal from the transducer means and a weight feedback signal from weighing means indicative of weight variation of products outputted by the machine, and for applying a correction to the position feedback signal in dependence on the weight feedback signal to compensate for underweight or overweight products outputted by the machine so as to produce said output signal for supplying to the wall thickness controller.
An extrusion blow moulding control system for controlling parison wall thickness in an extrusion blow moulding machine, the control system comprising a wall thickness controller for controlling the width of an extrusion die gap defining parison wall thickness within the machine, input means for supplying an input signal to the wall thickness controller dependent on an actual position signal from transducer means indicative of the actual position of a movable member delimiting the die gap, and output means for supplying a desired position signal from the wall thickness controller to displacement means for controlling the position of the movable member to provide a desired width of the die gap, wherein the input means comprises signal processing means for receiving the actual position signal from the transducer means and a feedback signal from weighing means indicative of weight variation of product outputted by the machine and for producing the input signal for the wall thickness controller in dependence on the actual position signal and the feedback signal.
Dependencies are inferred from the claim text.