Extruder Model for Cable Diameter Control
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Solution Overview
Problem
Existing methods for producing cables struggle to quickly adjust the outer diameter and wall thickness of cable strands to desired nominal values, especially when measurements are not taken directly behind the extruder, leading to slow regulation and potential over/under thickness issues.
Innovation Solution
A method involving an extruder model stored in a computer to calculate and adjust the diameter and wall thickness values by varying the screw speed and line speed, allowing for rapid adjustment to target values using a virtual measuring head to simulate immediate measurement feedback, even before reaching the actual measuring device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a measuring device is arranged between the extruder and the cooling section, then the regulation speed is improved, but the arrangement is undesirable for various reasons
Solution Approach 1:
The patent introduces a computer with an extruder model as an intermediary between the measuring device and the extruder control. The measuring device sends signals to the computer, which calculates the actual outer diameter using the extruder model and compares it with the target value, then sends control signals back to the extruder. This intermediary system enables fast regulation without requiring physical placement of measuring devices in difficult locations.
Solution Approach 2:
The patent replaces the need for physical measuring device placement with a computational model-based system. Instead of relying on mechanical/optical measurement systems that require specific physical locations, the system uses a computer model to calculate and predict the extrudate dimensions, substituting physical measurement with virtual measurement through mathematical modeling.
2Ease of manufacture
If a measuring device is arranged behind the cooling section, then the arrangement is feasible, but the regulation speed deteriorates
Solution Approach 1:
The system performs preliminary calculation of the actual outer diameter using the extruder model before the physical measurement is completed. The computer calculates the actual dimensions based on extruder parameters and compares them with target values in advance, enabling control actions to be prepared and executed faster, effectively reducing the regulation delay caused by the distance between the cooling section and measuring device.
3Manufacturing precision
If the wall thickness is adjusted by changing screw speed, then the wall thickness control is improved, but the extruder output fluctuates
Solution Approach 1:
The patent implements a feedback control system where the measuring device continuously monitors the outer diameter of the extrudate, sends measurements to the computer, which compares the actual value with the target value, and adjusts the screw speed accordingly. This closed-loop feedback enables precise wall thickness control while automatically compensating for output fluctuations to maintain stable production.
Data Source
AI summary
Method for the operation of a production plant to produce an extrudate, by extruding, in at least one extruder whose screw rotation rate is variable, at least one layer of the extrudate composed of plastic, where the velocity of the extrudate (linear velocity) is variable, and moreover by measuring the diameter and/or the wall thickness of the layer by using a measuring head at a distance from the extruder, characterized by the following steps: - in an extruder model in a computer, an algorithm is stored to calculate diameter values and/or wall thickness values of the layer, taking into account the rotation-rate-dependent output performance of the extruder, the internal diameter of the layer and the linear velocity, - the extruder model is generated from the volume output (extruder performance) via measurement of the wall thickness and/or of the diameter, the extruder rotation rate, the linear velocity and the internal diameter and/or the core diameter, - during production of the extrudate, the extruder model calculates, for an internal diameter, a linear velocity, a screw rotation rate of the extruder and rotation-rate-dependent data for the output performance of the extruder, the value predictable as generated by the extruder for diameter and/or wall thickness, - the calculated, predictable value for diameter and/or wall thickness is indicated and - the calculated and indicated value for diameter and/or wall thickness is brought to the specified value for diameter and/or wall thickness via change in the screw rotation rate of the extruder and/or the linear velocity.