Centre Winder Torque Control for Density Correction
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Solution Overview
Problem
In the paper industry, post-processing machinery faces challenges in accurately controlling web tightness due to incorrect density data of paper rolls, leading to production losses and poor-quality rolls, as existing methods rely on manual corrections and are unreliable.
Innovation Solution
A method and apparatus that corrects the density value of the material being wound in real-time during acceleration, using a tightness controller to adjust torque calculations and ensure accurate moment of inertia calculation, thereby maintaining uniform web tightness and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If density data is obtained from paper roll data or manual entry, then the system can operate with available information, but the density value may be erroneous leading to web tightness variations and production losses
Solution Approach 1:
The system uses feedback from the tightness controller's torque calculation corrections to identify and correct erroneous density values. The feedback mechanism monitors whether torque corrections are needed and uses this information to adjust the density value, thereby improving reliability and preventing production losses.
Solution Approach 2:
The system performs self-correction of density values by automatically detecting errors through torque calculation feedback and adjusting the density parameter without external intervention. This self-service capability ensures continuous accurate operation and prevents production disruptions.
2Reliability
If empirical visual monitoring is used to correct density values, then operator experience can guide corrections, but the procedure is unreliable and requires great skill
Solution Approach 1:
The system replaces manual visual monitoring and empirical correction with an automated electronic control system. The tightness controller automatically detects density errors through torque calculation feedback and performs corrections without requiring operator skill or visual inspection, thereby improving reliability and simplifying operation.
Solution Approach 2:
The system performs self-correction of density values automatically through feedback from torque calculations, eliminating the need for operator intervention. This self-service mechanism ensures consistent reliable corrections without requiring skilled manual monitoring.
3Productivity
If incorrect density data is used for moment of inertia calculation, then the system can proceed with available data, but web tightness control accuracy deteriorates
Solution Approach 1:
The system continuously monitors torque calculation requirements and uses feedback from the tightness controller to detect when density data is incorrect. This feedback loop enables real-time correction of density values, maintaining both process continuity and tightness control accuracy throughout operation.
Solution Approach 2:
The system dynamically adjusts the density parameter based on feedback from torque calculations. When incorrect density data is detected through torque correction requirements, the system changes the density parameter to the correct value, thereby maintaining manufacturing precision without interrupting the winding process.
Data Source
Figure 1
AI summary
A method and arrangement in connection with a continuous material web, the material web running from an unwinder to a winder, at least one of the (un)winders being a centre winder, wherein the centre winder is controlled by an electric drive provided with a torque control. The method comprises giving an initial value for density of a material on the centre winder, calculating a moment of inertia for a roll of material on the centre winder, determining tightness of the material web by a mechanical sensor, producing, by a tightness controller, a correction term for torque calculation on the basis of a material web tightness reference, the determined material web tightness and the moment of inertia of the roll of material on (4) the centre winder, calculating a torque reference on the basis of the correction term produced by the tightness controller and the calculated moment of inertia of the roll of material (4) on the centre winder, and controlling the torque of the centre winder on the basis of the torque reference. The method comprises correcting the density value of the material on the centre winder on the basis of the correction term produced by the tightness controller.