Directly Driven Roller Festoon Tension Control
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Solution Overview
Problem
The challenge in manufacturing disposable absorbent articles lies in managing tension fluctuations during the unwinding and splicing of flexible materials, particularly low basis weight non-woven webs, which can lead to web damage and process disruptions due to tension swings during speed changes and interruptions.
Innovation Solution
A web handling system that includes a tension sensing device, a festoon with movable guide rolls, and a controller to regulate tension by accelerating or decelerating guide rolls using drive devices, ensuring that the web speed matches across different sections to maintain consistent tension and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the unwind speed is decreased from process speed to a slower speed or stopped during splicing, then the splicing operation can be performed, but tension fluctuations occur due to spindle acceleration and deceleration, idle roll inertia, bearing friction, and air drag
Solution Approach 1:
A tension sensing device (load cell) provides real-time feedback on web tension during unwind and splicing operations. The controller receives this feedback and automatically adjusts the unwind speed to maintain tension within a predetermined range, preventing web damage during splicing operations.
Solution Approach 2:
The patent replaces traditional mechanical tension control methods with an automated control system that uses electronic sensing and control. The controller automatically regulates unwind speed based on tension feedback, eliminating the need for manual mechanical adjustments and providing more precise tension control during splicing.
2Productivity
If the second roll of material is accelerated to a rate greater than the process speed to re-supply the festoon, then the festoon can accumulate sufficient material, but tension variations occur that can cause web damage
Solution Approach 1:
The tension sensing device continuously monitors web tension during acceleration and material accumulation. The controller uses this feedback to regulate the acceleration rate of the second roll, ensuring tension remains within safe limits while still achieving the required accumulation rate for productivity.
Solution Approach 2:
The system dynamically adjusts the unwind speed during acceleration phases and steady-state operation. The controller modifies the speed profile of the second roll based on real-time tension conditions, allowing optimal acceleration rates that balance productivity with web integrity protection.
3Ease of manufacture
If web speed changes occur during splicing sequence, then the splicing operation can be completed, but tension swings can cause the web to become damaged
Solution Approach 1:
The load cell provides continuous tension feedback during the entire splicing sequence, allowing the controller to detect tension swings and automatically adjust unwind speed to maintain tension within predetermined limits, preventing web damage while completing the splicing operation.
Solution Approach 2:
The controller is programmed with predetermined tension limits and automatically takes corrective action before web damage can occur. By monitoring tension continuously and adjusting speed in advance, the system prevents tension swings from reaching damaging levels during splicing operations.
Data Source
AI summary
A web handling system and method for controlling tension in a web of material is disclosed. For instance, the web handling system is particularly well suited for maintaining web tension within predefined setpoints during temporary interruptions in the process, such as during splicing operations. The web handling system includes an accumulator or festoon that accumulates amounts of the material as the material is being fed downstream. At least one guide roll within the festoon is coupled to a drive device, such as a motor. The system also includes at least one tension sensing device. The drive device accelerates or decelerates the guide roll based upon information obtained from the tension sensing device. In one embodiment, the system further includes an electronic gearing configuration between a roll of material being unwound and the guide roll within the festoon for better synchronization and further minimizing tension swings. The electronic gearing can include a diameter calculator for the roll of material being unwound based on speed feedback of a driven guide roll.