Incremental Web Stretching via Segmented Activation Members
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Solution Overview
Problem
Existing methods for stretching nonwoven fabrics and films often result in damage due to high strain rates, which are detrimental to materials like polypropylenes, polyethylenes, and polyesters, especially during commercial production at high line speeds.
Innovation Solution
The use of activation members with teeth and grooves that complement each other, allowing for incremental stretching at a low strain rate through a deformation zone with a controlled increase in depth of engagement, minimizing web damage while maintaining high processing speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high line speeds are used for commercial production, then productivity is improved, but the strain rate increases causing damage to the web
Solution Approach 1:
The activation path is divided into multiple discrete teeth and grooves that engage sequentially along the deformation zone. This segmentation allows the total strain to be distributed across multiple smaller deformation steps, reducing the strain rate at any single point while maintaining high line speeds for improved productivity.
2Device complexity
If activation rolls with short activation path length are used, then device complexity is reduced, but the strain rate increases causing web damage
Solution Approach 1:
The activation members are designed with teeth and grooves that extend in the cross-machine direction, creating a deformation zone with extended path length without increasing the machine-direction footprint. This dimensional approach allows longer activation paths while maintaining compact device configuration.
3Strength
If depth of engagement is increased to improve stretching effectiveness, then strength is improved, but web damage increases due to high strain rate
Solution Approach 1:
The total depth of engagement is segmented across multiple teeth and grooves along the deformation zone. Each tooth-groove interface provides a small incremental deformation, distributing the total strain across many small steps. This achieves effective stretching for improved strength while maintaining low strain rates to prevent web damage.
4Object-affected harmful factors
If incremental stretching at low strain rate is implemented, then web damage is reduced, but the deformation zone path length increases requiring more space
Solution Approach 1:
The deformation zone is extended in the cross-machine direction using teeth and grooves arranged perpendicular to the machine direction. This allows the activation path length to increase without proportionally increasing the machine-direction space requirement, enabling low strain rate processing in compact footprints.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively stretches webs without causing significant damage, even at higher speeds, by distributing strain evenly and reducing material destruction, thus preserving the integrity and properties of the materials.
Implementation Method 1
incremental stretching of the web at a low strain rate through a deformation zone
Data Source
AI summary
A method and apparatus is provided which uses activation members for incrementally stretching a web at a low strain rate. The activation members include an activation belt and a single activation member wherein the activation belt and single activation member comprise a plurality of teeth and grooves that complement and engage one another at a depth of engagement in a deformation zone. The depth of engagement can be controlled to increase linearly over at least a portion of the deformation zone such that a web interposed between the activation belt and the single activation member in the deformation zone is incrementally stretched at a low rate of strain.