Incremental Web Stretching via Interlocking Teeth and Grooves
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Solution Overview
Problem
Existing methods for stretching nonwoven fabrics and films often result in material damage due to high strain rates, which are detrimental for materials like polypropylenes, polyethylenes, and polyesters used in commercial production, as they cannot withstand the high rates required for maintaining desirable properties such as strength, softness, and elasticity.
Innovation Solution
The method involves using activation members with teeth and grooves that form a deformation zone with a longer path length and adjustable depth of engagement, allowing for incremental stretching at a low strain rate, minimizing web damage and maintaining material properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high strain rate stretching is used for activation, then productivity is improved, but web damage increases
Solution Approach 1:
The activation process is divided into multiple stages by using a multi-tooth activation member where teeth are spaced apart. This segmentation allows different portions of the web to be activated at different rates simultaneously, enabling overall high productivity while protecting vulnerable portions from high strain rate damage.
Solution Approach 2:
Different teeth on the activation member have different spacing and engagement characteristics tailored to specific local requirements. The activation members create zones of varying deformation intensity, allowing aggressive activation in some areas while using gentler activation in other areas to prevent web damage.
2Device complexity
If conventional activation rolls with short activation path length are used, then device complexity is reduced, but manufacturing precision of web properties deteriorates
Solution Approach 1:
The activation members feature adjustable teeth and grooves that can be dynamically configured to create variable depth of engagement zones. This dynamic adjustability allows precise control over the activation process and web property modification while maintaining a compact apparatus design.
Solution Approach 2:
The invention transitions from a simple one-dimensional rolling contact to a multi-dimensional engagement system with teeth and grooves interacting in multiple directions. This creates a more complex deformation zone that provides superior control over web properties while the modular tooth structure keeps the overall device compact.
3Reliability
If low strain rate stretching is used to avoid web damage, then web integrity is improved, but productivity decreases
Solution Approach 1:
The activation members are designed with pre-configured teeth and grooves that establish the deformation pattern before the web enters the activation zone. This preliminary configuration ensures that the web experiences controlled, low strain rate activation from the start, maintaining integrity while enabling sustained processing speed through the continuous action of multiple teeth.
Solution Approach 2:
Multiple teeth on the activation member are spaced to ensure continuous engagement with the web throughout the rotation cycle. This continuous action maintains consistent low strain rate activation across the entire web surface, ensuring both web integrity and sustained productivity without interruption.
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 enables the stretching of web materials at higher speeds without causing damage, maintaining the integrity and desirable properties of the web, such as strength and softness, while accommodating longer deformation zones without the need for impractically large equipment.
Implementation Method 1
activation members with teeth and grooves that form a deformation zone with a longer path length and adjustable depth of engagement, allowing for incremental stretching at a low strain rate
Data Source
Figure 1A
Figure 1B
Figure 2
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 (114) and a single activation member (112) wherein the activation belt and single activation member comprise a plurality of teeth (124) and grooves (126) that complement and engage one another at a depth of engagement in a deformation zone (120). The depth of engagement can be controlled to increase linearly over at least a portion of the deformation zone such that a web (116) interposed between the activation belt and the single activation member in the deformation zone is incrementally stretched at a low rate of strain.