Asymmetric Male Touch Fastener Head Shape for Loop Engagement
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Solution Overview
Problem
Existing male touch fastener products face challenges in engaging with irregularly shaped fibrous loops, particularly in personal care products like disposable diapers, due to uniform engagement characteristics that do not optimize peel and shear performance across varying loop heights and diameters.
Innovation Solution
The development of male touch fastener products with resin-based fastener elements featuring irregular, asymmetric heads with distinct engagement characteristics, including different distances from the centroid and varying perimeter curvatures, allowing for enhanced engagement with non-uniform fibrous loops by providing different fastening properties in different orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform engagement characteristics are used for fastener elements, then manufacturing is simpler, but engagement performance with irregular fibrous loops is insufficient
Solution Approach 1:
The patent applies asymmetry by designing fastener element heads with non-uniform shapes that have different engagement characteristics at different locations. The heads feature varying distances from the centroid to the perimeter (at least three different distances differing by at least 10%), creating asymmetric engagement properties that optimize interaction with irregularly shaped fibrous loops in personal care products.
Solution Approach 2:
The patent implements local quality by ensuring that different regions of the fastener element head have distinct engagement characteristics. Specifically, the head is designed so that different portions at varying distances from the centroid provide different engagement properties, allowing localized optimization for engaging with fibrous loops of varying heights and diameters across the fastener surface.
2Reliability
If fastener elements engage all fibrous loops uniformly, then engagement consistency is achieved, but peel and shear performance optimization is limited
Solution Approach 1:
The patent uses asymmetry to create fastener element heads with non-uniform geometries that provide varying engagement characteristics across different locations. This asymmetric design enables the fastener to optimize peel and shear performance by creating deliberate variability in engagement properties, with different head regions providing different engagement strengths and characteristics.
Solution Approach 2:
The patent applies local quality by designing the fastener element head so that specific regions have tailored engagement characteristics. The head features varying distances from the centroid to the perimeter, creating localized zones with different engagement properties that can be optimized for specific engagement requirements, thereby enhancing overall peel and shear performance through spatially varying engagement.
3Reliability
If simple fastener head shapes are used, then manufacturing precision is easier to achieve, but engagement with varying loop heights and diameters is insufficient
Solution Approach 1:
The patent implements asymmetry by designing fastener element heads with deliberately non-uniform shapes characterized by at least three different distances from the centroid to the perimeter, where these distances differ by at least 10%. This asymmetric geometry provides enhanced engagement capability with varying loop heights and diameters while maintaining manufacturability through defined geometric parameters.
Solution Approach 2:
The patent applies local quality by creating fastener element heads where different regions have distinct engagement characteristics based on their distance from the centroid. This localized variation in head geometry allows the fastener to effectively engage with fibrous loops of varying dimensions, with each region of the head optimized for specific engagement requirements.
Data Source
Figure 1~1A
Figure 2~3
Figure 4~5
AI summary
A touch fastener product having a base sheet (12) with a resin side surface (16) and a male touch fastener element (14) having a head (20) disposed at a distal end of a resin stem and overhanging the base sheet. The head has an overall shape, as projected in a plane parallel to the base sheet, with a perimeter (42) that defines spaced apart extremities (48) corresponding to head sections of different engagement characteristics and disposed at different distances (50) from a centroid (40) of the overall shape. In one example, the head projection has a polygonal perimeter consisting of straight edges (54) of differing lengths connected at radiused corners. In another, the perimeter comprises an unbroken series of at least three arc segments (44) of different curvatures, with centers of the arc segments disposed at different distances from the centroid.