Curved Head Fastener Elements for Peel Force Ripple Reduction
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Solution Overview
Problem
Self-engaging fastener products with male-male engagement exhibit high shear and tension resistance but often experience peel force ripple and noise during disengagement, and there is a need for improvements in area fastener products for low-load applications where loop fibers are not desired.
Innovation Solution
A strip-form base of resin with an array of discrete fastener elements, each having a molded stem and a curved head that forms a crook with an overhang, providing a seamless mass and specific dimensions for optimal engagement and disengagement characteristics, including a distension overlap of at least 30% for smoother peel resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mushroom-type fastener elements with overhanging heads are used for self-engaging fastener products, then shear and tension resistance is improved, but peel force ripple and noise occur during disengagement
Solution Approach 1:
The fastener element head is formed with a curved, substantially semicircular cross-section that engages with the mating element. This curved geometry allows for progressive engagement and disengagement, reducing the sudden snap-action that causes peel force ripple and noise while maintaining the overhanging head configuration for high shear and tension resistance.
Solution Approach 2:
The invention modifies the geometric parameters of the fastener element, specifically the head shape and dimensions, to optimize engagement characteristics. By adjusting the curvature radius, head width, and stem dimensions, the patent achieves smooth peel disengagement while preserving the high strength properties of the mushroom-type configuration.
2Strength
If fastener elements are arranged with sufficient density for self-engaging products, then engagement strength is improved, but manufacturing complexity increases
Solution Approach 1:
The fastener elements are molded as a unitary structure with the base material, integrating the stem and head into a single seamless component. This merging of the fastener element with the base simplifies manufacturing by eliminating separate assembly steps while allowing for high-density arrangements that improve engagement strength.
Solution Approach 2:
The molded fastener element serves multiple functions: the stem provides structural support and anchoring, the curved head provides engagement surfaces, and the integrated design allows for both high-density packing and simplified manufacturing in a single component.
3Ease of operation
If the curved head protrudes beyond the stem to form an overhang, then engagement smoothness is improved, but the fastener element geometry becomes more complex
Solution Approach 1:
The head is formed with a curved, substantially semicircular cross-section that naturally creates the overhanging geometry. This curved shape provides smooth engagement surfaces that reduce peel force ripple while the regular geometric form simplifies the molding process compared to more complex asymmetric designs.
Solution Approach 2:
The fastener element features asymmetric geometry with the curved head protruding beyond the stem to create an overhang. This asymmetry is strategically designed to provide smooth engagement characteristics on one side while maintaining structural integrity, and the consistent asymmetric pattern across all elements simplifies manufacturing through standardized molding.
Data Source
AI summary
A molded area fastener product, such as a self-engaging fastener, has a strip-form base of resin with a broad surface from which an array of discrete fastener elements extends. The fastener elements each include a molded stem extending from the broad surface of the base to a curved head that extends toward a front side of the fastener element, forms a crook and ends in a distal tip. In some examples the curved head protrudes beyond the stem on the back side of the fastener element to form an overhang defined by an overhang surface of the head directed toward the base, and the crook is defined in part by an underside head surface that overhangs a lower portion of the stem. In some examples the fastener elements are arranged to provide a high distension overlap when mated with an identical fastener product.