Asymmetric Slide Fastener Elements for Bidirectional Slider Movement
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Solution Overview
Problem
Conventional slide fasteners experience smooth slider movement only in one direction, and there is a need for a design that allows the slider to move smoothly in both directions while also providing a visible, aesthetically appealing metal element appearance for applications like leather jackets or bags.
Innovation Solution
The slide fastener element features a coupling portion with two opposite faces having engaging protrusions and recesses, a plastically bendable root portion forming a Major arc shaped groove, and a distal plate portion with reduced thickness, allowing for closer element spacing and a uniform, shiny metallic appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional slide fastener elements are used, then the slider moves smoothly in one direction, but the slider movement becomes uneven in the opposite direction
Solution Approach 1:
The fastener element features an asymmetric design where the coupling portion has different configurations on its first and second opposite faces. The first face includes a first engaging protrusion and first engaging recess, while the second face includes a second engaging protrusion and second engaging recess with different geometries. This asymmetric configuration allows the slider to engage and disengage smoothly in both directions by providing optimized contact surfaces for each direction of movement.
2Ease of manufacture
If elements are spaced further apart, then the fastener is easier to manufacture, but the metallic appearance becomes less uniform and dense
Solution Approach 1:
The invention optimizes the pitch (spacing) parameter between adjacent fastener elements to achieve a denser arrangement that provides a uniform, shiny metallic appearance. The coupling portion is designed with reduced thickness in specific regions, allowing elements to be placed closer together while maintaining manufacturability. This parameter optimization balances manufacturing ease with aesthetic requirements for visible metallic appearance.
Data Source
AI summary
A fastener element for a slide fastener includes: a coupling portion; and one single root portion either including, or being plastically bendable to include, a bent portion and a distal end portion which extends from the bent portion towards a side of the coupling portion which is closer to the fastener tape. Each face of the coupling portion includes an engaging protrusion protruding in a lengthwise direction, and an engaging recess recessed in a lengthwise direction with respect to the face, and is configured for receiving an engaging protrusion of a fastener element on the opposite stringer in a closed condition of the slide fastener.