Asymmetric Linear Slide Fastener Element Design
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Solution Overview
Problem
Conventional linear slide fasteners with coil-like elements require larger sizes due to equal formation of inverted and coupling head portions, leading to resource waste and increased costs, and lack efficient protection and engagement of fixing threads during sliding motion.
Innovation Solution
The design incorporates a concave portion on the coupling head with specified height and width settings, a convex portion between leg portions, and a core thread to prevent thread escape and ensure smooth engagement, allowing for a smaller fastener size while maintaining effective thread protection and engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inverted portion is formed in equal size to the coupling head, then the sewing thread is protected, but the fastener element size increases leading to resource waste
Solution Approach 1:
The patent applies local quality by providing sewing thread protection only where needed - in the concave portion on the coupling head side - rather than uniformly protecting the entire fastener element. This allows the inverted portion to be smaller while maintaining adequate thread protection in the critical area.
Solution Approach 2:
The patent employs asymmetry by making the inverted portion smaller than the coupling head, breaking the conventional symmetric design. The coupling head retains full protection features while the inverted portion is minimized, creating an asymmetric structure that reduces overall size while maintaining necessary protection.
2Loss of substance
If the fastener element size is reduced, then resource consumption decreases, but the engagement effectiveness may be compromised
Solution Approach 1:
The patent applies parameter changes by optimizing specific dimensional parameters - setting the inverted portion height to 0.5-1.5mm and the concave portion depth to 0.3-1.0mm. These parameter adjustments maintain engagement effectiveness while minimizing material consumption.
Solution Approach 2:
The patent segments the protection function into two parts: the concave portion on the coupling head for primary thread accommodation, and the smaller inverted portion for secondary protection. This segmentation allows reduced material usage while maintaining engagement effectiveness.
3Reliability
If the concave portion depth is increased to better accommodate the sewing thread, then thread protection improves, but the fastener element height increases
Solution Approach 1:
The patent applies parameter changes by optimizing the concave portion depth to a specific range (0.3-1.0mm) that provides adequate thread accommodation without excessive height increase. This parameter optimization balances thread protection needs with overall size constraints.
Data Source
AI summary
The invention provides a linear slide fastener wherein a concave portion accommodating a fixing thread for fixing a fastener tape is provided on a top face of an upper leg portion of a coil-like/zigzag-like linear fastener element, when dimensions from a bottom face of a lower leg portion to a top face of the upper leg portion on a coupling head side, at the concave portion and on an inverted portion side are assumed to be H1, H2 and H3, a setting condition of H1>H3>H2 is satisfied and when dimensions from a bottom face of the upper leg portion to a top face of the lower leg portion within a gap portion on the coupling head side, at a convex portion and on the inverted portion side are assumed to be H4, H5 and H6 respectively, a setting condition of H4>H6>H5 is satisfied.