Slide Fastener Element Geometry for Strength Without Sliding Interference
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Solution Overview
Problem
Conventional slide fasteners with ribs on the inner surface of the engaging concave portion can interfere during engagement, leading to poor sliding properties.
Innovation Solution
A metal element design with a tapered engaging convex portion and hollowed, tapered engaging concave portion, featuring a protrusion on the concave portion's side, with specific width and height ratios and a controlled relative rotation angle, to enhance puncture strength while maintaining smooth engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rib is provided on the inner surface of the front end wall of the engaging concave portion, then puncture strength is improved, but sliding property deteriorates due to interference between the engaging convex portion and the rib
Solution Approach 1:
The rib structure is completely removed from the front end wall of the engaging concave portion. Instead, a protrusion is formed on the inner surface of the engaging concave portion at a position away from the front end wall, specifically on the side surface closest to the leg portions. This extraction of the rib structure eliminates the interference problem while maintaining the reinforcing function through the protrusion geometry.
Solution Approach 2:
The reinforcement structure is moved from the front end wall area to the side surface area of the engaging concave portion. The protrusion extends in the depth direction of the concave portion rather than protruding from the front end wall, changing the spatial dimension of the reinforcement feature to avoid interference with the engaging convex portion during sliding.
2Strength
If the engaging concave portion is made deeper to improve engagement strength, then puncture strength is improved, but the engaging convex portion may get caught on the front end wall during sliding
Solution Approach 1:
The engaging concave portion is designed with non-uniform depth characteristics. The bottom of the concave portion has a smaller circumferential length than the opening, creating a tapered shape. Additionally, a protrusion is formed on the side surface, creating local variations in depth that provide reinforcement without requiring the entire concave portion to be deeply engaged, thus preventing catching during sliding.
Solution Approach 2:
The engaging concave portion is designed with a tapered curved shape where the circumferential length decreases toward the bottom. This curved, tapered geometry allows the engaging convex portion to slide smoothly while maintaining engagement strength, as the gradual change in cross-sectional area prevents sudden catching or binding during the sliding motion.
Data Source
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AI summary
PROBLEM To provide an element and slide fastener with which it is possible to improve up-thrusting strength while maintaining sliding properties during engagement. SOLUTION The present invention is characterized by comprising: a head part 11 in which are formed an engagement convex part 13 that projects from one surface of the head part 11, and an engagement concave part 14 that is formed on the rear side of the engagement convex part 13 on the other surface of the head part 11; and a pair of leg parts 12 that extend from the head part 11, a projecting part 16 that projects toward the inner side of the engagement concave part 14 being formed on the leg part 12 side of the engagement concave part 14.