Touch Fastener Stems Formed by Needling and Welding
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Solution Overview
Problem
Existing touch fastener technologies face limitations in shaping and sizing features at high speeds, particularly in molding hooks or precursor stems, which restricts the variability and effectiveness of fastening elements.
Innovation Solution
A touch fastener product with stems of resin extending at different angles from a base, where the stems are secured with weld points and have heads that overhang all sides, allowing for pseudo-random distribution and varying lengths and thicknesses, enabling flexible and efficient engagement with fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hooks or precursor stems are molded in closed cavities or formed by cutting and stretching extruded rails, then cost-effective production is achieved, but the shapes and sizes of features are limited in what can be readily molded at high speeds
Solution Approach 1:
The patent replaces traditional mechanical molding and extrusion processes with a needling process that uses mechanical needles to punch and form stems directly in the fabric base. This substitution enables greater shape and size variability while maintaining cost-effective production, as the needling process is more flexible than molded cavity constraints.
Solution Approach 2:
The invention changes the fundamental manufacturing parameter from molded geometry to needled formation, allowing stems to vary in length, thickness, and curvature. The stems can extend at different angles from the base and have varying lengths, which cannot be easily achieved through traditional high-speed molding while maintaining production efficiency.
2Ease of operation
If stems are made thin and flexible to penetrate dense fiber layers, then engagement effectiveness is improved, but manufacturing precision and consistency become more difficult to maintain
Solution Approach 1:
The needling process allows stems to self-form with natural variations in thickness and curvature as they are punched through the fabric base. The stems inherently adapt to the fabric structure, creating consistent engagement characteristics without requiring tight dimensional control during manufacturing.
Solution Approach 2:
Each stem can have local variations in thickness and curvature that are appropriate for its specific location and function in penetrating dense fiber layers. The manufacturing process accommodates these local variations rather than enforcing uniform dimensions, improving both penetration capability and functional consistency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution allows for the production of thin, flexible fastener elements that can penetrate dense fiber layers, providing stable connections and material efficiency, while avoiding the limitations of high-speed molding or extrusion.
Implementation Method 1
bases of the stems are secured to the side surface of the base at weld points in which resin of each stem is solidified in a weld with resin of the base side surface
Data Source
Figure 1~2
Figure 2A
Figure 3~3A
AI summary
A touch fastener (10) having long and thin headed stems (18) welded to and extending from, for example, a thin film (32, 74), is made by orienting thin, hollow, drawn staple fibers (58) between bristles (70) of a brush, with no more than fiber ends (66) sticking out of the brush, and then fusing a film to the fiber ends by direct welding. The fibers are then withdrawn from the brush as stems that are headed by heating their ends and allowing the resin to reform into an engageable head (20).