Flexible Hook-In-Hook Closure With Segmented Hooks
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Solution Overview
Problem
Existing hook-in-hook closures for plastic bags lack flexibility, causing rigidity issues and trapping small particles, which can lead to contamination and operational impairment.
Innovation Solution
A flexible hook-in-hook closure system with thinner hooks and increased spacing between them, produced using extrusion methods, allowing for better sealing and reduced particle trapping, while maintaining effective engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thick hooks are used in hook-in-hook closures, then the closure has sufficient strength and engagement reliability, but the opening loses flexibility and rigidity increases
Solution Approach 1:
The closure system is divided into multiple rows of hooks distributed across the opening. Each row contains multiple hooks spaced apart, creating a segmented structure that distributes mechanical stress across many small contact points rather than requiring each individual hook to be thick. This segmentation allows the overall closure to maintain strength while each hook remains thin enough to preserve flexibility.
Solution Approach 2:
The hook dimensions are optimized locally - each hook has a specific thickness and spacing that balances engagement reliability with flexibility. The local geometry of each hook (including head shape and engagement surface) is designed to maximize gripping strength while minimizing bulk, allowing the closure to provide sufficient holding force without creating overall rigidity in the opening.
2Reliability
If thick hooks with small spacing are used, then engagement reliability is improved, but small particles become trapped under the hooks causing contamination
Solution Approach 1:
The hook design incorporates asymmetric features including a head portion with a larger engagement surface area than the shank thickness. This asymmetry creates an engagement geometry where the hook head grips the opposing hook effectively (maintaining reliability) while the spaced arrangement and profile minimize the creation of tight crevices where particles could become trapped and retained.
Solution Approach 2:
The invention optimizes specific dimensional parameters of the hooks - the thickness, spacing distance, head dimensions, and engagement surface area - to achieve a balance where engagement reliability is maintained through proper geometric relationships while the increased spacing and optimized profiles reduce particle trapping. The parameters are tuned so that hooks engage securely without creating particle-retention zones.
3Reliability
If complex moulding methods are used to produce hooked strips, then closure functionality is achieved, but manufacturing complexity and difficulty increase
Solution Approach 1:
The hook-in-hook closure system is designed to be self-forming and self-gripping. The hooks are arranged and dimensioned so that they automatically engage with opposing hooks when the opening is closed, without requiring complex assembly operations or specialized moulding techniques. The geometric design of the hooks (with heads and engagement surfaces) allows them to self-align and self-grip, simplifying both manufacturing and operation.
Solution Approach 2:
The hooked strip design integrates multiple functions into a single component structure - the hooks provide both the sealing function (by engaging with opposing hooks) and the closure function (by preventing opening). This multi-functionality is achieved through a universal hook geometry that can be produced using standard extrusion or moulding techniques, eliminating the need for complex multi-step manufacturing processes or specialized tooling.
Data Source
AI summary
An automatic gripping closure device comprising a first element with hooks comprising a first base band and at least two first hooks originating from the first band and placed in at least one row of first hooks (9), each first hook being delimited by two faces (11, 12) that are mutually opposed and transverse to the direction of the at least one row of first hooks and at least one coupling portion (13, 14) protruding laterally from the stem, preferably at the top of the latter, while extending in a direction transverse to the direction of the row, and a second element with hooks comprising a second base band and at least two second hooks originating from the second band and placed in at least one row.