Curved Injection Molded Hook Stress Distribution
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Solution Overview
Problem
Existing injection molded hook straps suffer from stress concentration, destruction of hooks and loops, insufficient lateral engagement strength, and fail-to-engage issues due to inflexible hook bodies and improper hook arrangement, leading to weakened fastening functionality and reduced lifespan.
Innovation Solution
The design incorporates a hook body with increased curvature and strategically arranged hooks, where the hook body, neck, and end are defined by specific circular relationships to distribute stress evenly and enhance engagement strength, and the hooks are arranged to increase engagement probability across different directions and angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the hook body is made rigid and perpendicular to the substrate, then the hook structure is simple and manufacturing is easy, but stress concentration occurs at the hook neck causing plastic deformation and reduced lifespan
Solution Approach 1:
The hook body is designed with a curved shape instead of being perpendicular to the substrate. The curvature radius is specifically controlled to be 0.5-2.0 times the hook height, which allows the hook to flexibly deform under load, distributing stress away from the hook neck and preventing plastic deformation while maintaining manufacturing feasibility
Solution Approach 2:
The patent optimizes specific geometric parameters including the curvature radius (0.5-2.0 times hook height), hook arm thickness (0.3-0.8 times hook height), and neck thickness (0.2-0.5 times hook height) to achieve the right balance between flexibility for stress distribution and structural integrity for durability
2Reliability
If the hook body is made flexible with increased curvature, then stress distribution is improved and plastic deformation is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific parameter ranges (curvature radius 0.5-2.0 times hook height, hook arm thickness 0.3-0.8 times hook height, neck thickness 0.2-0.5 times hook height) that provide a balance between achieving adequate flexibility for stress distribution and maintaining feasibility for injection molding manufacturing processes
3Area of stationary object
If hooks are arranged densely on the substrate, then fastening coverage is improved, but engagement strength decreases due to hook interference and fail-to-engage issues
Solution Approach 1:
The hook arms are designed to extend in multiple directions (not just perpendicular to the substrate) with specific angular orientations. This multi-directional arrangement allows hooks to engage with loops from various angles, increasing engagement probability and strength while maintaining reasonable density for adequate fastening coverage
4Adaptability or versatility
If the hook arm length and curvature are increased to improve engagement from different directions, then multi-directional engagement is enabled, but the hook becomes more prone to lateral pulling forces and deformation
Solution Approach 1:
The patent optimizes the hook arm length (0.8-1.5 times hook height) and curvature radius (0.5-2.0 times hook height) to achieve adequate angular coverage for multi-directional engagement while maintaining sufficient structural rigidity. The neck thickness (0.2-0.5 times hook height) is specifically controlled to provide lateral support and prevent excessive deformation under side loads
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
This solution prevents plastic deformation, prolongs the hook strap's effective lifetime, and provides uniform and strong fastening strength, enabling effective engagement and disengagement without lateral pulling forces, thus addressing the limitations of traditional injection molded hooks.
Implementation Method 1
the disengaging force will concentrate at the hook neck 4 because the hook body 2 stiffer than the hook neck 4, and this in turn will cause the hook neck 4 and hook end 5 to deform to a degree that exceeds the yield strength of the plastic material of the hook and thus produces plastic deformation
Data Source
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AI summary
The present invention provides a novel hook (10) and an injection molded hook strap (20) of a mechanical fastener including the hook. The hook (10) of the present invention can effectively mitigate/eliminate the stress concentration and plastic deformation problem of the injection molded hook and the destruction problem of the injection molded hooks and loops by redesigning the mutual structural relationship between the curvature of the hook body (11) and the neck portion (16) of the curved hook arm (13) and the hook end (15), so as to provide the functionalities of prolonging the effective lifetime of the hooks and the loops, extending the engaging duration between the hooks and the loops, and enhancing the engagement strength between the hooks and the loops.