Threaded Bush Fastening Device for Plastics One-Sided Installation
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Solution Overview
Problem
Existing mechanical fastening devices for plastic materials often require complex installation processes, limited bearing capability, and may not be suitable for one-sided installation without additional fastening mechanisms.
Innovation Solution
A fastening device comprising a metallic threaded bush with a coarse trapezoidal thread on the outside and a standard metric thread on the inside, which is inserted into a cavity with complementary threads cut into the plastic material using a tapered tool, leveraging the elasticity of the plastic to achieve secure engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional expansion plug with trapezoidal threads is used, then the fastening device can be installed in pre-drilled holes, but the installation process requires complex operations and multiple components
Solution Approach 1:
The patent combines the expansion plug and the fastening element into a single integrated component. The hollow screw contains both the external threads for engagement with the plastic material and the internal threads for receiving a fastener, eliminating the need for separate expansion plugs and reducing installation complexity
Solution Approach 2:
The hollow screw serves multiple functions simultaneously: it acts as both the expansion element and the fastening element. The external trapezoidal threads provide expansion and anchoring functionality, while the internal metric threads provide fastener reception, making the device universal for various fastening applications
2Ease of operation
If a self-tapping plate anchor with drilling part is used, then installation without pre-drilled holes is enabled, but the device requires action from both sides of the arrangement
Solution Approach 1:
The patent extracts the drilling function from the fastening device, relying on the pre-drilled hole preparation instead. This allows the hollow screw to be installed from one side only, as it不需要 to perform both drilling and fastening operations, simplifying the installation process while maintaining effectiveness
3Strength
If a hollow screw with tapered threads is used, then bearing capability is improved, but the threads are arranged at an acute angle which may reduce engagement stability
Solution Approach 1:
The patent applies different thread geometries to different locations on the hollow screw. The external threads are trapezoidal and tapered for optimal engagement with the plastic material and expansion, while the internal threads are standard metric for reliable fastener reception. This local differentiation of thread properties optimizes both bearing capability and engagement stability
4Strength
If a holding pin with projecting ribs is used, then frictional engagement is enhanced, but the installation requires pressing or driving which increases operation complexity
Solution Approach 1:
The patent replaces the mechanical pressing or driving installation method with a threading-based installation system. The hollow screw is installed by rotating it into the pre-drilled hole, allowing the trapezoidal external threads to cut and expand the plastic material, creating frictional engagement through thread engagement rather than through direct mechanical force application
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 enables easy one-sided installation, enhances bearing capability, and provides strong frictional engagement to prevent loosening, even under maximum momentum loads, while avoiding plastic material cracking within its elasticity limits.
Implementation Method 1
leveraging the elasticity of the plastic to achieve secure engagement
Implementation Method 2
The coarse thread on the outside of the bush and the complementary thread of the cavity of the plastic material are engaged by compression and/or friction
Data Source
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AI summary
Fastening device for plastics comprising a threaded bush (30), arranged with a coarse thread (31) on the outside of the bush and a standard metric thread (32) on the hollow inside of the bush. The bush (30) is introduced into a cavity in the plastic which is arranged with threads complementary to those of the bush. Compression and friction between the complementary threads keep the bush in place. A utility can be screwed into the standard metric thread on the hollow inside of the bush and full momentum applied on the utility. A method for bolting the fastening device and an article comprising such a bolted fastening device are contemplated.