Blind Rivet Nut Thread Geometry for Lower Mass Fastening
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Solution Overview
Problem
Existing blind rivet nuts are heavy, making them unsuitable for applications where weight reduction is critical, such as in aircraft or vehicle construction, and they often require a long threaded section to maintain strength, which increases mass.
Innovation Solution
A blind rivet nut design with a short internal thread, a maximum of four complete threads, and a high-strength material with a favorable elastic limit to elongation ratio, combined with a tapered peripheral wall and a non-cylindrical shape on the rivet sleeve, reduces the mass while maintaining strength by distributing load evenly across all thread turns and allowing a thinner wall thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the threaded section is made long to maintain strength, then the load-carrying capacity is improved, but the mass of the blind rivet nut increases
Solution Approach 1:
The patent applies parameter changes by modifying the thread pitch to differ from standard threads by at least 2%, creating a 'thread error' that causes tension between external and internal threads. This distributes forces more evenly across all thread turns, allowing the threaded section to be shorter while maintaining load-carrying capacity, thus reducing mass without sacrificing strength
Solution Approach 2:
The patent applies local quality by using a tapered peripheral wall design where the wall thickness varies along the length of the rivet sleeve. The wall thickness is smaller in sections where less strength is needed and larger where required, optimizing the distribution of material to reduce overall mass while maintaining necessary strength characteristics
2Strength
If the wall thickness is increased to strengthen the blind rivet nut, then the strength is improved, but the mass increases
Solution Approach 1:
The patent applies local quality through the tapered peripheral wall design where wall thickness is optimized locally - thinner where not needed for strength (reducing mass) and thicker where structural integrity is required (maintaining strength), achieving an optimal balance between mass and strength
Solution Approach 2:
The patent applies curvature through the tapered peripheral wall configuration that curves or angles toward the threaded section, creating a streamlined shape that reduces material usage while maintaining structural strength through geometric optimization
3Adaptability or versatility
If the internal thread has standard pitch, then compatibility with standard screws is improved, but the load distribution across thread turns is uneven
Solution Approach 1:
The patent applies parameter changes by deliberately deviating the thread pitch from standard values by at least 2%, creating a controlled 'thread error' that generates tension between mating threads. This ensures all thread turns engage and carry load evenly, improving load distribution while maintaining sufficient compatibility with appropriately designed external threads
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 design achieves a mass reduction of up to 50% with comparable strength, enabling a lighter blind rivet nut that maintains load-carrying capacity and facilitates easier manufacturing while forming a larger closing head with reduced surface pressure.
Implementation Method 1
At least in the area of the setting head and/or the deformation area, the rivet sleeve preferably has a material in which the ratio between the elastic limit and the elongation at break is at least 10%, preferably at least 12%
Implementation Method 2
When the blind rivet nut is set, an area that adjoins the setting head is at least partially inserted into the material to be joined and is then stabilized radially outwards by the material to be joined
Implementation Method 3
A threaded mandrel is screwed into the internal thread of the threaded section and a tensile force is exerted on the threaded mandrel, so that the closing head is formed on the 'blind side' of the component. The deformation area deforms to form the closing head
Data Source
Figure 1a~3b
Figure 4a~4c
Figure 5a~6d
AI summary
A blind rivet nut (1) is specified, comprising a rivet sleeve (2) which has a setting head (3), a deformation area (4) for forming the closing head, and a threaded section (5) with an internal thread (6). The aim is to provide a low-mass blind rivet nut. For this purpose, the internal thread (6) is designed to have a maximum of four complete thread turns.