Fastener With Integrated Compression-Limiting Sleeve
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Solution Overview
Problem
Conventional fastener systems require a secondary staking operation and result in significant scrap and uncontrollable tolerances, with limited ability to adjust column strength, when attempting to limit compression.
Innovation Solution
A fastener system comprising a threaded bolt or screw with a cold-headed compression-limiting sleeve and a retainer, where the sleeve is not staked to the fastener, allowing for tighter tolerances and adjustable column strength without additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a stamped sleeve or bushing is staked to a threaded fastener to limit compression, then compressive forces are absorbed by the sleeve, but a secondary staking operation is required and manufacturing complexity increases
Solution Approach 1:
The compression-limiting member is integrated directly into the fastener body as a unified component, eliminating the need for separate staking operations. The fastener is formed with a head, shaft, and integrated compression-limiting member in a single manufacturing process, combining multiple functions into one component.
Solution Approach 2:
The fastener serves multiple functions simultaneously: it provides threading for fastening, structural support through the shaft, and compression limitation through the integrated member. This multi-functional design eliminates the need for separate compression-limiting components and their associated assembly operations.
2Strength
If a stamped sleeve or bushing is used to limit compression, then compressive forces are absorbed, but significant scrap is generated and material waste increases
Solution Approach 1:
The manufacturing process forms the compression-limiting member through plastic deformation of the fastener material itself rather than stamping separate sleeves that generate scrap. The material is redistributed and formed into the desired shape without being discarded, significantly reducing waste.
Solution Approach 2:
The fastener is formed as a composite structure with different functional zones (head, shaft, compression-limiting member) all made from the same material but with different geometric configurations optimized for their specific functions, eliminating the need for separate stamped components.
3Strength
If a stamped sleeve or bushing is used to limit compression, then compressive forces are absorbed, but tolerances cannot be closely controlled and manufacturing precision decreases
Solution Approach 1:
The compression-limiting member is formed during the initial fastener manufacturing process before final assembly. The plastic deformation and forming operations are performed while the material is still in a workable state, allowing for precise dimensional control that would be difficult to achieve through subsequent stamping operations.
Solution Approach 2:
The manufacturing process utilizes controlled plastic deformation to achieve precise dimensional tolerances. By adjusting forming parameters such as pressure, temperature, and tooling geometry, the compression-limiting member can be formed with tight tolerances that are difficult to achieve with stamping operations.
4Strength
If a stamped sleeve or bushing is used to limit compression, then compressive forces are absorbed, but the column strength cannot be easily adjusted and adaptability decreases
Solution Approach 1:
The fastener design allows for easy adjustment of column strength by modifying geometric parameters such as wall thickness, length, and cross-sectional area of the compression-limiting member. These dimensional changes can be made during the forming process to adapt to different application requirements without changing the fundamental design or material.
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 system effectively absorbs compressive forces without secondary staking, reduces scrap, and allows for precise control of column strength through variations in sleeve wall thickness and hardness, enhancing assembly efficiency and component alignment.
Implementation Method 1
the sleeve or bushing absorbs compressive forces that otherwise would have to be absorbed by the first workpiece
Implementation Method 2
a retainer which generally retains the compression-limiting sleeve on the fastener
Data Source
AI summary
A fastener system that includes a fastener, a compression-limiting sleeve, and a retainer which generally retains the compression-limiting sleeve on the fastener. By providing that the compression-limiting sleeve is not staked to the fastener, existing technology can be used, and no extra staking processing step needs to be performed. The fastener may comprise a conventional metal threaded screw or bolt, possibly having a recess in its head for receiving a driver. Preferably, the compression-limiting sleeve is cold headed as opposed to being stamped, and preferably includes a counter bore which assures that an end of the retainer is below an end surface of the compression-limiting sleeve. Preferably, the retainer is formed of a thermoplastic elastomer or another suitable material.