Segmented Nut Sleeve Interface for Predictable Release Torque
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Solution Overview
Problem
Existing segmented nuts face challenges with unpredictable release torque due to galling issues and tight tolerancing requirements, leading to variability in release torque characteristics and increased manufacturing complexity.
Innovation Solution
The design incorporates a segmented nut with a sleeve and inner segments featuring a segment interface portion and sleeve interface portion that undergo deformation during rotation, allowing for a self-centering mechanism with axial retention, reducing the need for high tolerance machining and minimizing galling, while providing consistent release torque characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an interference fit is used between the inner segments and outer sleeve to prevent separation during transport and storage, then the radial constraint and assembly stability are improved, but the release torque becomes sensitive to interference fit degree and accurate tolerancing is required, increasing manufacturing complexity
Solution Approach 1:
The interface between the sleeve and segments is segmented into multiple discrete engagement points (protrusions and recesses) rather than a continuous interference fit. This segmentation allows the components to engage at specific locations, reducing the need for tight tolerances across the entire interface while maintaining assembly stability.
Solution Approach 2:
The engagement interface uses localized protrusions and recesses at specific positions rather than a uniform interference fit across the entire circumference. This local engagement approach concentrates the constraint function at discrete points, allowing larger clearance elsewhere and reducing manufacturing tolerancing requirements.
2Strength
If an interference fit is used between the inner segments and outer sleeve, then radial constraint is improved, but galling (cold-welding) issues occur during press-fitting, affecting release torque consistency
Solution Approach 1:
The continuous contact interface is divided into discrete engagement points with protrusions and recesses. This segmentation reduces the total contact area during press-fitting, minimizing the surfaces that can experience galling while still providing sufficient radial constraint through the localized engagement points.
Solution Approach 2:
The harmful continuous contact interface that causes galling is extracted and replaced with discrete engagement features. By removing the continuous sliding contact between sleeve and segments, the source of galling is eliminated while the essential radial constraint function is preserved through the protrusion-recess engagement.
3Area of stationary object
If radiused bearing surfaces are used between segments and sleeve for radial constraint, then sufficient engagement area is provided, but accurate tolerancing is required to prevent accidental disassembly during transport or storage
Solution Approach 1:
The continuous radiused bearing surface is segmented into discrete engagement points with protrusions and recesses. This segmentation allows the contact area to be concentrated at specific locations rather than distributed continuously, reducing the tolerancing requirements for surface alignment and position.
Solution Approach 2:
The engagement interface uses asymmetric protrusions and recesses with specific geometric features that provide positive engagement. This asymmetric design creates a self-aligning mechanism that reduces the need for precise tolerancing compared to symmetric radiused surfaces that require accurate concentricity.
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 design ensures predictable and repeatable release torque, reduces manufacturing costs, and enhances safety by preventing accidental disassembly during transport and storage.
Implementation Method 1
at least one of the segments having a segment interface portion, at least part of the sleeve interface portion and at least part of the segment interface portion being in engagement when the sleeve rotates relative to the inner nut during release of the segmented nut
Data Source
AI summary
A segmented nut has inner segments and an outer sleeve. Part of the sleeve interface portion and part of the segment interface portion engage when the sleeve rotates relative to the inner nut during release of the segmented nut with part of the segment interface portion at a greater distance from a central axis of the segmented nut than a minimum distance of the at least part of the sleeve interface portion from the central axis. One or more of the segments can include a retainer preventing the sleeve moving toward a free face of the segment(s). One or more of the segments can have a flange portion providing an increased working (compression) face relative to a plain segmented nut. An assembled segmented nut can include some radial freeplay for the segments to move radially whilst being retained within the sleeve prior to application of the segmented nut to a threaded bolt, stud or rod such that threading of the segmented nut onto the thread of the bolt, stud or rod removes the freeplay.