Modular Nut Plate Assembly Radial Expansion
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Solution Overview
Problem
Conventional nut plates with fixed longitudinal lengths are unsuitable for workpieces with varying longitudinal dimensions, requiring a variety of brackets to be stocked, and existing solutions like floating nut devices are limited in their adaptability and durability.
Innovation Solution
A rivetless nut plate assembly featuring a retainer assembly with an expandable member and a tubular body that can be radially expanded to fit different workpiece sizes, using a mandrel to expand both the bushing and tubular body for a secure interference fit, allowing for installation in workpieces with varying longitudinal lengths and improving fatigue performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a one-piece expandable sleeve bracket is used, then the bracket can be installed in workpiece openings, but the fixed longitudinal length renders it unsuitable for workpieces with significantly different longitudinal lengths
Solution Approach 1:
The bracket transitions from a fixed-length one-piece design to a dynamic multi-component design where the longitudinal length can be adjusted by selecting different grip length components. The bracket assembly includes a head portion, a grip length portion with configurable length, and a flange portion, allowing adaptation to various workpiece longitudinal dimensions without requiring multiple different bracket types in inventory.
2Ease of manufacture
If conventional fixed-length brackets are used, then manufacturing and installation are straightforward, but a large variety of brackets must be kept in stock for different sized openings
Solution Approach 1:
The bracket is divided into separate configurable components including a head portion, a grip length portion, and a flange portion. This segmentation allows the grip length to be customized for different workpiece sizes while maintaining a standardized head and flange design, thereby reducing the variety of brackets needed in stock while still accommodating different opening sizes.
Solution Approach 2:
The bracket design incorporates universal elements such as a standardized head portion and flange portion that can work with various grip length configurations. This multi-functionality allows a single bracket family to serve multiple workpiece size requirements, eliminating the need to stock numerous different bracket types.
3Reliability
If the tubular body is radially expanded to fit different workpiece sizes, then a secure interference fit is achieved, but the expansion process requires additional equipment and steps
Solution Approach 1:
The bracket components are pre-configured with expansion features and geometries that facilitate the radial expansion process. The grip length portion and flange portion are designed to work together with expansion tools to achieve the desired interference fit, preparing the structure in advance to accommodate the expansion operation without requiring complex custom tooling.
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 modular nut plate assembly provides a secure fit in workpieces of different sizes, reduces the need for multiple bracket sizes, and enhances the fatigue performance of the workpiece by inducing compressive stresses through radial expansion.
Implementation Method 1
The expandable member and a tubular body of the nut retainer can be radially expanded together. For example, the expandable member in the form of a bushing can be radially expanded by a mandrel so as to radially expand the tubular body and the workpiece.
Implementation Method 2
The radially-expanded expandable member, in some embodiments, achieves high levels of expansion of the tubular body, which in turn causes sufficient expansion of the workpiece to improve fatigue performance of the workpiece.
Data Source
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AI summary
A nut plate assembly includes a nut retainer and a bushing for expanding a tubular body of the retainer. The retainer assembly is used to cold work an opening of a workpiece in order to fix the nut retainer assembly relative to the workpiece. A nut can be snapped into the retainer. A method of installation includes passing a mandrel through the bushing to radially expand the bushing into a tubular body of the retainer. The tubular body is compressed between the workpiece and bushing as the bushing is displaced radially causing corresponding radial displacement of the tubular body. The expanded bushing applies pressure to the tubular body for a desired fit between the nut retainer and workpiece.