Low-Profile Cam Locking Fastener for Vibration Resistance
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Solution Overview
Problem
Existing cam locking fasteners have a high profile due to thin wall construction, limiting their use in applications with small clearance dimensions, and screws in vibrating environments tend to back out, leading to potential machinery failures.
Innovation Solution
A low-profile cam locking fastener design featuring a nut with a tubular skirt and a locking washer, both with wedge locking action features, ensuring secure engagement and resistance to vibration-induced loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thin wall construction is used to facilitate swaging operation, then the swaging operation can be performed, but the fastener height to washer diameter ratio increases to 0.65 or higher, resulting in a high profile that prevents use in applications with small clearance dimensions
Solution Approach 1:
The patent changes the wall thickness parameter from thin to thick construction, which enables the swaging operation to be performed effectively while maintaining a reduced fastener height profile. The thick wall construction (ratio of 0.45 or less) provides sufficient material for the swaging operation to flare over and retain the washer while keeping the overall height low enough for small clearance applications.
2Length of stationary object
If thick wall construction is used to reduce fastener profile, then the fastener height to washer diameter ratio decreases to 0.45 or less, but the swaging operation becomes difficult to perform
Solution Approach 1:
The patent optimizes the wall thickness parameter to a specific range (thick wall construction with height to diameter ratio of 0.45 or less) that provides sufficient material thickness for the swaging operation to flare over effectively while maintaining the reduced profile. This parameter optimization resolves the contradiction by finding the optimal thickness that enables both low profile and manufacturability.
3Ease of manufacture
If conventional nut and washer design is used, then the fastener can be manufactured, but vibration causes the nut to rotate loose and back out
Solution Approach 1:
The patent merges the nut and washer into a single integrated fastener component, eliminating the separate washer that can rotate independently. The integrated design includes a cam surface with wedge locking action features that prevent the fastener from backing out under vibration, while maintaining manufacturability through the thick wall construction that enables effective swaging operation.
Solution Approach 2:
The patent converts the harmful effect of vibration into a beneficial self-tightening mechanism. The cam surface with wedge locking action features is designed so that vibration-induced movement increases the preload on the cam, which in turn increases the locking force and prevents the fastener from loosening further.
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 provides a secure, low-profile fastening solution that effectively prevents back-out in high-vibration applications by utilizing wedge locking action features, ensuring reliable operation in environments where traditional fasteners fail.
Implementation Method 1
cam surface comprising wedge locking action fastening features
Implementation Method 2
the cam rise angle is greater than the lead angle of the thread on the bolt. As the nut rotates relative to the washer, the preload is actually increased, further locking the nut.
Data Source
AI summary
A fastener is configured for use in a high vibration application. The fastener includes a nut including a nut body including a cam surface comprising wedge locking action fastening features and a hex shape upon an outer surface of the nut body. The nut further includes a locking washer including matching wedge locking action fastening features to the wedge locking action fastening features of the cam surface and a matching hex shape upon an outer surface of the washer to the hex shape upon the outer surface of the nut body. The nut is configured to include a threaded inner surface selected according to a bolt to be fastened and a nut wall thickness selected according to a load to be applied to the nut.