Spring-Leg Locknut Structure for Vibration-Resistant Fastening
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Solution Overview
Problem
Existing locknuts are prone to loosening due to vibration and thermal expansion/contraction, posing safety risks and requiring separate tools for installation and removal, which increases manufacturing costs and limits their use in high-volume applications.
Innovation Solution
A locknut design featuring a nut body with a pocket containing a spring member with leg members and an apex, which applies pressure to an externally threaded member at opposed radial locations, providing a locking force without relying on plastic inserts and allowing for repeated use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional locknuts are used to prevent loosening, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The locknut is divided into two functional segments: a nut body for threading and a separate spring member for locking. The spring member includes multiple legs that can independently contact the threaded member at different radial locations, providing distributed locking force. This segmentation allows each component to be optimized independently and simplifies manufacturing.
Solution Approach 2:
The locking function is extracted from the traditional integrated locknut design and implemented through a separate spring member that can be inserted into the nut body. This extracted spring member acts as an independent locking mechanism that applies radial pressure to the threaded member, separating the locking function from the fastening function.
2Ease of manufacture
If traditional locknuts require separate tools for installation and removal, then ease of manufacture is improved, but ease of operation deteriorates
Solution Approach 1:
The spring member is designed to automatically engage and disengage from the threaded member through its elastic deformation. During installation, the spring member is compressed and then self-locks when the nut is tightened. During removal, the spring member self-releases when the nut is loosened, eliminating the need for special tools or procedures.
3Loss of substance
If locknuts are designed for repeated use, then loss of substance is reduced, but reliability may deteriorate due to wear
Solution Approach 1:
The spring member's elastic properties are optimized to maintain consistent locking force over multiple cycles. The material selection and geometric design of the spring legs ensure that elastic deformation remains within the elastic limit, preventing permanent set and maintaining reliable locking force throughout the service life of the fastener.
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 effectively prevents loosening, allows for easy installation and removal without tools, and reduces manufacturing costs, making it suitable for high-volume production while maintaining structural integrity and safety.
Implementation Method 1
A spring member having a generally-rectangularly shaped cross-section disposed within the pocket includes at least first and second leg members joined together by an apex member. The first and second leg members define respective first and second locking surfaces. The first and second locking surfaces exert pressure on the externally threaded member at respective first and second spaced-apart radial locations to develop a locking force between the nut body and the externally threaded member.
Data Source
AI summary
A locknut includes a nut body having a threaded through opening therein extending between a first end and a second end. A pocket is defined within the second end of the nut body. A spring member having a generally rectangularly shaped cross-section disposed within the pocket includes a pair of leg members joined together by an apex member. The leg members define locking surfaces. The locking surfaces exert pressure on the externally threaded member at spaced-apart radial locations to develop a locking force between the nut body and the externally threaded member.