Push-On Spring Nut With Residual Clamp Load and Easy Removal
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Solution Overview
Problem
Current micro fastening techniques fail to meet the requirements of generating a residual clamp load, ease of installation, and removability, particularly in micro assemblies, as they either form permanent joints or require complex installation tools.
Innovation Solution
A micro-sized fastener with spring arms and downward-facing fingers that can be installed with axial pressing, providing a residual clamp load and easily removable using a tool like snap ring pliers, featuring a unitary body of resilient material with specific geometric design for easy assembly and disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rivets or spot welding are used to attach panels, then a permanent joint is formed providing strong connection, but the parts cannot be replaced or repaired easily
Solution Approach 1:
The fastener uses resilient arms that can dynamically change their grip state. During installation, the arms are compressed to allow passage over the shaft. Once positioned, the arms resiliently expand to grip the shaft firmly. For removal, the arms can be compressed again to release the grip, enabling easy removal and reuse of the fastener while maintaining strong connection during service.
Solution Approach 2:
The fastener changes its mechanical parameters (specifically the compression state of resilient arms) to transition between installation, service, and removal modes. By applying axial force, the arms are compressed to a state allowing easy installation. In the service state, the arms maintain their expanded gripping force. During removal, the arms are compressed again to release the grip, enabling parameter-based control of joint strength and removability.
2Ease of repair
If threaded fasteners are used, then a removable joint is provided allowing parts to be replaced, but complex installation tooling and torque application are required
Solution Approach 1:
The invention extracts the complex threading mechanism from the fastener design, replacing it with a simple push-on structure. The fastener body without threads can be easily pushed over the shaft using only axial force. The complexity of torque application and threaded engagement is removed entirely, while removability is maintained through the compressible resilient arms that can be released with simple pliers.
Solution Approach 2:
The complex mechanical system of threaded engagement and torque application is replaced with a simpler resilient arm compression system. Instead of using threads to create friction-based grip requiring rotational force, the invention uses directly compressible resilient arms that grip through elastic deformation, achievable with simple axial pressing motion.
3Ease of operation
If simple axial insertion is used for installation, then ease of installation is improved, but the ability to maintain residual clamp load is reduced
Solution Approach 1:
The fastener utilizes parameter change in the resilient arms' compression state. During simple axial insertion, the arms are compressed along the axis of the shaft. This compression, when released, transforms into radial gripping force against the shaft. The same resilient arms continue to maintain this gripping force as residual clamp load during service, achieving both easy installation and sustained clamping through parameter transformation.
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 fastener simplifies assembly by axial insertion, provides a clamp load between components, and allows easy removal, improving upon traditional fastening methods like riveting and welding by enabling non-permanent attachment and easy replacement in micro assemblies.
Implementation Method 1
spring arms formed by bent tabs which deflect when pressed onto and grip the pin or other mating component between jaws of the arms
Implementation Method 2
Downward facing fingers located around the periphery of the fastener flex when they come into contact with another portion of the mating component. This creates a residual clamp load between the fastener and the component
Implementation Method 3
The top has two through-holes, each located on an opposite side of the opening adjacent its longer sides along the minor axis. The holes are adapted to receive the application of opposing inwardly directed forces whereby the fastener is distorted such that the arms spread apart
Data Source
AI summary
A fastener is installed by applying an axial pressing force onto a mating component such as a round pin or a square tab. The fastener includes spring arms formed by bent tabs which deflect when pressed onto and grip the pin or other mating component between jaws of the arms making the fastener resistant to being pulled off. Downward facing fingers located around the periphery of the fastener flex when they come into contact with another portion of the mating component. This creates a residual clamp load between the fastener and the component. The fastener can easily be removed using a tool similar to snap ring pliers or needle nose pliers. Two holes on opposite sides of the fastener allow the part to be squeezed and deformed into an oval shape. This action disengages the arms and allows the fastener to slide off the mating component without resistance.