Helical Wire Lock Nut for Consistent Prevailing Torque
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Solution Overview
Problem
Existing locking fasteners, such as those using Vespel™ inserts, are expensive, difficult to install, prone to damage, and have limited reusability, with inconsistent torque values and high material costs, making them less than fully acceptable for applications requiring vibration and temperature resistance.
Innovation Solution
A torque control fastener system featuring a serrated nut with a helical wire insert, where the nut and insert have specific hardness and thermal expansion relationships, allowing for precise torque control and improved durability, with a reusable prevailing torque feature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Vespel™ inserts are used for locking fasteners, then vibration and temperature resistance is improved, but material cost increases and installation difficulty increases
Solution Approach 1:
The patent replaces expensive Vespel™ inserts with a disposable plastic locking insert that is molded directly into the nut. This insert is designed to be inexpensive and easily replaceable, eliminating the need for complex installation procedures while maintaining adequate performance for the application lifecycle.
Solution Approach 2:
The locking insert is integrated directly into the nut body through molding, combining what were previously separate components (nut and locking insert) into a single unified part. This eliminates the need for separate installation steps and reduces assembly complexity.
2Reliability
If Vespel™ inserts are used for locking fasteners, then vibration and temperature resistance is improved, but material cost increases
Solution Approach 1:
The patent substitutes expensive proprietary Vespel™ material with an inexpensive plastic material that is molded into the nut. The locking insert is designed to be cost-effective while providing sufficient performance, and can be easily replaced if needed without significant cost penalty.
Solution Approach 2:
The nut body and locking insert are formed as a composite structure through molding, combining the structural properties of the nut with the locking functionality of the plastic insert. This integrated composite approach reduces overall material costs compared to using expensive proprietary materials.
3Reliability
If resilient inserts are used for locking fasteners, then locking torque is provided, but the inserts are easily damaged during installation and cannot be reused
Solution Approach 1:
The locking insert is designed as a disposable component that is inexpensive enough to replace if damaged during installation or after removal. This eliminates the concern about damage during installation, as the insert can be easily replaced without significant cost or complexity.
Solution Approach 2:
The locking functionality is separated into a distinct insert component that can be independently replaced. This segmentation allows the insert to be designed for easy replacement while the main nut body remains intact and reusable.
4Reliability
If Vespel™ inserts are used for locking fasteners, then locking torque is provided, but installation difficulty increases
Solution Approach 1:
The locking insert is molded directly into the nut body, combining the nut and locking mechanisms into a single integrated component. This eliminates the need for separate installation steps for the locking insert, making installation as simple as threading the nut onto the bolt.
Solution Approach 2:
The integrated locking insert is designed to be inexpensive and easily replaced if needed, eliminating the complexity of installing proprietary inserts while maintaining adequate locking torque performance for the application.
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 system provides consistent torque values over multiple cycles, enhances tensile strength, and reduces material costs while maintaining reliability in harsh environments, offering improved assembly and maintainability.
Implementation Method 1
The serrations are configured to cooperate to resist rotation of the cap relative to the nut body
Implementation Method 2
a helical wire insert is used in conjunction with a dissimilar material to form the locking fastener
Data Source
AI summary
A torque control fastener system having a fastener nut, a helical wire insert, and a shaft, where the nut and helical wire insert have unique hardness and coefficient of thermal expansion relationships that produce improved performance.