Polymeric Coupling Nut Interference Fit for Vibration Resistance
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Solution Overview
Problem
Coaxial cable connectors face issues with undesired loosening due to twisting forces and material costs, particularly in environments with vibration, temperature variation, and moisture, where metal components contribute to weight and cost, and polymeric materials exhibit creep characteristics reducing long-term retention.
Innovation Solution
Incorporating a thread locking feature with an interference fit between the connector body and coupling nut, using a polymeric coupling nut and a metallic connector body, along with additional features like angled guide edges and deflection grooves, to create a secure and cost-effective connection resistant to unthreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal components are used for connector body and coupling nut, then strength and reliability are improved, but weight and material cost increase
Solution Approach 1:
The patent uses a polymeric coupling nut (Nylon 6/6 with 30% glass fiber reinforcement) combined with a metallic connector body, creating a composite construction that reduces weight and cost while maintaining sufficient strength through the interference fit mechanism and glass-reinforced polymer properties
2Weight of moving object
If polymeric materials are used for coupling nut, then weight and cost are reduced, but creep characteristics reduce long-term retention
Solution Approach 1:
The coupling nut is made from glass fiber-reinforced Nylon 6/6, where the glass fibers provide dimensional stability and resistance to creep while the polymer matrix provides weight reduction and cost benefits, achieving long-term retention without metal
Solution Approach 2:
The patent modifies the polymer material properties by using glass fiber reinforcement and selecting specific durometer hardness (70-90 Shore D) to enhance creep resistance and maintain threading retention over time while keeping the polymeric material advantage
3Ease of operation
If threaded connection is designed for easy assembly without torque wrenches, then ease of operation is improved, but resistance to unthreading under vibration may be reduced
Solution Approach 1:
The patent creates a localized interference fit zone between the coupling nut and connector body where the polymeric material is compressed between the positive stop and the leading edge of the outer conductor, providing vibration resistance at the critical connection point while allowing easy assembly elsewhere
Solution Approach 2:
The interference fit design pre-compresses the polymeric coupling nut material during assembly to create friction and mechanical interlocking that resists unthreading under vibration before any loosening can occur, preventing the problem rather than correcting it
4Reliability
If interference fit is used between coupling nut and connector body, then resistance to unthreading is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses material property changes (polymeric material with 70-90 Shore D durometer and glass fiber reinforcement) to achieve the interference fit effect, where material compliance and reinforcement compensate for manufacturing tolerances, reducing the need for high-precision machining while maintaining reliable connection
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 solution enhances the resistance to unthreading under vibration and thermal conditions, reduces material costs by using lightweight polymeric materials, and ensures secure assembly without the need for torque wrenches, while maintaining manufacturing tolerance flexibility.
Implementation Method 1
Incorporating a thread locking feature with an interference fit between the connector body and coupling nut
Data Source
AI summary
A coaxial connector includes a clamp nut dimensioned to fit over the outer conductor, the clamp nut having threads that mate with corresponding threads on the connector body. A clamp element is positioned between the clamp nut and a leading edge of the outer conductor. The connector body having an annular wedge surface dimensioned to mate with the leading edge of the outer conductor. The threads draw the clamp nut towards the connector body, to clamp the leading edge between the clamp element and the annular wedge surface. A surface-to-surface positive stop between the clamp nut and the connector body limits the compression force to a predetermined maximum by preventing further movement of the clamp nut towards the connector body. A thread lock is engaged as the positive stop is reached; the thread lock inhibiting unthreading of the clamp nut from the connector body.