Inner Ferrule Gripping Structure for Coaxial Cable Retention
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Solution Overview
Problem
Existing electrical terminals with smooth inner ferrules lack sufficient axial retention force to securely attach to coaxial cables, and complex manufacturing processes are required for folded inner ferrule designs.
Innovation Solution
A cylindrical inner ferrule with a first and second portion separated by a seam, featuring gripping features on its inner surface to deform the dielectric layer of the coaxial cable, combined with a cylindrical outer ferrule for enhanced retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inner ferrule has a smooth inner surface, then the manufacturing process is simple, but the axial retention force to the coaxial cable is insufficient
Solution Approach 1:
The inner ferrule transitions from a uniformly smooth surface to having localized gripping features (knurling, ridges, or grooves) on its inner surface. These localized features concentrate deformation force on specific areas of the dielectric layer, creating mechanical interlocking without requiring complex manufacturing processes for the entire ferrule structure.
Solution Approach 2:
The inner ferrule surface geometry is modified by adding gripping features that change the physical parameters of the interface between the ferrule and dielectric layer. This includes creating surface irregularities that increase friction and mechanical engagement, thereby increasing axial retention force while maintaining manufacturing simplicity.
2Force
If the inner ferrule is folded under the shield conductor to increase axial retention force, then the retention force increases, but the manufacturing process becomes more complicated
Solution Approach 1:
Instead of folding the entire inner ferrule structure under the shield conductor, the invention applies gripping features only to the inner surface of the ferrule that contacts the dielectric layer. This localized modification achieves enhanced retention without requiring complex folding operations or additional structural complexity.
Solution Approach 2:
The invention extracts the retention function from the overall ferrule structure and concentrates it in the gripping features on the inner surface. This separates the retention function from the structural function, allowing the ferrule to maintain its simple cylindrical form while achieving enhanced retention through surface features alone.
3Force
If gripping features are added to the inner surface of the inner ferrule, then the axial retention force increases, but the manufacturing precision requirements increase
Solution Approach 1:
The gripping features are designed as discrete, segmented elements (such as individual knurls, ridges, or grooves) rather than continuous complex patterns. This segmentation allows each feature to be formed independently using standard manufacturing processes, reducing the overall precision requirements compared to continuous complex surface profiles.
Solution Approach 2:
The gripping features utilize material deformation properties of the sheet metal preform during forming. By controlling the deformation process parameters (such as roll pressure and geometry), the gripping features can be created with adequate precision using conventional manufacturing methods, without requiring ultra-precision machining or assembly operations.
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 gripping features on the inner ferrule increase the axial retention force by deforming the dielectric layer, providing a secure attachment to the coaxial cable without the need for complex manufacturing processes.
Implementation Method 1
the inner ferrule and the shield conductor of the coaxial cable surrounding the inner ferrule in order to increase the axial retention force of the inner ferrule to the coaxial cable
Implementation Method 2
deforming the cylindrical dielectric layer using the gripping features as the seam is closed
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
An electrical terminal (200) includes a cylindrical inner ferrule (208) having a first portion (212) and a second portion (214) separated by at least one seam (216) therebetween. An inner surface of the first portion (212) and/or second portion (214) defines a gripping feature (220) that is configured to deform a cylindrical dielectric layer (222) surrounding an electrical conductor (224) of an electrical cable. The electrical terminal (200) also includes a cylindrical outer ferrule (210) surrounding the inner ferrule (208). A method (300) of assembling an electrical cable is also presented.