Insulated Fastener With Segmented Head For Safety And Testing
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Solution Overview
Problem
Existing fasteners for terminating electrical conductors, such as those used in network interface devices, do not adequately prevent contact with metallic surfaces that can pose a safety hazard due to ringing voltages, despite the use of insulated screw heads, as determined individuals can still access and contact the screw head.
Innovation Solution
An insulated fastener with a metallic head featuring a counter bore and crenel portions forming a slot for tool access, where the insulating material covers the outer and top portions but leaves end faces and inner walls exposed to allow voltage sampling, and may include a guard base to prevent contact with washers and lugs, enhancing protection while allowing tool engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If insulated screw heads are used to prevent contact with metallic surfaces, then safety is improved, but determined individuals can still access and contact the screw head
Solution Approach 1:
The fastener is segmented into multiple functional zones: the head portion with driving recesses for tool engagement, the shaft portion for insertion, and the insulating material covering portions of the head and shaft. This segmentation allows different parts to serve different functions - tool access where needed and insulation where safety is critical.
Solution Approach 2:
The insulating material does not cover the entire fastener uniformly. Instead, it selectively covers the outer peripheral surface of the head portion and portions of the shaft, while leaving the driving recesses and inner walls exposed. This local application of insulation provides safety where contact hazard exists while maintaining tool accessibility where needed.
2Object-affected harmful factors
If insulating material covers the entire fastener, then safety is improved, but tool engagement becomes difficult
Solution Approach 1:
The insulating material is applied selectively to specific surfaces - covering the outer peripheral surface of the head portion and portions of the shaft, while deliberately leaving the driving recesses (slot, cross, or hexagonal recesses) exposed and accessible. This allows tool engagement through the recesses without interference from insulating material.
Solution Approach 2:
The fastener structure is divided into functional zones with different insulation characteristics. The head portion has insulating material on its outer surface but exposed driving recesses, while the shaft has selective insulation. This segmentation enables simultaneous achievement of safety and tool accessibility.
3Object-affected harmful factors
If insulating material covers all surfaces, then safety is improved, but voltage sampling becomes impossible
Solution Approach 1:
The insulating material coverage is designed with specific gaps and exposed metallic surfaces at strategic locations. The inner walls of the head portion and portions of the shaft remain metallic and exposed, allowing voltage sampling probes to contact these surfaces for testing while the insulating material prevents inadvertent contact with live components.
Solution Approach 2:
The insulating material acts as an intermediary that selectively permits or blocks contact. It blocks contact with hazardous metallic components while permitting controlled contact at exposed metallic surfaces for voltage sampling, thus mediating between safety requirements and testing needs.
4Ease of operation
If the screw head is fully exposed, then tool engagement is easy, but contact with metallic surfaces poses safety hazard
Solution Approach 1:
The head portion features insulating material on its outer peripheral surface to prevent contact hazards, while the driving recesses (slot, cross, or hexagonal) remain exposed for tool engagement. This local differentiation allows tool access without requiring full exposure of the head.
Solution Approach 2:
The head is segmented into an insulated outer surface and exposed driving recesses. This segmentation enables the outer surface to provide safety insulation while the recesses provide tool engagement interfaces, resolving the contradiction between protection and accessibility.
Data Source
AI summary
A metallic head of a fastener includes merlon portions between crenel portions. The crenel portions form a slot which may be used to tighten or loosen the fastener. An insulating material covers portions of the metallic head to prevent human contact with the metallic head and terminal lugs secured thereby. The metallic head defines a counter bore portion. Inner walls of the counter bore portion may be formed into a hexagon. The insulating material may extend into the counter bore portion covering the inner walls, as well as the surfaces of the crenel portions. The bottom of the counter bore may remain uncovered to facilitate signal testing with a test probe.