Dual-Zone Fastener Socket Geometry for Cam-Out Resistance
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Solution Overview
Problem
Existing fasteners and drivers experience premature cam-out and breakage due to poor fit caused by anti-corrosive coatings and localized stress concentrations, which reduce surface contact and increase the risk of deformation.
Innovation Solution
A fastener design featuring a dual zone socket area with an upper inwardly tapering section and a lower vertical section, along with a corresponding driver bit, providing enhanced engagement through asymmetrical driving and removal surfaces, allowing for increased surface contact and torque distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anti-corrosive coatings are applied to the fastener, then corrosion resistance is improved, but surface contact area is reduced leading to premature cam-out
Solution Approach 1:
The socket is designed with a dual-zone structure: an upper zone with reduced diameter (accommodating the coating thickness) and a lower zone with full diameter (providing full surface contact). This local differentiation allows the fastener to maintain both corrosion resistance from the coating and full surface contact for torque transmission.
2Area of stationary object
If the driver and recess are designed to fit closely for maximum face-to-face contact, then surface contact is improved, but clearance for insertion is reduced
Solution Approach 1:
The socket is segmented into two distinct zones along its length: an upper portion with a first diameter and a lower portion with a second diameter. This segmentation allows the driver to be inserted easily through the upper zone while achieving maximum contact in the lower zone.
3Force
If torque is applied through localized stress regions, then driver-to-fastener force transmission is achieved, but deformation and breakage occur
Solution Approach 1:
The socket geometry creates different functional zones: the upper zone with reduced diameter facilitates driver insertion and positioning, while the lower zone with full diameter provides extensive surface area for distributing torque forces, preventing localized stress concentrations that lead to deformation and breakage.
Data Source
AI summary
Methods and apparatus for a fastener head having a dual zone socket area and a mating driver bit according to aspects of the present technology include a fastener configured with driving surfaces adapted to provide enhanced engagement between each other during use. The fastener includes a recessed socket area with a sidewall that has an upper inwardly tapering section and a lower vertical section that extends to the bottom of the recessed socket area. The upper inwardly tapering section of the sidewall may also include an offset relative to the lower vertical section to create asymmetrical driving and removal surfaces. The technology also includes a corresponding mating driver bit configured with mating surfaces to the fastener to provide enhanced engagement between the fastener and mating driver bit. The technology also allows either the fastener or the driving bit to be used with preexisting fasteners and driver bits.