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
1Area of stationary object
If the driver and recess are designed to fit closely for maximum face-to-face contact, then surface contact area is improved, but clearance is reduced making insertion difficult
Solution Approach 1:
The recessed socket area is segmented into two distinct zones: an upper zone with greater cross-sectional area and a lower zone with smaller cross-sectional area. This segmentation allows the driver to be inserted through the upper zone with adequate clearance while achieving maximum contact area in the lower zone where the fastening force is applied.
Solution Approach 2:
Different zones of the recessed socket area are given different geometric properties. The upper zone has a larger cross-sectional area to facilitate easy insertion and removal of the driver, while the lower zone has a smaller cross-sectional area optimized for maximum surface contact and torque transmission during fastening operations.
2Reliability
If anti-corrosive coatings are applied to the fastener, then corrosion resistance is improved, but the depth of driver extension into the recess is reduced causing premature cam-out
Solution Approach 1:
The recessed socket area is pre-configured with a dual zone geometry that anticipates the presence of anti-corrosive coatings. The upper zone provides additional depth compensation that accounts for the coating thickness, ensuring that the driver can extend sufficiently into the lower zone to achieve full contact area even when coatings are present.
3Force
If torque is applied through localized stress regions, then fastening function is achieved, but deformation and breakage occur
Solution Approach 1:
The lower zone of the recessed socket area serves multiple functions simultaneously: it provides the primary torque transmission surface, distributes stress across a larger contact area to prevent localized deformation, and maintains structural integrity during both installation and removal operations. This multi-functional design eliminates the need for separate stress distribution features.
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.