Interlocking Threaded Fastener Profile for Shear-Resistant Sealing
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Solution Overview
Problem
Existing threaded fasteners, particularly those with dovetail geometry, face challenges in providing sufficient resistance to vertical shear, bending moments, and axial translation while maintaining a secure interlocking grip and sealing ability, especially in thin-walled castings and applications requiring vertical loading.
Innovation Solution
A new thread design featuring a spiraling thread with 'V' angles and a dovetail cross-section, providing an interlocking 'double hook' contact surface that resists spreading forces and enhances vertical loading capabilities, along with the ability to form a gas-tight seal, using conventional thread rolling processes for cost-effective manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional threaded fasteners with dovetail geometry are used, then the fastener provides basic holding properties through friction, but it lacks sufficient resistance to vertical shear, bending moments, and axial translation
Solution Approach 1:
The thread profile is segmented into distinct functional zones: upper flanks for vertical loading, lower flanks for radial clamping, and crest/root regions for sealing. This segmentation allows each portion of the thread to specialize in resisting specific forces, thereby simultaneously improving strength and reliability.
Solution Approach 2:
The thread profile employs asymmetric geometry with different flank angles and curvatures optimized for different force directions. The upper flanks are configured to resist vertical shear and bending, while lower flanks provide radial clamping, creating an asymmetric structure that enhances multi-directional strength without compromising sealing reliability.
2Strength
If the thread profile is made more complex to improve strength and sealing, then resistance to axial translation and vertical shear increases, but manufacturing difficulty and cost increase
Solution Approach 1:
The complex thread profile is achieved by modifying geometric parameters (flank angles, curvatures, pitch) of a conventional thread form rather than introducing fundamentally new manufacturing processes. This allows advanced strength characteristics to be obtained through parameter optimization while maintaining compatibility with existing thread rolling equipment.
Solution Approach 2:
The patent replaces complex multi-step machining operations with a single-pass thread rolling process. The sophisticated thread profile is formed plastically during rolling, substituting mechanical cutting with forming operations that are both simpler and more cost-effective despite the profile complexity.
3Strength
If the thread design is optimized for vertical loading, then resistance to axial translation improves, but the fastener becomes more difficult to manufacture cost-effectively
Solution Approach 1:
The patent replaces complex machining operations required to create vertically optimized thread profiles with a single-pass thread rolling process. This substitution of forming for cutting enables cost-effective production of vertically loaded fasteners by eliminating multiple setup and tooling changes.
Solution Approach 2:
The thread profile is designed to perform multiple functions simultaneously: vertical load resistance through upper flank geometry, radial clamping through lower flank geometry, and sealing through crest/root configuration. This multi-functionality is achieved within a single manufacturing pass, improving productivity while maintaining enhanced vertical loading capability.
Data Source
AI summary
An interlocking thread with a tooth-cross-section that is wider at its crest than at its root and with “V” angles located both along the crest and the root which tightens into a tapped hole that has a similar thread cross-section.