Threaded Fastener Protrusions Prevent Backout
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Solution Overview
Problem
Existing threaded fasteners often loosen due to low clamping torque, especially in thin metal and wood applications, leading to joint failures as the difference between drive torque and strip torque is small, causing fastener backout.
Innovation Solution
The fastener design features a helical thread with protrusions extending from the crest and flank portions, providing increased tapping and clamping torque through frictional engagement with the material, and featuring a pointed peak that extends to the root of the thread, which compresses the material to enhance back-out torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional threaded fasteners are used in thin metal materials, then installation is simple, but the difference between drive torque and strip torque is very small resulting in low clamping force
Solution Approach 1:
The thread structure is segmented into multiple functional zones: standard thread portions for engagement and protrusion portions extending from the crest toward the root. These protrusions create additional friction surfaces and material compression zones that increase clamping force without requiring complete redesign of the fastener geometry
Solution Approach 2:
The protrusions are strategically positioned at specific locations along the thread length where maximum clamping force is needed. The protrusion height and angle are locally optimized to create sufficient friction and compression in thin metal materials while maintaining compatibility with standard thread engagement zones
2Reliability
If conventional threaded fasteners are used in wood, then installation is straightforward, but wood fibers shrink and lose ability to hold thread engagement securely causing fastener backout
Solution Approach 1:
The protrusions are designed to preemptively counteract the loosening force by creating continuous frictional resistance and material compression along the thread engagement path. This preliminary anti-action prevents the fastener from backing out even when wood fibers shrink and lose engagement security
Solution Approach 2:
The protrusions convert the potentially harmful effect of wood fiber shrinkage into a beneficial compression force. As wood fibers shrink, they compress against the protrusions, which in turn compress the material between thread flanks, increasing friction and preventing backout rather than causing loosening
3Force
If protrusions are added to increase clamping torque, then tapping torque and clamping torque increase through friction, but thread structure becomes more complex
Solution Approach 1:
The thread is divided into standard engagement portions and protrusion portions. The protrusions are segmented features that extend from the crest toward the root at specific intervals, creating friction surfaces without requiring complete geometric redesign of the entire thread structure
Solution Approach 2:
The protrusion geometry parameters (height, angle, spacing) are optimized to achieve sufficient friction and compression effects. The protrusion height is typically 10-50% of the thread depth, and the angles are designed to create effective material compression while maintaining manufacturability with standard threading processes
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 design significantly increases the clamping and back-out torque, preventing fastener loosening by compressing the material between the thread flank portions, thereby enhancing the stability and performance of the fastened joint.
Implementation Method 1
tapping torque and clamping torque is generated by friction from the flank portion and root of the thread contacting the thin metal
Implementation Method 2
The pointed peak that extends to the root of the thread, which compresses the material to enhance back-out torque
Data Source
Figure 1~4
Figure 5~7
Figure 8~9
AI summary
A fastener is provided including an elongated body having a first end (1) and a second end (12), and a helical thread (20) formed on at least a portion of the elongated body where the thread has a crest (22), a root (25), and flank portions (28). The helical thread has at least one protrusion (50) extending from the crest and flank portions toward the first end of the elongated body, and each protrusion has a peak (52) that extends to the root of the thread.