Threaded Fastener Shank Design for Higher Torsional Strength
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Solution Overview
Problem
Threaded fasteners often fail due to significant torsional stresses when driven into substrates like concrete, causing the shank to break, particularly because existing designs allocate material inefficiently between the head, shank, and thread formations, leading to inadequate strength and increased frictional resistance.
Innovation Solution
A threaded fastener design with a shank comprising multiple portions, where the first helical thread formation extends along the second and third portions, and a second helical thread formation is limited to the section adjacent to the tip, allowing for larger shank diameters and increased strength by reallocating material from thread formations to the shank, thereby reducing torsional stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If shank diameter is increased, then torsional strength is improved, but material available for thread formations is reduced
Solution Approach 1:
Instead of providing thread formations along the entire length of the shank, the second helical thread formation is provided only in the section of the third portion adjacent to the tip. This partial action approach uses less material for thread formations, allowing more material to be allocated to increasing the shank diameter and improving overall torsional strength, while still providing adequate thread engagement in the critical gripping section near the tip.
2Ease of operation
If frictional resistance is reduced, then driving into substrate is easier, but thread gripping capability may be compromised
Solution Approach 1:
The patent employs two different helical thread formations with potentially different parameters (pitch, depth, angle) to optimize both driving ease and gripping capability. The first helical thread formation provides steady engagement during driving, while the second helical thread formation in the tip section provides enhanced gripping. This parameter differentiation allows the fastener to be driven easily while maintaining strong grip in the substrate.
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 enhances the torsional strength of the shank, reducing the likelihood of failure and improving the fastener's ability to securely engage substrates without compromising the head and thread functionality.
Implementation Method 1
the threads of the thread formation(s) of the threaded fastener grip the inside surfaces of the substrate that define the cavity
Implementation Method 2
a first helical thread formation extending outwardly from the second and third portions of the shank; a second helical thread formation extending outwardly from a section of the third portion of the shank
Data Source
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AI summary
A threaded fastener including a head, a shank connected to the head at a first end of the shank, the shank includes a first portion, a second portion, a third portion, and a tip at an end of the shank opposite the head. The fastener includes a first helical thread formation extending outwardly from the second and third portions of the shank, and a second helical thread formation extending outwardly from a section of the third portion of the shank that is adjacent to the tip. The first helical thread formation defines grooves in the section of the third portion of the shank that is adjacent to the tip.