Self-Drilling Fastener Geometry for Drill Time and Pullout Force
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Solution Overview
Problem
There is a need for self-drilling self-tapping fasteners that improve drilling time and pullout force without compromising ductility, tapping torque, torsional strength, or tensile strength.
Innovation Solution
The self-drilling self-tapping fastener features a head, shank, and helical thread formation with a drill tip and flutes, including chip breakers, formed from low carbon steel with a hardened surface for improved drilling and tapping capabilities, maintaining ductility and strength through specific design and manufacturing processes like forging and milling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fastener uses conventional drilling and tapping operations, then the process is simple, but the drilling time is excessive and pullout force is insufficient
Solution Approach 1:
The patent combines drilling and tapping operations into a single self-drilling self-tapping fastener that performs both functions simultaneously. The fastener features a drill tip for drilling and helical thread formation for tapping, eliminating the need for separate operations and significantly reducing drilling time while improving pullout force through integrated thread engagement.
Solution Approach 2:
The fastener is designed to perform drilling and tapping operations autonomously without requiring separate tools or operations. The self-drilling self-tapping mechanism allows the fastener to create its own hole and form threads simultaneously, reducing process complexity and time while maintaining structural integrity and pullout strength.
2Strength
If the fastener uses hardened surface treatment, then drilling and tapping capabilities are improved, but ductility may be compromised
Solution Approach 1:
The fastener applies hardened surface treatment selectively to specific areas that require enhanced drilling and tapping capabilities, while maintaining the base material's ductility in other regions. This localized hardening approach allows the surface to resist wear and deformation during operation while the core material retains its formability and toughness.
Solution Approach 2:
The fastener utilizes a composite structure combining a ductile base material with a hardened surface layer. This composite approach allows the core material to provide formability and toughness while the hardened surface provides enhanced drilling and tapping capabilities, resolving the contradiction between strength and ductility.
3Force
If the fastener increases thread engagement for higher pullout force, then pullout force improves, but drilling torque requirements increase
Solution Approach 1:
The fastener employs dynamic thread formation that adapts to the drilling process. The helical thread formation is designed to progressively engage the material as the fastener advances, optimizing the balance between pullout force and drilling torque. The thread geometry and engagement depth are dynamically adjusted during the self-drilling self-tapping process to minimize energy requirements while maximizing pullout strength.
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 results in a faster drilling time and higher pullout force while maintaining or improving other performance metrics like ductility, tapping torque, and tensile strength compared to commercially available fasteners.
Implementation Method 1
The drill tip includes a first cutting blade having a first cutting edge and a second cutting blade having a second cutting edge. The first cutting edge and the second cutting edge are tapered toward each other.
Implementation Method 2
formed from low carbon steel with a hardened surface for improved drilling and tapping capabilities
Implementation Method 3
a helical thread formation outwardly extending from the shank for frictionally engaging the objects into which the fastener is driven
Implementation Method 4
The second shank portion defines a longitudinally extending first flute and a longitudinally extending second flute. The second shank portion includes a first chip breaker positioned in the first flute and a second chip breaker positioned in the second flute.
Data Source
AI summary
A self-drilling self-tapping fastener that provides improved performance in both drilling time and pullout force without decreasing performance in any of ductility, tapping torque, torsional strength, and tension strength.