Enlarged Head Fastener with Convergent Transition for Pull-Through Resistance
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Solution Overview
Problem
Conventional fasteners, such as nails and screws, face challenges in pull-through resistance, particularly in thick substrates, and often damage the wood substrate due to their design, leading to structural integrity issues during high wind or seismic events.
Innovation Solution
An enlarged head fastener design with a convergent transition portion and ridge formations that provides enhanced pull-through resistance by distributing the force more evenly and resisting deformation, while being manufactured using a specialized die assembly process that forms the head and shank in a single impact, reducing manufacturing costs and improving retention capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional fasteners with small heads are used, then the fastener can be easily driven into the substrate, but the pull-through resistance is insufficient especially in thick substrates
Solution Approach 1:
The patent transitions from conventional small-headed fasteners to an enlarged head design where the head diameter is significantly larger than the shank diameter. This dimensional change in the head size provides increased pull-through resistance by distributing loads over a larger bearing surface area, while the convergent transition portion enables the fastener to still be driven effectively into the substrate.
Solution Approach 2:
The patent modifies geometric parameters of the fastener, specifically the head diameter, transition portion angle, and head thickness. These parameter changes optimize the balance between ease of driving (controlled by transition portion geometry) and pull-through resistance (controlled by head size and bearing surface area).
2Force
If the head size is enlarged to increase pull-through resistance, then the bearing surface area increases, but the fastener may cause more deformation or damage to the substrate material
Solution Approach 1:
The patent applies local quality by creating a convergent transition portion that gradually transitions from the shank to the enlarged head. This gradual transition distributes the deformation zone along the transition portion rather than concentrating it at a single point, thereby reducing localized fiber rupture while still achieving the enlarged bearing surface area needed for pull-through resistance.
Solution Approach 2:
The patent employs curved and rounded geometric features in the head design, including a rounded head periphery and a convergent transition portion with gradual curvature. These curved features distribute stresses more evenly compared to sharp edges, reducing the likelihood of substrate fiber rupture while maintaining structural integrity.
3Force
If an enlarged head design is implemented, then pull-through resistance improves, but the manufacturing complexity increases
Solution Approach 1:
The patent merges the head formation and shank formation into a single integrated die set and single hammering operation. The opposing dies are configured with integrated cavities that form both the enlarged head and the shank simultaneously in one impact, eliminating the need for separate forming operations and reducing manufacturing complexity despite the complex geometry.
Solution Approach 2:
The patent optimizes the geometric parameters of the transition portion, specifically controlling the angle and gradual curvature, to enable forming in a single hammering operation. This parameter optimization allows the complex enlarged head geometry to be manufactured efficiently using conventional single-impact hammering processes without requiring multiple operations or specialized equipment.
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 enlarged head fastener demonstrates superior pull-through resistance compared to traditional fasteners, with increased resistance proportional to substrate thickness, and reduced deformation, enhancing structural integrity without compromising the substrate material.
Implementation Method 1
hammering the end of the metal wire protruding from the first die ends in a single impact and forcing material from the metal wire to flow out into and fill the head forming cavity and the convergent transition portion forming cavity
Data Source
AI summary
An enlarged head fastener device and method for manufacturing the same is described. The enlarged head fastener device includes a shank and a head. The head extends outwardly from the shank in a transverse plane to define a head periphery. The head has an anterior side and a posterior side. The anterior side includes a bearing surface and a convergent transition portion that reinforces the head. The convergent transition portion extends between a large end adjacent the bearing surface to a small end adjacent the shank. At least one ridge formation projects from the anterior side of the head providing additional reinforcement. The ridge formation extends continuously between an outboard end positioned on the anterior side of the head adjacent the head periphery and an inboard end positioned on the shank. The head may be centered or offset relative to the shank.