Plastic Expansion Nail With Stiffening Guide Ribs
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Solution Overview
Problem
Previous fastening means with plastic expanding nails tend to break at the transition from the cylindrical nail shank to the threaded expanding section due to high driving force requirements, leading to reduced strength and increased susceptibility to breakage, and are not suitable for push-through assembly or insulation panels.
Innovation Solution
The plastic expanding nail features diametrically opposed stiffening guide ribs that run continuously from the nail head to the tip, engaging with longitudinal slots in the dowel sleeve, which provides additional strength and reduces the risk of breakage, while the dowel sleeve maintains a uniform diameter and includes a holding plate for enhanced support and assembly precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the plastic expanding nail is made with high glass fiber content to achieve high rigidity, then the nail becomes stiffer, but the susceptibility to breakage increases
Solution Approach 1:
The patent uses plastic material with high glass fiber content (at least 20% by weight, preferably 30-50%) to create a composite material that achieves the necessary rigidity while maintaining acceptable breakage resistance. The glass fibers reinforce the plastic matrix, providing the structural strength needed for the expanding nail to function properly without breaking during installation or under load.
2Reliability
If the spreading pressure is reduced to prevent nail breakage, then the risk of breakage decreases, but the pull-out holding forces become unacceptable
Solution Approach 1:
The patent applies local quality by creating different structural characteristics in different zones of the expanding nail. The front end features a thread-like expansion section with controlled spreading pressure for reliable anchoring, while the rear end has a ribbed construction for engagement with the hollow shank. This zonal differentiation allows the nail to achieve both low breakage risk and high holding force.
Solution Approach 2:
The thread-like expansion section at the front end of the nail features a curved, helical geometry that distributes the spreading pressure more evenly around the hollow shank. This curved thread structure reduces stress concentrations compared to straight radial expansion, thereby lowering the risk of breakage while maintaining effective anchoring.
3Ease of operation
If the hollow shank of the dowel sleeve has a significantly larger external dimension than the pre-drilled hole, then the ribbed construction can interact with the hollow shaft, but the fastening means is not suitable for push-through assembly
Solution Approach 1:
The patent segments the dowel sleeve into distinct functional zones: a hollow shank portion for receiving the expanding nail, an expansion zone with controlled thickness for radial expansion during installation, and a front end portion that provides the necessary external dimensions for push-through assembly. This segmentation allows each zone to optimize its function while working together as a complete system.
Solution Approach 2:
The dowel sleeve is designed with dynamic characteristics that allow it to transition from a rigid structural component to a flexible expansion element during installation. The controlled thickness in the expansion zone enables the sleeve to deform radially outward when the expanding nail is driven in, facilitating push-through assembly while maintaining structural integrity.
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
This design significantly reduces the risk of breakage and enhances the strength of the fastening means, allowing for safer and more effective attachment of components like insulation panels without compromising on pull-out holding forces.
Implementation Method 1
the front end in the direction of assembly has a radially widening, thread-like expansion section, with the dowel sleeve being introduced into a pre-drilled hole through the component down to the subsurface and being anchored in the subsurface by driving in the plastic expanding nail
Data Source
Figure 1~2
Figure 3~5
Figure 4
AI summary
The invention relates to a fastening device for attaching components, such as insulation boards and similar insulating materials or wooden substructures, to a load-bearing substrate, comprising a dowel sleeve (9; 11) formed with an expansion zone (14) and a plastic expansion nail (1) which has guide ribs (2a, 2b) extending in the mounting direction (5) and at its front end in the mounting direction (5) a thread-like expansion section (6) which radially expands the expansion zone (14) of the dowel sleeve (9; 11) when driven in. Such a fastening device with reduced risk of breakage and improved strength values is characterized according to the invention in that the plastic expansion nail (1) is formed with at least two stiffening guide ribs (2a, 2b) arranged diametrically opposite each other, which extend continuously from below the nail head (3) over the expansion section (6) to the nail tip (4), wherein the stiffening guide ribs (2a;2b) have a width measured from the outer edge of one rib (2a) to the outer edge of the other rib (2b) which corresponds approximately to the outer diameter of the dowel sleeve (9; 11) but is not larger than the diameter of the pre-drilled hole (17) and wherein the dowel sleeve (9; 11) has a longitudinal slot (13a, 13b) extending from below the dowel head (10) to the dowel tip (12) on at least two opposite sides for receiving the stiffening guide ribs (2a, 2b).