Off-Center Perforation Tab for Standing-Seam Tray Torque Management
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Solution Overview
Problem
Existing fixed legs for zinc or zinc alloy trays in standing seam roofing systems face issues with deformation and insufficient resistance due to the use of small diameter nails or screws, which can wind and cause installation difficulties, leading to poor crimping and aesthetics, and the transition to a single large diameter screw results in torque-induced deformation of the bracket and tray.
Innovation Solution
A metal fixing lug with a single off-center perforation for a screw, designed to reduce torque transmission and deformation, featuring a hook and stop configuration that offsets the screw's force, combined with reinforcements and a casing for reduced friction, allowing for a 5 or 6 mm screw installation without deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If small diameter ringed nails or screws (up to 4 mm) are used to fix the bracket to the support, then the bracket can be installed on wooden or derivative supports, but the nails or screws can wind up due to drying cycles of the wood and repetitive stresses of the wind, causing insufficient resistance to tearing
Solution Approach 1:
The invention changes the critical parameter of screw diameter from small (4mm) to large (12mm), fundamentally altering the mechanical properties of the fixation system. The larger diameter provides significantly higher resistance to tearing and wind uplift forces, while the specific geometric design of the bracket body compensates for the increased torque to prevent deformation.
Solution Approach 2:
The bracket body features an asymmetric geometry with a specific shape that is optimized to distribute the high torque generated by the large diameter screw. The asymmetric design allows the bracket to better engage with both the tray and support, providing enhanced stability and resistance to rotational forces that would cause winding or deformation.
2Productivity
If a single large diameter screw is used to fix the bracket, then installation is simpler and faster, but the torque transmitted to the bracket during tightening can deform the bracket or the tray
Solution Approach 1:
The asymmetric geometry of the bracket body is specifically designed to manage and distribute the high torque generated by the large diameter screw. The shape provides natural stress distribution paths that prevent concentration of forces at critical points, thereby avoiding deformation of the bracket or tray during tightening while maintaining installation simplicity.
Solution Approach 2:
The bracket incorporates local geometric features and reinforcements in specific areas to handle the high stress concentrations that occur during screw tightening. The local quality of the bracket material and shape is optimized at critical zones to resist deformation while maintaining overall simplicity for fast installation.
3Reliability
If multiple holes with casing are provided in the bracket, then the fixation can be more secure, but the device complexity increases and installation time increases
Solution Approach 1:
The invention extracts and eliminates the unnecessary complexity of multiple holes and casings, retaining only the essential single large diameter screw fixation. The simplified design achieves adequate or superior fixation security through the optimized bracket geometry and larger screw diameter, removing redundant components that increase complexity and installation time.
Solution Approach 2:
The bracket is designed as a single integrated piece with optimized geometry rather than multiple separate components. This segmentation into a unified structure with built-in stress distribution features achieves secure fixation without requiring multiple holes or separate casing elements, thereby reducing device complexity and installation time.
Data Source
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AI summary
In roof covering systems using zinc or zinc-alloy trays with standing-seam crimping, the use of tabs secured by two screws is well known. The invention particularly relates to a metal fastening tab for securing a standing-seam tray on a wood or wood-derivative carrier, which comprises a first surface (1) with a perforation (2) for receiving a screw for attachment onto the carrier, a second surface (3) generally perpendicular to said first surface and including a hook (4) for engaging with the ridge of the tray to be secured, the two surfaces defining an edge (5), characterised in that the first surface includes a single perforation (2) for receiving a single screw, and in that the centre (6) of said perforation (2) is not included in the mediator (7) of the edge (5) in order to reduce the force applied on the tab and on the tray by the torque induced when tightening said screw. Such a tab, with a single large-diameter screw, is easier and quicker to place than traditional tabs. The tab is specially designed to limit its own torsion and to avoid any buckling of the tray to be secured when tightening the single screw.