Nut Restraining and Centering for One-Sided High-Strength Bolting
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Solution Overview
Problem
Current methods for installing high-strength bolted connections from one side often result in reduced load-carrying capacity, increased costs, and compromised installation tolerances, making them inefficient and costly for construction applications.
Innovation Solution
A nut restrainer system comprising a cup-shaped nut holder with a regular hexagonal profile and centering protrusions that allows for the insertion and securement of a nut over a bolt hole from one side, enabling the installation of high-strength bolts without sacrificing load-carrying capacity or installation tolerances, and a centering tool for precise alignment and immobilization during installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If high-strength bolted connections are installed from one side only, then installation accessibility is improved, but installation tolerances are compromised
Solution Approach 1:
The patent introduces a nut restrainer as an intermediary device that is temporarily installed on the accessible side of the substrate plate. This restrainer holds the nut in precise alignment with the bolt hole, acting as a mediator that enables one-sided installation while maintaining the precision normally achieved through two-sided access. The restrainer includes positioning features that ensure the nut remains coaxial with the bolt hole throughout the tightening process.
Solution Approach 2:
The nut restrainer is installed preliminarily before the actual bolt tightening operation. By pre-positioning the nut within the restrainer on the accessible side, the system prepares the connection in advance, allowing the bolt to be inserted and tightened from one side without compromising alignment. This preliminary positioning action eliminates the need for precise manual alignment during the tightening process.
2Ease of operation
If blind bolts are used for one-sided installation, then installation accessibility is improved, but load-carrying capacity is reduced
Solution Approach 1:
Instead of modifying the bolt to enable one-sided installation (as with blind bolts), the patent inverts the approach by restraining the nut on the accessible side. This allows the use of standard high-strength bolts and nuts that maintain full load-carrying capacity, while the restrainer provides the one-sided installation capability. The solution turns the conventional wisdom around by showing that the nut, not the bolt, should be the element restrained.
3Ease of operation
If welding is used to attach the nut to the substrate, then installation accessibility is improved, but code compliance and installation tolerances are compromised
Solution Approach 1:
The nut restrainer serves as a temporary intermediary device that enables one-sided installation without permanently modifying the nut or substrate through welding. The restrainer is installed, the nut is positioned within it, and then the restrainer is removed after the bolt is tightened. This approach maintains code compliance by avoiding welded nuts while still achieving the accessibility benefits of one-sided installation.
Data Source
AI summary
In accordance with one or more embodiments of the invention, nut restrainers, centering tools, and methods of use are presented, particularly as applied to high strength bolted connections. Nut restrainers may have an interior profile including a circular profile section and a regular hexagonal profile section, a nut inserted into the nut restrainer may have lateral freedom of movement, and the nut restrainer may have a top plane with one or more centering protrusions. A centering tool for positioning a nut restrainer may have a non-circular head section, a cylindrical positioning section, a threaded section, and a cylindrical restrainer positioning section; a method of positioning a nut restrainer coaxial with a bolt hole using the centering tool.