Torque-Angle Fastening System Single-Operator Installation
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Solution Overview
Problem
Current fastening systems, particularly in structural applications, face challenges with labor-intensive installation, operator error, and variability in achieving consistent snug and final tensioning, often requiring multiple workers and equipment, which can lead to safety issues and costly errors due to over-tensioning and environmental dependencies.
Innovation Solution
A fastener system with a bolt and nut combination featuring a splined portion without a groove between the threaded and splined parts, allowing for single-sided, single-operator installation using a tool that applies both snugging torque and final tensioning through controlled nut rotation, ensuring consistent clamp load without torque reaction, and enabling easy removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional fastening systems are used with multiple workers and equipment, then installation can be performed, but labor costs and safety risks increase
Solution Approach 1:
The fastening system is segmented into distinct functional components: a fastener with splined portion for torque application, a reaction arm for providing counterforce, and a tool for controlled rotation. This segmentation allows each component to perform its specific function efficiently, enabling single-operator installation while maintaining installation quality
Solution Approach 2:
The reaction arm serves as an intermediary element that provides the necessary counterforce during fastener installation. It transfers the reaction force from the fastener to a stable surface, enabling the operator to apply torque without direct exposure to high forces, thus reducing safety risks while maintaining installation capability
2Manufacturing precision
If torque-based installation methods are used, then final tensioning can be achieved, but variability and repeatability issues arise
Solution Approach 1:
The system transitions from purely torque-based installation to a hybrid approach combining torque application with controlled rotation angle. By specifying both the torque value and the rotation angle (e.g., 90 degrees), the system achieves more consistent and repeatable tensioning results, reducing variability associated with torque-only methods
Solution Approach 2:
The controlled rotation mechanism provides inherent feedback by limiting the maximum rotation angle. This prevents over-tensioning by ensuring the fastener cannot rotate beyond the predetermined angle, thereby maintaining consistent tensioning across multiple installations and improving repeatability
3Ease of operation
If lubricants are applied to fasteners, then installation torque is reduced, but over-tensioning risk increases
Solution Approach 1:
The system applies lubricant in a controlled manner at predetermined locations on the fastener threads before installation. This preliminary action ensures consistent lubrication that reduces installation torque requirements while the controlled rotation mechanism subsequently prevents over-tensioning, maintaining both ease of operation and tension control accuracy
Solution Approach 2:
Lubricant application is localized to specific areas of the fastener threads rather than uniform application. This local quality approach ensures adequate lubrication for ease of installation while preventing excessive lubrication that could lead to over-tensioning, as the controlled rotation angle limits the total tension applied regardless of lubrication level
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 solution enables reliable, calibrated, and cost-effective single-operator installation with reduced operator error, improved safety, and consistent clamp load, reducing labor and equipment costs while minimizing environmental dependencies and the risk of over-tensioning.
Implementation Method 1
the tool provides both a desired snugging torque and a final tensioning to the fastener
Data Source
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AI summary
A fastening system that comprises a fastener and a single tool that provides both snugging torque and final tensioning to the fastener assembly, from a single side, with a single operator, with no torque feedback. The fastener comprises a nut (112) and a bolt (110) with a head (114) and a shank (116) extending axially from the head (114). The shank (116) has at least one threaded portion (118) and at least one splined portion (120), the splined portion (120) defming the end of the bolt (110). The splined portion (120)remains connected to the threaded portion (118) after fmal tensioning. The tool comprises a first socket (202) and a second socket (204), wherein the first socket (202) is engaged with an outer surface of the nut (112) and the second socket (204) is engaged with the splined portion (120) on the fastener. Snugging torque and final tension are both controlled by the tool.