Blind Fastener Installation Tool for Flush Break-Off Control
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Solution Overview
Problem
Existing blind fasteners face challenges in controlling the rotation of both the bolt and nut during installation, ensuring a flush finish, adapting to variations in grip length, and preventing tulip configuration due to excessive torque, while also requiring post-installation grinding for aesthetics and aerodynamics.
Innovation Solution
A tool for installing a blind fastener comprising a base, collet, socket assembly, drive body, and mode clutch, which includes rollers to engage the bolt and a mechanism to control the rotation of the nut and bolt, allowing for controlled torque application and flush installation without additional machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a typical blind fastener is installed by rotating the core bolt to provide preload, then the fastener can be installed from one side, but the break-off point of the core bolt cannot be controlled and post-installation grinding is required
Solution Approach 1:
The fastener is divided into two separate pieces: a nut with an internally threaded sleeve and a bolt with externally threaded shaft. This segmentation allows the nut to remain in the workpiece while the bolt is rotated and then broken off at a controlled location, eliminating the need for post-installation grinding.
Solution Approach 2:
A tool is introduced as an intermediary device to control the rotation of both the bolt and nut during installation. The tool includes a socket assembly that engages the bolt and a collet that engages the nut, allowing precise control of the breaking process to achieve a flush finish.
2Strength
If excessive torque is applied to the fastener during installation, then the fastener can be tightened to provide preload, but the sleeve may flare out to form a tulip configuration resulting in defective installation
Solution Approach 1:
The tool incorporates a mode clutch mechanism that provides feedback control during the installation process. The clutch disengages when the bolt breaks off, automatically preventing excessive torque application that would cause the sleeve to flare out and form a defective tulip configuration.
3Adaptability or versatility
If the blind fastener needs to adapt to variations in grip length, then the fastener can accommodate different panel thicknesses, but maintaining joint strength becomes more difficult
Solution Approach 1:
The fastener design allows the bolt shaft to be rotated and broken off at different positions depending on the grip length required. This dynamic adjustment capability enables the same fastener type to accommodate various panel thicknesses while maintaining adequate joint strength by optimizing the exposed bolt length.
4Manufacturing precision
If rotation of both the bolt and nut is controlled during installation, then a flush finished product can be achieved, but the complexity of the installation tool increases
Solution Approach 1:
The installation tool combines multiple functions into a single integrated device: the socket assembly engages the bolt for rotation, the collet engages the nut for control, and the mode clutch automatically manages the breaking process. This merging of functions achieves flush finish control without requiring multiple separate tools or complex manual operations.
Data Source
AI summary
A tool for installing a blind fastener including a bolt and a nut includes a collet, a socket assembly, a drive body and a mode clutch. The collet is configured to selectively engage a tool engagement portion of the nut. The socket assembly includes a socket housing and a plurality of rollers. The socket housing defines a bore disposed about the axis. A surface of each roller is configured to engage a cylindrical tool engagement portion of the bolt within a bore to rotate the bolt about an axis. The drive body is coupled to the socket housing and configured to rotate the socket housing about the axis. The mode clutch is operable in an engaged mode in which the socket housing is coupled to the collet for common rotation about the axis and a disengaged mode in which the socket housing is rotatable relative to the collet.