Blind Fastener Installation Tool With Switchable Nut Rotation 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 maintaining joint strength and reducing installation costs.
Innovation Solution
A tool for installing a blind fastener that includes a driving member, collet, nosepiece, retaining sleeve, and follower, which inhibits nut rotation and controls torque, featuring a cam mechanism to move the follower radially inward against the nut, and uses ejector pins and springs to secure the bolt and nut components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the core bolt is rotated to provide preload after sleeve deformation, then the panels can be clamped together, but the break-off point cannot be controlled and post-installation grinding is needed
Solution Approach 1:
The patent incorporates a controlled break-off feature directly into the core bolt design, where a frangible portion is pre-positioned to break at a specific point that ensures the bolt end is flush with the panel surface. This preliminary design feature eliminates the need for post-installation grinding while maintaining joint strength.
2Manufacturing precision
If rotation of both bolt and nut is controlled during installation, then proper preload can be achieved, but installation complexity increases
Solution Approach 1:
The patent separates the rotation control functions into distinct components: the core bolt is designed to rotate freely to achieve preload, while the nut has a controlled break-off feature that prevents over-rotation. This segmentation allows each component to perform its specific rotational function independently, simplifying the overall installation process while maintaining precision.
3Strength
If excessive torque is applied to the fastener, then preload can be increased, but the sleeve flares out to form tulip configuration
Solution Approach 1:
The patent incorporates a torque control feature in the form of a controlled break-off portion on the core bolt that prevents excessive torque application. When the predetermined torque is reached, the frangible portion breaks, automatically limiting the torque and preventing the sleeve from flaring out into a tulip configuration, thus maintaining installation quality.
4Adaptability or versatility
If the blind fastener adapts to variations in grip length, then versatility is improved, but maintaining joint strength becomes more difficult
Solution Approach 1:
The patent designs the core bolt with a controlled break-off feature that allows the bolt length to be dynamically adjusted based on grip length variations. The frangible portion is positioned to break at a point that ensures the remaining bolt provides adequate thread engagement for maintaining joint strength, regardless of the specific grip length within the design range.
Data Source
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AI summary
A tool for installing a blind fastener including a bolt and a nut, the tool comprising: a driving member; a collet driven by the driving member for engaging the bolt; and an nosepiece for holding the nut and inhibiting the nut from rotating during installation of the blind fastener, the nosepiece being movable between a first position in which the nosepiece is driven by the collet to rotate with the collet and a second position in which the nosepiece is rotationally stationary despite rotating action of the collet.