Blind Fastener Head Verification for Low-Profile Installation
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Solution Overview
Problem
The installation of blind fasteners in aeronautical structures poses challenges due to the difficulty in controlling the installation without access to the blind side, potential damage to composite materials, and the aerodynamic impact of conventional indentations, which affect the quality of the assembly and the cosmetic appearance.
Innovation Solution
A tool is designed that includes a laying member to create a bulb by rotating the rod until it breaks and a verification member that applies a torsional stress to the detachable head portion, ensuring correct installation by breaking it if installed properly, thus avoiding protrusions and allowing visual verification of correct installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional indentations are provided on the head of the blind fastener for installation and control, then the installation and maintenance functions are enabled, but the aerodynamic footprint and cosmetic appearance are degraded
Solution Approach 1:
The head of the blind fastener is segmented into a permanent retention portion and a detachable portion. The detachable portion is removed after installation, leaving only the permanent retention portion with minimal footprint on the assembly surface, thus resolving the contradiction between installation functionality and aerodynamic/cosmetic quality.
Solution Approach 2:
The detachable portion is pre-configured on the head to enable installation and control functions during the installation process. After serving its purpose, it is deliberately removed, leaving the permanent retention portion that maintains the fastener without compromising aerodynamic or cosmetic properties.
2Object-affected harmful factors
If the rod is broken to prevent protrusion after installation, then the aerodynamic footprint is reduced, but the installation control becomes more difficult without access to the blind side
Solution Approach 1:
The detachable portion of the head acts as an intermediary that remains attached during installation to enable control and verification functions. After installation is confirmed, it is removed, leaving the permanent retention portion that prevents protrusion while maintaining aerodynamic quality.
Solution Approach 2:
The fastener system includes built-in verification mechanisms where the detachable portion's removal itself serves as confirmation of proper installation. The system self-verifies through the controlled removal process, eliminating the need for additional external verification equipment.
3Difficulty of detecting and measuring
If a detachable portion is added to the head for verification purposes, then the installation control is improved, but the device complexity increases
Solution Approach 1:
The head is divided into two functional segments: a permanent retention portion that remains on the assembly and a detachable portion used for installation verification. This segmentation adds verification capability while keeping the permanent structure simple and aerodynamic.
Solution Approach 2:
The detachable portion is designed to be temporarily attached during installation, serve its verification function, and then be discarded (removed). This approach adds verification capability without requiring permanent complex structures on the fastener.
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
The tool ensures precise installation with minimal aerodynamic footprint and cosmetic impact, providing a reliable method for verifying correct tension and bulb formation without the need for additional machining, ensuring the fastener meets mechanical performance standards.
Implementation Method 1
The rod is conventionally preformed with a break groove so that once a predefined stress threshold has been reached, the rod breaks.
Implementation Method 2
the verification member subjecting the detachable portion of the head of the outer body to a torsional stress by a shock-type rotation drive which allows the production of a significant dynamic force produced in a very short time
Data Source
Figure 1a~1b
Figure 1c
Figure 2a
AI summary
The invention relates to a setting method and a setting tool (O) for a blind fastener (100) comprising a shank (110) on which an external body (120) is threaded, said external body (120) comprising a deformable portion (140) for the purpose of creating a bulb under the action of the shank (110), the shank (110) comprising a breaking groove (114), the tool being noteworthy in that it comprises a setting member (200) that cooperates with said shank (110) and a setting verification member (300) that cooperates with said head (121) of the external body (120), - the setting member (200) acting on the shank (110) in order to create the bulb until the shank (110) breaks in the region of the breaking groove (114), - the setting verification member (300) subjecting the detachable portion (122) of the head (121) of the external body (120) to a twisting stress by driving in rotation of the impact type in order to break the narrowed portion (123) of the external body (120), the break resulting in proper fitting and the absence of a break resulting in incorrect fitting. The invention also relates to a suitable blind fastener. Applications: setting of blind fasteners.