Blind Fastener Insert Bulb Formation Mechanism
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Solution Overview
Problem
Blind fasteners face challenges in securing work pieces with blind sides, as existing solutions often require access to the blind side, which is difficult or impossible, and existing bulbed sleeves do not effectively engage the blind side with a large enough footprint.
Innovation Solution
A fastener design featuring a sleeve, core bolt, and insert, where the insert is compressed to form a bulb at the blind side, using materials like copper and band annealing to enhance bulb formation, allowing secure engagement of work pieces without direct access to the blind side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a blind fastener is used to secure work pieces without accessing the blind side, then installation ease is improved, but the engagement footprint on the blind side is reduced
Solution Approach 1:
The patent changes the physical state and dimensions of the insert by compressing it axially during installation. This compression causes radial expansion of the insert, increasing its engagement footprint on the blind side of the work piece without requiring access to that side during installation. The insert transitions from a compact state during installation to an expanded state during service, resolving the contradiction between installation ease and engagement footprint.
2Strength
If the insert is compressed to form a larger bulb, then engagement strength is improved, but the complexity of the fastening system increases
Solution Approach 1:
The patent introduces an insert as an intermediary element between the sleeve and the work piece. This insert is specifically designed to be compressed during installation, causing it to expand radially and form a bulb that engages the blind side of the work piece. The insert mediates the force transmission from the sleeve to the work piece, enabling strong engagement without requiring complex threading or attachment mechanisms on the blind side, thus improving engagement strength while maintaining relatively simple system complexity.
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 design effectively secures work pieces by forming a bulb at the blind side, providing a robust and symmetrical engagement that is at least 1.5 times the diameter of the sleeve, preventing thread galling and ensuring a flush installation.
Implementation Method 1
The fastener is adapted to compress the insert between the step of sleeve and the thread run-out of the core bolt by an installation motion of the core bolt with respect to the sleeve before the installation motion of said core bolt generates a compressive load on the sleeve. The insert is adapted to deform away from the core bolt to initiate formation of a bulb adjacent the blind side of the plurality of work pieces in response to the compression.
Implementation Method 2
The insert is adapted to deform away from the core bolt to initiate formation of a bulb adjacent the blind side of the plurality of work pieces in response to the compression.
Implementation Method 3
The band annealed portion is band annealed by one of a laser and a radio frequency induction coil.
Implementation Method 4
The band annealed portion is band annealed by one of a laser and a radio frequency induction coil.
Implementation Method 5
The band annealed portion is band annealed by one of a laser and a radio frequency induction coil.
Data Source
AI summary
A fastener includes a sleeve, a core bolt, and an insert. The sleeve includes a first portion having a first inner diameter, a second portion having a second inner diameter, and a step intermediate the first and second portions. The core bolt includes a cylindrical portion having a first diameter, a threaded portion having a major diameter, and a thread run-out intermediate the cylindrical and threaded portions. The insert is disposed within the sleeve and is sized and shaped to be retained between the step of the sleeve and the thread run-out of the core bolt when the fastener is in a pre-installation position. The fastener compresses the insert between the step of the sleeve and the thread run-out of the core bolt by an installation motion of the core bolt. The insert deforms away from the core bolt to initiate formation of a bulb in response to the compression.