Blind Rivet with Breakable Mandrel for Tack Fastening
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Solution Overview
Problem
Existing blind rivets for tack riveting provide insufficient installed tension and require specialized tools for removal, which can damage assembled elements and are not adaptable to varying thicknesses of the elements being assembled.
Innovation Solution
A blind rivet design featuring a deformable hollow sleeve with a tapered portion that facilitates deformation and crimping, allowing for increased tightening tension and adaptable to different thicknesses, and a breakable mandrel that can be removed using the same setting tool without damaging the assembled elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a blind rivet is used for tack riveting, then the elements can be positioned and coupled, but the installed tension provided is very little which is disadvantageous for permanent fastening
Solution Approach 1:
The mandrel is segmented into a first portion and a second portion, with the first portion being crimped onto the sleeve to provide installed tension, while the second portion remains breakable for removal. This segmentation allows the rivet to provide both temporary positioning and permanent fastening capabilities.
Solution Approach 2:
The first portion of the mandrel is pre-configured to be crimped onto the sleeve during installation, creating installed tension before the rivet is even used for permanent fastening. This preliminary action ensures that the elements are pre-tensioned, improving both positioning accuracy and fastening quality.
2Ease of repair
If specialized tools are used for removal of the rivet, then the rivet can be removed, but the tools can damage the elements to be assembled
Solution Approach 1:
The rivet is designed to be self-removable by using the same setting tool that installed it. The breakable mandrel allows the tool to engage and pull out the mandrel without requiring specialized removal tools, and the controlled breakage prevents damage to the elements.
Solution Approach 2:
The second portion of the mandrel is designed as a disposable component that breaks during removal. This allows simple removal mechanics without complex reusable parts, and the broken remnants can be easily extracted without damaging the expensive elements being assembled.
3Adaptability or versatility
If rivets of a plurality of dimensional models are used, then different thicknesses of elements can be assembled, but the device complexity increases
Solution Approach 1:
The sleeve includes a variable geometry portion that can be deformed to different extents, allowing a single rivet model to accommodate different element thicknesses. By changing the deformation parameter during installation, the same rivet can adapt to various thickness combinations without requiring multiple dimensional models.
4Force
If the mandrel is not fixed to the sleeve upon completion of deformation, then the sleeve can be deformed freely, but it is not possible to create a true tightening load or installed tension
Solution Approach 1:
The mandrel is divided into a first portion that is crimped to the sleeve and a second portion that breaks. The first portion creates installed tension by being crimped onto the sleeve, providing both tightening load and connection strength, while the second portion allows for removal.
Solution Approach 2:
The first portion of the mandrel and the sleeve are merged through crimping, creating a fixed connection that generates installed tension. This merging ensures that the tightening load is effectively transferred and maintained, while the overall design still allows for removal via the breakable second portion.
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 rivet achieves enhanced installed tension and adaptability to various thicknesses, enabling efficient assembly and easy removal without specialized tools, ensuring the integrity of the assembled elements.
Implementation Method 1
the sleeve being preformed from a single tapered portion positioned between the two support surfaces... under the action of a tension deformation on the mandrel, forms a bulb
Implementation Method 2
under the action of a tension effort on the mandrel, forms a bulb that defines a second support surface... causing the two support surfaces to be drawn nearer each other
Data Source
AI summary
A method of operating with a rivet is for the coupling and the tack riveting together of a first element and a second element. The method comprises positioning the rivet such that the rivet traverses two substantially coaxial openings arranged in the first and second elements to be assembled; pulling the mandrel to form a bulb on the second end; and resuming pulling of the mandrel, to cause a rupture of the sleeve at the bulb so as to permit removal, by way of the external surface of the first element, of the mandrel and of a first portion of the sleeve as well as the falling away of the portion of the bulb remaining on the external surface of the second element.