Blind Rivet Friction Fit Grip Strength
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Solution Overview
Problem
Existing blind fasteners face challenges in securely fastening workpieces without requiring manual handling and in providing consistent grip strength, especially in softer and thinner materials, due to limitations in manufacturing complexity and cost.
Innovation Solution
A blind fastener design featuring a sleeve and pin with a shear ring and interference fit, where the pin has a grip section that forms a friction fit with the sleeve, allowing for easy installation and providing high shear and tensile strength through a wide bearing surface on the blind side, facilitating controlled expansion and reduced manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional blind fastener designs are used, then installation is relatively simple, but grip strength is insufficient especially in softer and thinner materials
Solution Approach 1:
The pin is divided into multiple sections with different diameters: a first section with a larger diameter that forms an interference fit with the sleeve bore, and a second section with a smaller diameter. This segmentation allows the fastener to provide enhanced grip strength through the interference fit while maintaining manageable structural complexity through the defined geometric sections.
Solution Approach 2:
The pin features localized variations in diameter along its length, with the first section having a larger diameter specifically at the location where interference fit with the sleeve is required. This local quality change provides enhanced grip strength precisely where needed without unnecessarily complicating the entire fastener structure.
2Ease of operation
If manual handling is required for installation, then grip strength can be maintained, but installation complexity and time increase
Solution Approach 1:
The fastener design enables self-service installation through the interference fit mechanism. The pin's first section with larger diameter automatically forms an interference fit with the sleeve bore during installation, creating self-aligning and self-securing features that eliminate the need for manual handling adjustments and reduce installation time.
3Strength
If interference fit is implemented to improve grip, then manufacturing precision requirements increase
Solution Approach 1:
The invention utilizes controlled parameter changes in the pin diameter along its length. The first section has a specifically designed larger diameter that creates the interference fit, while the second section has a reduced diameter. This parameter variation allows the interference fit to provide enhanced shear and tensile strength while the overall design remains manufacturable with standard tolerance ranges.
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 solution enables secure fastening with improved grip strength over an extended range, reduced manufacturing costs, and ease of production, while ensuring the fastener remains securely in place under dynamic loads and vibrations.
Implementation Method 1
the grip portion is in the head bore and forms a friction fit with the head bore to prevent the installed sleeve from inadvertently coming free of the installed pin
Data Source
AI summary
A blind fastener has a sleeve and a pin. The sleeve has a shank with a shank bore and a head with a head bore smaller than the shank bore. The pin has a pin installation portion with a proximal end portion and a distal end portion. The pin also has a breakaway portion with a pin grip, and a pin break groove between the installation portion and the breakaway portion. The pin further has a grip portion at the proximal end portion of the pin installation portion and directly adjacent to the pin break groove. In a pre-installation configuration, the grip portion is in the sleeve bore. In an installation configuration, the grip portion is in the head bore and forms a friction fit with the head bore to prevent the installed sleeve from inadvertently coming free of the installed pin.