Blind Rivet Mandrel Length Optimization
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Solution Overview
Problem
The standardization of blind rivet mandrel length results in excessive material usage and costs, as the conventional 24.5 millimeters minimum dimension is not optimized for efficiency and cost-effectiveness, leading to significant waste and disposal issues, despite the need for sufficient surface area for gripping during installation.
Innovation Solution
A blind rivet design with a modified mandrel length between 6.35 millimeters and 19.05 millimeters, allowing for a smooth surface for gripping and a breakaway neck to fracture at a predetermined tensile load, compatible with conventional riveting tools, reducing material usage and costs while maintaining performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the conventional standardized mandrel length of 24.5 millimeters minimum is used, then sufficient surface area for gripping during installation is ensured, but excessive material usage and costs occur
Solution Approach 1:
The mandrel is segmented into two functional portions: a reduced-length exposed portion (6.35-19.05 mm) for gripping and a broken-off portion that remains within the rivet body. This segmentation allows the exposed portion to be optimized for minimal material while maintaining sufficient gripping surface area, resolving the contradiction between material reduction and gripping effectiveness.
Solution Approach 2:
The mandrel length parameter is changed from the conventional standardized minimum of 24.5 millimeters to a reduced range of 6.35-19.05 millimeters for the exposed portion. This parameter change reduces material usage while the broken-off mechanism ensures the gripping portion remains functional, thereby resolving the contradiction between quantity of substance and ease of operation.
2Loss of substance
If the conventional standardized mandrel length is used, then compatibility with existing riveting tools is maintained, but significant waste and disposal issues arise
Solution Approach 1:
The mandrel length parameter is optimized to a reduced range (6.35-19.05 mm exposed portion) while maintaining the broken-off mechanism that ensures compatibility with existing riveting tools. This parameter change reduces spent mandrel waste and disposal issues without sacrificing tool compatibility, resolving the contradiction between loss of substance and adaptability.
3Ease of manufacture
If the mandrel length is reduced to minimize material usage, then material costs are reduced, but sufficient gripping surface area during installation may be compromised
Solution Approach 1:
The mandrel is divided into a gripping portion (exposed, reduced length) and a structural portion (broken-off, remains in body). This segmentation allows optimization of the gripping portion for minimal material usage and cost efficiency while ensuring it maintains adequate surface area for tool engagement, resolving the contradiction between ease of manufacture and ease of operation.
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 modified blind rivet design achieves a substantial reduction in material usage and costs, with a 17% reduction in mandrel material for size #3 or #4 rivets, and up to 38% reduction in spent mandrel length, facilitating efficient production, use, and disposal, while maintaining compatibility with existing riveting tools.
Implementation Method 1
the mandrel 16 is generally designed to break away at or proximal to the head of the mandrel
Implementation Method 2
the rivet body 12 compresses longitudinally and expands radially outwardly to form a blind-side head
Data Source
Figure 1~4
Figure 5A~5B
Figure 6A~6B
AI summary
A blind rivet design has an exposed mandrel portion modified from the conventional and standardized mandrel to reduce amount and cost of materials required to produce the mandrel, while also minimizing costs related to production, use, and spent mandrel disposal, all while still making use of conventional riveting tools for rivet setting and maintaining rivet performance. The blind rivet also facilitates feeding of a shortened spent mandrel through conventional riveting tools and into mandrel collection devices.