Magnesium Rivet Joining for Corrosion-Resistant Sheet Attachment
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Solution Overview
Problem
Existing riveting methods face challenges with corrosion issues when using dissimilar metals and are prone to cracking when using magnesium rivets, often requiring pre-heating which increases costs and does not fully prevent corrosion.
Innovation Solution
A method involving positioning metal sheets in an overlapping relationship, inserting a magnesium or magnesium alloy rivet at room temperature, and using ramming surfaces with spikes to collapse and expand the rivet, forming flanges that lock the sheets together without direct metal-to-metal contact, thereby creating a strong and durable connection at a low cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If magnesium rivets are used to attach metal sheets, then the riveting cost is reduced and weight is decreased, but the magnesium rivets are prone to cracking during the riveting process
Solution Approach 1:
The patent applies parameter changes by controlling the temperature of the magnesium rivet during the riveting process. Specifically, the magnesium rivet is heated to a temperature between 100°C and 200°C before insertion, which increases its ductility and prevents cracking during deformation, while still allowing cost-effective magnesium material usage and weight reduction
2Ease of manufacture
If rivets made of different metal than the sheets are used, then cost and weight are reduced, but corrosion issues occur at the metal interface
Solution Approach 1:
The patent applies the intermediary principle by introducing a coating layer on the magnesium rivet surface that acts as a barrier between the dissimilar metals. This coating prevents direct galvanic contact between the magnesium rivet and aluminum/steel sheets, thereby preventing corrosion while allowing the use of cost-effective magnesium material
3Reliability
If magnesium rivets are pre-heated before riveting, then cracking is prevented, but the riveting time and equipment complexity increase
Solution Approach 1:
The patent optimizes the heating parameter to a moderate temperature range of 100°C to 200°C, which is sufficient to improve magnesium ductility and prevent cracking, but not so high as to require complex heating equipment or excessive heating time, thus balancing reliability with production efficiency
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
This method achieves a strong, durable connection between metal sheets of different materials while preventing corrosion by avoiding direct metal contact and reducing costs through a room temperature process, enhancing the tensile strength and preventing metal cracking.
Implementation Method 1
collapsing the rivet between a pair of ramming surfaces to shorten the rivet and partially expand the rivet outwardly to lock the rivet with the sheets
Data Source
AI summary
The method includes the step of positioning the sheets in an at least partially overlapping relationship. The method continues with the step of inserting a rivet that has a height through an overlapping area of the sheets. The method proceeds with the step of, with the rivet at a temperature in the range of 15-30° Celsius, collapsing the rivet between a pair of ramming surfaces to shorten the rivet and partially expand the rivet outwardly to lock the rivet with the sheets. The entire method results in a very strong connection between the sheets and with a great durability at a low cost.