Automobile Panel Roll-Fastening for Strength and Aesthetics
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Solution Overview
Problem
Existing panel fastening methods for automobiles, particularly those with three-dimensional shapes, face challenges in achieving high fastening strength and aesthetic quality while minimizing fabrication steps, often requiring additional processes like spot welding and seal coating, and can result in wrinkles and poor outlook due to limitations in hem flange design and bonding techniques.
Innovation Solution
A panel fastening method involving roll-fastening of overlapped plate members with specific thickness and curvature considerations to ensure strong pinching and bonding, where the front end faces are rolled-in to form a hem portion with sufficient gaps and controlled curvature, reducing the need for additional steps like spot welding and seal coating, and allowing for concealed bonding portions for improved aesthetics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hemming structure with folding to bend hem flange is used to fasten panels, then fastening strength is improved, but number of fabricating steps increases due to need for adhering agent coating, spot welding, and seal member coating
Solution Approach 1:
The invention combines multiple fastening functions into a single roll-fastening operation. The roll-fastening process simultaneously achieves panel fastening, sealing, and structural bonding without requiring separate steps for adhering agents, spot welding, or seal member coating, thus reducing the total number of fabricating steps while maintaining fastening strength.
Solution Approach 2:
The roll-fastening structure serves multiple functions: it provides mechanical fastening strength through the rolled hem portion, creates a seal to prevent rust and dust ingress, and bonds panels together structurally. This multi-functional approach eliminates the need for separate components like seal members and adhering agents, simplifying the manufacturing process.
2Manufacturing precision
If hem flange is shortened at corner portion to prevent wrinkle, then wrinkle prevention is improved, but outlook quality deteriorates
Solution Approach 1:
The invention uses roll-fastening which creates a curved, rounded hem portion instead of sharp folds. This curved structure naturally distributes stress and prevents wrinkle formation at corner portions without requiring shortening of the hem flange, thereby maintaining both manufacturing precision and aesthetic outlook quality.
3Strength
If folding to bend operation is applied with force in widening direction, then fastening is achieved, but sagging occurs due to increased radius of curvature deteriorating outlook
Solution Approach 1:
The roll-fastening process creates a controlled curved hem portion with optimized radius of curvature. This curved structure achieves fastening through the rolling action itself rather than through forceful folding that widens the radius, thereby preventing sagging and maintaining outlook quality while ensuring adequate fastening strength.
4Strength
If multiple fastening methods (adhering agent, spot welding) are used to compensate for deficiency, then fastening strength is improved, but device complexity increases
Solution Approach 1:
The invention merges the fastening function into a single roll-fastening operation that provides sufficient strength without requiring multiple separate fastening methods. The rolled hem portion creates a strong mechanical bond between panels, eliminating the need for adhering agents and spot welding, thus improving fastening strength while reducing device 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
This method enhances fastening strength and aesthetic quality by ensuring firm pinching and bonding without visible bonding portions, reducing fabrication steps, and preventing wrinkles, while accommodating variations in plate thickness and curvature, thus improving the overall outlook and durability of the panel.
Implementation Method 1
roll-fastening of overlapped plate members with specific thickness and curvature considerations to ensure strong pinching and bonding
Implementation Method 2
front end faces are rolled-in to form a hem portion
Data Source
AI summary
A panel member for an automobile includes a hem portion roll-fastened in a state of overlapping an outer panel and an inner panel. At the hem portion of the panel member, the outer panel and the inner panel are roll-fastened in a state that a front end face of the outer panel and a front end face of the inner panel are respectively rolled-in by the inner panel and the outer panel.