Stepped Fastener for Thick Sheet Metal Assembly
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Solution Overview
Problem
Existing fastening elements in car and truck manufacturing are not effectively designed for sheet metal parts thicker than 3 mm, leading to inefficiencies and limitations in production, especially for small quantities, as they often require pre-punching and deformation, which can compromise sheet metal properties and are not adaptable to varying thicknesses.
Innovation Solution
A fastening element system that includes a fastener with a cylindrical, stepped, or conically diverging hole design in the sheet metal part, allowing for secure attachment without deformation, and accommodating different sheet metal thicknesses by forming a rivet flange or bead that wedges into the perforation, ensuring stability and anti-rotation features, while maintaining the sheet metal in a planar state during attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If riveted fasteners are used for sheet metal parts thicker than 3 mm, then the fastening strength is improved, but the sheet metal properties are compromised due to pre-punching and deformation
Solution Approach 1:
The patent applies preliminary action by pre-forming conical recesses in the sheet metal part before inserting the fastener. This allows the rivet section to be crimped and expanded into the conical shape, creating a clamping grip without requiring aggressive deformation of the sheet metal itself. The conical recesses are prepared in advance to accommodate the fastener's expansion, thereby maintaining sheet metal properties while achieving strong fastening.
2Productivity
If welded elements are used instead of fastening elements, then the production efficiency is improved, but the sheet metal properties are compromised due to heat generation
Solution Approach 1:
The patent replaces the thermal welding process with a mechanical fastening system. Instead of using heat to join components, the invention uses mechanically deformed rivet sections that expand into conical recesses to create clamping grips. This mechanical substitution eliminates heat generation that would compromise sheet metal properties, while maintaining production efficiency through a process suitable for large quantities.
3Ease of manufacture
If standard rivets are used for thick sheet metal parts, then the manufacturing simplicity is improved, but the adaptability to different thicknesses is reduced
Solution Approach 1:
The patent applies local quality by providing conical recesses at specific locations in the sheet metal part where fasteners will be inserted. These conical recesses are tailored to local thickness requirements, allowing the same fastener design to adapt to varying sheet metal thicknesses. The local conical geometry enables the rivet section to expand and create effective clamping grips regardless of the overall sheet thickness.
Solution Approach 2:
The patent achieves universality by designing a fastener system that can handle a wide range of sheet metal thicknesses (3 mm to 6.5 mm and beyond) using the same basic fastener element. The conical recess configuration and rivet section expansion mechanism provide multi-functionality, allowing the system to adapt to different thicknesses without requiring entirely different fastener designs.
4Strength
If the sheet metal part is deformed into a conical shape for clamping grip, then the fastening strength is improved, but the planarity of the sheet metal is lost
Solution Approach 1:
The patent applies preliminary action by pre-forming conical recesses in the sheet metal part before fastener installation. These recesses create the necessary conical geometry locally at the fastening point without deforming the entire sheet metal part. The sheet metal remains planar in the immediate area and in radial directions adjacent to the attachment point, while the clamping grip is achieved through the pre-formed conical recess.
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3A~3C
AI summary
The assembly component has a fastening element (10) and a sheet metal part. The fastening element has a flange unit (12) of larger diameter and a shaft unit (14) of smaller diameter. The fastening element is designed for application with sheet metal part with thicknesses in the range of 3 millimeter and more. An independent claim is included for a method for manufacturing assembly component.