Self-Piercing Rivet With Spiral Ribs for Joining Strength
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Solution Overview
Problem
Conventional self-piercing rivets face challenges with easy separation, high joining load, interference with other equipment, and reduced shear strength, leading to damaged joints and increased complexity in assembly processes.
Innovation Solution
A self-piercing rivet design featuring a solid circular shank with spiral ribs that allow for easy separation by torque and enhance shear strength, reducing joining load and interference, while maintaining structural integrity without cutting off the penetrated portion, thus enabling efficient joining and recycling of materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional self-piercing rivet with an annular piercing edge is used, then the rivet can penetrate the upper sheet, but the penetrated portion of the upper sheet is completely cut off, forming dead metal that cannot form mechanical interlock, which deteriorates joining strength
Solution Approach 1:
The piercing edge is segmented into multiple刀刃 (cutting edges) arranged radially around the shank axis, rather than a single annular edge. This segmentation allows the material to be cut and displaced in a controlled manner, forming protrusions that create mechanical interlock between sheets while avoiding complete cutoff of the penetrated portion
Solution Approach 2:
The cutting edges are designed with specific geometric characteristics (radial arrangement, specific angles) to create localized material displacement and deformation patterns. This local quality control ensures that the penetrated portion forms protrusions for mechanical interlock rather than being completely severed
2Stability of the object's composition
If multiple rivets are used to prevent rotation of the upper sheet, then rotation is prevented, but processes become complicated, productivity deteriorates, and product cost increases
Solution Approach 1:
The piercing edge geometry is designed in advance to inherently prevent rotation during the piercing process. The radial arrangement of cutting edges and their specific angular orientations create asymmetric material displacement that naturally resists rotational movement, eliminating the need for multiple rivets or additional anti-rotation measures
Solution Approach 2:
The cutting edges are asymmetrically arranged radially around the shank axis with specific angular positions. This asymmetric geometry creates inherent anti-rotation characteristics during piercing, as the material resistance varies with angular position, preventing the upper sheet from rotating freely
3Ease of manufacture
If the shank is formed with an annular piercing edge, then piercing is achieved, but the joining load increases due to the cutting action
Solution Approach 1:
The piercing process is made dynamic through the rotational movement of the rivet during piercing. The rotating cutting edges sequentially engage the material, converting part of the joining load into rotational motion and reducing the peak axial force required compared to a static cutting action
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 design allows for easy separation of joined objects without dismantling, enhances shear strength, reduces joining load and interference, and improves productivity by using fewer rivets, thereby addressing the limitations of conventional self-piercing rivets.
Implementation Method 1
the self-piercing rivet plastically deforms riveting target portions of an upper plate member and a lower plate member that are overlapped with each other to be integrally joined
Implementation Method 2
a plurality of ribs formed to an external circumferential surface of the shank portion from the connecting end to the free end in a spiral form
Data Source
AI summary
A self-piercing rivet is disclosed. The self-piercing rivet integrally joins an upper plate member and a lower plate member overlapping each other. The self-piercing rivet includes a head portion, a shank portion integrally connected with the head portion, and a plurality of ribs formed to an external circumferential surface of the shank portion along a length direction of the shank portion in a spiral form.