Self-Piercing Rivet Recess Geometry for Stable High-Tensile Joints
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Solution Overview
Problem
Self-piercing rivets used for joining high tensile and super high tensile steels often face issues such as asymmetrical spreading, shank bending, and difficulty in insertion, leading to potential rivet fracture and increased setting forces, which can result in damage to the rivet or workpieces during the joining process.
Innovation Solution
The introduction of an axial circular recess at the transition portion between the head and shank of the self-piercing rivet reduces setting forces by allowing the head protrusion to stand out radially, preventing cracks and maintaining stability, even when used with high tensile steels, and can be adapted for various materials including aluminum and standard steel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If self-piercing rivets are used for joining high tensile steels, then joint strength is achieved, but setting forces increase and rivet fracture occurs
Solution Approach 1:
The patent applies local quality by providing a chamfered transition portion between the head and shank with specific geometric parameters (chamfer angle α between 135° and 165°, radius R between 0.15-0.35mm). This localized geometric modification reduces stress concentration at the transition zone, allowing the rivet to withstand high setting forces without fracture while maintaining joint strength for high tensile steels.
2Strength
If self-piercing rivets are used for joining high tensile steels, then joint strength is achieved, but the rivet shank bends and spreading becomes asymmetrical
Solution Approach 1:
The patent applies local quality by providing a chamfered transition portion between the head and shank with specific geometric parameters (chamfer angle α between 135° and 165°, radius R between 0.15-0.35mm). This localized geometric modification reduces stress concentration at the transition zone, allowing the rivet to withstand high setting forces without fracture while maintaining joint strength for high tensile steels.
3Ease of manufacture
If self-piercing rivets are inserted into high tensile steel workpieces, then joining is achieved, but insertion difficulty increases and rivet fracture occurs
Solution Approach 1:
The patent applies local quality by providing a chamfered transition portion between the head and shank with specific geometric parameters (chamfer angle α between 135° and 165°, radius R between 0.15-0.35mm). This localized geometric modification reduces stress concentration at the transition zone, allowing the rivet to withstand high setting forces without fracture while maintaining joint strength for high tensile steels.
Data Source
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AI summary
Self-piercing riveted joint with a self piercing rivet and self-piercing rivet (10') for joining workpieces having a head (12') which comprises a head diameter, and having a shank (14') which comprises a shank diameter. The shank (14'), on the foot end (18') located opposite the head (12'), comprises an axial recess (22') which has an axial depth (LB'). The shank (14') comprises a flat surface portion (20) or a circular cutter on the foot end (18'). An axial circular recess is realized in a region of a transition portion (16') between the head (12') and the shank (14').