Dual-Cylinder Self-Piercing Rivet to Prevent Lower-Member Cracking

Solution Overview

Problem

Existing self-piercing rivets face challenges in maintaining manufacturing efficiency while reducing the thickness of the cylindrical part to prevent cracking in the lower fastened member, and there is a need for a simpler configuration to enhance fastening strength.

Innovation Solution

A self-piercing rivet with an outer and inner cylindrical part, each with a specific inclination, is driven into overlapping fastened members, allowing radial deformation to enhance fastening strength while maintaining efficiency and reducing thickness, thereby minimizing cracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the cylindrical part of the self-piercing rivet is thickened to ensure fastening strength, then the fastening strength is improved, but the lower fastened member is more likely to crack during driving

Engineering Contradiction:

Improvefastening strengthVSAvoidcrack in lower fastened member

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The cylindrical part is divided into an outer cylindrical part and an inner cylindrical part that are spaced apart from each other. This segmentation allows each part to have reduced thickness while collectively providing the necessary fastening strength through their combined structural support and deformation characteristics.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If the thickness of the cylindrical part is reduced to suppress cracking in the lower fastened member, then the crack risk is reduced, but the fastening strength decreases

Engineering Contradiction:

Improvecrack in lower fastened memberVSAvoidfastening strength

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The cylindrical part is divided into an outer cylindrical part and an inner cylindrical part that are spaced apart from each other. This segmentation allows each part to have reduced thickness while collectively providing the necessary fastening strength through their combined structural support and deformation characteristics.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If a double-tube structure with staggered driving timing is used to reduce cylindrical part thickness, then the thickness is reduced, but the manufacturing efficiency decreases and structure becomes more complex

Engineering Contradiction:

Improvecrack in lower fastened memberVSAvoidmanufacturing efficiency

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The outer cylindrical part and inner cylindrical part are designed to be driven simultaneously into the overlapping part during a single driving operation. This merging of the driving process eliminates the need for staggered timing control, thereby maintaining manufacturing efficiency while achieving reduced thickness.

Inventive Principle:

Principle #5Merging (Combining)

4Object-affected harmful factors

If a double-tube structure with staggered driving timing is used to reduce cylindrical part thickness, then the thickness is reduced, but the structural complexity increases

Engineering Contradiction:

Improvecrack in lower fastened memberVSAvoidstructure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The outer cylindrical part and inner cylindrical part are designed to be driven simultaneously into the overlapping part during a single driving operation. This merging of the driving process eliminates the need for staggered timing control, thereby maintaining manufacturing efficiency while achieving reduced thickness.

Inventive Principle:

Principle #5Merging (Combining)

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 proposed rivet configuration effectively suppresses cracking in the lower fastened member while maintaining manufacturing efficiency and enhancing fastening strength with a simplified structure.

Implementation Method 1

the tip side deforms radially outward when driven into the overlapping part

Methodology Applied

Scientific EffectRadial deformation: Deformation

Implementation Method 2

the tip side deforms radially outward or radially inward when driven into the overlapping part

Methodology Applied

Scientific EffectRadial deformation: Deformation

Data Source

PatentUS12372110B2Self-piercing rivet and manufacturing method for fastening structure

Publication Date: 2025.07.29 TOYOTA JIDOSHA KK

AI summary

A self-piercing rivet includes a head, an outer cylindrical part extending from the head and formed in a cylindrical shape, and an inner cylindrical part extending from the head, provided spaced apart inside the outer cylindrical part, and formed in a cylindrical shape. In the manufacturing method for a fastening structure, a self-piercing rivet is driven into an overlapping part of a first fastened member and a second fastened member to fasten the first fastened member and the second fastened member.