Self-Piercing Rivet Die Relief for Brittle Material Joining
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Solution Overview
Problem
Traditional self-piercing rivet (SPR) tools struggle to effectively join relatively brittle materials, such as aluminum castings, due to their ductile nature and the difficulty in deformation during the joining process.
Innovation Solution
A self-piercing rivet die and method that involves positioning the bottom substrate on the die and the top substrate on top of the bottom substrate, with a self-piercing rivet being pressed through both substrates. The die features a relief with a raised central portion, an outer portion, a side surface, and an annular channel, which helps deform the bottom substrate and guide the rivet, reducing strain and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional SPR tools are used to join brittle materials like aluminum castings, then the joining process can be performed, but the brittle materials are prone to strain and cracking during deformation
Solution Approach 1:
The die geometry parameters are specifically designed with a relief featuring a raised central portion, an outer portion, and an annular channel. This changes the deformation parameters and distribution, allowing the brittle material to be joined without excessive strain and cracking that would occur with traditional SPR tools.
Solution Approach 2:
The die relief structure acts as an intermediary between the rivet and the brittle substrate. The annular channel and raised portions guide and control the deformation process, mediating the stress distribution to prevent cracking in the brittle material during the joining process.
2Adaptability or versatility
If traditional SPR tools are used on ductile sheet metal, then the joining process works well, but the same tools fail to effectively join brittle materials
Solution Approach 1:
The die relief provides localized deformation zones with different geometric characteristics. The raised central portion, outer portion, and annular channel create distinct local regions that control material flow differently, enabling the same tool to effectively join both ductile and brittle materials by adapting the local deformation characteristics.
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 solution effectively joins brittle materials by reducing strain and cracking in the bottom substrate, allowing for reliable connections in applications where traditional SPR tools fail.
Implementation Method 1
pressing the self-piercing rivet deforms the bottom substrate into a relief defined by at least: a raised central portion of the die; an outer portion of the die disposed about a central axis of the die
Data Source
AI summary
A method of joining substrates includes positioning the substrates on a die and pressing a self-piercing rivet until it penetrates into the bottom substrate and deforms the bottom substrate into a relief of the die defined by at least: a raised central portion, an outer portion disposed about a central axis of the die, a side surface disposed about the central axis, and an annular channel disposed about the central axis and disposed, in a radial direction, between the raised central portion and the outer portion. The side surface connects the outer portion to the top surface. The annular channel is recessed axially from the raised central portion and at least a part of the outer portion that is adjacent to the annular channel. The annular channel is radially inward of a toe of the self-piercing rivet after the deforming the bottom substrate into the relief.