Adhesive Joining of Dissimilar Metals Using Resistance Pre-Curing

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Solution Overview

Problem

Spot welding of dissimilar materials, such as high-strength steel with mild steel or aluminum, often results in inadequate weld penetration and joint strength due to differences in material resistivity.

Innovation Solution

A method involving the dispensing of adhesive on one workpiece, contacting a second workpiece with the adhesive, and using resistance heating to partially cure the adhesive, followed by full curing at elevated temperatures, to join dissimilar metal workpieces effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If spot welding is used to join dissimilar materials (high-strength steel with mild steel or aluminum), then the joining process is simple and fast, but the weld penetration is inadequate and joint strength is insufficient due to differences in material resistivity

Engineering Contradiction:

Improvejoining speedVSAvoidweld penetration and joint strength

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent introduces adhesive as an intermediary substance between dissimilar metal workpieces that have different electrical resistivities. The adhesive layer mediates the joining process by providing a bonding interface that compensates for the inadequate weld penetration caused by resistivity differences, allowing effective joining of high-strength steel with mild steel or aluminum alloys

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical and chemical parameters of the adhesive through controlled curing processes. By adjusting curing temperature and time parameters, the adhesive transitions from a liquid state to a cured solid state with optimized bonding properties, enabling strong joints between dissimilar materials while maintaining process efficiency

Inventive Principle:

Principle #35Parameter changes

2Strength

If self-piercing rivets are used to mechanically fasten dissimilar materials, then joint strength can be improved, but the process becomes impractical when one workpiece is high-strength steel due to the high hardness and difficulty for rivets to penetrate

Engineering Contradiction:

Improvejoint strengthVSAvoidmanufacturing feasibility

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical fastening system (self-piercing rivets) with a chemical bonding system (adhesive). This substitution eliminates the need for mechanical penetration of the high-strength steel workpiece, making the manufacturing process practical and feasible while maintaining strong joint strength through adhesive bonding

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If adhesive is used to join dissimilar materials, then joint strength and reliability are improved, but the process requires multiple steps (dispensing, resistance heating, external heating) increasing process complexity

Engineering Contradiction:

Improvejoint reliabilityVSAvoidprocess complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple heating functions into a single resistance heating step. The resistance heating process simultaneously performs partial curing of the adhesive and prepares the workpieces for final curing, combining what would otherwise be separate operations. This integration reduces process complexity while maintaining high joint reliability through proper adhesive curing

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

This method achieves strong and reliable joints between dissimilar metals by ensuring adequate adhesive curing and bonding, even when traditional spot welding methods fail due to material differences.

Implementation Method 1

producing resistance heating in the first and second workpieces at first processing conditions to partially cure the adhesive

Methodology Applied

Scientific EffectResistance heating: Joule Heating

Implementation Method 2

exposing the partially cured, adhesive-joined workpiece assembly to heat at second processing conditions to substantially fully cure the adhesive

Methodology Applied

Scientific EffectHeat treatment: Heating

Data Source

PatentUS12290871B2Method and system for joining workpieces

Publication Date: 2025.05.06 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

Methods and systems for joining multiple workpieces are provided. In one example, the method includes dispensing adhesive on a first workpiece. A second workpiece is contacted with the adhesive such that the adhesive is disposed between the first and second workpieces. Resistance heating is produced in the first and second workpieces at first processing conditions to partially cure the adhesive and affix the first and second workpieces together to form a partially cured, adhesive-joined workpiece assembly. The partially cured, adhesive-joined workpiece assembly is exposed to heat at second processing conditions to substantially fully cure the adhesive.