Resistance Welding Stack-Up With Inverted ASM Placement

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Solution Overview

Problem

Current resistance welding processes for steel stack-ups with high thickness ratios face inefficiencies due to current density drops caused by adhesive/sealer materials (ASM) when applied between thinner and thicker sheets, resulting in insufficient weld penetration into the thinner outer sheet.

Innovation Solution

Applying a layer of ASM between the thicker outer and inner sheets instead of between the thinner and thicker sheets, generating extra heat to enhance weld penetration into the thinner outer sheet, and using a unified weld schedule with a robotic system for controlled heat input and sheet arrangement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a layer of adhesive/sealer material is placed between the thinner outer sheet and thicker inner sheet to increase heat generation, then weld penetration into the thinner sheet is improved, but current density drops due to the added ASM

Engineering Contradiction:

Improveweld penetration depthVSAvoidcurrent density stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent inverts the conventional placement of adhesive/sealer material by positioning it between the two thicker sheets instead of between the thin and thick sheets. This inversion allows the ASM to generate heat that penetrates through the thinner sheet without interfering with current density at the thin-sheet interface, thereby resolving the contradiction between improving weld penetration and maintaining current density stability

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent applies local quality by creating different thermal and electrical conditions at different locations in the stack-up. The ASM is strategically placed only between thicker sheets where its heat-generating property is beneficial, while the interface between the thinner sheet and adjacent sheet maintains direct electrical contact for optimal current density, thus locally optimizing both heat generation and electrical conductivity

Inventive Principle:

Principle #3Local quality

2Temperature

If adhesive/sealer material is added between sheets to improve weld penetration, then heat generation increases, but the process becomes less robust

Engineering Contradiction:

Improveheat generationVSAvoidprocess robustness

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

By inverting the placement location of the ASM from the conventional position (between thin and thick sheets) to the alternative position (between two thick sheets), the patent achieves heat generation improvement while avoiding the negative impact on process robustness that occurs when ASM is placed at the thin-sheet interface

Inventive Principle:

Principle #13The other way round (Inversion)

3Manufacturing precision

If conventional ASM placement is used between thinner and thicker sheets, then weld penetration is enhanced, but applicability to higher thickness ratios is limited

Engineering Contradiction:

Improveweld penetrationVSAvoidapplicability to thickness ratios

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The inverted placement of ASM between thicker sheets creates a more versatile welding process that can handle higher thickness ratios. The heat generated by the ASM propagates through the stack-up in a way that effectively reaches the thinner sheet regardless of the thickness ratio, thereby expanding adaptability while maintaining weld penetration

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the parameter of ASM placement position from the conventional location to an alternative location between thicker sheets. This parameter change enables the process to accommodate a broader range of thickness ratios while maintaining effective weld penetration into thinner sheets

Inventive Principle:

Principle #35Parameter changes

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 approach ensures deep weld penetration into the thinner outer sheet while avoiding current density drops, expanding the applicability to higher thickness ratios and providing multiple welding solutions based on stack-up thickness ratios.

Implementation Method 1

applying a layer of ASM between a thicker outer sheet of steel and an adjacent thicker inner sheet, thereby generating extra heat that increases penetration into a thinner outer sheet

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

resistance welding the stack according to a unified weld schedule such that weld penetration extends into the thinnest of the at least three steel sheets

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS20240165732A1Weldability in resistance welding of steels with large difference in sheet thickness

Publication Date: 2024.05.23 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A method for resistance welding at least three steel sheets, a weld structure produced by resistance welding at least three steel sheets and a method for determining weldability solutions when resistance welding at least three steel sheets in a stack are provided. By applying a layer of adhesive/sealer material between a thicker outer sheet of steel and an adjacent thicker inner sheet, thereby generating extra heat that increases penetration into a thinner outer sheet but with no layer of adhesive/sealer material between a thinner outer sheet and an adjacent thicker inner sheet, current density drop issues of a current process are addressed.