Perforated Interlayer Stackup for Resistance Spot Weld Quality

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current resistance spot welding processes often result in undesirable phenomena such as expulsion, sharp whiskers, cracks, and undesirable heat affected zones, which compromise joint strength and manufacturing efficiency.

Innovation Solution

A combined stackup apparatus for resistance spot welding that includes a perforated interlayer between two metal sheets, with perforations of specific sizes and open areas, made from materials like steel or aluminum, which helps control expulsion and forms a weld nugget within the perforations, reducing sharp formations and improving joint strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional resistance spot welding is used to join metal sheets, then welding process simplicity is maintained, but undesirable phenomena occur including expulsion, sharp whiskers, cracks, and undesirable heat affected zones

Engineering Contradiction:

Improvejoint strengthVSAvoidexpulsion and sharp formations

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A perforated interlayer is introduced between the metal sheets to be welded. This interlayer acts as a mediator that controls the welding process by providing a structured interface for weld nugget formation, containing expulsion within its perforations, and preventing direct contact between base metals that would otherwise form sharp whiskers and cracks.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The interlayer is designed with a perforated structure containing multiple holes of specific sizes and distributions. This porous configuration allows controlled expulsion of welding material through the perforations while maintaining structural integrity, and provides nucleation sites for weld nugget formation that prevent undesirable sharp formations.

Inventive Principle:

Principle #31Porous materials

2Strength

If welding parameters are increased to improve joint strength, then weld nugget size increases, but heat affected zone expands and causes more damage

Engineering Contradiction:

Improvejoint strengthVSAvoidheat affected zone

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

The perforated interlayer creates localized welding zones at each perforation site. The welding energy is concentrated at these specific locations rather than being distributed across the entire interface, allowing strong weld nuggets to form locally while limiting the overall heat affected zone to small regions around each perforation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The welding interface is segmented into multiple discrete perforation sites rather than a continuous contact area. This segmentation allows the welding process to occur at multiple isolated points, distributing the heat input and preventing large-scale heat affected zones while maintaining overall joint strength through multiple weld points.

Inventive Principle:

Principle #1Segmentation

3Object-generated harmful factors

If perforation size is increased to control expulsion, then expulsion is reduced, but weld nugget formation is restricted

Engineering Contradiction:

Improveexpulsion controlVSAvoidweld nugget formation

Core Design Contradiction:

Object-generated harmful factorsVSStrength

Solution Approach 1:

The interlayer contains multiple perforations with sizes optimized for partial expulsion control. Rather than using a single large perforation that would completely contain expulsion, multiple smaller perforations are used to achieve progressive control of expulsion while providing sufficient space for adequate weld nugget formation at each site.

Inventive Principle:

Principle #16Partial or excessive action

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 use of a perforated interlayer in resistance spot welding reduces expulsion, enhances weld joint ductility and strength, and improves heat affected zone formation, resulting in more robust and reliable welds by controlling heat concentration and minimizing stress concentrations.

Implementation Method 1

improves heat affected zone formation... by controlling heat concentration

Methodology Applied

Scientific EffectHeat concentration:

Implementation Method 2

resistance spot welding

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11471972B2Combined stackup apparatus for resistance spot welding

Publication Date: 2022.10.18 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A combined stackup apparatus with a perforated interlayer for resistance spot welding is provided. The apparatus comprises a first metal sheet of a first material and a second metal sheet of a second material. The apparatus further comprising a perforated interlayer disposed between the first metal layer and the second metal layer. The perforated interlayer is made of one of the first and second materials. The perforated interlayer has a plurality of perforations formed therethrough. Each perforation has a perforation size of between about 0.1 mm and about 3 mm.