Dissimilar Conductor Joining with Undercut Grooves and Spot Welding

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Solution Overview

Problem

Existing methods for mechanically joining materials with different melting temperatures, such as adhesive and mechanical joints, face limitations including poor stress resistance, high variability, increased weight, and environmental impact, while conventional welding processes are ineffective for materials with varying melting points.

Innovation Solution

A method involving the creation of grooves on the surface of the material with the higher melting temperature, followed by resistance welding using a spot welding process with localized heating, where grooves are cut using a pulsed fibre laser, allowing for effective joining of materials like aluminium and titanium.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional welding processes are used to join materials with different melting temperatures, then one material can be brought to melting point, but the other material with lower melting temperature cannot be properly joined

Engineering Contradiction:

Improvejoint reliabilityVSAvoidmaterial compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention applies preliminary action by creating grooves on the surface of the material with higher melting temperature before welding. This pre-prepared surface geometry enables the lower melting temperature material to be properly joined by allowing it to flow into and fill the grooves during the welding process, ensuring reliable joint formation despite the melting temperature difference.

Inventive Principle:

Principle #10Preliminary action

2Strength

If adhesive joints are used to join materials, then shear stress resistance is improved, but peeling stress resistance remains poor and surface pre-treatments are required

Engineering Contradiction:

Improveshear stress resistanceVSAvoidsurface pre-treatment complexity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The invention replaces the adhesive mechanical system with a direct metallurgical bonding system through resistance welding. This substitution eliminates the need for adhesive surface pre-treatments while achieving strong joints through the grooves that facilitate material interlocking and bonding during the welding process.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If mechanical joints with external elements are used, then joining is achieved, but structure weight and costs increase

Engineering Contradiction:

Improvejoint formationVSAvoidstructure weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The invention merges the joining function directly into the material interface by creating grooves on the material surface itself. This eliminates the need for separate external joining elements like rivets or bolts, achieving reliable joint formation while reducing overall structure weight and manufacturing costs.

Inventive Principle:

Principle #5Merging (Combining)

4Adaptability or versatility

If thermal-mechanical joining processes are used to join different metals, then material compatibility is improved, but heat is ceded to surrounding areas and production times increase

Engineering Contradiction:

Improvematerial compatibilityVSAvoidheat loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The invention applies local quality by creating grooves only at the specific joining location where material compatibility is needed. This localized surface modification enables effective joining of different metals with varying thermal conductivities while confining thermal effects to the immediate joint area, minimizing heat loss to surrounding areas and reducing production time.

Inventive Principle:

Principle #3Local quality

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 high mechanical performance, reduced energy requirements, and low cycle times with minimal thermal alteration, resulting in strong and durable joints with high resistance to corrosion and easy integration into existing production systems.

Implementation Method 1

said cutting step is carried out by means of a laser technique

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

said joining step is carried out by means of a resistance welding, even more preferably by means of a spot welding

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 3

whereby the material with lower melting temperature is brought to melting point and fills the grooves

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentEP3659736B1Method to join materials with a different melting temperature

Publication Date: 2022.01.05 UNIV DEGLI STUDI DELLAQUILA

Figure 1~2

AI summary

A method to mechanically join two conductor materials with a different melting temperature. The method comprises, in succession: - a contact step, during which a surface of a material with a higher melting temperature, where there are grooves, is arranged in contact with a surface of a material with a lower melting temperature, and - a joining step, during which the two materials are subjected to a coupling pressure and, at the same time, are crossed through by a current at the plurality of grooves until the grooves are filled with said material with a lower melting temperature.; said grooves having an undercut profile.