Flat Component Joining by Friction Stir Welding

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Solution Overview

Problem

Existing methods for connecting flat components with different material properties, such as in bimetallic tubing, are complex and prone to contamination, especially in achieving high-strength and corrosion-resistant 'black-and-white' connections, as seen in fusion welding processes which involve high heat and risk of brittle intermetallic phases.

Innovation Solution

The method involves positioning flat components with aligned side surfaces for friction stir welding, using a rotating tool to generate frictional energy, and optionally connecting end surfaces via a separate part, reducing heat influence and avoiding brittle phases, allowing for simple and high-quality connections of components like structural steel and stainless steel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If fusion welding is used to connect flat components with different material properties, then high strength connection is achieved, but heat influence increases and brittle intermetallic phases form

Engineering Contradiction:
Improveconnection strengthVSAvoidheat influence and brittle phases
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the thermal field of fusion welding with a mechanical field using friction stir welding. A rotating tool with a pin and shoulder generates frictional heat locally while mechanically stirring the materials, achieving metallurgical bonding without the extensive heat-affected zone and intermetallic phase formation characteristic of fusion welding processes.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental welding parameters from high-temperature fusion welding to controlled friction-based solid-state welding. The process operates at temperatures below the melting point of the base metals, using friction heat to soften the material locally while maintaining overall low heat input, thereby avoiding brittle intermetallic phases.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If friction stir welding is used to connect flat components, then heat influence is reduced and brittle phases are avoided, but manufacturing complexity increases

Engineering Contradiction:
Improveheat influence and brittle phasesVSAvoidmanufacturing simplicity
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent segments the welding process into distinct functional components: a rotating pin for material stirring, a shoulder for applying compressive force and containing the material, and a controlled feed direction for progressive welding. This segmentation allows each component to be optimized independently while simplifying the overall manufacturing process through modular tool design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a specialized friction stir welding tool as an intermediary device that mediates between the two different materials. The tool's pin and shoulder work together to locally soften, mix, and bond the dissimilar materials through controlled friction and mechanical stirring, simplifying the connection of components with different material properties.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If a connecting part is used to indirectly connect components, then adaptability and versatility are improved, but device complexity increases

Engineering Contradiction:
Improveconnection flexibilityVSAvoidnumber of components
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent designs the friction stir welding tool with a universal pin geometry that can weld various material combinations and thicknesses by adjusting process parameters. The same basic tool design can connect different flat component configurations (T-joints, corner joints, lap joints) without requiring completely different tooling, thereby achieving versatility without proportional increases in complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 enables efficient, cost-effective, and high-quality connections of flat components with different material properties, reducing production costs and avoiding the need for entire pipe cross-sections of expensive corrosion-resistant steel, while minimizing embrittlement and heat influence, suitable for producing composite elements like bimetallic tubes with enhanced corrosion resistance and strength.

Implementation Method 1

frictional energy for connecting the components is generated by a wear-resistant rotating tool

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

the components are connected on at least some of the aligned side surfaces by means of friction stir welding

Methodology Applied
Scientific EffectFriction welding: Friction Welding

Data Source

PatentEP3691827B1Method for connecting flat components and compound element
Publication Date: 2021.09.08 STIRTEC GMBH
  • EP3691827B1 patent drawingFigure 1~2
  • EP3691827B1 patent drawingFigure 3~4
  • EP3691827B1 patent drawingFigure 5

AI summary

The invention relates to a method for connecting flat components (2). In order to produce a composite element (1) from components (2) of a wide variety of materials in a simple manner, it is provided according to the invention that the components (2) are positioned flat against one another, wherein side surfaces (4) of the components (2) are arranged at least partially in alignment, after which the components (2) are connected to at least a part of the aligned side surfaces (4) by means of friction stir welding. The invention further relates to a composite element (1) comprising at least two connected flat components (2).