Profiled FSW Head Piece for Welding Height-Difference Joints

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Solution Overview

Problem

Friction stir welding technologies face challenges in reliably welding workpieces with height differences, such as overlap joints or butt joints of different thicknesses, leading to inconsistent joint quality and susceptibility to crevice corrosion.

Innovation Solution

A head piece for the welding tool with a profiled end face featuring end face areas of different heights, connected by a slanted shoulder that guides the plasticized material, compensates for height differences and ensures precise alignment, thereby improving the welding process and joint strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional headpiece design is used for friction stir welding, then welding of workpieces with height differences can be performed, but joint quality is inconsistent and susceptible to crevice corrosion

Engineering Contradiction:
Improvejoint quality consistencyVSAvoidcrevice corrosion susceptibility
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The headpiece is designed with end face areas of different heights (first and second end face areas) to match the height differences between overlapping workpieces. This local variation in geometry ensures uniform contact pressure and consistent material flow across the entire weld interface, eliminating gaps that would otherwise lead to crevice corrosion and quality inconsistencies.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention introduces a vertical height dimension variation on the headpiece end face by creating multiple end face areas at different elevations. This dimensional change allows the headpiece to accommodate workpieces of different thicknesses and overlap heights, ensuring consistent welding quality across the entire joint interface.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If headpiece with uniform end face is used, then manufacturing is simple, but it cannot compensate for height differences in workpieces

Engineering Contradiction:
Improveability to handle height differencesVSAvoidheadpiece structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The headpiece incorporates locally varied end face areas with different heights, allowing it to adapt to different workpiece configurations. The first and second end face areas are positioned to match specific workpiece height variations, providing targeted compensation without requiring complete redesign of the entire headpiece structure.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The headpiece end face is segmented into multiple distinct areas (first end face area, second end face area) with different heights. This segmentation allows each area to independently interact with corresponding workpiece regions, providing adaptability to height differences while maintaining a relatively simple overall headpiece structure.

Inventive Principle:
Principle #1Segmentation

3Reliability

If overlapping workpieces are welded close to edges, then gap sealing is improved, but stress concentration may occur

Engineering Contradiction:
Improvegap seal integrityVSAvoidstress distribution
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The profiled end face with varying heights creates a localized geometry that distributes stress more evenly across the weld interface. By matching the headpiece geometry to the workpiece overlap configuration, the invention reduces stress concentration at the edges while maintaining effective gap sealing in the critical overlapping regions.

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

The solution enhances the quality and strength of welded joints by tightly sealing gaps and improving structural integrity, particularly in overlap joints, while preventing crevice corrosion and ensuring effective tension distribution.

Implementation Method 1

friction stir welding

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

plasticizing welding medium

Methodology Applied
Scientific EffectPlasticity: Plasticity

Data Source

PatentEP3801972B1Head piece, welding tool, welding device, and welding method for friction stir welding
Publication Date: 2024.11.27 KUKA DEUT GMBH
  • EP3801972B1 patent drawingFigure 1~2
  • EP3801972B1 patent drawingFigure 3~4
  • EP3801972B1 patent drawingFigure 5~6

AI summary

The invention relates to a head piece (3) and to a welding tool (1), in particular an FSW tool, equipped therewith, and to a welding method. The head piece (3) has a through-opening (4) for a plasticising welding means (2), in particular a rotating welding pin. The head piece (3) also has a profiled end face (13) which faces the workpiece (7, 8) during welding and has end face regions (14, 15) of different heights and a sloping shoulder (17) which conducts the plasticised material of the workpiece (7, 8) and connects the end face regions (14, 15).