Replaceable Friction Stir Welding Shoulder With Shrink-Fit Adapter

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Solution Overview

Problem

The existing friction stir welding devices require costly materials for the shoulder due to the integration of the shoulder distal and proximal ends, leading to high replacement costs when the shoulder distal end deteriorates, necessitating the replacement of the entire shoulder.

Innovation Solution

A friction stir welding device with a shoulder main body and adapter system, allowing for the shoulder main body to be easily detachable and replaceable through shrink-fitting, using different materials for the adapter and main body to reduce costs and facilitate maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the shoulder distal end and shoulder proximal end are integrated as a single component, then the structural strength and stiffness are improved, but the manufacturing cost and replacement cost increase significantly

Engineering Contradiction:

Improvestructural strengthVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The shoulder is divided into two separate components: the shoulder distal end (which contacts the workpiece) and the shoulder proximal end (which connects to the driver). This segmentation allows each component to be manufactured independently using appropriate materials and processes, reducing overall manufacturing cost while maintaining structural integrity through precise fitting interfaces between the segments.

Inventive Principle:

Principle #1Segmentation

2Strength

If the entire shoulder is made of expensive material (e.g., cemented carbide) to ensure high stiffness and abrasion resistance, then the performance is improved, but the unit price and replacement cost increase

Engineering Contradiction:

Improvestiffness and abrasion resistanceVSAvoidunit price

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

Different materials are selected for different regions of the shoulder based on functional requirements. The shoulder distal end, which requires high stiffness and abrasion resistance for contact with the workpiece, is made of expensive material such as cemented carbide. The shoulder proximal end, which does not require such high performance, is made of cheaper material such as steel, thereby reducing the overall unit price while maintaining necessary performance at the critical contact region.

Inventive Principle:

Principle #3Local quality

3Reliability

If the shoulder distal end develops defects (e.g., cracks) due to gradual abrasion, then the component needs renewal, but the integrated configuration requires replacement of the entire shoulder including the proximal end

Engineering Contradiction:

Improvecomponent durabilityVSAvoidreplacement cost and complexity

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

By segmenting the shoulder into replaceable distal and proximal ends, the design enables selective replacement of only the worn distal end component while retaining the functional proximal end. This significantly reduces replacement cost and complexity compared to replacing the entire integrated shoulder, while maintaining reliability by allowing timely renewal of the defect-prone distal end.

Inventive Principle:

Principle #1Segmentation

4Stability of the object's composition

If the shoulder is designed as an integrated component, then the structural integrity is improved, but the maintainability and ease of replacement deteriorate

Engineering Contradiction:

Improvestructural integrityVSAvoidmaintainability

Core Design Contradiction:

Stability of the object's compositionVSEase of repair

Solution Approach 1:

The shoulder is segmented into multiple components that are assembled together with precise fitting interfaces, maintaining structural integrity during operation. The segmentation enables easy disassembly and replacement of the distal end by detaching it from the proximal end, significantly improving maintainability while preserving the structural integrity needed for welding performance.

Inventive Principle:

Principle #1Segmentation

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 provides a cost-effective and maintainable friction stir welding device by allowing for the replacement of the shoulder main body independently, reducing maintenance costs and extending the device's lifespan.

Implementation Method 1

heating the shoulder adapter to increase a diameter of the fit hole of the shoulder adapter

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

a proximal end of the shoulder main body is shrink-fitted in the fit hole

Methodology Applied

Scientific EffectShrink-fitting: Thermal Contraction

Implementation Method 3

a rotating tool including: a pin or a probe that is rotatable about an axis

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12528138B2Friction stir welding device and maintenance method for same

Publication Date: 2026.01.20 KAWASAKI JUKOGYO KK

AI summary

A friction stir welding device includes: a pin extending along an axis; a shoulder having a cylindrical shape and coaxially surrounding an outer periphery of the pin; and a driver that allows the pin and the shoulder to rotate about the axis and to advance and retract along the axis individually. The shoulder includes a shoulder main body having a distal end to be plunged into a welding target, and a shoulder adapter having a fit hole in which a proximal end of the shoulder main body is shrink-fitted and connecting the shoulder main body and the driver to each other.