Vented Friction Stir Channelling for Consistent Curved Channels

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Solution Overview

Problem

Existing friction stir channelling methods result in rough surface finishes, inconsistent channel cross-sections, and excessive material displacement, particularly when forming serpentine or curved channels, due to the progressive build-up of heat and viscoplastic property changes in the workpiece material.

Innovation Solution

A friction stir channelling tool with a rotating probe and a non-rotating shoulder featuring vents to extract plasticised material from the workpiece, promoting uniform channel formation by directing material into the tool's bore and allowing controlled extraction through multiple vents, which improves cornering performance and maintains consistent channel profiles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If friction stir channelling is used to create channels in workpieces, then channels can be formed for fluid flow, but the surface finish becomes rough with crescent patterns and the channel cross-section fluctuates

Engineering Contradiction:

Improvechannel cross-section consistencyVSAvoidsurface finish quality

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent changes the geometric parameters of the tool, specifically using a probe with threads or flutes and a shoulder with vents, to control material flow and extraction. This modifies the processing parameters to achieve consistent channel cross-sections and smooth surface finishes while maintaining the friction stir channelling process

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If material is displaced during friction stir channelling, then channels are formed, but excess material is deposited on surfaces creating flash and rough surfaces

Engineering Contradiction:

Improvechannel formation accuracyVSAvoidmaterial debris and flash

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the harmful excess material during the processing operation itself by incorporating vents in the shoulder that allow plasticised material to be removed through the tool. This prevents flash formation and surface roughness caused by deposited material, while still achieving proper channel formation

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The vented shoulder acts as an intermediary mechanism that captures and removes excess material during processing. The vents provide a controlled path for material extraction, preventing it from being deposited on the workpiece surface where it would create harmful flash and roughness

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If processing continues through serpentine or curved channels, then complex geometries are achieved, but heat build-up changes material viscoplastic properties causing channel cross-section fluctuations

Engineering Contradiction:

Improvecomplex channel geometry capabilityVSAvoidchannel cross-section consistency

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The vented shoulder provides continuous feedback by allowing excess material to escape during processing. This prevents material build-up that would otherwise alter viscoplastic properties and cause channel cross-section fluctuations, enabling consistent channel formation even through complex serpentine or curved geometries where heat build-up occurs

Inventive Principle:

Principle #23Feedback

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 achieves a smooth surface finish, consistent channel profiles, and effective control over material extraction, reducing the need for post-processing finishing and enabling the formation of channels with stable cross-sections, particularly beneficial for complex geometries and heat exchanger applications.

Implementation Method 1

friction stir channelling, where the friction stir process is modified so as to intentionally cause material to be moved from the bulk of the workpiece

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

causing the rotating probe to enter a workpiece... whereby rotation of the probe causes material of the workpiece around the probe to be plasticised

Methodology Applied

Scientific EffectPlasticity: Plasticity

Implementation Method 3

the displaced material is typically deposited just under the tool shoulder (which typically has a degree of clearance from the workpiece)... the viscoplastic material is driven towards the surface

Methodology Applied

Scientific EffectViscoplastic flow:

Data Source

PatentUS11020817B2Method and apparatus for creating channels in workpieces

Publication Date: 2021.06.01 THE WELDING INST

AI summary

A friction stir channelling tool comprises a probe (2) for inserting into a workpiece or workpieces. The probe (2) extends from, and is rotatably mounted in, a bore (14) of a shoulder (3), the probe surface being formed so as to cause plasticised workpiece material to be moved towards the shoulder and into the bore of the shoulder upon rotation of the probe while the shoulder is in contact with the workpiece. The shoulder (3) has at least one vent (4) extending from outside the shoulder to the bore (14) whereby the plasticised material can exit the bore through the vent.