Multi-Material Annular Power Transmission Member With Friction Stir Welding

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Solution Overview

Problem

Existing power transmission members made from a single material like steel are heavy, and those made from two materials require complex assembly and machining, leading to reliability issues and costly logistics due to the need for precise centering and screw-based attachment.

Innovation Solution

A power transmission member composed of three structurally distinct annular parts, where the torque transmission part is made of a denser material like steel, and the other two parts are made of less dense materials like aluminum, with axial abutment and friction stir welding for assembly, preventing axial and rotational displacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a power transmission member is made from a single material like steel, then mechanical strength is ensured, but weight becomes excessive

Engineering Contradiction:
Improvemechanical strengthVSAvoidweight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The power transmission member is divided into three annular parts made of different materials: a first annular part (lighter material), a second annular part with torque transmission means (denser material for strength), and a third annular part (lighter material). This segmentation allows each part to be optimized for its specific function, reducing overall weight while maintaining necessary mechanical strength in critical areas.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different materials are assigned to different parts based on their specific functional requirements. The torque transmission means (second annular part) uses a denser material with higher strength, while the non-critical first and third annular parts use lighter materials. This local differentiation of material properties optimizes the weight-strength balance by applying high-strength material only where absolutely necessary.

Inventive Principle:
Principle #3Local quality

2Weight of moving object

If a power transmission member is made from two materials with screw-based attachment, then weight is reduced, but assembly complexity and machining requirements increase

Engineering Contradiction:
ImproveweightVSAvoidassembly complexity
Core Design Contradiction:
Weight of moving objectVSDevice complexity

Solution Approach 1:

The three annular parts are merged into a single integral structure through friction stir welding, eliminating the need for separate attachment components like screws and centering machinings. This merging simplifies the assembly process while maintaining the weight benefits of using multiple materials with different densities.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If screw-based attachment is used to fix the veil and teeth, then assembly is achieved, but reliability decreases due to potential disassembly

Engineering Contradiction:
ImproveassemblyVSAvoidreliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The separate parts are merged into an integral structure through friction stir welding, creating a permanent joint that eliminates the reliability issues associated with screw-based attachments. The welded structure prevents disassembly while maintaining manufacturing feasibility, thus improving reliability without sacrificing ease of manufacture.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The mechanical screw-based attachment system is replaced with friction stir welding, which creates a metallurgical bond between the parts. This substitution eliminates the potential for disassembly and loosening associated with mechanical fasteners, thereby improving reliability while maintaining ease of manufacture through a streamlined welding process.

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

4Manufacturing precision

If centering machining is performed to ensure coaxiality of the shaft and veil, then assembly precision is achieved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvecoaxiality precisionVSAvoidmachining complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The three annular parts are merged into a single integral structure through friction stir welding, which inherently maintains coaxiality and alignment. This eliminates the need for separate centering machining operations, reducing manufacturing complexity while maintaining the precision required for proper power transmission.

Inventive Principle:
Principle #5Merging (Combining)

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 design reduces the weight of the power transmission member, enhances mechanical characteristics, and eliminates the need for complex assembly and costly logistics by creating a rigid and reliable connection without traditional welding defects.

Implementation Method 1

the second piece blocked longitudinally between the first annular piece and the third annular piece

Methodology Applied
Scientific EffectAxial abutment: Mechanical Force

Implementation Method 2

The welding of the first part to the third part can be carried out by friction mixing

Methodology Applied
Scientific EffectFriction stir welding: Friction Welding

Data Source

PatentEP3620685B1Power transmission member
Publication Date: 2021.09.29 SAFRAN TRANSMISSION SYST
  • EP3620685B1 patent drawingFigure 1~2
  • EP3620685B1 patent drawingFigure 3A~4B
  • EP3620685B1 patent drawingFigure 5~7

AI summary

The invention relates to an annular power transmission element 22 with longitudinal axis X comprising a first annular piece 26a, a second annular piece 26b comprising torque transmission means 46a and a third annular piece 26c joined together, the first annular piece 26a and the third annular piece 26c being made of a first metallic material, the second annular piece 26b being made of a second metallic material having a density greater than the density of the first metallic material, the second annular piece 26b being locked longitudinally between the first annular piece 26a and the third annular piece 26c and radially on the first annular piece 26a, the first annular piece 26a being in contact with the third annular piece 26c and welded to it.