Integrally Bladed Rotor Positioning Using Priority Surface Reference

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Solution Overview

Problem

The challenge in fabricating integrally bladed rotors for gas turbine engines is achieving accurate complex geometry of airfoil surfaces due to manufacturing tolerances, which affects engine performance.

Innovation Solution

The method involves selecting a finished surface of the blades as a reference surface for positioning during welding, rather than the nominal surface, to minimize geometry variations, and determining a priority surface based on functionality to ensure accurate placement and welding of blades to the hub.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the nominal surface is used as the reference surface for positioning blades during welding, then the manufacturing process is simpler, but the positioning accuracy and final geometry precision deteriorate due to accumulated tolerances

Engineering Contradiction:

Improvesimplicity of positioning processVSAvoidaccuracy of airfoil surface geometry

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

Instead of using the nominal surface (theoretical design surface) as the reference for positioning, the patent inverts the approach by using the finished surface (actual manufactured surface) as the reference. This inversion allows the positioning to be based on the actual physical surface that already incorporates manufacturing tolerances, thereby eliminating the accumulation of tolerances between nominal and finished surfaces.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The finished surface of the blade serves its dual purpose: it is both the final aerodynamic surface and the reference surface for positioning during welding. The blade's own finished surface provides the reference information needed for accurate positioning, eliminating the need for separate reference surfaces or additional measurement and compensation steps.

Inventive Principle:

Principle #25Self-service

2Adaptability or versatility

If manufacturing tolerances are applied to blade positioning, then the manufacturing process becomes more flexible, but the accuracy of the complex airfoil geometry deteriorates

Engineering Contradiction:

Improveflexibility in manufacturingVSAvoidaccuracy of blade position and geometry

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The finished surface is created first through manufacturing processes, and then this pre-created surface is used as the reference for positioning. By performing the manufacturing action first and then using its result as the reference, the system accommodates manufacturing flexibility while ensuring that the positioning is based on the actual finished geometry rather than theoretical nominal dimensions.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If multiple tolerance additions are considered in blade positioning, then all manufacturing variations are accounted for, but the complexity of the positioning process and calculation increases

Engineering Contradiction:

Improvecompleteness of tolerance considerationVSAvoidcomplexity of positioning system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the reference surface directly from the finished blade surface itself, rather than attempting to calculate and incorporate multiple tolerance values into a complex positioning system. By taking out the reference information directly from the physical finished surface, the system eliminates the need for complex tolerance stacking calculations while maintaining reliability.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS9498857B2Method of fabricating integrally bladed rotor using surface positioning in relation to surface priority

Publication Date: 2016.11.22 PRATT & WHITNEY CANADA CORP

AI summary

A method of fabricating an integrally bladed rotor for gas turbine engines according to one aspect includes a step of positioning a blade on a hub in a joining procedure by using a priority surface of the blade as a reference surface. The priority surface is determined in relation to importance of surface functionality of the blades during engine operation.