Rotor Disc Positioning via Laser Eccentricity Detection

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Solution Overview

Problem

Current methods for assembling gas turbine rotors are inefficient and prone to balancing errors due to lack of precision in positioning rotor discs, requiring extensive manual corrections and infrastructure, and existing solutions are not applicable to already assembled or overhauled rotors with deformed tie-rods.

Innovation Solution

A method and assembly using a main device coupled to a rotor disc and reference devices on the tie-rod, with lasers and photosensitive sensors to detect eccentricity, allowing for precise positioning and minimizing manual corrections by intercepting laser beams and providing objective measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the tie-rod is used as a reference for measuring eccentricity, then the measurement process is simplified, but the measurement precision deteriorates because the tie-rod is deformed by thermomechanical stresses

Engineering Contradiction:
Improvemeasurement process simplicityVSAvoideccentricity measurement accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent introduces a laser beam as an intermediary reference element that is not affected by the deformation of the tie-rod. The laser beam provides a stable, external reference for measuring the position of rotor discs, eliminating the dependency on the deformed tie-rod while maintaining measurement simplicity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If manual activities and personal assessments are used to control disc compliance, then device complexity is reduced, but measurement precision and reliability deteriorate

Engineering Contradiction:
Improvecontrol system simplicityVSAvoiddisc compliance detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces manual mechanical measurement activities with an optical measurement system using lasers and photosensitive sensors. This substitution eliminates human subjectivity and improves measurement precision while maintaining operational simplicity through automated detection.

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

3Productivity

If rotor discs are stacked without precise positioning control, then assembly time is reduced, but manufacturing precision deteriorates due to accumulation of errors

Engineering Contradiction:
Improveassembly speedVSAvoidrotor disc stacking accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent implements preliminary positioning control by measuring the eccentricity of each rotor disc before it is stacked onto the tie-rod. This preliminary measurement allows for corrective actions to be taken in advance, preventing the accumulation of positioning errors during the stacking process while maintaining efficient assembly speed.

Inventive Principle:
Principle #10Preliminary action

4Manufacturing precision

If corrective actions are taken after the rotor is clamped, then manufacturing precision can be improved, but loss of time increases due to disassembly and reassembly

Engineering Contradiction:
Improvedisc positioning accuracyVSAvoidcorrective operation duration
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent performs eccentricity measurements and positioning corrections before the rotor discs are firmly clamped and assembled. By conducting measurements and implementing corrective actions during the assembly process itself, the need for time-consuming disassembly and reassembly operations is eliminated.

Inventive Principle:
Principle #10Preliminary action

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 enables precise and reliable positioning of rotor discs, reducing balancing errors and minimizing corrective operations, especially for already assembled or overhauled rotors, by providing objective and accurate assessments without relying on deformed tie-rod references.

Implementation Method 1

at least three lasers emitters coupled to one between the main device and the at least one first reference device and at least three respective photosensitive sensors coupled to the other between the main device and the at least one first reference device

Methodology Applied
Scientific EffectLaser: Laser

Implementation Method 2

photosensitive sensors being arranged so as to intercept laser beams emitted by respective lasers emitters

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP3896252B1Method and assembly for controlling the positioning of at least one rotor disc about a tie-rod of a partially assembled rotor
Publication Date: 2023.04.12 ANSALDO ENERGIA SPA
  • EP3896252B1 patent drawingFigure 1
  • EP3896252B1 patent drawingFigure 2
  • EP3896252B1 patent drawingFigure 3~3A

AI summary

A method for controlling the positioning of at least one rotor disc (2) about a tie-rod (3) of a partially assembled rotor (1) of a gas turbine comprises: • positioning the tie-rod (3) so as its longitudinal axis (A) extends substantially vertically; • detecting the eccentricity of the rotor disc (2) with respect to the longitudinal axis (A) of the tie-rod by means of an assembly (23) comprising a main device (24) coupled to a free face (13a) of the rotor disc (2) and at least one first reference device (25, 26) coupled to the tie-rod (3); the assembly (23) further comprising at least three lasers emitters (28) coupled to one between the main device (24) and the at least one first reference device (25, 26) and at least three respective photosensitive sensors (30) coupled to the other between the main device (24) and the at least one first reference device (25, 26); the photosensitive sensors (30) being arranged so as to intercept laser beams (B) emitted by respective lasers emitters (28).