Rotor-Casing Clearance Measurement via Piano Wire Reference
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Solution Overview
Problem
In the assembly of large rotating machines like gas turbines and steam turbines, ensuring accurate clearance measurements between the rotor and casing is challenging due to deflection and distortion, leading to potential misalignment and breakage risks, and existing methods are cumbersome and prone to human error in calculating corrections.
Innovation Solution
A system that specifies measuring points for misalignment between the rotor and casing, records measurement results, and automatically calculates corrections using an input terminal unit and database, allowing for precise adjustments based on predicted values and weighting coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If measurements are taken at all points (including non-measurable points) to ensure accurate clearance verification, then measurement precision is improved, but device complexity and time consumption increase significantly
Solution Approach 1:
The patent uses wiring (piano wire) as a physical copy or reference model of the rotor shaft center position. By measuring clearances relative to this wire copy rather than directly measuring at all points on the rotor, the system achieves accurate clearance verification while reducing measurement complexity. The wire serves as an intermediary reference that simplifies the measurement process.
Solution Approach 2:
The patent introduces an intermediary reference system (wiring) between the measurement instrument and the rotor. This intermediary allows indirect measurement of clearances at non-measurable points through calculation based on measurements taken at accessible points, thereby achieving comprehensive clearance verification without requiring direct access to all points.
2Measurement precision
If manual calculations are performed for each non-measurable point to determine clearance values, then measurement precision is maintained, but productivity and ease of operation deteriorate due to cumbersome calculations
Solution Approach 1:
The patent implements a computer-based system that automatically performs the correction calculations that previously required manual intervention. The system self-services by taking measurement data from measurable points, automatically calculating clearance values at non-measurable points using stored correction parameters, and outputting results without requiring workers to perform manual calculations, thereby significantly improving productivity while maintaining precision.
Solution Approach 2:
The patent replaces the manual mechanical calculation process with an automated computer-based calculation system. Instead of workers manually computing clearance values at non-measurable points, the system uses a computer to automatically perform the calculations based on measurement data and pre-stored correction parameters, eliminating the time-consuming manual calculation step.
3Manufacturing precision
If correction parameters are determined based on empty weight and rigidity of casing and rotor, then manufacturing precision is improved, but device complexity and ease of manufacture worsen due to complicated parameter determination
Solution Approach 1:
The patent determines correction parameters in advance during the design and manufacturing phase, before the actual assembly and measurement process. By pre-calculating and storing correction parameters based on the empty weight and rigidity characteristics of the casing and rotor, the system eliminates the need for complex real-time calculations during assembly, thereby improving manufacturing precision while simplifying the assembly process.
Data Source
AI summary
In each work process of the assembly work of a large rotating machine, an input terminal unit 101 displays measuring points necessary for measurements of radial and axial clearances between a rotor and a casing so as to provide workers with instructions. When workers measure the clearances at the instructed measuring points, the measured values will be supplied to the input terminal unit 101 so as to confirm whether the measured values are within design tolerances or not. In addition, when workers measure the clearances at the instructed measuring points, amounts of adjustment of the casing will be displayed so that the measurement results at the measuring positions will have an optimum positional relation with the designed values.