Ultrasonic Deformation Prediction for Compressor Discs
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Solution Overview
Problem
Machining of parts like compressor discs is hindered by deformation due to residual stress release, leading to financial losses from scrapped parts, as the variability in deformation makes it difficult to determine the optimal machining procedure, and increasing machining operations is costly.
Innovation Solution
A method involving the emission of ultrasonic waves onto a part's surface to measure the propagation velocity of subsurface longitudinal waves in stressed and unstressed zones, calculating the speed difference to predict deformation, and using a calibration curve to anticipate machining deformation, allowing for adaptive machining operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a greater number of machining operations are carried out to reduce deformation, then manufacturing precision is improved, but productivity deteriorates due to increased machining time and cost
Solution Approach 1:
The patent applies preliminary action by performing ultrasonic velocity measurements before machining to predict deformation. This allows the machining process to be planned in advance with the optimal number of operations determined beforehand, avoiding both excessive machining (which reduces productivity) and insufficient machining (which compromises precision). The calibration curve created beforehand enables direct prediction of deformation from velocity measurements.
2Productivity
If ultrasonic velocity measurement is performed to predict deformation, then productivity is improved by reducing unnecessary machining operations, but measurement precision is affected by the challenge of detecting subsurface stress
Solution Approach 1:
The patent uses ultrasonic waves as an intermediary to indirectly measure residual stress. Instead of attempting to measure stress directly (which would be difficult and imprecise), the method measures the velocity of ultrasonic waves propagating through the material, which changes in response to stress. This intermediary measurement approach enables accurate stress prediction while maintaining measurement feasibility.
Solution Approach 2:
The patent exploits parameter changes in ultrasonic wave velocity as a function of residual stress. By measuring changes in the velocity parameter of ultrasonic waves, the method indirectly quantifies stress levels. The calibration curve establishes the relationship between velocity changes and deformation, enabling precise prediction without directly measuring stress.
3Ease of operation
If traditional machining procedures are used without deformation prediction, then ease of operation is maintained, but loss of substance increases due to scrapped parts
Solution Approach 1:
The patent replaces the trial-and-error mechanical approach (performing multiple machining operations and hoping for acceptable results) with a non-contact ultrasonic measurement system. This substitution allows prediction of deformation before machining, enabling operators to adjust the machining plan accordingly and avoid scrapping parts, thus reducing material loss while maintaining operational simplicity through the use of standardized ultrasonic equipment.
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 method enables efficient and economical prediction of deformation, reducing the need for extensive machining operations, minimizing financial losses, and optimizing the machining process by determining the necessary number of operations based on predicted deformation values.
Implementation Method 1
emitting a beam of ultrasonic waves onto a surface of the part, the beam being oriented in such a way that a longitudinal wave propagates in a given direction under the surface of the part and substantially parallel to the surface
Implementation Method 2
a longitudinal wave propagates in a given direction under the surface of the part and substantially parallel to the surface
Implementation Method 3
The coupling element has the shape of a wedge and makes it possible to generate a longitudinal wave propagating obliquely in the piece to be analysed
Data Source
Figure 1~4
AI summary
The method involves emitting an ultrasound beam on a surface of a part (13) i.e. disk, and placing a receiver transducer (16) on the surface for receiving an ultrasound sub surface longitudinal wave (12). Propagation speed of the longitudinal wave is measured, where the emission, placement and measuring steps are carried in different zones and the zones are sensible to residual constraints. A difference between measured speeds in the zones is calculated, and the difference of deformation resulting from the machining of one of zones of the part, is deduced. The ultrasound beam is oriented such that the longitudinal wave propagates along ultrasound axis of transducer in a coupling part.