Spline Feature Machining in Aircraft Engines Using Compensation Tables
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Solution Overview
Problem
Machining discrepancies in aircraft engine components, such as spline couplings, occur due to variances between the expected and actual positions of cutting tools, leading to manufacturing inaccuracies and complexities in calculating precise profiles.
Innovation Solution
A method involving the determination of actual target point positions on a machined surface, computation of position corrections using a compensation table, and definition of a corrected tool path to achieve the final shape, allowing for precise machining of features like grooves in spline connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a rotating cutting tool is used to machine spline teeth and grooves, then the machining process can be completed, but variances between expected and actual tool positions result in manufacturing discrepancies
Solution Approach 1:
The patent applies preliminary action by measuring the actual positions of target points on the semi-finished workpiece before completing the machining process. These measurements are used to calculate correction values that are stored in a compensation table, enabling the system to pre-determine the adjustments needed to compensate for positioning variances before final machining occurs.
Solution Approach 2:
The patent implements feedback by using a measurement system to detect actual tool positions and workpiece features, then feeding this information back into the control system. The measured deviations are processed to generate correction values that are applied to subsequent machining operations, creating a closed-loop control system that continuously improves positioning accuracy.
2Manufacturing precision
If correction values are calculated for each target point to compensate for position variances, then machining precision is improved, but the complexity of the machining process increases
Solution Approach 1:
The patent applies copying by creating a digital representation of the correction values in the form of a compensation table. This table stores the relationship between measured deviations and required corrections, allowing the system to reference pre-calculated correction values rather than performing complex real-time calculations during machining, thereby simplifying the control process while maintaining high precision.
Solution Approach 2:
The patent changes parameters by transforming the raw measurement data into corrected positioning parameters through the compensation table. The system modifies the tool path parameters based on the stored correction values, adjusting positions, depths, and other machining parameters to compensate for earlier positioning errors without requiring complex real-time computations.
3Measurement precision
If multiple target points are measured and correction tables are generated, then position accuracy is improved, but the time required for measurement and correction increases
Solution Approach 1:
The patent applies preliminary action by performing measurements and generating compensation tables during idle time or between machining operations, rather than during active machining. This allows the system to prepare correction data in advance, so that when actual machining occurs, the corrections can be applied immediately without adding to the critical machining cycle time.
Solution Approach 2:
The patent uses copying by storing correction values in a compensation table that can be rapidly referenced during machining. Once the comprehensive correction table is generated through detailed measurements of multiple target points, this single table serves as a lookup reference for all subsequent operations, avoiding the need to repeat time-consuming measurements for each feature while maintaining high position accuracy.
Data Source
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AI summary
A method of manufacturing a feature (F; 44, 46) in a part (B) with a cutting tool (C; 50), includes machining a semi-finished shape of the feature (F; 44, 46), determining an actual position of at least one target point (P1, P2, P3; P11, P12, P14, P14) on a surface (S1; SS1) of the semi-finished shape, and computing a difference between the determined position of the at least one target point (P1... P14) and a nominal position of the at least one target point (P01, P02, P03; P011) on a digitized model of the part (B) having the semi-finished shape of the feature (F; 44, 46). As a function of the difference, a correction to a position of the cutting tool (C; 50) on a nominal tool path to achieve the final shape of the feature (F; 44, 46) from the semi-finished shape is determined, and the correction is used to define a corrected tool path. The finished shape of the feature (F; 44, 46) is then machined with the cutting tool (C; 50) by moving the cutting tool along the corrected tool path.