Adaptive Trailing Edge Machining for Buckled Turbine Blades
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Solution Overview
Problem
Current foundry techniques are unable to produce turbomachine blades with trailing edge thicknesses as low as 0.2mm or 0.5mm required for improved aerodynamic performance, due to deformations resembling buckling, which cannot be adequately addressed by simple machining.
Innovation Solution
An adaptive machining method using a numerically controlled machine tool that adjusts its trajectory to the blade's geometry, with excess thickness removal on both surfaces and correction based on deformation measurements, allowing for precise reduction of the trailing edge thickness while accounting for buckling deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If foundry casting techniques are used to manufacture turbine blades, then production efficiency is improved and complex blade shapes can be obtained directly, but the trailing edge thickness cannot be reduced below approximately 0.7mm due to buckling deformations
Solution Approach 1:
The patent applies preliminary action by introducing excess thickness in the trailing edge region during the casting process. This excess material is deliberately created to compensate for the limitations of casting techniques, allowing subsequent machining operations to achieve the required thin trailing edge dimensions (0.2-0.5mm) while maintaining the efficiency benefits of direct casting for complex blade geometries.
2Manufacturing precision
If simple machining is applied to reduce trailing edge thickness, then some thickness reduction is achieved, but the buckling deformations in the raw cast parts prevent achieving the desired fineness
Solution Approach 1:
The patent prepares the workpiece in advance by creating excess thickness in the trailing edge region during casting. This preliminary action transforms the difficult task of machining highly deformed thin sections into a more manageable operation where the excess material provides a buffer against buckling deformations, enabling achievement of 0.2-0.5mm thickness targets.
Solution Approach 2:
The patent changes the geometric parameters of the cast part by intentionally introducing excess thickness in specific regions (trailing edge). This parameter modification allows the subsequent machining process to work with more favorable starting conditions, reducing the impact of buckling deformations and enabling precision thin trailing edge production.
3Manufacturing precision
If adaptive machining with trajectory adjustment is used, then high machining precision and aerodynamic profile are achieved, but the process complexity increases
Solution Approach 1:
The patent implements feedback by using a probe to measure the actual geometry of the blade trailing edge during machining. These measurements are fed back to the control system, which automatically adjusts the tool trajectory in real-time to compensate for deviations from the nominal geometry, ensuring high precision aerodynamic profiles despite variations in the cast part quality.
Solution Approach 2:
The patent applies dynamics by making the machining tool trajectory adaptive rather than fixed. The tool path is dynamically adjusted based on real-time measurements of the workpiece geometry, allowing the machining process to respond to actual part variations and achieve consistent high precision results across different castings.
Data Source
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AI summary
The present invention relates to a method for manufacturing a turbine engine blade, the blade comprising an airfoil and the profile of the airfoil being defined by a theoretical digital model, including the manufacture of a blank having a thickened portion along the trailing edge of the airfoil relative to the theoretical profile, characterized in that said thickened portion is removed by adaptive machining, including the following steps: positioning the blank in a reference frame; acquiring, by probing at a predetermined number of points (Ni) on a first surface of the blank along the trailing edge, the position of said points in the reference frame; determining the differences, in one direction, in the delta position (Ni) from corresponding points of the theoretical model; producing machining grids on said surface of the blank, the peaks of the grids being determined from said points (Ni); determining the amount of material to be removed from the surface of the grids, said amount being based on the position of the points (Nc) of the grid relative to the peaks of the grids and said deviations in position; and machining the airfoil.