Adaptive Machining for Smelted Turbine Blades
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Solution Overview
Problem
The 'lost wax' technique for manufacturing turbine engine blades results in dimensional irregularities and precision issues due to discrepancies between the reference points on the root and the vane, leading to time-consuming and imprecise machining processes, especially when dealing with thin faces and ventilation air evacuation vents.
Innovation Solution
An adaptive machining method is employed, where a grid is defined on the theoretical profile of the component to guide the machine tool, allowing it to adapt to the geometry of the blank component, ensuring precise removal of thickened portions and achieving tangential continuity between the machined and original surfaces by calculating and applying delta differences at each node, using weighting coefficients to position the tool accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the reference for positioning the blade is taken on the root of the blade, then the machining process can be implemented, but dimensional irregularities and lack of precision occur at the connection between the surface of the vane and the machined surface
Solution Approach 1:
The reference system is segmented into multiple local reference points distributed across the blade surface rather than relying on a single root reference. This segmentation allows each local area to have its own precise reference, eliminating cumulative errors and improving connection precision at the vane-machined surface interface.
Solution Approach 2:
The reference system transitions from a one-dimensional root-based linear reference to a two-dimensional or three-dimensional distributed reference network across the blade surface. This dimensional expansion enables precise positioning at multiple locations simultaneously, resolving the precision issue at the vane connection area.
2Manufacturing precision
If a digitally controlled machine tool is used for finishing operations, then dimensional irregularities are avoided, but the complexity of the machining system increases
Solution Approach 1:
The patent replaces complex mechanical positioning systems with a computational approach. Instead of using sophisticated mechanical reference systems and alignment mechanisms, the invention uses computer-based calculations to determine tool positions based on measured blade geometry, substituting mechanical complexity with computational simplicity.
Solution Approach 2:
The machining system uses the blade itself as its own reference by measuring the actual blade geometry and using those measurements to guide the machining process. The blade provides its own reference information through measurement, eliminating the need for external complex positioning systems.
3Shape
If the thickened portion is removed by machining using traditional reference calibration, then the required profile is achieved, but the process is time-consuming and produces projections on the surface
Solution Approach 1:
The patent performs preliminary measurement and calculation of the blade geometry before machining begins. By pre-calculating the exact tool paths and positions based on measured reference points, the actual machining process can proceed directly without time-consuming trial adjustments and reference recalibrations, significantly reducing total process time.
Solution Approach 2:
The machining process incorporates feedback from actual blade measurements. The measured geometry of the blade feeds into the calculation system, which then adjusts the tool paths accordingly. This closed-loop feedback ensures the required profile is achieved precisely while minimizing machining time through optimized tool paths.
Data Source
AI summary
A method for finishing a shape of a component by machining, in which one area is produced by smelting with a thickened portion forming a first surface with a surrounding profile and a theoretical profile defined by a second surface, the method including: defining, on the second surface, a grid forming nodes and squares; defining each point over which the machining tool is to pass according to weighting coefficients equal to weight to be given to the nodes of the square in which the tool is located, to be the barycenter of assigned nodes of the coefficients; measuring, for each node located outside an outer limit, the delta between the first surface at the node and the theoretical position of the node; calculating deltas for each node within the outer limit by interpolation from already known deltas; using the weighting coefficients, defining the delta to be applied at each point.