Adaptive CNC Machining of Cast Parts With Probe-Based Toolpath Alignment
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Solution Overview
Problem
Conventional methods for machining cast parts, such as gas turbine engine airfoils, face challenges with surface irregularities, increased cycle time, and dimensional inconsistencies due to the removal of support and gating features, which are exacerbated by manual and hard-coded robotic methods.
Innovation Solution
An autonomous adaptive machining method using a CNC machine that generates a nominal toolpath, applies a transformation matrix based on probe data to adjust for actual part alignment, and removes features identified during inspection, reducing the need for full 3D scanning and computer-aided manufacturing toolpath computation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual methods such as belt grinding are used to remove support and gating features, then surface irregularities are removed, but cycle time increases and dimensional inconsistencies worsen
Solution Approach 1:
The patent replaces manual mechanical methods (belt grinding, hand working) with an automated CNC machining system. The controller automatically generates and executes machining operations based on probe data, eliminating the need for manual intervention while maintaining surface quality and reducing cycle time.
Solution Approach 2:
The system performs self-inspection and self-correction through the probing mechanism. The probe automatically measures the workpiece, identifies deviations from nominal dimensions, and the controller automatically adjusts the machining toolpath to compensate for these variations without human intervention.
2Extent of automation
If hard-coded robotic or CNC methods are used for feature removal, then automation is achieved, but adaptability to part-to-part variance is lost
Solution Approach 1:
The system incorporates a feedback loop where the probe measures actual workpiece dimensions, compares them to nominal values, and the controller uses this information to dynamically adjust the machining toolpath. This closed-loop approach enables the automated system to adapt to part-to-part variations while maintaining high automation levels.
Solution Approach 2:
The machining system transitions from static, pre-programmed toolpaths to dynamic, adaptive toolpaths. The controller modifies machining parameters and trajectories in real-time based on probe measurements, allowing the system to respond to actual workpiece geometry rather than relying on fixed programs.
3Measurement precision
If full 3D scanning and computer-aided manufacturing toolpath computation are used, then complete inspection is achieved, but cycle time and computational complexity increase
Solution Approach 1:
The system extracts only the essential measurement data needed for machining from the workpiece surface using the probe. Instead of capturing complete 3D geometry, it selectively measures critical features and dimensions required for toolpath adjustment, reducing data processing requirements while maintaining machining precision.
Solution Approach 2:
The system performs partial inspection focused specifically on features relevant to machining operations. Rather than scanning the entire workpiece surface, it probes only the areas that will be machined or that define critical dimensions, reducing measurement time and computational load while ensuring adequate inspection for the machining task.
Data Source
AI summary
A method of removing features from a cast workpiece includes generating a nominal toolpath for machining the cast workpiece. The cast workpiece is mounted onto a platform of a computer numeric control machine. The cast workpiece is inspected with a probe to generate probe data. Features to be removed are identified based upon the probe data generated during the inspection. Any expected features of the cast workpiece that are missing from the cast workpiece are identified. A transformation matrix is applied to the nominal toolpath with a controller of the computer numeric control machine, wherein the transformation matrix is based upon the probe data. Alignment of the cast workpiece is adjusted relative to the computer numeric control machine based on the transformation matrix with the computer numeric control machine. Features are removed from the cast workpiece that were identified during inspection.