Five-Axis CNC Rotary Axis Error Compensation via Volumetric Optimization
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Solution Overview
Problem
Current methods for improving the machining accuracy of five-axis CNC machine tools, particularly for rotary axes, face limitations due to identification and compensation inefficiencies, especially when dealing with large and complex parts, as they require extensive CNC instruction corrections and are sensitive to tooling errors.
Innovation Solution
A method involving the establishment of a volumetric positioning error model based on geometric errors, decomposition into linear and nonlinear correlations, and the use of a non-dominated sorting genetic algorithm (NSGAII) for optimization, which generates correction coefficients to optimize compensation values for volumetric positioning errors, enhancing spatial accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If geometric error compensation is performed by correcting CNC instructions, then machining accuracy is improved, but processing efficiency deteriorates due to the large number of CNC instruction lines (100,000+) for large and complex parts
Solution Approach 1:
The patent segments the volumetric positioning error into multiple geometric error components (12 specific geometric errors) that can be independently identified and compensated. By dividing the complex error correction task into manageable geometric error segments, the system achieves accurate compensation without requiring correction of every individual CNC instruction line, thus improving processing efficiency while maintaining machining accuracy.
2Measurement precision
If traditional geometric error identification methods are used, then compensation can be performed, but identification accuracy and tooling precision requirements become excessively high
Solution Approach 1:
The patent changes the measurement parameters by using a laser interferometer to directly measure volumetric positioning errors of the rotary axes instead of relying on traditional mechanical tooling. This parameter change from mechanical measurement to optical interferometry measurement reduces the precision requirements for physical tooling while achieving high identification accuracy through the superior resolution of laser interferometry.
3Ease of manufacture
If inspection tooling is added to identify geometric errors, then identification can be performed, but measurement precision deteriorates due to tooling errors affecting the identification results
Solution Approach 1:
The patent introduces a laser interferometer as an intermediary measurement device that directly measures the volumetric positioning errors of the rotary axes without requiring contact with the workpiece or traditional inspection tooling. This intermediary optical measurement system eliminates the propagation of tooling errors into the identification process, maintaining high measurement precision while enabling comprehensive geometric error identification.
Data Source
AI summary
Embodiments of the present disclosure provide a method of fast optimization and compensation for volumetric positioning errors of rotary axes of a five-axis CNC system machine tool. The method comprises: establishing a volumetric positioning error model; forming an error database containing 12 geometrical error vectors; constructing a volumetric positioning error compensation table; establishing a compensation value optimization model; completing an iterative optimization of compensation values of volumetric positioning errors; generating a volumetric positioning error compensation file for a CNC system to complete compensation for the volumetric positioning errors; and updating the error database, detecting linkage trajectories of the rotary axes, and setting a linkage trajectory positioning error threshold, and guaranteeing accuracy by iteratively implementing detection, optimization, and compensation.