NC Turntable Geometric Error Measurement Using Four-Station Laser Tracing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for measuring geometric errors in numerical control turntables, such as laser interferometer and ballbar methods, suffer from low efficiency and accuracy, particularly in high-end precision applications like large-aperture optical components, due to dependency on operator skills and lengthy adjustment processes.
Innovation Solution
A measurement method utilizing a four-station laser tracer system, which establishes a self-calibration coordinate system, calibrates positions using non-linear least squares, and separates geometric errors through spatial position analysis, enabling fast and precise detection by rotating the turntable at specific angular intervals and converting between coordinate systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser interferometer measurement method is used, then positioning errors of turntable can be measured, but optical path adjustment is difficult and measurement efficiency is low
Solution Approach 1:
The patent replaces the traditional mechanical/optical interferometer measurement system with a laser tracker system that uses laser ranging technology. This substitution eliminates the complex optical path adjustment requirements while maintaining measurement precision, thereby improving measurement efficiency significantly.
Solution Approach 2:
The patent changes the measurement parameters from interferometric fringe counting to direct laser time-of-flight or phase-based distance measurement. This parameter change simplifies the measurement process and eliminates the need for delicate optical path alignment, resolving the contradiction between precision and efficiency.
2Measurement precision
If ballbar measurement method is used, then geometric errors can be measured, but multiple installations are required and adjustment takes a lot of time
Solution Approach 1:
The patent implements a universal measurement system using laser tracker that can measure multiple geometric errors (roundness, runout, axial/runout errors, pitch errors, yaw errors, and tilt errors) with a single installation configuration. This eliminates the need for multiple ballbar installations and adjustments, significantly reducing time loss while maintaining measurement precision.
Solution Approach 2:
The measurement system automatically performs error separation and calculation through integrated software algorithms, eliminating the manual adjustment and calculation processes required by ballbar methods. The system self-calibrates and processes measurements without requiring operator intervention for eccentricity adjustment, reducing time loss substantially.
3Measurement precision
If ballbar measurement method is used, then geometric errors can be separated, but test range is relatively small and measurement accuracy is limited
Solution Approach 1:
The patent transitions from the limited one-dimensional ballbar measurement approach to three-dimensional laser tracker measurement. By measuring target sphere positions in 3D space and rotating the turntable, the system can determine multiple geometric errors simultaneously with much larger measurement ranges and higher accuracy through spatial coordinate analysis.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves high accuracy and fast detection of geometric errors, suitable for precise numerical control machine tools, reducing measurement uncertainty and time, and is applicable to both single and multi-axis turntables without relying on machine tool coordinate systems.
Implementation Method 1
a self-calibration coordinate system of the laser tracer interferometers is established... calibration of position parameters of the laser tracer interferometers is performed... coordinates of the points are measured
Data Source
AI summary
A method for measuring geometric errors of a numerical control turntable based on a four-station laser tracer system includes: establishing a self-calibration coordinate system and calibrating positions of tracking interferometers; respectively placing each of target lenses at three non-coplanar points that are above the numerical control turntable and keep certain distances from the numerical control turntable, controlling the numerical control turntable to rotate at a certain angular interval θj, and based on positions of the tracking interferometers being known after calibration, solving coordinates of each of measurement points in the self-calibration coordinate system using a non-linear least square method; establishing a turntable coordinate system; perform a conversion between the turntable coordinate system and the self-calibration coordinate system; separating six geometric errors of the numerical control turntable using spatial position errors of the three points at a same position and using the linear least squares method.