Machine Tool Motion Error Compensation via Squareness Correction
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Solution Overview
Problem
Existing methods for measuring and compensating motion errors in machine tools require specialized instruments, which are costly and prone to inaccuracies due to angular deviations affecting squareness measurements, leading to inconsistent workpiece quality.
Innovation Solution
A method using a square calibration master with known measurement surfaces and a position measurement sensor to calculate compensation parameters without specialized instruments, by measuring and comparing squareness differences and angular deviations, adjusting for errors based on threshold values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If specialized measuring instruments are used to measure motion errors, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses a laser interferometer to create optical copies/images of the workpiece and measurement surfaces, allowing virtual measurement without physical contact with specialized tactile instruments. The laser beam creates light patterns that represent the geometry being measured, enabling precise motion error measurement through optical field copying rather than mechanical contact.
Solution Approach 2:
The patent replaces traditional mechanical measuring instruments (such as tactile probes, dial indicators, and precision gauges) with a laser-based optical measurement system. The laser interferometer uses light waves instead of mechanical contact to detect positions and calculate motion errors, eliminating the need for complex mechanical measurement chains and reducing device complexity.
2Ease of operation
If angular deviation is not compensated, then measurement process is simpler, but measurement precision deteriorates due to angular deviation affecting squareness
Solution Approach 1:
The patent implements a feedback mechanism where the laser interferometer continuously monitors the actual positions of the workpiece and measurement surfaces, calculates angular deviations from expected positions, and uses this information to compensate for errors in real-time. The system measures the actual motion errors including angular components and feeds this data back to correct the squareness calculation, ensuring accurate results even when angular deviations are present.
3Manufacturing precision
If compensation parameter calculation includes angular deviation correction, then manufacturing precision is improved, but calculation complexity increases
Solution Approach 1:
The patent performs preliminary measurements of the workpiece and measurement surfaces using the laser interferometer before final compensation parameter calculation. The system pre-calculates angular deviations and position errors from these initial measurements, storing them for use in the subsequent compensation parameter calculation. This preliminary action separates the measurement phase from the calculation phase, making the overall process more manageable despite the complexity of the compensation algorithms.
Data Source
AI summary
A method includes: installing a square calibration master on a table, and measuring each of measurement surfaces A, B, and C of the square calibration master by a position measurement sensor attached to a main spindle; calculating a first squareness between the measurement surfaces A and B; calculating a second squareness between the measurement surfaces A and C; calculating a difference between the first squareness and the second squareness; comparing the difference with a preliminarily set difference threshold value; calculating an average value of the first squareness and the second squareness when the difference is equal to or less than the difference threshold value, and calculating a corrected squareness based on an angular deviation and the first squareness or the second squareness when the difference exceeds the difference threshold value; and setting the compensation parameter based on the average value or the corrected squareness.