CMM Inspection Gauge Calibration via Multi-Posture Measurement
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Solution Overview
Problem
The calibration of inspection gauges for coordinate measuring machines (CMMs) is complex and time-consuming, requiring the measurement of all ball-to-ball distances using a reference instrument like an optical interferometer.
Innovation Solution
A calibration method that involves installing the inspection gauge in multiple postures on a CMM, measuring ball-to-ball distances in each posture, and calculating calibration values by solving simultaneous equations, reducing the need for extensive reference instrument setup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all ball-to-ball distances of the inspection gauge are measured using a reference instrument, then calibration accuracy is improved, but calibration time and complexity increase significantly
Solution Approach 1:
The calibration process is segmented into multiple measurement postures (first posture, second posture, third posture) where different edges of the inspection gauge are measured in each posture. This segmentation allows the calibration to be performed through multiple partial measurements rather than requiring all measurements to be taken simultaneously with the reference instrument, thereby reducing calibration time while maintaining accuracy through mathematical reconstruction of all ball-to-ball distances.
Solution Approach 2:
The patent introduces a new dimension of measurement by utilizing multiple spatial postures of the inspection gauge. Instead of measuring all distances in a single configuration, the gauge is rotated to different postures (first rotational symmetry axis, second rotational symmetry axis) to bring different edges into the measurement position. This dimensional approach allows the CMM to measure distances that would otherwise require complex reference instrument setup.
2Measurement precision
If all ball-to-ball distances are measured using a reference instrument, then complete calibration data is obtained, but the calibration process becomes complex and difficult to operate
Solution Approach 1:
The inspection gauge serves itself for calibration by utilizing its own geometric symmetry. The gauge is rotated to different postures and the CMM measures distances in these configurations. The mathematical processing then reconstructs complete calibration data from these partial measurements, eliminating the need for complex reference instrument setup and operation while maintaining calibration completeness.
Solution Approach 2:
The patent replaces the mechanical complexity of reference instrument setup with an automated measurement system. Instead of manually positioning and measuring all ball-to-ball distances with a reference instrument, the CMM automatically measures distances in multiple postures, and mathematical processing (solving simultaneous equations) substitutes for the complex mechanical alignment and measurement procedures.
3Productivity
If multiple measurement postures are used with CMM, then calibration time is reduced, but measurement error identification becomes more complex
Solution Approach 1:
The patent performs preliminary identification of measurement errors at specific measurement positions before the actual calibration measurements are taken. By pre-identifying and characterizing the measurement errors at each posture, the subsequent calibration process can account for these errors systematically through mathematical processing, rather than dealing with uncharacterized errors that would complicate the analysis.
Data Source
AI summary
A calibration method includes: measuring, with a CMM, a ball-to-ball distance of a plurality of edges of an inspection gauge installed in a first posture, a second posture and a third posture, and calculating a calibration value calibrating a ball-to-ball distance between two balls at respective ends of a plurality of edges of the inspection gauge by solving simultaneous equations including the ball-to-ball distance of the plurality of edges of the inspection gauge installed in the first posture, the ball-to-ball distance of the plurality of edges of the inspection gauge installed in the second posture, the ball-to-ball distance of the plurality of edges of the inspection gauge installed in the third posture, and a measurement error of the CMM at the measurement position.