Profile Measuring Instrument Runout Error Correction
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Solution Overview
Problem
Profile measuring instruments face measurement errors due to runout of the rotary table and squareness issues, which degrade measurement accuracy as the measurement position moves away from the origin of the table coordinate system.
Innovation Solution
Incorporating a reference gauge measuring part and a correction function generating part to calculate and apply a correction function based on the difference between measured and known diameters or radii, transforming measurement values between coordinate systems to correct for runout and squareness errors, thereby improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If coordinate systems are set at predetermined positions for measuring workpiece profiles, then measurement process is simplified, but measurement errors increase due to rotary table runout and instrument squareness
Solution Approach 1:
The invention performs preliminary measurement of a reference gauge (cylinder or sphere) before measuring the workpiece to detect systematic errors. By measuring the reference gauge with known dimensions at the same position and orientation as the workpiece, the system pre-calculates correction values for runout and squareness errors, which are then applied during actual workpiece measurement to improve accuracy
Solution Approach 2:
The system uses the measured deviation between the actual reference gauge dimensions and their known nominal values as feedback to generate correction functions. These correction functions are stored and automatically applied during workpiece measurement, creating a closed-loop error compensation mechanism that maintains high precision without complicating the measurement workflow
2Adaptability or versatility
If measurement position is spaced apart from the origin of the table coordinate system, then measurement range is expanded, but measurement errors are increased due to runout and squareness
Solution Approach 1:
The invention introduces a reference gauge as an intermediary object between the measurement system and the workpiece. By measuring the reference gauge at the same distant position where the workpiece will be measured, the system captures position-specific errors (runout and squareness) that vary with distance from the origin. The correction functions derived from this intermediary measurement enable accurate workpiece measurement at any position within the expanded measurement range
Data Source
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AI summary
A coordinate measuring machine (1) includes: a reference gauge measuring part (51) for measuring a diameter or radius of a reference gauge along an axial direction in a reference gauge coordinate system set for the reference gauge having a known diameter or radius; a correction function generating part (52) for generating a correction function based on a difference between the diameter or radius of the reference gauge measured by the reference gauge measuring part (51) and the known diameter or radius and a measuring point of the reference gauge measuring part (51); a measuring part (53) for measuring a workpiece in a workpiece coordinate system set for the workpiece; a first transformer (54) for transforming a measurement value measured by the measuring part (53) in the workpiece coordinate system into the reference gauge coordinate system; a corrector (55) for correcting the measurement value transformed into the reference gauge coordinate system by the first transformer by a correction function generated by the correction function generating part (52); and a second transformer (56) for transforming the measurement value corrected by the corrector (55) in the reference gauge coordinate system into the workpiece coordinate system.