Calibrating Rotary Apparatus on Coordinate Measuring Machine
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Solution Overview
Problem
The calibration of rotary apparatuses on coordinate measuring machines is a lengthy and inaccurate process due to changes in geometry and orientation over time, especially with multiple axes of rotation, requiring extensive measurement at various positions and being sensitive to temperature changes.
Innovation Solution
A position determining device connected to the base of the coordinate measuring machine is used to determine the relative position of the rotary apparatus, allowing for faster and more reliable calibration by positioning the apparatus within a specific spatial region, reducing the need for extensive probing and scanning of multiple surface points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods using multiple rotary positions and surface point probing are used, then measurement precision is improved, but calibration time increases significantly
Solution Approach 1:
The patent replaces the mechanical probing system with an optical measurement system. A laser scanner or camera captures the three-dimensional coordinates of calibration body surface points optically, eliminating the need for mechanical contact probing. This substitution dramatically reduces calibration time while maintaining measurement precision, as the optical system can capture multiple points simultaneously without the sequential mechanical movement and contact required by traditional methods.
Solution Approach 2:
The patent uses a calibration body with known three-dimensional coordinates that exceeds the minimum requirements for calibration. By providing more calibration points and more comprehensive geometric information than strictly necessary, the system achieves faster calibration through optical scanning while ensuring sufficient precision through the redundant measurement data.
2Measurement precision
If calibration is performed repeatedly to account for temperature changes and wear, then measurement precision is maintained, but productivity decreases
Solution Approach 1:
The optical calibration system performs comprehensive measurements much faster than mechanical probing, reducing the time penalty associated with repeated calibrations. Since temperature changes and wear effects can be compensated more frequently without significantly impacting productivity, the system can maintain high measurement precision through regular recalibration while minimizing downtime.
Solution Approach 2:
The patent performs calibration using a reference body with known coordinates before actual workpiece measurement. This preliminary calibration establishes accurate transformation parameters between the coordinate measuring machine's coordinate system and the workpiece coordinate system, ensuring measurement precision is maintained even when repeated calibrations are needed to account for environmental changes.
3Measurement precision
If multiple rotary positions are measured to capture geometry changes, then calibration accuracy is improved, but device complexity increases
Solution Approach 1:
The optical measurement system replaces complex mechanical positioning and probing mechanisms. Instead of requiring precise mechanical control of the probe at multiple rotary positions, the optical system (laser scanner or camera) captures the calibration body geometry non-contactly, simplifying the mechanical requirements while maintaining or improving measurement precision through the richness of optical data.
4Measurement precision
If tactile probing of multiple surface points is used, then calibration accuracy is improved, but the measurement system becomes more complex
Solution Approach 1:
The patent replaces the tactile probing system with an optical measurement system. Instead of using a mechanical probe to physically contact and measure surface points sequentially, the system uses a laser scanner or camera to optically capture the three-dimensional coordinates of calibration body surface points simultaneously. This substitution eliminates the complexity of mechanical probe positioning, contact force control, and sequential measurement coordination, while providing richer measurement data for improved calibration accuracy.
Data Source
AI summary
A method for calibrating a rotating device attached to a movable part of a coordinate measuring device having a first part secured to the movable part and a second part rotatable relative to the first part about an axis of rotation of the turning device, on which second part a measuring sensor for measuring workpieces can be attached. The rotating device or a body connected to the second part is moved to a local area of a position determining device by a drive system of the coordinate measuring device, which position measuring device is connected to the coordinate measuring device, by means of at least one sensor of the position determining device. A position of the rotating device or of the body connected to the second part is determined relative to the position determining device, and the rotating device is calibrated in accordance with the determined position.