Angular Deviation Correction in Coordinate Measuring Machines
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Solution Overview
Problem
Coordinate measuring machines (CMMs) face significant challenges in accurately measuring workpieces due to angular deviations between movement axes, which are influenced by location, temperature, and loading mass, leading to errors in perpendicularity, radial, tangential, and axial deviations, especially in rotary tables where these deviations result in unacceptable tolerances.
Innovation Solution
A method to determine and correct angular deviations by assessing their location-dependent, temperature-dependent, and loading mass-dependent variations, using partial measurement regions and computational models to adjust the movement axes' alignment in real-time during measurement, allowing for precise coordinate measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional CMM guides are used to move measuring devices along perpendicular axes, then the structure is simple and easy to manufacture, but angular deviations occur between the axes leading to measurement errors
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting correction values based on the measured position of movable parts. The control method modifies the coordinate transformation parameters (angular deviation corrections) according to position-dependent, temperature-dependent, and mass-dependent variations, thereby compensating for guide inaccuracies without changing the physical guide structure.
Solution Approach 2:
The patent replaces mechanical precision guidance with a computational correction system. Instead of relying on perfectly manufactured mechanical guides, the system uses mathematical models and coordinate transformations to compensate for guide deviations, substituting mechanical precision requirements with computational processing.
2Measurement precision
If the CMM operates without real-time correction for angular deviations, then the operation is simple and fast, but measurement accuracy deteriorates due to location-dependent, temperature-dependent, and mass-dependent angular variations
Solution Approach 1:
The patent implements feedback by continuously monitoring the position of movable parts and using this information to dynamically adjust correction values. The control method measures the actual position, compares it with the ideal position, and applies real-time corrections based on the detected deviations in angular alignment caused by location, temperature, and mass variations.
Solution Approach 2:
The patent applies preliminary action by pre-determining correction values through calibration measurements at different positions, temperatures, and loading conditions. These correction values are stored and applied during actual measurement operations, preparing the system in advance for various operating conditions without requiring real-time complex calculations.
3Adaptability or versatility
If the CMM uses a rotary table for measuring workpieces, then the measurement capability is enhanced, but angular deviations cause unacceptable radial, tangential, and axial deviations
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting correction values based on the measured position of movable parts. The control method modifies the coordinate transformation parameters (angular deviation corrections) according to position-dependent, temperature-dependent, and mass-dependent variations, thereby compensating for guide inaccuracies without changing the physical guide structure.
Solution Approach 2:
The patent applies local quality by determining separate correction values for different partial measurement regions of the CMM. Instead of using a single global correction, the system identifies which partial region is currently being measured and applies the appropriate location-specific correction values, thereby optimizing measurement accuracy for each local area including the rotary table region.
Data Source
AI summary
A method for correcting an angular deviation between a real angle and an ideal angle between motion axes of a coordinate measuring device. The angular deviation depends on position, temperature, and/or loading mass. Values of a position-dependent angular deviation for partial measurement ranges of the coordinate measuring device are determined, and/or a difference between the angular deviation in a partial measurement range and a total measurement range, and the position-dependent angular deviation is corrected by using these values. Values of the temperature-dependent angular deviation for at least two different temperatures are determined and the deviation is corrected based on these. Values of the loading-mass-dependent angular deviation for loading the coordinate measuring device with at least two different loading masses are determined in a range of loading masses and/or information is obtained for correcting the loading-mass-dependent angular deviation in a temperature range and the deviation is corrected by using one of the values or information.