Rotary Device Error Correction via Multi-Position Measurement
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Solution Overview
Problem
Rotary devices in coordinate measuring machines and machine tools experience various error sources, leading to measurement and machining inaccuracies due to translational and rotational errors, which are compounded by workpiece position and alignment, requiring high calibration and maintenance efforts.
Innovation Solution
A method involving a coordinate measuring apparatus positioned at multiple circumferential positions around the rotary device's axis of rotation to measure the workpiece's surface extent, separating surface information from movement error information, allowing for the determination and correction of movement errors without extensive recalibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rotary device is used to rotate the workpiece during measurement or machining, then measurement time/machining time is shortened and productivity is increased, but measurement precision and manufacturing precision deteriorate due to rotational errors of the rotary device
Solution Approach 1:
The patent applies feedback by measuring the rotary device's rotational errors using a coordinate measuring machine at multiple circumferential positions, then using these measured error values to correct subsequent measurements. The system continuously monitors and compensates for rotational deviations, transforming the rotary device's errors into correctable data rather than irreducible measurement uncertainties.
Solution Approach 2:
The patent changes the parameter of measurement by taking measurements at multiple different circumferential positions around the rotary device's axis of rotation. By varying the circumferential position parameter and collecting error data from multiple angles, the system can separate and quantify different components of rotational error, enabling more effective correction than single-position measurements.
2Measurement precision
If high precision rotary devices are used to reduce measurement errors, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a coordinate measuring machine as an intermediary device to measure and characterize the rotary device's errors. Rather than requiring the rotary device itself to be perfectly precise, the system uses the CMM as a mediator to detect and quantify rotational deviations, then applies mathematical corrections. This transfers the precision requirement from the rotary device to the measurement and computation system.
Solution Approach 2:
The patent replaces mechanical precision requirements with computational correction. Instead of relying on mechanically perfect rotary bearings and alignment, the system uses measured error data and mathematical algorithms to compensate for mechanical imperfections. This substitutes complex mechanical precision requirements with simpler mechanical components plus computational processing.
3Measurement precision
If the rotary device is calibrated frequently to maintain precision, then measurement precision is improved, but loss of time and productivity decrease
Solution Approach 1:
The patent performs preliminary error measurement and characterization by taking measurements at multiple circumferential positions to establish the rotary device's error profile. This preliminary action creates a correction map that can be applied during normal operation, eliminating the need for frequent recalibration. The error characteristics are determined once and then reused for multiple workpieces and measurements.
Solution Approach 2:
The system enables the rotary device to essentially self-correct its errors by using the measured error data to compensate for its own rotational deviations. The error measurement and correction process is integrated into the normal measurement workflow, allowing the system to maintain precision without external calibration interventions. The rotary device's errors become self-characterized and self-corrected through the measurement and computation process.
Data Source
AI summary
A method for reducing errors in a rotating device permitting rotation of a workpiece about a rotational axis during the determination of co-ordinates or during the machining of the workpiece. The workpiece is rotated about the rotational axis and first and second measuring signals of a first and a second course of the workpiece surface are generated by the coordinate measuring device while the device is positioned at different first and second circumferential positions of the rotational axis. The first and the second measuring signals are used for separating redundant surface information and error information contained in the signals. The redundant surface information relates to the workpiece surface revolving around the rotational axis and the error information relates to errors in the rotating device resulting from deviations between actual positions and orientations of the rotational axis and corresponding ideal positions and orientations.