Five-Axis Machine Tool Error Identification Using Sphere Calibrators
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Solution Overview
Problem
Existing methods for identifying geometric errors in five-axis-control machine tools are inaccurate due to the influence of single axis geometric errors and require manual operation, posing risks of collision and high costs.
Innovation Solution
A method involving a position measurement sensor tool and a calibrator with multiple spheres on the table, allowing automatic identification of inter-axis and single axis geometric errors by measuring center positions at various indexed angles, using reference angles to correct for positioning and straightness errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods for identifying geometric errors are used, then measurement can be performed, but the measurement accuracy is poor due to the influence of single axis geometric errors
Solution Approach 1:
The patent segments the measurement process into two distinct phases: first measuring single-axis geometric errors using a ball array, then measuring inter-axis geometric errors while compensating for the previously identified single-axis errors. This segmentation allows each measurement type to be handled with appropriate methods, improving overall measurement accuracy.
Solution Approach 2:
The patent performs preliminary measurement of single-axis geometric errors before measuring inter-axis geometric errors. By identifying and storing the single-axis error data first, the system can then use this information to compensate for errors during the subsequent inter-axis measurement, thereby improving the accuracy of the final geometric error identification.
2Ease of operation
If manual operation methods are used for geometric error identification, then measurement can be performed, but operator knowledge and skills are required and collision risks exist
Solution Approach 1:
The patent implements an automated measurement system where the control unit automatically controls the movement of the measurement probe and the rotation of the table without requiring manual operation. The system self-manages the measurement process, eliminating the need for operator skills and reducing collision risks through precise automated control.
Solution Approach 2:
The patent replaces manual mechanical operation with automated numerical control. The control unit uses programmed commands to automatically position the measurement probe and rotate the table, substituting human mechanical operations with automated electronic control, thereby eliminating collision risks associated with manual operation.
3Manufacturing precision
If geometric errors are not corrected, then machine operation is simple, but processing accuracy of workpiece deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the identified geometric errors (both single-axis and inter-axis) are stored and used to compensate for positioning errors during subsequent machining operations. The control unit automatically applies correction values based on the measured errors, improving workpiece accuracy without requiring complex manual intervention.
Solution Approach 2:
The patent creates a digital model of the geometric errors through measurement and stores this error data in the control unit. This error map or correction table is then used to compensate for positioning errors during machining, effectively copying the error pattern and applying reverse compensation to achieve accurate workpiece dimensions.
Data Source
AI summary
An error identification method for identifying an error includes: securing a calibrator having three or more spheres on the table; measuring an initial position of the calibrator with a position measurement sensor tool; calculating a reference angle of each of the rotation axes for positioning the calibrator to a predetermined reference position using a measured value in the measuring; indexing each of the rotation axes individually to a plurality of indexed angles with respect to the reference angle and measuring a center position of a sphere of the calibrator secured on the table at each of the indexed angles with the position measurement sensor tool; and identifying a positioning error and a straightness error of the linear axis, a squareness error between the respective linear axes, and a position error and an inclination error of each of the rotation axes based on a measured value in the indexing.