Error Map Preparation for CNC Machine Tool Positioning
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Solution Overview
Problem
Existing methods for correcting errors in machine tools with linear and rotational feed axes are inadequate, as they fail to accurately measure and correct position and attitude errors, particularly for tools with a linear feed axis and a rotational feed axis, and are not applicable to all types of machine tools.
Innovation Solution
A method and device for preparing an error map that measures and corrects position and attitude errors by setting lattice points in Cartesian coordinates, using a reference ball and non-contact sensors to determine position and attitude errors, and computing correction data to adjust the position command for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If deviation of the rotational axis is corrected using prior methods, then rotational feed axis positioning is improved, but errors varying depending on undulation of the rotational axis itself or position of the linear feed axis cannot be corrected
Solution Approach 1:
The patent transitions from measuring only rotational axis deviation to measuring tool tip position in three-dimensional space. By using a laser interferometer to measure X, Y, Z coordinates of the tool tip at multiple measurement points, the system captures errors in additional dimensions that vary with both rotational axis position and linear feed axis position, enabling comprehensive error correction.
Solution Approach 2:
The patent introduces a laser interferometer as an intermediary measurement device that directly measures tool tip position rather than inferring it from axis deviations. This intermediary measurement system provides accurate tool tip position data that accounts for all sources of error including rotational axis undulation and linear feed axis position errors.
2Adaptability or versatility
If error map is prepared for tool unit driven by parallel link mechanism, then tool unit error correction is improved, but method becomes inapplicable to machine tools with linear feed axis and rotational feed axis
Solution Approach 1:
The patent creates a universal error map preparation method that works for machine tools with both parallel link mechanisms and those with linear feed axes combined with rotational feed axes. By measuring tool tip position directly using laser interferometry and organizing errors in a standardized map format, the method becomes applicable to multiple machine tool architectures while maintaining correction accuracy.
3Device complexity
If only center position of reference ball is measured, then measurement process is simplified, but deviation of tool tip position due to posture error of main spindle cannot be corrected
Solution Approach 1:
The patent performs preliminary measurement of tool tip position at multiple predetermined measurement points before actual machining. By measuring at multiple points including different rotational axis positions and linear feed axis positions, the system预先 captures all relevant errors that will affect tool tip positioning during machining operations.
Solution Approach 2:
The patent uses measured tool tip position data to create an error map that provides feedback for correcting positioning commands. The measured errors from multiple measurement points are stored and used to generate correction values that are applied during actual machining to compensate for positioning deviations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-precision correction of position and attitude errors in machine tools with linear and rotational feed axes, ensuring accurate tool positioning and overcoming limitations of previous methods.
Implementation Method 1
a laser interferometer to measure a position of a tool tip
Data Source
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AI summary
In a numerically controlled machine tool which has a linear feed axis (X,Y,Z) and a rotational feed axis (A,B,C) and in which a main spindle (4) and a table (6) are movable relative to each other, a position error (34a) and an attitude error (34b) produced by an operation of a linear feed axis (X,Y,Z) and a rotational feed axis (A,B,C) are measured at a plurality of measurement points set within a movable range of the linear feed axis (X,Y,Z) and the rotational feed axis (A,B,C), and the position error (34a) and the attitude error (34b) thus measured are stored as an error map in correspondence to a position of the linear feed axis (X,Y,Z) and a rotation angle of the rotational feed axis (A,B,C).