Multi-Axis Curve Interpolation with Rotary Axis Correction
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Solution Overview
Problem
Existing curve interpolating methods for numerical control machine tools often generate curves with widths larger than the tolerance width, leading to surface accuracy issues and vibration during machining, especially when dealing with multi-axis machines having both linear and rotary axes.
Innovation Solution
A method that calculates interpolation points and corrects command points for both linear and rotary axes separately, generating approximated curves to ensure the interpolated curve passes through the corrected points within the tolerance width, using a combination of geometrical command points and first-order derivative values to synthesize corrected command points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If curve interpolation is performed using commanded point sequence data, then the curve can be generated to pass through commanded points, but the generated curve width becomes larger than the tolerance width
Solution Approach 1:
The patent applies preliminary action by pre-calculating correction amounts for commanded points before generating the final interpolation curve. The system calculates correction amounts based on the distance from commanded points to the desired curve, then applies these corrections in advance to ensure the generated curve width remains within tolerance without exceeding it.
Solution Approach 2:
The patent changes parameters by introducing correction amounts that modify the original commanded point coordinates. The system adjusts the position parameters of commanded points by calculated correction values, transforming the original commanded sequence into a corrected sequence that ensures the interpolated curve stays within the specified tolerance width.
2Manufacturing precision
If commanded points are corrected to reduce curve width, then surface accuracy improves, but calculation complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the correction calculation into distinct stages: first calculating distances from commanded points to the desired curve, then computing correction amounts based on these distances, and finally applying corrections to generate the corrected commanded sequence. This segmented approach manages calculation complexity by breaking down the overall correction process into manageable steps.
Solution Approach 2:
The patent applies partial action by calculating correction amounts only when necessary - specifically when the distance from commanded points to the desired curve exceeds the tolerance width. The system performs partial corrections on selected commanded points rather than uniformly correcting all points, thereby reducing overall calculation complexity while maintaining surface accuracy.
3Ease of manufacture
If the curve passes through commanded points with calculation errors, then the interpolation is simple, but surface accuracy deteriorates and machine vibration occurs
Solution Approach 1:
The patent converts the harmful effect of commanded point calculation errors into a beneficial correction opportunity. By calculating distances from commanded points (including those with errors) to the desired curve and applying correction amounts, the system transforms erroneous commanded points into corrected points that improve surface accuracy and eliminate the cause of machine vibration.
Data Source
AI summary
A method of generating a smooth curve to perform interpolation from a commanded sequence of points by a numerical controller for a multi-axis machine tool having three linear axes and two or more rotary axes. Corrected command points are obtained for linear axes and for rotary axes. Components of corrected command points for linear axes and corrected command points for rotary axes are synthesized with each other so as to obtain a synthesized corrected command point. A curve passing through the synthesized corrected command points is generated to perform interpolation. As a result, a more appropriate curve interpolation method for a multi-axis machine tool having two or more rotary axes can be performed.