Five-Axis Dual-Spline Feedrate Scheduling Under Axial Drive Constraints
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Solution Overview
Problem
Current feedrate scheduling methods for five-axis dual-spline interpolation face challenges in balancing machining quality and efficiency due to nonlinear relationships between tool-tip motion and joint axes motion, leading to motion waves and vibration, and are computationally intensive, limiting real-time capability.
Innovation Solution
A computational efficient feedrate scheduling method that disperses the toolpath by equal arc length, computes derivatives to determine feedrate-sensitive regions, and uses S-shape acceleration/deceleration mode to schedule constant speed in sensitive regions and smooth speed in non-sensitive regions, balancing motion stability and efficiency while reducing computational burden.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feedrate is increased to improve machining efficiency, then productivity increases, but motion wave and machining vibration occur degrading manufacturing precision
Solution Approach 1:
The patent implements dynamic feedrate adjustment by categorizing toolpath segments into feedrate-sensitive and feedrate-non-sensitive regions, then applying different speed profiles accordingly. This dynamic approach allows the system to optimize machining efficiency in non-sensitive regions while maintaining precision in sensitive regions, resolving the contradiction between productivity and manufacturing quality.
Solution Approach 2:
The patent applies local quality by treating different portions of the toolpath differently based on their sensitivity characteristics. Feedrate-sensitive regions receive constrained speed profiles to maintain precision, while feedrate-non-sensitive regions receive optimized speed profiles to maximize efficiency. This localized differentiation resolves the global contradiction between speed and quality.
2Manufacturing precision
If iterative computation is performed to satisfy drive constraints, then manufacturing precision is improved, but real-time capability is weakened due to heavy computational burden
Solution Approach 1:
The patent performs preliminary classification of toolpath segments into feedrate-sensitive and feedrate-non-sensitive regions before execution. This pre-processing step enables the system to pre-determine appropriate speed profiles for each segment, eliminating the need for heavy iterative computations during real-time execution while still satisfying drive constraints, thus resolving the contradiction between precision and real-time capability.
Solution Approach 2:
The patent segments the toolpath into distinct feedrate-sensitive and feedrate-non-sensitive regions, allowing different computational strategies to be applied to each segment. This segmentation reduces the overall computational burden by avoiding iterative computations in non-sensitive regions, thereby improving real-time capability while maintaining precision where needed.
3Productivity
If time-optimal feed speed is used to maximize efficiency, then productivity increases, but motion stability deteriorates causing frequent feedrate changes
Solution Approach 1:
The patent applies local quality by implementing constant speed profiles in feedrate-sensitive regions to ensure motion stability, while allowing optimized variable speed profiles in feedrate-non-sensitive regions to maximize efficiency. This localized differentiation resolves the contradiction between overall productivity and local motion stability.
Data Source
AI summary
This invention, a feedrate scheduling method for five-axis dual-spline curve interpolation, belongs to multi-axis NC (Numerical Control) machining filed, featured a feedrate scheduling method with constant speed at feedrate-sensitive regions under axial drive constraints for five-axis dual-spline interpolation. This method first discretizes the tool-tip spline with equal arc length, thus getting the relation between the axial motion and the toolpath by computing the first, second, and third order derivatives of the axial positions with respect to the tool-tip motion arc length. After that, determine the feedrate-sensitive regions with the constraints of axial drive limitations and the objective of balanced machining quality and efficiency. Finally, determine the acceleration/deceleration-start-point curve parameters by bi-directional scanning. The invented method can effectively make a balance between the feed motion stability and efficiency in five-axis machining, and possesses a high computational efficiency and a good real-time capability.