Five-Axis Tool Path Correction for Surface Height Consistency
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Solution Overview
Problem
Existing methods for surface machining with five-axis machine tools, particularly those using end mills, face challenges in maintaining surface quality due to sudden changes in tool posture, deflection, center of rotation deviations, and acceleration/deceleration issues, leading to slight variations in the machined surface.
Innovation Solution
A method and device that set a target machining point on multiple tool paths, select machining points of interest, calculate and correct tool posture by averaging, and generate a new tool path to prevent interference between the workpiece and end mill, ensuring consistent tool orientation and reducing surface irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the tool posture is changed along a single tool path, then the surface machining can be performed, but the quality of the machined surface is reduced due to change in the amount of deflection of the tool, change in the center of rotation of the rotary feed axis, change in the curvature of the cutting edge, and change in the acceleration/deceleration of the rotary feed axes
Solution Approach 1:
The patent applies preliminary action by reading a predetermined number of blocks in advance as correction target program commands and performing tool direction command corrections before actual machining. This allows the system to pre-calculate and compensate for posture changes, deflection variations, and acceleration/deceleration effects that would otherwise degrade surface quality during machining operations.
Solution Approach 2:
The patent changes parameters by correcting tool direction commands to maintain a constant ratio between the movement amount of the linear shaft and the tool direction vector change amount for each block. This parameter adjustment compensates for variations in deflection, center of rotation position, cutting edge curvature, and rotary feed axis acceleration/deceleration, thereby maintaining machined surface quality.
2Manufacturing precision
If a plurality of blocks are read in advance for correction along a single tool path, then the tool posture can be corrected along that path, but the numerical controller cannot effectively correct the posture of the tool when the tool posture changes across a plurality of tool paths
Solution Approach 1:
The patent achieves universality by extending the tool direction command correction functionality to work across multiple tool paths simultaneously. The correction mechanism is designed to handle posture changes not only along a single tool path but also when transitioning between adjacent tool paths, making the numerical controller adaptable to complex multi-path machining operations while maintaining posture correction accuracy.
3Adaptability or versatility
If the tool posture changes between adjacent tool paths, then the machining can cover complex workpiece surfaces, but slight variations in height are formed on the machined surface due to tool holder interference, cutting force direction changes, and deflection amount changes
Solution Approach 1:
The patent applies feedback by continuously monitoring and correcting tool direction commands based on the relationship between linear shaft movement and tool direction vector changes. This feedback mechanism compensates for posture variations, tool holder interference, cutting force direction changes, and deflection amount variations that occur when machining complex workpiece surfaces across multiple tool paths, thereby maintaining consistent machined surface height.
Data Source
AI summary
The present invention sets a single machining point on a plurality of tool path rows, selects a machining point in a prescribed range with the point to be machined as the center, calculates the tool orientation at the point to be machined by way of averaging the tool orientation of the selected machining point of interest, corrects data pertaining to the tool orientation of the point to be machined by way of the calculated average tool orientation, acquires the shape data of a workpiece to be machined and the shape data of a ball end mill to be used, performs an interference check for the workpiece and the ball end mill on the basis of the corrected tool orientation data, and generates a new tool path on the basis of data pertaining to the corrected tool orientation when no interference between the workpiece and the ball end mill occurs.