Five-Axis Tool Posture Control Using Mesh Contact Points
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Solution Overview
Problem
Existing machining control systems face difficulties in determining the posture of a tool with respect to a workpiece during five-axis machining, particularly when the workpiece is rotatable by two rotation axes, leading to challenges in accurately positioning the tool for effective machining.
Innovation Solution
A machining control device and method that acquires mesh data representing the workpiece's shape, calculates contact points for the tool, rotates the mesh data to align with the tool's movement, and determines the tool's posture by calculating relative angles based on distances between initial and secondary contact points, ensuring precise alignment and avoiding interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the workpiece is made rotatable by two rotation axes to increase machining freedom, then the degree of freedom of machining is improved, but the ability to determine the posture of the workpiece with respect to the tool deteriorates
Solution Approach 1:
The system performs preliminary calculation of the workpiece posture by computing the relative angle between the tool and workpiece before actual machining begins. The posture determination unit calculates the optimal posture based on mesh data and tool position in advance, allowing the control system to pre-determine the correct orientation of the rotatable workpiece for each machining position, thereby resolving the uncertainty caused by multiple rotation axes
Solution Approach 2:
The patent replaces direct mechanical measurement of workpiece posture with a computational approach. Instead of using physical sensors to detect the actual workpiece orientation during machining, the system substitutes this with mathematical calculations based on mesh data representation and geometric relationships, computing the relative angle between tool and workpiece through algorithmic determination of contact points and normal vectors
2Adaptability or versatility
If the tool and workpiece are relatively moved by five axes including two rotation axes, then the flexibility of machining operations is improved, but the complexity of determining tool posture with respect to the workpiece worsens
Solution Approach 1:
The system segments the complex five-axis posture determination problem into distinct computational steps: first representing the workpiece as mesh data, then calculating contact points between tool and workpiece, determining normal vectors at those contact points, and finally computing the relative angle from these segmented elements. This segmentation transforms an intractable complex problem into a series of manageable computational tasks
Solution Approach 2:
The patent introduces mesh data as an intermediary representation between the physical workpiece and the control system. Instead of directly processing complex five-axis coordinate transformations, the system uses mesh data (triangular surfaces representing the workpiece geometry) as an intermediate model to facilitate posture calculation. This intermediary abstraction simplifies the mathematical operations required for determining tool orientation
Data Source
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AI summary
A machining control device includes a posture determination unit configured to calculate, for each of the plurality of first contact points and while changing a relative angle of the tool with respect to the mesh data for respective predetermined angles, a second contact point where the tip of the tool and the mesh data come into contact when the tool is moved to the mesh data for each of the predetermined angles, and determine, as a posture of the tool, a relative angle of the tool with respect to the mesh data when the workpiece is machined, based on respective distances between each of the plurality of first contact points and a plurality of the second contact points each calculated for the predetermined angles.