Ray-Based Swept Volume Analysis for Machining Simulation
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Solution Overview
Problem
Current methods for simulating NC milling are inefficient in accurately representing and rendering high-precision models of swept volumes, leading to discrepancies in the final shape of the workpiece, such as gouges or nicks, due to limited accuracy and high computational requirements, especially when dealing with complex tool paths and shapes.
Innovation Solution
The method involves populating the swept volume with a set of rays to determine the removed volume by analyzing intersections with the workpiece, using distance fields and ray-surface intersections to accurately model the removed volume and its geometric properties, allowing for high precision and efficient computation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional CSG subtraction operations are used to model removed volume, then the simulation can handle complex tool paths, but the computational complexity and time required increase significantly
Solution Approach 1:
The swept volume is segmented into a set of discrete rays that radiate from the tool center along the tool path. Instead of computing the entire volumetric intersection, the method divides the continuous volume into radial segments (rays), allowing parallel processing and reducing computational complexity while maintaining precision in determining the removed volume.
Solution Approach 2:
The patent introduces an intermediary representation called the 'swept volume' that acts as a mediator between the tool path and the workpiece geometry. This swept volume is populated with rays that serve as intermediaries to detect intersections with the workpiece surface, enabling accurate removed volume calculation without directly computing complex CSG operations.
2Measurement precision
If high precision models are used to detect micrometer-scale discrepancies, then the accuracy of surface defect detection improves, but the rendering time and computational resources increase
Solution Approach 1:
The method applies partial action by computing only the necessary portion of the swept volume intersections. Instead of rendering or computing the entire swept volume, the patent selectively evaluates rays that may intersect the workpiece, using distance field queries to quickly identify relevant intersections. This reduces computational effort while maintaining the precision needed to detect micrometer-scale surface defects.
Solution Approach 2:
The patent replaces traditional geometric intersection algorithms with a field-based approach using distance fields. Instead of mechanically computing polygon-polygon intersections, the method uses continuous distance field evaluations along ray paths, which allows for more efficient computation and easier implementation of high-precision intersection detection without the computational burden of traditional methods.
3Reliability
If manual testing with test workpieces is performed to verify NC machine instructions, then surface defects can be detected, but the process becomes time-consuming and expensive
Solution Approach 1:
The patent creates a virtual copy of the machining process through computer-based simulation. The simulated swept volume and ray intersections produce a digital representation of the removed volume and predicted surface geometry, allowing verification of NC machine instructions without physical test workpieces. This virtual copying enables rapid iteration and validation, improving reliability while eliminating the time and cost associated with manual testing.
Data Source
AI summary
A method simulates a machining of a workpiece by a tool. The method populates a swept volume representing a motion of the tool in relation to the workpiece with a set of rays, and determines a volume removed from the workpiece by the swept volume based on intersections of at least some rays with the workpiece. A model of the workpiece is modified based on the removed volume.