Multi-Resolution Cutting Force Prediction Using a Quad-Tree Decomposition for Cutter/Workpiece Engagements

Virtual Machining (VM) is the use of computers to simulate the physics of machining processes. It can be used to effectively identify problems in machining complicated workpieces and in optimizing processes. At the heart of VM is the ability to predict the cutting forces generated as the tool generates chips at the tool workpiece interface. For these predictions to be realistic two things are necessary. First, accurate representations of how the cutter engages the workpiece need to be generated along each toolpath under consideration. This is referred to as the Cutter/Workpiece Engagement (CWE). Second, a force model is needed that integrates the contribution from each element within the CWE. In this paper a new technique for integrating the force contributions is presented. It utilizes a Quad-Tree representation for the CWE. This representation provides several advantages over other approaches for integrating the force contributions. Amongst these is the ability to represent the aggregated force at different resolutions. This has the potential to reduce the time required to perform a simulation by scanning a tool path at a lower resolution to bound intervals where heavy engagements are encountered. These intervals can then be analyzed at a higher resolution for greater accuracy. Examples are presented using CWEs extracted for 2 1/2D milling operations from a component modeled on a leading CAD/CAM system.