A Rapid Approach of Computing Multi-axis Tool Accessible Space for General Cutter Model by Utilizing Programmable Graphics Pipeline

Abstract

Computation of tool accessible space (TAS) is key to interference-free toolpath planning for multi-axis machining complex parts. However, most existing solutions are difficult to guarantee efficiency and accuracy simultaneously, and are only applicable to certain types of tools. Hence, this article proposes a rapid and accurate TAS computation approach for general cutters based on programmable graphics pipelines of modern graphics-processing unit (GPU). With this approach, a concept of MID (maximum interference distance)-space that quantitatively describes interference states between obstacles and a general cutter model is first proposed. Then, an MID model between obstacles and the general cutter model is presented. And a GPU-enhanced MID computing algorithm is developed based on new features of graphics pipelines. Moreover, an algorithm for batch computing TASs is presented based on GPU instancing. Experimental studies show that compared with traditional GPU-based methods, since our approach enables TASs computation of all cutter contact points to be completed in batches by running the graphics pipeline only once, the computation efficiency is improved by nearly 11 times. Besides, since the accuracy of our approach does not rely on the resolution of GPU rendered image, and also because the actual MID is identified precisely, the accuracy can be guaranteed very effectively. More encouragingly, our approach is general for various cutters, including special-shaped cutters, which greatly facilitate generating interference-free toolpath as well as optimizing tool postures globally for multi-axis machining complex parts.