Abstract
We present a precise approach to the generation of optimized collision-free and gouging-free tool paths for 5-axis CNC machining of freeform NURBS surfaces using flat-end and rounded-end (bull nose) tools having cylindrical shank. To achieve high approximation quality, we employ analysis of hyper-osculating circles (HOCs) (Wang et al., 1993a,b), that have third order contact with the target surface, and lead to a locally collision-free configuration between the tool and the target surface. At locations where an HOC is not possible, we aim at a double tangential contact among the tool and the target surface, and use it as a bridge between the feasible HOC tool paths. We formulate all such possible two-contact configurations as systems of algebraic constraints and solve them. For all feasible HOCs and two-contact configurations, we perform a global optimization to find the tool path that maximizes the approximation quality of the machining, while being gouge-free and possibly satisfying constraints on the tool tilt and the tool acceleration. We demonstrate the effectiveness of our approach via several experimental results.
•We present an algorithm for generating optimized gouging-free tool path for 5-Axis CNC machining.•We employ analysis of hyper-osculating circles that provides third order approximation of the surface.•Double tangential contact between the tool and the target surface is employed to connect feasible hyper-osculating tool paths.•A robust collision and gouging detection algorithm is provided.•We introduce a global optimization algorithm that maximizes the geometric matching between the tool and the target surface.