Precise gouging-free tool orientations for 5-axis CNC machining

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 (HOC) [26,27], 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.

Iso-Planar Feed Vector-Fields-Based Streamline Tool Path Generation for Five-Axis Compound Surface Machining With Torus-End Cutters

“…In Ref. [46], the tool orientations, which tend to maintain the hyper-osculating configurations when it is accessible, and smoothly switch to nearly two-contact configurations if it is not accessible due to some constraints, are generated by a global optimization procedure for five-axis machining of freeform surfaces using a flat end cylindrical tool. As a result, a good approximation quality of machining can be obtained at a relatively high computation cost.…”

Towards efficient 5-axis flank CNC machining of free-form surfaces via fitting envelopes of surfaces of revolution

“…The idea is to adapt the milling tool, usually a torus or a cylinder, such that the contact circle possesses higher order contact with the surface. This technique is known as curvature matched machining, see [1,24,25,9,28,5] and other references cited in [28]. However, it is possible to consider non-traditional shapes of the milling tool [3,2] to approximate Φ by a smaller number of larger, geometrically simpler, but yet-sufficiently complex patches.…”

On initialization of milling paths for 5-axis flank CNC machining of free-form surfaces with general milling tools

“…In the context of flat end milling, this approach is known as curvature matching and the position of the tool is sought after such that the contact circle of the tool matches the curvature of the surface in a certain tangent direction. To increase the approximaition quality, one may require higher (third) order contact by considering cases where the contact circle becomes hyperosculating Wang et al [1993a,b], or to require double-tangential contact Kim et al [2015]. Even though the approximation quality is increased in all the above cases, conceptually the contact circle and the reference geometry share only finitely many contact points: infinitesimally close three -osculating, four -hyperosculating, or two pairs -double-tangential circles.…”