A new continuous printing path planning method for gradient honeycomb infill structures

Cellular infill structures such as honeycomb have been widely used in the field of light weighting. In recent years, the emergence of additive manufacturing technologies has provided a new solution to fabricate complicated cellular infill structures. This paper presents a continuous printing path planning method for gradient honeycomb structures. Given a 2D filling region represented by a polygon, a honeycomb graph that covers the filling area is trimmed to generate an infill pattern. Then an algorithm is proposed to transform the honeycomb filling pattern into an Eulerian graph, which can be traversed by a single-stroke printing path. For each honeycomb, double-spiral paths are used to generate gradient honeycomb structures with varying wall thicknesses. Later, the 2D honeycomb infills are generalized to 3D cases that are suitable for multi-axis printing. First, three mutually orthogonal vector fields that are embedded on the tetrahedral mesh of the printed part are generated by considering the support-free condition. Then the three vector fields are used to calculate three monotonically increasing scalar distance fields, which span a non-Euclidean space. Finally, the 2D honeycomb infills are generated in the non-Euclidean space with parallel sliced layers, which are then mapped back to the Euclidean space to obtain the real self-supporting 3D honeycomb infills. The proposed 2D/3D honeycomb infill structures generation algorithms have been verified by both simulation and experimental tests.