THESIS
2022
1 online resource (viii, 136 pages) : illustrations (chiefly color)
Abstract
Process planning for multi-axis additive manufacturing (AM) is a long-standing topic in this area starting with the compliance with printing requirement. A typical process planning is formed by various steps containing model partitioning and packing, printing orientation, support structures, slicing method, print path planning generation, and post processing, etc. For realizing support-free AM, researchers in this area mainly focus on the optimization of model topology, fabricating orientation, slicing layer generation and collision avoidance. In this work, we combine model decomposition with multi-axis motion planning for AM without any support material.
First, we present a skeleton-based process planning framework for automatically generating a multi-axis support-free printing path fo...[
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Process planning for multi-axis additive manufacturing (AM) is a long-standing topic in this area starting with the compliance with printing requirement. A typical process planning is formed by various steps containing model partitioning and packing, printing orientation, support structures, slicing method, print path planning generation, and post processing, etc. For realizing support-free AM, researchers in this area mainly focus on the optimization of model topology, fabricating orientation, slicing layer generation and collision avoidance. In this work, we combine model decomposition with multi-axis motion planning for AM without any support material.
First, we present a skeleton-based process planning framework for automatically generating a multi-axis support-free printing path for continuous 3+2-axis AM of an arbitrary freeform part. The framework is based on the geometric processing of skeletonization and decomposition and is particularly suitable for a part with distinct multiple trunk-branch structures. The physical printing experimental results carried out by the authors indicate that the proposed framework has performed well and fabricated some challenging models with large overhangs and twisty spatial topologies.
Next, we present a voxel-based process planning for realizing complex model in an overlap-free decomposition and support-free 3-axis orthogonal printing along at most five axis-aligned build directions. Firstly, we utilize voxelization algorithm to discretize the input surface mesh into voxelated model. Then, by introducing the metric of support-free assessment, a series of layers are generated with respect to a growing field that extracts an axis-aligned support-free volume. Next, by introducing collision check and overlap avoidance constraints, previous support-free volume is converted into independent volume which possesses collision-free and overlap-free characteristic and can be fabricated individually. Finally, iso-contour print path is planned in terms of the growing field and barycenter directly. The results show that models with large overhangs are decomposed into independent volumes with print paths effectively by our approach. Our proposed algorithm is validated on physical experiments by our homemade printing system. This technique is fully relied on the prerequisite which limits the printing direction alongside axis-alignment. It would be useful and helpful for conducting support-free printing with slightly modified traditional 2.5D printer and reduce the dependence on the cost of advanced hardware.
Last, we present a heat field based curved layer volume decomposition method for 5-axis support-free printing. Given a tetrahedral mesh of a solid model to be printed, we first establish a geodesic distance field embedded on the mesh, whose value at any vertex is the geodesic distance to the bottom of the model. Then the model can be naturally decomposed into curved layers by interpolating a finite number of iso-geodesic distance contours. The proposed method is robust and high-efficient, whose time complexity is relatively low. Additionally, the interpolated contours morph from bottom-up in an intrinsic and smooth way due to the nature of geodesics, which will be very friendly to multi-axis printing. To improve printing efficiency, we also propose a printing sequence optimization algorithm that can effectively reduce the air-move path length. Ample experiments in both computer simulation and physical printing are performed, and the experimental results convincingly confirm the advantages of our method.
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