In additive manufacturing, infill structures are commonly used to reduce the weight and cost of a solid part. Currently, most infill structure generation methods are based on the conventional 2.5-axis printing configuration, which, although able to satisfy the self-supporting condition on the infills, suffer from the well-known stair-case effect on the finished surface and the need of extensive support for overhang features. In this paper, based on the emerging continuous multi-axis printing configuration, we present a new lattice infill structure generation algorithm, which is able to achieve both the self-supporting condition for the infills and the support-free requirement at the boundary surface of the part. The algorithm critically relies on the use of three mutually orthogonal geodesic distance fields that are embedded in the tetrahedral mesh of the solid model. The intersection between the iso-geodesic distance surfaces of these three geodesic distance fields naturally forms the desired lattice of infill structure, while the density of the infills can be conveniently controlled by adjusting the iso-values. The lattice infill pattern in each curved slicing layer is trimmed to conform to an Eulerian graph so to generate a continuous printing path, which can effectively reduce the nozzle retractions during the printing process. In addition, to cater to the collision-free requirement and to improve the printing efficiency, we also propose a printing sequence optimization algorithm for determining a collision-free order of printing of the connected lattice infills, which seeks to reduce the air-move length of the nozzle. Ample experiments in both computer simulation and physical printing are performed, and the results give a preliminary confirmation of the advantages of our methodology.

中文翻译：

---

具有晶格填充结构的自由形状零件的多轴无支撑打印

在增材制造中，填充结构通常用于减轻实体零件的重量和成本。目前，大多数填充结构生成方法基于传统的 2.5 轴打印配置，虽然能够满足填充的自支撑条件，但存在众所周知的成品表面阶梯效应和需要对悬垂特征的广泛支持。在本文中，基于新兴的连续多轴打印配置，我们提出了一种新的晶格填充结构生成算法，该算法能够同时实现填充的自支撑条件和边界面的无支撑要求。那个部分。该算法严重依赖于嵌入实体模型的四面体网格中的三个相互正交的测地距离场的使用。这三个测地距离场的等测地距离面之间的交点自然形成了所需的填充结构格子，而填充的密度可以通过调整等值方便地控制。将每个弯曲切片层中的点阵填充图案修整成符合欧拉图，从而产生连续的打印路径，可有效减少打印过程中的喷嘴回缩。此外，为了满足无碰撞要求，提高打印效率，我们还提出了一种打印序列优化算法，用于确定连接点阵填充的无碰撞打印顺序，旨在减少喷嘴的空气移动长度。在计算机模拟和物理打印中进行了大量实验，结果初步证实了我们方法的优势。