【作者】 张永；

【导师】 周天瑞；

【作者基本信息】 南昌大学 ， 材料加工工程， 2008， 硕士

【摘要】 快速成形技术是20世纪80年代中后期发展起来的、观念全新的现代制造技术,它能以最快的速度将设计思想物化为具有一定结构和功能的三维实体,低成本制作产品原型甚至零件,非常适合当代市场竞争的需要。而对于其中的光固化(SLA)和熔融沉积(FDM)快速成形工艺,支撑结构的产生是一项必不可少的工艺规程,支撑结构在固定零件、保持零件形状、减少翘曲变形方面有着重要作用。为了开发出拥有自主知识产权的熔融沉积快速成形系统,本论文展开了支撑智能化设计研究工作。首先,支撑数量的多少直接影响到零件与支撑相接触面的表面质量、增加加工废料和去除的难度,针对此问题本文进行了分层方向优化,减少了支撑生成数量;基于STL模型分层后的层片文件,论文采用了先填充后比较的支撑设计方法将复杂的轮廓环布尔运算转化为二维线段的逻辑比较运算,提高了支撑生成效率;为优化扫描路径、缩短零件制造周期,对生成的支撑线段进行了分区域规划和标准CLI格式输出;最后以Visual C++为编程语言、OpenGL为图形工具,开发了一个支撑自动生成的可视化软件,并将该软件模拟产生的CLI格式零件在快速成型机上进行了生产实验,实验结果表明:文中支撑结构自动生成方案正确、可靠、实用,具备投入实际生产的经济价值。同时在本文的工作中,还在以下方面加入了新的设计方法和思想:首先,将分层方向优化物化为三个直接的数学模型指标,通过零件的可视化将经验优选与目标定量计算相结合。对于特定的成型物件,根据制作者对各指标的侧重程度(即既权重系数)就可以选择相应的最佳制作方向,简便实用。其次,将各层面轮廓填充转化为二维线段后,在进行上下层面二维线段的求差、并运算时不是直接进行各端点坐标浮点数的逻辑判断比较,而是对各点进行合并排序并附加状态标志,然后根据一条线段中首末两点的状态位就可直接实现该线段的去除或保留,大大简化了逻辑判断的复杂程度。最后,基于层片扫描线比较产生的各层支撑线均为同一方向,为实现上下两层支撑线的十字交叉填充、增加支撑强度,本文提出了层片分别沿水平和垂直方向填充、进行两次支撑运算,然后奇数层输出相应的水平支撑线、偶数层输出相应的垂直支撑线,即实现了隔层交叉填充。更多还原

【Abstract】 Rapid prototyping and manufacturing (RP&M), a totally new fabricating technology developed in the end of 1980s, can transform design thoughts into 3D parts with certain structure and function in rapid speed and at cheap cost, so it satisfies modern competition greatly. But for the SLA and FDM process of RP, support which plays a important role in fixing part and keeping shape、decrease deformation of the part is a indispensable structure. In order to explore self-owning RP system, research on support design was done in the thesis.Above all, the quantity of support affected the surface finish of part and increased the difficulties to wipe off extra material, according to that, optimization for the fabrication orientation was done firstly; secondly, to get the support lines, the way that filling slices of parts to produce scan lines and then comparing and evaluating them was used, which transformed complicated Boolean count into simple compare of lines, had improved efficiency of support production dramatically; thirdly, zoning was done to the support lines to optimize their scan path and shorten manufacturing circle, then perfect scan path data was exported in CLI; at last, with the help of C++ and OpenGL, all the arithmetic was realized and a view software to produce support automatically was worked out, the CLI files produced by the software were used to make experiment in RP machine, and experiment results showed that: method to produce support in this passage was right、reliable and practical, had economic value to be used in factory. Moreover, within all the work in the thesis, the following designing methods were new and original.First, three mathematic models were proposed when dealing with the optimization of fabricating orientation, through the view of the STL parts, experience and rational evaluation were combined to choose the best slicing direction. For a certain part, if the producer had given coefficients, the perfect orientation could be decided easily.Second, after the slices were filled to transformed into lines, a new compare way that adding signs to points to decide the keeping or wiping of lines was used to take place of direct compare of lines ’points, which decreased the difficulties of logic compare greatly.Third, the support lines of different slices got by the scan lines’ compare were in same direction, but to increase support strength, crossing support lines every two slices were needed. To solve the problem, way of filling slices in horizontal and vertical direction separately, and then calculating support lines twice according to scan lines of different direction was taken, in this way, the crossing support was realized.更多还原