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大多数快速原型制造系统采用 STL 文件作为与 CAD系统之间的数据交换接口。但是 ,STL 文件是通过用一系列的三角片逼近实际零件表面而产生的 ,STL 文件本身及其创建过程均存在许多问题。要提高模型的精度 ,就必须增加三角片的数量 ,同时减小三角片的尺寸。这必然造成 STL 文件庞大 ,后续处理时间较长 ,而且易产生缺陷 ,使后续处理不能进行。针对上述问题 ,本文分析了 STL文件的不足 ,提出一种 CAD系统与 RPM系统之间新的数据交换方法。该方法对 CAD系统中的真实模型直接切片 ,将切片后所得到的轮廓数据作为 CAD系统与快速原型制造系统之间的数据交换接口。该切片算法已在“超人 2 0 0 0 CAD/ CAM”系统中实现 ,算法表现稳定 相似文献
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针对3D打印中模型数据的截面轮廓求取问题,分析STL文件的计算机数据格式特征,提出面向STL文件的截面轮廓线段连接算法.首先,通过STL文件的相交面片选取与求交计算,直接生成相交截面的轮廓线段;然后,通过轮廓线段的连接判断,快速生成模型数据的截面轮廓;最后,借助PythonOCC的开源三维模型显示平台,使用Python的计算机编程语言编程开发面向STL文件的截面轮廓生成模块,并通过多个模型的数据测试对所提算法的有效性给予验证.实验结果表明,所提算法可完全避免模型数据的拓扑数据操作,并通过STL文件的直接数据处理,直接实现3D打印中模型数据截面轮廓的快速生成. 相似文献
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针对传统增材制造分层方法对复杂曲面类零件STL模型分层易造成部分层面轮廓线失真的问题,提出一种基于NURBS曲线的复杂曲面类零件分层截面轮廓生成算法。针对STL模型数据量大和分层速度慢的特点,采用了分组排序的求交算法进行分层,生成截面轮廓点云数据。以切平面与STL模型三角面片的交点作为NURBS曲线的型值点,设定型值点的权值,利用矩阵形式和切失边界条件确定了NURBS曲线的权因子,求解NURBS曲线的控制顶点,采用矩阵形式建立了各切片层的截面轮廓所对应的NURBS曲线方程,绘制了基于NURBS曲线的各层层面轮廓。采用基于NURBS曲线的复杂曲面类零件分层截面生成算法对燃气轮机中压缸动叶片和Ganesha模型进行了分层试验仿真和误差分析。进行了燃气轮机中压缸动叶片的打印试验,通过测量表明:采用本算法打印叶片的轮廓度偏差值符合要求,相比传统算法打印的叶片精度更高,从而验证了所提出的基于NURBS曲线的复杂曲面类零件分层截面生成算法的可行性和准确性。 相似文献
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为提高快速成型制造中STL模型切片轮廓的光滑性,提出了一种基于Loop模式的自适应曲面细分算法,首先分割出网格模型中的曲面和平面,对和尖锐边相邻的曲面三角面设计了特殊的细分规则.通过三角面顶点的平坦度和容差平坦度决定三角面是否做进一步细分,以达到自适应细分的目的.该算法在保留零件模型上尖锐特征的同时,提高了模型上曲面部分的光顺性,从而可以利用模型的全局信息获得光滑的2维切片数据. 相似文献
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STL文件修补算法研究 总被引:7,自引:0,他引:7
:STL文件在计算机辅助设计领域中得到广泛的应用 ,如快速原型制造系统与CAD系统之间的数据交换接口。但是 ,STL文件本身及其创建过程均存在许多问题 ,如裂缝、孔洞、覆盖等。这些缺陷会给后续处理带来许多不便。针对这个问题 ,本文提出了一种 STL文件的修补算法。该算法首先建立三角片之间的拓扑关系 ,然后检查三角片模型是否存在上述缺陷 ,如果存在 ,则对其进行修补。该算法已在“超人CAD/CAM”系统中实现 ,算法稳定可靠 ,且对上述缺陷 ,基本能正确有效地进行检测与修补 相似文献
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快速成型技术中的光斑半径补偿算法研究 总被引:1,自引:1,他引:0
光固化快速成型数据模型切片分层的结果是一系列封闭的多边形截面轮廓,由于光斑(或喷嘴)具有一定的尺寸大小,为了保证零件的制造精度,就需要对多边形截面轮廓进行补偿。为此,简化了补偿矢量计算方法,并针对两种尖角情况,提出了新的处理方法。对多边形轮廓补偿后可能出现的自相交现象,采用基于单调链的平面扫描算法,对自交点进行了求解,并提出了一种无效环的简单判别方法,提高了无效环的去除效率。通过无效环的去除,保证了补偿轮廓的正确性,提高了零件的制造精度。 相似文献
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Chung-Shing Wang Teng-Ruey Chang 《The International Journal of Advanced Manufacturing Technology》2008,37(7-8):770-781
The main objective of this research is to identify ways to simplify the STL meshes, while simultaneously maintaining the accuracy
of the STL file. It demonstrates a technique to simplify large and complex STL triangular meshes and to optimise STL shape
for rapid prototyping and manufacture. STL mesh re-triangulation can be separated into two processes, i.e., mesh deletion
and mesh rearrangement. In the mesh deletion process, two kinds of weighted-value ratio algorithms can be chosen for determining
the suitable value of STL mesh deletion. A genetic algorithm that incorporated fitness functions was used for the optimisation
of the rearranged STL meshes. Two case studies of STL mesh reconstruction, which examine the effects of the algorithms, are
presented. These studies show that optimisation of the shape of the STL file reduces its size, resulting in a reduction of
the fabrication time and improvement of the rapid prototyping process. 相似文献
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为满足CAD软件与快速成形领域的数据交换需要,提出了一种Parasolid数据的STL变换方法。利用Parasolid建模核心的PK-TOPOL-facet()函数将Parasolid模型按STL文件规则进行三角网格化,通过返回的拓扑信息构建三角面片与它的顶点和法向量的拓扑关系,并由此生成了STL文件。应用实例和Solidworks软件诊断表明,采用该方法可以将Parasolid文件变换为STL文件,生成的STL模型中无错误面和缝隙存在。 相似文献
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Generation of an STL File from 3D Measurement Data with User-Controlled Data Reduction 总被引:6,自引:0,他引:6
Y. H. Chen C. T. Ng Y. Z. Wang 《The International Journal of Advanced Manufacturing Technology》1999,15(2):127-131
Reverse engineering is a methodology for constructing com-puter- aided design (CAD) models of physical parts by digitising
an existing part, creating a computer model and then using it to manufacture the component. When a digitised part is to be
manufactured by means of rapid prototyping machines such as stereolithography apparatus (SLA) and selective laser sintering
equipment (SLS), etc., it is not necessary to construct the CAD model of a digitised part. This can be achieved by the proposed
novel method which can construct an STL file (the de facto file format for rapid prototyping machines) directly from digitised
part data. Furthermore, the STL file can be constructed with a significant data reduction at the users’ discretion. 相似文献
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L. Jie M. Jianhua H. Shuhuai 《The International Journal of Advanced Manufacturing Technology》2004,23(9-10):696-699
This paper introduces a new sheet metal dieless forming technology. This technology adopts the principle of “layered manufacture” in rapid prototyping technology; it can form sheet metal parts without dies. A new method of tool-path generation based on STL file for sheet metal dieless forming is proposed. 相似文献
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Improved intermediate point curve model for integrating reverse engineering and rapid prototyping 总被引:1,自引:1,他引:0
V. K. Kumbhar P. M. Pandey P. V. M. Rao 《The International Journal of Advanced Manufacturing Technology》2008,37(5-6):553-562
Direct integration of reverse engineering and rapid prototyping removes two intermediate steps of surface fitting from point
cloud data and STL file generation from CAD models. Therefore errors introduced due to surface fitting and triangulations
are eliminated and also the process of STL data validation and repair is avoided. Intermediate point based curve model (IPCM)
method is one of the promising approaches for direct integration of reverse engineering and rapid prototyping however this
approach has the limitation that it cannot handle objects, which result in multiple contoured slices. Moreover, IPCM based
method is implemented with layers of constant thickness slices, and adaptive slicing with this method is not attempted. The
present work is an attempt towards improving the capabilities of IPCM based method by overcoming the above-mentioned two limitations.
The new system developed here has been tested on many parts, which demonstrates the capability of the proposed system.
An erratum to this article can be found at 相似文献
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S.-H. Huang L.-C. Zhang M. Han 《The International Journal of Advanced Manufacturing Technology》2002,20(5):363-367
Although the STL (stereo lithography) file format is the de facto standard for the rapid prototyping industries, there are
always some defects in STL files, many of which are difficult to correct. Instead of correcting the defects of bad STL files
by a manual, interactive and complex approach with an STL file correction program, an error-tolerance slicing algorithm for
STL files is proposed in this paper. With the detailed analysis of complex defects such as cracks and non-manifold facets,
a complete topological structure for the facets model with defects is built and the layer is sliced effectively. The badly
sliced contour is processed by crack-tracking and non-manifold facet travelling methods to obtain a correct contour in a relatively
easy 2D way. 相似文献
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S.-H. Huang L.-C. Zhang M. Han 《The International Journal of Advanced Manufacturing Technology》2003,21(1):15-19
The STL file, which is de facto standard for the rapid prototyping industries, has too large a file size. This paper proposes
an improved interface between CAD and rapid prototyping systems, i.e. a CS (compressed STL) file that has very low data storage
redundancies and is completely compatible with the STL file. The CS file is about a quarter of the size of the original binary
STL file, without any model information loss. This is very suitable for file transferring via the Internet. Removing coordinate
data of duplicate vertices, bit-compression technology, and a comparison of the size and compressed performance of the STL
and the CS are also discussed.
ID="A1"Correspondance and offprint requests to: Dr Li-Chao Zhang, Rapid Prototyping Building, State Key Laboratory of Plastic Forming Simulation and Die and Mould Technology,
Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China. E-mail: elegantteac@yahoo.com 相似文献