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目前,熔融沉积成型技术中提出了各种自适应分层算法来改善成型效率和成型精度无法兼顾的缺点。其中,基于STL模型三角面片法向量的自适应分层算法存在以下问题:如果三角面片法向量与分层方向间的夹角过大或过小,这一算法无法实现层厚随着法向量与分层方向之间夹角的变化而自适应变化。为此,本文应用归一化的方法对其进行改进,将模型等厚分层后再根据归一化的原理确定每一层的自适应层厚值;其次基于MATLAB对这一自适应分层算法及其改进算法进行仿真;最后在熔融沉积实验平台上对其进行实验验证。实验结果表明,相对于原始算法,改进算法的自适应分层效果显著提高,且零件成型效率上升了22%,成型精度上升了29%,切实有效。 相似文献
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在快速成型领域,一般分层算法不考虑模型特征,这可能会导致一些重要特征的丢失或偏移。针对此问题,在充分研究现有分层算法的基础上,提出一种保留模型特征的分层算法。该分层算法首先对STL模型三角面片进行预处理排序,然后以自适应分层算法确定分层厚度,最后对特征进行识别,针对不同特征进行不同处理来调整分层厚度,使分层厚度考虑到加工层厚引起的误差,从而可以保证成型件特征位置的准确。通过实验验证,该分层算法可以精确地识别特征,合理地确定分层厚度,具有一定的参考价值。 相似文献
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快速成形容错切片中线段集合自适应连接方法 总被引:1,自引:0,他引:1
阐述了一种基于STL文件容错分层边界线段自适应连接的有效方法,将自适应方法应用于快速成形数据处理过程中,恰当地选择自适应变量、评价参数和约束条件,并进行数学公式推导。应用该方法实现了STL文件层面边界线的自适应连接。该方法比STL文件纠错方法减少了计算量和人工操作时间;与已有的裂缝跟踪方法相比,对于交叉情况,通过设不可连接端点的方法避免了全部拆分重新连接,提高了计算速度。该方法已在开发的数据处理软件中得到应用,运行情况良好。 相似文献
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为克服STL网格化文件存在容易丢失精度等固有缺陷,提出基于STL的精确自适应分层系列算法,从提高分层截面的轮廓曲线精度出发,同时考虑到后续数控插补的适应性,采用曲率连续的适应性强的Clothoid曲线拟合算法,重构曲线轮廓并得到拟合加工点;同时在自适应分层中采用垂直轮廓参考曲线上点的切线角决定切片的厚度,有效提高了切片精度和效率,最后采用熔融沉积成形系统进行快速成形验证。结果表明,该方法有效减小了原有的STL格式文件的固有误差,提高了快速成形制件的加工表面质量和效率。 相似文献
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一种检验STL文件正确性的新方法 总被引:3,自引:1,他引:2
在快速成型技术中,从CAD系统中生成的STL模型常会包含多种错误,在切片之前必须对相应的STL文件进行正确性检验。针对上述问题,提出了一种检验STL文件正确性的新方法,该方法操作方便,界面友好。 相似文献
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快速成形的成形精度和速度往往是一对矛盾体 ,自适应分层方法是解决这一矛盾很好的方法之一。本文通过分析和比较切片轮廓信息 ,提出了一种简单而实用的适用于STL及PIC文件格式的自适应分层方法 ,并介绍了该自适应分层的算法。该方法在保证制件成形精度的前提下能极大地提高制件的成形速度 相似文献
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Direct Slicing from PowerSHAPE Models for Rapid Prototyping 总被引:4,自引:2,他引:2
X. Chen C. Wang X. Ye Y. Xiao S. Huang 《The International Journal of Advanced Manufacturing Technology》2001,17(7):543-547
Rapid prototyping processes produce parts layer by layer directly from CAD models. An efficient method is required to slice
the geometric model of a part into layers. Several slicing methods are introduced in this paper: slicing from STL files; tolerate-errors
slicing; adaptive slicing; direct slicing; adaptive and direct slicing. PowerSHAPE is a powerful package for building models,
and it provided macro language and picture files for its secondary development work. To meet rapid proto-typing slicing demands,
the author proposes a direct slicing approach based on PowerSHAPE models. In this method, lines, arcs and Bezier curves are
used to describe the section contours. This approach can be used in stereolithography, selective laser sintering, fused deposition
modelling, and other rapid prototyping processes, e.g. laminated object manufacturing. It may be the future solution to existing
slicing problems. 相似文献
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S. H. Sun H. W. Chiang M. I. Lee 《The International Journal of Advanced Manufacturing Technology》2007,34(7-8):702-701
Slicing a 3D graphic model into layers of 2D contour plots is an essential step for all rapid prototyping (RP) machines. Various
methods are available, such as stereo lithography (STL) file slicing, direct slicing and adaptive direct slicing. Amongst
these, adaptive direct slicing is the most advanced for its capability of adapting the slicing thickness according to the
curvature of any contour. In this study, an adaptive direct slicing method complete with the algorithm for calculating the
thickness of each layer is proposed. As an illustration of the method, the algorithm was programmed within the commercial
CAD software package, PowerSHAPE. The method was shown to be fast and accurate in comparison with STL file slicing and direct
slicing, which both used a constant layer thickness.
An erratum to this article can be found at 相似文献
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Direct slicing and G-code contour for rapid prototyping machine of UV resin spray using PowerSOLUTION macro commands 总被引:2,自引:1,他引:2
C. C. Chang 《The International Journal of Advanced Manufacturing Technology》2004,23(5-6):358-365
Rapid prototyping processes produce parts layer by layer directly from 3D CAD models. An important technique is required to slice the geometric model of a part into layers and to generate a motion code of the cross-sectional contour. Several slicing methods are available, such as slicing from sterolithgraphy (STL) files, tolerate-error slicing, adaptive slicing, direct slicing, and, adaptive and direct slicing. This paper proposes direct slicing from 3D CAD models and generating a G-code contour of each layer using PowerSOLUTION software (Delcam International, Birmingham, UK). PowerSOLUTION includes two main modules: PowerSHAPE is used to build 3D CAD models and PowerMILL is used to produce G-Code tool paths. It provides macro language, picture files and cutting paths for secondary development work.The authors used macro commands to write an interface generating direct slicing from 3D CAD models and G-code contours for all layers. Most well-known controllers in the market accept the G-Code. Therefore, it is easier to apply this scheme in a CNC-machining center to produce rapid prototyping such as laminated object manufacturing (LOM) for complex geometries. The interface was successfully applied the interface to the UV resin spray rapid prototyping (UVRS-RP) machine that was developed to produce RP. 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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作为快速成型技术中必不可少的环节,根据对零件制造精度和装配要求及效率的侧重不同,多年来多种分层算法已被国内外学者开发出来。在同等加工条件下,根据加工精度要求和层厚变化的不同,将分层算法大致分为等层厚分层算法和适应性分层算法两类。从常用的立体光刻(STL)模型、原始计算机辅助设计(CAD)模型和点云数据3种数据模型入手,简述了两类分层算法的研究和发展;介绍了采用斜边的分层算法、基于区域划分的混合算法、曲面分层算法等先进分层算法;讨论了分层算法中待解决的问题:直接分层算法的文件格式标准和轮廓的精确拟合等问题。最后,总结得出了分层算法未来的研究方向和趋势。 相似文献
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Mohammad T. Hayasi Bahram Asiabanpour 《The International Journal of Advanced Manufacturing Technology》2009,45(1-2):170-180
This paper explains a new machine path generating system that its output is compatible with different rapid prototyping processes. The basis of this system is direct slicing from design-by-feature solid model. Slicing a computer-aided design (CAD) model through intersecting the model with the XY-plane at each Z increment is a well-known method of path generation. Slicing a CAD model is currently conducted through stereolithography (STL) file slicing, direct slicing, and additive direct slicing. A direct slicing approach inside a design-by-feature solid modeler is proposed. Autodesk Inventor solid modeler, as a design-by-feature solid modeler, is used for 3D solid modeling. The proposed system is implemented by Visual Basic codes inside Inventor. In this approach, first protrusion and subtractive features that form a model are extracted. Then, the intersection of each feature and the XY-plane is identified. Then, the internal and external loops are found. Depending on the specific rapid prototyping (RP) process requirements, internal or external hatch are also computed, respectively. Finally, a continuous path in required format is generated. The system reported in this paper has been successfully tested on several complex 3D models created in Inventor. The system offers customized output for different RP processes that need external or internal hatch pattern. The proposed approach for generating RP machine path through feature recognition inside design-by-feature solid modeler overcomes with the problems that are caused by imperfect STL files. Also, this system is capable of generating code compatible with major rapid prototyping processes. 相似文献
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一种基于STEP的CAD模型直接分层方法 总被引:1,自引:0,他引:1
提出了一种基于产品模型数据交换标准的3维计算机辅助设计实体模型直接分层方法,零件的原始计算机辅助设计模型以产品模型数据交换标准中性文件的格式输入分层系统,系统提取其几何拓扑信息并重建计算机内部几何模型。用户选择零件的制作方向并指定分层厚度后,系统自动对计算机辅助设计模型进行直接分层,分层结果可直接送到各种快速成型系统加工。基于产品模型数据交换标准的计算机辅助设计模型直接分层不依赖任何特定的计算机辅助设计系统,通用性、灵活性好,而且产品模型数据交换标准文件的数据量大大小于STL文件,有利于网络化设计与制造环境下的数据传输与交换。 相似文献
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