共查询到19条相似文献,搜索用时 219 毫秒
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基于点云的汽车车身外覆盖件曲面逆向设计一直是困扰车身开发人员的技术难题,解决这一问题对于缩短车身开发时间有重要的意义.概述汽车A级曲面的理论和方法,探讨制定了逆向设计流程.以某车型汽车发动机罩外板A级曲面的设计为例,阐述设计方案、轮廓线提取和曲面生成等关键技术,解决了设计中出现的问题. 相似文献
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陈玉文 《现代制造技术与装备》2009,(6):10-11
Imageware是一门专业的逆向设计软件,该软件逆向设计功能强大、用途专一.汽车零件点云数据经点云处理、构造8个面(拟合平面A、拟合平面B、圆角曲面C、自由曲面D、自由曲面E、圆角曲面F、圆角曲面G、圆角曲面H)及修剪面的边界三步,便可完成该产品的外形逆向设计.利用Imageware可大大提高产品逆向设计的效率. 相似文献
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Imageware是一门专业的逆向设计软件,该软件逆向设计功能强大、用途专一.汽车零件点云数据经点云处理、构造8个面(拟合平面A、拟合平面B、圆角曲面C、自由曲面D、自由曲面E、圆角曲面F、圆角曲面G、圆角曲面H)及修剪面的边界三步,便可完成该产品的外形逆向设计.利用Imegeware可大大提高产品逆向设计的效率. 相似文献
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基于三坐标测量机自适应测量的自由曲面逆向 总被引:3,自引:0,他引:3
自由曲面的精确测量和重构是决定具有自由曲面特征的零部件复现精度的重要因素,传统逆向中测量与重构是相互独立又不能有效评估的。为提高自由曲面测量速度和重构精度,基于三坐标测量机(Coordinate measuring machine,CMM),提出自适应测量的曲面重构方法。测量过程中,通过不断拟合样件上已测点,预算待测点及其测量矢量,指导CMM自动采集曲面上数据。由点云拟合自由曲面模型后,检验拟合模型上点与样件上相应点的误差;若误差偏大,则在测量点云中加入检测点后重新拟合曲面,进一步检测重拟合实体模型直至满足精度要求,得到精准数据点和精致的自由曲面模型。辅以计算机图形可视化实例验证本法,测量精度及其重构精度可达μm级,具有自由曲面特征的零部件整个逆向周期呈数量级下降,算法鲁棒性强。 相似文献
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论述了从三坐标测量机得到的数据重建模具CAD模型的工作过程,包括点云的预处理如点云对齐、误差点剔除;曲面重构:包括点云的网格化、孔洞填充、边界处理、曲面拟合及曲面评估.利用Geomagic软件完成了对某梁的逆向设计,证明了反求工程理论的可行性. 相似文献
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为提高自由曲面测量速度和重构精度,基于三坐标测量机CMM,提出自适应测量的曲面重构方法。测量过程中,通过不断拟合样件上已测点,预算待测点及其测量矢量,指导CMM自动采集曲面上数据。由点云拟合自由曲面模型后,检验拟合模型上点与样件上相应点的误差;若误差偏大,则在测量点云中加入检测点后重新拟合曲面,进一步检测重拟合实体模型直至满足精度要求,得到精准数据点和精致的自由曲面模型。辅以计算机图形可视化实例验证本法,测量精度及其重构精度可达μ级,具有自由曲面特征的零部件整个逆向周期呈数量级下降,算法鲁棒性强。 相似文献
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指出非均匀有理B样条方法的一系列优良性质及其对车身曲面设计具有的良好适应性,建议应在车身曲面造型中尽快推广应用。文中还从NURBS方法的原始定义出发推导了具有实用意义的算法,并建立了用于车身曲面几何造型的系统。最后给出了设计实例。 相似文献
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轿车参数化分析模型的构造及应用研究 总被引:4,自引:0,他引:4
给出了基于三箱式轿车结构共性的参数化分析模型,并根据车身概念设计的流程和特点构建了概念设计阶段的车身开发平台,实现了轿车参数化分析模型和车身开发平台的信息集成,使设计人员可以在统一的操作环境下基本实现对汽车车身概念设计过程的控制。系统实现了车身早期开发CAD与CAE的集成,提高了结构方案选择的效率和结构设计的可靠性。 相似文献
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产品反求CAD建模工程化技术研究 总被引:2,自引:0,他引:2
研究了模型边界处理方法及复杂曲面局部特征设计方法,总结了CAD模型边界的三种获取方法,提出了基于零件视图投影原理,从2D图纸合成3D边界的技术方案,提出了一种以特征点为导向、基于多视图连续变换原理的3D边界和初始曲面模型匹配方法;提出了边界特征和内部特征曲面设计方法,给出了复杂形状产品反求CAD建模应用实例。 相似文献
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在中等尺寸齿轮测量中,通常以轴线作为测量的基准,但对特大型齿轮来说,要精确获取其轴线存在较大困难。为了特大型齿轮特征线测量问题,本文提出并采用了三维测量与评定的方法。首先利用激光跟踪仪进行被测齿轮的粗定位,获取被测齿轮与三维平台的相对位置关系;然后利用所设计的三维平台在被测齿面获取大量的数据点,对这些数据点进行NURBS曲面拟合,建立真实齿面的三维参数化模型;最后将所建立的参数化模型与理论模型相比较得到齿廓等偏差。实验结果表明,该方法在解决特大型齿轮特征线测量方面具有较好的可行性。 相似文献
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A Reverse Engineering Approach to Generating Interference-Free Tool Paths in Three-Axis Machining from Scanned Data of Physical Models 总被引:3,自引:4,他引:3
C.-M. Chuang C.-Y. Chen H.-T. Yau 《The International Journal of Advanced Manufacturing Technology》2002,19(1):23-31
An NC tool path is usually generated by sweeping parametric surfaces of a CAD model. In modern design, freeform or sculptured
surfaces are increasingly popular for representing complex geometry for aesthetic or functional purposes. Traditionally, a
prototype is realised by machining the workpiece using the NC codes generated from a CAD model. The machined part can then
be compared with the CAD model by measurement using a coordinate measuring machine. In this paper, a reverse engineering approach
to generating interference-free tool paths in three-axis machining from the scanned data from physical models is presented.
There are two steps in this procedure. First, a physical model is scanned by a 3D digitiser, and multiple data sets of the
complex model are obtained. A surface registration algorithm is proposed to align and integrate those data to construct a
complete 3D data set. A shortest-distance method is used to determine the connecting sequence of the neighbouring points between
two adjacent scan lines, such that the scanned data are converted into triangular polygons. Tool paths are then generated
from the tessellated surfaces. Using the Z-map method, interference-free cutter-location data are calculated, relative to
the vertex, edges, and planes of the triangles. The algorithms for tool-path generation are usually different for cutters
of different geometries. Some algorithms found in the literature require complex numerical calculations and are time consuming.
In this paper, an efficient algorithm is developed to calculate interference-free cutter-location data by easy geometric reasoning
without complex computation. This robust method is suitable for generally used cutters such as ball, flat, and filleted end
mills, and the time taken to obtain full tool paths of compound surfaces is short. Some real applications are presented to
validate the proposed approach. 相似文献
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基于三角曲面的逆向工程CAD建模方法 总被引:15,自引:1,他引:15
根据目前逆向工程CAD建模中存在的问题,提出一种基于三角Bezier曲面模型初始表达的跨平台产品逆向工程CAD建模策略,既能利用三角Bezier曲面的优势,又能有效地与通用CAD软件集成。对涉及产品逆向建模方案、数字化测量规划、实际建模过程和再创新设计等具体内容进行了详细阐述,并结合具体实例说明了该方法的可行性和有效性。 相似文献
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Accurate evaluation of free-form surface profile error based on quasi particle swarm optimization algorithm and surface subdivision 总被引:2,自引:2,他引:0
Although significant progress has been made in precision machining of free-form surfaces recently, inspection of such surfaces remains a difficult problem. In order to solve the problem that no specific standards for the verification of free-form surface profile are available, the profile parameters of free-form surface are proposed by referring to ISO standards regarding form tolerances and considering its complexity and non-rotational symmetry. Non-uniform rational basis spline(NURBS) for describing free-form surface is formulated. Crucial issues in surface inspection and profile error verification are localization between the design coordinate system(DCS) and measurement coordinate system(MCS) for searching the closest points on the design model corresponding to measured points. A quasi particle swarm optimization(QPSO) is proposed to search the transformation parameters to implement localization between DCS and MCS. Surface subdivide method which does the searching in a recursively reduced range of the parameters u and v of the NURBS design model is developed to find the closest points. In order to verify the effectiveness of the proposed methods, the design model is generated by NURBS and the measurement data of simulation example are generated by transforming the design model to arbitrary position and orientation, and the parts are machined based on the design model and are measured on CMM. The profile errors of simulation example and actual parts are calculated by the proposed method. The results verify that the evaluation precision of freeform surface profile error by the proposed method is higher 10%-22% than that by CMM software. The proposed method deals with the hard problem that it has a lower precision in profile error evaluation of free-form surface. 相似文献
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