共查询到20条相似文献,搜索用时 78 毫秒
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本文提出一种基于逆向工程技术的复杂曲面产品快速制造技术,主要通过3D激光扫瞄测量设备获取曲面数据,根据曲面特征对测量数据进行除噪、压缩、规则化处理,利用曲面型值点直接作成NC刀路。该方法有效避免了繁杂的曲面重构过程,提高了复杂曲面产品制造的效率。 相似文献
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三维散乱数据曲面重构技术综述 总被引:3,自引:0,他引:3
三维散乱数据曲面重构技术是复杂曲面测量几何造型系统的关键技术。它有整体拟合和局部拟合两种方法。局部拟合因其具有与通用CAD系统相同的数学模型,所以它是复杂曲面到量几何造型系统的常用方法。目前,国内外专家学者在这方面做了大量的理论研究和实际探索,并取得丰硕成果。这种将测量系统与造型系统结合起来的曲面重构技术在工程实际中具有广阔的应用前景。 相似文献
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自由曲线曲面测量中的测点布置与准确度 总被引:2,自引:0,他引:2
分析比较了自由曲线曲面测量中三种测点布置方法的B样条拟合准确度,得出在测点数相同的情况下按等弦此近似关系和高布置测点拟合准确度最高。在此基础上分析了曲线的拟合误差与弦高的近似关系和得出的结论,以便根据此近似关系和给定拟合误差按等弦高进行测量。该方法也适用于自由曲面的测量与曲面重构。 相似文献
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为了获得某型挖掘机斗齿点云逆向造型的实体化模型和CAD工程图样,研究了斗齿点云快速实体化的方法.采用基于“曲面重构-实体化-工程图”的逆向设计途径,提出把对精度要求高的内腔和销孔部位及对精度要求一般的斗齿外形分别用Imageware及Geomagic Studio软件完成曲面重构和基于Pro/E软件完成曲面合并和实体化的逆向策略,介绍了斗齿点云的数据分割、曲面重构与合并、实体化以及其工程图获取过程中的主要过程和方法.研究结果表明:对于型面数量多而复杂的斗齿,曲面逆向工具的选取及点云的数据分割方法是否得当是决定曲面和实体模型重建效率和成败的关键,通过恰当选择逆向策略和工具,合理简化点云的分割、曲面重构与合并以及实体模型的建立等,可显著提高逆向设计效率. 相似文献
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Haoran Chen Hao Zhu Zhichao Huang Wenhui Rong Kai Wu 《Advanced materials (Deerfield Beach, Fla.)》2019,31(50)
A heterogeneous catalytic process involves many surface elementary steps that affect the overall catalytic performance in one way or another. In general, a high‐performance heterogeneous catalyst should meet the main criteria: excellent catalytic activity and high selectivity toward target products. Using surface science techniques, the two‐sidedness of the surface reaction mediations can be explored, from the perspectives of the surface and the molecule manipulations. The surface manipulation refers to a reaction that is mediated by composition and structure of the substrate as well as surface species, while the molecular manipulation relates to a reaction that is mediated by the reacting molecule via the precursor selection, environmental control, or external excitation. The best catalytic system should consist of the most efficient catalyst and the best suitable reacting molecule, in addition to its economic benefit and environmental amity. Recent research progress in surface reaction mediation is outlined, and its two‐sidedness is governed by the Arrhenius equation. This should shed new light on the connection between basic theory and surface reaction mediation strategies. To conclude, challenges and possible opportunities are elaborated for efficient surface reaction mediations. 相似文献
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Heterogenous reactions under transport control can be modelled in terms of a film of reaction products covering the reaction surface. Such a surface defines a unique direction in space which may be used to classify transport processes as transverse or longitudinal. Since crossed-gradient transport occurs, a Péclet number Pe is introduced, representing the ratio of the velocities characterizing transverse and longitudinal transport, with transverse transport being by film diffusion of some reacting species and longitudinal transport corresponding to film flow as with wetting processes. If the influence of viscosity is taken into account in terms of a Schmidt number Sc, the long-wave approximation for the evolution of thin films on reaction surfaces is shown to be equivalent to a distinguished limit Pe 0, Sc , while keeping 1/
. The long-wave approximation is derived by an application of the method of strained variables which leads to a film equation for the spatio-temporal evolution of the film thickness h which represents the crucial element for a complete solution of the thermo-hydrodynamics of the layer. Since film generation due to chemical reaction and film removal due to evaporation may compensate for certain thicknesses h, surface phases are found to occur which correspond to stationary layers of uniform thickness. The evolution of the surface layer is shown to be a generalized reaction-diffusion process, with surface waves representing dynamical transitions between surface phases. 相似文献
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基于球面三角网格逼近的等距曲面逼近算法 总被引:2,自引:0,他引:2
给出了一种基于球面三角网格逼近的等距曲面逼近新算法。利用三角网格逼近基球面,然后计算此三角网格按中心沿在曲面扫凉而成空间区域的边界作为等距曲面的逼近。该算法计算简单,方便地解决了整体误差问题,而且所得到的逼近曲面是与原曲面同次数的NURBS曲面。 相似文献
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平衡法测定的是静止表面的表面张力,但若两相界不断更新,则溶质面表面的扩散和吸附未必能达到平衡本文介绍的动态表面张力的测定试验,就是基於测定到达平衡表面张力的时间。 相似文献