快速成形技术及其工艺分析

快速成形技术是一种全新的制造技术。本文介绍了快速成形技术的基本原理 ,提出了基于快速成形技术的产品开发模式以及快速成形技术的特点。在此基础上 ,从输入模型、成形方法、成形材料和应用领域四个方面对快速成形工艺进行分析 ,最后进一步讨论了几种典型的快速成形工艺。     

快速成形技术的研究热点及其展望

介绍了快速成形技术的特点和生产过程,指出快速成形技术的研究热点是研究新的成形设备应用软件、扩充现有成形技术的应用领域、探索新的成形工艺和开发新型材料等几个方面,展望了快速成形技术在未来的发展趋势。     

三维打印快速成形技术及其应用

三维打印快速成形技术与其他快速成形技术相比具有众多优点,被认为是快速成形领域最有生命力的新技术之一。本文根据喷射材料的不同,将三维打印快速成形技术分为粘结成形三维打印和直接成形三维打印,分别介绍了它们的工作原理、系统组成和结构特点。结合三维打印快速成形技术独特的成形工艺特性,对其在产品的概念原型与功能原型件制造、生物医学工程、制药工程和微型机电制造等领域的应用前景进行了分析和展望。     

快速成形技术及其发展趋势

本文介绍了快速成形技术的原理及快速成形的全过程,分析了快速成形的主要工艺方法和今后的发展趋势.     

快速成形是支持产品创新的关键使能技术

论述快速成形（ＲＰ）技术对制造业新产品开发的促进作用。在总结应用快速成形技术经验的基础上,提出一个基于快速成形技术的产品创新流程。分析快速成形技术的应用效益,并提出预测方法。实践表明快速成形技术是支持产品创新的一项关键使能技术。     

第三届全国快速成形与快速制造学术会议征文通知

近年来 ,快速成形与快速制造 (RP&RM)技术迅速发展 ,在国内外的推广应用呈现蓬勃的态势。为了进一步加速发展我国的快速成形与快速制造技术 ,更好地为发展生产力服务 ,为我国的西部开发作出更大贡献 ,经中国机械工程学会特种加工分会快速成形技术委员会决定 ,将于 2 0 0 4年 3月 16日至 19日在昆明召开“第三届全国快速成形与快速制造学术会议”。此次学术会议应征优选论文将编辑成《快速成形与快速制造技术》一书 ,由国家正规出版社正式出版。现将有关事项通知如下。征文范围 :快速成形软件与数据处理技术 ;快速成形工艺与设备 ;快速成形…     

快速成形表面精度研究

结合快速成形的工作原理及特点,研究分析了影响快速成形表面精度的主要因素,即有分层处理时,原型堆砌产生的原理性误差、成形加工误差及后处理误差等,提出了通过选择合适的分层厚度,减少机器误差,以及采用良好的后续处理和先进的复合快速成形技术等方法提高快速成形的表面精度。     

金属零件激光直接快速成形技术的研究(上)--国外篇

金属零件激光多层熔覆直接快速成形技术是目前快速成形领域的研究热点,本文系统介绍了国内外激光熔覆直接快速制造成形工艺的最新研究进展。研究表明,金属零件激光熔覆直接快速成形工艺具有常规制造方法无法比拟的优势,有着广阔的发展前景。     

加快我国快速成形技术的应用开发和产业化

简述了我国快速成形技术现状 ,分析了我国快速成形技术产业化过程中存在的主要问题 ,提出了面对入世必须加快推进我国快速成形技术的应用开发与产业化     

低温快速成形与绿色制造

在快速成形技术中,在低温下进行成形制造的新技术、新工艺（即低温快速成形）非常有特色,明显应当属于绿色制造范畴。介绍了两种新的快速成形技术,包括低温冰型快速成形（IRP）和低温沉积生物制造（LDM）,它们均属于微滴喷射方法。都有非常好的应用前景,应当引起重视。     

Electron and light microscopy studies on the domain structures of Zn3B7O13Cl, Zn3B7O13Br and Zn3B7O13I ferroic boracites

The domain structures of Zn₃B₇O₁₃Cl, Zn₃B₇O₁₃Br and Zn₃B₇O₁₃I boracite single crystals were studied by means of polarized light in conjunction with electron microscopy. Single crystals of the three compositions were grown by chemical transport reactions in closed quartz ampoules, at a temperature of 900 °C and were examined by polarizing optical microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For both PLM and SEM, the same as‐grown samples were used without having to resort to metallization of the crystal faces. For TEM the single crystals were crushed and mounted on holey carbon films. Comparative electron microscope images were useful for revealing the domain structure of these ferroelectric/ferroelastic materials previously observed between the crossed polars of an optical microscope. X‐ray diffraction analysis of the pulverized crystals was performed for this triad of halogen boracites containing zinc as a common metal.     

GT/CAD/CAPP/PDM/ERP系统集成研究

研究ETO生产方式下以成组技术为基础的CAD/CAPP/PDM/ERP的集成方法,包括面向CAD/CAPP/PDM/ERP的集成的成组信息编码,基于成组编码的CAD/PDM集成、CAPP/PDM集成和PDM/ERP集成.提出了基于成组技术的CAD/CAPP/PDM/ERP集成框架,研究了贯穿于CAD、CAPP、PDM与ERP系统的统一的成组编码方案和信息编码方案.     

Cylindrical specimens for KIC of rocks

Stress intensity factors for pairs of diametrically opposite radial cracks on the inside of a jacketed pressurized hole in a thick cylinder have been calculated by using finite element technique. Burst tests on thick cylinder rock samples under above conditions have been performed and the K_IC values for Antrim Shale and Limestone determined. The method is very convenient for rocks whose samples are often available in form of cylindrical bars drawn as cores from underground drilling.     

基于太赫兹光谱的人参和西洋参鉴别

为了快速区分人参和西洋参，依据两者所含的人参皂苷在太赫兹波段具有不同指纹光谱，提出了一种基于人参皂苷的太赫兹光谱鉴别人参和西洋参的方法。采用MATLAB软件识别人参和西洋参的太赫兹光谱，同时根据太赫兹光谱特征并通过标准的主成分分析(PCA)区分出人参、西洋参。实验结果表明，基于太赫兹光谱的主成分分析可精确区分出人参、西洋参，并且还可以应用于其他类似物质的区分中。     

Characterization of cast Al86Mn3Be11 alloy

An Al₈₆Mn₃Be₁₁ alloy cast into copper mould was subjected to metallographic investigation. The as-cast microstructure consisted of a quasicrystalline icosahedral phase (i-phase), Be₄AlMn phase and, occasionally, a hexagonal phase. Al-rich solid solution represented the dominant phase. The chemical compositions of phases were determined using AES. The composition of the Be₄AlMn slightly deviated from the stoichiometric composition, whereas the composition of the i-phase was approximately Al₅₂Mn₁₈Be₃₀, containing an appreciable amount of Be. The average composition of the hexagonal phase was Al₆₆Mn₂₁Be₁₃. Deep etching and particle extraction provided a deep insight into the three-dimensional morphology of the i-phase and the hexagonal phase, whereas Be₄AlMn was slightly attacked by the etchant. The i-phase was present predominantly in the form of dendrites and a rodlike eutectic phase. The hexagonal phase was primarily in the form of hexagonal platelets, whereas Be₄AlMn was rather irregular in shape. The morphology of the i-phase can be explained by predominant growth in 3-fold directions and the lowest energy of the 5-fold planes, leading to the faceting and adopting a pentagonal dodecahedron shape. The brightnesses of phases in the backscattered electron images were rationalized by determining their backscattering coefficients. TEM investigation showed considerable phason strain in the i-phase, and the polycrystalline nature of the Be₄AlMn phase.     

Analysis of the Rk surface roughness parameter proposals

European manufacturers have proposed a set of surface roughness parameters based on an examination of the variation in slope of the bearing ratio curve of a surface profile. It is shown, that the proposed procedure provides no useful information, and indeed is misleading, since the bearing ratio curve of even a normally-distributed random surface profile exhibits the expected variation in slope when plotted on rectangular coordinates. On the other hand, the desired information is readily obtained by a similar examination of the cumulative height distribution of a surface profile (the unity complement of the bearing ratio) when it is plotted on normal probability coordinates.     

永磁同步电机积分滑模观测器控制

对永磁同步电机观测器控制进行研究,针对传统滑模观测器存在控制精度低、系统抖振较大的不足,设计了一种永磁同步电机积分滑模观测器控制。积分滑模控制具有控制精度高、系统抖振小的特点。积分滑模观测器可以有效提高电机控制精度,增强控制系统抗干扰能力。采用饱和函数代替符号函数进行滑模控制律设计,降低控制系统固有抖振,使滑模控制动态性能提高。通过仿真验证了积分滑模观测器控制策略的可行性。     

Investigation on the impact behavior of Al2O3-SiC-MgO nanoceramic/metal laminated composite

Lightweight laminated composites containing a ceramic front layer and a metallic backing layer were used in order to protect people, moving equipment, and mobile vehicles from high velocity impact and the increased mobility of mobile vehicles. In this study, by adding10 vol% SiC and 500 ppm MgO nanoscale particles on the microstructure of Al ₂ O ₃ matrix and applying optimum sintering conditions, ceramic performance against high-speed projectile impact was improved. To perform this investigation, a number of target samples with two different types of front layers (alumina and Al ₂ O ₃-SiC-MgO nanocomposite ceramic) were produced. Impact tests were conducted on these samples using 7.62 mm projectiles with a velocity of 820 ± 15 m/s. The amount of bulge and bending of the backing layer caused by impact tests was measured. The results of the impact tests on the samples made of Al ₂ O ₃-SiC-MgO nanocomposite ceramics and alumina were also compared and analyzed. The results indicate that the substitution of Al ₂ O ₃-SiC-MgO ceramic layer — which is proffered in this paper — instead of pure alumina ceramic layer, decreases the areal-density of the samples by at least 30% and improves mechanical properties by about a 60% increase in flexural strength and 100% growth of the energy distribution factor, which impressively increases impact energy absorption.     

Near-field second harmonic imaging of the c/a/c/a polydomain structure of epitaxial PbZrxTi1–xO3 thin films

Near-field optical second harmonic microscopy has been applied to imaging of the c/a/c/a polydomain structure of epitaxial PbZr _x Ti_{1– x} O₃ thin films in the 0 <  x  < 0.4 range. Comparison of the near-field optical images and the results of atomic force microscopy and X-ray diffraction studies show that an optical resolution of the order of 100 nm is achieved. Symmetry properties of the near-field second harmonic signal allow us to obtain good optical contrast between the local second harmonic generation in c- and a-domains. Experimentally measured near-field second harmonic images have been compared with the results of theoretical calculations. Good agreement between theory and experiment is demonstrated.     

Electron microscopy of crack/particle interactions in Al2O3/SiC nanocomposites

Crack/particle interactions in alumina/silicon carbide nanocomposites have been investigated by scanning electron microscopy and transmission electron microscopy, with cracks induced by Vickers microindentation. Intergranular cracks are frequently deflected into grains by SiC particles on grain boundaries inclined to the average direction of crack propagation. This mechanism is proposed to explain the change in the fracture mode from intergranular fracture for monolithic alumina to predominantly transgranular fracture for the nanocomposites. Neither stress-induced microcracking around SiC particles nor significant crack deflection by intragranular particles was found to occur in the nanocomposites. It is argued that an addition of nanoparticles may not be a promising approach for increasing the toughness of alumina.