齿轮液压泵的结构合理性探讨

在简介了传统的双齿轮泵流量波动大、结构受力对称性差、易产生泄露和磨损等不足基础上,指出研发齿轮泵新型泵体结构的必要性。简要分析了平衡式多齿轮泵、多联齿轮泵、平衡式复合泵的基本原理和结构特征,分析了各自的排量、流量、传动件受力情况等动态特性,提出了改善齿轮泵受力状况、减少磨损、降低泄露、减少流量波动的途径。指出高压化、低流量脉动、低噪声、大排量、变排量、集成化是齿轮泵的发展方向。     

谐波式齿轮泵的流量脉动分析

运用轮齿啮合理论几何运动规律对谐波式齿轮泵的流量特性进行研究,推导出了瞬时流量的计算公式,并与内啮合齿轮泵的流量脉动进行对比。     

活齿泵的试验研究

活齿泵融合了活齿传动理论和内啮合齿轮泵原理，并具有活齿传动结构紧凑、多齿啮合、传动平稳的特点，能够满足液压泵的各种要求。并通过试验验证了活齿泵流量均匀性好的优点。     

一种内啮合行星式自动送料机构

介绍了典型冲压自动化生产的组合模式。提出一种内啮合行星式自动送料机构,并对这种机构的工作原理、运动特性进行了分析与讨论。研究结果表明,内啮合行星式送料机构具有结构紧凑、送料行程大、加速度特性好、运行平衡可靠等优点,可用于多工位自动化冲压件的2d、3d自动送料。     

内啮合齿轮泵内部泄漏流量的建模与实验

根据流体间隙流动特性,分析了内啮合齿轮泵内部结构及其泄漏通道,建立了内部泄漏流量的数学模型;结合NB型内啮合齿轮泵完成了内部泄漏流量的仿真分析并进行了实验验证,为研究内啮合齿轮泵的内部泄漏、容积效率和动态特性提供了理论依据。     

内外啮合齿轮泵与马达传动的特性分析

为了实现齿轮泵输出流量的定级变化、齿轮马达输出转矩和转速的定级变化,设计了内外啮合型齿轮泵和马达,将内外啮合齿轮泵和马达组成传动系统。以内3外2型为例,对内外啮合型齿轮泵和马达的原理进行了分析:泵具有5个独立的油液输出口,通过不同组合可以组成11中不同的供油方式;马达有5个进油口,在普通连接下可以输出11种转矩与转速,在差动连接下可以输出6种转矩与转速。分析结果表明:在内外啮合齿轮泵和马达的传动系统中,通过改变泵的供油组合方式、马达的连接方式,可以定级的改变马达转矩与转速,拓宽了齿轮泵和马达的适应领域。     

多齿轮变量齿轮泵瞬时流量特性仿真分析

针对齿轮泵存在振动与噪声的问题,提出了一种新型结构多齿轮变量齿轮泵。依据流量特性理论分析,采用MATLAB软件编写程序对瞬时流量特性进行仿真分析。结果表明：与普通外啮合齿轮泵相比,该变量泵不仅可以改变排量,使瞬时流量显著增加、流量脉动大幅降低,而且实现了对泵体振动与噪声的有效控制,具有良好的流量特性品质。     

考虑行星轮不平衡影响下的啮合边带特征研究北大核心

啮合边带特征是齿轮箱故障诊断关注的指标,针对行星轮不平衡引起的啮合边带的调制特征未知问题,通过分析振动的传递路径,建立考虑行星轮不平衡质量与时变啮合刚度和太阳轮浮动多因素耦合的行星轮系振动模型。基于该振动模型分析同相位和顺序相位结构特点的行星传动在行星轮不平衡影响下的啮合边带特征;通过与健康状态下系统啮合边带特征的对比,揭示行星轮不平衡引起的啮合边带调制机理;同时分析在不同运行转速和负载工况下行星轮不平衡对啮合边带调制的影响规律,结果表明啮合边带易受转速和负载影响。     

一种新型内啮合齿轮泵的设计计算与制造

1.问题的提出在液压传动和润滑供油中,渐开线外啮合齿轮泵由于“空穴”现象转速不能太高,所以泵的每分钟流量受到限制。另外,外啮合齿轮泵由于受到“外啮合”的影响,所以体积也不会太小。内啮合齿轮泵与外啮合齿轮泵相比,其体积小,并且可通过增大配油窗口以避免“空穴”现象来提高泵的转速,流量可以增大,这在工业实践中是很有意义的。当外转子齿廓曲线左右侧各为一段圆弧,内转子齿廓曲线为短幅外摆线的等距线时,可以圆满地实现上述啮合传动,提高泵的液压特性。油泵的装配简图及内外转子齿形如图1所     

基于MATLAB的六极并联齿轮泵优化设计及分析

针对普通外啮合齿轮泵流量脉动品质差、质量大、成本高等问题,设计一种六极并联齿轮泵。分析六极并联齿轮泵的结构及其工作原理;对六极并联齿轮泵的瞬态流量特性进行分析,推导其单周期内的流量曲线函数;建立基于流量脉动系数、流量脉动频率和泵体体积的数学模型,选取设计变量,确定约束条件,并利用MATLAB优化工具箱中fmincon函数对目标函数进行参数优化。最后对相同理论流量和额定进出口压差下的六极并联齿轮泵及普通外啮合齿轮泵进行瞬态流量仿真和齿轮泵特性计算,并将结果进行对比分析。仿真结果表明：在结构设计合理的情况下,六极并联齿轮泵在减小流量脉动,降低振动、噪声、质量和制造成本,提高工作性能和使用寿命方面具有重要作用。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.