挖掘机行走液压系统换向阀改造方案探讨

介绍我国挖掘机液压系统的基本情况;针对其行走液压系统换向阀大都依赖进口且价格昂贵的问题,提出一种换向阀的电控化改造方案和两种应用方案。改造后的换向阀可替代高压、大流量进口换向阀,提高国内主机厂的利润。     

长江液压件有限责任公司DC25型、2005型起重机多路阀实现升级换代

2005型、DC25型起重机多路换向阀升级换代是适应起重机行业迅速发展，而设计的具有负载反馈和先导液压比例控制的多路换向阀。设计中主要是将先进的负载反馈技术与先导液压比例控制功能溶入2005型和DC25型多路阀中，并注重提高多路阀的各项技术性能，及产品制造过程中的工艺性能，从而保证产品的各项技术指标和性能达到最佳状态。     

基于AMESim的挖掘机负荷传感多路阀建模和仿真

以一种典型的挖掘机多路阀为例,利用AMESim软件的HCD液压元件库构建多路阀的模型以及挖掘机液压系统的仿真模型,验证多路阀的动态特性,为多路阀设计中的参数选择提供参考。     

电液提升器多路换向阀流道压力损失仿真分析

大功率拖拉机电液提升器多路换向阀内部流道的几何结构会直接影响流道压力损失大小,较大的压力损失会严重影响整个多路换向阀的液压输出功率,从而制约着拖拉机电液提升器整体的动态性能。为提高加工效率、降低局部压力损失,采用机械加工和铸造相结合的方法设计了一种新的多路换向阀内部流道。在对多路换向阀流道压力损失进行理论分析的基础上,运用ANSYS有限元流场分析模块,对油液在多路换向阀不同流道内的流动状态和压力损失进行了三维数值模拟与分析。仿真结果表明:该多路换向阀的流道压力损失满足设计要求,能够用于大功率拖拉机电液提升器。     

液压挖掘机动臂无动力下放系统的研究

针对目前液压挖掘机动臂有动力下放系统所使用的节流阀节流面积固定、回油管路长、阀口发热大、能耗高及易爆管等问题，采用增加防爆管阀、电磁阀、压力开关、控制器及改变多路阀中位机能等措施，研制了一种发热小、能耗低、启动平稳、结构简单、成本低、无故障使用寿命长的液压挖掘机动臂无动力下放系统。试验结果表明：采用动臂无动力下放系统实现了节能减排，比有动力下放系统发热减少近50%，为散热系统减轻了负荷。     

多路阀家族又添新成员电磁遥控多路阀在长江液压件厂通过鉴定

多路换向阀家族,又增添新的成员。一种国内首创的新型节能液压元件—DD22型电磁遥控多路换向阀,在长江液压件厂研制成功,经主机工况考核,性能可靠、质量稳定。并于1992年12月15日通过了由省、市有关单位组织的技术鉴定。     

液压挖掘机执行机构的速度调定系统设计

针对目前液压挖掘机执行机构的速度调定需要通过繁琐地更换多路阀阀芯来实现的问题,基于液压挖掘机的电液比例技术,设计一套液压挖掘机执行机构的速度调定系统,阐述了系统的组成、工作原理以及速度调定功能的程序实现方法。该系统可以让驾驶员根据各种要求通过电控手柄调定液压挖掘机执行机构的速度,尤其是两个执行机构复合运动的速度,无须更换多路阀阀芯,且速度调定后会被PLC记录并以此替换挖掘机控制器中的速度数据,保证挖掘机执行机构按照调定后的速度工作。     

双阀芯挖掘机铲斗联液压系统特性分析

介绍了双阀芯多路阀和单阀芯多路阀的不同点,对双阀芯多路阀进行了原理分析和数学建模,通过AMESim和ADAMS软件对双阀芯多路阀挖掘机和单阀芯多路阀挖掘机的铲斗联液压系统进行了联合仿真分析,并分别对两台挖掘机做了实验测试,仿真和实验结果表明,双阀芯多路阀挖掘机整体性能更优。     

起重机液压多路换向阀试验台的研制

针对目前液压多路换向阀试验存在的问题,设计了同时可对两台多路换向阀进行试验的液压系统,开发了基于工业控制计算机的试验测试系统,采用多线程技术对试验数据进行实时采集,实现了行业标准要求的各项出厂性能试验。工业性试验结果表明:试验台性能稳定、工作可靠。     

工程机械液压多路阀试验台设计开发

工程机械多路阀试验台用于挖掘机、装载机、叉车等液压多路阀性能检测试验。设计并制造了多路阀性能测试试验台,主要设计了液压系统、电控系统与数据采集系统。试验台测试项目与技术参数都达到了国内同类产品先进水平。     

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.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.