基于正交试验设计的比例方向阀响应时间优化

以一种大流量比例方向阀为研究对象,利用AMESim软件搭建仿真模型,通过正交试验对其关键结构参数进行改进,获得最优化响应特性。将回液阀芯响应时间、进液阀芯开启和关闭响应时间作为评价指标,研究环形阻尼孔、回液阀芯外径、控制腔直径和锥阀口直径4个因素对比例方向阀的影响规律。结果表明：回液阀芯外径对回液阀芯响应时间影响显著,控制腔直径对进液阀芯开启响应时间和关闭时间影响显著;最优结构参数为环形阻尼孔径2.0 mm、回液阀芯外径30 mm、主阀控制腔直径25 mm、锥阀口直径31 mm;与优化前相比,优化后比例方向阀的回液阀芯响应时间减小22.72%,开启和关闭响应时间分别减小34.29%和66.44%,满足优化要求。     

先导式水压溢流阀静动态特性的仿真研究

结合水介质的特性及典型先导式油压溢流阀的结构,分析了先导式水压溢流阀存在的关键技术难题,在此基础上设计了一种新型的先导式水压溢流阀.针对关键技术难题,在结构上主要采取了如下措施:在溢流阀入口设置固定阻尼孔和二级节流主阀口以减小气蚀;在材料上阀芯采用奥氏体不锈钢,阀套采用铝青铜QA19-4增加阀的抗气蚀和抗腐蚀能力;阀芯结构采用异性结构保护重要过流阀口;阀芯上加组合密封件以减少泄漏和拉丝侵蚀.对改进后的溢流阀的静态特性进行了分析,并采用AMESim对溢流阀进行了建模,分析了不同参数对阀动态特性的影响.通过静动态分析,增强了溢流阀性能的可靠性.     

复合阻尼对锥阀压力特性的影响

针对独立阻尼调压锥阀工况适应能力差等问题,提出一种复合阻尼调压锥阀,利用AMESim平台搭建系统仿真模型,与普通锥阀进行对比分析,并分析了复合阻尼调压锥阀减振调压的影响。结果表明:在一定结构参数条件下,复合阻尼调压锥阀具有更好的静态特性且动态特性得到优化;半锥角、孔径对复合阻尼调压锥阀减振调压能力有重要影响。     

阀座带锥的圆锥阀流场分析

对阀座带锥度的锥阀流场进行了数值模拟,通过分析得到了流场内部的压力场、速度场值等流场特征参数.根据锥阀在不同工况下的流量和阀口压力分布,可求得阀芯受到的轴向力和流量系数.所得结果为求得锥形阀芯溢流阀特性提供了依据.     

超磁致伸缩直动式高频电液伺服阀的建模与动态仿真研究

提出一种基于超磁致伸缩转换器的新型直动式高频电液伺服阀（GMM高频伺服阀）,介绍了GMM高频伺服阀的结构组成和工作原理,在建立其数学模型的基础上,构建了AMESim仿真模型,仿真分析供油压力、阀芯与阀套间的径向间隙、阀芯圆角、等效质量、阻尼系数和液动力等不同参数对伺服阀输出流量和动态特性的影响。仿真结果表明：GMM高频伺服阀在10 MPa供油压力下,输出流量可达6.09 L/min,上升时间仅为0.5 ms,超调量为11.3％,具有良好的静动态特性;径向间隙大于24μm时,对伺服阀的输出流量和动态特性影响较大;减小等效质量、增大阻尼系数、阀芯保持锐边,可以提高伺服阀的动态特性;供油压力和液动力对伺服阀动态特性无显著影响。仿真结果为GMM高频伺服阀的结构设计和结构参数优化提供了理论依据。     

铝合金液压阀岛中溢流阀结构设计和静态特性计算

分析溢流阀在铝合金液压阀岛中的作用及其设计时须考虑的参数;根据铝合金液压阀岛的要求确定溢流阀为直动式,通过对直动式溢流阀工作原理的分析及其各种结构的性能比较,确定阀芯结构为锥形。计算了溢流阀的通径d、阀芯与阀套之间的间隙Δr和锥阀锥角α等主要几何尺寸以及在最高调定压力p1max下阀芯额定开口量x10、液压卡紧力FK和阀的弹簧刚度K1及预压缩量x0,为溢流阀的设计提供参考。     

以高速开关阀为先导阀的锥阀性能研究

通过分析以高速开关阀为先导阀的锥阀控制腔压力动态响应过程,以及高速开关阀控制锥阀的流量特性,得出了如下结论:锥阀控制腔压力响应过程受阀芯阻尼孔直径及控制腔体积的影响,其中阻尼孔直径对控制腔压力响应速度影响不大,但是稳定后的控制腔压力则随阻尼孔直径变大而变大;控制腔体积越大,其压力响应速度则越慢;当高速开关阀的调制率在一合适范围内变化时,高速开关阀作为先导阀能实现对锥阀较大流量的线性比例控制.     

锥阀芯稳态液动力补偿研究

溢流阀主阀芯的稳态液动力使溢流阀存在较大的调压偏差,降低了其静态性能指标。采用在溢流阀主阀芯（锥阀芯）上加突缘结构来补偿稳态液动力。采用CFD工具对主阀口流场进行仿真,研究突缘结构尺寸、位置及阀芯锥角对主阀芯稳态液动力补偿的影响。结果表明：突缘结构能实现阀芯液动力补偿,但随着阀芯开口量的增加,补偿会由欠补偿变为过补偿;当突缘长度为0.5 mm、距离阀座为1 mm时,液动力补偿效果最好。     

基于AMESim卸荷溢流阀阻尼孔优化分析

为了优化卸荷溢流阀的动态性能,建立卸荷溢流阀模型,分析卸荷溢流阀在受到流量冲击时安全阀阀芯位移、安全阀出口流量、安全阀进口压力以及主阀出口流量变化情况,得出合理的阻尼孔直径,并在此基础上仿真分析流量平衡时各阀口的流量曲线。结果表明:阻尼孔直径值为1 mm时,易于卸荷溢流阀的性能平衡;各阀口受到流量冲击时,流量波动0.06 s后均趋于稳定。     

锥阀式数字比例溢流阀特性的试验研究

研究以高速开关阀为先导阀、安全阀为锥阀结构的数字比例溢流阀特性。搭建数字比例溢流阀试验平台,开展了锥阀式数字比例溢流阀的试验研究。试验结果表明:当高速开关阀控制信号的频率为50 Hz时,既能保证一定的有效占空比范围,又能满足系统的频率响应性能;锥阀式数字比例溢流阀的重复特性较好;在占空比正反向连续变化时,锥阀式数字比例溢流阀的系统输出压力在同一占空比时的变化很小,滞环现象不明显,能够满足系统控制的要求;不同流量对占空比范围和最高压力影响不大,但影响系统最低压力;锥阀式数字比例溢流阀调节压力在10%~60%范围内近似线性变化,比滑阀式结构调压性能好。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

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。     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

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.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.