MG 300型采煤机牵引部液压自动调速系统研究

介绍一种MG-300型采煤机牵引部液压自动调速系统的工作原理,其牵引部不仅负担采煤机工作时的移动和非工作时的调动,且牵引速度直接影响采煤机的效率以及采煤质量。结合采煤机实际工作状况,通过对现有液压自动调速系统的分析,采用反馈校正等方式,实现了采煤机满载运行。     

电牵引采煤机摇臂故障诊断系统的研制

根据电牵引采煤机摇臂故障诊断系统要求,对电牵引采煤机摇臂故障诊断系统的硬件进行设计。基于Lab VIEW软件平台,开发了采煤机摇臂信号监测分析软件,完成了电牵引采煤机摇臂故障诊断系统的研制。该系统可实现采煤机摇臂各类传感器信号的实时监测、振动分析、诊断分析等功能,可有效评估当前电牵引采煤机的工作状态,提高电牵引采煤机的运行可靠性。     

采煤机模拟实验装置液压系统设计

分析采煤机模拟实验装置的组成及工作原理,设计该装置的调高与牵引液压系统回路,对液压系统的主要元件包括液压缸、比例方向阀和液压泵进行了计算选型,对类似液压系统的设计及选型有较大的参考价值。     

采煤机强迫润滑机构的开发和应用

急倾斜大俯采工况下,采煤机牵引部二级行星减速机构行星架支撑轴承容易缺油,导致该轴承经常损坏,影响煤矿正常生产。西安煤矿机械有限公司开发了采煤机牵引部强迫润滑机构,该机构能够保证行星架支撑轴承的良好润滑,解决了特殊工况下采煤机牵引部的润滑难题,达到润滑效果良好、工作可靠、设备运转正常的目的。     

大功率薄煤层交流电牵引采煤机的研制

本文介绍了一种适用于薄煤层一次采全高的大功率薄煤层交流电牵引采煤机,对牵引部、摇臂、滚筒、电气系统及智能化设计方面需解决的关键技术及设计中采取策略进行详细的分析。该大功率薄煤层采煤机满足了目前薄煤层煤矿的生产需求,对提升我国煤炭采掘设备装备水平有着重要意义。     

列车轮对测量机液压系统设计与实现

针对列车轮对测量机的测量需求,设计了整个液压系统。对轮对液压系统的控制时序进行分析,对机构中的左/右顶紧、左/右升降、左/右拨叉、摩擦轮进给7处液压缸进行合理的布置,并进一步计算了液压系统的主要参数,合理选择了液压系统的元器件。设计了整个控制回路,并进行了升降机构的同步回路设计。该液压系统已实际运行3.5年。结果表明:该液压系统的压力损失在适宜范围内,在测量过程中液压系统工作正常、可靠。     

专用自动钻床液压传动系统设计

本文以一台专用钻床为例，介绍了液压系统的有关计算、设计步骤、元器件选择；最后重点介绍了该液压系统的电气控制回路的设计方法。     

关于液压系统中“液阻”的探讨

以液压系统的液压压力、流量和功率为参量,借鉴欧姆定律提出“液阻”概念,并以此初步归纳了各种“导流”液压元器件的“液阻”共性.藉此各种液压元器件所共有的“液阻”属性,探讨了面向液压系统的数学运算及分析评估的可行性.     

某型飞机双发失效时液压能源系统性能分析

为研究某型飞机液压能源系统双发失效时能否满足双发失效时液压用户的流量和压力需求,根据系统架构、主要元器件参数及用户需求等输入,建立了该型飞机3号液压能源系统的AMESim仿真模型,并对系统压力和流量性能进行了仿真。仿真结果表明:液压用户的压力分析结果均大于其压力需求,验证了某型飞机液压能源系统的设计。     

基于物理模型的电液调节阀动态设计与研究

介绍了基于AMESim平台的液压系统动态设计原理.在此基础上,设计了电液调节阀的液压驱动系统,建立了电液调节阀的物理仿真模型并进行了动态响应的仿真分析.结果表明,基于物理建模方式建立的仿真模型能比较地好反映液压系统各元器件之间的相互影响关系,通过对系统工况进行动态响应仿真可以使系统的设计缺陷在制造出具体的液压系统前就显现出来并得到及时有效的处理,从而缩短设计周期,降低制造成本.     

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.     

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.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

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.