轨道除雪车液压系统的设计与分析

为解决内蒙赤大白运输段因冬季频繁积雪导致线路中断的实际问题,设计与研究了一种轨道除雪车。以自主研制的轨道除雪车为研究对象,分析了轨道除雪车液压系统相关结构,设计了除雪装置液压系统。根据轨道除雪车的性能指标,对轨道除雪车液压系统主要元件进行了参数设计。在此基础上,运用液压数值分析软件Automation Studio对轨道除雪车除雪装置液压系统进行了数值分析,数值分析曲线直观地显示了集、抛雪液压马达和转向液压马达的流量、转速和压力。对比实测参数值和数值分析结果,两者最大相对误差绝对值小于12%。现场测试表明:轨道除雪车除雪高度大于3 m,除雪宽度大于3.5 m,除雪扬程大于10 m,除雪装置液压系统性能稳定,满足轨道除雪车设计指标。     

摩擦焊机液压系统节能减耗方法

针对当前摩擦焊机液压系统采用定量泵驱动带来的能耗大、油液温升快、焊接参数不稳定等问题,提出了节能型液压系统,即计算机控制下的比例变量泵驱动的施力系统和恒压变量泵驱动的辅助系统.分析了液压系统的节能原理,对两类液压系统的能量参数进行了试验测量.结果表明,节能型液压系统由于采用变量泵供油,流量可根据需要设定或自动调节,减小...     

全液压推土机行驶驱动系统仿真研究

根据全液压推土机行驶驱动系统的工作原理,建立了电液比例控制的行驶驱动系统AMESim仿真模型,并进行了仿真。仿真结果表明:液压马达采用自反馈调节的行驶驱动系统,系统压力处于一个相对稳定的状态,有利于系统的高效率运行;当负载突然增大,液压马达排量相应变化时,系统压力波动较大,但能迅速恢复平稳状态。     

基于AMESim的旋转冲击型锚杆钻机液压驱动控制系统设计与建模仿真分析

设计了旋转冲击型锚杆钻机液压驱动控制系统,分析锚杆钻机工作时,液压冲击系统、推进系统、回转机构(转钎)液压回路及钻机防卡钎回路的工作原理,根据抽象设计变量理论,推导出锚杆钻机性能参数冲击能E、冲击频率f和输出功率N与液压冲击器工作流量Q(或工作压力p)及活塞回程加速行程Sj的关系,采用AMESim软件对其进行建模仿真,根据仿真曲线分析了锚杆钻机在冲击钻进时,系统工作压力和推进力对液压冲击器活塞行程、冲击能、冲击频率和冲击器功率的影响。仿真结果验证了液压驱动控制系统设计的合理性和可行性,为锚杆钻机液压驱动系统设计提供了理论基础。     

基于Automation Studio铲运机液力与静液传动系统对比分析

液力-机械传动系统和液压-机械传动系统是地下铲运机两种重要的传动系统布置方案。针对ACY-10载运为1m~3的小型铲运机传动系统设计,根据铲运机使用要求,设计变量泵、变量马达等元件。采用静液压-机械传动方案,应用Automation Studio搭建整车不同液压系统的分析模型,对铲运机行驶液压系统、转向液压系统、工作液压系统等运行特性进行分析,获得不同工况时系统油路循环,系统所受动载荷特性,系统受动态外载荷作用时工作油缸压力、位置随时间变化曲线。同理根据液力-机械传动系统方案的特点,搭建分析模型,对比分析静液压-机械传动方案和液力-机械传动方案。结果可知:静液压-机械传动方案在最大牵引力、最大铲取力、爬坡能力等方面具有优势,且很好地解决了倾翻油缸系统中出现的波动现象,提高了液压系统的稳定性。可将静液压-机械传动方案作为设计参考。     

565 kW全液压推土机液压行驶驱动系统参数计算

为确定大功率全液压推土机液压行驶驱动系统中重要的液压元件-液压泵和液压马达的类型,针对某565 kW全液压推土机,进行其液压行驶驱动系统的参数计算。提出一种单边回路具有双泵双马达的液压行驶驱动系统结构,并根据其动力传递路线建立系统原理图;基于565 kW全液压推土机的原始设计参数,采用阻力计算法,由牵引平衡求出切线牵引力,进而确定马达的输出扭矩和排量;选取HMV-02系列排量为280 mL/r的液压马达和HPV-02系列排量为165 mL/r的液压泵,作为该565 kW全液压推土机的液压元件。经验证,选取的液压元件可以满足全液压推土机设计要求的有效牵引力;为其他大功率工程机械液压行驶驱动系统的研究提供了参考。     

农用机械液压驱动同步控制仿真分析

“精准农业”对农用机械液压驱动系统提出了更高要求,要求其在行走时具有良好的直线行驶性、高准确性和安全性。为此提出一种缓冲制动回路,在该回路基础上进行同步控制。建立农用机械液压驱动系统原理模型,分析其工作原理,选择控制策略;在AMESim建模,然后在MATLAB/Simulink中建立模糊自适应PID模型,最后进行联合仿真并分析系统同步性和鲁棒性。仿真结果显示：系统启动后0.7 s时达到稳定的目标转速,最大同步误差为121.83 r/min,达到稳定的目标转速前最大超调量为4%,达到稳定的目标转速后同步误差为0.65 r/min;当系统负载波动时,系统也能在0.8 s内达到稳定的目标转速,最大同步误差为30.35 r/min,达到稳定的目标转速后同步误差为0.65 r/min。因此对于该农用机械液压驱动系统,采用主从控制和模糊自适应PID控制,响应速度快,超调量小,鲁棒性好,能够保证农用机械行走时具有良好的直线行驶性、高准确性和安全性。     

基于不二越液压元件的WY-60挖掘机液压系统的改进设计

在分析现行液压系统的基础上,采用体积小、速度快和压力高的不二越液压元件,设计了一种新型液压系统,并成功应用于WY-60挖掘机上。经使用证明:该系统各项性能稳定,且有效缩短了工作转移时间,改善了回转性能,提高了行走速度及驱动压力。同时绘制了行走性能曲线,从该曲线可以看出:挖掘机在行驶过程中,随着负载的增加,双速行走马达会自动切换速度,无需人工操作,从而有效地减少了人工操作量,提高了整机作业效率。     

挖掘机换挡阀阀芯控制特性研究

轮式挖掘机行驶系统朝着高速的方向发展,不同的底盘系统,换挡装置也不相同。以某型液压换挡系统为分析对象,基于AMESim构建了轮式挖掘机底盘驱动及液压系统模型,以HCD库基本模块建立了换挡阀模型,对挖掘机行驶换挡操作进行仿真研究,仿真分析了换挡阀对速度切换的影响,找出换挡阀初始设计的不足,对阀体及阀杆进行了改进设计,并编制了过流面积的计算程序。改进设计后的结果表明:不同挡位间的速度过渡平稳,有助于减小换挡冲击。     

张紧器液压与驱动系统节能分析

铺管船用张紧器属于海上作业设备,要求其在工作过程中尽量减少能耗。对张紧器液压夹紧和电机驱动系统进行节能设计;在液压系统中动力源是液压系统的主要能耗因素,通过分析采用A7V.80.EL型高效、节能、大功率的复合变量泵来匹配液压系统达到节能的目的;在交流伺服电机驱动系统中,根据大功率电机的特点采用变频器对电机进行启停控制,减小启动电流实现节能,同时在电机的运行过程中,通过对功率因数进行模糊控制达到节能目的,并通过试验证明系统节能效果。     

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.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。