模拟铣削力试验装置若干控制问题的研究

在研发测试数控机床滚动功能部件精度保持性试验台的基础上,设计一套施力机构,通过控制该机构模拟工作台在立式铣削工况下的受力并完成性能参数的动态测试。建立力学模型,利用力与力矩相等原理推导出模拟施加力与铣削力之间函数关系,并对其进行分析,发现在铣刀进给方向发生突变时模拟力也会发生突变,施力机构无法实现该模拟力的突变,经验证在进给方向发生突变的位置处添加圆角可消除突变;利用VB完成对各模拟力及力矩随时间变化显示界面的程序设计,使用户能够直观地了解变化规律。操作者通过建立的系统界面实现对试验台各功能控制。     

微机在汽车离合器综合性能试验台中的应用

通过采用先进的计算机技术来模型实际路面条件，真实地反映离合器在实际行驶时的工作状况，且根据不同的参数设置可以利用同一个试验台进行多种车型的模拟，从而检测多种型号离合器的性能参数，该试验台的用微机作为试验台的测控核心，使用方便 灵活，试验过程的测试与控制均自动完成，采用Windows界面，人机界面友好，集图形文字于一体，测试效率和测试精度高。     

铁道车辆转向架性能参数测试台

本文详细介绍了所研制的铁道车辆多功能性能参数试验台的组成原理和功能。试验台可完成车体静强度测试、转向架参数测试，并可对车辆零部件进行静强度和疲劳试验。最后给出了一些参数的测试方法和测试结果。     

航空薄壁件铣削力有限元分析

在分析刀具与工件在装配模型中位置关系的基础上,将平行运动载荷与转动载荷同时施加到刀具模型上,建立了刀具次摆线运动的铣削有限元模型。为了减少模拟的时间,使用过渡网格划分技术对模型进行了优化处理。在考虑工件材料性能参数基础上,利用有限元平台ABAQUS软件,研究了航空铝合金薄壁件铣削过程中铣削力的变化规律。模拟结果基本符合实际,说明有限元模型是正确的,对后续研究工作有一定的参考意义。     

Structure Analysis and Application of Table Guideway of Heavy-duty CNC Gantry Type Boring and Milling Machine

针对重型数控龙门镗铣床工作台承载状况,分析滚滑复合导轨和静压导轨的特性,确定该机床工作台导轨结构方案,并在分析工作台载荷的基础上对液体静压导轨进行设计计算.经测试检验和实际应用:设计的导轨完全满足工作台精度和性能参数要求.     

MECHATROLINK-Ⅲ总线型机床模拟器的设计与实现

目前MECHATROLINK-Ⅲ总线型数控系统各控制功能和运行状态的验证测试多采用伺服模拟器加开关量手动输入输出的方式,这种方式只能得到少数几个状态而且不能反应出机床电气运行特性.针对现有测试技术的缺点文中提出一种总线型机床的模拟测试方法.在分析MECHA-TROLINK-Ⅲ协议和机床模拟器需求的基础上,设计机床模拟器硬件,并进行相关软件的开发,为数控系统提供一个闭环的测试平台.在实际应用中该机床模拟器能够完成伺服系统的模拟和机床电气系统的模拟.     

重型数控龙门镗铣床工作台导轨结构分析与应用实例

针对重型数控龙门镗铣床工作台承载状况,分析滚滑复合导轨和静压导轨的特性,确定该机床工作台导轨结构方案,并在分析工作台载荷的基础上对液体静压导轨进行设计计算。经测试检验和实际应用:设计的导轨完全满足工作台精度和性能参数要求。     

基于Modbus的数控系统监控功能设计与实现

传统数控系统的人机界面采用编程方式实现,不利于修改和扩展功能,并且用户体验较差。通过对现有蓝天数控系统"GJ301"的体系结构和基本功能的分析研究,设计了在局域网内监控数控系统的上位机控制系统。上位机采用嵌入式WINCE操作系统和MCGS嵌入版组态软件,人机界面的设计主要用MCGS提供的绘图工具箱来完成。上位机通过ModbusTCP协议向数控系统发送命令和采集信息。在数控系统任务控制模块的每个任务周期里通过单独的线程维护远程连接,解析执行命令并反馈结果。经过测试,该监控功能运行良好且操控更加简便灵活。     

电动力加载台测控系统建模与设计

设计了一种新型力加载结构,通过滚珠丝杠副实现力矩到力的转化,完成对被测机构的力加载。给出了加载台的结构组成及系统工作原理,并建立了系统的数学模型。采用了PID控制和基于结构不变性原理的复合前馈控制策略对系统进行了设计,仿真结果表明:系统可完全满足测试指标要求。该系统相比传统力加载台,具有转动惯量低、加载电机功率小等优点,并具有一定的工程参考价值。     

一种虚拟轴工作台并联机构的力分析与样机模型

提出一种新型四自由度虚拟轴工作台并联机构的力分析方法.用分析静力学的虚位移原理及雅可比矩阵建立并联机构的静力平衡方程,并计算和仿真验证该方程.用达朗贝尔原理建立机构的动力学模型,在ADAMS软件中作机构的动力学仿真分析.实例证明可得到该并联机构静力平衡和动力平衡的主动副驱动力设计条件.此外,设计并创建了样机的三维CAD模型,该模型可直接用于虚拟轴工作台的样机制造.     

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.