并联机床开放式数控系统的研究

综述了作为机床技术、机器人技术相结合的产物——并联机床控制系统的现状和发展前景,介绍了目前并联机床数控系统的几种硬件结构方式,以及数控系统的基本模块,最后提出了并联机床开放式控制系统今后发展方向的一些思路。     

并联机床数控平台建造

针对3－HSS并联机床结构特点，确定了采用“PC＋适配器”建造硬件平台总体结构体系，并对伺服系统、I／O与数控系统的连接及DPRAM的中断设置作了介绍。     

基于DSP的2-HRR并联雕刻机数控硬件系统开发

考虑并联机床运动控制的特点和DSP系统的优点,以ADI公司的ADSP-BF533数字信号处理器为核心,开发了应用于2-HRR并联雕刻机的数控系统.数控硬件系统由"PC ADSP"构成.采用C语言在ADSP-BF533上开发了针对2-HRR并联机构的控制程序.测试结果表明,系统设计合理,能准确地控制并联雕刻机的动作.     

基于DSP和FPGA的运动控制器的设计与实现

针对数控系统的工作特点和要求,通过对TI公司推出的DSP芯片TMS320C6713和ACTEL公司的FPGA芯片A3P400功能和特点的深入分析,给出了一种基于DSP和FPGA的运动控制器的设计与实现.在充分考虑上述芯片特点和资源的基础上,该控制器采用浮点型DSP与FPGA,能够更好地满足数控系统对运动控制单元的实时性和控制精度的苛刻要求.同时介绍了运动控制器的硬件整体结构及主要模块的详细设计,并给出了DSP软件实现的程序结构框架.     

基于运动控制器的激光加工机床数控系统研究

针对现有激光加工机床数控系统的不足,提出了以多轴运动控制器为核心的激光加工机床开放式数控系统设计方案,该方案以运动控制器为CNC控制核心,PC机为支撑单元,对硬件选型和软件设计进行了说明,为激光加工机床数控系统的研究提供了新的思路。     

3-HSS型并联机床数控系统的开放式设计

本文介绍了3-HSS型并联机床数控系统的开放式设计，详细介绍了系统的软、硬件构成。整个数控系统面向最终用户，采用模块化设计，具有良好的可扩展性及可维护性。     

基于LINUX+RTLINUX平台的开放式数控系统的设计

设计了一种基于LINUX+ RTLINUX双内核开发平台的开放式数控系统.该系统采用PCI总线和CUnet现场网络技术,将PC机和专用运动控制芯片MCX314相结合构成多轴伺服电机控制器,并详细介绍了系统的硬件接口设计和LINUX+RTLINUX平台驱动程序以及应用程序的开发方法,并在实际中得到了应用,取得良好的效果.     

虚拟轴机床数控系统手轮功能的开发

由于虚拟轴机床具有非线性映射的运动控制特点，手轮等功能的实现一直是虚拟轴机床数控系统开发中的难点之一，文章介绍了基于“PC＋PMAC”的硬件结构，结合PLC技术、中断技术以及实时多任务调度策略开发虚拟轴机床手轮功能的方法。该方法已成功应用于天津大学自主开发的虚拟轴机床数控系统，取得了良好效果。     

并联运动机床现状与关键技术研究综述

随着社会的发展,并联运动机床技术迅速成为数控领域中的一个研究热点,具有广泛的应用和广阔的发展前景。简要介绍了国内外并联运动机床的研究背景及其发展现状,对并联运动机床的关键技术即数控系统实时控制模型、位置正反解和运动学分析分别进行了介绍,并对目前存在的主要问题和解决方法进行了探讨。     

精密辊筒机数控系统开发

针对自主研发的精密辊筒机床,开发一套基于IPC和UMAC的开放式数控系统。依据精密辊筒数控机床的功能需求和结构特点,设计数控系统的硬件平台,搭建数控软件的总体框架,并采用模块化编程技术,基于Qt Creator编程环境开发数控系统软件,实现了轴信息显示、运动控制、自动编程和程序编辑等功能。进行微V形槽阵列加工实验,结果表明:该数控系统功能丰富,运行稳定,可以满足精密辊筒机床的数控加工要求。     

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。