基于PMAC快速PID整定与精度补偿研究

数控系统中动态性能与定位精度决定了加工质量及效率,为满足磨床数控系统控制要求及加工精度,研究快速整定PID方法及提高定位精度补偿方式,基于PMAC运动控制器搭建五轴数控工具磨床的全闭环伺服系统。针对伺服系统动态性能差、跟随误差较大等问题,阐述了基于PMAC的前馈-PID陷波滤波器伺服算法,提出了快速PID整定方法。针对定位精度差的问题,论述了定位补偿原理及方式,使用激光干涉仪进行目标点测量后制作螺距补偿和反向间隙补偿表。结果表明,PID整定方法得当,五轴磨床的动态响应性能良好,跟随误差大幅度减小;定位补偿措施合理,定位精度和重复定位精度大幅度提高,达到设计要求的3μm以内。     

基于Cortex-M4的环面蜗杆检测仪的全闭环控制系统（英文）

针对环面蜗杆检测仪系统控制及定位精度的需要,采用Cortex-M4作为主控制器,控制步进电机驱动载物台运动,步进电机采用闭环控制。光栅尺实时检测XYZ导轨的位置信息,并把光栅信号作为反馈信号,构成闭环运动控制系统,实现坐标系中XYZ轴的运动和时栅转台旋转的高精度定位。步进电机的驱动采用软硬件细分方法,克服了步进电机爬行和丢步现象。实验表明:该系统采用全闭环控制、步进电机软硬件细分方法,实现了三坐标轴±2μm的精密定位,保证了环面蜗杆检测仪的准确测量。     

基于Cortex-M4的环面蜗杆检测仪的全闭环控制系统

针对环面蜗杆检测仪系统控制及定位精度的需要,采用Cortex M4作为主控制器,控制步进电机驱动载物台运动,步进电机采用闭环控制。光栅尺实时检测XYZ导轨的位置信息,并把光栅信号作为反馈信号,构成闭环运动控制系统,实现坐标系中XYZ轴的运动和时栅转台旋转的高精度定位。步进电机的驱动采用软硬件细分方法,克服了步进电机爬行和丢步现象。实验表明：该系统采用全闭环控制、步进电机软硬件细分方法,实现了三坐标轴±2 μm 的精密定位,保证了环面蜗杆检测仪的准确测量。     

微电机轴球面成型加工方法的探讨

微电机轴端设计成R球面是减小电机振动和噪声的一种重要方法.为了提高微电机轴端R球面的加工效率,从微电机轴端R球面加工的相对运动关系入手,对微电机轴球面的磨削成型方法进行探讨,分析嵌件轮、工件和砂轮的运动关系,导出成型砂轮的砂轮形线的数学模型.为微电机轴球面的加工工艺建立和成型设备制造提供参考.     

面向芯片封装的冗余驱动T型XY运动系统的研制

面向芯片封装设备对高速高精度的需求,提出了一种多直线电机冗余驱动的T型XY运动系统.T型XY工作台以单直线电机作为Y轴动力源,双直线电机作为X轴动力源,并配以高分辨率、高精度的位置检测元件和控制系统,共同组成T型运动系统.叠加式的机械结构设计使得工作台尺寸小、质量轻、刚度高;多电机的冗余驱动为系统提供了更大推力以提高设备的加速度.通过扫频试验,建立了系统的实验模型,在实验模型基础上设计了控制器并进行了实验研究.该运动系统目前实现了最大速度0.65m/s,最大加速度9.25g,及微米级定位精度的性能指标,能够适应当前IC封装业发展对高速高精度的要求.     

基于PMAC运动控制卡的六自由度运动平台控制系统开发

通过研究典型Stewart运动平台相关理论,成功研发一台六自由度运动平台样机并进行了相关运动控制试验。该样机采用美国Delta Tau公司的PMAC运动控制卡控制6个步进电机带动的电动推杆实现对运动平台6个驱动杆的伸缩控制,从而达到控制运动平台姿态的目的。     

PMAC多轴运动控制器应用研究

本文通过对PMAC多轴运动控制器应用方案的论述，介绍了利用PMAC构建一个机电一体化实验装置所需要的软硬件结构，以及构建系统的方法、解决手段和需要注意的事项。     

基于PMAC的数控铣齿机双电机消隙技术研究

螺旋锥齿轮铣齿机在数控加工过程中经常出现冲击和振荡等现象,严重影响齿轮加工精度。研究发现伺服传动系统中存在的齿隙非线性问题对铣齿机的加工精度、可靠性和稳定性有较大影响。通过比较消除齿隙方法,提出一种基于PMAC运动控制器的铣齿机传动系统双电机消隙方法。对双电机消隙的基本原理以及消除间隙的过程进行分析,并且根据双电机消隙原理设计试验流程;搭建基于“IPC+PMAC运动控制器”的双电机驱动应用系统,并在PMAC IDE中进行相关配置;最后基于上、下位机结构配置的数控系统试验装置,进行试验验证。试验结果表明：所提方法能够有效抑制齿隙非线性的干扰、提高系统的稳定性,证明所提双电机伺服消隙方案的可靠性。     

基于IPC+PMAC的全自动汽车车牌压字机控制系统

针对国内车牌压字机存在自动化程度差、生产效率低和定位精度不高等问题,设计一种以IPC+PMAC为核心的汽车车牌自动压字机控制系统。采用IPC和PMAC控制字模库,实现对车牌字模的组合排序。利用PLC控制步进电机、气缸等完成车牌的上下料;由液压缸对车牌进行冲压,完成车牌的自动化压字。实验结果表明：该系统能够实现车牌的全自动化压字,提高车牌生产效率,降低生产成本,可为设计新型的汽车车牌压字机提供参考     

快走丝复杂曲面线切割伺服系统设计

采用工件运动的方式进行复杂曲面线切割加工是个很好的选择,而对工件的三维空间定位伺服机构的精确控制是进行零件加工的关键.以研制的三轴联动高精度数控转摆摆工作台为基础,提出了基于多轴运动控制器(PMAC)的五轴联动线切割机床伺服控制系统.介绍了机床的总体结构和PMAC卡的PID控制算法.控制环节采用底层开发的开放伺服PID控制策略,利用PMAC TURNING软件对转摆摆工作台各轴的PID参数进行了调节并获得了合理数据.试验表明工作台获得了较好的稳态特性和动态特性,实现了工作台的精确位置伺服控制.为实现高精度复杂曲面线切割加工提供了有力支持.也为研制复杂曲面电火花线切割智能制造系统奠定了基础.     

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.     

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。     

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.     

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.     

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).     

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.