基于ANSYS的砂轮架体及电主轴的静动态特性分析

文章以某型号曲轴随动磨床液体静压电主轴和砂轮架体为研究对象,运用软件SolidWorks对液体静压电主轴和砂轮架体进行几何建模,通过有限元分析软件ANSYS Workbench对液体静压电主轴和砂轮架体进行静动态特性分析,进而计算液体静压电主轴和砂轮架体在磨削力作用下的静力变形状况、在自由振动情况下的多阶固有频率和振型状况以及在激振力作用下的动力响应特征。分析结果表明砂轮架体及电主轴的设计满足技术要求。砂轮架体及电主轴的静动态特性分析对改进曲轴随动磨床结构、提高曲轴随动磨床的磨削效率、规避工作频率引起的振动、提高磨床的表面磨削质量等均具有重要的意义。     

高速磨削电主轴冷却系统的试验研究

高速磨削电主轴的温升对电主轴的加工精度和使用寿命有着重要的影响。以SPM170高速磨削电主轴为研究对象,采用理论分析和试验验证的方法对高速磨削电主轴的冷却系统进行了研究。通过分析可知电主轴电机部分的产热主要是由铁芯损耗产生的,水冷系统可以有效地带走电机部分的热量,使电主轴的温升降低。对SPM170高速磨削电主轴的冷却系统进行了改进,设计了一种新型螺旋水道,在电主轴最高工作转速时,分别测量电主轴前轴承壳体温度,并对比其温升。结果表明:采用改进之后的螺旋水冷装置电主轴的温升比改进前温升降低了10℃左右,温升得到了有效的控制。     

磨削电主轴动态回转精度分析及实验

以高速磨削电主轴为研究对象,对电主轴回转误差的表现形式、误差的分类进行分析。建立误差分离模型,提出利用最大波峰值减去最小波谷值的方法进行误差分离,并建立径向误差、倾斜误差和轴向误差运动的模型。通过最小二乘法平均值算法分析径向误差,基于径向误差轨迹分析得出倾斜误差。结合时域和频域的信号分析方法,对轴向误差进行分析。基于双标准球、多个高精度电容位移传感器和温度传感器组成的测量系统,在某国产磨削电主轴上进行动态回转误差测量实验。结果表明：随着转速升高,磨削电主轴的误差逐渐减小并趋于稳定;误差最小时其径向误差7.5 μm,轴向误差6.02 μm,倾斜误差25.91 μrad;在电主轴长时间运行过程中,随着温度升高其回转精度的变化并不明显,但是会出现热偏移的现象。     

插入式永磁同步电主轴无传感器弱磁控制技术研究

为了提高电主轴的电流利用率和鲁棒性,在矢量控制的基础上,对插入式永磁同步电主轴进行研究。对最大转矩电流比控制的四阶方程进行标幺化处理,采用拟合曲线的方式对方程进行近似求解;利用弱磁调速扩展主轴的速度范围。通过滑模观测器估算电主轴转速,为了改善传统滑模观测器的抖振问题,将Sigmoid函数引进传统滑模观测器中,通过李雅普诺夫判据对所提策略的稳定性进行推导说明。以实验室中高速磨削电主轴FL170-20-15为例,通过以上算法搭建基于MATLAB的仿真实验平台进行实验验证,并分析该控制策略的效果。实验结果表明：采用该方法的高速磨削电主轴减小了滑模观测的抖振现象,提高了控制系统的鲁棒性。     

成形法磨齿加工中切向磨削力的试验研究

选择不同的磨削用量,在YK73125数控成形砂轮磨齿机上进行了成形磨齿加工试验,对成形磨齿加工中的切向力进行了研究。通过测量不同磨削用量下的电主轴的功率,用角正回归法推导出了加工过程中切向磨削力的试验公式,并对其加以修正,继而得出了更加精确的试验公式。这一研究验证了角正回归法是研究金属切削过程的一种高精度的回归法,为进一步探讨磨削烧伤打下了基础。     

数控机床高速主轴单元动态特性仿真分析

对电主轴建立了较精确的三维有限元建模,经有限元计算分析,获得了电主轴的模态和谐响应特性,研究了电主轴的固有频率、振型和临界转速,对高转速条件下主轴前端及不同特征位置所发生的最大动态位移进行了分析计算,验证了主轴结构设计的合理性.     

数控机床法向磨削力的控制试验研究

通过测量内表面磨床SUU600A加工和空载时电主轴功率,计算砂轮所受切向磨削力;根据经验算法计算法向磨削力,分析砂轮线速度、进给量、磨削深度对法向磨削力的影响,总结法向磨削力变化趋势;提出一种基于模糊PID的数控磨削加工磨削力实时控制方法.结果表明:使用模糊PID磨削力控制系统加工时,可实现对磨削力实时修调,使它始终保...     

基于垂直两点法的电主轴回转精度分析

应用垂直两点法设计测试系统，对电主轴回转精度进行动态测量。该系统主要由标准棒、高精度非接触式电涡流传感器组成。通过建立误差分离数学模型，对垂直两点法测量电主轴回转精度进行分析，利用垂直两点法分离误差方法对实验数据进行处理，得到电主轴在不同转速下的回转精度，研究表明电主轴转速在10000 r/min以上时回转误差较小并趋于稳定，找出影响电主轴回转精度的因素并进行了归纳。对电主轴回转精度在线监测和转速控制提供了重要的理论、实验依据。     

超高速磨削电主轴热特性分析

为了探明超高速磨削电主轴的内部温度情况,以及各部分温升引起的部件变形,文章以内装同步电机电主轴为研究对象,分析了其热量传递过程,计算了电主轴电机定子和轴承的发热量及各部分对流换热数,并对其稳态温度场、瞬态温度场及热-结构耦合场进行了分析。分析结果表明电主轴内部温度分布是极不均匀的,前后轴承与定转子之间存在很大的温差,各部件不同的热膨胀量造成了主轴轴头部分的热变形,影响了电主轴的精度和稳定性。     

平面并联机构与电主轴耦合系统动态性能研究

并联机床的动态性能是影响其精度的主要因素之一,因此,必须从平面并联机构与电主轴耦合系统的角度出发,研究动力学参数变化对平面并联机床动态性能的影响.根据已建立的平面并联机构与电主轴耦合系统动力学模型,运用数值方法研究了动力学参数变化对耦合系统动态性能的影响.结果表明平面并联机构的动力学参数对耦合系统动态性能的影响占主导地位.相比较而言,电主轴的动力学参数对耦合系统的动态性能影响较小.因此,在提高平面并联机床的加工精度和动态性能时,应该着重考虑平面并联机构,适当地增大并联杆件的刚度和阻尼.     

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.     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.