高速主轴油雾润滑的关键问题研究

通过对高速机床主轴的工况条件及润滑关键问题的分析,设计一种适用于其主轴的油雾润滑系统,即润滑油在压缩空气驱动下,经过油雾发生器形成饱和油雾,喷射至轴承表面形成润滑油膜以达到润滑的目的.该油雾润滑系统具有润滑效果好、耗油量少、散热性好、成本及维修费用低以及便于集中管理等特点,能显著提高滚动轴承极限转速.     

基于刀具内冷孔喷射的MQL流量控制研究

微量润滑技术(MQL)越来越普及,而流量控制及油雾排放情况也成为研究重点。提取某机床5年以来微量润滑的用油量及排放效果,分析MQL流量控制的方法和混配比例,总结出各种切削条件下切削油用量标准。     

超声振动钻削皮质骨切削区温度的研究

为了直观明了地分析骨钻削过程中切削区的温度,把三维钻削问题转化为二维切削问题,建立了二维正交切削模型;分析骨钻削过程中第三变形区温度的变化,并利用ABAQUS软件建立超声振动正交切削有限元仿真模型,通过试验验证了仿真模型的正确性;然后通过仿真模型,对比分析普通钻削与超声振动钻削的第三变形区温度变化,并进一步分析了超声振动条件下,转速对皮质骨第三变形区温度的影响。结果表明:相比于普通钻削,超声振动钻削能显著降低第三变形区的温度;随着转速的增加,第三变形区温度增加。     

麻花钻几何参数对不锈钢钻削性能影响的研究

采用ProE和Deform-3D软件分析了影响麻花钻钻411性能关健的几何参数,主要研究麻花钻横刃和顶角对不锈钢钻削过程中切削力、扭矩、刀具磨损的影响.介绍了缩短横刃长度和采用S形横刃螺旋面钻尖对不锈钢钻削力和扭矩的影响.重点分析了顶角影响主切削刃的长度、单位刃长的切削负荷、切削层中切削宽度与切削厚度的比例、切削中轴向力与扭矩、切屑形成与排屑情况.对于在钻削中,如何提高钻头的寿命,提高钻削加工的生产率和孔的加工质量具有重要的指导意义.     

微量油膜附水滴绿色加工技术的研究

通过微量油膜附水滴切削液、干切削和乳化液的对比试验,研究微量油膜附水滴的切削效果。试验结果表明:与干切削和乳化液润滑比较,采用微量油膜附水滴不仅能够降低切削力,而且还能降低刀具的磨损。     

磁控溅射CrTiAlN涂层钻头的制备及其钻削性能研究

通过利用磁控溅射离子镀技术制备CrTiAlN梯度涂层M2高速钢麻花钻,对镀层进行了组织、结构分析,并在干式切削条件下对普通45#钢和30CrMnSiA高强度钢进行了钻削试验.由于CrTiAlN涂层本身具有良好的热氧化性能和良好的组织结构,M2高速钢刀具经CrTiAlN涂层后,在干式切削条件下钻削45#钢和30CrMnSiA高强度钢时,钻头寿命比未涂层提高约19倍和15.2倍.     

B4C增强铝基复合材料钻削温度的非接触测量和多目标分析（英文）

采用光学高温计对在不同钻削条件下的B4C金属基复合材料的钻削温度进行非接触测量。研究了颗粒含量、切削速度、进给速率和刀具材料对最高钻削温度的影响。基于最高切削温度和刀具磨损对钻削参数进行优化。结果表明:对最高切削温度影响最大的因素主要为颗粒含量、进给速率以及切削速率与颗粒含量间的相互作用。切削速率与切削材料对最高切削温度的影响相对较小。当颗粒含量较小,切削速度较低,进给速率较高,利用硬质合金刀具时,切削温度较低。采用优化后的钻削参数可以获得较低的切削温度和较小的刀具磨损。     

枪钻在深孔加工中的应用

根据对枪钻磨损要因图的分析,介绍了在发动机缸盖主油道孔加工过程中影响枪钻寿命的主要工艺因素,枪钻在深孔钻削时最主要的问题是断屑和排屑。针对这些问题,对切削刃几何形状、几何参数和钻削参数进行了分析和改进。应用结果表明:改进后断屑效果较好,切屑能够顺利排出,刀具寿命和切削效率大大增加。     

B_4C增强铝基复合材料钻削温度的非接触测量和多目标分析(英文)

采用光学高温计对在不同钻削条件下的B4C金属基复合材料的钻削温度进行非接触测量。研究了颗粒含量、切削速度、进给速率和刀具材料对最高钻削温度的影响。基于最高切削温度和刀具磨损对钻削参数进行优化。结果表明:对最高切削温度影响最大的因素主要为颗粒含量、进给速率以及切削速率与颗粒含量间的相互作用。切削速率与切削材料对最高切削温度的影响相对较小。当颗粒含量较小,切削速度较低,进给速率较高,利用硬质合金刀具时,切削温度较低。采用优化后的钻削参数可以获得较低的切削温度和较小的刀具磨损。     

基于MQL的碳纤维复合材料制孔表面质量及切削力试验

目的 减少碳纤维增强复合材料(CFRP)制孔表面毛刺及边缘凸起等缺陷。方法 对比研究在干切削和微量润滑(MQL)2种加工条件下碳纤维增强复合材料(CFRP)的制孔,在切削速度一定时,探究切削方式、进给速度对制孔尺寸精度、表面质量、切削力的影响。采用方差分析对各影响因素及其权重进行分析。结果 得出了切削方式和工艺参数对制孔尺寸精度、切削力、表面质量的影响规律。试验结果表明,在微量润滑条件下,由于润滑和降温的影响,表面毛刺得到有效去除,纤维断面平整,剪切作用明显,抑制了由温升所引起的边缘隆起膨胀现象,试样的表面质量得到显著提高,切削力整体降低。在干切削和微量润滑条件下对制孔尺寸精度影响最大的是切削方式。对于切削力,在干切削时受到切削方式的影响最大,在微量润滑条件下受到进给速度的影响最大,随着进给速度的增大而增大。结论 在现有试验条件下,微量润滑的加工质量总体上优于干切削的加工质量,其制孔尺寸的精度整体更高,其切削力最大降低了84.26%。     

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).     

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.     

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.     

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。