170小型曲轴RR锻造工艺研究

针对小型曲轴结构特点,设计了170曲轴RR锻造成型工艺,采用有限元模拟与工艺试验分析了170曲轴锻造成型过程及其成型情况。结果表明,170小型曲轴锻造成型工艺方案可行。     

微车曲轴锻造工艺开发及模具设计

以微车内燃机用曲轴的成形工艺开发为目的,分析了该规格曲轴成形可行性及工艺难点,设计了预、终锻件形状及预、终锻模具结构.在预锻件平衡块的内侧设计了厚度为15mm的工艺连皮,预、终锻模具设置了阻力墙结构,上述两项工艺改进有效的保证了终锻件的成形效果.利用金属塑性成形仿真软件DE-FORM-3D,对改进的工艺进行仿真分析,仿真结果有效的验证了工艺方案.模拟预测了预、终锻成形力分别为39.9MN,终锻为56MN.设备63MN有富余.模拟显示终锻件的平衡块顶端完全充满.基于模拟验证的工艺和设计的模具进行生产试制,经检测曲轴锻件产品的尺寸及性能完全达到了设计要求.     

YC6C曲轴铁型覆砂工艺设计

针对YC6C船用曲轴的铸件结构,设计了铸件的铁型覆砂工艺.经铸造模拟分析并结合实际生产试制对铸造工艺进行了改进,得到了符合QT800-6性能要求的球墨铸铁曲轴,解决了球铁铸件缩松、表面质量等问题,为铁型覆砂工艺生产大型球铁铸件提供了成功经验.     

基于CAD/CAE技术的汽车曲轴模锻工艺优化

介绍了CAD/CAE技术在汽车曲轴模锻工艺中的应用,建立了曲轴模锻成形工艺的刚粘塑性有限元模型,采用三维有限元法对成形工艺进行了模拟分析,基于模拟分析结果,优化了曲轴模具结构,确定了合理的工艺流程.通过生产试制,验证了曲轴模锻工艺优化的合理性与可行性,为同类产品的生产提供了理论依据和技术支持.     

自循环曲轴镗床结构设计及控制

针对汽车、摩托车曲轴销孔的加工,设计一种五工位自循环曲轴镗床。设计自循环曲轴镗床的整体结构;根据曲轴销孔的加工工艺要求对定位夹紧装置和中心距微调机构等主要部件进行设计并分析;对自循环曲轴镗床的加工工作循环和控制系统进行设计,并给出程序控制流程。该曲轴镗床的成功应用表明其设计的合理性。     

球墨铸铁曲轴的铸造及热处理工艺

针对高性能球墨铸铁曲轴整体对开、平面分型工艺易出现夹砂、气孔等铸造缺陷的问题,重新设计了铸造工艺,采用曲面分型,配以凸凹模板,设计了无芯铸造曲轴分型工艺,简化了操作工序,避免了夹砂、气孔等铸造缺陷的产生,降低了生产成本.为使铸件组织均匀,研制出了曲轴自动连续冷却生产线以及悬挂式旋转风雾冷却装置,均匀冷却后工件的热应力和组织应力分布均匀,减少了工件变形,提高了曲轴的质量,改善了曲轴的性能,实现了多缸曲轴的批量稳定生产.     

汽车发动机曲轴及其焊接修复技术研究

曲轴是汽车发动机系统的关键零部件,首先通过对汽车发动机曲轴的功能重要性、结构特殊性以及工作原理进行分析,突出了曲轴在汽车安全行驶过程中的关键性与重要性,然后简要概述了汽车发动机曲轴的装置结构及其生产加工特点,紧接着从焊接修复方法的选择、焊条的性质、焊接修复工艺措施三个方面分析了曲轴焊接修复工艺设计,最后从曲轴焊接修复前五项准备工作和焊接修复过程六项重点工作,详细介绍了曲轴焊接修复过程实施细节及关键控制点,对同类结构件焊接修复具有重要参考意义。     

大偏心量重载的组合式曲轴及其弹性支撑方式的探讨

本文对曲轴的四种弹性支撑方式进行了有限元分析,得到了支撑轴套分别采用四种不同支撑材料的曲轴及弹性支撑的最大应力和应变。以630 k N曲柄压力机所使用的曲轴为例,采用Pro/e软件设计并建立了整体式曲轴、组装式曲轴和部分组装式曲轴在刚性支撑时的三维模型。采用ANSYS软件分别对三种曲轴结构进行了有限元分析,得到了三种曲轴结构的最大应力和应变。从制造工艺、与连杆装配、最大应力和应变等方面对三种曲轴进行了分析对比,为以后曲轴的设计提供参考依据。     

曲轴在对击锤上的模锻

分析了KV12曲轴的结构特点和其在1MJ对击锤上模锻的工艺过程,提出了大型曲轴锻模的新的设计参数,为大型模锻锻模的制造和使用提供了可借鉴的生产实践经验。     

大功率柴油机KV_(12)曲轴在1MJ对击锤上的模锻

本文对KV12曲轴的结构特点和在1MJ对击锤上模锻的工艺过程进行了分析。对大型曲轴模具提出了新的设计参数,为大型模具制造和使用提供了可借鉴的生产经验。     

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。