簿壁壳体零件加工工艺及夹具设计

分析簿壁壳体零件特点和加工难点。设计车加工夹具,解决车加工变形问题;设计钻孔夹具,利用夹具精度,保证零件加工精度。通过设计工装夹具,解决了簿壁零件变形问题。     

PCB电路印刷基板卡位数控加工夹具设计

对非金属PCB电路印刷基板卡位的加工工艺进行了分析,设计一副专用夹具,解决了工件装夹定位问题,并在加工使用过程中根据实际情况进行了夹具的优化改进,使夹具能简单、快捷、安全地安装在机床上,提高了夹具的稳定性,保证了工件的加工精度,节省了夹具制造成本。     

基于模态分析的高精密夹具优化设计

针对发动机G415缸体需精密铣削顶面以及面上面相关孔加工,设计高精密专用夹具。为使高精密夹具系统具有良好的抗振性能,建立夹具工件系统的三维模型,并用ANSYS Workbench对设计的夹具进行模态分析。为防止切削加工中产生切削震颤,分析出影响夹具模态的关键结构,并对其进行改进。改进后夹具的固有频率跳过了机床临界加工频率,避免了共振的产生,为高精密夹具设计制造和机床加工质量的提高提供了理论依据。     

弯管接头车床加工螺纹夹具设计

通过设计使用简单的夹具,解决了加工中的问题,提高了加工效率。利用零件本身的弯管部位和夹具上孔构成轴孔定位,利用零件本身的孔与夹具上削边销构成销孔定位,通过夹具使零件回转中心与车床回转中心重合,实现切削条件。夹具制造成本低,使用方便,有效保证了加工质量。     

非圆柱表面的夹具设计

分析活塞压缩机非圆柱表面加工方法的优、缺点.依据型面加工原理,设计了加工非圆柱表面的夹具.使用该夹具无需对普通车床进行改装就可实现非圆柱表面的加工,且加工精度高.并给出了使用该夹具加工非圆柱面时的误差计算公式.     

长连接板双面钻孔夹具设计

分析了加长连接板的特点、加工工艺、如何提高加工效率并保证加工精度,重点介绍了双面钻孔夹具的设计过程,夹具的结构用角钢做钻模板本体,使用弓形卡做夹紧支撑,最后介绍了该夹具的使用过程。     

基于PMC的连杆零件数控机床自动夹具设计与实现

为减小多次定位装夹引起的定位误差对零件加工精度影响,通过对连杆零件加工工艺分析,提出以零件不需加工的设计基准面为定位基准,以数控机床自身气源为动力、PMC为控制装置的工序集中式自动夹具设计理念。经设计夹具结构、气动系统和控制系统等,完成了基于PMC的连杆零件数控机床自动夹具制作。该夹具结构简单、定位准确、夹紧可靠、稳定性好。实验证明:利用该夹具加工连杆零件,连杆零件加工表面相互位置精度得到了一定程度的提高。     

基于多体系统理论的榫卯加工中心夹具系统精度建模分析

针对榫卯加工中心加工过程中出现加工误差大的现象,分析造成误差的主要误差源是夹具系统。榫卯加工中心的夹具系统采用螺栓定位,较大影响了整个夹具系统的装配精度,对整体加工造成较大的加工误差。根据该夹具系统的机械结构及其连接方式,提出基于多体系统运动学理论和齐次变换的方法,建立榫卯加工中心夹具系统的误差模型,并推导了考虑装配误差的最终误差公式。针对运用螺栓定位造成的加工缺陷,并考虑夹具系统的特殊性,提出了一种夹具系统改进方案,并利用多体系统运动学理论建立误差模型,为提高榫卯加工中心加工精度提供理论依据。     

一种高效铣削弹性夹具设计与应用

为了加工一种具有特殊结构的汽车用高度调整销,解决加工时零件对称平面的对称性与平行性问题,设计了一种可一次装夹多件零件的弹性夹具。通过对夹具的结构设计与夹紧力分析,充分保证了夹具装夹的可靠性与高效性。实践证明,该夹具的使用提高了零件的加工效率,同时降低了零件的废品率。     

摩托车曲轴箱油道孔钻铰加工专用夹具设计

右曲轴箱是摩托车上的一个重要零件,其加工质量的好坏直接影响发动机性能和整车质量,该零件的油道孔加工要求较高.针对某右曲轴箱加工油道孔比较困难,文章分析了曲轴箱的结构特点及加工工艺,设计出简单易用的钻、铰复合加工专用夹具.介绍了该夹具的结构及工作原理、夹具的特点及夹紧力,采用此夹具加工右曲轴提高了生产效率,同时也节约了生产成本.     

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。