升降器外壳冲压工艺设计

传统升降器外壳冲压工艺存在冲压工序多,制造成本高等缺点,为了克服这些缺点,分析了汽车车门某外壳件冲压工艺,研究比较了5种工艺方案.根据翻边工艺计算翻边系数K,计算分析拉深次数.提出升降器外壳件新冲压工艺设计,采用新工艺,取得了良好效果.     

汽车后安全带固定座冲压模拟及模具设计

分析计算了汽车后安全带固定座的冲压工艺,确定了落料冲孔翻边复合模冲压方案。利用DYNAFORM软件得到了制件翻边前的落料形状并模拟了制件翻边成形过程,验证了落料冲孔翻边复合模冲压加工的可行性。设计了1副落料冲孔翻边复合模,并阐述了模具结构、工作过程及设计制造要点。生产实践表明,该模具能够一次完成落料、冲孔、翻边工序,操作方便可靠,保证了制件的形状和精度。     

端盖落料拉深冲孔翻边局部成形复合模设计

分析了端盖的冲压工艺,设计了落料—拉深—冲孔—翻边—局部成形复合模,详细阐述了模具结构、工作过程及设计技巧。实践表明,模具能实现一次完成落料、冲孔、拉深、翻边、局部胀形工序,保证了产品的形状和尺寸精度。     

筒形件冲压工艺分析及模具设计

分析了某筒形件的冲压工艺,在原成形方案的基础上将落料与拉深工序复合、胀形与冲孔工序复合,节省了1副模具,并介绍了工件胀形、冲孔分步式复合模的结构及主要零件的设计。实践证明,该模具结构合理,生产的工件满足使用要求。     

防尘罩冲压工艺分析及复合模设计

分析了防尘罩冲压成形的工艺特点,制定了冲压方案。设计了一套落料、冲孔、拉深、翻边、压筋复合模,介绍了模具的工作原理,对设计要点进行了详细的说明。该模具结构紧凑,可靠性好,对同类零件模具的设计具有一定的参考价值。     

外壳冲压件成形工艺分析与模具设计

为了保证弯曲时外壳零件多孔的形状,并降低模具的设计成本,通过对冲压工艺分析,对比不同工艺方案,设计了冲孔落料复合模与单工序弯曲模来实现零件的成形。冲孔落料复合模可一次实现多孔成形,保证多孔分布的均匀性及成形的高效性;弯曲模易于确定压力中心,可确保零件一次弯曲成形。该套模具可提高外壳冲压件的生产效率,保证产品质量。     

锁扣安装架多工步成形工艺数值模拟及参数优化

锁扣安装架为复杂的弯曲件之一,按照冲孔落料、两侧翻边、弯曲的成形工艺易在拐角处产生裂纹,无法满足成形质量要求。而采用冲孔落料、翻边、弯曲、翻边的成形工艺,不会在拐角处产生裂纹。通过有限元软件对两种成形方案进行多工步成形工艺数值模拟分析,比较了两种成形工艺方案所得零件的质量,选定压料力、模具间隙、冲压速度为影响因素,采用正交试验设计,通过有限元软件进行模拟分析,以零件的减薄率作为评价标准,确定了最优的工艺参数组合,并通过试验验证了多工步成形工艺路线的可行性。     

滤网框结构优化与模具设计

分析了滤网框原结构与改进后的结构,将原翻边结构改进为低盒型件结构。对新结构进行了冲压工艺分析,设计了落料拉深复合模,介绍了其结构与工作过程。实践证明,滤网框结构和冲压工艺改进后,明显提高了零件的结构强度,减少了成形工序,降低了成本。     

上盖冲压工艺与模具设计

根据某上盖零件的结构特点及技术要求,通过对各工艺方案进行分析比较,设计了落料-拉深-冲孔-翻边复合模,即在一个工位同时完成落料、拉深、冲孔和翻边4个不同工序的复合模结构.详细介绍了模具的工作过程及设计要点,解决了条料的定位、导向、卸料、出件、优化模具结构等技术问题.经实际生产验证,此套模具大大提高了生产效率,其合理的模具结构保证了上盖的形状及尺寸精度,提高了企业的经济效益.     

汽车座椅对称件冲压成形仿真设计及优化

为了解决高强度钢作为汽车零件材料在冲压成形过程中存在的成形缺陷,以某品牌汽车座椅的调角器边板为例,针对其几何结构和对称件的特征进行了冲压工艺流程设计及优化、零件成形精度优化。首先,确定零件的冲压工序,根据其结构特点将冲孔工序的工作内容与其他工序合并,合理减少总工序数,并一次对两个零件同时进行冲压,优化后的冲压工艺流程为：落料、拉深、修边、翻边。然后,通过调整压边力、摩擦因数和拉深模具间隙3个工艺参数对零件的成形精度进行优化,降低其回弹量,使零件满足实际尺寸精度要求,优化后的工艺参数组合为压边力为33 kN、摩擦因数为0.13、拉深模具间隙为2.70 mm,仿真结果中零件的最大回弹量为1.264 mm。最后,进行样件试冲,零件实际的最大回弹量为1.270 mm,与仿真结果基本一致,验证了仿真结果的有效性。     

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.     

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.