车架纵梁冲孔模装配调试

分析了车架纵梁冲孔模结构,提出了特大型模具装配调试的难点,在模具生产中没有调试模具用的大型冲压设备情况下,结合模具结构和生产设备的现状,提出了可行、较简便的调模工艺方法,解决了特大型冲孔模的装配调试难点。     

精密垫圈落料冲孔复合模加工及装配

通过对精密垫圈冲孔落料工艺的分析,介绍了模具关键零件加工工艺的特点.根据垫圈零件的特点,提出了采用倒装复合模工艺,介绍了模具结构,同时对模具装配的关键过程作了介绍.     

簧片冲压成形分析与模具结构创新设计

通过对簧片冲压成形工艺的分析,制订了模具整体结构及排样设计方案.针对簧片结构中的小孔特征,其冲孔凸模在冲压加工中磨损较快,为实现冲孔凸模的快速换修和装配,设计了一种冲压凸模装置——卡槽式快换凸模.采用该结构的凸模既可保证成形产品的表面质量,又显著降低了生产成本,提高了冲压生产效率,尤其适用于凸模形状复杂、局部薄弱、需要经常维修、更换的连续冲压模具,具有很好的应用前景和实际意义.     

复合模的装配

<正> 装配是模具制造的最后工序,其质量的优劣不但影响模具的合格与否,而且关系到它的使用寿命。复合模装配的关键是间隙的调整。以落料冲孔式复合模为例,不论是正装式还是倒装式,都存在着保证两方面间隙的问题,往往是顾了冲孔间隙而落料间隙不能保证,尤其是在冲孔凸模较多且形状复杂的情况下,往往是顾此失彼。钳工装配合模     

安装板多工位级进模设计

在对安装板冲孔、弯曲、落料等成形工艺分析的基础上,提出了该零件采用多工位级进模的冲压方案,并介绍了该零件的工步、模具结构及模具加工。多工位级进模从模具结构上可实现快速更换下模镶件和大部分的凸模,提高了模具的重复装配精度。实践表明该模具结构灵活、可靠,达到了操作快捷、高效,降低了生产成本,并能保证产品质量。     

曲面冲孔模具结构对凸模寿命影响

曲面上冲孔一直是冲压工艺的难点,以热水器水桶固定架为案例,对在曲面上冲孔出现的冲孔凸模寿命短的问题进行了分析,对生产中使用的模具结构进行研究,找出影响凸模寿命的原因;根据热水器水桶固定架工件结构特点,优化设计了冲孔切边模.通过生产证明,此模具结构不仅提高了凸模寿命,还提高了工件质量.     

薄壁钢管冲孔模

通过对连接管冲孔工艺进行分析,介绍了各种加工工艺的特点.根据该零件特点,提出了采用有凹模冲孔加工,并介绍了模具结构及工作过程,同时对模具结构设计作了介绍.     

在线辊式冲孔模具的设计与模拟研究

在线辊式冲孔是一种应冷弯生产线高速冲孔要求而发展起来的新工艺.所开发的新型辊冲设备采用钢质凸模配对聚氨酯凹模的新型模具结构,能够完成厚度小于1mm低碳钢薄带的高速连续冲孔.在模具开发过程中,采用Deform 3D有限元软件对聚氨酯冲孔工艺过程进行了全面的数值模拟,并对冲头设计方案进行了优化分析.经计算机仿真分析和试验验...     

骑式摩托车后减震器支承板冲孔工艺与模具设计

骑式摩托车后减震支承板冲孔模具采用浮动式凹模,具有工艺简单、模具成本与维修费用低、操作方便快捷,制件质量和生产效率高等优点。分析冲孔工艺,并设计了冲孔模具,提供冲孔凸模和浮动凹模等工作零件的图形与尺寸,对同类冲压件具有借鉴意义。     

冰箱防护板冲孔模设计

介绍了防护板的结构特点 ,多孔冲模以及斜面冲孔模具的设计要点 ,并对斜面冲孔结构做了一定的改进 ,使模具的使用寿命和可靠性大大提高 ;加工精度的控制和保证 ,装配技术的改进 ,从而大大缩短了模具装配时间和制造周期。     

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.     

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.