花键离合齿轮镦挤复合成形

对花键离合齿轮外形尺寸进行了工艺分析，选择镦挤复合成形工艺，制订了零件冷挤压件图及镦挤工艺流程，对镦挤变形程度进行校核，计算了最大挤压吨位，并介绍了镦挤模具的结构特点。     

活塞销冷挤压工艺及模具设计

通过对２０Ｃｒ 冷挤直通孔活塞销坯料的表面润滑处理及成形工艺的分析，设计出合理的工艺路线及冷挤成形模具结构。并在模具凸模制造工艺中，运用气体氮碳共渗处理工艺，有效地提高了模具寿命，使直通孔活塞销的冷挤压成形工艺在大批量生产中变得经济可行     

铜管接头冷挤镦工艺及模具设计

文中指出了采用冷挤镦工艺代替切削加工生产铜管接头的优点。对铜管接头进行冷挤镦工艺分析、制订冷挤镦件图计算毛坯尺寸及冷挤压镦力。介绍了管坯制备处理及冷挤镦模具结构设计。     

基于Deform的换向器座冷镦挤模具优化

利用Deform软件模拟不同模具圆角半径的冷镦挤成形,分析不同模具圆角半径在镦挤过程的载荷-行程曲线、等效应力、等效应变及金属流动速度的影响规律.通过64组镦挤过程的模拟数据表明,对于换向器座类零件冷挤压成形,当凸模圆角R1取3mn、R2取0mm,凹模工作区域顶端圆角半径R3取3 mm时,镦挤成形所需的载荷达最小值.     

夹头冷挤模设计

论述了夹头冷挤压成形工艺、毛坯制备和模具设计要点，给出了实用的模具结构。     

浅析肘杆式冷挤压力机的发热问题

１　前言冷挤压力机适用于各种毛坯、锻件的冷挤压成形及平面精整等冷冲工艺。由于冷挤压产品切削量少，成本低，且生产效率高，所以广泛地应用于汽车、轴承、家用电器、五金等行业。随着冷挤压工艺的发展成熟，也使相应的冷挤压力机不断更新完善。适合于冷挤压工艺的肘杆式压力机，就提供了理想的冷挤压工艺的速度曲线和力学特性。冷挤压工件比较小，工作台面也不大，但所需工艺力却很大，铜瓦的比压都很高，往往会产生大量的热，影响压力机的使用性能和寿命。因此，如何减少发热成了影响冷挤压力机使用性能的首要问题。下面就笔者在工作中…     

中轴挤方加工工艺的研究

通过对D型中轴两端挤方加工工艺进行分析,介绍了零件的工艺力计算,同时介绍了模具结构及模具的工作过程,给出了挤方块和模套的设计方法,保证了该零件挤方成形的顺利进行.     

两端面具有凸块的齿轮锻件温挤成形工艺设计

以某90型摩托车变速箱中的花键主动齿轮锻件为例,依据温挤成形技术原理,对复杂形状齿轮锻件进行了锻件分析和温挤成形工艺分析,阐述了复杂形状齿轮锻件温挤成形工艺设计中的难点与关键点,并结合生产实际,制定了适合生产实际的温挤成形工艺。设计了一套经济实用的温挤成形模具,同时介绍了模具结构和工件原理。经批量生产试制证明,该温挤成形工艺生产的齿轮锻件质量稳定、凸块饱满,且模具结构合理、通用性强、生产效率高。     

汽阀弹簧座镦挤复合成形工艺的分析

国内在采用冷挤压工艺生产汽阀弹簧座方面,已经取得了许多宝贵的经验。对于这种中心成锥形孔、外趋为多台阶类型的零件,普遍采用的成形工艺为车削加工棒料或管料成环形毛坯,然后进行镦挤成形。为了进一步发挥冷挤压工艺高效率低消耗的特点,制订两个工艺方案进行试制,最后采用剪切棒料镦挤成形的工艺,并经过批量试制,目前正式投入生产。一、工艺分析     

渐开线花键轴无屑加工研究

介绍了渐开线花键轴无屑加工(冷挤压工艺),对冷挤压的成形原理、工艺分析、毛坯设计、模具及重要型腔的设计进行了阐述.结果表明:渐开线花键轴采用冷挤工艺可行,产品质量好,生产效率高,产品成本低.这能为类似零件的加工工艺提供参考.     

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.     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.