汽车盘毂精密锻造工艺仿真研究

汽车盘毂是汽车离合器总成的重要组成零件,要求具有高强、高韧、耐冲击、抗疲劳等综合力学性能。传统的生产工艺由自由锻制坯和机械加工生产,产品力学性能及材料利用率较低,且生产中煤炭炉加热能耗巨大,污染严重。本公司与太原科技大学机械工程学院进行产学研合作,提出汽车盘毂零件的精密闭式模锻成形工艺,并对成形工艺进行计算机仿真计算,通过理论分析和模拟,提出合理的锻造工艺;分析了零件精密闭式模锻变形过程的载荷变化规律、温度变化规律和摩擦系数对零件成形的影响,进一步修正了零件精密闭式模锻工艺。     

热锻件冷锻工艺的应用及发展

叙述了冷锻工艺的方法及其发展过程，介绍了冷锻设备，例举了典型的法兰轴套，齿轮，凸缘轮毂及长轴零件的冷锻工艺，阐述了用冷锻工艺代替热模锻的优点。     

摩托车超越离合器本体的精密锻造工艺研究

通过中间预制坯形状和尺寸的合理设计、采用合适的冷挤压模具结构,用温/冷复合成形工艺进行了摩托车超越离合器本体内孔型腔的精密成形.采用该工艺生产的超越离合器本体精锻件,其内孔型腔不仅表面光洁度高、尺寸精度高,而且内孔型腔不再后续机械加工就可以达到超越离合器本体的设计要求,因此具有显著的节能、节材效果,经济效益十分显著.从1996年至今500万余件的生产实践表明,采用冷/温复合成形工艺是生产摩托车超越离合器本体的一种高效加工工艺.     

超越离合器壳体的冷挤压成形加工技术

超越离合器壳体是一种具有复杂内孔型腔的盘状类零件,其异型型腔的加工非常困难。通过控制金属流动,采用合适的凸模结构及合理的坯料形状,对离合器壳体内孔型腔进行了冷挤压成形加工。与传统的切削加工工艺相比,采用冷挤压工艺生产的离合器壳体内孔型腔不仅表面光洁度高、尺寸精度高、尺寸一致性好,而且内孔型腔不再后续机械加工就能满足离合器壳体的设计要求;同时还能够节约材料15%～25%、提高生产效率10～15倍。     

转向螺杆的挤压成形工艺研究

转向螺杆切削加工困难,材料利用率低.采用热模锻制坯后再进行机加工,其材料利用率和生产率有所提高,但质量和数量仍不能满足要求.为进一步提高生产效率,净成形内花键,采用了冷挤压成形工艺.转向螺杆的冷挤压凸模渐开线花键线切割加工后,经研磨抛光,然后以齿形面为基准配磨固定套,保证了挤压模具同心,从而保证了挤压件内腔的同心度.在挤压过程中,采用一种新型的水基高分子润滑剂,对软化退火后的20CrMnTi钢转向螺杆毛坯进行润滑,使得冷挤压件的内花键充满良好,避免了微裂纹产生,内花键及小孔无需再进行机加工,达到了零件图样的设计要求.经检测、加工、装机调试,采用该工艺冷挤压成形的转向螺杆质量好、精度高、满足零件的使用要求.     

奥氏体不锈钢管坯镦挤法兰工艺

针对应用广泛的奥氏体不锈钢中间带大孔的高颈法兰类零件传统锻造工艺的不足,提出了一种利用管坯直接镦挤法兰的新工艺;用DEFORM-3D软件模拟了奥氏体不锈钢(0Cr18Ni9)法兰锻件的管坯镦挤成形过程.结果表明:该工艺是可行的,与传统工艺相比,该工艺工序少,材料利用率高,成形载荷小,提高了生产效率,降低了生产成本.对类似零件的成形具有一定的参考价值.     

双动曲柄热模锻压力机上的热挤工艺

双动曲柄热模锻压力机上的热挤工艺２５００１４山东工业大学陈庄对于周边带有法兰、筋板、突部和中空轮毂等的小型锻件，左双动曲柄热模锻压力机上进行热挤压工艺有明显的技术经济效益。图１为摩托车变速器换挡齿轮在双动曲柄热模锻压力机上热挤的示意图。带有型腔的下模...     

套筒件的变薄拉伸工艺

发展和采用生产率高、节省原材料的制造工艺对国民经济的发展具有积极意义,几乎全部冷成形工艺均属此列。民德国营Neudorf厂加工套筒件的变薄拉伸是一种特殊的冷成形工艺,它为合理加工连轴件开辟了广阔前景,已获得极大的经济效益。这种变薄拉伸工艺属于冷体积成形,以精密钢管为原材料,可以加工全部套筒形零件,例如各种规格、品种的接轴套和轴套。加工轴     

渐开线螺旋花键冷滚轧工艺研究

随着汽车和摩托车工业的发展，对花键类零件的需要迅速增加，传统的机械加工工艺已不能适应这一发展，急需研制开发出适合花键类零件加工的高质高效的新型工艺。引文以ＣＹ－８０摩托车螺旋花键启动轴为研究对象，采用自由分度式冷滚轧的方法，对开线螺旋花键的冷滚轧工艺者了系统而全面地研究，并获得了成功。同传统工艺相比，冷滚轧的渐开线花键精度高、质量好、成本低、生产效率大大提高。所以，该工艺研制成功后，立刻替代了传统     

管坯模锻成形轮毂轴管技术的研究

根据汽车轮毂轴管零件的形状尺寸特点,分析了采用管坯模锻成形工艺的可行性,并制定了成形工步图.对各工步的工艺参数进行了计算,计算结果表明采用管坯成形轮毂轴管方案可行.制定了两种终锻成形方案,通过分析顺序成形锻件的头部形状为优选方案,但是缺点是模具结构复杂,或者设备投资大.最后对采用管坯成形和实心毛坯成形两种方案做了对比,结果表明,采用管坯成形锻件时由于不需要挤压内孔,大大地降低了成形力,在一定程度上改善模具的受力状况,提高模具的使用寿命.管坯成形汽车轮毂方案对实际生产有一定的指导意义,在一定程度上会提高其经济效益.     

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.