单齿履带板锻造工艺研究和模具开发

大节距260 mm单齿履带板属于异形薄板类锻件,是履带式工程机械车辆行走系统的关键部位。经过对产品特点的分析,提出了大节距单齿履带板锻造过程的工艺开发,在试验后确定了模锻工艺方案。根据产品锻造过程中受力情况和金属流动规律,设计开发出"预锻制坯"的半开半闭式模具和"终锻成形"的闭式模具,完成对单齿履带板的锻造生产。检测结果表明,锻件成形效果好,尺寸达到图纸要求,质量稳定,能够满足生产使用要求。     

厚壁筒接管的成形工艺优化

长期以来,核电等设备厚壁筒体上的接管均采用焊接方式连接,但焊接管一直存在强度方面的隐患。以锻造接管取代焊接管,将大大提高核电筒体的强度,因此,有必要对锻造接管成形工艺进行深入研究。课题利用ANSYS软件,对锻造接管成形过程进行了数值模拟分析,确定了影响锻造接管成形的主要工艺因素。利用一种具有新监控技术的约束变尺度方法,成功地对核电筒体接管锻造成形工艺参数进行了优化计算,确定了毛坯和模具的尺寸,最后成功地用铅管进行了工艺试验。     

大型盘类件成形工艺及模具设计

分析了大型盘类件——驱动盘的结构特点及现有设备的情况,经过分析、计算、试制,采用径向分料方法分2步成形,扩大了自由锻设备的加工范围。详细论述了驱动盘的锻造工艺方案、模具设计过程、模具结构及工作过程。该工艺及模具已在实际生产过程中得到验证,是一种具有投资少、生产周期短、锻件质量好、不需要大型模锻设备的先进工艺。     

薄壁曲面零件的锻造成形工艺

某产品上用的一重要零件为薄壁曲面类零件,实际生产中主要采用机械加工制作,工序多,时间长,并浪费原材料.本文采用锻造成形工艺,锻模设计为曲面分模面模具结构,实现了薄壁曲面零件的锻造成形.零件成形后,无需再进行后续机械加工,产品的尺寸和形状均可直接达到使用要求.经过工艺试验和小批量的试生产考核,其尺寸和形状均能满足图纸技术要求,并且产品尺寸和形状的一致性好.与机械加工工艺相比,锻造成形工艺大幅度提高了产品生产效率和材料利用率,极大降低了生产成本.     

摩托车连杆锻造过程的数值模拟

利用刚塑性有限元仿真软件DEFORM-3D,对摩托车连杆锻造成形整个过程进行了数值模拟,对应力、应变分布、模具载荷计算、材料流动速度、毛坯尺寸优化、模具圆角优化等作了深入研究,为模具及成形设备的设计和工艺优化及制坯工步提供了可靠依据。     

基于Deform软件的四通管道阀热锻过程模拟及模具优化设计

采用自由锻工艺成形四通管道阀阀体的材料利用率低下。本文采用精密模锻工艺生产四通管道阀体,并利用Deform软件模拟了金属坯料在锻造模具中的流动过程和成形规律,分析了不同尺寸参数的坯料和飞边槽对锻造质量的影响,确定了最佳的坯料参数和飞边槽参数。     

大尺寸钛合金蒙皮热成形工艺及模具设计

从大尺寸钛合金蒙皮零件的结构及热成形工艺特点出发,确定了主要成形工艺参数,完成了模具型面缩尺系数的计算及尺寸精度的选取;从模具的工作温度特殊性出发,进行了结构设计及热状态下的静力学分析。该模具投入使用安全可靠,生产的蒙皮零件满足设计要求,为类似零件的成形提供了参考。     

电子陶瓷热压注模尺寸计算

<正> 采用热压注成形法制造的各种电子陶瓷零件,除热压注模具不同外,其余所使用的设备、工具及各工序工艺要求等都是相同的。因此,热压注模具是生产电子陶瓷零件最为重要的工具。设计热压注模,一是确定模具结构,二是确定模腔尺寸;而模腔尺寸乃是决定产品尺寸是否合格及模具磨损寿命的主要因素。至今在工厂流行的计算热压注模     

悬垂线夹锻造模具的研究与应用

本文通过分析锻造模具研究现状和生产悬垂线夹锻造模具所用材料性能,提出精密模锻模具的有效设计。通过工艺实验,确定了其结构尺寸、锻造工艺流程、锻造温度以及热处理状态等因素对悬垂线夹体成形工艺与性能的影响。利用工艺实验进一步优化和改善了锻件的结构与尺寸,有效克服模锻过程中出现的夹层、充不满以及出模困难等技术难点。解决了模具性能偏低的问题,明确了脱模方式,对锻造与热处理的工艺参数与工艺流程进行了优化,最终得到具有良好外观与表面品质的产品。     

基于灰色关联分析的7050铝合金轮毂锻造工艺优化

为改善7050铝合金轮毂锻件的质量,对其锻造工艺进行研究。以模具温度、坯料温度、成形速度及摩擦系数为研究对象,以平均晶粒尺寸和平均再结晶百分数为优化目标,基于灰色关联分析将多目标优化转化为单目标优化,利用主成分分析确定平均晶粒尺寸和平均再结晶百分数对灰色关联度的影响权重,从而确定最优工艺参数;通过对试验数据的回归分析,建立灰色关联度与锻造工艺参数的二阶预测模型。结果表明,由δmax值可知,铝合金7050轮毂锻造过程最优工艺参数是模具温度为450℃、坯料温度为460℃、成形速度为8 mm·s-1、摩擦系数为0.1,并在实际生产中验证了该组工艺参数的合理性和所提方法的有效性。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.