12500 kN冷锻压力机机身结构的有限元分析

为了研究侧向力对压力机机身强度和刚度的影响,以北京机电研究所有限公司自主研发设计的CWEP12500 kN冷锻压力机为研究对象,针对其在工作过程中的受力特点,提出3种机身受力模型,运用ANSYS Workbench软件进行静力学分析,得到了3种加载方式下机身的应力和变形。结果表明,3种加载方式得到的机身应力均在60 MPa左右,满足要求。当机身承受由滑块的锻造力分解出的水平侧向分力时,立柱产生0.32 mm的变形量,不符合0.2 mm的经验许用值。立柱产生过大变形量会对滑块导向产生不利影响,加剧导轨和滑块的磨损,影响压力机成形精度。因此,在今后的设计计算中,应当将机身受到的侧向力作为影响压力机刚度的因素之一,并且注意立柱尺寸和结构的优化,以增加其刚度。     

5000kN机械压力机机身有限元分析

运用SolidWorks软件对某5000 kN机械压力机机身进行实体建模,并运用ANSYS软件对其进行结构分析和模态分析;通过模态分析获得结构的固有频率;通过结构分析获得应力和变形的分布情况,在此基础上分析压力机机身设计是否合理.针对组合框架式压力机的预紧问题,分别采用了直接加载法和热-结构耦合法两种预紧方法,并对两种预紧方法计算结果进行了比较.     

螺旋压力机整体机身工作状态仿真及结构优化

利用CAE软件MSC、MARC对公称力为4000kN螺旋压力机的整体铸钢机身进行了工作状态仿真，得出其应力及变形结果，并以此为基础了结构优化改进，研究了机身结构对机身强度和风度的影响，其研究结果对重型机构机身优化设计有着重要意义。     

1600kN开式压力机机身结构分析与改进

1600k N开式压力机在使用过程中会出现角变形,从而影响模具寿命及工件精度。为此,在原机身结构上提出新的改进方案,以减小开式机身角变形,提高工件精度和模具使用寿命。采用Solid Works建模,结合有限元分析软件ANSYS,分析并比较了改进前后两种结构的变形、应力与应变,为减小开式压力机角变形的影响提供依据。     

基于有限元计算的冷锻压力机组合机身的结构优化

以连杆式冷锻压力机的闭式组合机身为研究对象,将机身三维模型导入Workbench中建立有限元分析模型,进行静力学分析和模态计算,得到机身应力整体在160 MPa以下,机身挠度为0. 36 mm,一阶频率为15. 886 Hz,均满足使用要求。立柱Z向变形为0. 32 mm,超过许用值0. 2 mm,因此机身有优化的余量和必要。采用多目标优化的方法,以静力学分析为基础,定义机身不同板厚为设计变量,设置机身受到的应力、立柱Z向变形为约束条件,以机身重量为目标函数。对比3组不同计算结果得到的优化方案,选择方案1:机身重量由73828 kg变为66706 kg,机身重量减少9. 6%,实现了机身的轻量化。对优化后的机身进行刚度计算和模态分析,得到机身挠度为0. 35 mm,立柱Z向变形量为0. 18 mm,一阶频率为15. 688 Hz,可以满足实际使用要求。因此在压力机设计中,可以考虑减薄板厚,以实现在满足使用要求的前提下达到机身减重、降低制造成本的可能。     

基于Workbench的重型电动数控螺旋压力机机身轻量化设计

针对当前压力机机身笨重与材料浪费的问题,以EP-12500重型电动数控螺旋压力机机身为研究对象,探索压力机机身结构的轻量化设计方法。首先,基于Workbench对压力机机身进行有限元分析,得到机身应力值远小于材料屈服强度的非承载区域;然后,采用拓扑优化模块对机身非承载区域进行拓扑优化;最后,以质量最小化为目标,确定机身结构材料去除区域的具体位置,实现对机身结构的轻量化设计。优化结果表明：优化后压力机机身的体积与质量均减小了9.65%,实现了机身轻量化,减少了制造成本;机身预紧工况下最大变形量增加了0.17 mm,打击工况下最大变形量增加不足0.01 mm,与原机身变形基本一致;机身预紧工况下垂直刚度为8.21 MN·mm^-1,打击工况下垂直刚度为13.08 MN·mm^-1,均满足使用要求;机身预紧工况下最大等效应力降低了2.51%,打击工况下最大等效应力降低了18.3%,降低了底座承受的冲击力,提高了底座的使用寿命。     

开式数控冲模回转头压力机机身的振动

从分析曲柄压力机机身所受的干扰力入手，讨论了曲柄压力机在最坏条件下机身的振动，从而获得了求其机身最大动态垂直变形、最大动态角变形和机身危险截面动应力的途径。并以数控冲模回转头压力机为例，就如何计算机身的固有频率进行了探讨，为曲柄压力机机身的动态性能设计并提高其行程次数提供了理论依据。     

J92—10型数控回转头压力机机身结构的优化设计

对新开发的J92－10型开发数控回转头压力机机身受力进行有限元分析与计算,研究在公称压力下,机身不同结构形式及钢板厚度对变形的影响,以及机身的变形和应力分布,依此对机身结构进行优化设计。     

开式数控冲模回转头压力机机身的振动

从分析曲柄压力机机身所受的干扰力入手，讨论了曲柄机在最坏条件下机身的振动，从而获得了求其机身最大动态垂直变形，最大动态角变形和机身危险截面动应力的途径。并以数控冲模回转头压力机为例，就如何计算机身的固有频率进行了探讨，为曲柄压力机机身的动态性能设计并提高其行程次数提供了理论依据。     

组合式大型压力机横梁强度刚度分析

通过三维建模软件建立1600t压力机机身分析模型,并导入ANSYS有限元计算软件进行仿真分析对比.通过将计算步骤分解,对组合式压力机进行分析,为组合式大型压力机的分析提供一种新的方式和思路.解决了大型组合式压力机中零部件的强度和刚度分析优化问题.解决了带拉紧螺杆预紧的压力机,真实变形的分析计算,并找出零部件具体的薄弱点.最后通过压力机机身的变形确定曲轴与机身的间隙范围,以及立柱上导轨与滑块的间隙问题.     

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.     

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。     

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).     

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.     

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.