电机转子鼠笼铸件铸造过程数值模拟

依据实际生产中压铸工艺参数,采用Procast软件对电机转子鼠笼的充型过程和凝固过程进行数值模拟。根据对充型过程分析结果,研究充型过程中铝液速度变化以及型腔内的气压分布。通过对凝固过程分析,研究铸件凝固特性和铝液温度变化规律,并预测可能出现的缺陷。结果表明,在铝液温度为710℃,模具预热温度为200℃,浇注速度为2 m/s时,缩松、缩孔主要集中在转子端环部位。最后提出结构优化方案并进行模拟,改善缩松、缩孔分布情况,并运用至实际生产进行验证。     

AlSi7Mg连杆半固态挤压铸造成形数值模拟

通过Magmasoft软件的Ostaward-de Waele粘度模型,对AlSi7Mg连杆的半固态挤压铸造成形过程进行了模拟,并对凝固过程进行了分析.通过数值模拟,获得了浇注温度、模具预热温度、冲头速度对连杆成形质量的影响规律.结果表明,优化的AlSi7Mg连杆半固态挤压铸造成形工艺参数为:浇注温度为576～585℃、模具温度为200～250℃、冲头速度为0.1～0.5m·s-1.在该工艺参数下进行半固态挤压铸造成形,金属浆料流动平稳,凝固时间较短,AlSi7Mg连杆铸件缺陷少.     

A356合金连杆半固态挤压铸造工艺参数的优化

基于ProCast2008软件平台,用其自带的非牛顿流体模型Power Law Cut-Off (PLCO)来建立流动模型,对A356合金连杆半固态挤压铸造铸造的充型和凝固过程进行了数值模拟.研究了浇注温度、冲头速度、模具预热温度等主要工艺参数对连杆半固态挤压铸造铸件成形品质的影响规律,获得了连杆半固态挤压铸造铸造的合理工艺参数:浇注温度为576～583℃、模具温度为200～250℃、冲头速度为0.1-0.5 m,s-1.在该工艺参数下进行成形,金属浆料填充平稳,凝固时间较短,挤压铸件缺陷少.     

铝合金支架间接挤压铸造的工艺设计

初选4组不同的浇注温度和压射速度,对铝合金支架的间接挤压铸造充型过程进行了数值模拟,以此选定了合理的浇注温度和压射速度,然后对选定的工艺参数进行了间接挤压铸造充型和凝固过程的数值模拟,确定了合理的模具结构,最后制作了模具并试制了铸件.     

A356合金半固态挤压铸造数值模拟及模具优化

采用Anycasting软件对A356合金铸件半固态挤压铸造过程中充型和凝固过程进行数值模拟。研究了压射速度、浇注温度对半固态A356铝合金挤压铸造过程的影响,对工艺参数进行了优化,并对压铸模具进行了改进。结果表明,模具预热温度为200℃,浇注温度为600℃,压射速度为0.5m/s,内浇口厚度为5mm时,能够获得质量理想的铸件。     

改进压铸模设计提高转子铸铝质量

<正> 转子铸铝是电机制造的关键工序之一。铸铝质量的优劣,效率的高低将直接影响电机的性能和生产成本。 对于小型电机的鼠笼转子,特别适合用压力铸造,这是因为: 1.效率高适合大批量生产。 2.小型鼠笼转子的端环、笼条以及风叶的厚度较小,其厚度差别也不大,适合于压铸。 3.对于较小的转子,能够一模多件,大大提高了劳动生产率。 4.只要模具设计合理,则其制造、维修和更换都很方便。 5.一般比用其他方法更能够保证产品质     

曲轴箱壳多向挤压铸造温度参数优化与试验

利用有限元法对摩托车曲轴箱壳多向挤压铸造进行了数值模拟,分析了浇注温度、上模温度、下模具温度与零件缩松、致密度的关系,得到了优化的温度参数,并通过试验加以验证.研究表明:对局部壁厚差大、结构复杂的零件,多向挤压铸造得到的铸件质量优于普通挤压铸造,浇注温度为680℃,上、下模具温度为200℃时,摩托车曲轴箱壳缩松区域由10％降到7％.浇注温度对零件缩松和致密度的影响最为显著,上模温度比下模温度略高,有利于提高铸件质量.     

基于ProCast铝合金电机壳挤压铸造工艺设计

针对使用常规铸造工艺制造的新能源汽车电机壳出现缩松缩孔、气密性合格率低的问题,应用数值模拟技术对电机壳的挤压铸造工艺进行研究。通过对铸造充型、凝固过程进行模拟仿真,验证工艺设计的合理性,并结合单一变量法研究浇注温度、模具温度、比压等工艺参数对缩松缩孔的影响。最终确定最佳工艺参数为浇注温度680℃,模具温度280℃,比压110 MPa、压射速度0.1 m/s、保压30 s。在此参数下结合局部加压装置可以消除铸件的缩松缩孔,得到的铸件性能优良,气密性合格率达到88%。     

半固态镁合金挤压铸造工艺模拟分析及优化

采用ProCAST软件,对半固态镁合金电机部件的挤压铸造过程进行模拟。分析了半固态挤压铸造的浇注速度(注射速度)、浇注温度和模具冷却条件等参数对半固态挤压铸造充型及凝固的影响。结果表明,浇注速度、浇注温度和冷却条件对半固态挤压铸造的充填和凝固有显著影响。通过优化,采用适当的浇注速度、浇注温度和冷却条件,可保证挤压铸造充型过程的平稳充填,减少卷气和缩松等缺陷。     

利用ProCAST探索浇注温度对转子质量的影响

运用铸造过程数值模拟软件ProCAST,对转子铸件进行了浇注温度的模拟仿真分析,以研究不同浇注温度对QT400-15转子铸件缺陷的影响。结果显示:温度过高虽然可以提高流动性,但是同时会增加液体在凝固过程中的收缩量,导致缩孔缩松缺陷;而温度过低,又会导致铸件力学性能达不到要求。根据试验情况,浇注温度宜选在1 340~1 360℃。     

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.