计算机模拟辅助优化变速器螺旋伞齿轮精锻成形工艺

针对螺旋伞齿在精锻时齿形成形质量差、成形载荷过大等缺陷,以某汽车变速器螺旋伞齿轮为研究对象,对其进行成形工艺分析,并采用数值模拟的方法,以螺旋伞齿精锻时的最大成形载荷值、最大等效应力、最大等效应变为研究目标,分析了成形工艺参数对齿轮成形质量的影响,得到了最优的成形工艺参数:坯料初始温度选择为1 000℃、摩擦系数为0.3、摩擦压力机的成形速度选择为200 mm/s。最后通过工艺试验结果表明,试验结果与模拟结果相一致,优化后的螺旋伞齿齿形饱满,满足汽车变速器螺旋伞齿的使用要求。     

螺旋锥齿轮温成形工艺参数的优化设计

齿轮成形载荷过大和齿形充满不均匀是目前螺旋锥齿轮近净成形技术的主要问题。本文运用正交试验法,通过刚塑性有限元法对闭式模锻螺旋锥齿轮温成形过程进行了模拟。研究了成形速度、毛坯温度、摩擦系数以及模具分流腔宽度四个参数对成形载荷和有效成形距离的影响。以成形载荷和有效成形距离为指标,优化出工艺参数并进行了验证。以优化工艺参数进行了锻造试验。结果表明,使用优化的工艺参数能有效地减少成形载荷以及有效成形距离。使用螺旋温优化工艺参数成形锥齿轮的结果与试验结果一致性较好。     

某VCR发动机齿板热锻成形参数研究

对某VCR (Variable Compression Ratio,可变压缩比)发动机齿板热锻成形进行参数影响和优化研究,可为锻件质量控制提供理论依据。基于DEFORM-3D,建立了该过程的有限元仿真模型,研究了坯料始锻温度和上模下压速度等参数对金属填充模腔情况、成形载荷、终锻件温度和等效塑性应力分布等的影响。结果表明:在研究的参数范围内,金属填充模腔完整,无折叠缺陷;当坯料始锻温度升高或上模下压速度加快时,各工步所需载荷和终锻件的最大等效塑性应力均减小,终锻件温度升高。最终获得了较优参数,即坯料始锻温度为1050℃、下压速度为50 mm·s~(-1)时,终锻件温度分布合理、填充饱满、无折叠和表面过度氧化缺陷,且锻件应力和成形载荷小,并对较优参数进行了实验验证。     

从动螺旋锥齿轮双锥辊辗压成形工艺参数优化

针对双锥辊辗压螺旋锥齿轮成形过程中型腔下模受力过大以及齿形充填高度不够的问题,首先,运用DEFORM-3D有限元软件对从动螺旋锥齿轮齿坯双锥辊辗压过程进行了模拟分析,研究了摩擦系数、辗压温度、凹模型腔进给速度对凹模型腔等效应力和Z方向成形齿高的影响;其次,采用正交试验设计方法,以凹模型腔等效应力和Z方向成形齿高为优化指标,得到了最佳工艺参数,并进行了数值验证;最后,通过数值计算分析以及与文献中研究结果进行比较分析,证明了从动螺旋锥齿轮双锥辊辗压成形工艺的可行性。结果表明:当摩擦系数为0.2、辗压温度为900℃、凹模型腔进给速度为2 mm·s~(-1)时,模具型腔受力最小,齿形的充填饱满,高度达到最高。     

汽车发动机支架零件坯料优化设计

以汽车发动机支架为研究对象,为减少其加工时的坯料,结合数值模拟结果,提出了3种方案,确定了减少原坯料体积的15%为最优方案,并在此基础上进行正交试验,对优化后的坯料进行工艺参数的优化。结果表明,坯料的大小对折叠的产生有着重要的影响。综合折叠角大小、模具载荷及应力分布等因素,确定了最佳工艺参数。当压力机工作速度为85 mm·s~(-1)、坯料半径为90 mm、坯料初始温度为420℃、摩擦系数为0.3时,锻件成形质量较好。通过实际生产验证获得了符合要求的产品。     

汽车蓄能器壳体件挤压成形工艺研究

基于Deform-3D软件平台,通过数值模拟对汽车蓄能器壳体件的挤压成形过程进行工艺优化。建立正交试验方案,分析各个因素对挤压成形过程的影响,以成形载荷作为评判标准确定了最佳工艺参数组合。通过实验最终得到了最佳成形工艺参数为:温挤压模具温度230℃,温挤压坯料温度1000℃,温挤压摩擦系数0.15,温挤压凸模速度12mm.s-1,冷挤压凸模速度8mm.s-1,冷挤压摩擦系数0.08。按照该工艺参数进行实际零件的挤压生产,最终得到了符合要求的成形零件。     

基于正交试验的铝合金筋板类锻件成形工艺参数多目标优化

为了获得更好的铝合金筋板类锻件锻造成形工艺参数,采用正交试验和有限元模拟技术对锻造成形工艺参数进行了多目标优化。以铝合金筋板类锻件成形载荷和金属流动速度作为评价指标,分析成形速率、坯料温度、摩擦系数、飞边槽桥部宽度和高度对锻件质量的影响。并用极差分析法分别得到成形载荷和流动速度的最优工艺参数。最后利用多目标综合平衡法,获得成形载荷和金属流动速度的工艺参数组合,并对最优工艺参数进行了验证。     

基于Deform的剥皮齿热锻过程仿真及工艺参数优化

剥皮齿作为木材剥皮机的刀具,其在高强度作业下,要求硬度高、耐腐蚀性强。提出了采用锻造成形方式加工剥皮齿,并基于Deform-3D模拟软件分析了剥皮齿热锻工艺参数对锻造成形质量的影响,揭露了剥皮齿热锻过程的成形规律,验证了设备选型、锻造方案及模具设计的合理性。通过正交试验对热锻过程中的工艺参数设置进行优化,最终制定了坯料温度为1180℃、预锻上下模间距为3.0 mm、终锻上下模间距为3.3 mm、上模运动速度为500 mm·s~(-1)、摩擦因数为0.25的优化工艺参数组合。采用优化后的工艺参数组合方案,上模载荷相对于优化前降低了4.48%,提高了锻件的内部质量与模具的使用寿命。     

工艺参数对管端加厚成形影响的数值模拟研究

管端加厚工艺过程中，工艺参数的设定对产品最终成形质量具有显著影响。为了深入探究不同工艺参数对管端加厚成形过程的影响，利用三维建模技术结合Deform-3D软件，建立了油管管端加厚成形过程的有限元数值模拟模型，分析了坯料加热温度、冲头与坯料间摩擦系数、冲头进给速度以及坯料加热长度等四种工艺参数的变化对管端加厚最终成形质量和设备载荷的影响，并探究了其变化规律。结果表明，提高加热温度，降低摩擦系数，选取适中的冲头进给速度和管坯加热长度可有效提高加厚成形的最终产品质量，延长模具寿命，降低设备载荷。     

基于灰色系统理论的同步器齿环的成形工艺研究

针对铜质同步器齿环热精锻成形的材料利用率低、成形载荷大的问题,基于FORGE软件对齿环热精锻成形工艺进行研究。基于金属塑性成形理论,分析齿环成形过程中金属的流动规律。以坯料始锻温度、摩擦因数、坯料内径和坯料高度为变量,设计了4因素4水平正交试验,获得最大成形载荷、内外飞边径向尺寸数据。结合灰色系统理论对齿环热精锻成形工艺参数进行优化,获得最优工艺参数组合并进行工艺试验。试生产结果表明,齿环充填饱满、无折叠和开裂缺陷,材料利用率提高至63.73%,验证了优化工艺参数组合和灰色系统理论优化方法的可行性。     

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.     

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.