大型复杂薄壁铝合金铸件调压成形精密铸造技术

西北工业大学周尧和院士等针对大型复杂薄壁部件的铸造生产难题而发明了一种大型复杂薄壁铝合金铸件调压成形精密铸造技术。采用该技术生产大型复杂薄壁铸件，能够在金属液平稳进入铸型型腔的同时保持优异的充型能力和补缩能力，在保证大型复杂薄壁铸件成形精度的同时获得优异的冶金质量，使铸件晶粒细化，致密度提升，铸件性能提高。     

大型铝合金汽车底盘一体化砂型铸造技术

针对大型铝合金汽车底盘铸件的结构特点，分析铸造工艺难点及要点，提出大型铝合金汽车底盘一体化砂型铸造技术，并进行合金熔体净化、合金晶粒组织细化、薄壁件完整充型、尺寸精度控制等方面的研究。研究结果表明，通过合金熔体净化、合金晶粒组织细化，可以获得本体各向同性、力学性能优异的大型铝合金汽车底盘铸件。通过一体化砂型铸造技术，获得充型完整、内部质量优良的大型铝合金汽车底盘铸件，达到设计要求。     

石膏型低压铸造工艺规程的研究与应用

基于低压铸造生产要求，对石膏型制备与烘干工艺、合金熔炼与浇注工艺进行研究，升液管预热有利于均匀喷涂涂料，升液管口平面上放置石棉垫板和过滤网片可提高服役寿命。旨在为薄壁叶片和大型复杂薄壁铸造铝合金铸件的生产提供科学依据。     

大型薄壁复杂铝件铸造技术的现状与发展

随着航天、国防、汽车等工业的不断发展，对铸件的要求向小余量、薄壁、高精度、高性能方向发展：介绍了大型薄壁铸件的特征，叙述铝合金复杂薄壁铸件的发展特点，提出复杂薄壁铸件对先进的精密成形技术及铸造工艺的要求.     

离心力场下铸造充型行为数值模拟

建立了离心力场下铸造充型流动的数学模型,采用VC++语言自行编制了离心力场铸造充型及凝固传热的计算机模拟软件。通过模拟旋转圆柱容器中的液体从重力静止水平自由表面状态过渡到离心抛物面自由表面的动态变化过程,并与理论解析曲线对比,以及钛合金薄壁件离心浇注充型状态与试验结果的对比,检验了所建立的理论模型及计算程序的正确性。通过对钛合金薄壁铸件在重力场与离心力场浇注工艺条件下合金熔体充型行为数值模拟结果的对比表明,在一定转速条件下,金属液的离心浇注比重力浇注具有强得多的薄壁充型能力。     

铝合金车门内板挤压铸造工艺优化的有限元模拟

采用Flow-3D软件建立了ADC12铝合金车门内板挤压铸造过程的有限元模型,探讨了模具温度、浇注温度和压机下压速度对熔体充型状态的影响,对挤压铸造工艺进行了优化,并进行了试验验证。结果表明:浇注温度高于953K,充型结束时低于固相线温度的区域逐渐减小;模具温度会影响铸件充型边缘区域的温度;高速下压会产生过多的气孔、氧化渣夹杂,不利于铸件顺序凝固;当浇注温度不低于953K,模具温度不低于583K,压机下压速度为24mm·s-1时,可以成功制备结构完整的铝合金车门内板铸件;试验结果证明了模拟结果的正确性。     

大型薄壁高强度铝合金铸件成形研究

为节约原材料，降低生产成本，以高强度铝合金铸件代替铝合金棒制造大型薄壁铝合金件，应用金属型铸造和砂型铸造原理，对大型、薄壁回旋体高强度铝合金铸件的铸造工艺进行了试验研究。结果表明，采用金属型和砂型相结合的铸造工艺，能满足其铸件质量要求，这是一种简单、经济、实用的铸造新工艺方法。     

充型压力对石膏型反重力铸造ZM5镁合金组织和拉伸性能的影响

将石膏型熔模铸造和反重力铸造工艺相结合,在不同充型压力下制备ZM5镁合金,研究了充型压力对镁合金石膏型薄壁件成形能力及合金铸态组织和拉伸性能的影响,得到了最佳的铸造工艺参数。结果表明:随着充型压力增大,铸态镁合金的组织明显细化;当充型压力为40kPa时,铸件的成形能力最好,镁合金的拉伸性能最佳,抗拉强度为(192±5)MPa,伸长率为(1.5±0.2)%;330~350℃的铸型预热温度、730~750℃的浇注温度、35~40kPa的充型压力能够满足镁合金薄壁件浇注的需要。     

低压铸造铝合金筒体的质量控制措施研究

低压铸造有着生产效率高、经济性能好的优势,在铝合金铸件的生产中有着广泛的应用。同时,低压铸造平稳可靠、充型能力强,随着技术的成熟,其在优质铝合金铸件、薄壁铸件中的应用越来越广泛。本文就低压铸造铝合金筒体的质量控制措施展开分析。     

新型铝硅基铸造壳体凝固成形研究

新型铝合金材料用于薄壁壳体铸件制备,通过向ZL101A合金中增添微量Ni元素,基于ProCAST铸造仿真软件设计液压泵壳体低压铸造工艺,数值模拟铸件不同部位固相出现时间,并预测铸件凝固过程中缩孔缩松现象。实际生产铝合金薄壁壳体铸件,并对壳体棒料进行高温压缩实验,利用结构变形机理以及微观组织特点分析铸件凝固成形机理。分析合理的浇注温度以及热处理工艺,能够对壳体铸件缩孔缩松现象进行有效控制,保证改进铝硅合金薄壁壳体铸件质量。     

Influence of gas flowrate on filling ability and internal quality of A356 aluminum alloy castings fabricated using the expendable pattern shell casting with vacuum and low pressure

In this study, a new casing process named expendable pattern shell casting process with vacuum and low pressure (EPSC-VL) was introduced to produce complicated and thin-walled aluminum alloy castings. The gas flowrate is one of the most important process parameters for manufacturing castings during the EPSC-VL process. In the present work, the influence of gas flowrate on the filling ability and internal quality of A356 aluminum alloy castings fabricated by the EPSC-VL process were investigated. Moreover, the filling ability, internal quality, as well as mechanical properties of A356 aluminum alloy castings obtained by EPSC-VL and lost foam casting (LFC) processes were also compared. The results obtained suggested that the filling length increased with the increase of gas flowrate, and the filling length of the thick section was larger than that of the thin section under the same gas flowrate when the gas flowrate was less than 19 m³/h. Furthermore, the porosity of castings decreased with increasing gas flowrate, and the microstructure of castings became denser, and the internal quality of castings was obviously improved. The comparison experiments showed that the EPSC-VL process had superior filling ability, internal quality, and mechanical properties compared with the LFC process, and the surface quality of castings obtained by EPSC-VL process was also better than that of the LFC process. The casting practice of complicated and thin-walled A356 aluminum alloy intake manifold part also suggested that the EPSC-VL process had an obvious advantage for the fabrication of complicated and thin-walled aluminum alloy castings compared with the LFC process.     

A new shell casting process based on expendable pattern with vacuum and low-pressure casting for aluminum and magnesium alloys

A new shell casting process, with the adoption of the foam pattern of lost foam casting (LFC) as prototype and the combination of the thin shell fabrication technology of investment casting and vacuum and low-pressure casting process, was proposed for manufacturing complicated and thin-walled aluminum and magnesium alloy precision castings. Loose-sand uniting vacuum was used in the new process to further reinforce the thin shell, and the new process proves to be a process with simple process, low cost, and high thin shell strength. Because the molten metal filling and solidification are completed under air pressure and vacuum level, the filling capability and feeding capacity of the molten metal are greatly improved, and the castings become denser. This paper mainly investigated the fabrication technology of thin shell based on foam pattern prototype, the removing foam and roasting shell process and vacuum and low-pressure casting process. The few-layer compound thin shell of silica sol–sodium silicate was adopted for the new process. Removing foam pattern was carried out at 250°C for 30 min, and the shell was roasted at 800°C for 1 h. Combined with the vacuum and low-pressure casting process, this new shell casting process has successfully produced thin wall and complex aluminum and magnesium alloy parts with high quality. In addition, comparisons in terms of filling ability, microstructure, mechanical properties, porosity, and surface roughness among this new shell casting, gravity casting, and LFC were also made to show the characterization of this new shell casting process.     

镁合金真空低压消失模铸造新技术

介绍了一种新的铸造技术--真空低压消失模铸造的工作原理.建立了其在充型过程中的物理模型与数学模型,分析了其铸造工艺的特点及影响因素,以及在铸造高精度、复杂镁合金铸件方面的优势.作为压力铸造、低压铸造的补充,真空低压消失模铸造新技术在铸造高质量和高精度的镁合金铸件中具有广泛的应用前景,另外还可用于铸造高精度、复杂的铝合金铸件.展示了用该新技术铸造成形的复杂的电机壳体、排气管等镁合金铸件.     

铝硅基精铸材料薄壁壳体成型多尺度分析

针对铝合金薄壁壳体铸造成型高质量要求,通过向ZL101A铝合金中增添Al-10Sr变质剂以及微量Ni元素,制备铝硅基精铸材料坯件,借助加热设备与SCC-44500电子万能试验机对铝硅基精铸材料进行高温压缩试验,得到不同应变率与不同温度下材料的应力-应变曲线,发现铝硅基精铸材料在各应变率及温度下的屈服强度相对ZL101A铝合金均提高。以铝硅基精铸材料进行液压泵薄壁壳体铸造工艺设计分析,基于ProCAST铸造模拟软件,采用低压铸造工艺方案对铝合金薄壁壳体低压铸造过程进行多尺度模拟,分析预测得到了温度场和流动场对铸件充型和凝固过程中缩孔缩松形成的影响,并对壳体铸件的显微组织特征进行了分析,观察得到内部二次枝晶臂间距和共晶层片间距分布状态,综合分析宏微观结果可知,适合的铸造工艺可以制备出完整高性能的铝硅基合金薄壁壳体铸件。     

低压铸造铝合金车轮充型过程数值模拟的研究

利用数值模拟技术,对低压铸造铝合金车轮的流动、充型过程进行了分析。应用表明,流动场数值模拟技术可以跟踪液态金属的充型形貌,分析各部位的压力分布,为优化铸造工艺、改进模具设计提供了有效的手段。     

铝合金铸造中影响薄壁流动性的因素分析

铝合金铸造工艺在很多领域得到较好应用,为航天制造、汽车制造等提供了新的发展方向。铝合金铸造中最重要的问题就是解决薄壁流动性的影响因素问题,将从铝合金铸造当中对薄壁产生影响的因素以及填充条件对薄壁流动性产生影响的因素等方面着手,对铝合金铸造中影响薄壁流动性的因素进行了分析。     

Determining casting defects in near-net shape casting aluminum parts by computed tomography

Three types of near-net shape casting aluminum parts were investigated by computed tomography to determine casting defects and evaluate quality. The first, second, and third parts were produced by low-pressure die casting (Al-12Si-0.8Cu-0.5Fe-0.9Mg-0.7Ni-0.2Zn alloy), die casting (A356, Al-7Si-0.3Mg), and semi-solid casting (A356, Al-7Si-0.3Mg), respectively. Unlike die casting (second part), low-pressure die casting (first part) significantly reduced the formation of casting defects (i.e., porosity) due to its smooth filling and solidification under pressure. No significant casting defect was observed in the third part, and this absence of defects indicates that semi-solid casting could produce high-quality near-net shape casting aluminum parts. Moreover, casting defects were mostly distributed along the eutectic grain boundaries. This finding reveals that refinement of eutectic grains is necessary to optimize the distribution of casting defects and reduce their size. This investigation demonstrated that computed tomography is an efficient method to determine casting defects in near-net shape casting aluminum parts.     

国际标准GCuAl10Fe5Ni5合金熔模铸件工艺实践

分析了国际标准GCuAl10Fe5Ni5合金铸件的结构特点及工艺性能,结合熔模精密铸造浇注系统的设计原则,进行了熔模铸件浇注系统的工艺设计,给出了含有蛇形浇道底注式的工艺设计方案。通过控制制壳及合金熔炼工艺过程,对工艺方案进行了工艺实践,并对其间出现的铸件缺陷进行了原因分析,提出了改进措施并加以实施,使铸造工艺方案得到了进一步完善,所生产铸件合格率大幅提高。     

快速成型技术在熔模精密铸造中的应用

快速成型技术是具有高柔性的先进制造技术,无需任何专用工具,由零件的CAD模型直接完成零件或零件原型的成型制造。将快速成型技术与铸造技术结合起来,采用快速成型技术制造铸型或铸模,可极大提高铸造的柔性和生产效率,满足新品试制和小批量生产的需求,这也是快速成型技术的一个主要发展方向。本文通过几种快速成型模在熔模精密铸造中的实际应用和试验得出,采用SLA法制作的蜂窝结构快速成型模在尺寸波动方面满足精铸需要,并能实现铸件的快速制造。