ZL101A铝合金机构箱成型工艺及模具设计

针对目前ZL101A铝合金机构箱零件毛坯生产采用常规砂型铸造存在铸件致密度低、表面粗糙度较高和生产效率低的问题,采用金属模铸造工艺并设计了一套金属型模具,主要内容有铸件图设计、机构箱熔铸工艺分析及金属型模具设计.结果表明,由于金属型冷却速度较快和铸造条件比较稳定,所得机构箱铸件组织较致密,并具有较好的尺寸精度和表面粗糙度,生产效率也有很大提高.     

Effect of reacted compounds in Al2O3+Ti investment mold on alpha-case formation for Ti casting

This paper proposes a newly developed alpha-case controlled mold material for Ti castings. An Al₂O₃ mold containing alpha-case reaction compounds, titanium oxide (TiO₂, Ti₂O and Ti₆O) and titanium silicide (Ti₅Si₃) was manufactured via a reaction between Al₂O₃ and Ti powder under different firing conditions in air and a vacuum. In comparison with the Al₂O₃ and Al₂O₃+Ti mold fired in a vacuum, the micro-Vickers hardness and nano indentation profiles of Al₂O₃+Ti indicated that the alpha-case thickness was significantly reduced from 350 μm to ～45 μm. The alpha-case formation in the Al₂O₃+Ti mold was reduced due to the presence of TiO₂, which formed the TiO intermediate phase that acted as a diffusion barrier. In addition, Ti₅Si₃ was effective in minimizing Si contamination at the casting surface due to the reaction between Ti and the colloidal SiO₂ binder. Therefore, alpha-case reaction compounds, such as TiO₂ and Ti₅Si₃ in Al₂O₃, can effectively reduce alpha-case formation at the casting surface.     

Investigation of interface reaction between TiAl alloys and mold materials

This paper describes the investment casting of TiAl alloys. The effects of mold mateiral and mold preheating temperature for the investment casting of TiAl on metal-mold interfacial reaction were investigated by means of optical micrography, hardness profiles and an electron probe microanalyzer. The mold materials examined were colloidal silica bonded ZrO₂, ZrSiO₄, Al₂O₃ and CaO stabilized ZrO₂. When compared with conventional titanium alloy, the high aluminum concentration of TiAl alloys helps to lower their reactivity in the molten state. The Al₂O₃ mold is a promising mold material for the investment casting of TiAl in terms of the thermal stability, formability and cost. Special attention need to be paid to thermal stability and mold preheating when developing the investment casting of TiAl alloys.     

大型复杂圆台型钛合金铸件的铸造工艺研究

针对某大型复杂圆台型钛合金铸件结构特点,设计了两种铸造工艺,并结合模拟仿真对铸造工艺进行优化,其中直立底注式铸造工艺更优。采用石墨型铸造并进行了生产验证,得到品质满足GJB2896A-2007中I类高品质铸件要求。     

磷酸盐粘结剂用于陶瓷型艺术铸造

介绍了一种以磷酸盐为粘结剂制作陶瓷型的工艺方法。该陶瓷型用于制作金属工艺品，尺寸精度和表面粗糙度均达到技术要求。与传统的熔模铸造以及硅酸乙酯为粘结剂制作的陶瓷型相比，具有制作工艺简单、适应性强、成本较低的特点。该陶瓷型还可用于某些熔模铸件的生产。     

钛合金离心精密铸造充型过程计算机模拟

建立了离心力场下铸造充型流动的数学模型 ,在自行研制的三维铸件充型 /凝固模拟软件 (CASM 3DforWin dows)基础上 ,研制开发了相应的离心力场铸造充型的计算机模拟软件。对钛合金薄壁铸件在重力场下及不同离心精密铸造工艺条件下的充型过程进行了实例模拟计算。计算结果表明 :在离心力场下金属液的薄壁充型能力比重力浇注强得多 ,而“拐头反充”式离心浇注方式是一种合理的离心力场下的铸造工艺方案     

Computer simulation for centrifugal mold filling of precision titanium castings

Computer simulation codes were developed based on a proposed mathematical model for centrifugal mold filling processes and previous computer software for 3D mold filling and solidification of castings (CASM-3D for Windows). Sample simulations were implemented for mold filling processes of precision titanium castings under gravity and different centrifugal casting techniques. The computation results show that the alloy melt has a much stronger mold filling ability for thin section castings under a centrifugal force field than that only under the gravity. A "return back" mold filling manner is showed to be a reasonable technique for centrifugal casting processes, especially for thin section precision castings.     

A study on polishing of molds using hydrophilic fixed abrasive pad

The finishing process for die and mold manufacturing is very important because it influences the final quality of the products. injection molds especially need higher quality surface than general purpose dies and molds. Conventional polishing cannot reduce mold surface down to nanometer roughness efficiently because of loading and glazing. This paper focussed on the development of a fixed abrasive pad using the water swelling mechanism of polymer binder network. Self-conditioning was recognized as a long term polishing stabilization tool without any loading or glazing because water makes the fixed abrasives free by the swelling of the pad. Consequently, a stable nanopolishing process has been realized on the injection mold, based on the experimental results with a polished surface roughness of R_a 15.1 nm on D2 die steel (AISI standard).     

《铜鼓》工艺礼品的铸造

采用在橡胶模中压注液态蜡料,在蜡模组外灌注经真空处理的铸粉浆料,焙烧后,再在负压浇注台上浇注铜合金的石膏型熔模铸造工艺方法,批量生产《铜鼓》工艺礼品,获得了外观古朴仿真、纹饰清晰、表面光洁的艺术铸件;这种工艺方法生产成本较高,得到的精湛铸件还是物超所值的。     

V型船用发动机气缸体铸件排气技术的应用

针对V型船用发动机气缸体铸件尺寸相对较大,砂型和砂芯一般都使用树脂做粘结剂,且大多数采用立式全包裹砂芯浇注方式,砂型和砂芯遇高温铁液,树脂会分解产生大量气体,若不能及时排出气体,从而导致铸件产生气孔、气隔、及气缩等缺陷的问题,因此对砂芯生产工艺和排气系统进行了一系列改进,批量生产出合格铸件.     

铸型面特性对铸件表面粗糙度的影响

通过对ZL114A熔体在不同特性涂层表面的润湿角和对应铸件表面粗糙度的测量,利用润湿性模型分析了涂层中骨料材料自由能和粒度对铸件表面粗糙度的影响。结果表明,涂层表面材料自由能越低,铝合金熔体在涂层表面上润湿性越差,铸件表面粗糙度(Ra)值越低。铝合金熔体与表面自由能低的滑石粉涂层之间的润湿性随滑石粉粒度的逐渐减小呈先减小后增大的趋势,对应铸件试样表面粗糙度呈先减小后增大趋势。滑石粉粒度为43μm时,涂层和铝合金熔体间润湿角达到155°,铸件表面粗糙度(Ra)值为0.5847μm。     

用消失模工艺生产低合金钢斗齿的试验研究

用消失模铸造工艺来生产低合金钢铸件，和普通的水玻璃砂型铸件相比，在铸件的表面粗糙度和尺寸精度，以及消除某些铸造缺陷方面，都有其优越性。但也存在着铸件增碳、夹渣等新问题，需要从调整炉料配比，以及采用其他铸造和热处理的工艺措施来加以解决。     

State of the Art Treatment of Non-Ferrous Castings 3-in-l Heat Treatment Systems Combine Foundry Processes

1.Aluminum Casting Production Now andThenIt is well known that the reduction of the total weightof an automobile leads to a reduction in fuelconsumption(about0.5liters of100kilometers).Thisimproved fuel economy also reduces the CO2emissionsreleased into the atmosphere.As the size of vehicleshas grown,the overall weight has had to be decreased.The automotive industry is therefore using more andlighter metal components in order to reduce fuelconsumption and lower emissions.Production of cylin…     

State of the Art Treatment of Non-Ferrous Castings 3-in-1 Heat Treatment Systems Combine Foundry Processes

The interior of a high-pressure die-casting is of an unsatisfactory quality. Engine blocks made with this die casting process show lower specific engine performance. Pressure die-casting can hardly be heat treated for obvious reasons PSM (Precision Sand Molds) process uses sand and organic binder to generate a mold and even allows the manufacturing of complex diesel engine blocks in aluminum alloys. Combined technologies are available for semi-permanent mold castings with cores and castings made in Precision Sand Molds with organic binders. Castings are placed into the special heat treatment furnace immediately after pouting without the operations in stand alone machinery. This patented Sand Lion^R 3-in-1 technology processes hot castings and carries out three (3) foundry processes simultaneously in one (1) automated machine: 1) De-coring and sand removal; 2) Thermal sand reclamation; 3) Solution heat treatment of castings. The combination of several main casting processes is reflected in significant reductions of energy consumption, of production costs, and improving the quality of the castings. Audits in foundries using the 3-in-1 process showed an average reduction in production costs of more than 30%.     

基于航空铸造钛合金Ti-6Al-4V高速铣削参数的表面质量及切削效率优化

目的研究高速铣削参数对航空铸造钛合金Ti-6Al-4V表面质量的影响规律及交互作用,并基于高速铣削参数对表面质量和材料去除率进行优化。方法采用Box-Behnken设计和二次回归正交实验法,建立高速铣削参数与表面粗糙度的显著不失拟回归模型,获得铣削参数影响表面粗糙度的显著性差异,挖掘高速铣削参数交互作用与表面粗糙度的关系;基于表面粗糙度回归模型及材料去除率,采用遗传算法(GA),对高速铣削参数进行多目标优化。结果铣削参数影响航空铸造钛合金Ti-6Al-4V试件表面粗糙度的显著性顺序为:切削深度>每齿进给量>切削宽度>主轴转速,其中切削宽度和主轴转速、每齿进给量和主轴转速的交互作用较为明显。利用遗传算法对铣削参数优化后,Ti-6Al-4V表面粗糙度较优化前提高44%,材料去除率提高70%,遗传算法优化后的试件表面粗糙度显著降低,表面刀路行距减小,纹理平均高度降低。结论由实验验证可知,通过响应曲面建立表面粗糙度显著不失拟回归模型具有较高的预测精度,基于遗传算法优化获得的铣削参数可有效提高表面质量和切削效率,对保证航空铸造钛合金Ti-6Al-4V表面质量具有较好的指导意义。     

ZTA15大型钛合金熔模精密铸件界面反应研究

钛合金作为易氧化金属在熔融状态下非常活泼,大尺寸钛铸件在铸造过程中更容易和铸型材料发生界面反应,并对铸件表面质量产生影响。本研究采用氧化钇铸型在真空自耗凝壳炉中浇铸了大尺寸钛合金铸件,并采用SEM、XRD、EDS等方法对不同厚度试样的表层进行了检测和分析。结果发现,试样表层均存在一定厚度的氧元素扩散层,同时,还发现表层存在一定厚度的组织过渡区,最后,通过酸洗方法对试样表面反应层和组织过渡区进行了有效去除,有效提高了铸件的表面质量。     

Effect of superheat,mold, and casting materials on the metal/mold interfacial heat transfer during solidification in graphite-lined permanent molds

Heat transfer during the solidification of an Al-Cu-Si alloy (LM4) and commercial pure tin in single steel, graphite, and graphite-lined metallic (composite) molds was investigated. Experiments were carried out at three different superheats. In the case of composite molds, the effect of the thickness of the graphite lining and the outer wall on heat transfer was studied. Temperatures at known locations inside the mold and casting were used to solve the Fourier heat conduction equation inversely to yield the casting/mold interfacial heat flux transients. Increased melt superheats and higher thermal conductivity of the mold material led to an increase in the peak heat flux at the metal/mold interface. Factorial experiments indicated that the mold material had a significant effect on the peak heat flux at the 5% level of significance. The ratio of graphite lining to outer steel wall and superheat had a significant effect on the peak heat flux in significance range varying between 5 and 25%. A heat flux model was proposed to estimate the maximum heat flux transients at different superheat levels of 25 to 75 °C for any metal/mold combinations having a thermal diffusivity ratio (α _R) varying between 0.25 and 6.96. The heat flow models could be used to estimate interfacial heat flux transients from the thermophysical properties of the mold and cast materials and the melt superheat. Metallographic analysis indicated finer microstructures for castings poured at increased melt superheats and cast in high-thermal diffusivity molds.     

Characterization of zirconia-based slurries with different binders for titanium investment casting

The materials and physical properties of primary slurry are crucial to the surface quality of the finished castings,especially for high reactivity titanium alloys.The aim of this study is to investigat...     

Inference of optimal speed for sound centrifugal casting of Al-12Si alloys

True centrifugal casting is a standard casting technique for the manufacture of hollow, intricate and sound castings without the use of cores. The molten metal or alloy poured into the rotating mold forms a hollow casting as the centrifugal forces lift the liquid along the mold inner surface. When a mold is rotated at low and very high speeds defects are found in the final castings. Obtaining the critical speed for sound castings should not be a matter of guess or based on experience. The defects in the casting are mainly due to the behavior of the molten metal during the teeming and solidification process. Motion of molten metal at various speeds and its effect during casting are addressed in this paper. Eutectic Al-12Si alloy is taken as an experiment fluid and its performance during various rotational speeds is discussed.     

EFFECTS OF OXIDES IN INVESTMENT MOLD ON SURFACE PROPERTIES OF TITANIUM CASTINGS

1.IntroductionLightweight,highstrengthatambientandhightemperatures,andexcellentcorrosionresistancepropertymaketitaniumanditsalloysattractiveengineeringmaterialsinindustry.FOrexample,theapplicationoftitaniumpartsinaerospaceenginecouldnotonlyenhancetheefficiellcyofthecraft,butalsogreatlyreducethefuelconsumption.Butitsrelativelyhighmanufacturingcostshistoricallyhavelimiteditsusetohigh--techapplicationssuchasthatintheaerospacefield.Overthelasttwodecades,however,metallurgicalcastingtechnologydevel…