实型铸造的回顾、现状与前景

通过对实型铸造（消失模铸造）的回顾和现状的分析，找出了当前存在的差距，并提出发展实型铸造的建议。     

消失模铸造工艺及其工程设计要点

简要介绍了消失模铸造工艺的特点及生产工艺流程,根据其特点进一步介绍了消失模铸造厂的工程设计要点,将白区与黑区分开布置,在满足消防要求的同时,降低了消防投入。为以后消失模铸造项目的设计提供借鉴和参考。     

中国实型铸造的现状与发展前景

实型（消失模）铸造在我国虽已有３３年历史，但真正获得较快发展的是８０年代末中国铸造协会实型铸造专业委员会成立（当时仅１８家会员单位）后，尤其是近几年发展更为迅速。据不完全统计，现今在我国从事这项新技术研究和应用的约有１１０余家单位，是１９８８年中国铸造协会实型铸造专业委员会成立时的６倍。其中：研究院所和高等院校有１４家，消失模铸造原辅材料和专用设备生产厂点有１５家。１９９７年中国实型（消失模）铸件产量近２５８００ｔ，比１９９５年产量增加１倍（其中９８％是黑色金属铸件），但仅占现有生产能力的１６％；可见，中国消失模铸造的发展前景是十分可观的。     

实型铸造车间黑区铸造线的设计要领

文中作者结合自己的成功设计实践,详细阐述了大批量生产箱体铸铁件的消失模车间黑区铸造线的非标设计原则、要领及诀窍.     

实型铸造系统设计

从六个方面阐述了实型铸造系统设计的思路和作法：砂箱的形状及其抽真空应考虑的问题；砂箱进出填砂／紧实工位的两种形式；机械振动台的频率、振幅、振动方式的选择和橡胶空气弹簧刚度的估算方法等。     

实型铸造法的关键基础技术

实型铸造法的关键基础技术包括:模样的材料及成形、涂料、型砂的振动充填、金属液的充填。国内外的研究和经验表明,使用铸造低密度EPS珠粒模样;用具有高的强度、良好的涂挂性和触变性、高的透气性的涂料;干砂的填充密度高,各向压力一致;金属液的充填平稳快速。是实型铸造法获得成功的关键。     

High Cr white cast iron/carbon steel bimetal liner by lost foam casting with liquid-liquid composite process

Liners in wet ball mill for mineral processing industry must bear abrasive wear and corrosive wear,and consequently,the service life of the liner made from traditional materials,such as Hadfield steel ...     

Porosity of aluminum alloy in lost foam casting process

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｌｏｓｔｆｏａｍｃａｓｔｉｎｇ (ＬＦＣ) ｐｒｏｃｅｓｓｉｓｃａｌｌｅｄａｓｔｈｅ 2 1ｓｔｃｅｎｔｕｒｙｔｅｃｈｎｏｌｏｇｙ .Ｉｔｓｆｏｒｍｉｎｇｉｓｄｉｆｆｅｒｅｎｔｆｒｏｍｔｈａｔｏｆｔｈｅｃｏｎｖｅｎｔｉｏｎａｌｅｍｐｔｙ ｃａｖｉｔｙｃａｓｔｉｎｇｍｅｔｈｏｄ[1,2 ].ＦｏｒａｌｕｍｉｎｕｍａｌｌｏｙｉｎＬＦＣ ｐｒｏｃｅｓｓ,ｐｏｕｒｉｎｇｔｅｍｐｅｒａｔｕｒｅｏｆａｌｕｍｉｎｕｍｍｅｌｔｉｓｍｕｃｈｈｉｇｈｅｒｔｈａｎｔｈａｔｏｆｔｈｅｅｍｐｔｙ ｃａｖｉｔｙ…     

Permeability of coating in the lost foam casting process

This study measured the pressures developed during a filling experiment using molten grey iron in the lost foam casting (LFC) process. The measured pressures included back pressure and permeable pressure. The back pressure is created in-mould from the metal-foam interface. The permeable pressure was measured on the mould side of the coating, when gases introduced from the decomposing EPS were permeating through the coating. The permeable pressure reflected the permeability of the coating while filling molten iron. Variables, which included particle sizes, types of binders, weight per cent of binder in coatings, influenced the permeability of coating at room temperature and at casting temperature.

Coatings made from flaky alumina developed a greater total length of pore channels than those made from angular silica. Increasing the particle size of the refractory increased the permeability of the coating at room temperature. The highest permeable pressure was measured when the particle size was 74 μm and acrylic resin was used as a binder. The optimum binder content was less than 1% for flaky alumina and acrylic resin binder. The optimum coating thickness was less than 0.5 mm to develop a maximum permeable pressure associated with a minimum back pressure in the mould.     

Simulation of mould filling in lost foam casting process

In this investigation, an algorithm was developed to calculate the gas pressure at the melt/foam interface (gap) owing to degraded foam during mould filling in the lost foam casting process (LFC). The effect of back-pressure on mould filling was modelled using a new experimental function by the addition of a three-dimensional volume of fluid (3D-VOF) function. The molten flow and free surface were simulated using the solution algorithm-VOF (SOLA-VOF) numerical technique. To simulate the three-dimensional incompressible flow in the LFC, the pressure boundary conditions, heat transfer and foam gas pressure effect were modified. Finally, in order to verify the computational results of simulation, a thin plate of grey iron was poured into a transparent foam mould. The mould filling process was recorded using a 16 mm high-speed camera, then images were analysed frame-by-frame to obtain foam depolymerisation and gap volume during mould filling. The comparison of experimental and numerical results in the LFC filling sequence showed good agreement, which confirms the accuracy of the model. IJCMR/447     

Status quo and development trend of lost foam casting technology

Lost foam casting（LFC）technology has been widely applied to cast iron and cast steel.However,the development of LFC for Al and Mg alloys was relatively slower than that for cast iron and cast steel.The application of LFC to Al and Mg alloys needs more effort,especially in China.In this paper,the development history of LFC is reviewed,and the application situations of LFC to Al and Mg alloys are mainly discussed.Meanwhile,the key problems of LFC for Al and Mg alloys are also pointed out.Finally,the prospects for LFC technology are discussed,and some special new LFC technologies are introduced for casting Al and Mg alloys.In future,the development trends of green LFC technology mainly focus on the special new LFC methods,metal material,coating,heat treatment,new foam materials as well as purification technology of tail gas,etc.     

Microstructure and mechanical properties of lost foam cast 356 alloys

Microstructure and mechanical properties of lost foam cast aluminum alloys have been investigated in both primary A356(0.13% Fe) and secondary 356(0.47%). As expected, secondary 356 shows much higher content of Fe-rich intermetallic phases, and in particular the porosity in comparison with primary A356. The average area percent and size(length) of Fe-rich intermetallics change from about 0.5% and 6 μm in A356 to 2% and 25 μm in 356 alloy. The average area percent and maximum size of porosity also increase from about 0.4% and 420 μm to 1.4% and 600 μm, respectively. As a result, tensile ductility decreases about 60% and ultimate tensile strength declines about 8%. Lower fatigue strength was also experienced in the secondary 356 alloy. Low cycle fatigue(LCF) strength decreased from 187 MPa in A356 to 159 MPa in 356 and high cycle fatigue(HCF) strength also declined slightly from 68 MPa to 64 MPa.     

Formation mechanism of gas cavity defects in lost foam iron castings

The formation mechanism of gas cavity defects in lost foam iron castings was studied by laboratory and in-plant experiments. By scanning electronic microscopy and spectral analysis in the laboratory, carbon concentration and coating residues were observed on the bottom and/or the wall of the gas cavity defects. This indicates that the entrapped foam pyrolysis products are the cause of the gas cavity defects, which is quite different from the causes of the same defect in open cavity mould castings. In-plant measurements show that pyrolysis products were entrapped into the molten metal by erratic metal filling. Also, the metal temperature near the defect area, where metal filled last, is close to or even lower than the solidus temperature of the metal. The cold metal trapped the pyrolysis products inside the casting, resulting in the gas cavity defect. Based on the above observations, new process parameters were used, and the casting scrap rate dropped significantly from 25 to 5%. IJCMR/469     

Heat transfer characteristics of lost foam casting process of magnesium alloy

1 Introduction The growing demand for mass reduction in aerospace and automotive industries has greatly increased the magnesium application. Currently, casting is the main industrial forming method for magnesium alloys, but the lag of research and develop…     

控制压力冒口技术在消失模生产中的应用

通过对粘土砂铸造生产工艺技术和消失模铸造生产工艺技术的摸索对比,应用控制压力冒口技术成功地扩大了消失模铸造工艺技术在生产中的应用,提高了铸件工艺出品率,降低了铸件废品率,提高了企业的经济效益和市场竞争力     

Numerical simulation and analysis of mould filling process in lost foam casting

In lost foam casting （LFC） the foam pattern is the key criterion, and the filling process is crucial to ensure the high quality of the foam pattern. Filling which lacks uniformity and denseness will cause various defects and affect the surface quality of the casting. The influential factors of the filling process are realized in this research. Optimization of the filling process, enhancement of efficiency, decrease of waste, etc., are obtained by the numerical simulation of the filling process using a computer. The equations governing the dense gas-solid two-phase flow are established, and the physical significance of each equation is discussed. The Euler/Lagrange numerical model is used to simulate the fluid dynamic characteristics of the dense two-phase flow during the mould filling process in lost foam casting. The experiments and numerical results showed that this method can be a very promising tool in the mould filling simulation of beads＇ movement.