1. Three hot topics in the scientific research of lost foam casting in North America  Europe

One of the hot topics: to reduce  eliminate the defects of lost foam aluminum alloy casting.

Among the 45 reports  papers, there are as many as eleven articles on how to reduce  eliminate defects in aluminum alloy casting,  several papers are on how to eliminate the most troublesome problem of lost foam casting aluminum alloy castings-carbon mixed Cold barrier defect. The carbon mixed cold barrier defect refers to the "cold barrier" that appears at the place  two metal streams meet  has  been wetted  melted. Especially for complex castings such as engine cylinder heads  cylinder blocks, the carbon mixed cold barrier can easily cause liquid to leak inside the castings,  cause metal fatigue fracture.

Therefore, experts in many fields discuss how to eliminate carbon mixed cold insulation defects  the following different perspectives: ① According to how to improve the fluidity of aluminum alloys to reduce carbon mixed cold insulation defects; ② According to the improvement of coating permeability, the coating can be discharged in time Qualified aluminum alloy die castings are obtained  the decomposition products of the metal front; ③The precision casting company has selected many processing methods to move the carbon impurities to non-critical positions,  according to the specific position of the pouring port  the adjustment of the shape in the sand box. Specific location,  vacuuming during metal casting to reduce carbon impurities; ④ Mercury Marine Corporation of the United States adopts new technology of pressurization in the sand box, which effectively solves the defects of cold insulation  shrinkage  improves aluminum castings Air tightness.

Among these papers, the content of the article "The Development of Lost Foam in the United States-New Improvements to EPS Beads" by Professor Fred  the American company StryroChem is the most worthy of reading. This article explains that the success of lost foam aluminum alloy casting in North America  Europe is the result of long-term cooperation with scientific research institutions, precision casting companies  raw material procurement manufacturers.

In the mid to late 1990s, StyroChem developed a polystyrene (EPC) product T180D that is more suitable for cast aluminum parts. Its foaming medium is composed of three isomers of pentane (n-pentane). , Isopentane  cyclopentane). The combined pentane can make EPS beads easier to foam to a low density state (17.6g/L). The lower the density, the less the residue of vaporization  cracking in the precision casting process.

At the same time, the company also developed a patented organic brominated additive in EPS. The additive can quickly reduce the EPS molecular weight when the temperature is uniformly increased, so that gas  liquid by-products can be discharged  the ceramic coating in advance,  it is  easy to form carbon defects in the molten metal. StyroChem has also built a comprehensive lost foam foundry to explore whether organic brominated additives can change the composition of EPS degradation products. Tests have shown that under certain conditions, it can reduce  even completely remove carbon  die castings. Miscellaneous. At present, EPS raw materials containing brominated additives developed by the company have been promoted  used in lost foam casting aluminum enterprises.

Hot spot two: foaming mold  white zone molding process.

Among the forty-five reports  the content of the article, there are ten reports describing the foaming mold  white zone molding process. Among the most recommended contents are: the popularization of the CAD/CAE/CAM process of foaming molds, the block process of cylinder block  cylinder head,  the bonding process of multiple mold pieces.

Hot spot 3: Lost foam casting CAE  rapid prototyping process.

The use of advanced CAE analysis software  rapid manufacturing technology for lost foam casting has become a development trend. There are 6 articles related to casting simulation  rapid manufacturing. The following aspects are involved: ①For the foaming mold of complex castings such as cylinder heads, computer dynamic simulation is used to simulate the process of filling the mold cavity with foam beads,  the simulation results are used to guide the placement position of the shooting gun  the layout of the exhaust plug ;②The simulation of the temperature field of the foaming mold is used to guide the design of the mold wall thickness  intake  exhaust; ③The simulation simulation of the lost foam casting process, that is, the foam mold disappearing process  the molten metal filling process are simultaneously presented, Germany MAGMA company Developed  designed a special simulation software for lost foam casting,  has simulated  simulated complex castings such as boxes, crankshafts, cylinder blocks  large covers,  the results have been praised by customers with five stars; ④The method of direct production  processing of foam prototypes with CNC ,  then use the lost foam casting process to quickly provide casting samples; ⑤Develop  design a variety of methods that use rapid mold making to shorten the mold opening cycle of the foam mold.

2. Basic situation of lost foam casting companies in North America  Europe

The Michigan Conference  AFS2002 Conference in the United States mainly reflect the new achievements of lost foam casting in the United States. The Paderborn Conference in Germany demonstrated the overall level of lost foam casting in developed countries such as Germany, the United States, Italy  the Netherlands after entering the 21st century. Developed countries such as the United States, Germany,  Italy are committed to the research of lost foam casting with the active participation of many automobile groups. After a long process accumulation, they have entered the mass production of aluminum alloy  black aluminum alloy castings. period. Among the forty-five reports, more than ten reports are comprehensive evaluations of lost foam casting. Among them, the report of "Using the advantages of lost foam processing technology to develop the high value-added casting market" by Parker Stroom of the United States is the most abundant.

Mr. Parker has been engaged in lost foam casting in the United States for more than 20 years. He has participated in several major lost foam casting projects in the United States, such as GM's Saturn project, GM Powertrain project  its Mercury Marine project,  later served as the technical director of Vulcan. His report listed twelve successful aluminum alloy lost foam casting companies  eleven black aluminum lost foam casting successful companies.

Combined with Mr. Parker’s report  referring to the Lost Foam Casting Company  Supply  Demand Manual officially published by the American Precision Casting Society in 2002, the top ten companies  enterprises in North America  Europe that use lost foam casting to produce aluminum alloy castings are cited. The main products  output of the top ten companies of black alloy castings.

In 2001, the total output of lost foam aluminum alloy castings by six companies in the United States exceeded 80,000 tons. Among them, there would be four companies with an annual output of aluminum alloy castings exceeding 10,000 tons. It can be said that the current output of aluminum alloy castings produced by lost foam casting in the United States has a great tendency to exceed the output of black alloy castings. In every casting evaluation activity held by AFS in recent years, many lost foam aluminum alloy castings have been selected. Since the first half of 2003, ASF has selected 10 excellent castings, of which two lost foam castings will be nominated for the gold list: one is an aluminum alloy 4-cylinder cylinder block  cylinder head produced by GM2Powertrain. The other is a car pressure pipe provided by VehcomCastManufacturing, Canada.