The prototype of low pressure casting process can be traced back to the last century. Is suitable for aluminum alloy 1917 in France, in Germany in 1924 put forward the application, but did not form large-scale industrial production. Start production for the purpose of business is after world war ii in 1945, founded by the British Mr Lewis the aru mas library company, started to produce rain pipes, beer containers, etc. For the next 50 years, Austria and Germany began to produce cylinder head. Jersey in the United States in 1958 where las road vision it on small car engine parts (cylinder head, body, gear box), a large number of aluminum alloy castings, and adopt the low pressure casting method. It for low pressure casting method is still widely used are indispensable, especially in the automobile industry all over the world has caused great repercussions. Low pressure casting method was introduced into our country is around 1957, but the real cause the attention of the industry, began to undertake a variety of research, the introduction of equipment from began around the year 1960. But this epoch-making process method broke the previous common sense, there is almost no riser, and has been established as a "technical" gravity type gold casting technology compared with the difficulty of the completely different, so the industry's response is cold.
Under this situation, the 1961 light vehicle with air cooling of cylinder head production be the beginning of the low pressure casting method in practical application in our country. Future development very quickly, after overcame several technical problems, using low pressure casting method has high material utilization, and the advantages of easy to realize automatic note soup, to auto parts as the center, gradually established a light alloy castings, the main casting solid status. In the production of aluminum alloy casting, low pressure casting products have accounted for about 50%, and with its huge production capacity and good quality is famous. Product expand to auto parts, such as cylinder head, cylinder block, clutch cover, brake drum, wheel hub, intake manifold, etc. Especially after 1970, a large number of applications on the hub, and the car lightweight and improve performance requirements, such as in the past has never been complex internal quality and mechanical properties, under the strict requirements of the use of cylinder head, cylinder block and a gradual increase.
Since is used by a large number of low pressure casting process has been more than 30 years, has established the position of one of the important execution of work of aluminum alloy castings. Especially in the role of cylinder head is huge, low pressure casting are still is the mainstream method in the future.
From an empty cold small engine cylinder head start, to the function of water, pump, expand, DOHC and the increased weight of materials, and the shape is more and more complex, and also increase the wall thickness change, the difficulty of casting also increased year by year, at the same time in order to reduce the cost for productivity improvement, consider the mold is 2 pieces, process improvement, dynamic exchange mold die faster and combined with the operation, the cooling control and pressure control technology is also increased year by year, has emerged, including handling and assembly of sand core, fully automated line, it is also free from high temperature work, improve the working environment.
According to the above content, consider the following cylinder head casting technology of project:
1) improve the strength of materials (including gasoline engine, diesel engine cylinder head of aluminum alloy propulsion)
2) improve productive (improve the synchronization of control technology, the post-processing line, fully automated production line
3) other varieties a small amount of production measures (including mold preparation process of cutting, neutron modelling and post-processing
The compact production line design)
4) to shorten development time
5) the continuation of skills (coating, casting conditions on the adjustment, etc.)
About item 1), how to cooling is the type of a key, but previous technology in low pressure casting is
Difficult to apply, so that more suitable for use gravity casting. Case 2 is therefore maximize the lower die casting
Bit advantages to overcome the problem of practical examples. Countries in Europe and the cylinder head is still the main casting gravity casting process, so in order to expand the market must solve the problem in the future.
Regarding item (2) and (3), it is with the progress of FA technology are bound to the development of the problem. Considering the castings of high strength and high production requirements, under controlled conditions will become more complicated than and compact so high degree of freedom structure composite can maintain a high level of production line.
About item 4), the key lies in the need in the early design stage, and the user common development, and actively using CAE technology.
Last 5) is the most urgent project, the more advance automation and unmanned, the more important this issue. Because it is difficult to quantitative digital, and related to the experience of project is more, so the real skill education and inheritance is very important. At the same time in order to achieve the quantitative control of basic research and development are also important.