Sand casting of automobile engine cylinder head

In the new era of the 21st century, China’s automobile industry is booming and has become a pillar industry of national economic development. However, China’s automobile industry still faces the problems of unreasonable industrial structure, low technical level and weak independent research and development ability. One of the key points restricting the improvement of independent R & D capability is the lack of rapid manufacturing means and related common technology development platform.

Auto parts have the characteristics of complex structure, large load, high dimensional accuracy and poor working conditions. Driven by the rapid development of the global economy, it is also required to update its products quickly and have a short production cycle, so as to meet the flexible and changeable market demand. Although China is the largest producer of sand castings, due to the relatively backward casting conditions, the current situation of sand casting molds is difficult to adapt to the current situation, so it puts forward urgent problems to be solved for China’s casting industry. As the most complex and key part of the engine, the cylinder head of automobile engine needs the corresponding professional sand casting technology to develop and produce. For the development of automobile engine cylinder head, the traditional method is to trial produce and improve wood mold and metal mold, which has long R & D cycle and high cost. Generally, the traditional development cycle of automobile engine cylinder head is 6-8 months, and the development cost of gravity die for automobile engine cylinder head is about 1 million / pair. This traditional development method seriously restricts the improvement of enterprise R & D capability and brings huge R & D costs. It does not adapt to the realistic situation of rapid upgrading of automobile engines and the urgent need to realize industrialization of key parts.

Sand casting is the most widely used casting technology in the foundry industry. Rapid sand casting technology is to use rapid prototype parts to replace the traditional metal pattern or wood pattern, and then use the rapid sand casting process CAD system for mold design, combined with the traditional sand casting process to quickly make castings. Among them, SLA technology is a relatively mature light curing prototype technology. The pattern and core box are made by SLA prototype, and the mold is made by combining the traditional parting and assembly processes of sand mold, which forms a complete method of producing and processing rapid sand mold casting mold. Because the SLA pattern and core box in the rapid sand casting process based on SLA prototype can be reused, the cost is reduced and the quality of sand castings is improved. Therefore, the rapid sand casting process based on SLA prototype is especially suitable for automobile sand castings with complex shape and requiring sand core molding, such as automobile engine cylinder block, cylinder head, intake and exhaust manifold, etc. However, due to the following reasons:

(1) SLA prototyping and optimization are highly professional; (2) The core problem of rapid sand casting based on SLA is the establishment of mold (module) CAD model. The realization of this process should not only adapt to the characteristics of SLA process, but also be based on the knowledge, experience and principles of sand casting process. At present, the modeling function of casting CAE software is limited, and there are deficiencies in data sharing between CAD and CAE. These factors make the establishment of mold CAD model a highly professional technical work, which is difficult for ordinary technicians.

Therefore, taking the cylinder head of an automobile engine as an example, the above rapid sand casting process route is used to design the mold, and the professional casting CAE analysis software ProCAST is used to inversely solve the important process parameter of heat transfer coefficient in sand casting, and then simulate the whole filling and solidification process of several schemes to determine the optimal gating system and riser structure, To provide guidance for the design of gravity casting die for actual automobile engine cylinder head. This research can effectively shorten the time of mold design and reduce the dependence of traditional experience design. It has high reference value for the development of new products and the production of other single and small batch parts.

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