亚洲AV无码专区亚洲AV不卡,亚洲欧美日韩中文字幕在线不卡,亚洲精品成人区在线观看,无码AV免费精品一区二区三区,日韩av一级在线观看,亚洲精品国产情侣AV在线

Development of large scale casting process

Casting is a kind of process that: smelt the metal into a liquid that meets the requirements and pours it into the mold; Cooled and solidified, and cleaned; obtain castings with a predetermined shape, size and properties. Because rough casting is almost shaped the purpose of free machining or a small amount of processing is achieved, that reduced costs. Casting is one of the basic processes of modern machinery manufacturing industry.

The processing technology of casting has been used for 6000 years ago. China entered the peak period of bronze castings between 1700 and 1000 BC. The process has reached a very high level. Simuwu tripod made in Shang Dynasty with weight of 875 kg is the representative of the ancient casting products.

Early castings were mostly tools or utensils for agricultural production, religion, and life. At that time the development of casting process is parallel with the development of pottery. 

Casting tripod with 270kg that was the earliest cast iron pieces in the world appeared in 513 BC. Europe began to produce cast iron pieces around the eighth century. The appearance of cast iron expanded the scope of application of castings. For example, in the 15th to the 17th century, Germany, France and other countries have laid a lot of cast iron pipe used to drink water for residents.

In 20th century, casting developed fast. One of the important factors is the progress of product technology requiring a variety of mechanical properties of castings better with good mechanical processing performance. Another reason is the mechanical industry itself and other industries such as chemical, instrumentation and other development provided good material conditions to the foundry industry. The development of the detection ensures the improvement and stability of the casting quality providing the conditions for the development of casting theory. The invention of electron microscopy makes it possible to come into the microscopic world of metal. 

During this period a large number of new cast metal materials with superior properties were developed. Such as ductile iron, malleable cast iron, ultra-low carbon stainless steel, aluminum-copper alloy, Al-Si alloy, aluminum and magnesium alloy, titanium, nickel-based alloy. A new process for the processing of gray cast iron was invented, so that the adaptability of the casting is more extensive.

After the 1950s, wet sand high pressure modeling came out. Chemical hardened sand molding, core making, negative pressure modeling and other new technology make it possible to cast more accurate and good finishing. Labor conditions in the casting workshop were also greatly improved.

Significant progress in the foundry industry since the 20th century, especially Gray cast iron and chemical hardening sand molding. These two new technologies changed the traditional method that was used for thousands of years, opened up new areas of the casting process and had a significant impact on the competitiveness of castings.