The theory of metal liquid forming is often called casting, casting forming technology has a long history. As early as more than 5,000 years ago, our ancestors were able to cast copper and bronze products. Casting is the most widely used metal liquid forming process.
It is a method of pouring liquid metal into a mold cavity to obtain a certain shape of blank or part after its cooling and solidification. In machine equipment, the proportion of liquid forming parts is very large, in machine tools, internal combustion engines, mining machinery, heavy machinery, liquid forming parts of the total weight of the 70%~90%, in the automobile, tractors accounted for 50%~70%, in the agricultural machinery accounted for 40%~70%.
The liquid-forming process is so widely used because it has the following advantages: (1) can produce the internal cavity, the shape is very complex blank.
such as a variety of boxes, machine bed, cylinder body, cylinder head and so on. (2) The technology flexibility is big, the adaptability is wide. Liquid forming parts of the size of almost unlimited, its weight can be from a few grams to hundreds of tons, the wall thickness can be from 0.5mm to 1m or so. All metal materials which can be dissolved into liquid in industry can be used for liquid forming.
For ductile iron with poor plasticity, liquid forming is the only way to produce its blanks or parts. (3) Low cost of liquid forming parts. Liquid forming can directly use scrap parts and chips, equipment cost is lower.
At the same time, the liquid forming part processing allowance is small, saves the metal. However, the process of metal liquid forming is many, and it is difficult to control accurately, so the casting quality is not stable.
Compared with the same material forgings, the liquid forming microstructure is loose and the grains are coarse, and the internal Easy to produce shrinkage, shrinkage, porosity and other defects. Its mechanical properties are lower. In addition, the labor intensity is big, the condition is bad.
has excellent mechanical, physical properties, it can have a variety of different strength, hardness, toughness and combination of comprehensive performance, but also can be a combination of one or more special properties, such as wear-resistant, high temperature and low temperature, corrosion resistance.
Casting weight and size range are very wide, the lightest weight of only a few grams, the heaviest can reach 400 tons, the wall thickness of the thinnest only 0.5 mm, the thickest can exceed 1 meters, the length can be from a few millimeters to more than 10 meters, can meet the requirements of different industrial sectors.