In the metallurgical joint industry, especially in the excellent steel metallurgical plants, there is often a steel casting workshop built at the same time as the rolling mill. This is because a large number of excellent alloy steel ingots with low plasticity are mostly required to be rolled after casting.
In industries such as machinery manufacturing, for critical components with large loads, severe operating conditions, and high strength requirements, only the casting method can be used to manufacture the blanks before they can be machined. Such as large rolling mill rolls, herringbone gears, turbine generator rotors, impellers, retaining rings, endless hydraulic press cylinders and columns, locomotive axles, crankshafts and connecting rods for cars and tractors, all of which are precision casting Into. As for the parts that are required to weigh more than 150-200 tons in the manufacture of heavy machinery, it is beyond the reach of other pressure processing methods.
Currently, the development of cars and tractors, shipbuilding, power station equipment, and the new aerospace and atomic energy industries has placed increasing demands on precision casting processes, such as requesting the supply of giant special castings, less machining or no longer Fine castings with cutting, chaotic shapes and castings with extremely high mechanical properties.
Compared with other processing methods, casting has the following characteristics: precision casting processing
The casting quality is higher than that of the casting and can accept large impact effects. The plasticity, toughness and other aspects of the mechanical properties are also higher than the castings and even higher than the rolled parts, so castings should be selected for some major machine parts.
Saving raw materials such as the crankshaft with a gross weight of 17kg for the car. When cutting the blank, the chip should account for 89% of the axle load. When the die blank is used for cutting, the chip only accounts for 30% of the axle weight, and the machining is shortened. One-sixth of the working hours.
High production efficiency For example, two hot die casting presses can be used to mold radial thrust bearings, which can replace 30 active cutting machines. When the top casting active machine produces m24 nuts, it is 17.5 times the yield of six-axis active lathes.
The free casting is suitable for single-piece small batch production, and the flexibility is relatively large. In the usual machine repair factory, it is indispensable for casting.
It is necessary to point out that casting is an initial production method, and the yield and rolling comparison are low. The level of mechanization and automation needs to be further improved.