Cold forging is simply the process of forging without heating the blank. The materials for cold forging are mostly aluminum and some alloys, copper and some alloys, low carbon steel, medium carbon steel and low alloy structural steel with good plasticity. Cold forging can strengthen metal and improve the strength of parts. The cold forged parts have good surface quality and high dimensional accuracy, which can replace some cutting processes.
Cold forging is carried out at room temperature, and hot forging is carried out at high temperature; The working hardness of cold forging is hard while that of hot forging is soft; The pressure of cold forging during molding needs a large pressure, while the pressure of hot forging during molding may be relatively small; The processing precision of cold forging after forging can be high, while that of hot forging after forging is low; The work of cold forging is suitable for small ones, while the work of hot forging can be a big thing; The surface of the workpiece after cold forging is smooth, while the surface of the workpiece after hot forging is rough;
Compared with hot forging, cold forging saves expensive heating equipment, and has the advantages of material saving and high processing accuracy. However, it is also limited by process requirements, so it has higher requirements for mold design and manufacturing, equipment pressure, etc.
When the head is cold forged, its forging size will not change much. If the head is placed below 700 ℃ for forging, its surface will not show any decarburization. That is to say, as long as the whole deformation is within the range of forming requirements, cold forging can actually improve the surface smoothness and dimensional accuracy of the head.
When the head is hot forged, the resistance to deformation and deformation capacity are actually relatively small, which is more suitable for large forgings with complex shapes.
The main function of the head is to exert external force on the metal plates to cause the metal plates to deform, thus changing the shape and size, and improving the performance significantly. It is more suitable for processing and manufacturing mechanical workpieces. In fact, the heads can be divided into many types in forging, and there are many characteristics. When the forging temperature is between 400 ℃ and 800 ℃, the head's resistance to deformation will rapidly decrease, and the deformation will also be effectively changed. Because the temperature region is different, the forging quality and forging related requirements will also be different. The head is one of the components of the boiler in the pressure vessel.