Forging is one of the two major components of forging (forging and stamping), which is used to exert pressure on the metal billet to produce plastic deformation to obtain a certain mechanical property, a certain shape and a dimension forging. The forging can eliminate the defects such as the loose casting in the smelting process, optimize the microstructure, and the mechanical properties of the forgings are generally superior to those of the same material because of the complete metal streamline. The important parts with high load and severe working conditions in the related machinery, besides the simple shape can be used for rolling plate, profile or welding parts, the forging is more adopted.
According to the deformation temperature, forging can be divided into hot forging (the forging temperature is higher than the recrystallization temperature of the billet metal), forging (the recrystallization temperature of the forging temperature is lower than that of the metal) and cold (ambient temperature). The recrystallization temperature of the steel is about 460 ℃, but the 800℃ is widely used as the dividing line, and the heat forging is higher than 800 ℃, which is called forging or semi heat forging between 300~800℃.
Closed die forging and closed-type upsetting
Because there is no flying edge, the material utilization is high. It is possible to finish finishing the complex forgings with a process or several processes. As there is no flying edge, the force area of the forgings is reduced and the required load is reduced. However, it should be noted that the blanks can not be completely restricted, so we should strictly control the volume of the billet, control the relative position of the forging die and measure the forgings to reduce the wear of the forging die.
Movement of blanks
According to the movement mode of billet, forging can be divided into open, upsetting, extruding, die forging, closed die forging, closed-type upsetting forging.
1, the forging. The use of impact or pressure to make the metal in the upper and lower two iron (anvil) between the deformation to obtain the required forgings, mainly manual forging and mechanical forging two kinds.
2. Die forging. Die forging is divided into open die forging and closed die forging. Metal billet in a certain shape of the forging die in the compression deformation to obtain forgings, but also can be divided into cold heading, roll forging, radial forging and extrusion and so on.
3, closed-die forging and closed-type upsetting because there is no flying edge, the material utilization is high. It is possible to finish finishing the complex forgings with a process or several processes. As there is no flying edge, the force area of the forgings is reduced and the required load is reduced. However, it should be noted that the blanks can not be completely restricted, so we should strictly control the volume of the billet, control the relative position of the forging die and measure the forgings to reduce the wear of the forging die.
Movement Mode of forging die
According to the movement mode of forging die, forging can be divided into rolling, swing forging, roll forging, cross wedge rolling, rolling ring and inclined rolling, etc. Rotary, swing forging and rolling ring can also be used for precision forging process. In order to improve the utilization ratio of materials, roll forging and rolling can be used as the front process of slender materials. The same as the rotary forging of forging is also a local forming, its advantage is compared with the forging size, less forging force can be achieved under the circumstances. This method of forging, including open forging, expands from the mold surface to the free surface, therefore, it is difficult to guarantee the precision, so the movement direction of the forging die and the spinning process of the computer control, the use of lower forging force can be used to obtain complex shape, high precision products, such as production of many varieties, large size of the turbine blades and other forgings.