Forging, the forging mechanical pressure is applied to the metal blank, to produce plastic deformation in order to obtain a certain mechanical properties, a certain shape and size of forging processing method. Forging (forging and stamping) the two part of. The forging can eliminate the defects such as the casting state during smelting process, optimize the microstructure and the mechanical properties of the forgings are better than those of the same material. In the machine, the load is high, the working conditions of the important parts, in addition to the shape of the more simple available rolling plate, profile or welding, more than the use of forging.

Classification of forging

according to the movement of blank, forging can be divided into free forging, upsetting, extrusion, forging, closed die forging, closed type forging.

1, free forging. The use of impact force or pressure to make the metal in the upper and lower two iron (anvil) to produce deformation in order to obtain the required forgings, mainly manual forging and mechanical forging two.

2, die forging. Forging and open die forging and closed die forging. Metal blank in a certain shape of forging die cavity inner compression deformation for forging and divided into cold heading, roll forging, radial forging and extruding.

Two, according to the deformation temperature, forging and can be divided into hot forging (forging temperature is higher than the recrystallization temperature of the billet metal), warm forging (forging temperature lower than the recrystallization temperature of the metal) and cold forging (at room temperature). The recrystallization temperature of the steel is about 460, but it is generally used as the dividing line at 800, which is a hot forging at 800 or 800 degrees centigrade.

According to the movement of the blank, forging can be divided into free forging, upsetting, extrusion, forging, closed die forging, closed upsetting. Closed die forging and closed upsetting because no flash, high material utilization rate. With a process or a few steps may complete the fine processing of complex forgings. As a result of the absence of the flying edge, the stress area of the forging is reduced, and the required load is also reduced. But should be careful not to be restricted completely blank, therefore to strictly control the blank size, relative position control of forging die and forging of were measured efforts to reduce die wear.

According to the motion mode of forging die, forging can be divided into rotary pendulum, rotary forging, roll forging, cross wedge rolling, ring rolling and cross rolling etc.. Rotary forging, rotary forging and rolling pendulum ring forging process is also available. In order to improve the utilization ratio of material, roll forging and cross rolling can be used as the front working procedure of slender material. The same as the free forging is also a part of the rotary forging, it has the advantage of the same size, compared with the forging force can also be achieved in the case of small forging. Including free forging, the forging, machining material from the mold surface near to a free surface expansion. Therefore, it is difficult to guarantee the accuracy, so will die of the direction of motion and rotary forging process by computer control, can lower the forging force obtained complex shape, high precision products, such as the production of many varieties, large size of the turbine blade forging.

Forging equipment of mold and degrees of freedom is not consistent, according to the lower dead point deformation limit characteristics and forging equipment can is divided into the following four types:

Limit of the form of the forging force: the hydraulic pressure of the oil press directly drives the slider.

Quasi - stroke limit mode: oil pressure driven crank connecting rod mechanism.

The stroke limit mode: the mechanical press of the crank, connecting rod and wedge mechanism.

Energy limitation: the use of screw and friction press.

In order to obtain high accuracy should be taken to prevent the bottom dead center overload, control the speed and position of die. Because these will have an impact on the forging tolerances, shape accuracy and die life. In addition, in order to maintain the accuracy should also note slider guide rail gap adjustment, ensure the stiffness, adjust the bottom dead center and utilization subsidies transmission device and other measures.

In addition, according to the movement of the slider, the slider is vertical and horizontal motion (for the elongated parts of the forging, lubrication cooling and high speed production of parts forging), the use of the compensation device can increase the other direction of movement. The method is different from the method of forging force, working procedure, the use of the material, the output, the dimension tolerance and the lubrication cooling way are not the same, these factors also affect the level of automation.

Forged materials and processes

The forging material is mainly carbon steel and alloy steel components, followed by aluminum and magnesium, copper, titanium and its alloys. The material has its original state bar, ingot, metal powder and liquid metal. The ratio of the cross-sectional area of the metal to the cross-sectional area after the deformation and the deformation is more than that of the forging ratio. The correct selection of forging ratio, reasonable heating temperature and holding time, reasonable starting temperature and final forging temperature, reasonable deformation and deformation speed are very significant to improve product quality and reduce cost.

In general, small and medium forgings are used as a round or square rod as the blank. The grain structure and mechanical properties of the bar are uniform, good, and the shape and size of the material is accurate, the surface quality is good, so that the mass production is easy to be organized. As long as the reasonable control of the heating temperature and deformation conditions, no large forging deformation will be able to forge a good performance of the forgings.

Only for large forging ingot. The ingot is cast, there are large columnar grains and osteoporosis center. Therefore, it is necessary to break through the large plastic deformation, the columnar grain is fine grain, and the loose and compacted, to obtain the fine metal structure and mechanical properties.

The sintered powder metallurgy, which is pressed and burned, is formed by the non flying side die in the hot state.