Titanium forging is a forming method that applies external force to titanium metal blanks (excluding plates) to cause plastic deformation, change size, shape and improve performance, and is used to manufacture mechanical parts, workpieces, tools or blanks.
According to the forging in different temperature regions, according to the different forging quality and forging process requirements, it can be divided into three forming temperature regions: cold forging, warm forging and hot forging. Originally, there was no strict limit to the division of this temperature range. Generally speaking, forging in a temperature range with recrystallization is called hot forging, and forging without heating at room temperature is called cold forging.
During low temperature forging, the dimensional change of forgings is very small. Forging below 700 ℃, there is little scale formation and there is no decarburization on the surface. Therefore, as long as the deformation can be within the forming range, cold forging is easy to obtain good dimensional accuracy and surface finish. As long as the temperature and lubrication are well controlled, warm forging below 700 ° C can also achieve good accuracy. During hot forging, due to the small deformation energy and deformation resistance, large forgings with complex shapes can be forged. To obtain forgings with high dimensional accuracy, hot forging can be used in the temperature range of 900-1000 ℃. In addition, we must pay attention to improve the working environment of hot forging, forging die life (hot forging 2-5 thousand, warm forging 1-2 thousand, cold forging 20,000-50,000) is shorter than other temperature range forging Yes, but it has great freedom and low cost.
The billet is deformed and hardened during cold forging, so that the forging die is subjected to high loads. Therefore, it is necessary to use a high-strength forging die and a hard lubricating film treatment method to prevent wear and adhesion. In addition, in order to prevent the blank from cracking, intermediate annealing is performed when necessary to ensure the required deformability. In order to maintain a good lubrication state, the blank can be phosphatized. In the continuous processing with bar stock and wire rod, the cross-section can not be lubricated at present, and the possibility of using phosphating lubrication method is being studied.
Forging can be divided into free forging, upsetting, extrusion, die forging, closed die forging, and closed upsetting forging according to the movement method of the blank. Closed die forging and closed upset forging have no flash, so the material utilization rate is high. With one process or several processes, it is possible to finish the finishing of complex forgings. Since there is no flash, the bearing area of ​​the forging is reduced, and the required load is also reduced. However, it should be noted that the blank cannot be completely restricted. For this reason, the volume of the blank should be strictly controlled, the relative position of the forging die and the measurement of the forgings should be controlled to reduce the wear of the forging die.
According to the movement mode of the forging die, forging can be divided into swing rolling, swing rotary forging, roll forging, cross wedge rolling, ring rolling and cross rolling. Swinging, swinging forging and rolling rings can also be processed by precision forging. In order to improve the utilization rate of materials, roll forging and horizontal rolling can be used as the front-end processing of slender materials. Rotary forging, which is the same as free forging, is also partially formed. Its advantage is that it can be formed even when the forging force is small compared to the size of the forging. In this forging method, including free forging, the material expands from the vicinity of the die surface to the free surface during processing. Therefore, it is difficult to ensure accuracy. Therefore, the computer can control the movement direction of the forging die and the spinning process for lower The forging force can obtain products with complex shapes and high precision, such as forgings of steam turbine blades with many varieties and large sizes.
Forging equipment’s die movement is inconsistent with the degree of freedom. According to the characteristics of the bottom dead center deformation limitation, forging equipment can be divided into the following four forms:
Restricted form of forging force: hydraulic press which directly drives the slider.
Quasi-stroke limitation method: hydraulic press to drive the crank connecting rod mechanism.
Stroke limitation method: mechanical press with crank, connecting rod and wedge mechanism driving the slider.
Energy limitation method: screw and friction press using screw mechanism.
In order to obtain high accuracy, care should be taken to prevent overload at the bottom dead center, and control the speed and mold position. Because these will affect the tolerance of forgings, shape accuracy and forging die life. In addition, in order to maintain accuracy, attention should also be paid to adjusting the slider rail clearance, ensuring rigidity, adjusting the bottom dead center and using auxiliary transmission devices and other measures.
In addition, according to the slider movement mode, there are vertical and horizontal movement of the slider (for forging of elongated parts, lubrication and cooling, and high-speed production of forging parts). The use of compensation devices can increase movement in other directions. The above methods are different. The required forging force, process, material utilization, output, dimensional tolerance and lubrication and cooling methods are different. These factors are also factors that affect the level of automation.