Forging is the titanium metal billet (excluding plate) to apply external force, so that it produces plastic deformation, change size, shape and improve the performance, used to manufacture mechanical parts, workpieces, tools or blanks of the forming process method. In addition, according to the slide movement mode, there are also slide vertical and horizontal movement (used for the forging of slender parts, lubrication and cooling and high-speed production of parts forging) mode, the use of compensation devices can be added to the other direction of the movement. The different ways mentioned above require different forging forces, processes, material utilisation, output, dimensional tolerances and lubrication and cooling methods, which are also factors affecting the level of automation.
According to the way the billet moves, forging can be divided into free forging, upsetting, extrusion, die forging, closed die forging, closed upsetting. Closed die forging and closed upsetting have high material utilisation due to the absence of flying edge. It is possible to complete the finishing of complex forgings with one process or several processes. As there is no fretting, the force area of the forging is reduced and the required load is also reduced. However, care should be taken so that the blank is not completely restricted, for this reason it is necessary to strictly control the volume of the blank, control the relative position of the forging die and measure the forging, and endeavour to reduce the wear and tear of the forging die.
According to the motion of the forging die, forging can be divided into pendulum rolling, pendulum rotary forging, roll forging, wedge cross rolling, rolling ring and oblique rolling and so on. Pendulum rolling, pendulum rotary forging and ring rolling can also be used for precision forging. In order to improve the material utilisation, roll forging and cross rolling can be used as a pre-process for long and thin materials. Rotary forging, like free forging, is also localised, and has the advantage that it can be formed with less forging force than the size of the forgings. This forging method, including free forging, processing material from the mould surface near the free surface expansion, therefore, it is difficult to ensure accuracy, so the direction of the movement of the forging die and rotary forging process with computer control, can be used to obtain the shape of the lower forging force is complex, high-precision products, such as the production of a variety of large-size turbine blades and other forgings.
In order to obtain high precision should pay attention to prevent overload at the bottom dead centre, control speed and die position. Because these will have an impact on the forgings tolerance, shape accuracy and die life. In addition, in order to maintain precision, attention should also be paid to adjusting the slider guide clearance, to ensure the stiffness, adjust the lower dead centre and the use of subsidy transmission device and other measures.
Titanium forging materials are mainly pure titanium and titanium alloys of various compositions, and the original state of the material has bar, ingot, metal powder and liquid metal. The ratio of the cross-sectional area of the metal before deformation to the cross-sectional area after deformation is called the forging ratio. Correct choice of forging ratio, reasonable heating temperature and holding time, reasonable beginning and end forging temperature, reasonable amount of deformation and deformation speed to improve product quality and reduce costs have a great relationship. General small and medium-sized forgings are round or square bars as blanks. The grain structure and mechanical properties of the bar is uniform, good, accurate shape and size, good surface quality, easy to organise mass production. As long as the heating temperature and deformation conditions are reasonably controlled, do not need a large forging deformation can be forged with excellent performance forgings.
