What Is Precision Forging?

Precision forging refers to the forming technology that requires only a small amount of processing or no further processing to meet the requirements of the part after the part is forged. Precision forging is an important part of advanced manufacturing technology, and it is also a widely used part manufacturing process in the automotive, mining, energy, construction, aviation, aerospace, weapon and other industries. Precision forging not only saves materials and energy, reduces processing procedures and equipment, but also significantly improves productivity and product quality, reduces production costs, and thus improves the market competitiveness of products.

The ability to form large and complex structural forgings is an important reflection of a country's industrial technology level and comprehensive national strength. The main structural forging materials used in important manufacturing fields such as aerospace, aerospace, and energy are mostly high-temperature alloys, titanium alloys, and high-strength alloy steels. These materials have been successfully used in aircrafts and gas turbines, and have improved the power-to-weight ratio of engines. Increasing the speed of the aircraft and the efficiency of the gas turbine play a vital role. With the rapid development of China s economy and national defense, the demand for large and complex forgings has increased sharply, such as the overall frame of the aircraft, the overall leaf disc of the engine, large blades and discs of gas turbines and gas turbines. the above. However, titanium alloys and superalloys are both expensive metal materials and special materials that are difficult to process and deform. On the one hand, the machining performance of such materials is particularly poor; on the other hand, due to the large deformation resistance, high deformation temperature, and narrow temperature range of deformation, generally only rough forgings can be used before machining, which leads to excessive High manufacturing cost, which limits and affects the use of materials to a certain extent. However, the emergence of hot precision forging technology, represented by hot die forging and isothermal forging, has opened an important way to solve the near-net-shape forging of difficult-to-deform materials such as titanium alloys and high-temperature alloys, and provides a new method for the production of large and complex forgings. Means ^[1]

Many precision forging processes have been applied to production. According to different forming temperature, it can be divided into hot precision forging, cold precision forging, warm precision forging, composite precision forging, isothermal precision forging, etc. ^[2]

With the development of the manufacturing industry, the requirements for precision forged parts are getting higher and higher, and the research and development of precision forging technology are also put forward. At present, the main directions of precision forging technology research are as follows.

(1) Continuous process innovation. In order to meet the requirements of formed parts and reduce production costs, new precision forging processes with high forming accuracy, long mold life and high production efficiency need to be continuously developed.

(2) Development of composite technology. With the continuous improvement of the technological requirements of formed parts, a single precision forging is difficult to meet the requirements. This requires the development of composite forming processes, combining forging processes with different temperatures or different process methods, and complementing each other to complete the manufacturing of a part. The precision forging process can also be combined with other precision forming processes such as precision casting, precision welding and other processes to improve the application range and processing capacity of the precision forming process.

(3) Knowledge-based process design. With the continuous development of precision forging process, the process design is becoming more and more complicated. In order to improve the reliability and efficiency of process design, the development of knowledge-based expert systems is an important research direction for future precision forging process design ^[2]

In order to meet the requirements of precision forging technology, precision forging equipment needs to have the following characteristics.

1) With good rigidity, the deformation of the machine itself during the deformation process is small, and the dimensional accuracy of the forged workpiece is guaranteed.

2) It has a precise guide mechanism to ensure the accuracy of mold clamping.

3) With multi-cylinder action ability, to achieve the requirements of precision forging multiple mold movements.

4) With automatic monitoring and detection functions of production processes.

Common equipment for hot precision forging includes high-energy screw presses, electro-hydraulic hammers, hot die forging presses, etc. Common equipment for cold precision forging includes cold forging presses, cold extrusion machines, cold upsetting machines, and cold swing rolling machines Wait. There are mainly two ways to purchase precision forging equipment in China in the early stages: importing precision forging equipment or production lines from well-known foreign companies such as Swiss Hatebur, British Hewelco, Italian SACMA, Japanese Komatsu, German Schuler, and American National Renovation of domestic general forging equipment. Because imported equipment is expensive, and the accuracy and reliability of the retrofit equipment is poor, it is urgent to research and develop domestic precision forging equipment. In recent years, domestic precision forging equipment has been greatly developed. Among them, Beijing Institute of Mechanical and Electrical Technology, Jinan Second Machine Tool Research institutes and enterprises including Shanghai Forging Machine Tool Factory, Shanghai Forging Machine Tool Factory, Qingdao Forging Machine Tool Factory, and Qingdao Forging Machine Tool Factory have successfully developed and developed a series of precision forging equipment and have been put into engineering applications ^[3]

Whether it is forward simulation or reverse simulation, it can be boiled down to the trial and error method of design result verification using numerical simulation technology. The basic idea is still the same as the traditional trial and error method, except that the verification methods used are different. Modifications to the unreasonable design need to be proposed by the designer based on experience. The degree of automation of the design process is still low. In order to improve the efficiency and reliability of precision forging process and die design, in recent years scholars at home and abroad have conducted a lot of research on the optimization design of precision forging process technology and die, and have made great progress. The precision design of precision forging process and mold is a calculator that generally uses process parameters or the shape of the mold as design variables, the shape or physical properties of the workpiece as the objective function, and the finite element method as the objective function. The efficient optimization algorithm is used to automatically optimize the process parameters and mold shape. At present, the commonly used optimization methods include: sensitivity analysis and optimization algorithms based on gradients, and genetic algorithms based on global optimization.