Gear is an important part of the transmission of cars, heavy trucks, motorcycles and other vehicles

Gear is an important part of the transmission of cars, heavy trucks, motorcycles and other vehicles. There are about 18 ~ 30 tooth shaped parts in each automobile gearbox. The quality of the gear has a significant impact on the noise, stability and service life of the automobile. Therefore, there are high requirements for the surface quality, dimensional accuracy and comprehensive mechanical properties of gears. Gear processing methods are diverse, such as gear rolling, powder metallurgy, precision forging, cold extrusion, cutting and so on. At present, the most common gear manufacturing process in China is “blanking forging blank annealing or normalizing tooth profile and profile cutting carburizing heat treatment finishing”. Tooth profile cutting methods such as gear hobbing, gear shaping, gear shaving, gear honing and gear grinding are widely used at home and abroad. Although the cutting gear product has high dimensional accuracy and good surface quality, it has high production cost and equipment occupancy, low material utilization and processing efficiency, and the metal streamline is cut off in the cutting process, which reduces the strength, toughness, wear resistance and service life of the gear. In recent years, with the rapid development of automobile, heavy truck and equipment manufacturing industry and the intensification of competition in the international market, the production and manufacturing of parts and components must improve the R & D, design and manufacturing level, improve the product material utilization, quality accuracy and performance, reduce the production cost and reduce the environmental pollution caused by the processing and manufacturing process to improve the market competitiveness of products. In order to meet the high requirements of gear processing industry for production efficiency, manufacturing precision and green low carbon, gear processing is developing towards high efficiency, high precision and green environmental protection.

Plastic forming technology is characterized by high yield, high quality and low consumption, which is very in line with the strategic development direction of advanced manufacturing. Precision plastic forming technology can effectively reduce cutting, reduce production cost and improve product quality and accuracy. Gear precision plastic forming technology refers to the gear manufacturing technology that the gear tooth is directly formed from the blank to obtain the complete tooth shape, and the tooth surface can be used without cutting or only a little finishing. The characteristics of gear precision plastic forming technology are as follows: improve the gear structure, the metal fiber structure is continuously and evenly distributed along the tooth profile, the structure is dense, the grain is small, and there are few micro defects; Excellent comprehensive mechanical properties, good bending strength, contact fatigue strength and impact resistance; High material utilization rate, high dimensional accuracy of formed gear, and no or only a small amount of mechanical cutting is required in the follow-up; It has long service life, reduces heat treatment deformation, and improves the wear resistance and stability of the gear during operation; The production efficiency is high. Compared with traditional cutting, the equipment occupies less. The use of manipulator can realize the automation of production process, which greatly improves the production efficiency.

There is a certain gap between China’s gear manufacturing industry and western developed countries in process design and development and equipment manufacturing. A series of technical problems need to be solved urgently, such as low level of precision plastic forming process, unstable part quality, low dimensional accuracy, poor surface quality, high scrap rate, dependence on imports of high-end equipment and low service life of molds. At present, domestic enterprises have realized large-scale industrial production by using floating die closed cold extrusion for planetary gears and half shaft gears with small modulus, size and pressure angle, composite forming process of warm (hot) forging and cold finishing for large half shaft gears and combined teeth, and cold extrusion for gear ring parts by using shunt forging theory. However, when forming large module spur gear with the existing process, the tooth tops of the upper and lower surfaces of the gear are not fully filled, the forming load is large, the die is easy to crack, the die has no draft angle, resulting in serious wear, low service life, and poor tooth profile and tooth direction accuracy of the formed parts. Therefore, the domestic gear manufacturing industry must develop a set of practical forming process to enhance its market competitiveness.

The popularization and application of computer technology in manufacturing industry has subversively changed the mode of product development. Traditional product development can only rely on the designer’s own experience for preliminary design, and then debug and modify in the process of small batch trial production through a large number of trials and errors. The whole development cycle consumes a lot of time, manpower and funds. Using CAD, CAE and CAM technology, product development designers can repeatedly carry out process simulation, analysis and evaluation before trial production, and finally select the optimal design, which greatly shortens the product development cycle and reduces the development cost. At present, the market competition is fierce, the products are updated frequently, the structure is complex, the quality accuracy requirements are high and standardized, and the product R & D personnel must complete the process development and tooling design in a short time. Mastering and making effective use of computer technology can promote the rapid development of domestic advanced manufacturing industry.

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