Bevel gear is widely used in mechanical transmission, especially in automobile transmission mechanism. The traditional bevel gear processing adopts the metal cutting method and uses a special gear cutting machine to gradually process each tooth. This process method has many disadvantages. In recent years, China has begun to focus on the development of more promising plastic forming processing technology to replace the original processing methods; In particular, the precision forming technology aiming at net forming or near net forming is becoming the development direction of bevel gear processing technology.
The general plastic precision forming process is precision die forging, which is a less cutting process gradually developed from general die forging. According to the temperature of metal forming, it can be divided into cold forging, hot forging and warm forging:
(1) Cold forging is forging at room temperature, which can obtain high surface quality and good dimensional accuracy. However, its forming ability is limited, the deformation resistance is large, and the die life is low, so how to improve the die life is a major obstacle to the research of cold forging technology.
(2) Hot forging is applicable to almost all kinds of steel and can produce parts of various shapes. However, strong oxidation reaction will occur during hot forging, which will reduce the surface properties of forgings, resulting in large dimensional tolerance and subsequent machining allowance.
(3) Warm forging is a relatively new process method. Its forming temperature is usually between 650-950 ° C, which combines the advantages of hot forging and cold forging. The forgings produced by this method not only have good formability of hot forgings, but also have high-quality machined surface of cold forgings, so it is a promising process method. However, there are many factors to be considered in its process, and the research on process specification is not mature. At the same time, the cost of process design and die development is relatively higher than that of hot forging and cold forging.
The more advanced and widely used processing technology of bevel gear at home and abroad is thermal precision die forging, which can improve the strength and bending fatigue resistance of bevel gear, reduce heat treatment deformation, improve product accuracy, save materials, reduce man hours and reduce production cost. However, it still has the above disadvantages of hot forging.