In modern machinery, gear transmission is the most widely used mechanical transmission mode. Its function is to transmit the motion and power between two shafts. Especially in the automotive industry, gear has been a large number of specialized production, in the long-term production practice, has formed a whole set of production technology.
Typical gear processing technology
Machining gear with cutting method is a typical gear processing technology. The production process is generally divided into: gear rough processing → gear surface processing → heat treatment process → gear surface finishing. The specific process is: forging or bar forming gear blank → rough machining, cutting more surplus → semi finishing, turning, hobbing, gear shaping, etc. → heat treatment, tempering, carburizing and quenching, high frequency quenching → finishing, finishing benchmark, finishing tooth profile, etc.
The gear processed by this technology can reach a high precision, generally up to level 6, after honing, up to level 5 or above, which can be used in high-speed, low-noise working environment. In the long-term practice, it is found that the failure ratio of the gear body is higher than that of the tooth surface, mainly bending fatigue fracture and overload fracture.
Precision forging technology of gear
With the development of CNC precision machining technology, precision forging technology and precision mold manufacturing technology have been widely used in the mass production of gear parts. Precision forging process is divided into hot precision forging and cold heading forging. The mature hot precision forging process is called “one heat two forging”, that is, after the gear is hot forged and cut, it uses the residual heat of the forging to finish, so the precision of the hot forged gear is about 8-9 levels.
Cold heading forging, also known as block forging, is an advanced precision forming technology without flash. When the accuracy of die tooth profile reaches level 6, the accuracy of gear can reach level 8-9 under the condition of mass production. Such gears can meet the use requirements of trucks and light vehicles, and can be used in low-speed, heavy load, high noise working environment. In the long-term use process, it is found that the failure mode of this kind of gear, the ratio of tooth surface failure is higher than that of tooth body failure, mainly for wear and pitting.