How is the "grade" of gears divided?

When you say "grade", you should mean the accuracy grade of the gear ... (The gear here is an involute cylindrical gear).

The machine standard stipulates the accuracy grade of 12, and the numbers 1, 2, 3, ... 12 are arranged in the order of high accuracy, and most of them are 5 ~ 9 accuracy grades. In addition, according to the different requirements of motion accuracy, transmission smoothness and load distribution uniformity, the tolerances of each accuracy level are divided into three groups in turn, namely, the first tolerance group, the second tolerance group and the third tolerance group.

The accuracy grade of gears should be determined according to the economic and technical indicators such as purpose, service conditions, transmission efficiency and peripheral speed.

The fifth gear is a precision gear.

Machining method: generating machining is carried out on a precision gear machine tool with small cycle error. Finally, the tooth surface is precisely ground, and the large gear is ground or shaved after precision hobbing. The roughness of tooth surface reaches 0.4-0.8.

Scope of use: precision gear for indexing mechanism; For high-speed gears, there are high requirements for running stability and noise; High-speed steam turbine gear, etc.

The 7-stage gear is a gear with relatively high precision.

Machining method: generating machining is performed on a high-precision gear machine tool. Cutting non-quenched tooth surface with high precision tool; Quenched gears need finishing (grinding, scraping, grinding, etc.). ). The tooth surface roughness reaches 1.6.

Scope of use: used for gears with high speed, small load or reverse rotation; The feed gear of the machine tool needs to move together with the mating gear; Medium speed reduction gear; Aircraft landing gear; Herringbone medium-speed gear, etc.