Twelve precision levels are specified, which are sequentially represented by numbers 1, 2, 3, ... 12 in order of accuracy from high to low, and most commonly used are 5 to 9 levels of precision. In addition, according to the requirements of the accuracy of the motion, the smoothness of the transmission and the uniformity of the load distribution, the public service of each accuracy level is sequentially divided into three groups, the first public service group and the second public The service group and the III public service group.
The accuracy level of the gear should be determined according to the use of the transmission, the conditions of use, the transmission efficiency and the peripheral speed, and other economic and technical indicators.
The 5th gear is fine.
Processing method: processing on a fine gear machine with very small periodic error. The tooth surface is finally finely ground, and the large gear is ground or ground with fine hobbing, after grinding or shaving. The tooth surface roughness reaches 0.4-0.8.
Scope of use: Gears for fine indexing mechanisms; gears for high speed and high requirements for smoothness and noise; gears for high speed turbines.
The 7-stage gear is a relatively high precision class.
Processing method: processing on a high-precision gear machine. Non-quenched tooth surfaces are cut with high-precision tools; quenched gears require finishing (grinding, shaving, grinding, etc.). The tooth surface roughness reached 1.6.
Scope of use: gears for high speed, small load or reverse rotation; feed gears for machine tools, gears with matching motion requirements; medium speed reduction gears; aircraft gears; medium speed gears for herringbone teeth.
