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