Gears are one of the fundamental components used to transmit power and position. Designers hope that they can meet various requirements:
Maximum power capability
Minimum size
Minimum noise (quiet operation)
Accurate rotation/position
To meet different levels of these requirements, an appropriate degree of gear accuracy is needed. This involves several gear characteristics.
Accuracy of Spur Gears and Helical Gears
The accuracy of spur gears and helical gears is described according to the GB/T10059.1-201 standard. This standard defines and allows deviations related to the corresponding gear tooth profiles. (The specification describes 13 gear accuracy grades ranging from 0 to 12, where 0 is the highest grade and 12 is the lowest grade).
(1) Adjacent Pitch Deviation (fpt)
The deviation between the actual measured pitch value and the theoretical circular pitch value between any adjacent tooth surfaces.
Cumulative Pitch Deviation (Fp)
The difference between the theoretical sum of pitch values within any gear spacing and the actual measured sum of pitch values within the same spacing.
Helical Total Deviation (Fβ)
The helical total deviation (Fβ) represents the distance as shown in the diagram. The actual helical line is located between the upper and lower helical diagrams. The total helical deviation can lead to poor tooth contact, particularly concentrated in the contact tip areas. Shaping of the tooth crown and end can somewhat alleviate this deviation.
Radial Composite Deviation (Fi")
The total radial composite deviation represents the change in center distance when the gear rotates one full turn while meshing closely with the master gear.
Gear Radial Runout Error (Fr)
Runout error is typically measured by inserting a pin or ball into each tooth slot around the circumference of the gear and recording the maximum difference. Runout can lead to various issues, one of which is noise. The root cause of this error is often insufficient precision and rigidity of the machine tool fixtures and cutting tools.
Post time: Aug-21-2024