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Coated Gear Shaving Cutter
Common normal length
The external gear is the common normal distance measured between
the two outer tooth surfaces of adjacent teeth; the internal gear
is the common normal distance measured between the two outer tooth
surfaces of several adjacent tooth slots, which is called the
common normal length. For involute spur gears, the common normal
length is calculated in the end plane, and the calculation formula
is: Wt=mtcosat[(k-0.5)x+zinvat]+2mtxtsinat (x should have its own
symbol, k is the number of cross teeth). The involute helical tooth
(or herringbone tooth) cylindrical gear is measured in the normal
plane, and its value is: Wn=Wtcosβb. The length of the common
normal line is an important indicator for checking the depth of
cutting teeth and determining the level of accuracy.
The length of the common normal can be directly checked from the
relevant table.