Name of each part of cylindrical gear (take spur gear as an example):
l) Pitch circle diameter d ‘, graduation circle diameter D – the two tangent circles on the connecting line O1O2 are called pitch circles. For a single cylindrical gear, as the reference circle for calculating the size of each part when designing and manufacturing cylindrical gear, it is also the circle of dividing teeth, which is called Indexing circle. Standard cylindrical gear d = D ‘.
2) Addendum circle diameter Da – the circle passing through the top of the gear tooth is called the addendum circle.
3) Root circle diameter DF – the circle passing through the root of the tooth groove is called the root circle.
4) Tooth top height h a tooth root height h f tooth height H – the radial distance between the tooth top circle and the indexing circle is called the tooth top height; The radial distance between the indexing circle and the tooth root circle is called the tooth root height; The radial distance between the tooth top circle and the tooth root circle is called the tooth height. The dimensional relationship is: H = HA + HF
5) Tooth thickness s, groove width e, tooth pitch P – the arc length of each tooth on the indexing circle is called tooth thickness; The solitary length of each tooth slot on the dividing circle is called the slot width; The arc length between the corresponding points of two adjacent tooth profiles on the indexing circle is called tooth pitch. The pitch of two meshing cylindrical gears must be equal. The dimensional relationship between tooth pitch P, tooth thickness s and groove width e is: P = S + e, and S = e of standard cylindrical gear.
6) Modulus – if Z represents the number of teeth of the cylindrical gear, then: the circumference of the indexing circle = π d = ZP, that is, d = ZP / π. Let P / π = m, then d = MZ, where. It is called modulus. Because the pitch P of the two cylindrical gears must be equal, their modulus is also equal.
For the convenience of cylindrical gear design and processing, the value of modulus has been standardized. As listed in Table 1. The greater the modulus, the greater the height and thickness of the gear teeth and the greater the load they bear. Under the same conditions, the greater the modulus, the greater the cylindrical gear.