Industrial definition: the graduation circle of a gear is the benchmark for designing and calculating the dimensions of all parts of the gear. The circumference of the graduation circle of the gear =πd=z p, so the diameter of the graduation circle is d=z p/π.

Chemical definition: molar ratio. (For example, the chemical formula is R2O n SiO2, and n is the ratio of the number of moles of SiO2 to R2O, which is called the modulus of R2O n SiO 2. )

Because π in the above formula is an irrational number, it is not convenient for extended data to locate the cyclotron as the benchmark. In order to facilitate calculation, manufacture and inspection, the ratio of p/π is artificially defined as some simple values, which are called modulus and expressed in m, that is, its unit is mm. So I have to:

Modulus m is the basic parameter to determine the gear size. Gears with the same number of teeth have large modulus and large size. In order to facilitate manufacturing, inspection and interchangeable use, gear modulus values have been standardized.

The standardized numerical reference of modulus is GB 1357-87. The first series is 0. 1, 0. 12, 0. 15, 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.8, 1,/kloc-0.

The second series includes 0.35, 0.7, 0.9, 1.75, 2.25, 2.75, 3.75, 4.5, 5.5, 6.5, 7, 9,1/kloc-0+.

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