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Graphical Parameters For Gears
Nov 26, 2018

1. Number of teeth Z The total number of teeth of a gear.


2. The product of the modulus m tooth distance and the number of teeth is equal to the circumference of the fractal circle, that is, the Pz=πd, z in the formula is the natural number, and the pi is the unreasonable number. The condition that D is a rational number is that the p/π is a rational number, called the modulus. namely: M=p/π


3. The tooth size of the split circle diameter d gear is determined by this circle as a benchmark, D=MZ 4. The calculation formula of the diameter of the tooth top circle and the diameter of the tooth root circle can be introduced by the formula of the height of the tooth top and the height of the groove in the diameter of the head round, which is the diameter of the top circle and the groove of the root circle: da=d+2ha df=d-2hf=mz+2m=mz-2x1.25m=m (z+2) =m


4. The diameter of the tooth top circle and the diameter of the tooth root circle df can be calculated by calculating the diameter of the top circle and the diameter of the tooth root circle by the formula of high tooth top and high tooth root: da=d+2ha df=d-2hf=mz+2m=mz-2x1.25m=m (z+2) =m (z-2.5)


5. Modulus Z: The fractal Circle of gears is the reference for the design and calculation of the dimensions of each part of the gear, while the circumference of the gear fractal Circle is =πd=z p, so the diameter of the score circle is d=z p/π because the pi is an unreasonable number in the upper formula, it is not convenient to position the fractal circle as the datum. PI is artificially defined as a number of simple values, and this ratio is called modulus (module), expressed in M, even if its unit is mm. So: modulus m is a basic parameter that determines the size of the gear. The gear modulus with the same number of teeth is large, and its size is large. For ease of manufacture, inspection and interchange use,  The modulus value of the gears has been standardized.


6. Split Circle diameter d: In gear calculation, a circle must be specified as a datum circle for dimension calculation, defined as a circle with a product of modulus multiplied by the number of teeth. It doesn't actually exist in the gears, it's just a defined circle. Its diameter and radius are represented by D and R respectively, and the value is only related to the product of modulus and number of teeth, and the modulus is the end modulus. independent of the displacement coefficient. The circle in the standard gear is equal to the groove width and tooth thickness (regardless of the tooth side clearance) is the split circle. The standard gear drive coincides with the knuckle circle. However, in the variable gear, the tooth groove and tooth thickness on the split circle will no longer be equal. If the distribution circle of high displacement gear transmission in the variable gear transmission is still coincident with the joint circle.  However, the gear transmission of the angular displacement will be separated by the split circle and the joint circle.


7. Pressure angle α--in the two-gear joint round tangent point P, the two-tooth profile curve of the common normal (that is, the force direction of the tooth profile) and two round of the common tangent line (that is, the instantaneous direction of motion at the p point) clip the sharp angle called the pressure angle, also known as the meshing angle. For a single gear, it is a tooth-shaped angle. The pressure angle of the standard gear is generally 20 ". The bearing capacity of small pressure angle gears is small, while the large pressure angle gears, although the bearing capacity is high, the bearing load increases when the transmission torque is the same, so it is only used in special cases.

8. Basic parameters and expression of tooth profile: Bb%h[1]wfu,b-r0 According to the standard gear design rules, as shown in Figure 2 groove Contour calculation reference diagram. +e "A[|B0



9. Basic parameter diagram:


10. Modulus and number of teeth are the most important parameters of gears. In the case of constant number of teeth, the larger the modulus, the larger the gear teeth, the stronger the ability to resist breakage, of course, the larger the gear wheel billet, the larger the space size; In the case of constant modulus, the larger the number of teeth, the more gentle the involute, the thicker the tooth top round teeth, the thickness of the tooth root round teeth correspondingly thicker.



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