1.Helix angle:
It refers to the angle between the teeth of helical gear and the axis. Helix angle is a special feature of helical gear, which does not exist in spur gear, that is, spur gear. Generally speaking, the helix angle of helical gear we usually refer to refers to the helix angle on the indexing cylindrical surface. The larger the helix angle is, the greater the coincidence degree is, which is more conducive to stable movement and noise reduction. Everything has two sides. Although increasing the helix angle brings many advantages, the axial force generated during operation also increases. Therefore, the size of the helix angle should depend on the quality requirements and processing accuracy of the work. Generally, it is 8-25. If there are special requirements for noise, a larger value can be taken according to the situation.
Judgment of helix rotation direction: first, we make the gear axis vertical. If the height on the right side of the helix is right rotation; On the contrary, the left height of the helix is left-handed.
2.End face and normal face parameters:
End face: the plane perpendicular to the gear axis, and the parameters on the end face are generally added with subscript t;
Normal plane: the plane perpendicular to the helix. The parameters on the normal plane are generally subscript n.
(1) Pitch and modulus: = t = π
(2) Pressure angle: generally, the parameters in the normal plane are standard parameters.
a. Correct meshing condition: the helix angle must be equal in size and opposite in direction. The normal modulus m and the normal pressure angle are required to be equal respectively.
b. Because the calculation formula of the straight end face of the helical gear is the same as that of the straight end face of the helical gear, it can be used to calculate the size of the straight end face of the helical gear.