"Modulus" refers to the ratio of pitch t between adjacent teeth on the same side to pi (m = t/π) in millimeters. Modulus is one of the most basic parameters of modular gear teeth. The larger the modulus, the higher and thicker the gear teeth. If the number of teeth of the gear is fixed, the radial dimension of the wheel is larger. Modular series standards are formulated according to the requirements of design, manufacture and inspection. For spur gears, there are differences among normal module mn, end-face modulus ms and axial modulus mx, which are all based on the ratio of their respective pitches (normal pitch, end-face pitch and axial pitch) to pi, also in millimeters. For bevel gears, the modulus can be divided into big end modulus me, average modulus mm and small end modulus m 1. For cutting tools, there is a corresponding tool modulus mo, etc. Standard modulus is widely used. In metric gear transmission, worm transmission, synchronous toothed belt transmission, ratchet, gear coupling, spline and other parts, the standard modulus is the most basic parameter. It plays a fundamental role in the design, manufacture and maintenance of the above parts (see cylindrical gear drive, worm drive, etc.). ).
Gear type:
A gear is a toothed wheel, which transmits the rotary motion of one shaft to another shaft through its meshing action, and transmits motion or torque between the two shafts. There are many kinds of gears, which are divided into parallel shafts, orthogonal shafts and intersecting shafts according to the gear shafts.
Modulus: a pointer indicating the size of gear teeth. The modulus of a pair of meshing gears must be the same, otherwise the tooth specifications of the two gears are different, and smooth operation cannot be realized. Explaining the modulus in words is: the ratio of the middle diameter to the middle diameter, usually (㎜). Modulus is usually in metric system, and English system is pitch diameter, that is, the ratio of gear teeth to pitch diameter, which is the reciprocal of module in a sense. The unit is (teeth/inch).
Modulus: m = d/n Diameter pitch: PD = n/d
Pitch circle: it is a theoretical circle. In a pair of meshing gears, pitch circles must cut each other.
Pitch circle diameter: it is the diameter of pitch circle, d.
Pressure line: When two gears are in contact, the direction perpendicular to the contact surface means that the normal load is usually transmitted along the pressure line.
Pressure angle pa: This is the angle between the common tangent of two gear pitch circles and the pressure line. Pressure angles are generally 14.5 degrees and 20 degrees. At present, a pressure angle of 20 is often used to prevent interference.