The pitch cone angle is a very important parameter in the geometry of spiral bevel gear, which is directly related to the number of large and small gears and the axial intersection angle between them. Its value will affect whether the gear teeth interfere axially, the forming result and the mold drawing. Take it as a variable parameter and carry out the simulation test under the condition of constant modulus, pressure angle, helix angle and tooth width, And analyze the results. The process is as follows:
Set the number of teeth of the large gear of spiral bevel gear as 41 and the modulus as 5. When the number of teeth of the small gear changes (the number of small and medium teeth are 11, 15, 20, 25, 30, 35 and 41 respectively), the pitch cone angle of the large and small gear will change accordingly; In addition, according to the stroke load curve, the degree of precision forging difficulty is measured according to the loading force in the final forming stage of the forging. In this way, each different pitch cone angle corresponds to a forming loading force, and the results are drawn into a two-dimensional diagram, that is, the influence curve of pitch cone angle on precision forging difficulty can be obtained. The relationship and fitting line between pitch cone angle of large wheel and forging loading force are shown in Figure 1.
Using the same method, the cone angle of small wheel joint is simulated, and the results are shown in Fig. 2.
It can be seen from Figure 1 and Figure 2 that the pitch cone angle is linearly related to the forging difficulty. The loading force of large wheel precision forging decreases with the increase of pitch cone angle, and the forging loading force of small wheel increases with the increase of pitch cone angle. The reason is analyzed. When the modulus and number of teeth of large wheel remain unchanged, the volume of large wheel does not change much, and the influence of pitch cone angle on the loading force is very significant, With the increase of pitch cone angle, because the axial distance of spiral bevel gear decreases and the shape is closer to the face gear, the friction decreases under this influence and the loading force decreases gradually; For the small wheel, the modulus remains unchanged. Due to the increase of the number of teeth, the volume of the small wheel increases obviously. The influence of the increase of the volume on the loading force is much greater than that of the increase of the pitch cone angle on the loading force. Therefore, the loading force increases with the increase of the pitch cone angle and volume, indicating that the pitch cone angle has a great influence on the forging process of spiral bevel gear.
The die cavity is the main stress position of the forged spiral bevel gear. Under the force of the die, the blank fills the cavity. The pitch cone angle is directly related to the depth of the cavity. From the data of the large wheel, the smaller the pitch cone angle is, the deeper the cavity depth is, the more materials need to flow, and the greater the loading force to promote the material flow. Due to the influence of the volume factor of the small wheel, Volume is the main influencing factor of small wheel forging simulation, so the influence of small wheel pitch cone angle will not be discussed temporarily.