# Influence of pitch cone angle change on forging difficulty of spiral bevel gear

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.

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.

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