(1) Selection of diameter DP of spiral bevel gear blank
Spiral bevel gear blank belongs to round cake forging, so the diameter dimension calculation formula of blank is:
Of which: ‘
DP – billet diameter preliminarily determined in theory;
VP – volume of spiral bevel gear blank;
VJ – forging volume, JV = 354900m3;
VF – volume of flash plus punching skin, FV = 47492.5mm3;
M – ratio of height to diameter of spiral bevel gear blank, generally M = 1.8 ~ 2.2, here 1.8;
δ — The fire consumption rate is 1.0% according to Table 3.1.
After calculation, VP = 406416.425mm3, substituted into the formula, d’p = 66mm, and DP = 70mm is selected according to the standard specification.
(2) Spiral bevel gear blank length LP
Blanking length formula:
Where, AP is the cross-sectional area of spiral bevel gear blank.
Substituting the diameter PD = 70mm into formula 3-2, LP is 105mm.
| Heating method | δ /％ |
| Chamber type oil furnace | 33.5 |
| Continuous oil furnace | 2.5～3.0 |
| Chamber type gas stove | 2.5～3.0 |
| Continuous gas stove | 2.0～2.5 |
| Resistance furnace | 1.5～1.0 |
| High frequency heating furnace | 1.0～0.5 |
| Contact electric heating | 1.0～0.5 |
| Chamber type coal furnace | 3.5～4.0 |
The material of driven spiral bevel gear blank of automobile rear axle is 20CrMoH alloy steel, and the density is 7.85g/cm3. Finally, the forging mass m = 2.7kg, and the spiral bevel gear blank mass m = 3.3kg.