# Analysis of stroke load curve in forming process of spiral bevel gear

Analyze the stroke load curve of the forming process of the driven spiral bevel gear of the automobile rear axle under different forging temperatures. Figure 1 shows the stroke load curve of the cold machining process of the spiral bevel gear. The forging temperature is normal temperature, and the forging temperature is set as 20 ℃ in the simulation process; Figure 2 shows the stroke load curve of the warm machining process of spiral bevel gear, in which (a) (b) (c) (d) (E) (f) correspond to the stroke load curve when the forging temperature is 300 ℃, 400 ℃, 500 ℃, 600 ℃, 700 ℃ and 800 ℃ respectively; Figure 3 shows the stroke load curve of spiral bevel gear during hot working, in which (a) (b) (c) (d) correspond to the stroke load curve when the forging temperature is 900 ℃, 1000 ℃, 1100 ℃ and 1200 ℃ respectively.

It can be seen from figures 1, 2 and 3 that the shape of the stroke load curve of the spiral bevel gear at different temperatures is basically the same. After the load starts to be loaded, the load is roughly proportional to the stroke. When the stroke reaches about 16mm, the load will increase rapidly until the load reaches the maximum value when clamping. The reason for this phenomenon is that when the stroke reaches 16mm, the upsetting is basically completed and the spiral bevel gear blank has filled the whole cavity, At this time, the deformation is mainly the forming of tooth shape, and the excess metal material flows into the flash groove. At this time, the load will increase rapidly with the increase of stroke. The maximum load of cold working is 13500 kn and that of warm working at 300 ℃ is 12400 kn, which is not significantly lower than that at normal temperature.

Figure 4 shows the relationship curve between maximum load and temperature. It can be seen from the figure that when the temperature is from 300 ~ 600 ℃, the maximum load decreases with the increase of temperature. At this time, there is a linear relationship between temperature and maximum load. At 600 ~ 800 ℃, the maximum load decreases rapidly with the increase of temperature. At 800 ~ 1200 ℃, the maximum load decreases gradually with the increase of temperature, and its slope is less than 600 ~ 800 ℃. With the increase of temperature, the plasticity of metal gradually increases, the yield strength decreases and it is easy to form. However, the metal of spiral bevel gear blank in hot working process will form a layer of oxide film on its surface, which needs subsequent cutting to remove the oxide layer, resulting in waste of materials and energy, and even affect the quality of forgings.

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