During the cold precision forging of spiral bevel gear big wheel, the blank deforms under the loading force of the die. With the increase of the contact area between the die and the blank, the loading force gradually increases. In order to describe the relationship between the loading force and the displacement of the upper die, that is, the travel load curve. The travel load curve of the upper die for the forging of spiral bevel gear big wheel is shown in the figure.
It can be seen from the figure that from the starting position, the upper die starts to move and put pressure on the blank. Due to the interaction of forces, the loading force on the die gradually increases. At the beginning, the increasing trend of the loading force is slow, the slope of the approximate straight line is small, and the increment of the loading force changes with the displacement is small. In this process, the die displacement continues to increase, and the blank deforms under the loading of the die, Filling the mold cavity, which is the forging stage; The displacement of the die continues to increase. When it is about 1.5mm, the increasing trend of the loading force becomes acute, and the slope of the approximate straight line increases. The loading force increases rapidly with the increase of the displacement. Until the displacement of the upper die reaches about 1.7 ~ 1.8mm, the curve of the loading force fluctuates. The fluctuation position represents that the upper die contacts the lower die, and there is a part of blank between the upper and lower dies, As the displacement of the upper die continues to increase, the blank is extruded and formed into forgings. After the full contact between the upper and lower dies, the loading force begins to increase rapidly, which is the final stage of forging.
According to the stroke load curve of the spiral bevel gear wheel, the loading force required for forging the spiral bevel gear can be analyzed. In the final stage, the loading force reaches about 3800000n, which is converted into a press of about 380 tons. Considering the safety problem, the tonnage of the press should be higher according to a certain retention coefficient.
The final loading force in the forming process of spiral bevel gear large wheel forging can guide the tonnage of the press and the material selection of the die. In addition, since the upper die is selected as the load reference, it can be seen from the loading curve that the stroke load curve is still increased after the contact between the upper die and the lower die, indicating that the upper die has a loading force on the lower die, which should be avoided in the actual forging process, Prevent excessive force between molds from causing damage to molds.