The size of the outer shunt gap is determined by the distance between the lower end face of the upper die and the upper end face of the lower die at the end of extrusion forming. The size of the outer shunt gap is changed by changing the relative position of the upper and lower dies. The influence of the outer split gap on the metal forming force of bevel gear to be studied is based on the determination of the inner split gap. The flash generated at the split gap needs to be directly removed by the trimming machine in the subsequent processing. Considering the convenience of the subsequent machinist and the waste of materials, combined with figure 1 (relationship curve between the size of the inner split gap and the forming force), Set the inner shunt gap to 5mm to study the outer shunt gap. It is studied that the best position of the outer shunting surface is at the position where the upper end face of the outer shunting surface is 2mm lower than the lower end face of the inner shunting surface. Therefore, on the basis of the research, the value of the inner shunting gap is fixed to 5mm, and the volume of the preform remains unchanged. By changing the size of the outer shunting gap, numerical simulation is carried out to observe the metal forming force of the bevel gear and the filling quality of the bevel gear tooth shape.
The size of the outer split gap also has an impact on the metal forming quality and forming force. If the split gap is too large, the bevel gear tooth shape will not be fully filled, and if the split gap is too small, the forming force will increase. In order to obtain the appropriate outer shunt clearance value, set the outer shunt clearance as 1mm as the initial value, and gradually increase it in 2mm for numerical simulation. By observing the forming quality of bevel gear tooth profile, the best outer shunt clearance value is determined. Figures 2 and 3 show the images obtained through numerical simulation. When the split gap is 3mm, the bevel gear tooth formation quality is very good, as shown in figure 2-b. at this time, the maximum forming force is 7310kn. When the split gap is 5mm, the bevel gear tooth filling is not full enough (Figure 3-B), and the forming force is 6130kn. Select the average value of 4mm as the final value for numerical simulation again, The simulation results show that the bevel gear tooth shape filling is very full (Fig. 3-A), and the forming force is 6970kn (Fig. 2-C). Therefore, when the inner shunt gap is 5mm, the best value of the outer shunt gap is 4mm. At this time, the forming quality is good and the forming force is small.
