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

From the observation of the factors affecting the forging difficulty of spiral bevel gear small wheel, the volume of spiral bevel gear forging has a great influence on the precision forging difficulty. From the comparison diagram of blank and forging model, it is mainly because the die cavity extrudes the material at the tooth groove of blank to other parts, resulting in great deformation resistance in the process. During precision forging of spiral bevel gear, only the material distribution at the tooth groove of cavity and blank is different, Therefore, the flow volume of the material is approximately equal to or related to the size of the cogging volume. Therefore, it is speculated that the size of the cogging volume should have a linear relationship with the loading force. Considering that other parts of the spiral bevel gear also have influence in the modeling process, the shape of the blank and the mold cavity should be the same as far as possible in the modeling process, and the difference is only in the cogging part, as shown in Fig. 1 and Fig. 2.

Due to the similar design of blank and gear model, they are only different at the tooth slot. Therefore, theoretically, the blank is gradually extruded into the shape of spiral bevel gear, and in this process, it is equivalent to the extrusion of the tooth slot, and its volume represents the flow momentum of the material. With the gradual forming of the tooth, the contact surface between the cavity and the blank gradually increases, the tangential flow space of the blank gradually decreases, and the extrusion is difficult, so the loading force gradually increases. Therefore, the tooth groove is the main action area of the forging loading force of spiral bevel gear, so it is predicted that the loading force will increase with the increase of the tooth groove volume.

The influence of tooth groove volume on the forging difficulty of spiral bevel gear can also be compared and analyzed. The relationship between the large tooth groove volume and load of spiral bevel gear is shown in Fig. 3 and the small wheel is shown in Fig. 4. From the figure, it can be seen that the magnitude of loading force is basically proportional to the tooth groove volume, which verifies the prediction results.

There are points with large deviation trend in Figure 3. According to the analysis, it may be caused by large error in calculation. A larger amount of data can be used for more accurate analysis and multiple groups of repeated tests.

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