The short shaft forgings produced by the company are intermediate shafts with a total length of 1120 mm and a large flange diameter of 1830 mm. Dimensions of short shaft forging are shown in Figure 1. The large flange diameter to rod diameter ratio of this short shaft forging is 2.3, which is the largest flange diameter to rod diameter ratio of the company's current production. The weight of the short shaft forging is 11 t, and the size of the maximum upsetting section of the ingot cannot meet the size of the large flange diameter. In order to increase the diameter of the ingot after upsetting, it is considered to increase the weight of the ingot by using two-piece forging. However, through calculation, it is found that the forging ratio of flange using two consecutive forging and one upsetting process can not meet the technical requirements, and two upsetting and two drawing are needed. In addition, because the forging section is too large to meet the minimum mark length after upsetting, the bottom of the drawing is prone to concave shape, and the riser end is easy to wrap the pliers, resulting in production difficulties and high scrap rate. A forging method suitable for producing short shaft forgings is developed by using the front and back upsetting flanges and rods.
1. Forging difficulties
The product has high testing requirements, and the forging ratio of large flanges is ≥2.5. The flange diameter is large, and the section size of the ingot after upsetting cannot meet the requirements of the flange diameter. The second step can not meet the diameter requirement of the small flange after using the cutting material as the step blank. It is easy to make the two flanges eccentric when the front and back parts are upset twice. When upsetting the rod part on the back side, the deformation is small, resulting in the diameter of step 2 is too small.
2. Solutions
In order to ensure the forging ratio of the large flange and make the forging flange compacted and pressed through, the large flange is formed by local upsetting. In order to prevent flange leakage during local upsetting, the total length of the step 2 and the clamp should be equal to the height of the leakage disk used, and the eccentricity of the large flange and step 2 should be prevented during upsetting.
The leakage disc used in the upsetting of the large flange must have a rounded corner of R50mm~ R80mm to avoid folding at the position where the step two contacts the large flange when the reverse upsetting is made. After the large flange is formed, the forgings are placed in reverse, so that the large flange contacts the ground, the leakage disk is placed on the clamp, and the step is upset. When upsetting, it should be noted that the pliers and the big flange and the step two should not be eccentric, and the transition part of the pliers and the step two should be uniform, otherwise it is easy to appear eccentric between the step two and the big flange during the upsetting process on the back.
At the same time, the height of the leak disk placed on the clamp should be greater than the sum of the length of the clamp and the amount of pressure when the step is upset. The diameter of step 2 is up to 300mm smaller than the forming size when the material is cut, this is because the pressure is small when the reverse upsetting is small, the deformation is small, if the diameter of step 2 is too small, it is not easy to upset to the ideal size range.
3. Conclusion
The upsetting method is suitable for producing any kind of short shaft forging, which solves the production problem of short length and large flange diameter of short shaft forging. In addition, even if the product does not have a suitable tool to use, the method can be used to upset the rod diameter, without the need to manufacture special tools, reducing the production cost of the enterprise.
