August 2019 Volume 1

FORGING RESEARCH

2.5. Application of the Differential heating based Forming Process to Shafts with Various Inner Diameters Inner diameter of the hollow shaft is a critical dimension which not only affects the weight reduction, but also dictates the mechanical performance, such as stiffness and toughness. Therefore, the relationship between weight reduction and the inner diameter is examined. Moreover, formability and feasibility of the process is investigated when it is applied to shafts with various inner diameters. Table 2-1 shows weight reduction of hollow axle shafts manufactured for various inner diameters. Weight reduction is expressed as 1− , where Vol hollow is volume of the hollow

shaft, Vol solid is volume of the solid shaft which has the same outside dimensions as the hollow shaft. The weight reduction for ID = 30 mm and OD = 50 mm is computed as 19.4%. As is shown in Figure 2-19, Figure 2-20 and Figure 2-21, the maximum effective strain increases as the inner diameter increases. A maximum strain of 7.15 is observed for the axle shaft forged from a blank tube with ID = 30 mm. The forming load in the upsetting operation decreases as the inner diameter increases. The forming load for the flanging operation shows a different trend, as shown in Table 2-2. A maximum forging load of 783 tons was obtained in the simulations. Although the load is high, it is within the capabilities of forging presses used in the industry.

Vol hollow Vol solid

Table 2-1: Dimensions of the Initial Tube and Weight Reduction for Different IDs

Length of the Initial Tube (mm)

OD of the Initial Tube (mm)

Weight Reduction

ID=20 mm ID=25 mm ID=30 mm

942 996

50 50 50

8.49% 13.36%

1083

19.4%

Figure 2-19: Maximum strain when ID=20mm

Figure 2-20. Maximum strain when ID=25mm

FIA MAGAZINE | August 2019 62