August 2019 Volume 1

FORGING RESEARCH

condition is applied to the rest of the surface. Figure 2-16 shows the meshed workpiece and configuration of boundary conditions. A step size of 0.5 second is used and the induction heading simulations lasts for 220 seconds.

Equation 1

Figure 2-16: Meshed Workpiece and BCs in the Heating Operation

In modeling of the upsetting operation, the workpiece is modeled as the rigid-plastic and the dies are modeled as rigid. Distribution of weight factors for automatic meshing are Wboundary curvature: W temperature : W strain : W strain rate : W window = 0.3: 0.2: 0.2: 0.3: 0. Remesh is done every five steps or when the interference depth exceeds 0.2 mm. Contacts between the workpiece and the die and a self-contact of the workpiece are specified by setting the shear friction factor of 0.3 and the heat transfer coefficient of 11000 w /( m 2 K ). Figure 2-17 shows the meshed workpiece and workpiece-die contacts which are in blue and green. A convection boundary condition is applied to the workpiece-environment contact area. In order to lessen heat dissipation from the workpiece to the die and environment, the forming time is limited to 6 secs. Given the forming time, velocity of the primary die is estimated by Equation 2 and turns out to be 13.86 mmsec -1 . Simulation of the upsetting operation proceeds until the

volume of the hot solid rod is adequate for the desired flange size.

where t is

the forming

time, Vol is volume of hot material Equation 2

In modeling of the flanging operation, velocity of the primary die is 60 mmsec -1 , which makes the forming time around 6 secs. The simulation stops when height of the flange is reduced to 25mm. Other settings, such as automatic meshing, remesh criteria, contacts, thermal boundary conditions, are the same as those used in the upsetting operation.

FIA MAGAZINE | August 2019 60