Forming Simulation and Experiment for Progressive Fabrication Process of Inner Fin in Heat Exchanger

Abstract

In this study, a progressive process was performed to fabricate the inner fin of a high-efficiency heat exchanger. A forming simulation was also carried out on the concavo-convex of the inner fin, forming a simulation based on elastic-plastic finite element method. The forming analysis where the speed of the press descended and ascended was set to five seconds showed that the effective stress was at a maximum of about 69 MPa in the curved portion where the bending occurred. Therefore, the die was designed based on the simulation results, and the inner fin die was installed on the 400-ton capacity press. After that, the inner fin fabrication experiment was conducted under the same condition as the simulation. Crack was not found from the curved portion of the concavo-convex of the inner fin. The profile of the concavo-convex of the prepared inner fin measured 6.7~6.8 mm in depth, 2.65~2.7 mm in width, and 0.3 mm in thickness.

Fig. 1 Inner fin of heat exchanger

Fig. 2 Mesh generation of blank and die

Fig. 3 Boundary condition between die and blank

Fig. 4 Fabrication process of inner fin

Fig. 5 Core die of inner fin

Fig. 6 Measurement of inner fin

Fig. 7 Forming steps of simulation results

Fig. 8 Forming load curve vs time

Fig. 9 Fabricated 20 inner fins

Table 1. Results of fabrication about 5 seconds of press speed

Table 2. Height and width of concavo-convex

Table 3. Flatness of inner fin