Numerical investigation on cooling performance of hot stamping tool with various channel designs

Abstract

This paper investigates the cooling performance of hot stamping tool with various cooling channel designs, i.e., straight hole, longitudinal CCC (conformal cooling channel), transversal CCC, parallel CCC, serpentine CCC. The cooling channels are placed inside the hot stamping tool for dissipating heat during stamping process. Turbulent flow of a Newtonian fluid in a circular cross-sectional channel is analyzed by a three-dimensional computational fluid dynamic approach. Four Reynolds numbers and four outlet pressures are researched through full factorial design to evaluate the effect on the performance of various cooling channel designs. Disparate priority of each design at different boundaries is discussed in the light of numerical results. Evaluation indicators such as maximum temperature, average temperature, temperature uniformity, velocity and pressure drop are used to assess the cooling performance. Meanwhile, figures of merit, i.e., heat dissipated per unit pumping power, is also compared for five channel designs. Moreover, the reliability of this research method is verified by means of mesh independence analysis and single cooling pipe experiment. It is concluded that serpentine CCC is better than other designs at low Reynolds number, while longitudinal CCC is the best design at high Reynolds number. Besides, with the increase of mass flow rate, the maximum temperature and average temperature tend to decrease, but the temperature uniformity, pressure drop and maximum velocity tend to increase. The cooling performance mainly depends on mass flow rate and channel shape, but not outlet pressure. However, the pressure inside the channels is determined by the outlet pressure. It is also calculated that longitudinal CCC has the highest FoM (figure of merit) which represents the best cooling performance. Furthermore, it is proved that the relative error of simulation and experiment results can be controlled within 10% by mesh independence analysis and single cooling pipe experiment.