Abstract:

A new simulation method which can couple heat transfer happened in hot stamping is proposed. The interfacial heat transfer coefficient is inverse estimated by finite element method(FEM) and optimization method which make the temperature standard deviation between simulation and cylindrical experiment reach the minimum. Then the interfacial heat transfer coefficient(IHTC) is used in a hot stamping U-HAT model to obtain the heat flux data of all nodes on the tool work surface. Statistical analysis system(SAS) program is coded to process the heat flux data and calculate the time-averaged heat flux of each node. The time-averaged heat flux of all nodes corresponding with space coordinates are introduced as Neumann condition in quenching simulation performed by STAR-CCM+. The tool temperature, channel wall temperature and nonhomogeneous film heat transfer coefficient(FHTC) form steady-state quenching simulation are mapped into the hot stamping model by ABAQUS. At the moment, the IHTC and FHTC have been coupled into the steady-state hot stamping model which not only considers the heat transfer between hot blank and cold tool but also combines the heat transfer between tool and cooling water. A U-HAT tool adopted in the simulation is designed and manufactured to perform a continuous hot stamping experiment, and the steady temperatures of several specific points on the blank and tool are collected to compare with the results from simulation. The results indicate that comparing the temperature distribution of tool and blank before coupling, the value of temperature is nearly doubled after coupling and the temperature profile is migrated along inlet to outlet. Moreover, all relative errors of steady temperature at specific points between experiment and simulation are less than 10%.

Key words: coupling, temperature field, time-averaged heat flux, hot stamping