Estimation of the Heat Transfer Conditions in a die Radius during Hot Stamping

• Published in: Key engineering materials 2013-06, Vol.554-557, p.1509-1516
• Main Authors: Blaise, Alexandre, Dessain, Christine, Bourouga, Brahim, Abdulhay, B.
• Format: Article
• Language: English
• Subjects: Blanks; Contact; Estimates; Heat transfer; Mathematical analysis; Mathematical models; Temperature distribution; Thermocouples
• ISSN: 1013-9826; 1662-9795; 1662-9795
• DOI: 10.4028/www.scientific.net/KEM.554-557.1509

Established process in the automotive industry, the hot stamping process consists in heating a blank until complete austenitization in a furnace before transferring it to a press where it is formed at high temperature before being quenched by contact with the cold tools. During the forming step the hot blank slides on the die radius. Locally, the contact pressure can reach very high values. Due to this contact, heat transfer between the hot blank and the die can be significant. Using an omega die instrumented with eight thermocouples localized in the die radius, a 2D inverse method is used to estimate the heat flux that crosses the Blank/Die interface and the temperature field in the die radius and on the die surface. Four thermocouples are located in the blank thickness and a FE analysis is performed to estimate their positions as function of the time. The temperature in the thickness of the blank is considered as uniform according to Biot number value. This assumption is checked afterward. Thus, it is possible to estimate the sliding thermal contact resistance between the blank and the die as a function of time in front of each thermocouple of the blank. The estimation of the temperature field in the die can be useful for investigating the fatigue that occurs in the die. On the other hand, the knowledge of the interface condition in the die radius can present a high interest for improving the numerical simulations of this process.