Estimation of Spray Lubrication and Die Temperature for Die Wear Life Prediction in Hot Forging

We have been developing a process design CAE system to predict die wear life in the process design stage for the hot forging of steel. Our goal is to reduce production costs by shortening the development period, while maximizing the life of the die. In our system, we use an expression that defines the relationship between die wear, die strength, and friction factors, such as die pressure, sliding speed, and the coefficient of friction. To predict the die wear life with high precision, it is important to obtain the actual coefficient of friction and the heat transfer coefficient for use in a die temperature analysis that considers both heat and deformation. It is also important to clarify the effect of these friction factors on the die softening and wear. For this study, we considered the use of a hot forging die with a forging machine that is typically used for the production of connecting rods and so on. We determined the lubricant adhesion and the heat transfer coefficient variation that results from spraying lubricant, by performing a lubricant spray model test. Moreover, we devised a new hot ironing test to obtain the relationship between the coefficient of friction and the lubricant conditions, as well as the relationship between the friction factors and die temperature.