INFLUENCE OF THE LUBRICANT ON TEMPERATURE DISTRIBUTION IN THE FORGINGDIES

Experimental and theoretical analysis of the influence of the lubrican t on the temperature distribution in the tool during forging is presen ted. Finite element solution of the general diffusion equation is used to calculate the heat transfer contact between the die and the hot wo rkpiece and during the interpass times. The results of calculations ar e compared with the results of measurements carried out using thermoco uples inserted in the die. Two ways of modelling heat transfer through the contact surface are considered. The first treats a lubricant as a separate layer with the relevant thermal properties. The second assum es a temperature discontinuity at the interface and introduces the hea t transfer coefficient. insulating properties of various lubricants ar e compared. White-water lubricant shows the best insulating properties . The values of the heat transfer coefficient obtained from the invers e analysis vary from 2600 (without lubrication) to 1500 W/m(2)K (white lubricant).