Résumé : A mathematical model is proposed to describe the processes of cooling and relaxation of an oriented polymer melt on a tempering surface. On the basis of this model an algorithm is established that makes it possible to calculate the temperature distribution in the melt from the given external parameters and characteristics of the material. With the aid of of this algorithm the rate of melt cooling at tempering is evaluated. The relationship between the tempering time and the degree of relaxation of macromolecules under predetermined conditions was established.