DETERMINATION OF THE FRICTION COEFFICIENT IN THE PROCESS OF HIGH-SPEED ROLLING

Abstract

The aim of this work is to determine the probable range of changes in the coefficient of friction for a stable process of high-speed rolling. The friction coefficients were determined using the modified Blend-Ford method, the empirical Ekelund dependence taking into account the influence of velocity on the Zander dependence, and the energy index of plastic friction proposed by Oginski was determined. The modification of the Bland-Ford method consisted in the refusal to provide one-zone sliding along the deformation zone, i.e., we used the data of the usual rolling process in the presence of an forward slip. Calculations were performed on the technological parameters of rolling wire rod with a diameter of 6.5 mm of medium carbon steel in the conditions of wire block 210. In particular, we used the average values of force and moment of rolling for the campaign of the set of rolls of the block. All calculated values of friction indicators on the modules of the block received less than 0.15. According to the Blend-Ford method, the values of the calculated coefficients of friction decrease almost monotonically in the direction of rolling in the range of 0.143 - 0.093. Eklund-Zander ratios ranged from 0.117 in the first pass to 0.099 in the tenth. The energy index plastic friction of Oginsky's was obtained in the range of 0.091 - 0.045. From the analysis of the obtained data it follows that the Blend-Ford method provides the closest to the real values of the coefficient of friction. The values calculated by this method correspond to the capture conditions for a steady rolling process. Other reviewed methods give the value of the coefficient of friction less than half the angle of capture. For the practical use of data obtained on the basis of actual technological parameters of rolling a specific profile size of wire rod according to the Blend-Ford method, the distribution of friction coefficient values by block modules was obtained by regression depending on speed and temperature. Thus, it is established that the coefficient of friction during high-speed rolling in wire blocks can take values less than 0.15. According to the obtained data, it is necessary to take into account the decrease in the coefficient of friction of the steady process from the first to the last module, due to the increase in speed and rolling temperature.