ANALYSIS OF DIMENSIONAL PARAMETERS OF ROLLS OF LONG PRODUCTS MILLS

Abstract

For long products rolling mills, which in most cases have a significant number of sequentially located working stands, the tasks of choosing the optimal materials, structures and roll sizes are quite relevant. The dimensional parameters of the rolls, which are chosen at the stage of design of the mills, largely determine the efficiency of the technological process. Therefore, the tasks of substantiating the choice of roll sizes for long products rolling mills are relevant and have important practical significance.
 The purpose of the work is to analyze the dimensional parameters of rolls of modern long products rolling mills, to identify the characteristic features of size ratios and to develop recommendations for choosing the main sizes according to the most significant criteria.
 An analysis of the dimensional parameters of rolls of typical modern mills of long products of several leading manufacturers was performed. It was established that the actual ratios of the sizes of the main elements of the rolls only partially correspond to those given in the technical and educational literature.
 The ratio of the nominal diameter of the rolls to the initial rolling thickness varies from 3.75 to 38.5. These values indicate that over the past few decades, the range of changes in this indicator has shifted towards smaller values.
 For the ratio of the length of the barrel to the nominal diameter of the rolls, the most common range of values is from 0.93 to 2.56. That is, there is a decrease in the lower limit of this range for stands of housing and housingless type. The use of rolls with approximately the same barrel length and diameter is due to the characteristics of roll materials and the desire to reduce operating costs by simplifying equipment designs.
 The ratio of the diameters of the necks and the barrel of the rolls varies from 0.40 to 0.57. Such values indicate significant progress, both in the use of new rolls materials and in the improvement of modern bearing assemblies and stands.
 Recommendations have been developed for the selection of the main sizes of rolls by groups of stands of long products rolling mills. From the calculations of the admissible rolling force according to the conditions of the strength of the necks of the rolls, it is proved that according to the criteria of strength and wear resistance, the minimum diameter of the rolls of finishing stands is 350 mm.
 The limits of changes in the dimensional parameters of the rolls determined from the analysis and the recommendations for choosing such dimensions can be used in the design of new rolling mills.