Study of deformation-force parameters of rolling-off process and plugless screw rolling of pipes on three-roll mills

Abstract

The possibility of using continuously cast billets and expanding the range of seamless pipes on pipe rolling units with a screw rolling-off mill is an urgent task today. In this regard, it is necessary to resolve issues related to the study of deformation-force parameters of the process of rolling-off and plugless screw rolling, which is especially important when developing new modes of rolling pipes. In order to expand the technological capabilities of units, which use rolling and calibration three-roll mills, such as TPA-160, the method of rolling, allowing the deformation of the shell on the wall thickness and diameter (more than 5 %). Application of this method to obtain a wide range of pipes sizes and grades requires the development of rational modes of deformation, which would increase the total reduction in diameter, while maintaining a sufficient level of force parameters, to avoid the appearance of end defects, the formation of which is characteristic for screw rolling on a three-roll mill. The results of the theoretical study of deformation parameters of the reduction site of the working zone, the influence of which is enhanced by rolling with increasing reduction in diameter, are presented. The results of experimental rolling of pipes made of 09G2S steel on the TPA-160 rolling mill with a total reduction in diameter of 24 % are presented. According to the results, the behavior of the oval coefficient responsible for expansion of the reduction zone and contact surface of metal with the roll was studied. The results of experimental and industrial rolling of a wide size and grade range of pipes from continuously cast billets with a diameter of 156 and 220 mm in conditions of TPA-160 using rolling of pipes in a rolling-off mill with additional reduction in diameter up to 37 % are described. Based on the results of experimental-industrial rolling, statistical analysis and verification of the adequacy of the results of theoretical studies of deformation-force parameters of the rolling-off and plugless pipes rolling were carried out.