Physical and computer modeling of the shape of the rear end sections of pipes

Reduction-stretching mills are used to expand the range of pipes produced and increase productivity on modern pipe rolling units. However, a characteristic feature when reducing pipes with tension is the formation of thickened ends. This phenomenon is due to the fact that the front and rear ends undergo shape change under conditions other than deformation of the middle part of the pipe. The nature of the change in the wall thickness at the ends of the pipes determines the length and weight of the end trim, which largely determines the economic performance of the entire pipe rolling unit as a whole. In this paper, the influence of rolling parameters on the length of the thickened ends is studied using physical and computer modeling of the process of reducing pipes in one cage. For a comprehensive study of the reduction process, it is necessary to take into account most factors, such as the ovality of the gauge, the level of tension, the degree of deformation, the degree of thinness, etc., other than the deformation of the middle part of the pipe. Some of these factors, for example, the influence of the intercellular back tension on the roll is better realized in physical modeling, and some factors (for example, the temperature of the workpiece) are better investigated in computer modeling. These studies will help in the development of technical solutions to reduce the length of thickened end sections of pipes. A working tool (drawing ring) was created to create a back tension in an experimental study that simulates the process of operation of a reduction-stretching mill (creating tension). To improve the mechanical characteristics, the drawing ring was subjected to heat treatment, consisting in heating for quenching in the austenitic region above the Ac3 point at a temperature of 880 °С for 20 min.