Study of the process of formation of tubes end sections during longitudinal rolling in grooves formed by a different number of rolls

The work substantiates the relevance and highlights the degree of development of the research topic. The main advantages and disadvantages of the process of rolling hollow billets with the use of modern longitudinal rolling mills with 2 and 3 roll grooves are noted. With the help of physical and computer modeling, a study of the process of longitudinal rolling of pipes using 2 and 3 roll passes was carried out, for the formation of end sections (scrap). Established and numerically reflected the relationship between the size of the reduction of passes of a continuous rolling mill with 3-roll and 2-roll stands and the length of the end sections of the pipes. It is clear that the use of 3 rolls, forming a groove, allows to reduce the total end cut by 1.5 times, in contrast to 2 rolls. It has been determined that the main technological factors influencing the formation of the end sections are the ratio of the external diameter to the wall thickness of the strip (D/S), the reduction along the wall thickness, the elongation ratio, and the number of rolls required to form the groove. An empirical formula has been obtained for calculating the length of the end trim, which makes it possible to evaluate the influence of the number of rolls in the stand, the D/S ratio and the stretch ratio.

Hollow Lateral Extrusion of Tubular Billets – Further Development of the Cold Forging Process

Light weight engineering in structural design and use of lighter materials are becoming increasingly important in bulk metal forming. Results gained by a DGF funded project which will be introduced in the following, concerning novel advancements of hollow lateral extrusion. Paper exhibits further development of this process, so cold forged components having undercuts without using a lateral tool plane easily can be manufactured. Thereby, the focus of attention is on the tool design as well as on the analysis of the unmodified forming process. Therefore, experimentally investigations have been carried out, failures on components are analyzed and process limitations of an experimental setup for cold forging of hollow billets at room temperature are illustrated.