All-Russian Scientific and Research Institute of Tube Industry - RosNITI (Chelyabinsk, Russia):

Vydrin A. V., Dr. Eng., Prof., Deputy General Director on Scientific Work, e-mail: vydrinav@rosniti.ru
Khramkov E. V., Junior Scientific Researcher, e-mail: hramkov@rosniti.ru

Volzhsky Pipe Plant (Volzhsky, Russia):
Bunyashin M. V., Head of Central Plant Laboratory, e-mail: BunyashinMV@vtz.ru

The article provides the theoretical description of pipe wall thickness variation in the process of pipe pulling from a retained mandrel of a mandrel elongating mill by extracting sizing mill rolls. It is demonstrated that behavior of average wall thickness variation along the front pipe end during deformation between mandrel and extracting mills is similar to deformation in reducing mill. Behavior of average wall thickness variation along the tail pipe end is distinctly different because of the influence of longitudinal stress appeared during pipe pulling from a mandrel. QForm finite elements simulation presents an effect of different technological parameters on value of continuous mill mandrel coverage by deformed material. Also the article provides dependences for calculating pipe wall thickness, in particular for tail pipe end wall thickness, taking into account value of mandrel coverage. The article demonstrates obtained dependence for calculating the coefficient taking into account value of mandrel coverage depending on reduction, pass outlet zone and ratio of pipe wall thickness to pipe external diameter. The article presents dependences for calculating specified scrap value and technological parameters reducing scrap value of the tail pipe end.

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