A three-high mill of screw rolling for cobbing of the billet which enables use of continuously casted billet in tube manufacturing process, which is economically justifiable,as well as increase the steel structure quality and technological properties was installed on TPA-80 of JSC "SinTZ" . While assimilating the new process the problem of increase of defective products in the form of tube buckles has been identified, and the reason for this increase is the formation of blinks on the back end of the billet and the subsequent formation of D-rings while piercing, their break-away and getting into the deformation zone. In this article the reasons for formation of tube buckles while rolling are examined, problems of mathematical modeling of screw rolling and flashing are set and solved, and the results of full-scale experiments directed to examine this question are evaluated. Practical recommendations of solving the manufacturing problem of defective products in form of tube buckles are given.
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