Lipetsk State Technical University (Lipetsk, Ruissia):

S. M. Belskiy, Dr. Eng., Prof., Dept. of Metal Processing, e-mail: belsky-55@yandex.ru
I. I. Shopin, Cand Eng., Dept. of Metal Processing

At the later stages of processing steel flat products, due to the instability of the qualitative characteristics of the rolled products, a number of losses are formed, which are unknown at the early stages. In this regard, feedback from the later stages of processing to the early stages plays an important role in long production chains of flat rolled steel. Feedback, as a rule, includes toughening the requirements for the quality characteristics of the hot rolled strip or its processing parameters. In turn, toughening requirements leads to an increase in production costs in the early stages of processing. Therefore, in the framework of the formation of optimal requirements for hot-rolling strip within the framework of a single production chain, mathematical modeling plays an important role. This allows you to quantify the amount of loss reduction at the last stages of processing due to the tightening of requirements for strips. Which, ultimately, allows you to make an economically balanced decision on the implementation of the proposed costly improvement measures. In the framework of this work, we consider the process of forming requirements for hot-rolled steel to reduce strip breakage during cold rolling using the method of mathematical modeling. Strip breakage during cold rolling leads to signifi cant losses in a continuous mill: downtime associated with the elimination of consequences; additional consumption of metal, work and backup rolls. Strip breakage is a relatively rare event that has a complex genesis with many root causes. For root causes search and elimination the analysis should rely not only on expert opinion, but also on statistical tools. The strip breakage occurs at a particular strip location, which further complicates the identification and analysis of its root causes, since a critical deviation of the parameters in only one small section of the strip may already be the cause of the subsequent breakage during cold rolling. In this work, first, methods for testing hypotheses and regression modeling are used to identify the key parameters of hot-rolled strips that affect the strip breakage. Then, on the basis of the developed mathematical models, threshold values for key parameters are determined, exceeding which increases the probability of strip breakage.

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