Provision of Required Depths of Notches on Steel Rebar by Means of Unwind Machine Electric Drive
The paper describes the results of theoretical and experimental research of the effect made by wire rebar production line electric drive parameters to the depths of notches on the rebar. It was shown that the control systems of the existing production line units did not provide the required depths of notches. The new scientific results were obtained by means of modeling the wire tension created by the line electric drives and statistical processing of the notch depths data. The following results were obtained: correlation between the unwind machine electric drive breaking torque alteration and depths of notches variation was proved; the allowable range of the wire tension variation at the inlet of profile stand was found; the method of unwind machine electric drive breaking torque efficient alteration, which was needed to stabilize wire tension at the inlet of profile stand under the wire fill-in radius variation, was developed; additional technological requirements to the line electric drives were proposed; empirical equations for unwind machine electric drive torque were obtained. After industrial approbation of the developed technical solutions there was achieved reduction in off-grade rebar percentage from 7.2 % to 1.1 % for 5 mm wire diameter and from 5.8 % to 0 % for 9.8 mm wire diameter.