Modeling the Laws that Determine the Quality of Rolled Rounds During the Rolling Operation

Abstract

It is proposed that results obtained from the experimental-theoretical solution of a three-dimensional problem on the plastic flow of metal be used to determine the main reasons for variations in the output of usable metal products. The results were obtained on the basis of models of quality. Modeling was performed to analyze a technology for rolling a broad range of structural-grade carbon-steel rounds that then undergo cold extrusion and upsetting. The rounds are rolled on a light-section mill and a rod mill at the EVRAZ ZSMK combine. It is shown that under the given production conditions the value of the integral index of rolled-product quality which characterizes the output of usable metal over long periods of time is determined mainly by simultaneous processes that involve the healing (or deepening) of surface defects, the formation of cracks on the surface of the semifinished products, nonuniform wear of the grooves of the rolling-mill passes, and depletion of the reserve ductility of the metal in the region where it comes into contact with the grooves. The results have been used to substantiate corrective measures taken in the multi-stage manufacture of rolled products at the combine. The measures were substantiated within the context of the combine’s existing quality-control system.