Improving Quality in the Process of Hot Rolling of Steel Sheets

Stefan Markulik,Tomas Villinsky,Anna Nagyova,Renata Turisova

doi:10.3390/app11125451

Abstract

The hot rolling of steel sheets is a highly energy-intensive process. There are technical and operational issues associated with this process, and the causes of these issues can be various. This study involved analysis of one issue that has a great influence on the resulting surface quality of rolled sheet metal: rolled foreign material. After the sheet cools, rolled foreign material tends to fall off and a hole then remain on the surface of the sheet. This paper focuses on the search for the root causes of the occurrence of foreign material rolling. The basic categorization of the causes of this issue was performed by experienced long-term operators. The 4M method (man, machine, method, and material) was used to categorize the causes. Pairwise comparison was used to verify the result. Using energy dispersive spectroscopy analysis, the origin of the foreign material was identified. The analysis confirmed that the foreign material was not derived from the primary material. Further research showed that the cause of the issue was the guide rulers, which are a structural part of the rolling mill. Measures were taken to significantly reduce the incidence of the problem, which also had the effect of reducing financial losses, which fell by a third in 18 weeks. In the future, it will be necessary to make design changes (modernization of the rolling mill), which will, however, require more financial investment.

Highlights

The automotive industry is currently one of the largest processors of rolled sheets
The aim of this paper is to increase the quality of the process of hot rolling of steel sheets with a focus on reducing various defects, which will subsequently be reflected in reduced product quality, or in the form of increased costs associated with the process
The aim was to determine the weights of the criteria–causes listed in Table 1 by means of pairwise comparison

Summary

Introduction

The automotive industry is currently one of the largest processors of rolled sheets. In the industrial production sector, the demand for a wider range of products in everincreasing quantities is constantly growing. The production of steel must be based on predetermined properties required by the customer to meet demanding specifications [2]. [5] focused on an approach for rolling techniques in a metal forming operation as part of an industrial production process. The proposal of hot rolling as a method of metal forming was published in [7]. The aim of this paper is to increase the quality of the process of hot rolling of steel sheets with a focus on reducing various defects, which will subsequently be reflected in reduced product quality, or in the form of increased costs associated with the process

Objectives

Methods

Results

Conclusion