Decreasing of guides changing with pass design optimization on continuous rolling mill using a genetic algorithm

Štore Steel Ltd. is one of the biggest flat spring steel producers in Europe. For hot rolling also continuous rolling line (10 stands) is used. The rolling plan contains more than 400 different shapes (flat, square and round bars) and dimensions which are rolled monthly. When changing from one dimension to another, the adjustment of individual stands occurs so that the desired dimension is achieved with the new setting. While changing the rolling dimensions the following could be taken into account: changing of the rolling stand, changing of guides or changing of position of corresponding guides. The aim of the study was reducing the changing of the guides (entry and exit). This aim was accomplished by changing the pass design and by simultaneously mounting of additional guides. In order to change the pass design, the genetic algorithm was used. The optimization has shown that based on existing rolling schedules of round bars the changes can be reduced in average by 36.3%.