QUALITY ENHANCEMENT THROUGH MODERN GAUGE AND SPEED CONTROL FOR THE TANDEM MILL OF EKO-STAHL GMBH

Objective. Within the scope of a two-stage refurbishment programme, Ek o Stahl GmbH has modernised a four-stand tandem mill of Russan design, built in 1968, in order to meet the increasing requirements with rega rd to productivity, product quality and flexibility. In the first stag e of the refurbishment the entry section, the hydraulic screwdown syst em and the process control and instrumentation equipment were replaced . In the second stage, primarily the gauge and speed control system wa s modernised in 1996 by ABB Industrietechnik. Summary. The tandem mill supplies a broad spectrum of products ranging from mild, unalloyed st eels and structural steels through to deep-drawing steels for the auto motive industry. Following the completion of the second refurbishment stage the mill now has a modern automation and control level which per mits outstanding strip quality and a high availability of the plant an d equipment. The demand for low capital outlay costs and short retrofi t times was met by retaining the existing Ward-Leonard converters and roll drive motors. The required dynamic response of the drives is achi eved by means of modern power converters for the field excitation, fea turing adaptive generator magnetic flux control. It was possible to de monstrate the suitability of this solution as early as the tendering s tage by means of mathematical simulations. The gauge and speed control equipment has been fully integrated into the existing automation syst em. An expressive diagnostics system has also been installed. (E 29732 ).