Online control system for EVO 2+4roll bar reducing and sizing mill of Primetals Technologies

摘要

The Bar Reducing and Sizing Technology has a core function in the value-chain for the production of rolled Special Bar Quality products. Primetals Technologies has tested industrially the 4roll ultra-sizing concept as a complement to the 2roll reducing and sizing group of stands. As a synthesis of a consolidated know-how, Primetals developed a new mechatronic unit, the EVO 2+4roll mill, based on the compact combination of a 2roll high-reduction module followed by a 4roll low-reduction module for ultra-precise sizing: it is a patented solution of Primetals and a break-through technology for superior metallurgical and technical features of the rolled product, allowing to gain significant technical and economic advantages in the hot- and post-rolling process routes. A control system for this sizing block has been newly designed. RINA Consulting Centro Sviluppo Materiali SpA supported Primetals in the development of algorithms and guidelines for the process control system implementation. The control logic is based on the definition of “sensitivities” or “system derivatives” used, in a feed forward mode, as reference for the online correction and/or regulation of the control parameters, taking into account the small perturbation of the control variables during the rolling, starting from a working point. The conditions, in terms of control variables values, related to the working and “perturbed” points are evaluated using a mill setup model. On the other hand, a feedback module has been implemented, taking into account the online measurements, so calculating the sensitivities on the base of the actual measured quantity.