EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

**First successful flying roll change installation for increased production yield** Pushing the horizon of stainless steel continuous cold rolling mill performance on the edge of perfect strip quality level, not compromising with the highest yield and productivity ratios, has been given a new milestone by Primetals Technologies. After a first reference of X-HI® technology tandem mill on the Direct Rolling Annealing and Pickling Line (DRAPL) of Baosteel Desheng, Primetals Technologies installed a later reference at Beihai Chengde on a Continuous Tandem Cold Mill (CTCM). X-HI® technology has been especially designed to allow flexible and fully continuous rolling operation on 18-Hi mill type, with specific patents applied for endless rolling capability. Amongst differentiating features of X-HI® technology, the specific design and control of rolls position and efforts are giving the stability and precision required for ultimately extending the current rolling capabilities of such continuous stainless rolling mills. This last commissioned reference is a continuous 5 stand tandem mill, equipped with mill entry and exit strip loopers allowing for no-stop rolling operation. This configuration increases significantly the mill yield ratio by limiting out-of-tolerance strip thickness and the productivity as well, thanks to endless continuous rolling operation. The concept draws innovative approach to allow fully automatic roll change operation with the strip passing through the said mill stand. As ultimate benefit for saving several minutes of production and eliminating off-gauge material, work roll change can be done on the fly without stopping the strip rolling process: while the roll gap is open, the thickness reduction at that stand is taken over by another actively rolling stand. Typical case shows work roll change operation achieved up to 120 m/min rolling speed. This operation can be done for all the rolls: WR, IMR and SSR, excepted BUR. This mode of operation is a world premiere and opens the field of new gains in the world of stainless steel and very high strength steel grades.