Cold rollingBig river steel
The pickling line/tandem cold mill is designed to process up to 900,000 tons of steel strip per year with strip widths ranging from 914 to 1,880 millimeters. It is equipped with an X-Pro® laser welder, a scale breaker, a turbulence pickling section and tandem cold mill. A large portion of the production volume, cold strip being 0.27 to 1.4 millimeters thick, is processed within the plant. Another component is the DUMA-BANDZINK oiling machine installed in the mill to produce pickled- andoiled material. Strip thicknesses here are between 1.4 and 5.0 millimeters. First strips were processed on the line in the summer of 2017. Thanks to the X-Pro® laser welder it is possible to precisely and quickly join difficult-to-weld, high-alloy strips, to lead them through the process reliably and roll them without any problems.
This ensures the line can handle even high-carbon or high-silicon grades. The turbulence pickling section comprises three plastic tanks of 27 meters length, each provided with its own cycle. The system is characterized by high pickling performance, low energy and acid consumption as well as low maintenance and operating costs paired with a long service life. To achieve optimum pickling results at minimum energy input, operators can actively influence and perfectly adjust all essential parameters.
The tandem cold mill processes an extremely wide range of materials, with each grade posing different, challenging requirements, and comes with five four-high mill stands. Measuring systems, control strategies and actuators make sure the high demands on strip quality are satisfied. One of these solutions is the X-Shape flatness measuring roll standing out due to its robustness and closed roll surface, to precise flatness measurement and reliable optical and wear-free signal transmission. Proven actuators such as CVC®plus technology, positive and negative work roll bending, highly dynamic hydraulic adjustment and multi-zone cooling in the last mill stand ensure top strip flatness and thickness tolerances. This mill stand technology meets the extremely high quality requirements of the automotive industry while operating at low cost. Two tension reels are installed in the exit section for continuous coiling of the rolled strips. Belt wrappers support the gentle start of the coiling action to protect the valuable finished strip. Moreover, the cold tandem mill is equipped with Rotary Inspect, the latest inline strip inspection line permitting reliable, immediate and ergonomically optimized evaluation of the strip surface quality.
One of the components that makes the tandem cold mill particularly user-friendly and contributes to reducing nonproductive times is the fully automatic roll change system with integrated automatic coupling system for all media. When it comes to environmental compatibility and maintenance friendliness, the tandem mill sets new standards, too. Cutting-edge oil-air lubrication of the bearings throughout all rolling levels reduces the consumption of lubricants, and axial bearings at all levels maximize the service life of the roll bearing assemblies. The tandem cold mill is equipped with the latest-generation fume exhaust system which responds at an early stage and reduces fume generation by optimized air flow conditions. In addition, it meets the extremely strict U.S. requirements on exhaust-air particle emissions and, just like all media and auxiliary systems, is very energy–efficient. This is accomplished, for example, by using speed-controlled pumps for precise and hence money-saving media supply.