Triumphant news has been pouring in from the 1580 hot rolling production line of Shougang Jingtang United Iron & Steel Co., Ltd. that new breakthroughs were recently made in the production of limit-specification products, and the stable rolling of ultra-thin 1.2 mm products has been realized after the stable rolling of 1.49 mm products in November, 2016, thus providing strong support for further expanding the market of hot-rolled products.

The 1580 hot rolling production line is an important production line for hot-rolled steel strip products, as well as a production line of unique process characteristics, with an overall length of 550m of the main rolling line and a designed annual hot-rolled steel coil output of 3.9 million tons. Its types of steel mainly include high-quality carbon structural steel, low alloy structural steel, weathering resistant steel, low carbon aluminum-killed steel and ultra-low carbon steel, and the leading products are containers and tinplate. The hot rolling division of Shougang Jingtang has thoroughly implemented such job requirements as readjusting the product mix and upgrading product quality, given full play to the advantages of this production line in the rolling of thin products, and constantly developed new product specifications, especially limit-specification products that are more suitable for the current market demand, thereby providing strong support for Shougang Jingtang to gain the market of hot-rolled products and improve the market benefit-making capability of its products.

Scientific organization. Since the beginning of 2017, the hot rolling division of Shougang Jingtang has earnestly implemented the ‘two sessions’ spirits of the Shougang Group and striven to make technological breakthroughs for limit-specification products with good market prospects. In order to ensure the stable rolling of ultra-thin products, the hot rolling division took the initiative with one mind and one heart without hesitation or dependence, cooperated closely with the production organization division and manufacturing department, proceeded with such aspects as production organization and management, production emergency response plan and equipment running guarantee, formed four groups to tackle technical problems involving production, process, equipment and operation, and held demonstration meetings many times to research and work out process programs. The technical staff have made field visits to the site to collect related technical data, then conducted careful summary and analysis, improved the production decision for reduction, detailed the ‘regulatory measures and emergency response plan’, technically improved and optimized certain problems exposed in the early production of thin products so as to ensure the stability of the rolling line, enhanced the examination and verification of the operational plan, as well as the effective control and cohesion of all processes, and promoted the management and control of orderly production so as to provide a guarantee for the successful rolling of ultra-thin products.

Process optimization. In the production process of thin products, technologists and production operators have strengthened their cooperation, conducted in-depth research into the rolling experience of thin products, analyzed the technical data through many production rolling simulations, determined such key process systems as the slab heating system, rolling process, roll-arranging finish rolling and use of process water, and made successful breakthroughs in such difficulties in process elements as temperature control and model specification, thus providing strong technical support for the stable rolling of thin products. They also closely tracked the temperature of important process control points, and adjusted the steel reheating model of the slabs so as to accurately control the tapping temperature and ensure the tapping temperature uniformity of slabs. The staff made careful operations in the rolling of thin products, and progressively conducted reduction rolling on the premise of stable rolling. In the rolling process of thin products, it is difficult to control the thin strip discharge rate of the rolling mill. In order to solve this problem, they started with the rolling models of each part, made breakthroughs link by link, successively optimized the roller configuration of the finishing mill, load distribution of the rolling mill and input of process water, gradually identified the rules for controlling the shapes of thin strips and used them in practice. In the meantime, the level-two model engineers also optimized such parameters as the short stroke of vertical roll head and the position of the rolling force, and actively communicated with the former process, thereby ensuring the tapping temperature and stability of the rolling rate.

Accurate control. In order to ensure that the working conditions and functional precision met the requirements for the rolling of thin products, the hot rolling division gave full play to the advantages of the equipment tackling group, and the technologists made full use of the maintenance time to measure such indicators as the functional precision of the equipment and the rigidity of the rolling mill. Aside from carrying out the full equipment guarantee mechanism, the equipment professionals also strengthened the inspection of equipment points where malfunctions are more likely to occur, and dealt with the problems put forward by process professionals on the functional precision of the equipment in a timely manner, so as to ensure the high-quality running of the equipment. As the first persons responsible for equipment utilization, the production operators played an active part in strengthening the board check of the billet passageway so as to ensure timely feedback and treatment as soon as hidden dangers are found in the equipment. In order to improve the operation level of the staff, a virtual technology research team was formed made up of backbones of production to carry out special training for all the operators on the production line. The stability of finish rolling proves to be the most difficult link to control in the rolling process of thin products, but the finish rolling operators faced the difficulty by actively undertaking the reduction tasks. They also actively explored the set value of the rolling mill for reduction rollers, regulated the rolling mill to good conditions so as to avoid ‘the thinner, the faster’ phenomenon of the rolling of steel strips, made full preparations with superior operation techniques and took careful steps to ensure that such key indicators as plate cut, thickness and temperature accurately hit the targets.

On February 6^th, the 1580 hot rolling production line of Shougang Jingtang successfully realized the stable rolling of 1.2 mm ultra-thin strip steel, making another breakthrough in the limits of hot rolling specifications and improving the market competitiveness of the Shougang Group’s products.