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View of December' 2015 Issue
Model based width control in finishing mills
By D. Kotzian, Primetals Technologies Germany GmbH , Dr. W. Tautz, Siemens AG
Reduction of width deviations and avoiding of overwidth and below-minimum widths after the finishing mill (FM) are challenges for today’s basic and process automation systems for hot strip mills. By default, the strip width in a hot strip mill is manipulated by pressing or vertical rolling of the strip in the roughing mill (RM). The width deviation after the FM arises from width deviation in front of the FM or from width spread anomaly inside the FM. The behavior of width spread in a FM depends on effects in roll bite and on the creep deformation between the stands. In this paper, we show that strip width can be manipulated by tension control in the FM. Furthermore we present a concept and test results of model based width control. Width deviations are measured in front and after the FM. The entry width deviation is compensated by a feed-forward width control (FFWC). The residual exit width deviation is compensated by a feedback width control (FBWC). Moreover, the model based FFWC considers effects of width spread in roll bite and the creep deformation between the stands.
Functional enhancements to improve the rolling process within plate and steckel mills
By M. Kurz, B. Schmidt, D. Krautwurst, Primetals Technologies Germany GmbH ,M. Clark, Primetals Technologies Limited
The vertical integration of the mechanical equipment and the process models is the key for better product quality and flexibility. Fully automatic thermo-mechanical rolling using modern physical models and intelligent sequencing strategies achieves optimum grain refinement and thus improves the mechanical properties. A novel profile and flatness strategy relies on physical modelling, enabling large reductions to be taken without risking poor flatness. In the Steckel Mill rolling process, advanced speed control has been developed to apply smooth accelerations and decelerations of the drum in order to avoid strip width variations and to lower the mechanical stress on the deflector rolls. Head and tail tapering based on the process dependent force deviation during thread-in/thread-out provides a significant reduction in the impact loads on the mechanical equipment. Throughout the rolling and cooling stages of processing, accurate calculation of the thermal state of the plate is performed by the temperature monitor. Monitoring and modelling of the material temperature along the length and through the thickness in combination with the advanced process automation of the cooling sections enables tighter control of the final plate / strip mechanical properties and the expansion of the product portfolio (X70, X80 grades). The introduction of model based roll alignment control has been proven to be a key strategy for camber-free rolling, achieving a significant increase in throughput and rolling stability. Advanced pacing strategies within the mill area and cooling bed charging optimization provide an optimized material transport throughout the entire production chain including speed optimized crop shear sequencing for the Steckel-Plate dividing process.
Demand for premium grade steel in India: opportunities for import substitution
By Dr. Vishwanathan Nagarajan, General Manager, Ferro Tech India Pvt. Ltd., Mumbai
The quantity of flat steel imported into the country since the start of year 2012 has been analysed. The article briefly discusses the various categories into which the flat steel is imported and aims to throw light on certain premium grades that could be targeted by the domestic steel mills for import substitution.
Electrolytic manganese metal production – An overview
By Ch.Sambasiva Rao, President, Anjaney Alloys Ltd., Maithan Group, Visakhapatnam, A.P
Electrolytic manganese metal production is yet to start in India and it is already successfully being produced in the countries like China and South Africa. In this paper process details are shared (both selenium free and with selenium) which is in practice and environmental issues are also highlighted including its mitigation measures. Detailed description of process at different plants of other countries is also discussed in this paper for the benefit of the readers.
New rolling method of reversing cold rolling mill
By Yohei Kannaka, Tanehiro Kikkawa / Rolling Mill Department, Technology & Engineering Division , JP Steel Plantech Co.
A reversing cold rolling mill has been suffering from such drawbacks as unrolled portions necessarily produced in head and tail ends reduce yield, and time consuming works including removing of coils, threading of the strip and holding of the strip with the tension reel, which result in decreasing productivity. There has been developed a new rolling method and facility (Zoom-MillTM, Zero-Oriented Off-gauge Minimization) that allows a leader strip and a product coil are connected using a spot welding machine and are finished through even-number passes in a reversing cold rolling mill. It is expected to reduce unrolled portions (improvement of yield) as well as improvement of productivity. The first Zoom-MillTM was put into practical use and commercial operation started in March 2010. This mill is working very well as intended initially, achieving approximately 1% improvement of product yield of the products immediately after commencement of operation.Productivity of the mill was also sharply increased along quick learning curve.
130 % stronger: igus offshore energy chains with new separators .
By Our News Bureau
igus GmbH, Cologne, has developed new e-chain separators that are extremely abrasion-resistant and are especially suitable for stiff cables and the high fill weights that are typical in the offshore industry. The holding forces of the separators are now 130 per cent greater than those of the usual locking separators of the E4.1 series. The motion plastics specialist has thus supplemented its extensive product range of safe, low-maintenance and energy-efficient systems in the offshore area, enabling customers to improve the technical performance of their systems and considerably reduce their costs.
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