August
2006
Upgrade of the Mechanical Drive Equipment in the Roughing Mills at California Steel’s Hot Strip Mill
Yuichiro Shinohara (left), assistant to the executive vice president — operations, and Gary L. Bowman (center), retired, California Steel Industries Inc., Fontana, Calif. (yshinohara@californiasteel.com, bowman74@earthlink.net); and Kuniyoshi Sugimoto (right), executive adviser, Hasegawa Gear Works Ltd., Tokyo, Japan (k_sugimoto@haseg.co.jp)
Upgrades at CSI’s hot strip mill involved new U-joint spindles, new spindle supports, and new Symmarc gear for the pinion stands on R3, R4 and R5. This article describes both the improvements and results.
Ridge-buckle Defect in
Thin-rolled Steel Strip
Wanda M. Melfo (left) and Rian J. Dippenaar (center), University of Wollongong, New South Wales, Australia (wm01@uow.edu.au, rian@uow.edu.au); and Christopher D. Carter (right), BlueScope Steel Ltd., New South Wales, Australia (chris.carter@bluescopesteel.com)
A project was created to implement mathematical modeling techniques, laboratory experiments and
in-plant trials in order to understand the causes of ridge-buckle defects. This article details the approach taken and the results of the in-plant trials.
Audits of Existing Hydromechanical Descaling Systems in Hot Rolling Mills as a Method to Enhance
Product Quality
Jürgen W. Frick, director — international metallurgical division, Lechler GmbH, Metzingen, Germany (frju@lechler.de)
A descaling system audit is used to determine how existing conditions affect the surface quality of steel strip. Examples of actual system audits are given, along with proposals and process results. Also
discussed is how the design of a descaling system can be optimized.
Design Criteria for Descaling at Dofasco’s No. 2 Hot Mill
Brian D. Nelson (left), research manager — flat rolling, and Ghassan Gebara (center), improvement technology coach, Dofasco Inc., Hamilton, Ont., Canada (brian_nelson@dofasco.ca, ghassan_gebara@dofasco.ca); and John Tiley (right), consultant — iron and steel, Hatch, Mississauga, Ont., Canada (jtiley@hatch.ca)
This article outlines the mechanical design calculations and features of a modern high-pressure descaler to effectively remove the types of scale that grow during hot rolling processing. Specific events and design issues at Dofasco are presented.
Crop Optimization — Beyond the Obvious
Terrance Dozier, automation engineer, United States Steel Corp., Fairfield Works, Fairfield, Ala. (tdozier@uss.com)
In an effort to optimize U. S. Steel’s Fairfield Works hot strip mill, several items were identified as primary contributors to yield loss, especially the crop shear system. This article examines the considerations made during the installation and commissioning of the ACCUCROP system.
Three-dimensional Imaging-based Slab Width Measurement
Frank (Fuu-Ren) Tsai (left), senior engineer, Tony (Chang-Hung) Lin (center), engineer, and Tzyy-Shuh Chang (right), chief technical officer, OG Technologies Inc., Ann Arbor, Mich. (tsai@ogtechnologies.com, lin@ogtechnologies.com, chang@ogtechnologies.com)
A dual-laser, self-alignment monitoring width gauge system was developed to measure slabs while they are moving and to detect the contour of the slab side surface. This article reports test results of the width gauge after one year of operation.
Numerical Simulation of the Rate of Dross Formation in Continuous Galvanizing Baths
Frank Ajersch, professor, École Polytechnique de Montréal, Montréal, Que., Canada (frank.ajersch@polymtl.ca); Florin Ilinca and Jean-François Hétu, research officers, Industrial Materials Institute (IMI), National Research Council, Boucherville, Que., Canada (florin.ilinca@cnrc-nrc.gc.ca, jean-francois.hetu@cnrc-nrc.gc.ca); and Frank E. Goodwin (pictured), executive vice president, International Lead Zinc Research Organization (ILZRO), Research Triangle Park, N.C. (fgoodwin@ilzro.org)
The rate of dross formation for 19 different conditions was calculated for a two-hour cycle. Differences in the evolution of the amount of dross formed in the galvanizing bath over this period were analyzed. The results can be used to provide guidelines for bath operation to minimize dross formation and accumulation.
The Interaction of Liquid Iron With Oxides and Its Effect on Solidification and Heat Transfer
P. Nolli, Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pa. (paolon@andrew.cmu.edu), and A.W. Cramb, dean of engineering, Rensselaer Polytechnic Institute, Troy, N.Y. (cramb@rpi.edu)
In the last few years, many companies have announced the final stage of the commercial development of strip casting of steels. In strip casting, heat extraction and productivity are limited by the thermal resistance at the interface between processed material and the moving mold (rolls for twin-roll strip casters). From an industrial point view, in order to increase productivity, methods to improve interfacial heat transfer rates must be found. Among the many factors influencing interfacial heat transfer, films of various compositions, either formed during casting or deposited before casting on the surface of the rolls, can have a significant effect on the achieved heat transfer rate. The objective of this study was to assess the feasibility of improving the heat transfer rates, during solidification of metal samples in direct contact with a copper mold, by the application of thin coatings on the mold surface itself. To address this issue, solidification experiments were performed with the mold surface either uncoated or coated with coatings of different compositions. It was observed that, after the application of certain coatings, the resulting interfacial heat flux was improved with respect to the bare copper surface.
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