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Title

REVAMPING OF SKIN PASS SECTION FOR AUTOMOTIVE PRODUCTS

Authorship

PEERS, Johan; DUMORTIER, François

PEERS, Johan

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DUMORTIER, François

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DOI

10.5151/9785-9785-32335

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Abstract

Due to the increasingly stringent requirements and the needs of the automotive industry, galvanizing lines dedicated to automotive products have to be modernized and improved. Beginning of 2017, SEGAL, a Tata Steel CGL line located in BELGIUM and fully dedicated to automotive market, placed an order to CMI in order to increase the line capacity from 550kt/year to 600kt/year, to be able to process a wider range of steel grades and to improve the product quality according to automotive requirements. To achieve such a production, it was necessary to increase the loopers capacities, and to install a new inductor at the furnace, a new water quench and one BLOWSTAB® cooling box to increase the cooling capacity. To improve the product quality, a major revamping of the skin pass was necessary. The objectives were first to increase the work roll diameter from Φ560mm to Φ650mm in order to be able to transfer the required roughness with low elongation on soft material and second to increase the rolling force and tension to reach higher elongation on high strength steels. Existing mechanical elongation system has also been replaced by a completely new single AC motor with helical gearbox at each bridle roll. The request of the customer was very challenging regarding engineering, delivery time and shutdown time. Complete analysis and engineering has been done within three months with maximization of existing equipment reuse on a skin pass originally not supplied by CMI and with only paper drawings available. The complete motorization concept has been replaced, including modification of the rolls during the shutdown. For the skin pass mill, only the housing, auxiliaries inside the cellar and interconnecting piping have been kept. Indeed new roll force cylinders with increased diameter and tailor made design, new work roll chocks and new bending blocks have been supplied. All other mechanical subassemblies have be modified in order to avoid any interference with the increases 650mm work rolls, including among others work roll and back-up roll change, modification of work and back up rolls chocks and new anti-crimping. In order to limit costs and shutdown time, the modification of the housings has been avoided thanks to a smart engineering. CMI achieved such complicated revamping in a very short time since the shutdown started only 6 month after the contract signature. Moreover, the shutdown down schedule has been optimized with pre-erection works and the teams working 24/7 to implement all the changes. The complete skin pass section, as well as the other parts of this project (furnace, loopers) have been adapted during the only three weeks shutdown. Today the customer can use both 560mm and 650mm work roll diameters. Thanks to the use of the new 650mm work roll diameter, the customer is able to make the same elongation using a bigger roll force (average 20% more), which has strongly improved the roughness transfer to the strip and the removal of the defects. Today, Tata Steel SEGAL is really satisfied able to produce and supply higher quality automotive products to his demanding customers. CMI takes the opportunity of this paper to warmly thank SEGAL team for his thrust and his authorization to present and publish this paper in several conferences.

Keywords

Skin pass mill, Cold rolling, galvanizing lines, Automotive, Quality improvement