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High-capacity hot strip mill commissioned in record time

Posted on 09 Apr 2024 and read 512 times
High-capacity hot strip mill commissioned in record timeBy recently rolling the first hot strip, SMS group put the new high-capacity hot strip mill (HSM) at Jindal Steel Odisha Ltd (JSOL) successfully into operation. To JSOL’s great satisfaction, the construction and commissioning of the plant took place in record time, despite temporary restrictions caused by the Covid-19 pandemic. SMS implemented the new HSM in the Angul works of JSOL in the Indian federal state of Odisha. This is the first hot strip mill at this location — JSOL is a subsidiary of the O.P. Jindal Group.

The parent company has enjoyed a long relationship with SMS, which has now supplied several metallurgical plants to the Indian steel producer. Based on this confidence, JSOL placed an order with SMS in 2021 for the construction of a 1,780mm HSM, to be equipped with the world's most advanced technologies for hot strip production, especially when it comes to rolling of hot strip to thin final gauges.

SMS supplied the primary descaler, roughing stand No. 1 in 2-hi design with attached edger, roughing stand No. 2 in 4-hi design also with attached edger, transfer bar cooling system, HIBOX heat preservation hoods, mandrel-less coilbox, edge heating equipment, drum shear, secondary descaler, a seven stand finishing mill, laminar cooling and three downcoilers. SMS’s integrated business unit AMOVA supplied a coil conveying system, coil strapping machines, marking machine and an inspection line.

SMSPictured right: JSOL’s new high-capacity hot strip mill with the seven stand finishing mill

In the roughing mill section, slabs with 12m-length maximum, a thickness range from 180 to 260mm and a width range from 800 to 1,680mm are rolled down to transfer bar thickness. The range of hot strip thicknesses is 1.20 to 20mm. In total, JSOL’s HSM is designed for an annual capacity of five million tonnes.

The range of steel grades to be processed is very wide. These include, e.g. sophisticated grades such as HSLA, pipe grades and silicon steels. The share of harder material grades is more than 20%. Furthermore, very thin strips can be rolled reliably and stably. This is possible by implementation of various innovative rolling technologies.

Transfer bar cooling — for optimal temperature regulation in the roughing mill, SMS installed the newly developed transfer bar cooling system. The transfer bar cooling prevents uncontrolled air-cooling during oscillation and comes with favourable effects on temperature profiles. The effects on the rolling process in the finishing mill are positive. By equalising the temperature, product homogeneity is improved.

HIBOX heat preservation hoods — JSOL’s HSM is equipped with the latest-generation heat panels of the HIBOX type. This simplifies the inspection and maintenance of the elements and increases the service life by factor four compared to conventional preservation hoods. Using the HIBOX heat panels makes the finishing train’s rolling behaviour more stable and JSOL is able to shift the product mix toward smaller final thicknesses and/or higher strength steel grades. The HIBOX system comes with resilient savings in terms of energy, CO2 footprint and OPEX.

SMSPictured left: the finishing mill stands are provided with latest-generation actuators for precise and efficient rolling operation

Mandrel-less coilbox — arranged between the second roughing stand and the finishing mill, the coilbox forms transfer bar into coils and thereby equalises the temperature over the transfer bar length. Coiling the transfer bar prevents the inner windings from cooling. Material and heat are accumulated, providing a positive effect on the material to be rolled and the production process. The improved transfer bar temperature allows expansion of the product range to thinner gauges.

Edge heater — the edge heater, located upstream of the finishing mill descaler, uses inductive heating. The primary role is to enhance strip edge quality by maintaining optimal pre-rolling temperatures. This ensures flawless production, even for advanced grades.

Finishing Mill — the seven-stand finishing mill in 4-hi design is equipped with hydraulic adjustment systems, hydraulic loopers and latest-generation CVC plus (Continuously Variable Crown) combined work roll shifting and bending systems. Also part of the supply was the X-Pact Profile, Contour and Flatness process model (PCFC) being able to cope all requirements in terms of producing high sophisticated products with an exceptional wide range of properties and dimensions. PCFC calculates the optimal set points for the actuators of the CVC plus and bending system. This is why PCFC ensures the stability of the rolling process, highest product quality regarding strip geometry and a flexible rolling schedule.

The high-capacity HSM is completed by the laminar cooling system and three downcoilers. AMOVA as an integrated business unit of SMS supplied the coil conveying system strapping machines, marking machine and inspection line.