Design and Research of Heat Recovery Shield at Hot Rolling Mill in Steel Industry

This paper presents the heat transfer analysis of hot rolling bar (HRB), exactly between roughing mill and steckel mill. The bar is heated up to 1250°C in the furnace for three hours. The hot bar stock enters the roughing mill. Here, the bar stocks are fed for seven passes and the thickness is reduced to 25 mm. The elongate hot bar then travels approximately 126m in the open air surrounding over roller before entering the steckel mill. Transfer bar is rolled in steckel mill in 3 to 7 passes to achieve required thickness. It is adopted with the most sophisticated rolling technology of level-2 automation to achieve the target thickness, profile and flatness. There is a considerable loss of heat during this travel due to convection and radiation. This has been identified as the place, where the objective is to minimize heat loss taking place. Catia V5 is used for modeling and Ansys Workbench is used for thermal analysis.

Scrap Reduction in TMT Reinforced Bar Production by the Application of Lean Techniques

Lean aims to eliminate the non-value-added activity which affects the cost of production along with the scrap rate Lean is often considered as a collection of tools and practices for superior operational and financial performance, through process improvement. Lean is an improvement concept for operational performance in the manufacturing environment. In this work, lean techniques are applied to the manufacturing of random rods at a leading manufacturing company of Thermo Mechanically Treated (TMT) reinforced bars to reduce the scrap. The hot billet coming from the extrusion machine is sent to the rolling mill machine where the TMT bars are produced; this consists of three stages – roughing mill, shear cutting, and programming logical controller. During the shear cut operation performed on the billet, a large amount of scrap was being generated. To reduce this scrap and the non-value-added activities, lean techniques have been applied. Also, the size of the billet was changed to produce maximum yield. With this, the scrap rate at the rolling mill machine has significantly decreased leading to a notable reduction in the cost of production.

The Mechanism of Position-Mode Side Guide in Correcting Camber in Roughing Process of a Hot Strip Mill

The mechanism of the position-mode side guide in correcting slab centerline profile and camber in the roughing process of a hot strip mill (HSM) was analyzed using finite element simulation. The finite element model was established based on the actual size of the roughing mill and on the actual actuating time sequence of the roughing mill in China Steel Corporation (CSC), Kaohsiung. This work could be the first to give an insight into the mechanism of side guides in correcting the slab camber. Time sequence analysis was explored to visualize the progress of centerline profile variation and the interaction between the slab and the related roughing mill components at different moments. The history of reaction forces exerted on the slab was analyzed to explain the interaction between roughing mill components and the slab. The effect of the separation distance of side guide and the effect of the slab wedge on the centerline profile was investigated. A schematic model illustrating the reactions and the resulting moments exerted on the slab was created. By examining the force history, the cross-sectional strain/stress distribution, and the roll force across the horizontal roller, the correcting mechanism of the side guide could be elucidated. The simulation results provide further knowledge in selection and dimension design of side guide to improve the effectiveness of side guide in correcting the slab profile.