Hyundai Steel tasked Primetals Technologies with the supply of a large bar mill and a small bar and wire rod mill for its Dangjin plant. The two multi-line rolling mills are capable of producing an annual one million tons of special steel billets as well as straight and coiled bars, with dimensions from 5.5 to 350 millimeters. The products are used in the manufacture of engine and transmission components used by Hyundai-Kia Automotive Group. The processed grades include carbon, special alloy, spring, bearing, and free-cutting steel. Sensors and electronics integrate with mechatronic packages, thus equipping the mill for Industry 4.0 applications and constituting the next step in long rolling for automotive at Hyundai Steel.
FIRST MILL: LARGE BAR MILL
The first mill is a large bar mill (LBM) that rolls blooms into finished large round and square products, as well as into intermediate billets. A 2-high reversing breakdown stand is followed by a finishing and sizing train with continuous-gap-adjustment stands equipped with an under-load roll-parting system for automatic gap control.
The mill’s capacity of one million tons per year is split into some 800,000 tons of billets that serve the second mill, and 200,000 tons of other large bars. The product mix includes 150 mm and 180 mm billets, 80-350 mm rounds and 85-180 mm finished squares that are 10-12 meters in length.
The starting bloom is 530×390 mm with lengths of 3.5-8 meters, weighing 5.7-13 tons. The mill runs at a maximum speed of 1.1 meters per second with a maximum production rate of 200 t/h. The produced bars measure 4-12 meters in length, with bundles weighing 2-10 tons.
SECOND MILL: SMALL BAR AND WIRE ROD MILL
The second mill—a small bar and wire rod mill (SBWRM)—combines lines of small bars, rods, and bars-in-coil. Billets are rolled in a continuous rolling mill with original Red Ring Series 5 stands. The rod outlet features Morgan equipment such as No-Twist Mills and Reducing/Sizing Mills, High-Speed Laying Head, and Stelmor Conveyor.
With an annual capacity of 800,000 tons, the SBWRM produces some 400,000 tons of wire rod, 300,000 of small bars, and 100,000 tons of bars-in-coil. The product mix includes 5.5-26 mm wire rod, 16-100 mm rounds, and 16-60 mm bars-in-coil. The starting materials are 150 mm and 180 mm billets produced by the large bar mill; 200 mm billets can also be used.
The mill runs at a maximum speed of 110 meters per second for wire rod and 18 for bar, with a maximum production rate of 160 tons per hour. Straight bars are finished-sized by a Kocks block and produced in 4-10 meter lengths in 1-5 ton bundles. Finalized coils of wire rod have an inner diameter of 900 mm and an outer diameter of 1,250 mm.
The bars-in-coil are finished-sized by a Kocks block and have a diameter of 1,000 (inner) and 1,350 mm (outer). Coils from both the wire rod and the bar-in-coil lines weigh 1.7-3 tons, and are handled by a common combined vertical and horizontal conveyor system.
Hyundai plans to produce 400,000 tons of wire rod and 600,000 tons of straight bar and bar-in-coil per year.