Abstract:
A new plant for special steel long products was commissioned in recent years at Dangjin, South Korea, for Hyundai Steel.Two multi-line rolling mills supplied by Primetals Technologies are capable to produce yearly 1 million tons of billets,straight and coiled bars,with dimensions from 5.5 to 350 millimeters.The products are used for manufacturing engine and transmission components used by Hyundai Kia Automotive Group.The processed grades include carbon,special alloy,spring,bearing and free-cutting steel.The demanding requirements posed by the automotive industry are met by the supplied state-of-the-art equipment and processes.Blooms coming from a 4-strand continuous caster,also supplied by Primetals Technologies,are rolled by the first mill (LBM) into finished large round and square products,as well as into intermediate billets.With a yearly capacity of 1,000,000 tons and an hourly productivity of 200 tons,the LBM processes continuously-cast blooms measuring 530x390 mm crosswise and 3.5-8 m lengthwise,which are hot charged to the re-heating furnace and descaled.A 2-hi reversing breakdown stand is followed by a hot-scarfing station,then by finishing and sizing trains,where CGA stands are equipped with under-load roll parting system for automatic gap control.After normal/slow cooling facilities,bars are made ready for dispatch.Shearing and sawing systems are provided along the mill for dividing and emergency operation.Beside finishing large rounds ranging from 80 to 350 mm in diameter,the LBM prepares billets with square dimension of 150 or 180 mm.The billets feed a second mill (SBM),which combines the lines of small bars,rods and bars-in-coil.The SBM has a yearly capacity of 800,000 tons and is designed to roll 160 tons per hour,a record value for a combination mill.After re-heating,the billets are rolled in a continuous rolling mill with 16 RedRing® Series 5 stands.The rod outlet further rolls the bar in two 2-stand prefinishing mills,followed by an 8-stand Morgan No-Twist® mill and a 4-stand Morgan Rod Reducing/Sizing Mill.Wire rod with a diameter from 5.5 to 26 mm is finished at a maximum speed of 110 m/s.A laying head deposits the rod rings onto an 11-zone Morgan Stelmor® conveyor for flexible cooling operation,which is followed by the coil forming station.Bars are finished at 18 m/s maximum speed by a sizing block,supplied by Kocks (Germany).A 102 m-long and 12.5 m-wide cooling bed is provided for straight bars with diameters from 16 to 100 mm,and followed by bundling and handling facilities.Bar-in-coil products with diameter from 16 to to 60 mm are coiled at the pouring reel station,which is followed by a conveyor for cooling according to the required temperature curves.A combined vertical pallet / horizontal hook handling system is provided to service coils from both the rod and bar-in-coil outlets.Several water boxes for thermo-processing as well as shearing and sawing systems for dividing and emergency operation are provided.The SBM is particularly designed for low-temperature rolling,to improve the metallurgical structure and mechanical properties of end products and enhance flexibility during the rolling operation.Advanced sensors and electronics integrate with mechatronic packages,thus implementing Industry4.0 tenets to ensure a consistently high quality of the products.Several customer's benefits are obtained,including optimized conversion cost,flexibility to meet market changes,high product quality,reduced floor personnel.
