万能轧制线重轨端部轧疤缺陷研究

STUDY ON THE SCAB DEFECT AT THE END OF HEAVY RAIL OF UNIVERSAL ROLLING LINE

针对河钢集团邯钢公司大型轧钢厂重轨端部轧疤缺陷问题,对万能轧机来料料型及重轨端部轧疤缺陷成因进行了深入研究。结果表明,重轨端部轧疤缺陷废品占比较大,种类较多,在万能轧机轧制过程中轧件头、底延伸不均导致咬入状态不良是产生缺陷的根本原因。针对万能轧机来料头、底部金属量失衡的问题,对开坯轧机帽形孔、轨形切深孔和轨形延伸孔进行孔型优化设计,使轧件头、底部位延伸比从1.0∶1.0改进为约1.0∶1.03,改善了万能轧机来料料形及其咬入条件,消除了缺陷产生根源;同时针对易发生啃咬粘钢的U2轧机水平辊孔型腰部及头腰连接弧部位,设计制作局部窄域石墨润滑防粘钢装置,对易粘钢部位进行石墨涂抹,有效抑制了轧件金属粘结在轧辊表面,降低了端部轧疤缺陷的产生几率,百米轨表面质量缺陷废品率降低了2.5%以上,年创经济效益约600多万元。

In view of the defects of heavy rail end scab in rolling plant of HBIS Group Hansteel Company,the material type of universal rolling mill and the causes of the defects of heavy rail end scab were studied.The results show that there are many kinds of defects in the end of heavy rail,and the main reason of the defects is the bad bite state caused by the uneven extension of the end and the bottom of the rolled piece.Aiming at the problem of unbalance of metal quantity at the bottom of the incoming head of universal rolling mill,the optimization design of the pass shapes of the cap hole,the deep cut hole of the rail shape and the extended hole of the rail shape of the cogging mill was carried out,the elongation ratio of the head and the bottom of the rolled piece was improved from 1.0∶1.0 to about 1.0∶1.03.The material shape and biting condition of the universal rolling mill were improved,and the source of the defects was eliminated.At the same time,aiming at the waist part of pass and head-waist connecting arc part of U2 mill,which is prone to nibble and stick steel,a device of anti-stick steel with graphite lubrication in local narrow area is designed and made,and the part of easy stick steel is coated with graphite,it can effectively restrain the metal bonding on the surface of the roller,reduce the probability of the end scab defect,and reduce the reject rate of the 100-meter rail surface quality defect by more than 2.5%,and create an annual economic benefit of more than 6 million yuan.