Design And Implication Of A Control System For Mandrel Retaining In Seamless Tube Mill

At present,the most advanced technology of rolling seamless steel tube is the Mandrel Retaining Premium Quality Finishing(PQF)continuous mill in the world.Mandrel retaining system is an important part of PQF continuous mill,the mandrel retaining system is related to the wall thickness accuracy,ellipticity,steel tube inner and outer surface quality,heat tool consumption,yield and production efficiency of the rolled seamless steel tube,the mandrel retaining system can guarantee the high quality seamless steel tube produced by PQF continuous rolling mill.Mandrel retaining system is extended from the Multi-Stand Pipe Mill(MPM)to PQF,it is proved that the mandrel retaining system is indispensable for seamless steel tube.The position control,speed control and torque control of the mandrel retaining system are related to the stability,rapidity and accuracy of the whole system.The paper combined the φ 159mm seamless steel tube production line of Baotou Steel(Group)Corporation to introduce the process,according to the technical specifications,the hardware part of the mandrel retaining system was designed,including motor,drive system,control network,PLC and configuration.According to the technical data of motors,the overload ratio of motors was analyzed,and the weak magnetic point of motors was selected;Designed of four quadrant frequency converter and selection for mandrel retaining system;Designed the PLC and configure the frame according to the control network,field operation station,encoder and input/output signal;The hardware configuration was completed by using Control Builder M software,and the whole hardware design is completed.The paper analyzed the position control theory,speed control theory and torque balance theory of mandrel retaining system;drawled torque balance principle diagram and electrical principle diagram;designed torque matching block diagram of controller and torque software control block diagram and programed.The setting program of the drive parameters,the coordinate position control program,the torque balance program,encoder synchronization program and encoder alarm program were listed in detail in the paper.In the later stage,the iba Analyzer software that installed in PDA was used to analyze the field curve,and the hardware design,theoretical analysis and program were tested.Through the analysis of the curve,the design of Through the analysis of the curve,the design of the mandrel retaining system could meet the technical specifications and the expected requirements.