Research On Forming Mechanism Of Local Heating Roll-die Forming Of Ultra High Strength Steel

Local heating roll-die forming of the ultra-high-strength steel is a new method to realize high-precision variable-section roll-die forming of ultra-high-strength steel sheets.Mastering the roll-die forming law of ultra-high-strength steel materials at high temperature is the premise basis.In this paper,DP980 and QP980 ultra-high-strength steel materials were used as the object,and the mechanism of local heating roll-die forming of ultra-high-strength steel was studied by the combination of finite element simulation analysis and experiment.Through the high temperature uniaxial tensile test,the stress and strain curves of DP980 and QP980 materials were obtained.The basic mechanical properties of the material were obtained by processing the obtained data,which provided the data foundation for subsequent analysis.Based on ABAQUS,a finite element analysis software,the thermal coupled finite element model of DP980 was established at four temperatures of 22?,400?,450?and 500?,and the finite element simulation was carried out.The simulation results analyzing from equivalent stress,equivalent strain,roll forming moment,forming force and rebound shows that the forming quality is better at 500?.The thermal coupled finite element model of QP980 was established at 200?,250?,300?,350?,400?,450?,and the finite element simulation was carried out.The simulation results analyzing from equivalent stress,equivalent strain,roll forming moment,forming force and rebound shows that the forming quality is better at 350?.Compared with the forming at room temperature,the forming force and the moment are greatly reduced at a high temperature,and the forming quality is good.A local heating device was designed and installed based on the mechanical structure of the normal temperature roll-die forming machine.By comparing various heating methods,it was proposed to perform non-contact electromagnetic heating on the formed sheet by electromagnetic heating.Based on the original SIMOTION motion control system of the roll-die molding machine,TM3 1 was used to expand the I/O,and the electromagnetic heating machine and the water-cooling machine were integrated into the original control system.The temperature was controlled based on the incremental PID algorithm to achieve high precision temperature control of the heating device.In the host computer,the heating control program was written in VC++and it was embedded into the original software.The control program in the slave computer was written by ST language.The heating system was debugged and verified,and the control accuracy was within±1 ?,which meted the temperature control requirements.In this paper,local heating roll-die forming mechanism of ultra-high strength steels DP980 and QP980 were studied.The thermal coupling finite element simulation analysis was used to obtain the roll-die forming law of the material under high temperature.An electromagnetic local heating method was proposed to complete the development of the heating control system.The research content of this paper has certain theoretical significance and engineering value for the development of high temperature roll forming equipment.