The Deformation Mechanism Analysis On Sheet Based On The Contact Normal Pressure In Roll Forming Process

It is important to define the way the friction which drives sheet forward to meet the demand of forming products in the roll forming acts on the sheet deforming so that we can calculate the roll forming energy parameters and determine the transmission,strength verification of roll forming machine et al.and can provide guidance for production.An Abaqus finite element simulation model is established to acquire the distribution of contact normal pressure in roll forming and analyze its effect on the deformation of the sheet during the process.The simulation results show that the distribution of contact normal pressure on different region of both surfaces sheet:the distribution of contact normal pressure on up surface are corners and around the corners;the down surface contact normal pressure distribute in the flange edge,the middle flange and the web around corners.Then an experimental platform is built to measure roll force and roll torque et al.to caculate the friction coefficient and used the pressure measurement film prescale to measure the contact normal pressure in roll forming,and compared with the result of the simulation,in order to verify the accuracy of the finite element simulation model.It is shown that the simulation of the contact normal pressure distribution on the both surfaces sheet agree with the result of the experiment,and the relative error of the contact normal pressure is smaller.The simulation can be used to simulate the friction in the actual conditions.The regression model is used to analyze the relationship between the strains at the flange and corner of the sheet,and conclude that the relationship of the contact normal pressure and the isotropic strain.It is shown that the main strain at the flange and corner are different.Specifically,the contact normal pressure lead the sheet metal to the longitudinal strength stain,the shear strain and the longitudinal bending strain at the flange;the contact normal pressure lead the sheet metal to the longitudinal strength stain,the transverse bending strain,and the out-of-plane bending strain at the corner.And based on the distribution of each region and the isotropic strain relationship,expound the variational regularity of stress and strain at the flange and corner under the effect of the contact normal pressure on sheet:as the sheet goes deeper into the rollers,the sheet is subjected to the tension and compression state of different strain at the flange;At the corner the regions of maximum strain distribution,which the sheet is subjected to,are different.