Study On The Differential Temperature Drawing Of Nut Plate

Differential temperature drawing can reduce the yield streng in thelocal deformation zone, and cool the flange area to improve tensilestrength at the same time. Process cost could be reduced because thelimit drawing coefficient decreases. In order to study this technology, itwas necessary to understand the material respectively plastic deformationmechanism, mechanical characteristics and drawing deformation of heattransfer theory of stamping. Domestic and international studies hadshown more attention on the magnesium alloy, aluminum alloy andstainless steel materials, However, the application of this process inquality on carbon steel almost had no related research. In order to studythe feasibility and principle of differential temperature drawing processapplied to nut plate forming,10steel was chosen as the research material.Tensile tests whose temperature varies from0.001s^-1to0.1s^-1andtemperature varies from20℃to350℃were did. The results showed thatelongation increases when temperature increases. The ductility is best at0.001s^-1. When the temperature increases to350℃, blue brittle infracture macroscopic and microscopic surfaces had been observed. Itprovided a basis that heating temperature in this process applied to nutplate production should not be more than250℃elongation increasesslightly, with increasing temperature and plasticity property is better attensile strain rate0.001s^-1.The constitutive model Johnson-Cook was used to fit truestress-strain curves. The maximum absolute value of relative error aboutfitting is less than7.3%. So it fits well. Based on Deform, the constitutive model Johnson-Cook was used to simulate differential temperaturedrawing. The simulation and experiment, from the aspects of temperature,thickness, load-displacement curves, was compared. The results show that:the temperature distribution and thickness thinning of the simulation areclose to the experimental result. The simulation result aboutload-displacement curve predicts the forming load well. The absolutevalue of relative error is less than5%. So it can be used to choose the rightpress machine.Compared with room temperature drawing, it was obviousthat differential temperature drawing process can improve the minimumthickness and thinning rate was reduced by9%. This process applied in nutplate can reduce the rejection rate, thereby reduce the production cost.