Research On Simulation Analysis Of Tire Post-cure And Cooling Deformation

The post-cure cooling process is an important link in the tire production process.After the in-machine vulcanization is completed,the tire is taken out of the vulcanizing machine and continues to be cooled.During this process,the tire is gradually cooled to room temperature,and the tire material components will undergo thermal expansion or thermal contraction due to temperature changes,resulting in changes in the size and shape of the tire.Therefore,it is of great theoretical significance and engineering application value to carry out the post-cure cooling deformation simulation research for guiding the tire post-cure cooling process.Taking 215/65R16 passenger car radial tire as the research object,the postvulcanization cooling deformation process was studied by simulation and test methods.The post-cure cooling deformation simulation of the tire involves the thermalmechanical coupling process.In order to accurately simulate the tire post-cure process,the thermal material parameters of the tire rubber were tested,including the rubber thermal physical property parameters,the rubber vulcanization reaction heat,and the rubber vulcanization kinetic parameters.The dry heat shrinkage rate of the cord and the thermal expansion coefficient of the rubber under temperature were tested;the creep characteristics of the cord under high temperature were tested,and the time-hardening power law model was used to characterize its creep behavior.Using ABAQUS/Standard solver combined with user subroutines,and using the thermal parameters of tire materials obtained from the test,a tire curing model was established,and the curing degree and temperature history of the tire curing and post-cure cooling process were predicted.The tire vulcanization temperature measurement test results show that the test at 8 temperature points is consistent with the simulated temperature history,and the obtained tire temperature history can be used as the boundary condition for the postcure cooling deformation simulation.A finite element model of tire post-cure cooling deformation was established based on ABAQUS.The sequential thermal-mechanical coupling method is adopted,the temperature field at the end of the in-machine vulcanization is used as the initial temperature condition of the tire post-cure cooling deformation simulation,and the temperature history of the tire post-cure process is used as the simulated boundary temperature condition.The thermodynamic parameters of the tire can be predicted to predict the tire size under different post-curing inflation pressures and the tire size after direct air cooling.The influence of cord and rubber thermodynamic parameters on the post-vulcanization cooling deformation of the tire is studied.The results show that the thermal shrinkage characteristics of the cord alone cannot be considered in the simulation to obtain the exact size after the tire is unloaded at the end of postvulcanization and inflation;the curtain is considered in the simulation.The tire unloading state at the end of PCI can be effectively simulated when the creep characteristics of the cord are used.In the simulation,the tire section width(SW)obtained by considering the thermal expansion coefficient of rubber and the elastic modulus of the cord at different temperatures is smaller,and the result is closer to the real value.The outer contours of the finished tires under different cooling conditions were scanned.The comparison between the test results and the simulation results showed that the tire SW obtained by post-cure inflation(Post-cure Inflation)simulation was very different from the measured value,and the relative error did not exceed 0.8 %;The difference between the SW simulation value and the measured value of the tire without natural cooling in the PCI process increases,and the relative error is about 1.2%,but it is still within a reasonable range;the simulation of the maximum outer diameter(OD)of the tire under different working conditions The difference between the value and the measured value is small,the maximum is only 0.27%,which shows the validity of the prediction model.Based on the simulation method,the influence of the presence or absence of PCI process,different post-cure inflation pressures and different tire ejection time on the outer edge dimensions of the finished tires was explored.The research shows that the PCI process can effectively inhibit the shrinkage and deformation of the tire during the post-cure cooling process,and the SW of the non-PCI tire is always smaller than that of the PCI tire.Significant changes;with the extension of time after the tire is out of the mold,the tire SW shows a decreasing trend.The influence of rubber vulcanization degree on tire outer edge size is explored.The analysis results show that the tire outer edge size obtained by using rubber with different vulcanization degrees is very different from the original scheme,and can be temporarily ignored in the simulation.