| The development of the automobile industry is becoming more and more rapid.Due to the increasing requirements for safety performance and energy saving and emission reduction,advanced high-strength steel is widely used in various models due to its advantages of cost,safety,light weight and environmental protection.However,the stamping process of advanced high-strength steel is not exactly the same as that of traditional high-strength steel.Due to the high yield strength and hardness,the test and simulation analysis results are quite different in the stamping process of parts.For the debugging situation of the mold site,it is found that the local temperature of the mold and the sheet material is particularly high,far higher than the room temperature;the friction of the rounded area of the concave mold is particularly serious.Preliminary analysis reasons:(1)The stress of the advanced high-strength steel plate changes greatly during the deformation process,and the internal lattice of the metal produces large deformation strain energy;(2)the increase of strength and hardness,and the increase of local normal pressure cause friction of the contact surface The temperature increases significantly,so it is necessary to consider the self-heating problem during the stamping process.The temperature rise caused by deformation heat and frictional heat is an intuitive and invisible change,and the process is also a complex process of dynamic change.The deformation heat and friction heat depend on plastic deformation and friction motion.After the temperature rises,it has a certain influence on the properties of the metal material.At this temperature,the metal continues to be stamped and deformed,and the energy generation is related to the current temperature.Therefore,The numerical simulation analysis of this process requires a lot of theoretical research work.The mutual influence should be calculated according to the calculation result of the previous step and the coupling of the temperature field and the physical field such as the stress field and the strain field.Firstly,considering the relationship between the properties of the sample and the temperature,the tensile test of the sample at different temperatures and different strain rates is carried out by a hot tensile tester to obtain the true stress-strain curve of the metal material,and the trend is summarized to establish the plasticity.Structure relationship.In addition,other thermal correlation coefficients,including thermal expansion rate,specific heat capacity,thermal effect conversion coefficient,and temperature-dependent friction coefficient model,were imported into the numerical simulation software to derive and verify the deformation heating mechanism and friction heating mechanism.The relationship between temperature and deformation and friction further establishes a thermo-mechanical coupling stamping model that considers deformation heat and frictional heat.In addition,through the trial production test,the final result of the trial production of the U-shaped part is obtained,and compared with the calculation results of the new stamping model and the traditional stamping model,the difference and accuracy of the calculation results under the two models are compared,and the new stamping forming method is obviously obtained.The accuracy of the results has increased by nearly 12.1%.Considering the continuous production,the temperature of the heat transfer of the previous part often remains on the mold.Therefore,the influence of different mold temperatures on the metal stamping result is considered.In addition,considering the problem of large rebound of the duplex steel during processing,The method of "warm forming" of duplex steel is proposed.Combining the deformation heat and friction heat,the high temperature is discussed on the stamping result.It is found that the results under the "warm forming" condition are obviously more resilient and the amount of reduction is very large.fulfil requirements. |
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