Study On The Effect Of Servo Process On Sheet Formability

Compared with the traditional mechanical press,the forming process of the servo press has obvious advantages: flexible,adjustable and controllable.The use of servo forming technology has made it possible to optimize and improve the shaping problems of the new lightweight body materials.In typical servo modes,the change of forming speed and unloading processes are ubiquitous and applied,which has a significant effect on the formability of the metal sheet.The effect of speed change on the formability of strain rate-sensitive materials has been discovered,but the effect on strain rate-insensitive materials remains to be explored.Moreover,the effect of the change in forming speed on materials with different sensitivities needs further investigation.In addition,though the unloading process will affect the performance of the material and its stamping formability,the effect of specific unloading positions and unloading times on material's property and its deep drawing formability still need to be verified and found.Based on the research vacancy,relevant experimental verification will be carried out with the help of Dynaform finite element simulation and the lightweight materials such as Q195/AL6061/HSLA/medium manganese steel.And the effects of forming speed change and unloading progress on sheet metal formability will be explored.The contents of this article include the fal ows:(1)The hemispherical FLD experimental mold will be designed to verify the impact of unloading process on sheet metal forming.(2)The impact of speed change on the formability of strain rate sensitive or insnsitive materials(MAT24 and MAT64)will be explored baseing on Dynaform numerical simulation,so dose the study of the material formability with different strain rate sensitivity.The influence is compared through the thickness curve of the central section of the forming part and the history curve of the first principal stress of different area units.(3)Tensile experiments were performed on Q195/AL6061/HSLA/medium manganese steels with different unloading positions and unloading times.The stress-strain curves of the Q195/AL6061/HSLA were used to verify the influence of the unloading positions and times on the material properties.Correction functions of the stress-strain curve of medium manganese steel based on different unloading positions and times were established through supplemental comparison experiments.(4)The forming limit curves of Q195 under different loading conditions influenced by the unloading positions and unloading times were obtained baseing on the Dynaform numerical simulation.The verification experiments of the numerical simulation results were completed and limit strain of the complete sheet material was obtained with the help of FLD experimental mold.