Study On Macro And Micro Deformation Mechanism Of Single Point Incremental Forming With Isothermal Local Loading Of Sheet Metal

Manufacturing highly complex,high-precision,high-quality and affordable products is the need of the current manufacturing industry.Sheet metal isothermal local loading single point incremental forming technology is a more flexible and scientific manufacturing process.Compared with the traditional single point incremental forming technology,the isothermal local loading single point incremental forming technology is conducive to higher requirements of forming accuracy and quality,especially suitable for small batch,multi deformation,relatively poor plasticity at room temperature,low forming capacity at medium and high temperature and other production processing.Due to the lack of research and development of isothermal local loading single point incremental forming technology,its macro deformation mechanism and micro deformation behavior have not been comprehensively explained.In order to study and analyze the isothermal local loading single point incremental forming technology more scientifically and effectively,it is necessary to fully study the macro deformation mechanism of metal sheet,and analyze the macro deformation mechanism more comprehensively and concretely from the micro angle of grain size change.This passage combines the theory of progressive forming and plastic forming,and by using ANSYS/LS.DYNA software,the numerical simulation of isothermal local loading single point incremental forming is carried out.The effects of forming temperature,tool head radius,feed rate and initial plate thickness on the stress.strain,sheet thinning rate,quality and forming limit of 6061 aluminum alloy and AZ31B magnesium alloy in the process of isothermal local loading single point incremental forming are analyzed.At the same time,by using MARC software,the microstructure evolution model is established,and the relevant simulation technology is used to simulate and predict it,and the change of micro mechanism such as grain size after isothermal local loading and single point incremental forming is analyzed.Finally,combined with the microscopic metallographic observation to-verify the plastic forming experiment,through the study of the change of the macro and micro mechanism of metal sheet,we can more scientifically solve the problems of plastic deformation and forming quality.The results show that the forming temperature,tool head radius,feed rate and initial plate thickness have significant influence on the plastic forming of 6061 aluminum alloy and AZ31B magnesium alloy.When the forming temperature is in the range of 200??300?,the average grain size of sheet metal increases with the increase of forming temperature.When the forming temperature is 250?,the sheet metal has the best forming performance.When the radius of forming tool head radius is 4mm-6mm,the average grain size and increasing trend.When the radius is 5mm,the grain size is relatively uniform,the thickness of the formed part changes uniformly,and the thinning rate is small.The feed rate has a certain influence on the forming limit,thinning rate and grain size of sheet metal.With the increase of feed rate,the forming quality and precision are worse and the smoothness is lower and lower.The average grain size of the formed part will increase with the increase of feed rate.When the feed rate is 1.Omm,the forming performance is the best.When the initial sheet thickness of sheet metal is 0.8mm?1.5mm,the forming limit increases with the increase of the initial sheet thickness,and the average grain size in the processing area of the corresponding forming part gradually increases,thus the sheet metal shows good forming accuracy and formability.