| Due to its hexagonal close-packed(HCP)structure and limited number of active slip systems,magnesium alloy sheets(such as AZ31B)exhibit extremely low plastic deformation capacity at ambient temperature.In order to overcome these challenges,some forming has been carried out.Process research to solve these problems,an effective solution is to use the forming process at high temperatures,but the cost is generally higher.Therefore,it is very important to find an alternative advanced manufacturing technology that can be achieved through low cost and high efficiency.Increase the forming temperature to improve the formability and forming accuracy of the magnesium alloy sheet.This paper proposes an innovative frictional heating auxiliary method,which uses the friction heating between the tool head and the sheet metal.This method does not require additional heating equipment,has an extremely simple device structure and is quite economical.Therefore,one of the main purposes of this article is to explore this novel and simple experimental device to form magnesium alloy plates more conveniently and quickly.Then,in order to evaluate and optimize the process capability of frictional heat incremental forming,an experimental study was carried out on the AZ31 B sheet according to the experimental design.In addition,based on response surface method and analysis of variance,the influence of feed rate,tool head speed and tool head diameter processing factors on formability is discussed,and the establishment of a quadratic regression model can successfully predict the forming limit angle.Through the comparison between experiments and the model,the correctness of the model is verified,and the incremental forming process of magnesium alloy sheet is improved and supplemented,which is of great significance to the incremental forming technology of magnesium alloy sheet.The experimental results show that the most important factor affecting the formability of the magnesium alloy sheet incremental forming technology is the speed,followed by the feed rate and the tool head diameter,and the interaction between the feed rate and the tool head diameter;the optimization results show that the maximum forming The optimization results show that when the plate thickness is 1.6mm,the maximum forming limit angle of 73° is obtained at a speed of 2481r/min,a feed rate of 1mm,a tool head diameter of 16 mm,and a forming temperature of 140°C;Verification shows that the quadratic regression model can be satisfactorily within the range of less than 10% Estimate the correlation between the formability and the processing parameters considered.The frictional heat incremental forming process is a complex elastoplastic large deformation process with geometric nonlinearity,material nonlinearity and nonlinear boundary conditions.The frictional heat incremental forming finite element model of magnesium alloy sheet is established through ABAQUS software and the digital model of actual parts is established through CATIA software.The forming process is analyzed The geometric accuracy of the sheet metal,the thinning of the wall thickness and the stress conditions can be used to determine the most vulnerable area for prevention and subsequent improvement.This work attempts to visually express the deformation characteristics in the forming process,and in this process,with the help of finite element analysis,three-dimensional part digitization and experimental research,it is more intuitive to see the changes in different periods,and according to their different degrees of forming strain,the formation There are three different parts,grades are divided into early,middle and final stages.Understand the deformation behavior,and evaluate the geometric accuracy and thickness distribution of the above-mentioned formed parts.In addition,the deformation stress and plastic strain at different forming stages are also evaluated numerically.The experimental results show that due to the limitation of the experimental conditions during the forming process,it will be different from the ideal model.The bending phenomenon occurs first in the early stage of forming,which makes the accuracy of the upper corner part the worst,and there are obvious convex marks on the lower corner part;The side wall of the actual part The stable area is reduced by 11% compared with the theoretical stable thickness.The sidewall area of the part does not reach a stable thickness at the beginning,but the thickness reaches the minimum when the forming depth is about15 mm,so it is most likely to occur when the forming depth is 10-20 mm When it ruptures,it is of guiding significance for the follow-up research;When the equivalent strain reaches the stable depth of the wall thickness,it basically remains unchanged at about 0.471.It can be observed that the maximum stress value increases with the increase of the forming stage. |
PDF Full Text Request