Research On Four Point Incremental Forming Key Theory And Its Simulation Experimental Analysis

Sheet metal incremental forming is a new rapid prototyping technology that has no need touse a die. It has been gradually used in aerospace components, car parts, medical devices andsome plate and shell parts which is one-piece, small batch, and varied due to forming withoutspecial die. For single point incremental forming process, due to the uneven force leads to theinstability of plank, the uneven wall thickness and the problem of stress concentration and lowforming efficiency, combining high efficiency advantages of multi-point forming, this paperproposed a new method of sheet metal parts forming the sheet metal，which is called incrementalmulti-point forming.This method not only reduces the defects in the single point incrementalforming process，but also avoids the difficulty in the accuracy of MPF controlling on a largenumber of substrates. Finite element simulation analysis and the forming experiments were usedto carry on the experimental research on the quality of incremental multi-point forming.Main research results of this paper：(1) Establish finite element model of four-points incremental forming with the shell elementmethod,Prepare corresponding MATLAB programs and finish the finite element solution of sheetmetal four points incremental forming,including:deriving the equilibrium equation of shellelement by through the force analysis of the element;giving the boundary condition of sheet metalforming according to the condition of four edges clamped;listing the yield condition of sheetmetal forming according to the characteristics of sheet metal forming;choosing the Prandtl-Reussincremental constitutive equation;deriving the shell finite element model of the rectangle4nodeswith12degrees of freedom.etc. Finished the external loading of finite element model and solvedsheet metal deformation and unit force.(2) Design and develop the forming machine,compare the thickness, size precision, residualstress, equivalent strain and forming force influence trend by the two path of forming accordingto the finite element simulation of four-point incremental forming a box and find that the secondpath can get better precision, more uniform wall thickness, and less residual stress, strain anddeformation force.but on the other side, the deficiencies is formed in the second path willdecrease the forming efficiency.(3) Finite element simulation of the forming process of the four pyramid with MARC, bydesigning the simulation experiment scheme and comparing the influence from the amount offeed, feed rate and forming angle in the forming process,it shows that the increasing of theamount of feed can leat to the increasing of equivalent strain,and the effect will be Moresignificant when the point is more closer to the tool;feed rate increases can also make the equivalent strain increase,but the influence will be significantly decreased when the feed rateincreases to a certain value;it also shows that the forming angle has little influence on theequivalent strain.This paper researched the basic theory problems in four-point incremental forming processand the influence on the forming quality from the molding method and process parameters in theprocess of forming box and four pyramid table is analyzed as a typical,which is promote to thedevelopment of the basic theory and technology of sheet metal incremental multi-point forming.