Study On Effect Of Forming Trajectories On Incremental Sheet Forming Result

Incremental sheet forming(ISF) is a novel, flexible and dieless sheet formingprocess. It’s very suitable for individual part or low batch parts due to omit the time andmoney requirements of die tools. Using a principal of layer manufacturing of rapidprototyping and forming by a progression of localised deformation, Part was dividedinto many layers forming trajectory along axial direction, and then manufactured byforming tool which moved as the forming trajectory in contour line way. ISF has ahigher formability than traditional stamping forming, a good repeatability, and cancontrol metal flow and manufacture complicated surface shape. So ISF has a goodpotential prospect and has been obtained lots of research and application since1990s.During ISF process, a reasonable forming trajectory of a given part is the key tothat the given part can be quickly manufactured whether or not. So effects of formingtrajectory on ISF was studied in this thesis.Firstly, basic manipulation and installation of a finite element method (FEM)model of ISF were adjusted and a cone FEM model was built and validated by athickness contrast between simulated and counted by sine law.Secondly, Based on strain analysis of simulation experiment, mechanical of ISFwas validated to be a plane strain forming mechanism(wall direction was stretchedwhile thickness direction compressed).And the results of studied processing parametershowed that: a spiral moved forming trajectory can get a best performance;Step size hasfew influences on the minimum thickness while great on the place where the minimumoccurred and the time needed. So the step size should be a moderate value. ISFformability has a positive relationship with tool’s diameter, but the oversize tool can’t toform the small detail.Thirdly, the variable parameter thought was introduced in ISF form stampingforming, Base on thickness distribution, the forming trajectory of ladder step size wasbrung up, and its influencing on the minimum thickness and the place occurred and thetime needed were analyzed with application of orthogonal test and range analysismethod. Then a new method to decide weight coefficient by ratio of amplitude rangewas brung forward, the multiple aim was changed into one single aim by this newmethod.Then the optimized answer was obtained by BP network－geneticalgorithm(GA), and finally validated by a new simulation experiment.Then,A automobile part named left taillight support was manufactured by ISF in two steps andvariable step size forming trajectory.Fourthly, A contrast of mechanical property was did by tensile test between beforeand after forming.A pyramid with height of120mm, half cone angle of30°was practicalmanufactured by ISF,12samples were cut form the pyramid in8differences place.Thesine law was validated by thickness analysis. The result of12samples tensile testindicated that: the sample before ISF forming has a good plasticity, but tensile strengthand yield strength had a similar value. After ISF forming, the plastic material hadalready changed into brittle material, plasticity was dramatically dorp,with a94%extent,and the plasticity strain was not more than5%. While tensile strength has a51%extentincrease.And the place has nothing to do with elongation and tensile strength.