Research On Numerical Simulation And Forming Defect In Single Point Incremental Sheet Metal Forming

The single point incremental forming(SPIF)controlled by computer is a flexible manufacturing technology and considered as one of the most promising technology in the field of sheet metal forming.Compared with traditional forming methods,SPIF has been free of die manufacturing process.Therefore,because of it’s low cost and short production cycle,it is used to small-lot.However,in the further research on this forming method,it is discovered that the poor fitness has been the main restrictions for the development of SPIF.According to the current science and technology,the highest precision of SPIF is± 3mm,but in the filed of industry the precision need to be ± 0.2mm.The promotion and application of SPIF in the advanced manufacturing field is lagerly stopped by this requirement.Therefore,in this thesis,the springback is mainly studied,because the springback has a dominant effect on the precision of the forming parts,and several method to reduce springback are proposed.Finally,some other forming defects including thickness thinning,sag,rupture and indentation are also researched,and measures to restrain these defects are presented at the same time.The contents and results are listed as follows:(1)The theoretical issues in SPIF are researched.The changing of the wall thickness,the principal stress,the principal strain and the forming force in SPIF are analyzed.The forming force is measured through orthogonal experiment under the condition of different parameters.It is concluded that the relationship bettween the forming force and processing parameters.(2)The stress,strain and displacement under the condition with the forming angle of 30°,45° and 60°;layer spacing of 0.5mm,1.0mm and 1.5mm;tool head’s radius of 3mm,4mm and 5mm are analyzed by ABAQUS.(3)The springback in SPIF is studied by experimental method.Firstly,the effect of spindle speed on springback is studied separately.Then,the springback of different shape parts are studied and three typical parts are selected: outerconvex shape,conical shape and inner convex shape.Finally,the forming angle,layer spacing,feed speed and machining depth are studied through orthogonal experiment.The influence of these factors on the springback is obtained through the above research,which lay the foundation for the later research.(4)Some other forming defects are studied in the progressive forming process.The effects of forming angles on the thickness of the workpiece are studied and the maximum sag under different processing parameters is studied through orthogonal experiments.In addition,the surface rupture defects,indentation defects and metal accumulation are studied and the corresponding measures are proposed to reduce the forming defects.(5)The springback is an inevitable phenomenon in SPIF.There are many ways to reduce springback.In this thesis,the effect of negative compensation method on reducing the springback is mainly studied,which provides a reference for the further research.