Research On Forming Characteristics Of Target Sheet Based On Sheet Incremental Forming Process With Auxiliary Sheet

The CNC incremental metal sheet forming is a new flexible manufacture technology.Traditional incrementally formed parts have the problems of poor surface quality and uneven wall thickness distribution.Modern high-precision sheet metal parts have higher requirements for surface quality and well thickness uniformity of target parts.In order to improve the surface quality and wall thickness uniformity of the formed parts,the incremental forming method of sheet incremental forming process with auxiliary sheet were conducted.In this study,1060 Aluminum sheet was used as the target sheet and 304 sus as the auxiliary sheet.The characteristics of incremental forming of 1060 Aluminum sheet and incremental forming with auxiliary sheet are analyzed and compared.The researches are as follows:(1)The forming feasibility of sheet incremental forming with auxiliary sheet was verified.The strain,surface quality and wall thickness distribution in the deformation zone of the target part were measured and compared between the conventional sheet incremental forming(CSIF)and the one with auxiliary sheet.It was found that the sheet metal deformation during the processes both of the conventional and modified method belongs to shear deformation.The surface quality and wall thickness distribution uniformity of the target forming parts by sheet incremental forming with auxiliary sheet are significantly improved,and there is no obvious indentation on the surface.(2)The influence of different process parameters on the surface quality of the target part in the sheet incremental forming with auxiliary sheet was studied.It is found that the surface morphology of the target part has no obvious wave crest and wave hollow,and the material is distributed uniformly,and the surface roughness of the target part has little relationship with the incremental step size,and the processing time cost can be reduced by using a larger incremental step size.With the increase of the diameter of the forming tool head and the decrease of the forming angle,the surface roughness decreases,and the lubricant that between the auxiliary sheet and the target sheet has little effect on the surface quality of the target part.It was also corroborated that the initial thickness is a variable that influence the surface quality of the target parts.(3)The influence of different process parameters on the wall thickness distribution of the target part in the conventional sheet incremental forming and the one with auxiliary sheet was studied.It is found that there will be a serious phenomenon of thin strip thinning in the conventional incremental forming.Compared with conventional incremental forming,there will not be a phenomenon of thin strip thinning in the sheet incremental forming with auxiliary sheet,in the same process parameters,the minimum thickness of the target part is larger.With decreasing the step size,wall angle and increasing the diameter of the forming tool head,the wall thickness uniformity increases and the thinning rate decreases.(4)The formability of the target sheet in the sheet incremental forming with auxiliary sheet was analyzed.Compared with conventional sheet incremental forming,the formability of 1060 Aluminum sheet in the sheet incremental forming with auxiliary sheet becomes worse,and the increase of incremental step size and initial thickness of target sheet improves the formability of 1060 Aluminum sheet in both of the conventional and modified method.Three common failure modes in the sheet incremental forming with auxiliary sheet are pointed out.