Research On Surface Quality Control In Incremental Sheet Forming

Incremental sheet forming is an innovative flexible manufacture technology,which utilizes a simple tool to form complex sheet part without expensive die. As animportant problem, surface quality influences incrementally formed parts validationand appearance. In this thesis, the factors that affect the surface finish most wereclassified and analyzed to find out the level and principle of each factor. Typical conepart was employed and comparison experiments were designed to get the effect ofscallop height, tool path, multi-passes, tool radius, original sheet roughness, frictiontype and lubricant on surface quality. After that, a new oblique roller-ball tool wasdeveloped to improve the surface quality at the situation of large step size in replace oftraditional rigid tool. The project is supported by the Important National Science&Technology Specific Project of China “The Innovation Platform of Precision FormingTechnology and Equipment”(No.2011ZX04016-051) and Shanghai Jiao TongUniversity2113rdphase of Talent Project. The main research results are as follows:1) The contact number mathematical model between tool and sheet was built upwith the parameters of scallop height, wall angle and tool radius. With this model,numbers of friction between tool and sheet can be predicted, according to whichadhesive friction and ploughing effect can be evaluated.2) The most appropriate scallop height for specific original-roughness sheet wasconcluded by the analysis of surface finish under different scallop heights. The resultsshowed that using the scallop height a bit larger than original sheet roughness canprocess surfaces which were not worse than original sheet. This can provide basic toolpath reference in the AA1010incremental sheet forming.3) Rolling friction can reduce the friction force between tool and sheet instead ofsliding friction by roller-ball tool. With this method, the forming time and surfaceroughness can be decreased at the same time under the larger pre-set scallop height tool path.4) Grease CXI can work better than others in incremental sheet forming. Themixture of MoS2and grease CXI can reduce the adhesive friction and ploughing effect.But taking the safety and environment into consideration, grease CXI works best inAA1010incremental sheet forming. After that, processing the DC05steel at the samelubrication situation demonstrates the grease CXI is indeed the best choice inincremental sheet forming. Another result showed that the adhesion of metal played animportant part in lubricant choice in ISF.5) Innovative oblique roller-ball tool was developed to increase the one-timewall angel instead of conventional roller-ball tool. New roller-ball tool broadens theapplication of incremental sheet forming. The large-angle cone part and complexflower part were processed to prove the validation of new tools.