Research Of Sheet Metal Based On Single Point Incremental Formability

Sheet metal based on single point incremental forming (SPIF) is an innovative flexible forming technology without die and suitable for development and manufacture of new, varieties and small batch products. It has broad application prospect in the automotive, aerospace, household appliances, medical equipment and other fields. In practical production of incremental forming, selection of processing parameters affects the forming quality and solving the incremental forming defects still need further research on incremental forming mechanism. In this thesis, numerical simulation model suitable for SPIF was built based on ANSYS/LS-DYNA finite element software, and mechanism of SPIF was analyzed by forming conical frustum parts and finally numerical simulate and experiment to study the affect of process parameters on formability of SPIF. The main research contents are as follows:1) Under the software platform of Matlab, the problem of complex forming path loading was successfully solved by programming and run GUI application and realize the simulation procedure of SPIF completely.2) Mechanism of SPIF was analyzed from stress, strain and thickness distribution. The conclusion shows that: ? All elements in the forming area belong to three-dimensional stress state, two tensile stress and one pressure stress; ?The strain state are associated with forming region and forming path. When loading circular path, micro-deformation zone is compressive type of deformation, transitional-deformation zone is the mixture of compress and shear deformation, uniform-deformation zone and deforming zone are all pure shear deformation. When loading Straight path, all of the deformation zone are compression deformation; ?Thickness distribution based on cosine law of SPIF part is applicable only to second half of transitional-deformation zone, uniform-deformation zone and deforming zone.3) Numerical simulation and experimental verification were designed to get the effect of the original sheet thickness, vertical incremental step and shape of part on formability of SPIF and tests were performed to probe into the choice of lubricant used in incremental forming process. The conclusion shows that: As a result of wear that between the forming tool and sheet metal, deformed zone thickness of thin sheet became thinner than thick sheet. Vertical increment step is too small or too big didn't beneficial to incremental forming, too small will not cause the regeneration and recrystallization in metal for the temperature effect, too big will cause the tendency of nonuniform deformation and the increase of friction. Compared to cone frustum, pyramid frustum has smaller average strain capacity, more uniform deformation and more thicker sheet. The effect of using lubricating grease with extreme pressure additives as the lubricant of incremental forming is excellent because of its high pressure resistance and good adhesion.