A study of basic mechanics in the multi-point single-point incremental combined forming of sheets metal

Abstract

Based on highly efficient multi-point forming and highly accurate single-point incremental forming, precise and efficient digital formation of three-dimensional metal sheets can be realised. In this article, stress states during the forming process were investigated based on mechanical equilibrium theory. The results showed that contact points of the matrix were subject to vertical tensile stresses when friction coefficient between metal sheets and matrix was relatively low and the angle between metal sheets and vertical plane was small. In other cases, the contact points of matrix were subjected to compressive stresses and dimplings may occur. For the axisymmetric workpieces, radial shear stress in the deformed zone decreased with the increasing radius of tool head and decreasing feed. The theoretical formula of forming force was deducted based on the principle of conservation of energy. According to this formula, the forming force was proportional to the thickness and yield strength of metal sheets and increased with increasing feed. Based on the study of multi-point single-point incremental combined forming, the parameters of tests and numerical simulations can be optimised.

Keywords:

• MP-SPI combined forming
• Sheet metal
• Stress analysis
• Strain analysis
• Forming force