The development of a finite elements based springback compensation tool for sheet metal products

Abstract

Springback is a major problem in the deep drawing process. When the tools are released after the forming stage, the product springs back due to the action of internal stresses. In many cases the shape deviation is too large and springback compensation is needed: the tools of the deep drawing process are changed so, that the product becomes geometrically accurate after springback. In this paper, two different ways of geometric optimization are presented, the Smooth Displacement Adjustment (SDA) method and the Surface Controlled Overbending (SCO) method. Both methods use results from a finite elements deep drawing simulation for the optimization of the tool shape. The methods are demonstrated on an industrial product. The results are satisfactory, but it is shown that both methods still need to be improved and that the FE simulation needs to become more reliable to allow industrial application.

Iterative springback compensation of NUMISHEET benchmark #1

“…To be able to apply the shape modification field Φ to any mesh, including the generally larger and topologically different tool meshes, or even the analytically defined CAD geometries, the discrete field needs to be approximated and extrapolated by an analytical function Ψ . With this addition, the method is now called the Smooth Displacement Adjustment (SDA) method [4].…”

“…For a detailed discussion on the calculation of the approximation function the reader is referred to [4].…”

“…The DA-method [2] [3] performed very well on some academic example products, but for industrial products some practical issues had to be solved. This resulted in the Smooth Displacement Adjustment or SDA-method [4].…”

New method for springback compensation for the stamping of sheet metal components

“…The DA method shows better convergence than the FD method [2]. Tests of the DA method show that the convergence of the compensation depends on the part geometry as well as on material and process settings [4]. The functionality of the DA method can be described by a simple equation: +1 = − ( − ) [1].…”

A new shell element taking thickness-stretchability into account for mechanics-based springback compensation system

“…Gan and Wagoner proposed the displacement adjustment (DA) method, which is the most effective means of compensating for the springback in tools [1], and Karafillis and Boyce developed the force descriptor method (FDM) [2] [3]. Recently, various methods based on the DA method or FDM have been reported such as the comprehensive compensation method [4], the accelerated compensation method [5], and the smooth DA method [6], and so forth. However, the cause of springback, i.e., the bending moment before springback, is not considered in these methods.…”