Measures for controlling the material flow when extruding sheet-bulk metal forming parts from coil

Abstract

The increasing demand for lightweight design requires functional integration. This poses challenges to conventional manufacturing processes due to the rising geometrical complexity of components. The application of bulk forming operations to sheet metal, named sheet-bulk metal forming (SBMF), is one approach to overcome these challenges. Currently, mainly pre-cut blanks are applied in research of SBMF. Production from coil, in contrast, would combine the advantages of SBMF with the advantages of manufacturing from a coil regarding high output quantity. To research SBMF from coil, a lateral and a backward extrusion process are set up. In addition to a reduced geometrical accuracy of the parts, which is known from SBMF of pre-cut blanks, an anisotropic material flow is identified as a coil-specific challenge. The aim of this research is to investigate measures that extend the forming limits by means of a material flow control. For this purpose, a combined numerical-experimental approach is applied in order to analyze and evaluate an adaption of the width of the coil, the feed width, and the local friction as measures for material flow control. Particularly local adaptation of friction by means of modified tool surfaces reduces the anisotropic material flow and improves the geometrical accuracy of the parts.

Keywords

• extrusion
• sheet metal
• cold forming
• sheet-bulk metal forming
• material flow control