Speaker
Description
To improve the accuracy of forming simulations advanced friction models are increasingly used in industry. These models account for the physical properties of the sheet, tool and lubrication and describe the tribological conditions during the forming operation. One of the main influencing factors on the tribology system, and therefore the friction coefficient, is the surface roughness of the tools. Until now, it is often assumed the tool has the same surface roughness over the whole area. In reality however, the tool might have different surface conditions dependent on the type and location of the tool. That is, the blank holder might be differently polished then the punch, and sharp radii might have a finer tool roughness compared to flat areas. This paper investigates a significant number of tool measurements from different try-out and production dies from Volvo Cars, and quantifies the effect of local surface conditions on product quality and process robustness. The study is motivated by Volvo Cars where the majority of forming simulations are performed to secure die tryout, i.e. to solve as many problems as possible in forming simulations before the final design of the die and milling of the casting.