Estimation and Control of Drawbead Forces in Sheet Metal Forming

In sheet metal forming, drawbeads are often used to control uneven material flow which may cause defects such as wrinkles, fractures, surface distortion and springback. Appropriate setting and adjusting the drawbead force is one of the most important parameters in sheet forming process control. However, drawbead design and drawbead force adjustment still rely on trial-and-error procedures. This paper summarizes the guidelines in drawbead design, evaluates a number of mathematical models in estimating drawbead forces, and investigates the effects of sheet thickness, material properties, drawbead geometry and penetration on the drawbead force.