Visualization of shapes for deep-drawn cup bottoms by flatness measures using a roundness measurement machine

Deep-drawing products are subjected to defects resulting from different causes. Generally, the bottom of the formed shape is not expected to present any defect and research works do not normally address this matter. However, there are some factors that favor defects at the bottom of the deep-drawn product, such as the bad state tools and equipment are in, the tool and/or sheet's lack of flatness and the presence of lubricant trapped between the tool and the cup. The present work establishes a methodology for visualizing the defects that appear at the bottom of cups by flatness measurements using a roundness measurement machine. The methodology consists in measuring the flatness for different circumferences and drawing the results by using an application in Matlab, and has been applied to control DC-05 and AISI 304 DDQ steel cups. The possibility of using this technique for such purposes has been demonstrated.