Analysis of the Sheet Wrinkling Variation and Causes in the Case of Mini Drawn Parts

Abstract

The present paper analyses the results of investigations concerning the size and effects of sheet wrinkling in the case of mini cylindrical drawn parts made from aluminium alloy sheets. The wrinkling occurs in the mini drawn part walls when the blankholder is missing from the die structure or it is driven with an excessive force. By comparing to macro scale processes, the manufacturing of mini parts usually involves new concepts concerning the establishment of the following parameters: tool clearances, tool dimensional parameters, blank dimensions, working process parameters etc. In the case of mini deep drawing such objectives cannot be simply achieved by reducing the process from macro to mini scales. The present work was devoted to study the particularities of the wrinkling that occur during mini deep drawing processes and affect the quality of the mini drawn parts. The experimental investigations were performed using a mini tool having the following main components: punch with a flat bottom, die and an annular blankholder plate. The tool was installed on a mini deep drawing device having the following main components: mobile grip - connected to machine mobile head; fixed grip; helical spring - used to regulate the blankholder force and placed between the fixed grip plate and punch support. The simulation was performed using the DynaForm software and the applied criterion of plasticity was the Barlat 89 criterion.