A hierarchical quantification of inter- & intra-batch vibro-acoustic variability of deep drawn parts

Abstract

The cylindrical cup geometry, an archetype model, used to analyze the dimensional stability of the deep drawing process, is employed to study the vibro-acoustic performance subsequent to the forming simulations. Cylindrical cups are manufactured with a depth of 24 mm, thicknesses (0.97 mm & 1.21 mm) and using two different blank holder force (BHF) values (35 kN & 45 kN) in a controlled manufacturing process. A total of twelve cylindrical cups are considered for the study, as three replicates are included for each configuration. Experimental vibration results show that a significant variability is observed in both inter and intra batch-produced cylindrical cups. The higher BHF reduces the mean vibration values, while it increases the variance. Design of Experiments (DOE) studies, based on Taguchi orthogonal arrays, are carried out to characterize the individual effects of process parameters on the vibro-acoustic response levels. Deep drawing analysis and subsequent vibro-acoustic simulations are used to predict the variability observed in physical experiments qualitatively. It is shown that cups that are manufactured with higher BHF, higher friction, and misalignment have higher variability. Finally, a novel approach for achieving the vibro-acoustic variability targets using appropriate selectioof process parameters is presented.