Incommensurate vibro-acoustic performance due to in-process blank holder force variation during deep drawing process

Abstract

Single-stage forming is widely used in automobile industry due to less cycle times, cost-effectiveness and ease of implementation. The continuously adaptable blank holder force (BHF) systems help produce defect-free components during the deep drawing process. However, this manufacturing process induces a significant amount of variability both at geometry and functional performance of the component. A systematic investigation of the effect of small geometrical changes on the vibro-acoustic properties is carried out using a combination of simulations and experiments. The influence of BHF and friction coefficient on vibro-acoustic properties is investigated through forming simulations. The forming analysis results-geometry profile and thinning-are used as an input to predict the vibro-acoustic behaviour of the formed component. The small geometric profile and thickness variations are significant and affect radiated noise-directivity pattern and sound power levels by 1.4 dB. Two physical components are manufactured using a single-stage deep drawing process. The natural frequencies and mode shapes obtained in free-free boundary conditions vary between the two components up to 20% for the first six flexible modes.The sound power levels between the actual parts varied by 2 dB(A). Finally,

Surrogate model–based inverse parameter estimation in deep drawing using automatic knowledge acquisition

“…The former result makes intuitively sense due to two reasons: First, in contrast to the linear model, the quadratic model also contains terms to express cross-correlations between different input parameters. Cross-correlations exist for example between the blank holder force and the friction coefficient, since the sensitivity of the draw-in with respect to the blank holder force increases with higher friction [1,2] coefficient and vice versa. Second, the dependency between input parameters and draw-in is not necessarily linear, since for example the effect of large drawbead heights saturates at a certain level where material flow is almost prevented.…”

“…Deep drawing is one of the most used production processes in sheet metal forming and is used in a wide range of industries [1]. L.-E. Elend estimates that manual fine-tuning after tool manufacturing, called tryout, consumes up to 30% of the overall tool cost [2], which is confirmed by S. Schulte [3].…”