Dynamic Die Supply: Understanding Draw Bead Forces in Sheet Metal Drawing

As explored in “Engineering Angle: Draw Bead Restraining Forces in Sheet Metal Drawing Operations” by The Fabricator, advancements in automotive manufacturing have led to increased usage of aluminum alloys and high-strength steels. While these materials offer superior structural performance and reduced weight, they present challenges due to their constrained formability compared to mild steels.

When designing sheet metal drawing processes for automotive components, stampers rely on accurate information about restraining forces, typically provided by draw beads positioned along the die cavity perimeter. Draw beads have emerged as an efficient solution for achieving complex shapes without wrinkles or splits.

The restraining forces exerted by draw beads result from the bending and unbending of the sheet, accompanied by some level of stretching and friction. This method significantly reduces the binder force required to achieve the necessary restraining force compared to alternatives.

Experimental data indicates that with fixed beads, the clamping force ranges from 80% to 90% of the restraining force. Conversely, when relying solely on friction for restraining force with a flat binder, the binder force needs to be five to seven times larger, depending on the coefficient of friction. Without draw beads, larger press sizes are necessary to provide sufficient restraining force.

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Article with all rights reserved, courtesy of thefabricator.com

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