Isotropic Material Testing for Ultra High Strength Steel Enclosures
Verify multi-axial yield limits and planar plastic strain ratios across three sheet axes to prevent catastrophic battery enclosure tearing under crash loads.
Draw Beads
Meaning
Form-controlling ridges machined into metal stamping dies restrict binder band movement during shallow and deep draw operations for battery enclosures. Positioned along the flange area of stamping tooling, draw beads exert localized restraining forces on metallic sheet stock to prevent wrinkling and tearing in pouch cell cups and aluminum battery housings. Controlling material flow into the die cavity enables uniform wall thickness across deep drawn cell covers.
Improper restraint results in micro-fractures or uneven flange margins.
Restraint Force
Friction and bending forces generated as aluminum sheet metal passes over draw beads determine the stress state within the forming zone. Tooling designers calibrate bead height and radius to achieve required tension without exceeding sheet metal strain limits.
Tooling Calibration
Dimensional tolerances on stamping dies require continuous monitoring because physical wear on draw beads alters the holding force over extended production runs. Tool steel coatings limit abrasion during high-speed stamping of aluminum battery cups.
Defect Prevention
Sheet metal splitting occurs when draw beads impose excessive clamping force, whereas insufficient restriction permits flange wrinkling that ruins sealing surfaces. Quality control protocols evaluate formed battery casings using optical scanning to confirm wall thickness uniformity and flange flatness before cell assembly. Flange defects jeopardize hermetic sealing.
Correct configuration of draw beads eliminates scrap during cup forming.