•Roll-bending –bending plates with a set of rolls
•Beading –bending the periphery of sheet metal into a cavity of a die to improve appearance and eliminate exposed edges
•Flanging –bending edges of sheet metal to 90 degrees
•Dimpling –punching a hole, followed immediately by flanging the edges
•Hemming –folding the edge of a sheet over itself
•Seaming –joining 2 edges of sheet metal by hemming
•Roll Forming –Multiple rolls to form linear products similar to extrusion
Roll Forming
Multi-stage rolling process for producing elongated sectional products from sheet metalTypical products are rain gutters and down spoutsCompetes with extrusion for some products
Deep Drawing Process
Stresses in Deep Drawing
Compressive hoops stresses in the flange
Drawing Parameters
•Wrinkling is caused by compressive (hoop) stresses that are induced as the blank moves into the die cavity
•Blankholder (or hold-down ring) pressure must be correct
•Too much pressure causes tearing, too little causes wrinkling
•Typically 0.7-1.0% of the sum of the UTS and yield strength
•If Do-Dp< 5T, deep drawing may be successfully achieved without a blankholder
Drawing Parameters
• Clearance is usually 7-14% sheet thickness
• Deep drawability is expressed by the limiting drawing ratio
• Normal anisotropy
• R for rolled sheet metal
Drawing Parameters
• Planar anisotropy determines whether earing will occur
• If DR=0 no ears form
• Ear height increases with DR
• Low DR and high Ravg is desired, but, tend to increase together
Earing in a drawn steel cup, caused by the planar anisotropy of the sheet metal.
Deep Drawing
The metal-forming processes involved in manufacturing a two-piece aluminum beverage can
•Products: pots, food and beverage containers, kitchen sinks, car fuel tanks
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