Bending Operations
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Bending Operations

Views: 52     Author: Site Editor     Publish Time: 2017-12-22      Origin: Site


•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

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Deep Drawing Process

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Stresses in Deep Drawing

  Compressive hoops stresses in the flange

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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

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Drawing Parameters

• Clearance is usually 7-14% sheet thickness 

• Deep drawability is expressed by the limiting drawing ratio

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• Normal anisotropy

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• R for rolled sheet metal 

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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 

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Earing in a drawn steel cup, caused by the planar anisotropy of the sheet metal.

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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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