Sheet Forming Processes Flashcards
The main categories of sheet metal forming are:
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Shearing
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Bending
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Drawing
Shearing
mechanical cutting of material without the formation of chips or the use of burning or
melting
cutting blades are straight
Curved blades may be used to produce
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Blanking
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Piercing
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Notching
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Trimming
Shearing Operations
Fracture and tearing begin at the weakest point and proceed progressively or intermittently to
the next weakest location
Results in a rough and ragged edge
Types of Shearing
Simple shearing
sheets of metal are sheared along a straight line
Slitting
lengthwise shearing process
Piercing and blanking
shearing operations where a part is removed from sheet material by forcing a shaped punch through the sheet and into a shaped die
Blanking
the piece being punched out becomes the workpiece
Piercing
the punchout is the scrap and the remaining strip is the workpiece
Types of Piercing and Blanking
Lancing
piercing operation that forms either a line cut or hole
Perforating
piercing a large number of closely spaced holes
Notching
removes segments from along the edge of an existing product
Nibbling
a contour is progressively cut by producing a series of overlapping slits or notches
Dinking
used to blank shapes from low
strength materials such as rubber, fiber, or
cloth
Bending
the plastic deformation of metals about a
linear axis with little or no change in the surface area
Forming:
multiple bends are made with a single die
Springback
is the “unbending” that occurs after a
metal has been deformed
Angle Bending
(Bar Folder and Press Brake)
Bar folders make angle bends up to 150 degrees in sheet metal
Considerations for Bending
If the punch radius is large and the
bend angle is shallow, large amounts of
springback are often encountered
The sharper the bend, the more likely
the surfaces will be stressed beyond
the yield point
Figure
Roll Bending
Roll bending is a continuous form of three
point bending
Roll Forming
is a process by which a metal strip is progressively bent as it passes through a
series of forming rolls
Only bending takes place during this process, and all bends are parallel to one another
Seaming and Flanging
Seaming is a bending operation that can be used to join the ends of sheet metal in some form
of mechanical interlock
Flanges can be rolled on sheet metal in a similar manner as seams
Straightening
Straightening or flattening is the opposite of bending
Done before subsequent forming to ensure the use of flat or straight material
