文档介绍：Chapter 17: Sheet-Forming Processes
DeGarmo’s Materials and Processes in Manufacturing
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Introduction
Sheet metal processes involve plane stress loadings and lower forces than bulk forming
Almost all sheet metal forming is considered to be secondary processing
The main categories of sheet metal forming are:
Shearing
Bending
Drawing
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Shearing Operations
Shearing- mechanical cutting of material without the formation of chips or the use of burning or melting
Both cutting blades are straight
Curved blades may be used to produce different shapes
Blanking
Piercing
Notching
Trimming
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Metalforming
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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
Punch and die must have proper alignment and clearance
Sheared edges can be produced that require no further finishing
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Figure 17-1 (Left) Simple blanking with a punch and die.
Figure 17-2 (Right) (Top) Conventionally sheared surface showing the distinct regions of deformation and fracture and (bottom) magnified view of the sheared edge. (Courtesy of Feintool Equipment Corp., Cincinnati, OH.)
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Figure 17-3 (Right) Method of obtaining a smooth edge in shearing by using a shaped pressure plate to put the metal into pression and a punch and opposing punch descending in unison.
Figure 17-4 Fineblanked surface of the ponent as shown in Figure 17-2. (Courtesy of Feintool Equipment Corp., Cincinnati, OH.)
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Types of Shearing
Simple shearing- sheets of metal are sheared along a straight line
Slitting- lengthwise shearing process that is used to cut coils of sheet metal into several rolls of narrower width
Figure 17-5 Method of smooth shearing a rod by putting it pression during shearing.
Figure 17-6 A 3-m (10ft) power shear for mm (1/4-in.) steel. (Courtesy of Cincinnati Incorporated, Cincinnati, OH.)
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Piercing and Blanking
Piercing and blanking are shearing operations