Page 449 - 04. Subyek Engineering Materials - Manufacturing, Engineering and Technology SI 6th Edition - Serope Kalpakjian, Stephen Schmid (2009)
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Section 16.13
Design Considerations in Sheet metal Forming
(b (C) §
a bend.
FIGURE l6.57 Application of notches to avoid tearing and Wrinkling in right-angle bending
operations. Source: Courtesy of Society of Manufacturing Engineers.
Poor Good
Poor
ux ur
Béllel'
(H) (bl
FIGURE l6.S8 Stress concentrations near bends. (a) Use ofa crescent or ear for a hole near
(b) Reduction of severity of tab in flange. Source: Courtesy of Society of
Manufacturing Engineers.
Bef O re
Sharp Sharp
radius radius After
(a) (D)
FIGURE |6.59 Application of (a) scoring or (b) embossing to obtain a sharp inner radius in
bending. Unless properly designed, these features can lead to fracture. Source: Courtesy of
Society of Manufacturing Engineers.
because of strain hardenin s and can fracture leadin to a stress concentration that
g
,
propagates the crack into the rest of the sheet.
Roll Forming. In general, the process should be designed so as to control spring-
back. Also, it is not difficult to include perforating rolls in the forming line, so that
periodic holes, notches, or embossings can be located on the roll-formed shape.