l21 - sheetmetal
TRANSCRIPT
-
7/23/2019 L21 - Sheetmetal
1/28
MECH152-L21 (1.0) - 1
Sheet Metalworking
-
7/23/2019 L21 - Sheetmetal
2/28
MECH152-L21 (1.0) - 2
Cutting Operations
Shearing by two sharp cutting edges.Plastic deformation penetration fracture
-
7/23/2019 L21 - Sheetmetal
3/28
MECH152-L21 (1.0) - 3
Shearing, Blanking and Punching
Shearing - Cutting on sheet-metal withstraight edges.
Blanking - Cutting sheet-metal with a closed
contour.Punching - Making holes on sheet-metal.
-
7/23/2019 L21 - Sheetmetal
4/28
MECH152-L21 (1.0) - 4
Sheet-metal Cutting
c = atc = clearance
a allowance
t thickness
Blanking!
Blanking punch dia. Db- 2c
Blanking die dia. Db
Punch
"ole punch dia. Db
"ole die dia. Db+ 2c#.$%to &.%
-
7/23/2019 L21 - Sheetmetal
5/28
MECH152-L21 (1.0) - 5
Sheet-metal Cutting
Small clearance
'arge clearance
Cutting force StL
S Shear strength of sheet-metalt Sheet-metal thickness
L 'ength of cutting edge
or, Cutting force #.(TtL
T = )ltimate tensile strength of sheet-metal
-
7/23/2019 L21 - Sheetmetal
6/28
MECH152-L21 (1.0) - 6
Sheet-metal Cutting Operations
Cut-off
Parting
Slotting Perforating *otching + Seminotching
-
7/23/2019 L21 - Sheetmetal
7/28
MECH152-L21 (1.0) - 7
Sheet-metal Cutting Operations
ine blanking -
close tolerances
and smooth
edges in one
step.
rimming - Cutting operation to remoe e/cess metal
Shaing - Shearing with ery small clearance to obtain
accurate dimensions., secondary or finishing operation.
-
7/23/2019 L21 - Sheetmetal
8/28
MECH152-L21 (1.0) - 8
Bending
0- bending 1dge - bending
-
7/23/2019 L21 - Sheetmetal
9/28
MECH152-L21 (1.0) - 9
Bending 2nalysisBA = 2 A( R + Kbat ) / 360
whereBA bending allowance,A bend angle,R bend radius, tstock thickness,Kba = stretch factor.
or 34 $t,Kba #.55 6 for 3$t,Kba #.%.
Spring back,
where 27 include angle of sheet-metal part
27b include angle of bending tool
w width of sheet-metal
Bending force D die opening dimension
Kbf = &.55 0-bending
Kbf = #.55 edge bending
b
b
A
AASB
=
D
TwtKF
bf
$
=
-
7/23/2019 L21 - Sheetmetal
10/28
MECH152-L21 (1.0) - 10
Bending 2nalysis
Spring back
8ie-opening
dimension
-
7/23/2019 L21 - Sheetmetal
11/28
MECH152-L21 (1.0) - 11
Bending Operations
Straight flanging Stretch flanging Shrink flanging
"emming Seaming Curling
-
7/23/2019 L21 - Sheetmetal
12/28
-
7/23/2019 L21 - Sheetmetal
13/28
MECH152-L21 (1.0) - 13
8rawing
c Clearance
Db blank diameter
Dp Punch diameter
Rd die corner
radiusRp Punch corner
radius
F drawing force
Fh holding force
MECH152L21(10)14
-
7/23/2019 L21 - Sheetmetal
14/28
MECH152-L21 (1.0) - 14
8eep 8rawing
9nitial step bending of edge straightening of side wall
hinning and drawing final cup shape
-
7/23/2019 L21 - Sheetmetal
15/28
MECH152L21(10)16
-
7/23/2019 L21 - Sheetmetal
16/28
MECH152-L21 (1.0) - 16
8rawing 2nalysis
> Blank diameter can be calculated from the conseration of
olume based on the final olume of the part.
> 9f the limits on the drawing ratio, reduction and thickness-
to-diameter ratio are e/ceeded, the blank must be drawn in
steps or haing annealing between the steps.
> Process optimi?ation!
@ Punch and die corner radii
@ friction
@ depth of draw =per step