SheetMetal Forming

1
Sheet-Metal Forming
IE 204 Manufacturing Processes
Dr. Zühal ERDEN

• Shearing
• Removing a blank of suitable dimensions from a
  large
• sheet by subjecting it to shear stresses between
  a punch
• and a die.
• Low-carbon steel is the most commonly used sheet
  metal.
• Aluminum, titanium ? for aircraft and aerospace
  appl.

Atilim University / Dept. of Industrial
Engineering
2
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
Atilim University / Dept. of Industrial
Engineering
3
Processing Parameters
IE 204 Manufacturing Processes
Dr. Zühal ERDEN

• Shape and materials for the puch and die
• The speed of puching
• Lubrication
• The clearance between the puch and the die
• (As clearance the punch force )

Atilim University / Dept. of Industrial
Engineering
4
Punch Force
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
The maximum punch force F 0.7TL(UTS) where,
T Sheet thickness L Total length sheared
(perimeter of hole) UTS Ultimate tensile
strength of the material
Atilim University / Dept. of Industrial
Engineering
5
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
Punching
Blanking
Atilim University / Dept. of Industrial
Engineering
6
Punch and die shapes
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
Atilim University / Dept. of Industrial
Engineering
7
Tool and die materials
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
Tool steels (generally) For high production
rates ? carbides Clearance Conventions Clearance
is a function of the type of material,
thichkness and size of the hole and its proximity
to the edges of the sheet Clearance for softer
materials lt Clearance for harder materials The
thicker the sheet, the larger the clearance
Atilim University / Dept. of Industrial
Engineering
8
2. Bending Sheet and Plate
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
Atilim University / Dept. of Industrial
Engineering
9
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
Bend allowance, Lb Lb ?(RkT) ? Bend angle
in radians R Bend radius K Constant T Sheet
thickness For an ideal case(neutral axis is at
the center of the sheets thickness) k0.5
Atilim University / Dept. of Industrial
Engineering
10
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
Hence Lb ? R (T/2) As a
guideline k values range from 0.33 for Rlt2T to
0.5 for R gt2T
Atilim University / Dept. of Industrial
Engineering
11
Minimum Bend Radius
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
The radius at which a crack appears on the outer
surface of the bend. Usually expressed in terms
of thickness of the sheet or plate such as
2T, 3T, 4T etc.
Atilim University / Dept. of Industrial
Engineering
12
Springback
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
Elastic recovery when the load is removed in
plastic deformation.
Atilim University / Dept. of Industrial
Engineering
13
3. Deep Drawing
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
Atilim University / Dept. of Industrial
Engineering
14
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
Deep drawability is expressed in terms of the
limiting drawing ratio (LDR) LDR Maximum
blank diameter/Punch diameter Do/Dp
Atilim University / Dept. of Industrial
Engineering
15
Redrawing
IE 204 Manufacturing Processes
Dr. Zühal ERDEN
Atilim University / Dept. of Industrial
Engineering