Post on 12-Apr-2016
description
Drawing and Bending Process
-Dinesh Kumar R Ad-hoc Faculty Dept. of Production Engg NIT-Trichy
Drawing
Process of forming flat piece of metal into a hollow by means of punch and die cavity
Two Stress:– Circumferential Compressive stress- flange– Tensile Stress – Wall area
Types of Drawing Process
1. Shallow Drawing - Depth of cup formed is (h<d/2) upto half the
diameter2. Deep drawing - Depth greater than diameter (h>d)3. Moderate drawing - between half and full
(d/2<h<d) diameter (not normally done)
Necking
Necking is a mode of tensile deformation where relatively large amounts of strain localize disproportionately in a small region of the material
The resulting prominent decrease in local cross-sectional area provides the basis for the name "neck".
a form of plastic deformation associated with ductile materials, often metals or polymers.
Ironing
Ironing is a process to reduce the wall thickness of parts. Typically ironing should not exceed a depth of 30% of the material thickness.
Uniform thickness occurs Purely tensile process
Drawing Ratio
ratio of the maximum blank diameter that can be safely drawn into a cup without flange to the punch diameter
Drawing Ratio=Diameter of Blank/Diameter of cup formed from same blank
Deep Drawing
Blanking
Deep Drawing
Redrawing
Ironing
Doming
Necking
Seaming
Relatively complex 3
dimensional shapes can be
made out of sheet metal!
Examples of Deep Drawing
Bending
Beyond yield strength but below the ultimate tensile strength
Placed on die and bent using a simple punch.
Bending Mechanism
Spring-back
Roll Bending/ Forming
Used for bending boilers, cylindrical pressure vessels, and any other curved structure
Flexible adjustments
PICTURE FRAMES
Tube Bending and Forming
Work-piece Pressure Bar Clamp
* Internal filling is sometimes necessary to prevent collapse.
Tube Bending and Forming
Additional Operations
Beading- sheet metal bent into cavity
Flanging- edge bending of sheet metal
Bulging- tubular expansion
The End…!!!