Unit IV Origional
Unit IV Origional
Unit IV Origional
Introduction
For a V-die
Max bending force, P = (UTS)LT 2
W
UTS – Ultimate tensile strength
Drawing
Schematic illustrations: (a) before and (b) after blanking a common washer in a
compound die.note the separate movements of the die(or blanking) and the punch
Progressive dies
Merits
•High strength
•Good dimensional accuracy and surface finish
•Relatively low cost
Demerits
•Wrinkling and tearing are typical limits to drawing operations
•Trimming may be used to reach final dimensions
Applications
•Roofing
•Ducting
•Vehicles body buildings like 3 wheelers, 4 wheelers, ships,
aircrafts etc.
•Furniture, House hold articles and Railway equipment
ROLL FORMING
Process where sheet metal strips are passed through consecutive set
of rolls and bent in consecutive stages and then sheared into
specific lengths and stacked continuously.
Forming speed: below 1.5 m/s (300 ft/min)
Examples: Door panels, picture frame, and gutters.
Stretch Forming
First used to form metals in the 1900’s. A sheet metal blank is clamped over a
die, and the entire assembly is lowered into a tank filled with water. The air in
the cavity is evacuated, and an explosive is detonated at a certain height above.
MAGNETIC-PULSE FORMING
Also called electromagnetic forming. Energy stored in a capacitor bank is discharged
rapidly through a magnetic coil. Magnetic field crosses metal tube (conductor)
creating eddy currents which have an opposing magnetic field.
(b)
(a)
Figure 16.45 (a) Schematic illustration of the magnetic-pulse forming process used to form a
tube over a plug. (b) Aluminum tube collapsed over a hexagonal plug by the magnetic-pulse
forming process.