22-01-2013, 11:39 AM
Forgiing
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Objectives
• This chapter provides fundamental of metal working process for forging
in order to understand mathematical approaches used in the calculation
of applied forging loads required to cause plastic deformation to give the
final product.
• Classification of metal forging methods is also provided with
descriptions of defects observed from the forging processes.
• The solutions to tackle such defects will also be addressed.
Introduction
• Forging is the working of metal into a useful
shape by hammering or pressing.
• The oldest of the metalworking arts (primitive
blacksmith).
• Replacement of machinery occurred during
early the Industrial revolution.
• Forging machines are now capable of making
parts ranging in size of a bolt to a turbine
rotor.
• Most forging operations are carried out hot,
although certain metals may be cold-forged.
Forging operations
Swaging is used to produce a bar with a smaller
diameter (using concave dies).
Swaging at the ends, ready
for next forming process.
• Swaging provides a reduced round
cross section suitable for tapping,
threading, upsetting or other
subsequent forming and machining
operations.
Mechanical press forging
Mechanical press
• Crank press translates rotary motion into
reciprocating linear motion of the press slide.
• The ram stroke is shorter than in a hammer or
hydraulic press.
• Presses are rated on the basis of the force
developed at the end of the stroke.
• The blow press is more like squeeze than
like the impact of the hammer, therefore, dies
can be less massive and die life is longer than
with a hammer.