ROD AND TUBE DRAWING

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ROD AND TUBE DRAWING
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ROD AND TUBE DRAWING
Specific work done for drawing rod by an
increment, Dl, is
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ROD AND TUBE DRAWING
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ROD AND TUBE DRAWING
Maximum Reduction Per Pass
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Effect of Friction
With redundant work included
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ROD AND TUBE DRAWING
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ROD AND TUBE DRAWING
Under non-ideal conditions, i.e., with friction
and redundant work, we define an efficiency, h,
where
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ROD AND TUBE DRAWING
Maximum Drawing Ratio (because the stress after
the die cannot be larger then the yield strength)
Under non-ideal conditions, we have
These are the maximum strains that can be
achieved per die.
Non-ideal
Ideal
sKen
sdKen1/h(n1)
sflow
sdKen1/(n1)
elnR
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ROD AND TUBE DRAWING
Die pressure
At yielding seff Y So, sx pY, where sx is
equal to sd near exit. So, p Y - sd
p
sx
p
Residual Stresses
Low reduction Compressive on surface and
tensile in interior High Reduction Tensile on
surface and compressive on interior.
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Tube Drawing
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SWAGING
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METAL FORMING
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LOCAL INSTABILITY IN TENSION TESTING OF THIN
SHEETS
In localized neck region, the strain along the
neck direction (2') is zero (plane strain
condition).
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SHEET METAL FORMING
Localized necking can give instability strain of
'2n', versus a value of 'n' is simple tension.
In practice, a diffuse neck (simple tension) is
followed by formation of localized necking. The
localized necking strain is influenced by sheet
anisotropy.
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FORMABILITY MEASUREMENTS
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FORMABILITY MEASUREMENTS
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FORMABILITY DIAGRAM
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FORMABILITY MEASUREMENTS
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SHEET METAL FORMING
Steels have Luder's bands