Tube
Drawing
In this blog we will learn about Tube drawing process
What is Tube drawing process ?
It is a process in which a larger hollow cylinder or tube or
pipe diameter is shrink into smaller
diameter of hollow cylinder /pipe/tube by drawing through a die.This process is
often done after hot working of tubes so that we can get good surface finish
and other benefits
What are the types of tube drawing ?
Tube
sinking : In this process a tube is simply draw through a
die to reduce its outside diameter and inside diameter. As you can see there is no internal support is provide
inside so the surface finish produce inside the pipe/tubes are uneven due to
that surface thickness increase.
Fixed
Plug : In this process a mandrel is provide inside the tube. In
this the mandrel(plug) is fixed at its position . this provide better surface
finish in inside diameter.This process is use limited because long tubes can’t
be drawn and area reductions are limited in this kind of process.
Floating
Plug/Mandrel : In this
process a floating mandrel/plug is used .In this case the position of
the plug/mandrel is controlled by the tangential and normal forces of the
tubes/pipes of the material.The friction force in floating plug/mandrel is more
than the Fixed Plug.
Moving
Mandrel : In this process both the tube and mandrel are
move together from the die.It produce high quality tubing with very good dimensional accuracy.
What are the advantages of tube drawing process?
1.High surface finish
2.Good mechanical properties of tube due to the strain
hardening effect
3.Can produce thin and smaller diameter tubes
4.Good dimension tolerance
5.Irregular tubes shapes can be produced by this method
Formula used for Drawing process
σd = Yield Strength of the material
B = µcot(α)
µ =
co-efficient of friction
α = half die angle
R1 = radius of tube at the exit of the die
Ro = radius of tube at the entrty of the die
What are the factors the effects tube drawing process ?
- Coefficient of friction
Strength of job material
Temperature of job in which tube drawing process is occurring
Die angle
Speed of drawing
Reduction area (ratio)
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