Tube Drawing

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 ?

  1. Coefficient of friction
  2.          Strength of job material

  3.         Temperature of job in which tube drawing process is occurring

  4.            Die angle

  5.          Speed of drawing

  6.           Reduction area (ratio)



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