1 Introduction
A engineer is always focused towards challenges of bringing ideas and concepts
to life. Therefore, sophisticated machines and modern techniques have to be constantly
developed and implemented for economical manufacturing of products. At the same time, we
should take care that there has been no compromise made with quality and accuracy.
Pipes have got numerous applications. They are used for transmission of fluid from one place to
another. Also pipes form an integral part of many machines, supporting frames for furniture.
Pipes in zig-zag form are used in condensers. In automobiles, pipes are used for exhaust and in
radiators. These pipes are available in straight form. But as per some applications, some
curvatures of bend are required to be given to the pipe.
1.1 objectives
Manual bending can be employed, but we cant get good finish and accurate form. There are
chances of even flattening of pipe. Special machines have to be employed for this requirements.
The machines can be operated manually or by motor power.
Bending the pipe to the specified radius without flattening is the most critical part of the machine.
The time required should be minimum to increase productivity. The machine should also
compromise of attachments and accessories so that various sizes of pipes can be bend to various
diameters and adjustments can be made for a range of radius of curvature.
This machine is useful for bending pipes within workshop. It does not require more space. It is
compact. The machine manual, power with not much of effort to bend the pipe. Pipes of different
materials like aluminum, copper, brass, Ms, galvanized pipe can be bend.
2 literature survey
The effect of anisotropy on wrinkling of tube under rotary draw bending
Kourosh Hasanpour1,*, Mahmoud Barati2, Behnaz Amini3 and Mehrdad Poursina1
1Department of Mechanical Engineering, Faculty of Engineering, University of Isfahan, P.O.Box 81746-73441, Isfahan, Iran
2Department of Applied Mechanics, Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran
3Department of Mechanical Engineering, Islamic Azad University, Khomeinishahr Branch, Iran
(Manuscript Received February 9, 2012; Revised August 4, 2012; Accepted October 3, 2012)
Summary
Rotary draw tube bending is one of the most complex tube forming processes
subject to different process parameters such as material
properties and geometry. This process is being practiced in more and more
applications in industry due to its high efficiency, high forming
precision and quality. However, improper process parameters can lead to wrinkling
which restrict the thin walled tube bending.
Therefore, the prediction and prevention of wrinkling is very important. Despite its
importance, the effect of anisotropy on the occurrence
of wrinkling was not considered in the literature up to now. In this investigation, a
quantitative study on the wrinkling of thin walled tube
bending is carried out through a finite element model of the process using velocity
integral parameter, which is used for the detection of
wrinkles. The other methods usually warn the wrinkling initiation with no precise
location prediction. In addition, the effects of some
process parameters, specially normal and planar anisotropy on the tube wrinkling
are investigated. It is shown that increasing normal and
planar anisotropy (increasing r0 and r90 values) result in a decrease in tube
wrinkling.
CONCLUSION
The rotary draw bending of a thin-walled tube was simulated
to investigate the tube anisotropy effects on wrinkling.
The tube material considered anisotropic and Hill quadratic
yield criterion was employed. Two kinds of anisotropy, i.e.
planar anisotropy and normal anisotropy were considered in
this study. Based on this investigation, the following conclusions
can be drawn:
(1) With an increase in normal anisotropy value, the wrinkling
of tube will decrease, so the onset time of wrinkling will
increase. The tube normal anisotropy influence on wrinkling
in comparison with isotropic tube is significant and cannot be
ignored.
(2) With an increase in planar anisotropy value (value increase
of r45 ) and when r0 = r90 =1 , velocity integral parameter
does not follow a particular trend.
(3) With an increase in planar anisotropy values of 0 r and
90 r ) and when 45 r =1 , the absolute value of velocity integral
parameter will decrease and it can be noted that tube wrinkling
is decreased as well.
