Four Methods of Bending Metal
Bending steel - pipes, tubes, beams, angles
Chances are that you were bending metal as a child. You
might have been making pipe-cleaner people. Or you might have
found paper clips fascinating. One thing is for certain, the
metal you were bending as a child was not steel beams or tubes,
and it never had to be strong enough to hold up a stadium roof
or a roller coaster.
As adults, we rely on curved metal beams, pipe, tubes, and
angles in everything from a simple park bench to spiral
staircases to some parts of modern skyscrapers. Visit any
airport or museum built in the past couple decades and count the
number of curved metal structures you find.
Have you ever wondered how they do it? I mean, how can you bend
a steel beam and still keep the strength to support an airport
roof? Well, there are four ways.
Rolling metal
Rolling is the best known way to bend metal, perhaps because it
is the least costly. Rolling uses an appropriate size die that
adjusts to the steel tube, angle, pipe, channel, bar or steel
beam and revolves at the same peripheral speed, turning in
opposite directions. As the metal passes through the roll, the
machine applies pressure to bend the tubing or the beam to the
desired radius.
Rolling is effective when the material - metal, plastic, glass,
whatever - must be bent a great deal. For instance, it can
produce bends up to 360 degrees. This method is ideal for
producing steel coils, spiral staircases and the like.
There are different kinds of rolling processes. Hot rolling
(above the recrystallization temperature) mostly produces sheet
metal. Most non-ferrous metal structures are rolled cold, but
steel is usually rolled hot.
Because rolling requires less set-up work and uses pre-made
dies, the cost is less than other ways to bend and form steel,
so companies often choose this when it suits their
specifications.
Bending metal with a mandrel
Mandrel bending is also fairly well known. In this process, a
metal shaft, or mandrel, is fitted inside the steel tube or
pipe. As the mandrel moves, it bends the metal around the
appropriate sized die to form the radius.
Mandrel works best when the steel tube or pipe has a heavy wall
and/or requires a tight radius because it prevents the material
from rippling. Mandrel can only bend steel tubing up to 180
degrees, but it produces a bend that is uniform all the way up
and down the pipe or tube. Obviously, this process is of little
use for bending metal beams or sheets, however, it is used in
bending exhaust pipes, molten glass and in very tiny cases,
jewelry.
The press method for heavier pipe and beam
The Press method is the third way to bend metal. The steel tube,
pipe, channel, bar or steel beam is fed through the press, which
applies pressure every 6 or 7 inches until the material is bent
to specifications Press is used to bend bigger, heavier beams,
pipes, channels, bars or tubes (24 inches or thicker) that do
not require a very tight radius.
This is a less common process than rolling or mandrel. However,
it is capable of producing large, load-bearing steel support
beams used for schools, roofing, skyscrapers, gymnasiums, malls
and bridges.
Table forming to bend metal tubing, pipes and beams
Table forming is the fourth process. The steel tube, pipe, or
beam is laid out straight and the ends are pulled around the
appropriate sized die to form the radius.
Table forming is used primarily to bend smaller, heavier steel
tubes, pipes, channels, bars or steel beams that require a tight
radius.
But if all that metal bending is too much for you, pick up those
pipe cleaners and wow your kids with the colorful pipe-cleaner
clowns you can form by bending metal at home.