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By David Leonhardt
When you were just crawling out of the cradle, you were probably already bending metal. You might not have been trying to bend steel beams or tubes, but you might have been bending metal paper clips, or even twisting your parents' cutlery beyond recognition (a few years later!). Or you might have simply preferred making pipe-cleaner clowns.
As adults, we rely on curved metal beams, pipe, tubes, and angles to hold up huge sweeping stadium roofs and to shape spiral staircases and park benches. 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 bend metal? I mean, how can you bend a steel beam and still keep the strength to support an airport roof? Well, there are four metal-bending techniques.
Rolling to bend 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.
Mandrel to bend metal
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.
Press to bend metal
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
Table forming is the fourth process for bending metal. 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 tube and pipe and beam 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.
ABOUT THE AUTHOR:
David Leonhardt runs a freelance ghost writer service. He wrote this article for a metal tube, angle and beam bending & rolling client. See their steel forming processes to bend metal tubing and pipes.
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