In Fabricating, tube bending plays one of the most important parts. There are so many products manufactured using tubing it would be somewhat impossible to list them all. Whether your bending tubes for a roll cage in a race car, making trumpets, trombones or other musical instrument, stair railings in high rise building or precision hydraulic lines in an aircraft, the precision forming of tubes is a critical part of manufacturing today.
How that tubing is formed depends on a variety of factors like material type, wall thickness, quantity required and accuracy desired. Tube benders are usually purchased based on these factors and while there may be a variety of methods to produce the desired accuracy, there is usually only one that can address all the factors involved. But what are these methods of tube bending? How do they work and what are the benefits of one tube bending process over another? Below we will break down the basics on these different methods of tube bending and provide you the advantages and disadvantages of each.
Press Bending is a simplistic form of tube bending. Using a press brake, ironworker, hydraulic press or similar machine a simple “bend die” is pressed against the tube or pipe which is straddled across two fixed supports forcing it to conform to the shape.
Roll Bending is another method of tube bending that utilizes a 3 or 4 roll machine called an Angle Roll or Section Roller to pull the tube or pipe through the rolls while pressing the tubing into an increasing bend. This method, much like Press Bending, utilizes a triangular pattern of support rollers and pressing roller, however unlike Press Bending this method can bend a variety of angles utilizing the same type of rollers as the tube or pipe moves through the bending sequence by the powered and turning rollers. This method can be an easy and precise way to bend a variety of radii without the need for specific tooling for the desired bend radius desired.
Rotary Draw Bending is by far the most popular form of tube bending as it is easiest to control, more precise,repeatable and a relatively affordable tube bending system. A Rotary Draw Bending system is made up of three different tools, the Clamping Die, the Pressure Die and the Radius Die that hold and form the tube throughout the bending process. The tube is clamped to the bend die and is ‘drawn’ around the die by the machine by either hydraulic or electric methods. As the bending die rotates the tubing is held in place firmly against the rotating bend die by the pressure die.
Mandrel Tube Bending is really not a separate process from the above, Rotary Draw Bending at all, but rather an addition to