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The 2022 Ultimate Guide to Pipe Bend Process and Machines

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What is the pipe bender process?

Tube bending and pipe bending is the metalworking process of bending tubes and pipes into various shapes for different purposes. Tubes formed out of the tube bending process are not limited to any particular metal, the process works on different materials including most metals and alloys.

Therefore, tube bending and pipe bending is used so the tube can be reshaped as a whole, without cutting the tube itself. Using processes like cutting and welding the tube can weaken the integ

Pipe bending and tube bending can be achieved in various ways. Factors to be considered include the size of the pipe or tube to be bent, the wall thickness, the desired radius, and, of course, the material.

Pipe bending machine

rotary draw bender

While the end result of pipe bending is a simple one–a tube or pipe bent into the right shape–many people find that finding the right process and the right material can be a matter of skill. As such, for every type of pipe bending machine, there will be a specific sort of application that may be included or excluded.

The most common method of pipe and tube bending is done on what is called a rotary draw pipe bending machine or profile bending machine(Some countries also call it an angle roll or angle roller).

Tube and pipe bending machines fall into several categories, these bends can be simple angles, circular arcs, or complex shapes like exhaust pipes. Many benders can also fit square shapes, but the standard tube and pipe bender usually accommodate circular shapes.

Rotary draw bending

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. Rotary draw bending of pipe bending technology is much more precise because the die sets have a consistent CLR and centerline radius.

The rotary draw bending process

Round pipe, as well as round, square and rectangular tubing, is clamped into a form and drawn over a die with the desired radius. Each die must conform not only to the desired radius, but also to the outside dimensions of the material to be bent. Once set up, however, the method can produce quality parts relatively quickly.

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.

Available with an indexing plate, the rotary draw automatic pipe bending machine is very popular for applications like frames, automotive parts, handles, handrails manufacturing, and so on. With a CNC system, they can provide complex and sophisticated tooling to perform critical bends and high performance.

Advantages

  • Precise and Repeatable
  • Fast

Disadvantages

  • Machinery is dedicated to the bending process and thus is less flexible
  • Cost for initial machine
  • Requires Tooling for each different tube/pipe diameter used and for each radius formed

Roll bending

The steel pipes will be forced through a series of rolls that apply pressure to the materials and gradually bend and form the profiles. This bending method is very ideal for processing long strips of pipes and long gentle bends.

Roll bending process

With the roll bending process, pipe or tubing is passed through 3 or more rollers which induce the curve at the point of contact. The parts are rolled back and forth until the desired radius is achieved. Multiple dies are required to hold the outside diameter of the sections, but the three rolls of the profile bending machine can be manipulated to create a very wide range of radii.

Roll bending machine

The roll bending machines only produce very little deformation in the cross-section of the stock material.

Stepping up in capacity, three-roll benders (also called “section bending machine,” and “angle roll”) can bend pipe and tubing up to 24” OD pipe and 20×20 tube. Rolling sizes this large is not that common; a more common range would be from 2in to 8in outside diameters.

Three-roll angle rollers are used to create parts for equipment as well as sections curved for construction.

Advantage

A variety of tube radii can be performed on the same machine including variable angles.
Sections such as pipe, bars, and angle can also be formed with this method

Disadvantage

The slower process as each tube is manually processed with difficulty in obtaining exacting results.
Thin-walled tubing can easily collapse if the bend radii are too small.
Accuracy is poor
Repeatability is Poor

Induction Bending

Induction bending is used for a large variety of applications for larger radius pieces, thin-walled pipes, short-radius bends, and so on. The induction bending machine requires no mandrel. The induction coil will be placed around a small section of stock materials at the bend point. They can provide high-precision bends with desired angles. Accurate spools can be simply manufactured by this type of automatic pipe bending machine.

Induction Bending Process

An electric coil heats a small section of the pipe or tube while machinery pushes it to a swing arm that induces the curve. Water cools the section once it has been bent to the correct radius. Pipe up to 66in in diameter can be bent. The process can also provide close tolerance for tight bends.

Applications include processing pipes, component parts of equipment, and curved structural members.

5 things for creating high-quality pipe bend without causing damage to the materials

Weld Seam

Most projects make use of welded seam tubes, as they are economical and just as strong as seamless tubes. As a beginner, you should keep in mind to turn this weld seam towards the inside of the bend, to maintain a good appearance of the tube.

Tube Elongation

Tube elongation is the maximum length to which the tube can be stretched before it breaks down. The greater the bend, the greater the elongation. Therefore, make sure that the tube you are bending can withstand the bend angle you require.

Multiple Bends

When making multiple bends in a tube, remember to keep sufficient distance between two consecutive bends for the purpose of clamping the tube. Also, keep in mind that multiple bends can increase the cost and time for the project itself.

Standard Tubes vs Custom Tubes

Certain projects may call for custom tube shapes and sizes. However, whenever possible and applicable prefer using standard tube shapes and sizes. They provide the benefit of saving costs due to the greater availability of tooling at the right price.

Avoiding High Bend Angles

If it is possible, avoid taking the bend angle over 90 degrees. Higher bend angles can lead to a greater probability of tube collapse or material deformation.

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