Once a pipe or tube has been fabricated, post-fabrication treatments are required for the tube to be formed into a usable product.
Tube bending is one of the most commonly used post-fabrication processes and can be performed manually or by the use of tube bending machinery, using either cold or hot forming methods.
Tube bending machinery is used to create tubes for use in the aerospace, agricultural, medical, electrical, automotive, and construction industries.
There are various types of tube bending machines.
Automated, computer-controlled tube bending machinery is used in the process of shaping pipes and tubes. However, tooling is also used.
Where tooling is used in the tube bending process, the setup of the chosen tool is crucial as tooling costs can be expensive, and errors are costly.
Ram bending is a traditional and cost-effective tube bending method that’s still used today.
The process entails securing the tube or pipe at two external points. A bending ram presses down onto the workpiece’s central axis. Power then shifts vertically through a ramming cylinder. The ram pushes the pipe or tube up against a pair of fixed rollers, bending the tube around the die.
Ram bending is typically used in the manufacture of automobile exhaust pipes and for forming electrical conduits.
Rotary draw bending
Rotary draw bending is used where precise pipe diameters and a high-quality finish are required.
The process entails using a die set that consists of a stationary counter-die and a forming die with a fixed radius. The pipe is pulled through the counter-die, which pushes the piece laterally onto the forming die along the axis of the bend.
Rotary draw bending is highly accurate. Also, some draw bending machines can be programmed to repeat very complex operations on multiple tubes, improving precision and uniformity in a production run.
Rotary draw bending machinery is commonly used for several applications, including:
- Conduit bending
- Automobile chassis and roll cages
- Decorative iron work
- Trailer frames
Ring roll bending
Ring roll bending is used to form pipes and tubes with centre line radiuses and large circumferences. The method uses benders that are usually made up of three triangulated ring rolls organized on individual shafts.
As the tube passes through the rollers, the upper roller presses down, forcing the piece against the lower rollers and making the tube bend. Ring rollers are usually hydraulically or manually adjustable.
Ring roll bending generally creates uniform cross-sections with minimal deformation. The process is usually used for making drum rolls, truss pipes, appliance frames, and other rounded, large-diameter components.
Mandrel bending is a reasonably precise process that produces few deformations in pipes or tubes. For that reason, mandrel bending is used to bend thin materials to a closer radius than they would usually sustain without deforming or breaking.
A mandrel is a flexible piece that is inserted into the inside of the tube at the point where the tube needs to be bent. The mandrel protects the tube’s interior from unwanted deformation while the piece is drawn through a counter-bending die and forming die set.
This method of tube bending is typically used to fabricate heat exchange and intake tubing, and exhaust pipes.
Tube bending machinery is a post-fabrication process that is used to form tubes into a useable product, superseding the need for manual intervention and often working in conjunction with computer automation software.