What is the difference between tube bending and tube rolling?
The main difference lies in the bending radius and the machines used.
- With tube and pipe bending, the bending radius is tighter and can be 1.5 to 5 times the pipe dimension. Example: For a pipe with a diameter of 50 mm, the average bending radius can be between approximately 75 mm and 250 mm.
- With tube roll bending (tube rolling), the average radius is much larger and ranges from five times the pipe dimension to ‘infinity’. Example: For a pipe with a diameter of 50 mm, the minimum rolling radius is between 250 mm and infinity.
Another difference concerns the machines:
- A mandrel bending machine is used for tube bending.
- For tube rolling, on the other hand, a CNC rolling machine is used, which can bend round, square or rectangular tubes as well as various profiles.
What is the bending radius of a pipe?
The bending radius refers to the size of the circular arc by which a pipe is bent.
When bending pipes and tube rolling, the radius is created in two different ways:
- When bending pipes or tubes, the radius is created by a bending die that is specially manufactured for each cross-section and each radius. Example: A specific die is used for a round tube with a diameter of 50 mm and a mean radius of 100 mm. A different die is required for Ø 50 with a radius of 125 mm. For square or rectangular hollow sections, the same die can sometimes be used for several cross-sections.
- In tube rolling, the radius is created by passing the tube through a roller system with three rollers one or more times. In contrast to bending, the same rollers can be used to create different radii on the same tube for Ø 50. Roll bending thus enables complex geometries that cannot be achieved with a CNC tube bending machine.
What metal alloys are used to manufacture curved tubes?
Tecnocurve specialises in bending and rolling tubes, hollow sections and profiles made from the following alloys:
Which types of tubes can be bent?
Tecnocurve can bend the following types of tubes and profiles:
- Round tubes
- Square hollow profiles
- Rectangular hollow profiles
- Special profiles (open or closed)
What is the difference between a tube and a section?
- A tube has a round cross-section.
- A section, on the other hand, has a square or rectangular cross-sectional shape.
A section is either open (e.g. ‘C’ or ‘U’) or closed.
Find out more in our blog article.
What happens to the metal pipe when it is bent?
In the bending zone, it undergoes cross-sectional deformation.
- The pipe cross-section tends to become ovalised.
- The outer wall becomes thinner.
- The inner wall, on the other hand, becomes thicker.
- In addition, the tube lengthens.
Special tools can reduce this deformation, but never eliminate it completely.
What is springback?
During bending, the metal tube is shaped using clamping devices and dies.
As soon as the tube is removed from the tool, it tends to partially return to its original shape.
Example: When the bending machine bends at an angle of 45°, the resulting angle is often only 42–43°.
This deviation is called springback and depends on the ratio between the cross-section, radius and bending angle.
What does cold forming of metals mean?
Cold forming is a mechanical process in which metal – in this case, a pipe or special profile – is shaped using machines and special tools.
The tools generate forces that bring the pipe into the desired shape according to the technical drawing.
Tecnocurve performs two types of cold forming:
- Pipe bending
- Tube rolling (roll bending)
What is the difference between cold and hot bending?
The difference lies in the temperature during tube manipulation:
- Cold bending: Bending at room temperature
- Hot bending: The tube is heated
Hot bending allows for particularly tight radii (less than 1.5 times the diameter), but is significantly more expensive and impairs the elastic properties and material behaviour of the tube.
What types of tube manipulation does Tecnocurve carry out?
Tecnocurve specialises in tube bending and rolling.
We also carry out other processes, but always as a secondary process to bending or tube rolling:
