The roll bending process can make metal cylinders or circles, and while these cylinders or circles are made with a sets roller, that process is not called roll forming.
Although the roll bending deformation is limited to a local area of the material, the rebound effect affects the accuracy of the roll bending part. There are many factors that affect the spring back, and these factors are difficult to control. The accuracy of the bending part caused by the spring back has always been the key to roll bending production.
Roll forming complex metal shapes with multiple bends and/or punch patterns. In the roll forming process, a coil or long individual strips are fed through a roll forming line through a progressive series of mated dies, which turns a coiled strip of sheet metal into the desired shape( converts the flat sheet to a contoured cross-sectional profile).
The more advanced the desired shape, the more rollers the material goes through. The roll forming line can bend metal, form metal into tubes, create metal maze-like structures, and punch the metal with holes during the process.
The differences between roll forming and roll bending
Roll forming and roll bending are two types of metal fabrication processes that involve gently reshaping metal into functional shapes. However, there are significant differences between roll forming and roll bending:
Roll bending is a kind of metal forming, whereas roll forming is a kind of metal fabrication.
The main difference is that while rolling forces the metal to flow into a different shape, sheet/profile metal forming works by causing deformation in the material overall, with minimal effect on the grain structure or the thickness of the material.
Pros of roll bending and roll forming
- No heating required
- The better surface finish obtained
- Superior dimension control
- Better reproducibility and interchangeability of parts
- Improved strength properties
- Directional properties can be minimized
Cons of roll bending and roll forming
- Higher forces required for deformation
- Heavier and more powerful equipment required
- Less ductility available
- Metal surfaces must be clean and scale-free
- Strain hardening occurs (may require intermediate anneals)
- Imparted directional properties may be detrimental
- May produce undesirable residual stresses
Works Cited: Cold Bending And Hot Bending In Pipe Bending