Cold-formed steel, cold-formed rectangular tube through the one-way roller contacts the outer tube forming the outer wall so that the strip bending moment, bending line will produce cold-formed compression, the compression effect makes bend lines longitudinally elongated, bent accumulation of the metal appears thicker, which is cold-formed compression / thickening effect.

1) The advantage of cold-formed is small rebound, forming accurate, and as long as the roller type accurately, inside corner molding R more accurate. The advantage is that it can be cold-formed side bent when you can not be cold-formed, for example, square and rectangular tube top / side synchronous bending and finishing. You can also cold-formed bent R <0.2t inside corners and walls without fracture.

2) There is a disadvantage of cold-formed stretching / thinning effects. It will produce cold-formed bends stretch, stretching effect of the longitudinal length of the bend lines shortened; second, cold bending of the metal due to stretching and thinning. The disadvantage is cold-formed in the top / side of sync when cold-formed, since the upper and lower rollers while generating pressure, easy molding force beyond the critical point, causing instability concave edge, and can also affect the stable operation of units and forming quality.