What are the forming methods of square tube?

1, solid bending

Solid bending, as the name implies, is compacted bending, and the inner and outer rollers and the inner and outer walls of the tube billet are compacted bidirectional.

1) The advantages of solid bending are small rebound, accurate molding, and as long as the roller shape is accurate, the R of the inner Angle molding is more accurate.

2) The disadvantage of solid bending is the stretching/thinning effect. First, the solid bending will cause the bending point to produce tension, tensile effect to shorten the longitudinal length of the bending line; Second, the metal at the real bend will become thinner by stretching.

2. Empty bend

Empty bending is the bending moment formed by the one-way contact between the outer roll and the outer wall of the tube blank to bend the strip material. Empty bending will cause the bending line to compress, and the compression effect will make the bending line lengthwise, and the metal at the bending place will accumulate and become thicker, which is the compression/thickening effect of empty bending.

1) The advantage of empty bending is that the side length can be bent when solid bending is not possible, such as synchronous bending and finishing of the top/side of the square rectangular pipe. Air bend can also bend R< The inner Angle of 0.2t without fracture of the tube wall.

2) The disadvantage of air bending is that in the upper/side synchronous air bending, because the upper roll and the lower roll produce pressure at the same time, the forming force is easy to exceed the critical point, resulting in the side instability and concave, and will also affect the stable operation of the unit and the forming quality. This is also the square and round tube air bending forming characteristics of different.