What Are The Square Tube Forming Methods?
The way in which the tube is formed is called bending, and the way in which the square tube is formed is called bending. There are two basic methods of bending forming: solid bending and empty bending.
The solid bend, as the name implies, is the compaction of the bend, and the inner and outer rolls and the inner and outer walls of the tube blank are biaxially compacted during the solid bending.
The advantage of the solid bend is that the rebound is small, the molding is accurate, and as long as the roll shape is accurate, the R formed at the inner corner is relatively accurate.
The disadvantage of solid bending is the stretching/thinning effect. First, the solid bend causes the bend to be stretched, and the stretch effect shortens the longitudinal length of the bend line. Second, the metal at the bend bend becomes thinner due to stretching.
The hollow bend is formed by the unidirectional contact between the outer roller and the outer wall of the tube blank to form a bending moment to bend the strip. The air bend causes the bending line to compress, and the compression effect causes the bending line to extend longitudinally, and the metal at the bend is thickened. This is the compression/thickening effect of the empty bend.
The advantage of the hollow bend is that it can bend the side length when the solid bend cannot be performed, such as the upper side/side edge of the square tube and the simultaneous bending and finishing. The hollow bend can also bend the internal angle of R < 0.2t without causing the tube wall to break.
The disadvantage of the hollow bend is that when the square tube is synchronized with the upper side/side side, the forming force tends to exceed the critical point due to the simultaneous pressure of the upper and lower rolls, causing the edge to be unstable and concave, and also affecting the stability of the unit. Operation and molding quality. This is also a different feature of the rectangular tube and the tube when it is formed by air bending.
In practical applications, these two basic methods should be configured in a reasonable process position according to the product requirements in the square tube forming. Attention should be paid to the effect of the stretch/thinning effect of the solid bending forming and the compression/thickening effect of the air-bending forming on the product quality, otherwise the side tube will be concave when the square tube is formed, the longitudinal direction of the finished tube is warped, and it is difficult to correct straight.