Thermal Expansion Steel Tube Quality Defects

Flattening and reducing deformation in the thermal expansion steel pipe: The billet tube head contacts the tapered roller in the cantilever state and moves forward under the action of friction. At this time, the blank tube is only in contact with the roll and not on the plug. The deformation is mainly flattened and reduced in diameter. When the diameter reduction is too big, the pipe wall sometimes thickens. The size of the flattening reducing zone is related to the position of the plug. The adjustment of the position of the plug is mainly to smoothly realize the primary site of the blank tube and create good mechanical and kinematic conditions for the secondary site and the wall-reducing and expanding deformation.

Deformation of reducing wall and expanding diameter in the thermal expansion steel pipe: It is the primary deformation zone of cross rolling and expanding pipe. In this area, the billet tube is decreased in-wall and enlarged in diameter. Since the elongation coefficient is close to 1, according to the law of constant metal volume, almost all the metal whose tube wall is thinned becomes the metal that needs to be supplemented due to the increase in the outer diameter. The deformation of the metal mainly occurs in the circumferential and radial directions of the blank tube. Since both the roll and the plug can move along their respective axis directions, as long as the positions of the roll and the plug are changed, the specifications of the expanded waste pipe can be modified. After the position of the roll and the plug are adjusted. The deformation of the reduced wall area will not change.

Rounding deformation: After the blank tube is deformed by decreasing the wall and expanding its diameter, it no longer contacts the plug and enters the rounding area. Under the action of surface friction, the waste pipe smoothly leaves the deformation zone.