How to Control the Size of Welded Spiral Steel Pipes
The spiral steel pipe feeds the steel strip into the welded pipe unit and is rolled by multiple rollers. The strip steel is gradually rolled up to form a circular billet with an open gap. The amount of pressurization of the squeeze roller is adjusted so that the weld gap is controlled at 1~ 3mm, and make the weld ends flush.
If the gap is too large, the proximity effect is reduced, the eddy current heat is insufficient, and the weld intergranular joint is poor and unfused or cracked.
If the clearance is too small, the proximity effect will increase, the welding heat will be too large and the welding seam will be burned; or the weld will form a deep pit after being squeezed and rolled to affect the surface quality of the weld.
After the two edges of the tube are heated to the welding temperature, under the extrusion of the squeezing roll, common metal crystal grains are formed to infiltrate and crystallize with each other, finally forming a firm weld. If the squeezing force of the spiral steel pipe is too small, the number of common crystals formed is small, the strength of the weld metal is decreased, cracking will occur after stress, and if the squeezing force is too large, the molten metal will be extruded out of the weld seam. Not only reduces the weld strength, but also produces a large number of internal and external burrs, and even lead to welding gaps and other defects.