Technology of straight seam high frequency resistance welded steel pipe

Frequency welded pipe production process, how to ensure the quality of products meet the technical standards and the needs of customers, we have to factor in steel production process affect product quality analysis. Through the company Φ76mm high frequency welded steel pipe(erw steel pipe) unit for a month unqualified statistics that affect steel product quality in the production process elements include raw materials, welding process, the roll adjustment, roll material, equipment failure, the production environment and other reasons seven aspects. Wherein the raw materials accounted for 32.44%, accounting for 24.85 percent the welding process, the roll adjustment accounted for 22.72%, accounting for 80.01% the sum of the three, is the main link. The four elements of roll materials, equipment failures, and other production environment and other reasons, the impact on the quality of steel products accounted for 19.99%, it is a relatively minor part. Thus, in the steel production process, to deal with raw materials, welding technology and roll adjustment control to focus on three aspects.

Strip yield point and high tensile strength, it will cause difficulties in forming the strip, particularly when thick wall, resilient materials, large, large deformation stress in the presence of pipe welding, weld cracks easily. When the tensile strength of steel exceeds 635 MPa, elongation of less than 10% of the strip during welding seam prone to crack. When the tensile strength is less than 30 0MPa, the strip material in the molding process due to the soft, easily wrinkled surface. Visible, the mechanical properties greatly influence the quality of the steel pipe, steel pipe strength of the material should effectively control the quality. ) The strip surface defects on steel strip surface quality defects are common Camber, wavy edge slitting eating several, camber and wavy generally appear in the cold-rolled strip rolling process, by reduction caused by improper control. In the steel molding process, camber and wavy cause deviation or flip the strip, easy to produce steel pipe weld lap welding, affecting the quality of steel pipe. Eating strip edge (ie, the strip edges jagged uneven phenomenon), generally appear in the tape slitting, slitting machine causes the disc blade blunt or sharp result. Because eating strip edge, always partial lack of meat, steel strip in the welding easy to crack, crack and affect the stability of the weld quality.

Effect of Geometry on the quality of steel strip when the strip width is less than the tolerance, the pressing force is reduced when the welded steel pipe, steel pipe weld welding so weak, cracks or open tube; when the width of the strip greater than tolerance, the pressing force is increased when the welded steel pipe, steel pipe welds appear beak, lap welding and other welding defects or burrs. Therefore, fluctuations in the strip width, not only affects the accuracy of the outer diameter of the steel pipe, but also seriously affect the quality of the surface of the steel pipe. Requirements section of the same thickness difference does not exceed the predetermined value of the steel pipe, which requires a high degree of uniform wall thickness of the pipe, fluctuations in the thickness of the strip, the same volume will be transferred to the allowable value of the wall thickness of the finished steel strip thickness difference exceeds the difference so that a large number of steel tube wall thickness exceeds the allowable deviation and scrap judgment. fluctuations affect not only the thickness of the finished steel thickness accuracy, and because the strip of varying thickness, the steel pipe during welding, extrusion pressure and welding temperature instability, resulting in a unstable weld quality when welding steel. Further, since the interior of a steel material defects exist sandwich, impurities, such as trachoma, it is also an important factor affecting the quality of steel. Therefore, before steel welding, to check each roll strip surface quality and geometry of the strip does not meet quality standards, not production, so as to avoid unnecessary losses.