If the used high frequency tube mills refers to the chemical composition and mechanical properties of welded tube blanks that require certain inspection methods to be known as invisible defects; then, those defects that can be seen only by vision are called tube blanks. Overt defect.

The dominant defects of the welded tube blank of the used high frequency tube mills generally include cracked edges, broken edges, sawtooth, pitting, scratches, roll marks, dark spots, edge burrs, sickle bends, wrinkles, waves, edge warping, and points. Layers, warped skins, pinholes, sticky rolls, soft spots, rust, oxide layers, towers, loose rolls, etc. Let me introduce you to the causes of cracked edges and the effect of cracked edge billets on welded pipes.

Sickle bend

The sickle elbow refers to the phenomenon of lateral bending of the tube blank. The standard stipulates that the sickle bend of the hot-rolled tube shall be no more than 3mm/m, and that of the cold-rolled tube shall be no more than 2mm/m. The possibility of hot-rolled narrow tube blanks without trimming is the greatest.

The reason for the sickle bend:

(1) The reduction of both ends of the roll fluctuates during the production of tube blanks.

(2) The temperature difference between the two sides of the strip is large when the strip is rolled.

(3) The receiving device of the slitting machine is inconsistent with the center of the tension station and the shearing machine.

The influence of sickle bend on welded pipe production:

(1) During the molding process, the long side will be "surplus", which is easy to produce a molding bulge.

(2) "Lap welding" or dislocation of the weld seam is easy to occur during the welding process, and the weld seam strength cannot be guaranteed.

(3) Welding seam swings left and right, it is not easy to control the depth of external burr removal.

(4) The forming forces on both sides of the sickle elbow tube blank are different. During the forming and deformation process, the tube blank has a tendency to bend forward, and the formed tube blank is prone to "off-track", causing production to stop.

About the used high frequency tube mills welded tube defects (6) the introduction of the sickle bend, and the influence of the sickle bend on the quality of the welded pipe, I hope it can help you.