In the process of producing high frequency welded pipes, welded pipe manufacturers will encounter scratches on the surface of pipes, which are mainly caused by guide rollers and extrusion rollers.


1. Scratches produced by guide rollers usually occur on both sides of high frequency welded pipes. Scratches are characterized by great continuity. Reasons include:
(1) The height of guide sleeve is incorrect, for example, the guide roller bearing is damaged, and the guide roller can not control the high frequency welded pipe well, which causes scratches between the guide sleeve and the friction force.
(2) When the guide roll deviates from the rolling center line of the high frequency pipe production line, the relative difference between the guide sleeve and the guide roll axis is too large, resulting in scratches on both sides of the high frequency welded pipe.


2. Scratches caused by high frequency welding extrusion roll mainly occur at the bottom of high frequency welding pipe. Reasons include:
(1) The mismatch of holes results in scratches on the surface of high frequency welded pipes, and the non-conforming factors of holes are as follows: the bearing of extrusion roll is damaged, the extrusion roll moves axially, the dimension of extrusion roll hole is different, the height position of two extrusion rolls is different, and the bending and assembly of extrusion roll is unstable.
(2) The extrusion roll height does not match. The lower edge of the extrusion roll hole shall be the same as the height of the rolling line, and the height of the guide roll shall be determined by the wall thickness of the high frequency welded pipe. If the guide roll is too low, the edge of the extrusion roll hole will scrape the bottom of the HF welded pipe.
(3) Inadequate extrusion on the extrusion roll. Especially in the twin-roll extrusion roll device, when the extrusion pressure is insufficient, the tension of high-frequency welded pipe will appear on the elevation angle, making the hole edge R rounded, resulting in scratches under the high-frequency welded pipe. When the extrusion roll hole R is round and sharp, scratches will increase.